H
Hair
Hay
Hay soaking
Haylage
Heparin
Homeopathy
Hoof - see Feet A-Z
Hoof testers
Hoof/hoof wall surface temperature
Hops
Hyperhidrosis - excessive sweating
Hyperlipaemia
Hypertrichosis/hirsutism and hair coat changes
Hypothalamus/Hypothalamic-Pituitary Gland Axis
Hay
Hay soaking
Haylage
Heparin
Homeopathy
Hoof - see Feet A-Z
Hoof testers
Hoof/hoof wall surface temperature
Hops
Hyperhidrosis - excessive sweating
Hyperlipaemia
Hypertrichosis/hirsutism and hair coat changes
Hypothalamus/Hypothalamic-Pituitary Gland Axis
Hair
Haircoat changes are a sign of PPID. See Hypertrichosis/Hirsutism.
Innerå M, Petersen AD, Desjardins DR, Steficek BA, Rosser EJ Jr, Schott HC 2nd
Comparison of hair follicle histology between horses with pituitary pars intermedia dysfunction and excessive hair growth and normal aged horses
Vet Dermatol. 2013 Feb;24(1):212-7.e46-7
"These findings document that excessive hair growth (hypertrichosis) in PPID-affected horses is due to persistence of hair follicles in A (anagen). Furthermore, treatment with pergolide improved shedding and reduced the percentage of A follicles in PPID-affected horses."
Haircoat changes are a sign of PPID. See Hypertrichosis/Hirsutism.
Innerå M, Petersen AD, Desjardins DR, Steficek BA, Rosser EJ Jr, Schott HC 2nd
Comparison of hair follicle histology between horses with pituitary pars intermedia dysfunction and excessive hair growth and normal aged horses
Vet Dermatol. 2013 Feb;24(1):212-7.e46-7
"These findings document that excessive hair growth (hypertrichosis) in PPID-affected horses is due to persistence of hair follicles in A (anagen). Furthermore, treatment with pergolide improved shedding and reduced the percentage of A follicles in PPID-affected horses."
Hay
For weight loss and to reduce high glucose and insulin peaks, a diet based on hay/forage with a low sugar (ESC) and starch content is recommended for horses with IR/EMS. The Laminitis Site, and Dr Eleanor Kellon and the ECIR group, suggest that the total sugar and starch in the diet should not exceed 10% (on a dry matter basis). Fructans (the difference between ESC and WSC) do not cause insulin to increase and are currently (2018) considered unlikely to contribute to endocrinopathic laminitis. See Diet.
(Note that although the ACVIM consensus statement on EMS from 2010 suggests: "It is therefore recommended that NSC be calculated by adding starch and WSC percentages together, and this value should ideally fall below 10% of dry matter when feeding horses or ponies with EMS", because fructans do not cause insulin to rise, and because ESC and starch are digested in the small intestine, but fructans are fermented in the hind gut, NSC and WSC are not appropriate terms to describe horse food/diets. Instead ESC and starch (which can be lumped together as hydrolyzable carbohydrates), and fructans, should be used when describing horse food/diets.)
Harris PA, Ellis AD, Fradinho MJ, Jansson A, Julliand V, Luthersson N, Santos AS, Vervuert I
Review: Feeding conserved forage to horses: recent advances and recommendations
Animal. 2017 Jun;11(6):958-967. doi: 10.1017/S1751731116002469. Epub 2016 Nov 24 (Full paper on ResearchGate)
When can new hay be analysed and fed?
