O
Obel grades
Obesity
Oligofructose
Omega 3
OST/OGT - Oral Sugar Test/Oral Glucose Test
Osteomyelitis/Septic Pedal Osteitis
Overweight - see Obesity
Oxidative Stress
Obesity
Oligofructose
Omega 3
OST/OGT - Oral Sugar Test/Oral Glucose Test
Osteomyelitis/Septic Pedal Osteitis
Overweight - see Obesity
Oxidative Stress
Obel grades
Meier A, McGree J, Klee R, Preuß J, Reiche D, de Laat M, Sillence M.
The application of a new laminitis scoring method to model the rate and pattern of improvement from equine endocrinopathic laminitis in a clinical setting.
BMC Vet Res. 2021 Jan 7;17(1):16. doi: 10.1186/s12917-020-02715-7. PMID: 33413384; PMCID: PMC7791853.
Keywords: Diagnosis; Equine metabolic syndrome; Insulin; Laminitis; Obel.
Meier A, de Laat M, Pollitt C, Walsh D, McGree J, Reiche DB, von Salis-Soglio M, Wells-Smith L, Mengeler U, Mesa Salas D, Droegemueller S, Sillence MN
A “modified Obel” method for the severity scoring of (endocrinopathic) equine laminitis
PeerJ published 07 June 2019. doi.org/10.7717/peerj.7084
Menzies-Gow NJ, Stevens KB, Sepulveda MF, Jarvis N, Marr CM
Repeatability and reproducibility of the Obel grading system for equine laminitis
Vet Rec. 2010 Jul 10;167(2):52-5. doi: 10.1136/vr.c3668
The original grading scale for assessing laminitis severity was developed by Niles Obel and described in his PhD thesis Studies of the Histopathology of Acute Laminitis, published in 1948.
Grade 1: When standing the horse incessantly shifts its weight from leg to leg (paddling). No lameness is evident at the walk, but a short stilted gait is noted at the trot.
Grade 2: The horse moves quite willingly but with a stilted gait at the walk. A foot can be lifted off the ground without difficulty.
Grade 3: The horse is reluctant to move at all. It is difficult to lift a foot off the ground.
Grade 4: The horse will not move without being forced, and may lie down more than usual. It is almost impossible to lift a foot off the ground.
Obesity (Adiposity, Fat, Fatness)
Obesity in horses involves one or more of generalised or localised excessive adipose tissue and a predisposition to weight gain or resistance to weight loss, and is often defined by a body condition score (BCS) ≥7/9 and/or a total body fat percentage of ≥20%.
Obesity is one of the 3 factors that make up Equine Metabolic Syndrome, the others being insulin resistance and a predisposition to laminitis. This can be overall obesity and/or regional adiposity (fat pads).
Being overweight can lead to heart, lung and joint/mobility problems as well as increasing the risk of EMS and laminitis (and possibly PPID - many ponies that are obese when young develop EMS and then PPID). The longer a horse remains obese, the greater the associated health risks.
Why do some horses become obese when others kept the same way do not?
Possible reasons include:
- genetic predisposition, a more efficient energy metabolism;
- increased appetite, leptin resistance;
- possibly differences in nutrient digestion or absorption.
Some breeds, especially ponies, seem to be more prone to becoming obese than others - these are often native ponies from areas with harsh winters.
Risk factors for obesity:
- overfeeding - feeding more hard feed than the horse needs (over-estimating workload), too much (high nutrient) grass;
- lack of exercise;
- elimination of seasonal weight loss by maintaining weight in winter rather than allowing horse to live off autumn fat stores;
- not recognising when a horse is overweight.
Methods of measuring obesity/adiposity
Current methods of measuring obesity/adiposity tend to be subjective (e.g. Body Condition Scoring), tend to measure subcutaneous fat rather than total body fat, and may not be accurate for comparing different breeds.
Assessment of body condition and bodyweight - Rebecca Carter, Alexandra Dugdale - p 393 Equine Applied and Clinical Nutrition (2013)
Dugdale AH, Grove-White D, Curtis GC, Harris PA, Argo CM. (PubMed)
Body condition scoring as a predictor of body fat in horses and ponies.
Vet J. 2012 May 10. [Epub ahead of print]
"the power of log-transformed BCS as a predictor of eTBF% decreased as BCS increased.".."The data suggest that BCS descriptors may warrant further consideration/refinement to establish more clinically-useful, sub-classifications for overweight/obese animals."
Dugdale AH, Curtis GC, Cripps PJ, Harris PA, Argo CM. (PubMed)
Effects of season and body condition on appetite, body mass and body composition in ad libitum fed pony mares.
Vet J. 2011 Dec;190(3):329-37. Epub 2010 Dec 10.
"Body fat content was exponentially associated with increasing BCS but BCSs >6 were not useful indicators of actual body fat."
New methods include
- deuterium dilution technique (D2O)
Assessment of body fat in the pony: part II. Validation of the deuterium oxide dilution technique for the measurement of body fat.
Equine Vet J. 2011 Sep;43(5):562-70.
"This study provides the first validation of the D(2) O dilution method for the minimally-invasive, accurate, repeatable and objective measurement of body water and fat in living equids."
- bioelectrical impedence
Comparison of bioelectrical impedence with other methods for assessing adiposity in horses and ponies changing from moderate to obese body condition
S.J Potter, N.J Bamford, P.A. Harris and S.R. Bailey
Bioelectrical Impedance Analysis (BIA) was shown to correlate moderately well with deuterium dilution determination of total body fat (considered the gold standard). Body Condition Score (Henneke) showed a slightly weaker correlation and there was no significant correlation with cresty neck score. However, a lot more research is necessary before BIA can be used in practice.
Managing Obesity in Pasture-Based Horses
Iveta Becvarova and R. Scott Pleasant - Vetlearn.com April 2012 (login required)
Obese horses - Christy West The Horse March 2007
Redwings video below showing how to body condition score your horse, using the modified 0-5 point scoring system, by Dr Teresa Hollands - as shown in the October 2013 The Laminitis Revolution 2 webinar. Horses that are too thin, too fat and just right are used to demonstrate how to assess BCS, including a typical underweight PPID horse and a typical overweight EMS/PPID pony.
The body should be divided into 3 sections: neck, middle and bottom, and each section scored separately by feeling for fat over the skeleton. 3 is the perfect score. Body condition scoring should be carried out ideally every 2 weeks on all horses, and the results recorded.
Neck - there shouldn't be any fat or crest above the nuchal ligament - there is no muscle above the nuchal ligament, anything felt here is fat, not top line. A large crest will score 4 or more, bulges and corregation in the crest will probably score 5.
The shoulder blade should be well defined - if you run your hand down the side of the neck, it should come to a stop at the shoulder blade.
Middle - you should be able to feel the ribs, like feeling stair banisters through a velvet curtain, but hardly see them. If you can neither see nor feel the ribs, that scores 4 or more.
If you place your hand over the backbone, it should form a nice curve - a triangle is too thin, flat is too fat.
Bottom - you should be able to feel just feel the top of the pelvis, the hip bone and the tail bone. If you can't see or feel these bones, that scores 4 or more.
In summary, if you can feel AND see bones, the horse is too thin.
If you can neither feel nor see bones, the horse is too fat.
The body should be divided into 3 sections: neck, middle and bottom, and each section scored separately by feeling for fat over the skeleton. 3 is the perfect score. Body condition scoring should be carried out ideally every 2 weeks on all horses, and the results recorded.
Neck - there shouldn't be any fat or crest above the nuchal ligament - there is no muscle above the nuchal ligament, anything felt here is fat, not top line. A large crest will score 4 or more, bulges and corregation in the crest will probably score 5.
The shoulder blade should be well defined - if you run your hand down the side of the neck, it should come to a stop at the shoulder blade.
Middle - you should be able to feel the ribs, like feeling stair banisters through a velvet curtain, but hardly see them. If you can neither see nor feel the ribs, that scores 4 or more.
If you place your hand over the backbone, it should form a nice curve - a triangle is too thin, flat is too fat.
Bottom - you should be able to feel just feel the top of the pelvis, the hip bone and the tail bone. If you can't see or feel these bones, that scores 4 or more.
In summary, if you can feel AND see bones, the horse is too thin.
If you can neither feel nor see bones, the horse is too fat.
For a demonstration of body condition scoring (using the 5 point system) see The Blue Cross Fat Horse Slim video below:
WHW - Right weight advice - videos and leaflets on recognising obesity and managing a horse's weight
Body Condition Scores - The Henneke System - www.gerlltd.org
Equine Body Condition Score - www.thehorse.com
Research and articles:
Furtado T, Perkins E, Pinchbeck G, McGowan C, Watkins F, Christley R
Exploring horse owners’ understanding of obese body condition and weight management in UK leisure horses
Equine Vet Journal published online 01 October 2020. doi.org/10.1111/evj.13360
Knowles EJ, Grieve L
Clinical insights: Equine obesity
EVJ Sept 2020 52,5 635-638. Published online 04 August 2020. https://doi.org/10.1111/evj.13307
Furtado, Tamzin
Exploring the recognition and management of obesity in horses through qualitative research
PhD thesis Liverpool University May 2019
Equine obesity: the most common risk factor for laminitis in the UK? David Rendle, Pat Harris, Nicola Menzies-Gow, Veterinary Times Nov 2019 (file)
Rendle D, McGregor Argo C, Bowen M, Carslake H, German A, Harris P, Knowles E, Menzies-Gow N, Morgan R
Equine obesity: current perspectives
UK-Vet Equine Sept/Oct 2018 Vol 2 No 5
Morrison, Philippa K
Equine Obesity: Concepts and Mechanisms
PhD thesis University of Liverpool Sept 2015
Robin CA, Ireland JL, Wylie CE, Collins SN, Verheyen KLP, Newton JR
Prevalence of and risk factors for equine obesity in Great Britain based on owner-reported body condition scores
EVJ March 2015 47, 2 196-201. First published online 16 April 2014 and in full online 04 August 2020. https://doi.org/10.1111/evj.12275
Vet J. 2012 Nov;194(2):179-88. Epub 2012 Oct 30.
Weight loss resistance: a further consideration for the nutritional management of obese Equidae.
Argo CM, Curtis GC, Grove-White D, Dugdale AH, Barfoot CF, Harris PA.
7th International Equitation Science Conference 27th-29th October 2011 Conference Proceedings Session 05 Poster 25
Variation in body condition in small groups of horses
Giles S, Harris PA, Nicol CI, Rands SA
More than 27% of 127 horses and ponies in Somerset were found to be obese (assessed using BCS and CNS) in February.
The difference in body condition score between members of the same herd was questioned.
Dugdale, Alex (2011), Doctoral thesis, University of Liverpool.
Aspects of adiposity in ponies
Dugdale AH, Curtis GC, Harris PA, Argo CM.
Assessment of body fat in the pony: part I. Relationships between the anatomical distribution of adipose tissue, body composition and body condition.
Equine Vet J. 2011 Sep;43(5):552-61.
Vet Immunol Immunopathol. 2009 Feb 15;127(3-4):286-94. Epub 2008 Oct 31. (PubMed)
Effect of body condition, body weight and adiposity on inflammatory cytokine responses in old horses.
Adams AA, Katepalli MP, Kohler K, Reedy SE, Stilz JP, Vick MM, Fitzgerald BP, Lawrence LM, Horohov DW.
"Reducing body weight and fat in old horses significantly reduced the percent of IFNgamma and TNFalpha positive lymphocytes and monocytes, and serum levels of TNFalpha protein. Further, when weight and fat increased in these old horses there was a significant increase in inflammatory cytokine production." "These findings demonstrate that age-related obesity potentially plays a role in the dysregulation of inflammatory cytokine production by the immune system with age or inflamm-aging in the horse."
Johnson PJ, Wiedmeyer CE, Messer NT, Ganjam VK
Medical Implications of Obesity in Horses—Lessons for Human Obesity
J Diabetes Sci Technol. 2009 January; 3(1): 163–174 (Full)
Carter RA, McCutcheon LJ, George LA, Smith TL, Frank N, Geor RJ
Effects of diet-induced weight gain on insulin sensitivity and plasma hormone and lipid concentrations in horses
Am J Vet Res. 2009 Oct;70(10):1250-8 (PubMed)
"Diet-induced weight gain in horses occurred concurrently with decreased insulin sensitivity that was effectively compensated for by an increase in insulin secretory response. Obesity resulted in hyperinsulinemia and hyperleptinemia"
Carter RA, PhD dissertation 2008
Equine Obesity and its role in insulin resistance, inflammation and risk for laminitis
JAVMA, Vol 228, No. 9, May 1, 2006
Physical characteristics, blood hormone concentrations, and plasma lipid concentrations in obese horses with insulin resistance.
Frank N, Elliott SB, Brandt LE, Keisler DH
J ANIM SCI September 2003 vol. 81 no. 9 2333-2342
Obesity and diet affect glucose dynamics and insulin sensitivity in Thoroughbred geldings
Hoffman RM, Boston RC, Stefanovski D, Kronfeld DS, Harris PA
The Sg was higher in obese than nonobese (P = 0.003) and moderately obese (P = 0.007) horses; Si was lower in obese than nonobese (P = 0.008) horses, and acute insulin response to glucose was higher in obese than nonobese (P = 0.039) horses.Obese geldings were insulin-resistant and seemed to rely primarily on Sg for glucose disposal.
Is using a weight tape accurate?
Hoffmann G, Bentke A, Rose-Meierhöfer S, Ammon C, Mazetti P, Hardarson GH
Estimation of the Body Weight of Icelandic Horses
Journal of Equine Veterinary Science Article in press published online 28 Feb 2013
This research concluded that estimating the body weight of Icelandic horses using either a weight tape or calculation from the measurement of body girth and length was comparable to weighing the horse on a weighbridge (94% and 93% accurate respectively).
How prevalent is obesity in horses?
Robin CA, Ireland JL, Wylie CE, Collins SN, Verheyen KL, Newton JR
Prevalence of and risk factors for equine obesity in Great Britain based on owner-reported body condition scores
Equine Vet J. 2015 Mar;47(2):196-201. doi: 10.1111/evj.12275. Epub 2014 May 23
31.2% of horses were classified as obese by owners in Great Britain selected to complete a postal questionnaire (no experienced verification of owner scores appears to have been carried out).
Giles SL, Rands SA, Nicol CJ, Harris PA
Obesity prevalence and associated risk factors in outdoor living domestic horses and ponies
PeerJ. 2014 Mar 20;2:e299"Obesity prevalence rose significantly from 27.08% at the end of winter to 35.41% during summer (p < 0.001). Breed was the risk factor most strongly associated with obesity."
Thatcher CD, Pleasant RS, Geor RJ, Elvinger F
Prevalence of overconditioning in mature horses in southwest Virginia during the summer
J Vet Intern Med. 2012 Nov-Dec;26(6):1413-8 (PubMed)
See also: Journal of Animal Physiology and Animal Nutrition Volume 92, Issue 2, page 222, April 2008
Stephenson HM, Green MJ, Freeman SL
Prevalence of obesity in a population of horses in the UK
Veterinary Record 2011 168, 131
For more details about the above (Thatcher et al.) study, see:
Equine Endocrine Disease: Cushings and Equine Metabolic Syndrome - Dr. Martin Furr Dip ACVIM, PhD, Adelaide C Riggs Professor of Medicine
Effects of obesity
Nostell K, Lindåse S, Winqvist E, Bröjer J.
The effect of diet-induced obesity and pasture on blood pressure and serum cortisol in Standardbred mares.
Equine Vet J. 2021 May;53(3):542-548. doi: 10.1111/evj.13294. Epub 2020 Jul 4. PMID: 32483866.
Keywords: EHC; blood pressure; cortisol; horse; obesity.
Obesity was associated with a linear increase in blood pressure and an increase in serum cortisol that was not associated with insulin sensitivity
Banse HE, Holbrook TC, Frank N, McFarlane D
Relationship of skeletal muscle inflammation with obesity and obesity-associated hyperinsulinemia in horses
Can J Vet Res. 2016 Jul;80(3):217-24
"In horses, neither skeletal muscle nor systemic inflammation appears to be positively related to obesity or obesity-associated hyperinsulinemia."
Banse HE, Frank N, Kwong GP, McFarlane D
Relationship of oxidative stress in skeletal muscle with obesity and obesity-associated hyperinsulinemia in horses
Can J Vet Res. 2015 Oct;79(4):329-38 (PubMed)
"In conclusion, although oxidative stress in skeletal muscle appears to occur with equine obesity, oxidative damage does not appear to be associated with obesity and is therefore unlikely to be central to obesity-associated hyperinsulinemia."
Siegers EW, de Ruijter-Villani M, van Doorn DA, Stout TAE, Roelfsema E
Ultrasonographic measurements of localized fat accumulation in Shetland pony mares fed a normal v. a high energy diet for 2 years
Animal. 2017 Dec 4:1-9. doi: 10.1017/S1751731117003251. [Epub ahead of print
Shetland ponies fed double maintenance requirements (200% net energy) showed significant increases in body weight, body condition score, and retroperitoneal, axillary, withers, intercostal and rump fat depth, compared to controls (100% net energy).
"The conclusions were that a 200% NE diet induced subcutaneous and retroperitoneal fat accumulation, with the greatest increase in intra-abdominal deposits. The moderate increase of the subcutaneous fat depth followed by a plateau phase suggests the existence of a limit of adipose tissue expandability, as in man."
Bruynsteen L, Erkens T, Peelman LJ, Ducatelle R, Janssens GPJ, Harris PA, Hesta M
Expression of inflammation-related genes is associated with adipose tissue location in horses
BMC Veterinary Research Dec 2013 9:240 https://doi.org/10.1186/1746-6148-9-240
Body Condition Scores - The Henneke System - www.gerlltd.org
Equine Body Condition Score - www.thehorse.com
Research and articles:
Furtado T, Perkins E, Pinchbeck G, McGowan C, Watkins F, Christley R
Exploring horse owners’ understanding of obese body condition and weight management in UK leisure horses
Equine Vet Journal published online 01 October 2020. doi.org/10.1111/evj.13360
Knowles EJ, Grieve L
Clinical insights: Equine obesity
EVJ Sept 2020 52,5 635-638. Published online 04 August 2020. https://doi.org/10.1111/evj.13307
Furtado, Tamzin
Exploring the recognition and management of obesity in horses through qualitative research
PhD thesis Liverpool University May 2019
Equine obesity: the most common risk factor for laminitis in the UK? David Rendle, Pat Harris, Nicola Menzies-Gow, Veterinary Times Nov 2019 (file)
Rendle D, McGregor Argo C, Bowen M, Carslake H, German A, Harris P, Knowles E, Menzies-Gow N, Morgan R
Equine obesity: current perspectives
UK-Vet Equine Sept/Oct 2018 Vol 2 No 5
Morrison, Philippa K
Equine Obesity: Concepts and Mechanisms
PhD thesis University of Liverpool Sept 2015
Robin CA, Ireland JL, Wylie CE, Collins SN, Verheyen KLP, Newton JR
Prevalence of and risk factors for equine obesity in Great Britain based on owner-reported body condition scores
EVJ March 2015 47, 2 196-201. First published online 16 April 2014 and in full online 04 August 2020. https://doi.org/10.1111/evj.12275
Vet J. 2012 Nov;194(2):179-88. Epub 2012 Oct 30.