It depends on the moisture content of the hay at baling. Horse hay should be baled when it has between 12 and 15% moisture - hay with 15% moisture or less should not heat up, "sweat", become mouldy or change significantly in quality from the time it is baled, and should be fine to be fed to horses (or analysed) as soon as it is baled, as long as it is introduced gradually (as you would any other new feed). Hay baled with more than 20% moisture may "sweat" and lose nutrients for the first month after baling, but will generally be unsuitable for horses. See
Hay vs Haylage - Tracey Hammond October 2019 Dengie
Is old hay better for horses with laminitis by Kathryn Watts - www.safergrass.org,
Fresh-Baled Hay for Horses - KER June 2017
Hay baled with a moisture content of <12% can be fed straight after baling. "Wet" hay goes through a form of fermentation/curing and shouldn't be fed during this phase, probably up to 4 weeks after baling - however, hay that is too wet at baling shouldn't be fed to horses, full stop. As with all new feedstuffs, acclimate horses to new hay gradually.
Is old hay better for laminitics?
No - if correctly made with a water content less than 20%, there is unlikely to be any significant loss of NSC during storage. Old hay is however likely to have lower levels of the fat soluble vitamins A, D and E, and horses on a hay only diet (no grass) will usually need to have vitamin E supplemented. See Is old hay better for horses with laminitis by Katy Watts - www.safergrass.org
How much hay do horses eat and what hay do they like to eat?
Journal of Equine Veterinary Science published online 01 April 2012
Voluntary Intake of Four Hay Types by Horses
Rodiek AV, Jones BE
Does Sugar Concentration Determine Hay Preference by Horses? by Katy Watts - www.safergrass.org
How should hay be fed?
Unsurprisingly, this research found that horses take longer to eat hay in smaller holed haynets - using a hay net with 3.2 cm holes meant horses took on average 6.5 hours to eat their ration, compared to 3.1 hours for presumably the same size ration when fed on the ground and 3.4 hours when using a large holed haynet:
Glunk EC, Hathaway MR, Weber WJ, Sheaffer CC, Martinson KL
The effect of hay net design on rate of forage consumption when feeding adult horses
Journal of Equine Veterinary Science published online 19 May 2014
See also Haynet Design and Forage Consumption Rates Studied - Casie Bazay - www.thehorse.com - Aug 2014
See also Management strategies for EMS/Insulin Resistance.
Insulin and glucose concentrations following hay feeding:
Carslake HB, Argo C McG, Pinchbeck GL, Dugdale AHA, McGowan CM
Insulinaemic and glycaemic responses to three forages in ponies
The Veterinary Journal Volume 235, May 2018, Pages 83-89
Hay analysis
The only way to know the nutritional (including sugar/WSC/starch) content of hay is to have it analysed - you cannot tell the nutritional content by the colour of the hay, and old hay doesn't necessarily have less sugar than new hay.
TLS recommends having ESC analysed, rather than "sugar" or WSC. Companies that do this are ForagePlus in the UK (who send samples to Equi-Analytical), and Equi-Analytical in the USA.
Hay analysis is often divided into 2 sections:
a nutritional analysis which includes some or all of sugar/ESC, WSC, starch, crude protein, fibre or NDF and ADF, DE (energy) and moisture/dry matter content; and
a mineral analysis.
Wet chemistry actually analyses the sample and is the most accurate analysis. NIR matches a light spectrum reflection profile to a wet chemistry calibration, and may not be as accurate as wet chemistry (NIR can never be more accurate than wet chemistry). Minerals can only be analysed by wet chemistry.
Forage analysis companies
UK:
ForagePlus Analysis
Offers nutritional analysis by Equi-Analytical in the USA, either by NIR or wet chemistry, and mineral analysis carried out in the UK.
More expensive than sending samples directly to Equi-Analytical yourself, but less hassle as they deal with USA import regulations for you.
Dengie Forage Analysis
Dodson & Horrell Forage Analysis (D&H were using NIR analysis as at Sept 2012. As at 2020 we could not find details of their forage analysis)
Simple System Ltd Forage Analysis
Sciantec Forage
Sciantec offer analysis of single nutrients by wet chemistry, various mineral profiles, and hay/haylage testing by NIR.
Biosimetrics
USA:
Equi-Analytical
#603 Trainer is the analysis recommended by the ECIR group and TLS.