Weight loss resistance: a further consideration for the nutritional management of obese Equidae.
Argo CM, Curtis GC, Grove-White D, Dugdale AH, Barfoot CF, Harris PA.
7th International Equitation Science Conference 27th-29th October 2011 Conference Proceedings Session 05 Poster 25
Variation in body condition in small groups of horses
Giles S, Harris PA, Nicol CI, Rands SA
More than 27% of 127 horses and ponies in Somerset were found to be obese (assessed using BCS and CNS) in February.
The difference in body condition score between members of the same herd was questioned.
Dugdale, Alex (2011), Doctoral thesis, University of Liverpool.
Aspects of adiposity in ponies
Dugdale AH, Curtis GC, Harris PA, Argo CM.
Assessment of body fat in the pony: part I. Relationships between the anatomical distribution of adipose tissue, body composition and body condition.
Equine Vet J. 2011 Sep;43(5):552-61.
Vet Immunol Immunopathol. 2009 Feb 15;127(3-4):286-94. Epub 2008 Oct 31. (PubMed)
Effect of body condition, body weight and adiposity on inflammatory cytokine responses in old horses.
Adams AA, Katepalli MP, Kohler K, Reedy SE, Stilz JP, Vick MM, Fitzgerald BP, Lawrence LM, Horohov DW.
"Reducing body weight and fat in old horses significantly reduced the percent of IFNgamma and TNFalpha positive lymphocytes and monocytes, and serum levels of TNFalpha protein. Further, when weight and fat increased in these old horses there was a significant increase in inflammatory cytokine production." "These findings demonstrate that age-related obesity potentially plays a role in the dysregulation of inflammatory cytokine production by the immune system with age or inflamm-aging in the horse."
Johnson PJ, Wiedmeyer CE, Messer NT, Ganjam VK
Medical Implications of Obesity in Horses—Lessons for Human Obesity
J Diabetes Sci Technol. 2009 January; 3(1): 163–174 (Full)
Carter RA, McCutcheon LJ, George LA, Smith TL, Frank N, Geor RJ
Effects of diet-induced weight gain on insulin sensitivity and plasma hormone and lipid concentrations in horses
Am J Vet Res. 2009 Oct;70(10):1250-8 (PubMed)
"Diet-induced weight gain in horses occurred concurrently with decreased insulin sensitivity that was effectively compensated for by an increase in insulin secretory response. Obesity resulted in hyperinsulinemia and hyperleptinemia"
Carter RA, PhD dissertation 2008
Equine Obesity and its role in insulin resistance, inflammation and risk for laminitis
JAVMA, Vol 228, No. 9, May 1, 2006
Physical characteristics, blood hormone concentrations, and plasma lipid concentrations in obese horses with insulin resistance.
Frank N, Elliott SB, Brandt LE, Keisler DH
J ANIM SCI September 2003 vol. 81 no. 9 2333-2342
Obesity and diet affect glucose dynamics and insulin sensitivity in Thoroughbred geldings
Hoffman RM, Boston RC, Stefanovski D, Kronfeld DS, Harris PA
The Sg was higher in obese than nonobese (P = 0.003) and moderately obese (P = 0.007) horses; Si was lower in obese than nonobese (P = 0.008) horses, and acute insulin response to glucose was higher in obese than nonobese (P = 0.039) horses.Obese geldings were insulin-resistant and seemed to rely primarily on Sg for glucose disposal.
Is using a weight tape accurate?
Hoffmann G, Bentke A, Rose-Meierhöfer S, Ammon C, Mazetti P, Hardarson GH
Estimation of the Body Weight of Icelandic Horses
Journal of Equine Veterinary Science Article in press published online 28 Feb 2013
This research concluded that estimating the body weight of Icelandic horses using either a weight tape or calculation from the measurement of body girth and length was comparable to weighing the horse on a weighbridge (94% and 93% accurate respectively).
How prevalent is obesity in horses?
Robin CA, Ireland JL, Wylie CE, Collins SN, Verheyen KL, Newton JR
Prevalence of and risk factors for equine obesity in Great Britain based on owner-reported body condition scores
Equine Vet J. 2015 Mar;47(2):196-201. doi: 10.1111/evj.12275. Epub 2014 May 23
31.2% of horses were classified as obese by owners in Great Britain selected to complete a postal questionnaire (no experienced verification of owner scores appears to have been carried out).
Giles SL, Rands SA, Nicol CJ, Harris PA
Obesity prevalence and associated risk factors in outdoor living domestic horses and ponies
PeerJ. 2014 Mar 20;2:e299"Obesity prevalence rose significantly from 27.08% at the end of winter to 35.41% during summer (p < 0.001). Breed was the risk factor most strongly associated with obesity."
Thatcher CD, Pleasant RS, Geor RJ, Elvinger F
Prevalence of overconditioning in mature horses in southwest Virginia during the summer
J Vet Intern Med. 2012 Nov-Dec;26(6):1413-8 (PubMed)
See also: Journal of Animal Physiology and Animal Nutrition Volume 92, Issue 2, page 222, April 2008
Stephenson HM, Green MJ, Freeman SL
Prevalence of obesity in a population of horses in the UK
Veterinary Record 2011 168, 131
For more details about the above (Thatcher et al.) study, see:
Equine Endocrine Disease: Cushings and Equine Metabolic Syndrome - Dr. Martin Furr Dip ACVIM, PhD, Adelaide C Riggs Professor of Medicine
Effects of obesity
Nostell K, Lindåse S, Winqvist E, Bröjer J.
The effect of diet-induced obesity and pasture on blood pressure and serum cortisol in Standardbred mares.
Equine Vet J. 2021 May;53(3):542-548. doi: 10.1111/evj.13294. Epub 2020 Jul 4. PMID: 32483866.
Keywords: EHC; blood pressure; cortisol; horse; obesity.
Obesity was associated with a linear increase in blood pressure and an increase in serum cortisol that was not associated with insulin sensitivity
Banse HE, Holbrook TC, Frank N, McFarlane D
Relationship of skeletal muscle inflammation with obesity and obesity-associated hyperinsulinemia in horses
Can J Vet Res. 2016 Jul;80(3):217-24
"In horses, neither skeletal muscle nor systemic inflammation appears to be positively related to obesity or obesity-associated hyperinsulinemia."
Banse HE, Frank N, Kwong GP, McFarlane D
Relationship of oxidative stress in skeletal muscle with obesity and obesity-associated hyperinsulinemia in horses
Can J Vet Res. 2015 Oct;79(4):329-38 (PubMed)
"In conclusion, although oxidative stress in skeletal muscle appears to occur with equine obesity, oxidative damage does not appear to be associated with obesity and is therefore unlikely to be central to obesity-associated hyperinsulinemia."
Siegers EW, de Ruijter-Villani M, van Doorn DA, Stout TAE, Roelfsema E
Ultrasonographic measurements of localized fat accumulation in Shetland pony mares fed a normal v. a high energy diet for 2 years
Animal. 2017 Dec 4:1-9. doi: 10.1017/S1751731117003251. [Epub ahead of print
Shetland ponies fed double maintenance requirements (200% net energy) showed significant increases in body weight, body condition score, and retroperitoneal, axillary, withers, intercostal and rump fat depth, compared to controls (100% net energy).
"The conclusions were that a 200% NE diet induced subcutaneous and retroperitoneal fat accumulation, with the greatest increase in intra-abdominal deposits. The moderate increase of the subcutaneous fat depth followed by a plateau phase suggests the existence of a limit of adipose tissue expandability, as in man."
Bruynsteen L, Erkens T, Peelman LJ, Ducatelle R, Janssens GPJ, Harris PA, Hesta M
Expression of inflammation-related genes is associated with adipose tissue location in horses
BMC Veterinary Research Dec 2013 9:240 https://doi.org/10.1186/1746-6148-9-240
Oligofructose
See also Fructans
Oligofructose is a partial hydrolysate of inulin.
Oligofructose has been shown to induce laminitis at 7.5 g/kg bwt via nasogastric tube:
Jiang R, Gao L, Wang G, Li X, Li Y, Fa X
Role of insulin during the development of oligofructose (OF)-induced equine laminitis
Bull Vet Inst Pulawy 59, 303-309, July 2015
9/11 horses given 10 g/kg bw oligofructose developed at least Obel grade 2 laminitis. 11/11 of these horses developed profuse watery diarrhoea between 12 and 24 hours after being given the OF by naso-gastric tube. Interestingly the laminitis appeared to be self-limiting, with 7 of the 9 horses that developed laminitis returning to being pain free 72 hours after being given OF.