Canada:
A&L Canada Laboratories Inc
Methods of and research relating to forage analysis
Harris PA, Nelson S, Carslake HB, Argo Caroline McG, Wolf R, Fabri B, Brolsma KM, van Oostrum MJ, Ellis AD
Comparison of NIRS and Wet Chemistry Methods for the Nutritional Analysis of Haylages for Horses
Journal of Equine Veterinary Science published online 4 September 2018
Interpreting a hay analysis
For a horse with insulin dysregulation, the important figures on a hay analysis are ESC (simple sugars) and starch. A good hay analysis will report ESC, WSC and starch. The ECIR group recommends that combined ESC and starch should be below 10%. WSC = ESC plus fructans - there is currently little evidence that naturally eaten fructans increase insulin levels or contribute to the risk of laminitis - see Do fructans cause laminitis?
Common Terms used in Animal Feeding and Nutrition - University of Georgia UGA Extension - March 2017
Equine Hay Analysis - Martinson & Peterson, University of Minnesota
Equi-Analytical - Glossary of Nutrient Terms
How well do you know your hay? Sally Flis, Equi-Analytical Winter 2015 newsletter
Equi-Analytical have common feed profiles from the many samples that they analyse on their website. Below are average and standard range figures for grass hay samples from 2000 to 2014. Note that these samples will include C4 as well as C3 hay, and therefore may not be particularly representative of northern European/UK hay, which will be mostly C3. See Equi-Analytical Common Feed Profiles.
Commercial analysis of fructans may not be accurate:
J Sci Food Agric. 2012 Feb 1. doi: 10.1002/jsfa.5555. [Epub ahead of print] (PubMed)
Comparison of a colorimetric and a high-performance liquid chromatography method for the determination of fructan in pasture grasses for horses.
Longland AC, Dhanoa MS, Harris PA.
"RESULTS: Pasture grasses (Phleum pretense, Festuca rubra, Dactylis glomerata, Lolium perenne) managed for grazing (sampled from April to November) and a further set managed for conservation (sampled in July) were analysed for fructan content by HPLC and the colorimetric technique. HPLC values ranged from 83 to 299 g fructan kg(-1) DM (mean 154); corresponding colorimetric values were 5-238 g fructan kg(-1) DM (mean 82). Discrepancies in values between the two methods varied with time of sampling and plant species. Comparison of selected samples before and after incubation with the fructan hydrolases used in the colorimetric method revealed incomplete fructan hydrolysis from the pasture grasses, resulting in underestimates of their fructan content."
Can typical values for minerals in hay be used?
Hays analysed from the same area tend to have broadly similar profiles, e.g. high iron, low zinc and copper (although this is typical of most hays!), but actual mineral contents can vary considerably between fields or between years from the same field, so you cannot use your neighbour's or last year's hay analysis to accurately mineral balance your hay.
M. J. S. Moore-Colyer (1996).
Effects of soaking hay fodder for horses on dust and mineral content.
Animal Science, 63 , pp 337-342 doi:10.1017/S1357729800014892
4 bales of mature multi-species meadow hay were analysed. Sodium and calcium levels were similar in all 4 bales, but significant differences were found in levels of nitrogen (protein), phosphorus, potassium and magnesium between the 4 bales.
Hay/haylage suppliers
Hay and haylage suppliers that have their forage analysed by Equi-Analytical (or via a UK agent e.g. ForagePlus) and provide customers with figures for ESC and starch (which combined should be less than 10% on a dry matter basis for a horse with insulin dysregulation, EMS and/or endocrinopathic laminitis) and DE include:
Feet First Hay near Swindon, Wiltshire (UK)
Devon Haylage near Ottery st Mary, Devon (UK)
J Sci Food Agric. 2012 Feb 1. doi: 10.1002/jsfa.5555. [Epub ahead of print] (PubMed)
Comparison of a colorimetric and a high-performance liquid chromatography method for the determination of fructan in pasture grasses for horses.
Longland AC, Dhanoa MS, Harris PA.
"RESULTS: Pasture grasses (Phleum pretense, Festuca rubra, Dactylis glomerata, Lolium perenne) managed for grazing (sampled from April to November) and a further set managed for conservation (sampled in July) were analysed for fructan content by HPLC and the colorimetric technique. HPLC values ranged from 83 to 299 g fructan kg(-1) DM (mean 154); corresponding colorimetric values were 5-238 g fructan kg(-1) DM (mean 82). Discrepancies in values between the two methods varied with time of sampling and plant species. Comparison of selected samples before and after incubation with the fructan hydrolases used in the colorimetric method revealed incomplete fructan hydrolysis from the pasture grasses, resulting in underestimates of their fructan content."
Can typical values for minerals in hay be used?
Hays analysed from the same area tend to have broadly similar profiles, e.g. high iron, low zinc and copper (although this is typical of most hays!), but actual mineral contents can vary considerably between fields or between years from the same field, so you cannot use your neighbour's or last year's hay analysis to accurately mineral balance your hay.
M. J. S. Moore-Colyer (1996).
Effects of soaking hay fodder for horses on dust and mineral content.
Animal Science, 63 , pp 337-342 doi:10.1017/S1357729800014892
4 bales of mature multi-species meadow hay were analysed. Sodium and calcium levels were similar in all 4 bales, but significant differences were found in levels of nitrogen (protein), phosphorus, potassium and magnesium between the 4 bales.
Hay/haylage suppliers
Hay and haylage suppliers that have their forage analysed by Equi-Analytical (or via a UK agent e.g. ForagePlus) and provide customers with figures for ESC and starch (which combined should be less than 10% on a dry matter basis for a horse with insulin dysregulation, EMS and/or endocrinopathic laminitis) and DE include:
Feet First Hay near Swindon, Wiltshire (UK)
Devon Haylage near Ottery st Mary, Devon (UK)
Hay soaking
Minerals that are present in hay in a readily available ionic form will be leached out by soaking.
Sugars (glucose, fructose and sucrose) are more readily reduced by soaking than fructans (Longland et al. 2011).
Soaking your horse's hay - University of Minnesota 2021
Feed soaked hay straight after soaking to avoid mould growth.
The authors do not recommend soaking hay for > 1 hour as this could reduce palatability and nutrients.
Soaking reduced phosphorus and magnesium in all hays.
Soaking reduces dry matter, with increased DM loss the longer the soaking time. Ensure enough hay is soaked so that after soaking and DM loss, at least 1.5% of your horse's ideal bodyweight is actually fed (on a dry matter basis).
The figures in the graph show NSC, being WSC plus starch. ESC and starch (the sugars that increase insulin) are not given but cannot exceed NSC and will usually be (sometimes significantly) lower than NSC.
Minerals that are present in hay in a readily available ionic form will be leached out by soaking.
Sugars (glucose, fructose and sucrose) are more readily reduced by soaking than fructans (Longland et al. 2011).
Soaking your horse's hay - University of Minnesota 2021
Feed soaked hay straight after soaking to avoid mould growth.
The authors do not recommend soaking hay for > 1 hour as this could reduce palatability and nutrients.
Soaking reduced phosphorus and magnesium in all hays.
Soaking reduces dry matter, with increased DM loss the longer the soaking time. Ensure enough hay is soaked so that after soaking and DM loss, at least 1.5% of your horse's ideal bodyweight is actually fed (on a dry matter basis).
The figures in the graph show NSC, being WSC plus starch. ESC and starch (the sugars that increase insulin) are not given but cannot exceed NSC and will usually be (sometimes significantly) lower than NSC.
Glatter M, Bochnia M, Wensch-Dorendorf M, Greef JM, Zeyner A.
Feed Intake Parameters of Horses Fed Soaked or Steamed Hay and Hygienic Quality of Hay Stored following Treatment.