(Note that the oligofructose used is unlikely to have been pure, and that simple sugars are also likely to be included. Beneo Orafti oligofructose is available in purity ranging from 58-95%, with the balance being sugar. Therefore when given at 10 g/kg bw, even at 95% purity a 500 kg horse would receive 4750 g of oligofructose and 250 g of sugar. To put this into perspective, 250 g is more than 3 times the amount of sugar used in the Oral Sugar Test, so might be expected to produce an insulin response).
Equine Vet J. 2011 Nov;43(6):737-43. doi: 10.1111/j.2042-3306.2010.00336.x. Epub 2011 Mar 15. (PubMed)
Nuclear magnetic resonance-based metabonomic study of early time point laminitis in an oligofructose-overload model
Keller MD, Pollitt CC, Marx UC
"oligofructose, a carbohydrate usually considered indigestible in the small intestine, or derivatives of oligofructose, was detected in plasma."
ISME J. 2008 Nov;2(11):1089-100.
Microbial ecology of the equine hindgut during oligofructose-induced laminitis.
Milinovich GJ, Burrell PC, Pollitt CC, Klieve AV, Blackall LL, Ouwerkerk D, Woodland E, Trott DJ.
Int J Syst Evol Microbiol. 2008 Jan;58(Pt 1):262-6.
Streptococcus henryi sp. nov. and Streptococcus caballi sp. nov., isolated from the hindgut of horses with oligofructose-induced laminitis.
Milinovich GJ, Burrell PC, Pollitt CC, Bouvet A, Trott DJ.
Milinovich GJ, Trott DJ, Burrell PC, van Eps AW, Thoefner MB, Blackall LL, Al Jassim RA, Morton JM, Pollitt CC.
Changes in equine hindgut bacterial populations during oligofructose-induced laminitis.
Environ Microbiol. 2006 May;8(5):885-98.
Oligofructose is a partial hydrolysate of inulin.
Oligofructose has been shown to induce laminitis at 7.5 g/kg bwt via nasogastric tube:
Jiang R, Gao L, Wang G, Li X, Li Y, Fa X
Role of insulin during the development of oligofructose (OF)-induced equine laminitis
Bull Vet Inst Pulawy 59, 303-309, July 2015
9/11 horses given 10 g/kg bw oligofructose developed at least Obel grade 2 laminitis. 11/11 of these horses developed profuse watery diarrhoea between 12 and 24 hours after being given the OF by naso-gastric tube. Interestingly the laminitis appeared to be self-limiting, with 7 of the 9 horses that developed laminitis returning to being pain free 72 hours after being given OF.
(Note that the oligofructose used is unlikely to have been pure, and that simple sugars are also likely to be included. Beneo Orafti oligofructose is available in purity ranging from 58-95%, with the balance being sugar. Therefore when given at 10 g/kg bw, even at 95% purity a 500 kg horse would receive 4750 g of oligofructose and 250 g of sugar. To put this into perspective, 250 g is more than 3 times the amount of sugar used in the Oral Sugar Test, so might be expected to produce an insulin response).
Equine Vet J. 2011 Nov;43(6):737-43. doi: 10.1111/j.2042-3306.2010.00336.x. Epub 2011 Mar 15. (PubMed)
Nuclear magnetic resonance-based metabonomic study of early time point laminitis in an oligofructose-overload model
Keller MD, Pollitt CC, Marx UC
"oligofructose, a carbohydrate usually considered indigestible in the small intestine, or derivatives of oligofructose, was detected in plasma."
ISME J. 2008 Nov;2(11):1089-100.
Microbial ecology of the equine hindgut during oligofructose-induced laminitis.
Milinovich GJ, Burrell PC, Pollitt CC, Klieve AV, Blackall LL, Ouwerkerk D, Woodland E, Trott DJ.
Int J Syst Evol Microbiol. 2008 Jan;58(Pt 1):262-6.
Streptococcus henryi sp. nov. and Streptococcus caballi sp. nov., isolated from the hindgut of horses with oligofructose-induced laminitis.
Milinovich GJ, Burrell PC, Pollitt CC, Bouvet A, Trott DJ.
Milinovich GJ, Trott DJ, Burrell PC, van Eps AW, Thoefner MB, Blackall LL, Al Jassim RA, Morton JM, Pollitt CC.
Changes in equine hindgut bacterial populations during oligofructose-induced laminitis.
Environ Microbiol. 2006 May;8(5):885-98.
Omega 3
Hess TM, Rexford J, Hansen DK, Ahrens NS, Harris M, Engle T, Ross T, Allen KG
Effects of Ω-3 (n-3) Fatty Acid Supplementation on Insulin Sensitivity in Horses
Journal of Equine Veterinary Science 2013, Volume 33 , Issue 6 , 446 - 453
"In insulin-resistant mares, MARINE- and FLAX-treated horses had an increase in SI (P = .09). It would be interesting to test this supplement in a larger group of insulin-resistant horses. If proven effective, supplementation with ω-3 fatty acids would help to reduce problems associated with insulin resistance in horses."
Can Fatty Acid Supplementation Help IR Horses? - Kristen M Janicki www.thehorse.com Aug 2013
Hess T, Ross-Jones T
Omega-3 fatty acid supplementation in horses
R. Bras. Zootec. vol.43 no.12 Viçosa Dec. 2014
Jill Kristen Rexford MSc thesis 2010
Effects of two different dietary sources of omega-3 highly unsaturated fatty acids on insulin sensitivity, and incorporation into the plasma, red blood cell, and muscle cell in horses.
Hess TM, Rexford J, Hansen DK, Ahrens NS, Harris M, Engle T, Ross T, Allen KG
Effects of Ω-3 (n-3) Fatty Acid Supplementation on Insulin Sensitivity in Horses
Journal of Equine Veterinary Science 2013, Volume 33 , Issue 6 , 446 - 453
"In insulin-resistant mares, MARINE- and FLAX-treated horses had an increase in SI (P = .09). It would be interesting to test this supplement in a larger group of insulin-resistant horses. If proven effective, supplementation with ω-3 fatty acids would help to reduce problems associated with insulin resistance in horses."
Can Fatty Acid Supplementation Help IR Horses? - Kristen M Janicki www.thehorse.com Aug 2013
Hess T, Ross-Jones T
Omega-3 fatty acid supplementation in horses
R. Bras. Zootec. vol.43 no.12 Viçosa Dec. 2014
Jill Kristen Rexford MSc thesis 2010
Effects of two different dietary sources of omega-3 highly unsaturated fatty acids on insulin sensitivity, and incorporation into the plasma, red blood cell, and muscle cell in horses.
OST (Oral Sugar Test)/In Feed Glucose Test
As endocrinopathic laminitis in horses is associated with high blood insulin levels after eating sugar (particularly in grass), oral sugar testing (using either Karo Light corn syrup or glucose) has become a popular method of testing a horse's insulin response to a controlled amount of sugar, attempting to mimic the effects of grazing, and thereby guiding management of and monitoring laminitis risk for horses with insulin dysregulation due to EMS and/or PPID.
The in-feed glucose test has lost popularity due to problems with horses either not eating or slowly eating the large amount of glucose mixed into a low sugar feed, and since October 2013 the oral sugar test (OST) has been the recommended test to assess insulin status in horses with PPID (according to the Equine Endocrinology Group), and from 2018 it has been the test recommended by Liphook Equine Hospital, who state that the OST has significant advantages over the in-feed glucose test.
The protocol of the OST has changed several times, with 0.15 ml/kg bodyweight Karo Light corn syrup originally being administered after an overnight fast, then research at the RVC and Liphook Equine Hospital suggested that a higher dose of 0.45 ml/kg gave more accurate results, with horses not needing to be fasted before the test, and most recently the same 0.45 ml/kg dose is being suggested (by Liphook Equine Hospital), but once again after an overnight fast. The horse is given the Karo Light corn syrup by syringe or mixed with a small amount of low sugar chaff, and the vet draws a sample of blood 60 to 90 (or 120) minutes later.
Some experts warn that the OST and in-feed glucose test should not be carried out while or soon after a horse has shown signs of active laminitis, as sugar levels should be kept to a minimum.
The in-feed glucose test has lost popularity due to problems with horses either not eating or slowly eating the large amount of glucose mixed into a low sugar feed, and since October 2013 the oral sugar test (OST) has been the recommended test to assess insulin status in horses with PPID (according to the Equine Endocrinology Group), and from 2018 it has been the test recommended by Liphook Equine Hospital, who state that the OST has significant advantages over the in-feed glucose test.
The protocol of the OST has changed several times, with 0.15 ml/kg bodyweight Karo Light corn syrup originally being administered after an overnight fast, then research at the RVC and Liphook Equine Hospital suggested that a higher dose of 0.45 ml/kg gave more accurate results, with horses not needing to be fasted before the test, and most recently the same 0.45 ml/kg dose is being suggested (by Liphook Equine Hospital), but once again after an overnight fast. The horse is given the Karo Light corn syrup by syringe or mixed with a small amount of low sugar chaff, and the vet draws a sample of blood 60 to 90 (or 120) minutes later.
Some experts warn that the OST and in-feed glucose test should not be carried out while or soon after a horse has shown signs of active laminitis, as sugar levels should be kept to a minimum.