Animals (Basel). 2021 Sep 18;11(9):2729. doi: 10.3390/ani11092729. Open Access.
Moore-Colyer M, Longland A, Harris P, Zeef L, Crosthwaite S.
Mapping the bacterial ecology on the phyllosphere of dry and post soaked grass hay for horses.
PLoS One. 2020 Jan 27;15(1):e0227151. doi: 10.1371/journal.pone.0227151. PMID: 31986161; PMCID: PMC6984722.
Bochnia M, Pietscha C, Wensch-Dorendorf M, Greef M, Zeyner A
Effect of hay soaking duration on metabolizable energy, total and prececal digestible crude protein and amino acids, non-starch carbohydrates, macronutrients and trace elements
Journal of Equine Veterinary Science Published online March 2021
Keywords: hay, nutrient composition, prececal digestible crude protein, soaking, water soluble carbohydrates
Owens TG, Barnes M, Gargano VM, Julien L, Mansilla WD, Devries TJ, Mcbride BW, Merkies K, Shoveller AK.
Nutrient content changes from steaming or soaking timothy-alfalfa hay: effects on feed preferences and acute glycemic response in Standardbred racehorses.
J Anim Sci. 2019 Oct 3;97(10):4199-4207. doi: 10.1093/jas/skz252.
[Note that WSC (and ESC) were analysed by NIR, which as at 2021 is considered (by Pat Harris) to be unreliable for testing WSC (with ESC not analysed and compared). Source: Harris et al. 2018 Comparison of NIRS and Wet Chemistry Methods for the Nutritional Analysis of Haylages for Horses JEVS published online 4 September 2018, and mentioned in Mars webinar 2021.]
Wassel, Brooklyne M
Solubilization of nonstructural carbohydrates as a function of soaking interval and water temperature in southern forages commonly fed to equids
MSc thesis Auburn University May 2017
Müller CE, Nostell K, Bröjer J
Methods for reduction of water soluble carbohydrate content in grass forages for horses
Livestock Science Volume 186, April 2016, Pages 46-52
Müller CE, Nostell K, Bröjer J
Microbial Counts in Forages for Horses—Effect of Storage Time and of Water Soaking Before Feeding
JEVS July 2015 Volume 35, Issue 7, Pages 622–627
Hay, haylage and silage was analyzed for yeast, mould and bacteria before and after soaking in water for 24 hours.
Soaking increased counts of yeasts and lactic acid bacteria (LAB).
Enterobacteria counts increased after soaking silage and haylage, but not hay.
Soaking decreased mould counts in hay, but soaked hay had higher mould counts than unsoaked silage and haylage.
"Soaking forage for 24 hours may therefore reduce the hygienic quality of forage."
Collins J
The effect of hay type and soaking on glycemic response in horses
MSc thesis Middle Tennessee State University May 2015
Soak Away Your Hay's Hidden Dangers - Stacey Oke, March 2015, www.thehorse.com
Moore-Colyer MJS, Lumbis K, Longland A, Harris P
The Effect of Five Different Wetting Treatments on the Nutrient Content and Microbial Concentration in Hay for Horses
PLOS One November 26, 2014
Mack SJ, Dugdale AH, Argo CM, Morgan RA, McGowan CM
Impact of water-soaking on the nutrient composition of UK hays
Vet Rec. 2014 May 3;174(18):452. doi: 10.1136/vr.102074. Epub 2014 Mar 27
Journal of Equine Veterinary Science published online 16 April 2012
The Effect of Soaking on Protein and Mineral Loss in Orchardgrass and Alfalfa Hay
Martinson KL, Hathaway M, Jung H, Sheaffer C
Soaking different hays caused protein to remain the same, increase and decrease.
Calcium, phosphorus, potassium and magnesium were reduced with longer soaking times. Phosphorus supplementation would have been necessary when feeding hay soaked for 12 hours.
See also: Hay Soaking: All Washed Up or a Good Management Option? University of Minnesota Extension
Journal of Equine Veterinary Science published online 23 December 2011
The Effect of Soaking on Carbohydrate Removal and Dry Matter Loss in Orchardgrass and Alfalfa Hays
Martinson K, Jung H, Hathaway M, Sheaffer C
Vet Rec. 2011 Jun 11;168(23):618 (PubMed)
Effects of soaking on the water-soluble carbohydrate and crude protein content of hay
Longland AC, Barfoot C, Harris PA
"The aim of this study was to determine the amounts of water-soluble carbohydrate (WSC), WSC constituents and protein leached from a range of U.K. hays soaked according to common practice. Initial hay WSC content ranged from 123 to 230 g/kg dry matter (DM). Soaking the hays for up to 16 hours in water at a mean temperature of 8°C resulted in a mean loss of 27 per cent (range 6 to 54 per cent) of hay WSC. The mean percentage losses of WSC constituents were 24 per cent (range 14 to 31) for fructan, 41 per cent (range 21 to 70) for fructose, 45 per cent (range 28 to 100) for sucrose and 56 per cent (range 29 to 100) for glucose. The mean crude protein content of the initial hays was 58.7 g/kg DM (range 30 to 86 g/kg DM) and this value was not affected significantly by soaking. Despite a mean WSC loss of 27 per cent, the WSC contents of seven of the hays remained above the suggested upper limit for laminitic animals of 100 g/kg DM."
See also: Soaking Hay in Water Reduces Water Soluble Carbohydrates - www.anderson-hay.com 2012
(But note that fructans do not increase insulin and there is no evidence that naturally ingested fructans cause or exacerbate laminitis).
Feed Intake Parameters of Horses Fed Soaked or Steamed Hay and Hygienic Quality of Hay Stored following Treatment.
Animals (Basel). 2021 Sep 18;11(9):2729. doi: 10.3390/ani11092729. Open Access.
Moore-Colyer M, Longland A, Harris P, Zeef L, Crosthwaite S.
Mapping the bacterial ecology on the phyllosphere of dry and post soaked grass hay for horses.
PLoS One. 2020 Jan 27;15(1):e0227151. doi: 10.1371/journal.pone.0227151. PMID: 31986161; PMCID: PMC6984722.
Bochnia M, Pietscha C, Wensch-Dorendorf M, Greef M, Zeyner A
Effect of hay soaking duration on metabolizable energy, total and prececal digestible crude protein and amino acids, non-starch carbohydrates, macronutrients and trace elements
Journal of Equine Veterinary Science Published online March 2021
Keywords: hay, nutrient composition, prececal digestible crude protein, soaking, water soluble carbohydrates
Owens TG, Barnes M, Gargano VM, Julien L, Mansilla WD, Devries TJ, Mcbride BW, Merkies K, Shoveller AK.
Nutrient content changes from steaming or soaking timothy-alfalfa hay: effects on feed preferences and acute glycemic response in Standardbred racehorses.
J Anim Sci. 2019 Oct 3;97(10):4199-4207. doi: 10.1093/jas/skz252.
[Note that WSC (and ESC) were analysed by NIR, which as at 2021 is considered (by Pat Harris) to be unreliable for testing WSC (with ESC not analysed and compared). Source: Harris et al. 2018 Comparison of NIRS and Wet Chemistry Methods for the Nutritional Analysis of Haylages for Horses JEVS published online 4 September 2018, and mentioned in Mars webinar 2021.]
Wassel, Brooklyne M
Solubilization of nonstructural carbohydrates as a function of soaking interval and water temperature in southern forages commonly fed to equids
MSc thesis Auburn University May 2017
Müller CE, Nostell K, Bröjer J
Methods for reduction of water soluble carbohydrate content in grass forages for horses
Livestock Science Volume 186, April 2016, Pages 46-52
Müller CE, Nostell K, Bröjer J
Microbial Counts in Forages for Horses—Effect of Storage Time and of Water Soaking Before Feeding
JEVS July 2015 Volume 35, Issue 7, Pages 622–627
Hay, haylage and silage was analyzed for yeast, mould and bacteria before and after soaking in water for 24 hours.