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Oral Sugar Test
The current (2018) protocol for the OST suggested by Liphook Equine Hospital: The Karo Light Syrup Oral Sugar Test - LEH 2018 1. Withhold feed for 3-8 hours beforehand (e.g. allow 1 slab of hay overnight) 2. OPTIONAL: Collect baseline blood sample for insulin (red top tube) 3. Administer Karo Light Corn Syrup at a dose of 45 mL per 100 kg bodyweight, either by dosing syringe or in a little chaff. 4. Collect blood samples for insulin and glucose (red and grey top tubes) at some point between 60 – 90 minutes post-dosing Other laboratories may recommend the earlier protocol: The horse is fasted overnight (as above - 1 flake of hay only left in the stable at/after 10 pm). The following morning the owner administers 0.15 ml/kg bodyweight Karo Light corn syrup (containing 1 g/ml digestible sugar - i.e. 75 ml/500 kg horse) - this can be syringed directly into the horse's mouth (using 60 ml catheter-tip syringes) (or fed in a low calorie chaff feed). 60 to 90 minutes after administration of the corn syrup blood is collected by the vet and tested for insulin and glucose. Insulin > 60 µIU/ml is indicative of insulin resistance/hyperinsulinaemia. Insulin < 45 µIU/ml is normal. Insulin between 45 and 60 µIU/ml is an equivocal result and further testing is required for diagnosis. Glucose > 125 mg/dl (6.94 mmol/l) indicates an excessive glucose response. See Recommendations for the Diagnosis and Treatment of Equine Metabolic Syndrome (EMS) - Equine Endocrinology Group 2016 |
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Macon EL, Harris P, Partridge E, Barker VD, Adams A
Effect of dose and fasting on oral sugar test responses in insulin dysregulated horses
JEVS published online 16 September 2021 https://doi.org/10.1016/j.jevs.2021.103770
Keywords: Insulin dysregulation, oral sugar test, Equine Metabolic Syndrome, varying oral sugar dose, fasting duration
In July 2017 Liphook Equine Hospital announced:
"Karo Light Corn Syrup test for assessment of insulin dysregulation
Recent work at the Royal Vet College and at Liphook Equine Hospital supports the use of a higher dose of Karo Light corn syrup as a highly palatable, safe and sensitive test for the investigation of insulin dysregulation in PPID and EMS cases.
In addition to good differentiation of normal from laminitis-prone horses and ponies, the test dose contains less than half the amount of sugar that the 1g/kg dextrose powder test. There is also no need to fast the animal prior to the test and the syrup is much easier to administer to horses and ponies that the dextrose powder!
Procedure:
- Baseline insulin and glucose samples are optional
- Give 45mL Karo Light Corn Syrup per 100 kg bodyweight either by dosing syringe or in a small amount of chaff
- Collect blood samples for insulin and glucose (red and grey top) between 60 and 90 minutes later."
Liphook Equine Hospital Laboratory can send out Karo Light test kits containing: Karo Light Corn Syrup dose (please advise weight of animal), oral dosing syringe and appropriate blood collection tubes. Please feel free to phone (01428 729509) or email: lab@theleh.co.uk for more information on these and other handy, free testing kits."
Karo Light corn syrup can be purchased in the UK online from www.amazon.co.uk, and costs around £5.70 for 473 ml (a 500 kg horse will require 0.45 ml x 500 kg = 225 ml Karo Light corn syrup for the high dose test, and 0.15 ml x 500 kg = 75 ml for the low dose test), and can also be supplied to vets by Liphook Equine Hospital.
The increased dose of Karo Light corn syrup is based on this research:
Jocelyn NA, Harris PA, Menzies-Gow NJ
Effect of Varying the Dose of Karo Light Syrup on the Insulin Response to the Oral Sugar Test
Equine Veterinary Journal Volume 49, Issue S51 September 2017 Page 25
More details:
EEG Recommendations for the Diagnosis and Treatment of PPID
Nicholas Frank's webcast from the University of Minnesota: EMS and ponies - Dr Nicholas Frank - 18 Oct 2011
The Oral Sugar Test uses significantly lower carbohydrate levels (0.15 g/kg bw) than the in-feed glucose test (1 or 0.5 g/kg bw) and therefore is likely to cause a smaller insulin peak. For this reason The Laminitis Site recommends the use of the (low dose) Oral Sugar Test over the in-feed glucose test.
Effect of dose and fasting on oral sugar test responses in insulin dysregulated horses
JEVS published online 16 September 2021 https://doi.org/10.1016/j.jevs.2021.103770
Keywords: Insulin dysregulation, oral sugar test, Equine Metabolic Syndrome, varying oral sugar dose, fasting duration
In July 2017 Liphook Equine Hospital announced:
"Karo Light Corn Syrup test for assessment of insulin dysregulation
Recent work at the Royal Vet College and at Liphook Equine Hospital supports the use of a higher dose of Karo Light corn syrup as a highly palatable, safe and sensitive test for the investigation of insulin dysregulation in PPID and EMS cases.
In addition to good differentiation of normal from laminitis-prone horses and ponies, the test dose contains less than half the amount of sugar that the 1g/kg dextrose powder test. There is also no need to fast the animal prior to the test and the syrup is much easier to administer to horses and ponies that the dextrose powder!
Procedure:
- Baseline insulin and glucose samples are optional
- Give 45mL Karo Light Corn Syrup per 100 kg bodyweight either by dosing syringe or in a small amount of chaff
- Collect blood samples for insulin and glucose (red and grey top) between 60 and 90 minutes later."
Liphook Equine Hospital Laboratory can send out Karo Light test kits containing: Karo Light Corn Syrup dose (please advise weight of animal), oral dosing syringe and appropriate blood collection tubes. Please feel free to phone (01428 729509) or email: lab@theleh.co.uk for more information on these and other handy, free testing kits."
Karo Light corn syrup can be purchased in the UK online from www.amazon.co.uk, and costs around £5.70 for 473 ml (a 500 kg horse will require 0.45 ml x 500 kg = 225 ml Karo Light corn syrup for the high dose test, and 0.15 ml x 500 kg = 75 ml for the low dose test), and can also be supplied to vets by Liphook Equine Hospital.
The increased dose of Karo Light corn syrup is based on this research:
Jocelyn NA, Harris PA, Menzies-Gow NJ
Effect of Varying the Dose of Karo Light Syrup on the Insulin Response to the Oral Sugar Test
Equine Veterinary Journal Volume 49, Issue S51 September 2017 Page 25
More details:
EEG Recommendations for the Diagnosis and Treatment of PPID
Nicholas Frank's webcast from the University of Minnesota: EMS and ponies - Dr Nicholas Frank - 18 Oct 2011
The Oral Sugar Test uses significantly lower carbohydrate levels (0.15 g/kg bw) than the in-feed glucose test (1 or 0.5 g/kg bw) and therefore is likely to cause a smaller insulin peak. For this reason The Laminitis Site recommends the use of the (low dose) Oral Sugar Test over the in-feed glucose test.
Glucose and insulin concentrations for normal horses and Insulin Resistant horses following administration of 0.15 ml/kg bw Karo Light syrup (data Nicholas Frank webcast Oct 2011 University of Minnesota).
In-feed glucose test/oral glucose test (OGT)
Protocol for the in-feed glucose test suggested by Liphook Equine Hospital:
The horse should be fasted overnight (at least 6 hours).
Feed 0.5 or 1.0 g/kg bodyweight glucose or dextrose (i.e. 250 g or 500 g/500 kg horse) in a low NSC feed, e.g. chaff, the following morning
Collect blood 2 hours later and measure serum insulin and plasma glucose.
For 1.0 g/kg bw glucose, insulin < 87 µIU/ml is considered normal
For 0.5 g/kg bw glucose, insulin < 57 µIU/ml is considered normal
See Diagnosis of Equine Metabolic Syndrome - Liphook Equine Hospital
Protocol for the in-feed glucose test suggested by Liphook Equine Hospital:
The horse should be fasted overnight (at least 6 hours).
Feed 0.5 or 1.0 g/kg bodyweight glucose or dextrose (i.e. 250 g or 500 g/500 kg horse) in a low NSC feed, e.g. chaff, the following morning
Collect blood 2 hours later and measure serum insulin and plasma glucose.
For 1.0 g/kg bw glucose, insulin < 87 µIU/ml is considered normal
For 0.5 g/kg bw glucose, insulin < 57 µIU/ml is considered normal
See Diagnosis of Equine Metabolic Syndrome - Liphook Equine Hospital
From Liphook's Diagnosis of Equine Metabolic Syndrome (Sept 2012)
http://liphookequinehospital.co.uk/wp-content/uploads/Lab-Book-EMS.pdf
Below - note the high median peak insulin concentrations recorded in research by Borer et al. (2012) when 1 g/kg bodyweight glucose was fed to previously laminitic ponies in a feed of Happy Hoof (and note how much the Happy Hoof (control) raised insulin levels above baseline (hay) - more.
As with screening tests, pain, stress and recent feeding will affect results and should be avoided.
Dr Don Walsh of the Animal Health Foundation, talking about the 2012 Equine Endocrinology Summit held in Boston in September, said:
"One of the most widely agreed upon ideas, regarding a diagnosis of EMS, was the use of an oral sugar test to reveal an abnormally large insulin and or glucose response seen in the blood measured 75 minutes after an oral dose of sugar is given." See article on AHF website.
Interestingly it has been known since at least 1986 that ponies that have previously had laminitis show a greater insulin response to glucose:
Equine Vet J. 1986 Mar;18(2):97-101
Glucose tolerance and insulin sensitivity in ponies and Standardbred horses
Jeffcott LB, Field JR, McLean JG, O'Dea K
Research - oral sugar test/in-feed glucose test
Macon EL, Harris P, Barker VD, Adams AA
Seasonal Insulin Responses to the Oral Sugar Test in Healthy and Insulin Dysregulated Horses
Journal of Equine Veterinary Science June 2022 Vol 113. https://doi.org/10.1016/j.jevs.2022.103945
Keywords: Insulin dysregulation, season, metabolic syndrome, NSC, OST
Macon, Erica Lyn
Effects of Season and Nutrition on Insulinemic Responses in Insulin Dysregulated Horses
PhD dissertation August 2021 University of Kentucky. https://uknowledge.uky.edu/gluck_etds/52
Macon EL, Harris P, Partridge E, Barker VD, Adams A
Effect of dose and fasting on oral sugar test responses in insulin dysregulated horses
JEVS published online 16 September 2021 https://doi.org/10.1016/j.jevs.2021.103770
Keywords: Insulin dysregulation, oral sugar test, Equine Metabolic Syndrome, varying oral sugar dose, fasting duration
Macon E, Harris PA, Barker VD, Elzinga S, Adams AA
Insulin Dysregulated and Healthy Horses' Seasonal Insulin Responses to the oral sugar test (OST)
Equine Science Symposium June 2019 (available on ResearchGate)
Hodge E, Kowalski A, Torcivia C, Lindborg S, Stefanovski D, Hart K, Frank N, van Eps A
Effect of thyrotropin-releasing hormone stimulation testing on the oral sugar test in horses when performed as a combined protocol
J Vet Intern Med. 2019 Sep;33(5):2272-2279. doi: 10.1111/jvim.15601. Epub 2019 Aug 20
"The results of this study support the use of combined testing for PPID and ID by performing the TRH stimulation test before the OST, although further validation of these findings in a cohort of horses with confirmed PPID and ID is recommended."
Warnken T, Delarocque J, Schumacher S, Huber K, Feige K
Retrospective analysis of insulin responses to standard dosed oral glucose tests (OGTs) via naso-gastric tubing towards definition of an objective cut-off value
Acta Vet Scand. 2018 Jan 19;60(1):4. doi: 10.1186/s13028-018-0358-8
Meier AD, de Laat MA, Reiche DB, Pollitt CC, Walsh DM, McGree JM, Sillence MNDomest Anim
The oral glucose test predicts laminitis risk in ponies fed a diet high in nonstructural carbohydrates
Endocrinol. 2017 Nov 16;63:1-9. doi: 10.1016/j.domaniend.2017.10.008
Cantarelli C, Dau SL, Stefanello S, Azevedo MS, De Bastiani GR, Palma HE, Brass KE, De La Côrte FD
Evaluation of oral sugar test response for detection of equine metabolic syndrome in obese Crioulo horses
Domestic Animal Endocrinology 63 (2018) 31–37 doi.org/10.1016/j.domaniend.2017.10.006
Lindåse S, Nostell K, Söder J, Bröjer J
Relationship Between β-cell Response and Insulin Sensitivity in Horses based on the Oral Sugar Test and the Euglycemic Hyperinsulinemic Clamp
Journal of Veterinary Internal Medicine published online Aug 2017. doi: 10.1111/jvim.14799
Frank N, Walsh DM
Repeatability of Oral Sugar Test Results, Glucagon-Like Peptide-1 Measurements, and Serum High-Molecular-Weight Adiponectin Concentrations in Horses
J Vet Intern Med. 2017 Jul;31(4):1178-1187. doi: 10.1111/jvim.14725. Epub 2017 May 24
Knowles EJ, Harris PA, Elliott J, Menzies-Gow NJ
Use of the oral sugar test in ponies when performed with or without prior fasting
Equine Vet J. 2017 Jul;49(4):519-524. doi: 10.1111/evj.12607. Epub 2016 Sep 5
Lindåse S, Nostell K, Bröjer J
A modified oral sugar test for evaluation of insulin and glucose dynamics in horses
Acta Vet Scand. 2016; 58(Suppl 1): 64 Published online 2016 Oct 20. doi: 10.1186/s13028-016-0246-z
de Laat MA, Sillence MN
The repeatability of an oral glucose test in ponies
Equine Vet J. 2017 Mar;49(2):238-243. doi: 10.1111/evj.12579. Epub 2016 May 23
How does the OST compare to other insulin tests?
Bertin FR, de Laat MA
The diagnosis of equine insulin dysregulation
Equine Veterinary Journal Volume 49, Issue 5 September 2017 Pages 570–576
Schuver A, Frank N, Chameroy KA, Elliott SB
Assessment of Insulin and Glucose Dynamics by Using an Oral Sugar Test in Horses
Journal of Equine Veterinary Science published online 04 November 2013
Fasted Oral Sugar Tests (OST) and Intravenous Glucose Tolerance Tests (IVGTT) were carried out on 10 EMS horses and 8 controls (QH crossbred mares).
Area under the curve for glucose was 1.3 x higher for the IVGTT and 1.3 x higher for the OST in the EMS horses, and
Area under the curve for insulin was 9.0 x higher for the IVGTT and 6.8 x higher for the OST in the EMS horses,
suggesting that the OST and IVGTT insulin results are closely correlated and the OST may be a suitable test for insulin dysregulation.
The OST was also repeated in 8 QH crossbred mares - the CV (coefficient of variation) for AUCg was 6.4% +/- 3.1% and the CV for AUCi was 45.1% +/- 36.2% - so there was a large difference in insulin values when the same horse was tested more than once.
Dr Don Walsh of the Animal Health Foundation, talking about the 2012 Equine Endocrinology Summit held in Boston in September, said:
"One of the most widely agreed upon ideas, regarding a diagnosis of EMS, was the use of an oral sugar test to reveal an abnormally large insulin and or glucose response seen in the blood measured 75 minutes after an oral dose of sugar is given." See article on AHF website.
Interestingly it has been known since at least 1986 that ponies that have previously had laminitis show a greater insulin response to glucose:
Equine Vet J. 1986 Mar;18(2):97-101
Glucose tolerance and insulin sensitivity in ponies and Standardbred horses
Jeffcott LB, Field JR, McLean JG, O'Dea K
Research - oral sugar test/in-feed glucose test
Macon EL, Harris P, Barker VD, Adams AA
Seasonal Insulin Responses to the Oral Sugar Test in Healthy and Insulin Dysregulated Horses
Journal of Equine Veterinary Science June 2022 Vol 113. https://doi.org/10.1016/j.jevs.2022.103945
Keywords: Insulin dysregulation, season, metabolic syndrome, NSC, OST
Macon, Erica Lyn
Effects of Season and Nutrition on Insulinemic Responses in Insulin Dysregulated Horses
PhD dissertation August 2021 University of Kentucky. https://uknowledge.uky.edu/gluck_etds/52
Macon EL, Harris P, Partridge E, Barker VD, Adams A
Effect of dose and fasting on oral sugar test responses in insulin dysregulated horses
JEVS published online 16 September 2021 https://doi.org/10.1016/j.jevs.2021.103770
Keywords: Insulin dysregulation, oral sugar test, Equine Metabolic Syndrome, varying oral sugar dose, fasting duration
Macon E, Harris PA, Barker VD, Elzinga S, Adams AA
Insulin Dysregulated and Healthy Horses' Seasonal Insulin Responses to the oral sugar test (OST)
Equine Science Symposium June 2019 (available on ResearchGate)
Hodge E, Kowalski A, Torcivia C, Lindborg S, Stefanovski D, Hart K, Frank N, van Eps A
Effect of thyrotropin-releasing hormone stimulation testing on the oral sugar test in horses when performed as a combined protocol
J Vet Intern Med. 2019 Sep;33(5):2272-2279. doi: 10.1111/jvim.15601. Epub 2019 Aug 20
"The results of this study support the use of combined testing for PPID and ID by performing the TRH stimulation test before the OST, although further validation of these findings in a cohort of horses with confirmed PPID and ID is recommended."