Soaking increased counts of yeasts and lactic acid bacteria (LAB).
Enterobacteria counts increased after soaking silage and haylage, but not hay.
Soaking decreased mould counts in hay, but soaked hay had higher mould counts than unsoaked silage and haylage.
"Soaking forage for 24 hours may therefore reduce the hygienic quality of forage."
Collins J
The effect of hay type and soaking on glycemic response in horses
MSc thesis Middle Tennessee State University May 2015
Soak Away Your Hay's Hidden Dangers - Stacey Oke, March 2015, www.thehorse.com
Moore-Colyer MJS, Lumbis K, Longland A, Harris P
The Effect of Five Different Wetting Treatments on the Nutrient Content and Microbial Concentration in Hay for Horses
PLOS One November 26, 2014
Mack SJ, Dugdale AH, Argo CM, Morgan RA, McGowan CM
Impact of water-soaking on the nutrient composition of UK hays
Vet Rec. 2014 May 3;174(18):452. doi: 10.1136/vr.102074. Epub 2014 Mar 27
Journal of Equine Veterinary Science published online 16 April 2012
The Effect of Soaking on Protein and Mineral Loss in Orchardgrass and Alfalfa Hay
Martinson KL, Hathaway M, Jung H, Sheaffer C
Soaking different hays caused protein to remain the same, increase and decrease.
Calcium, phosphorus, potassium and magnesium were reduced with longer soaking times. Phosphorus supplementation would have been necessary when feeding hay soaked for 12 hours.
See also: Hay Soaking: All Washed Up or a Good Management Option? University of Minnesota Extension
Journal of Equine Veterinary Science published online 23 December 2011
The Effect of Soaking on Carbohydrate Removal and Dry Matter Loss in Orchardgrass and Alfalfa Hays
Martinson K, Jung H, Hathaway M, Sheaffer C
Vet Rec. 2011 Jun 11;168(23):618 (PubMed)
Effects of soaking on the water-soluble carbohydrate and crude protein content of hay
Longland AC, Barfoot C, Harris PA
"The aim of this study was to determine the amounts of water-soluble carbohydrate (WSC), WSC constituents and protein leached from a range of U.K. hays soaked according to common practice. Initial hay WSC content ranged from 123 to 230 g/kg dry matter (DM). Soaking the hays for up to 16 hours in water at a mean temperature of 8°C resulted in a mean loss of 27 per cent (range 6 to 54 per cent) of hay WSC. The mean percentage losses of WSC constituents were 24 per cent (range 14 to 31) for fructan, 41 per cent (range 21 to 70) for fructose, 45 per cent (range 28 to 100) for sucrose and 56 per cent (range 29 to 100) for glucose. The mean crude protein content of the initial hays was 58.7 g/kg DM (range 30 to 86 g/kg DM) and this value was not affected significantly by soaking. Despite a mean WSC loss of 27 per cent, the WSC contents of seven of the hays remained above the suggested upper limit for laminitic animals of 100 g/kg DM."
See also: Soaking Hay in Water Reduces Water Soluble Carbohydrates - www.anderson-hay.com 2012
(But note that fructans do not increase insulin and there is no evidence that naturally ingested fructans cause or exacerbate laminitis).