Warnken T, Delarocque J, Schumacher S, Huber K, Feige K
Retrospective analysis of insulin responses to standard dosed oral glucose tests (OGTs) via naso-gastric tubing towards definition of an objective cut-off value
Acta Vet Scand. 2018 Jan 19;60(1):4. doi: 10.1186/s13028-018-0358-8
Meier AD, de Laat MA, Reiche DB, Pollitt CC, Walsh DM, McGree JM, Sillence MNDomest Anim
The oral glucose test predicts laminitis risk in ponies fed a diet high in nonstructural carbohydrates
Endocrinol. 2017 Nov 16;63:1-9. doi: 10.1016/j.domaniend.2017.10.008
Cantarelli C, Dau SL, Stefanello S, Azevedo MS, De Bastiani GR, Palma HE, Brass KE, De La Côrte FD
Evaluation of oral sugar test response for detection of equine metabolic syndrome in obese Crioulo horses
Domestic Animal Endocrinology 63 (2018) 31–37 doi.org/10.1016/j.domaniend.2017.10.006
Lindåse S, Nostell K, Söder J, Bröjer J
Relationship Between β-cell Response and Insulin Sensitivity in Horses based on the Oral Sugar Test and the Euglycemic Hyperinsulinemic Clamp
Journal of Veterinary Internal Medicine published online Aug 2017. doi: 10.1111/jvim.14799
Frank N, Walsh DM
Repeatability of Oral Sugar Test Results, Glucagon-Like Peptide-1 Measurements, and Serum High-Molecular-Weight Adiponectin Concentrations in Horses
J Vet Intern Med. 2017 Jul;31(4):1178-1187. doi: 10.1111/jvim.14725. Epub 2017 May 24
Knowles EJ, Harris PA, Elliott J, Menzies-Gow NJ
Use of the oral sugar test in ponies when performed with or without prior fasting
Equine Vet J. 2017 Jul;49(4):519-524. doi: 10.1111/evj.12607. Epub 2016 Sep 5
Lindåse S, Nostell K, Bröjer J
A modified oral sugar test for evaluation of insulin and glucose dynamics in horses
Acta Vet Scand. 2016; 58(Suppl 1): 64 Published online 2016 Oct 20. doi: 10.1186/s13028-016-0246-z
de Laat MA, Sillence MN
The repeatability of an oral glucose test in ponies
Equine Vet J. 2017 Mar;49(2):238-243. doi: 10.1111/evj.12579. Epub 2016 May 23
How does the OST compare to other insulin tests?
Bertin FR, de Laat MA
The diagnosis of equine insulin dysregulation
Equine Veterinary Journal Volume 49, Issue 5 September 2017 Pages 570–576
Schuver A, Frank N, Chameroy KA, Elliott SB
Assessment of Insulin and Glucose Dynamics by Using an Oral Sugar Test in Horses
Journal of Equine Veterinary Science published online 04 November 2013
Fasted Oral Sugar Tests (OST) and Intravenous Glucose Tolerance Tests (IVGTT) were carried out on 10 EMS horses and 8 controls (QH crossbred mares).
Area under the curve for glucose was 1.3 x higher for the IVGTT and 1.3 x higher for the OST in the EMS horses, and
Area under the curve for insulin was 9.0 x higher for the IVGTT and 6.8 x higher for the OST in the EMS horses,
suggesting that the OST and IVGTT insulin results are closely correlated and the OST may be a suitable test for insulin dysregulation.
The OST was also repeated in 8 QH crossbred mares - the CV (coefficient of variation) for AUCg was 6.4% +/- 3.1% and the CV for AUCi was 45.1% +/- 36.2% - so there was a large difference in insulin values when the same horse was tested more than once.
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Do different breeds appear to have a different insulin response to glucose?
Yes - Bamford NJ, Potter SJ, Harris PA, Bailey SR Breed differences in insulin sensitivity and insulinemic responses to oral glucose in horses and ponies of moderate body condition score Domestic Animal Endocrinology - published online 11 November 2013 |
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Mixed breed ponies, Andalusian cross horses and Standardbred horses, all with a BCS close to 5, were given an in-feed glucose test using 1.5 g/kg bw glucose in a fibre-based feed, and a FSIGT. Glucose results were similar between the breeds following the in-feed glucose test, but there were significant differences in the insulin response to in-feed and IV glucose between the breeds.
Osteomyelitis/Septic Pedal Osteitis - POTENTIALLY LIFE THREATENING
Osteomyelitis/septic pedal osteitis describes infection of the coffin/pedal bone - purulent exudate (pus) will be present. What initially appears to be a "normal" foot abscess may progress to osteomyelitis if the infection does not form a contained abscess, or if an abscess does not resolve and spreads into the coffin/pedal bone. Osteomyelitis of the pedal/coffin bone can follow laminitis with severe rotation/sinking, often after penetration of the sole or long-term abscessing that extends into the bone. Osteomyelitis can also follow penetrating wounds to the foot, or fractures of the pedal/coffin bone.
Osteomyelitis should always be treated as a life threatening emergency. Once infection has invaded the coffin/pedal bone, intense treatment will usually be required, usually in a clinic, involving surgical debridement of the bone and antibiotics. Treating osteomyelitis conservatively greatly decreases the prognosis and increases the risk of supporting limb laminitis in the other feet.
Diagnosis:
If a foot abscess and associated lameness do not respond as quickly as expected, or if discharge continues for longer than expected, osteomyelitis should be considered.
An abscess drainage hole may lead to P3 on clinical examination of the foot.
X-rays, particularly 60' DP views, should be taken, and venograms may help assess blood flow to the infected area.
Treatment is likely to consist of surgery and antibiotics:
Surgery is likely to be required to remove the infected part of the coffin/pedal bone. Surgical debridement of the bone is usually carried out in a clinic, with the horse standing but sedated and local anaesthesia. The ACVS recommends approaching the area of infected bone through the hoof wall (hoof wall resection) rather than through the sole. Following surgery the foot must be kept sterile and then clean.
Antibiotic treatment may be systemic and via regional limb perfusion (RLP), and should be targeted at bacteria identified from bacterial culture of the infected tissue. RLP involves applying a tourniquet to the affected limb and introducing high dose antibiotics below the tourniquet, leading to high levels of antibiotics in the affected tissues. Frequent RLP treatments may be required.
Medical maggot therapy can also be used to debride the necrotic tissue.
Anti-inflammatory and analgesic treatment is likely to be necessary.
See: Subsolar Abscess and Coffin Bone Osteomyelitis - ACVS
Equine Podiatry edited by Andrea Floyd and Richard Mansmann in a chapter written by W Rich Redding p 276 suggests that the infected bone and soft tissue should be debrided and the infection drained, gaining access via the draining tract if possible and being sure to remove all infected material. It is suggested that "up to 25% of P3 can be removed without adversely affecting bone integrity". Systemic and regionally perfused antibiotics are administered, and following surgery the foot must be checked and covered with a sterile bandage daily.
See also An In-Depth Look at Puncture Wounds to the Foot - W Rich Redding - AAEP 2010
Once osteomyelitis develops, treatment can be challenging, particularly outside of a clinic - prevention is much easier than cure.
On p 350 of Care and Rehabilitation of the Equine Foot, Pete Ramey talks about runaway necrosis of the corium, where horses have recurring abscessing with extreme pain, and mostly either lie down or stand in an exaggerated rocked back laminitis stance or vertical stance. Padding the feet doesn't usually ease the pain, but a palmar digital nerve block will. Venograms tend to show that the infection is due to "dead" areas in the corium, either at the sole due to chronic pressure (from uncorrected P3 rotation) or at the coronet following rapid or severe distal descent. He suggests that when these "dead" areas are seen in the corium, the situation may be hopeless and it may not be worth attempting rehabilitation.
Instead, every attempt should be made to prevent this happening: “at the first signs of laminitis, restore P3 to a more natural ground plane" (i.e. 3-5 degree palmar angle), "relieve pressure on the walls and pad the sole with foam rubber – vertical sinking and destructive pressure to the solar corium can be prevented”. Constant pressure on the solar corium and separational forces on the laminae and coronary papillae must be eliminated immediately.
Laminitis rehabilitation: If the corium is happy, there is hope - Dr Debra Taylor - Western Veterinary Conference 2013
See Maggot debridement therapy and Regional Limb Perfusion.
Subsolar Abscess and Coffin Bone Osteomyelitis - ACVS
What is that hole in the coffin bone? Diagnosis and Treatment of Septic Pedal Osteitis and Keratomas in the Horse - Ashleigh Olds-Sanchez 2019
Traumatic Foot Injuries in Horses: Surgical Management - Daniel Burba - Vetlearn Jan 2013
Osteomyelitis in Horse’s Feet - Butler Farrier School February 2013
Equine Foot Surgery: A Joint Venture With the Farrier - CM Honnas, D Sustaire - AAEP 2010
Werpy N
The use of magnetic resonance imaging for the diagnosis of osteomyelitis
Equine Veterinary Education Volume 26, Issue 1, pages 15–17, January 2014
Neil KM, Axon JE, Todhunter PG, Adams PL, Caron JP, Adkins AR
Septic osteitis of the distal phalanx in foals: 22 cases (1995-2002)
J Am Vet Med Assoc. 2007 Jun 1;230(11):1683-90
Cauvin, ERJ
The surgical treatment of septic pedal osteitis in the horse: a review of eight cases.
Dissertation November 1993 University of Glasgow
Some experiences of osteomyelitis
When a hoof abscess goes bad - slideshow of surgical debridement of coffin bone by Shirley McQuillan of Touchstone Farm
(Direct link to slideshow)
Horse was 3 legged lame for 3 days in spite of soaking and poulticing and eruption of abscess through the sole. X-rays showed large abscess and tip of P3 infected. A hospital plate shoe was glued on to stabilize the foot, all necrotic tissue removed from the bone, the wound flushed with Betadine and dressed, then the rest of the sole packed with putty for support and the (removable) bottom of the hospital plate screwed in place. A couple of days later medical maggots were put into the wound site ("When they go in they look like tiny grains of white rice. When they come out they are big and fat and creepy"). The horse was sound almost immediately. Treatment carried out by Rood & Riddle.
Other experiences described on the link above):
A mare's abscess wasn't improving with usual treatments even after the farrier dug into the abscess, horse could hardly walk. X-ray showed osteomyelitis in P3. Treated for 4 days with CleanTrax and LA200, wrapped foot in a slipper and treated hole with Xenodine.
Edge of P3 debrided by surgeons and a hospital plate fitted. Wound packed with small antibiotic beads (about the size of a pea), then packed with saline-soaked gauze. Once home the owner had to remove the hospital plate, remove the guaze, flush the wound with saline and repack it every day to keep the wound sterile. The horse was being ridden again in around 3 weeks and recovered beautifully.
Osteomyelitis/septic pedal osteitis describes infection of the coffin/pedal bone - purulent exudate (pus) will be present. What initially appears to be a "normal" foot abscess may progress to osteomyelitis if the infection does not form a contained abscess, or if an abscess does not resolve and spreads into the coffin/pedal bone. Osteomyelitis of the pedal/coffin bone can follow laminitis with severe rotation/sinking, often after penetration of the sole or long-term abscessing that extends into the bone. Osteomyelitis can also follow penetrating wounds to the foot, or fractures of the pedal/coffin bone.
Osteomyelitis should always be treated as a life threatening emergency. Once infection has invaded the coffin/pedal bone, intense treatment will usually be required, usually in a clinic, involving surgical debridement of the bone and antibiotics. Treating osteomyelitis conservatively greatly decreases the prognosis and increases the risk of supporting limb laminitis in the other feet.
Diagnosis:
If a foot abscess and associated lameness do not respond as quickly as expected, or if discharge continues for longer than expected, osteomyelitis should be considered.
An abscess drainage hole may lead to P3 on clinical examination of the foot.
X-rays, particularly 60' DP views, should be taken, and venograms may help assess blood flow to the infected area.
Treatment is likely to consist of surgery and antibiotics:
Surgery is likely to be required to remove the infected part of the coffin/pedal bone. Surgical debridement of the bone is usually carried out in a clinic, with the horse standing but sedated and local anaesthesia. The ACVS recommends approaching the area of infected bone through the hoof wall (hoof wall resection) rather than through the sole. Following surgery the foot must be kept sterile and then clean.
Antibiotic treatment may be systemic and via regional limb perfusion (RLP), and should be targeted at bacteria identified from bacterial culture of the infected tissue. RLP involves applying a tourniquet to the affected limb and introducing high dose antibiotics below the tourniquet, leading to high levels of antibiotics in the affected tissues. Frequent RLP treatments may be required.
Medical maggot therapy can also be used to debride the necrotic tissue.
Anti-inflammatory and analgesic treatment is likely to be necessary.
See: Subsolar Abscess and Coffin Bone Osteomyelitis - ACVS
Equine Podiatry edited by Andrea Floyd and Richard Mansmann in a chapter written by W Rich Redding p 276 suggests that the infected bone and soft tissue should be debrided and the infection drained, gaining access via the draining tract if possible and being sure to remove all infected material. It is suggested that "up to 25% of P3 can be removed without adversely affecting bone integrity". Systemic and regionally perfused antibiotics are administered, and following surgery the foot must be checked and covered with a sterile bandage daily.
See also An In-Depth Look at Puncture Wounds to the Foot - W Rich Redding - AAEP 2010
Once osteomyelitis develops, treatment can be challenging, particularly outside of a clinic - prevention is much easier than cure.
On p 350 of Care and Rehabilitation of the Equine Foot, Pete Ramey talks about runaway necrosis of the corium, where horses have recurring abscessing with extreme pain, and mostly either lie down or stand in an exaggerated rocked back laminitis stance or vertical stance. Padding the feet doesn't usually ease the pain, but a palmar digital nerve block will. Venograms tend to show that the infection is due to "dead" areas in the corium, either at the sole due to chronic pressure (from uncorrected P3 rotation) or at the coronet following rapid or severe distal descent. He suggests that when these "dead" areas are seen in the corium, the situation may be hopeless and it may not be worth attempting rehabilitation.
Instead, every attempt should be made to prevent this happening: “at the first signs of laminitis, restore P3 to a more natural ground plane" (i.e. 3-5 degree palmar angle), "relieve pressure on the walls and pad the sole with foam rubber – vertical sinking and destructive pressure to the solar corium can be prevented”. Constant pressure on the solar corium and separational forces on the laminae and coronary papillae must be eliminated immediately.
Laminitis rehabilitation: If the corium is happy, there is hope - Dr Debra Taylor - Western Veterinary Conference 2013
See Maggot debridement therapy and Regional Limb Perfusion.
Subsolar Abscess and Coffin Bone Osteomyelitis - ACVS
What is that hole in the coffin bone? Diagnosis and Treatment of Septic Pedal Osteitis and Keratomas in the Horse - Ashleigh Olds-Sanchez 2019
Traumatic Foot Injuries in Horses: Surgical Management - Daniel Burba - Vetlearn Jan 2013
Osteomyelitis in Horse’s Feet - Butler Farrier School February 2013
Equine Foot Surgery: A Joint Venture With the Farrier - CM Honnas, D Sustaire - AAEP 2010
Werpy N
The use of magnetic resonance imaging for the diagnosis of osteomyelitis
Equine Veterinary Education Volume 26, Issue 1, pages 15–17, January 2014
Neil KM, Axon JE, Todhunter PG, Adams PL, Caron JP, Adkins AR
Septic osteitis of the distal phalanx in foals: 22 cases (1995-2002)
J Am Vet Med Assoc. 2007 Jun 1;230(11):1683-90
Cauvin, ERJ
The surgical treatment of septic pedal osteitis in the horse: a review of eight cases.
Dissertation November 1993 University of Glasgow
Some experiences of osteomyelitis
When a hoof abscess goes bad - slideshow of surgical debridement of coffin bone by Shirley McQuillan of Touchstone Farm
(Direct link to slideshow)
Horse was 3 legged lame for 3 days in spite of soaking and poulticing and eruption of abscess through the sole. X-rays showed large abscess and tip of P3 infected. A hospital plate shoe was glued on to stabilize the foot, all necrotic tissue removed from the bone, the wound flushed with Betadine and dressed, then the rest of the sole packed with putty for support and the (removable) bottom of the hospital plate screwed in place. A couple of days later medical maggots were put into the wound site ("When they go in they look like tiny grains of white rice. When they come out they are big and fat and creepy"). The horse was sound almost immediately. Treatment carried out by Rood & Riddle.
Other experiences described on the link above):
A mare's abscess wasn't improving with usual treatments even after the farrier dug into the abscess, horse could hardly walk. X-ray showed osteomyelitis in P3. Treated for 4 days with CleanTrax and LA200, wrapped foot in a slipper and treated hole with Xenodine.
Edge of P3 debrided by surgeons and a hospital plate fitted. Wound packed with small antibiotic beads (about the size of a pea), then packed with saline-soaked gauze. Once home the owner had to remove the hospital plate, remove the guaze, flush the wound with saline and repack it every day to keep the wound sterile. The horse was being ridden again in around 3 weeks and recovered beautifully.
Overweight - see Obesity
Oxidative stress
Banse HE, Frank N, Kwong GP, McFarlane D
Relationship of oxidative stress in skeletal muscle with obesity and obesity-associated hyperinsulinemia in horses
Can J Vet Res. 2015 Oct;79(4):329-38 (PubMed)
"In conclusion, although oxidative stress in skeletal muscle appears to occur with equine obesity, oxidative damage does not appear to be associated with obesity and is therefore unlikely to be central to obesity-associated hyperinsulinemia."
Vet J. 2008 Aug;177(2):178-91. Epub 2007 Sep 25 (PubMed)
The oxidant/antioxidant equilibrium in horses
Kirschvink N, de Moffarts B, Lekeux P
"Oxidants are essentially generated by metabolic enzymes, inflammatory cells and mitochondrial electron leakage; they are indispensable for the cellular redox regulation and may, under certain conditions, have a pro-inflammatory stimulatory role. Endogenous and exogenous antioxidants counterbalance the oxidative processes and so maintain the oxidant/antioxidant equilibrium. Excessive oxidant generation or antioxidant insufficiency can lead to oxidative stress."
Vet Clin North Am Equine Pract. 2007 May;23(1):135-57 (PubMed)
Oxidative stress
Soffler C
"Oxidative stress refers to the cellular injury and pathologic change that occurs when there is an imbalance favoring oxidants over antioxidants within a living organism."
Am J Vet Res. 2005 Dec;66(12):2065-72 PubMed
Systemic and pituitary pars intermedia antioxidant capacity associated with pars intermedia oxidative stress and dysfunction in horses
McFarlane D, Cribb AE
"CONCLUSIONS AND CLINICAL RELEVANCE: There was no evidence of systemic accumulation of oxidative stress markers or deficiencies in antioxidant capacity in horses with PPID, suggesting that these are unlikely to be major predisposing factors in the development of PPID. Manganese superoxide dismutase activity in the pars intermedia decreased significantly with increasing age. Role of an age-associated decrease in antioxidant capacity for the pars intermedia in the development of PPID in horses warrants further investigation."
Keen JA, McLaren M, Chandler KJ, McGorum BC
Biochemical indices of vascular function, glucose metabolism and oxidative stress in horses with equine Cushing's disease
Equine Vet J. 2004 Apr;36(3):226-9 (PubMed)
"The observed abnormalities in glucose metabolism and oxidative stress could potentially contribute to development of laminitis in horses with ECD, by similar mechanisms to those that cause microvascular dysfunction in human diabetics."
Oxidative stress in chronic laminitis - Equine Science Update