|
Longland AC, Barfoot C, Harris PA
Effect of period, water temperature and agitation on loss of water-soluble carbohydrates and protein from grass hay: implications for equine feeding management Vet Rec. 2014 Jan 18;174(3):68. doi: 10.1136/vr.101820. Epub 2013 Dec 13 A.C. Longland, C. Barfoot and P.A. Harris The effect of water temperature on loss of water-soluble carbohydrates from hay soaked in water for up to 16 hours 5th European Workshop Equine Nutrition 2010 See Spillers website - The science behind Spillers Journal of Animal Science 88 (E-supplement 2): 202 (2010) Soaking Hay in Water to Reduce Soluble Carbohydrate Concentrations Prior to Horse Feeding Martinson K, Sheaffer C, Jung H The type of hay, length of time the hay is soaked and temperature of the water used all affected ESC, WSC and fructan losses. |
Research by Longland et al 2013 recorded a 28% loss of total simple sugars or ESC (glucose, fructose and sucrose) after 1 hour's soaking in 8'C water, which increased to a 53% loss (an additional 25% loss compared to 1 hour) after 16 hour's soaking. Using warmer water (16'C) increased total sugar losses to 48% after 1 hour and 74% after 16 hours (an additional 26% loss compared to 1 hour). As the hay samples started at less than 10% sugar and a 1 hour soak brought all samples to less than 6% sugar, there seems little benefit in soaking for more than 1 hour, particularly in hot weather when soaking may cause bacterial overgrowth/fermentation.
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Soaking hay to remove excess soluble carbohydrate and potassium - Kathryn Watts www.safergrass.org
M. Blackman and M. J. S. Moore-Colyer (1998).
Hay for horses: the effects of three different wetting treatments on dust and nutrient content.
Animal Science, 66 , pp 745-750 doi:10.1017/S1357729800009334
4 x 2.5 kg samples were taken from 5 bales of 6 month old hay (85% ryegrass and 12% meadow grasses) and either not treated, soaked for 10 minutes, soaked for 30 minutes or steamed for 80 minutes. Soaked hay (2.5 kg hay in individual haynets) was completely submerged in 45 litres of water then drained for 1 hour. All treatments reduced respirable particles.
Soaking hay for 10 minutes and 30 minutes significantly reduced levels of sodium, potassium, magnesium, phosphorus and copper (but not nitrogen, calcium, zinc, manganese and iron). There were significant differences in mineral levels (apart from phosphorus between the bales.
The authors suggested that horses with COPD (now called RAO or equine asthma) should be fed vacuum-packed dust-free forage, and that soaking or steaming might reduce the respirable challenge to healthy horses.
M. J. S. Moore-Colyer (1996).
Effects of soaking hay fodder for horses on dust and mineral content.
Animal Science, 63 , pp 337-342 doi:10.1017/S1357729800014892
2.5 kg sections of mature meadow hay were soaked in 54L water for 0 mins, 30 mins, 3 hours and 12 hours and sodium, potassium, phosphorus, magnesium, calcium and nitrogen (protein) was measured. WSC was 4.1% in the unsoaked hay and wasn't analysed after soaking.
Sodium: (content of dry hay was high at 0.63%, compared to NRC 2007 0.02%, Dengie typical range 0.05-0.15%) 42% was lost after 30 minutes soaking, 60% after 3 hours, 69% after 12 hours.
Potassium: (1.45% dry hay, NRC 2007 1.97%, Dengie 1.5-2.5%) 27% was lost after 30 minutes soaking, 57% after 3 hours, 63% after 12 hours.
Phosphorus: (0.28% dry hay, NRC 0.26%, Dengie 0.1-0.3%) 14% was lost after 30 minutes soaking, 35% after 3 hours, 39% after 12 hours.
Magnesium: (0.16% dry hay, NRC 0.18%, Dengie 0.1-0.2%) 0% was lost after 30 minutes soaking, 18% after 3 hours, 25% after 12 hours.
Calcium: (0.37% dry hay, NRC 0.47%, Dengie 0.25-0.65%) no losses.
Nitrogen: no losses.
WARR, E. M. and PETCH, J. L. (1993)
Effects of soaking hay on its nutritional quality.
Equine Veterinary Education, 5: 169–171. doi: 10.1111/j.2042-3292.1993.tb01031.x
Is there any danger feeding soaked hay?
Wet and warm conditions can lead to fermentation and bacterial growth. Always feed hay soon after soaking it and dispose of any uneaten hay out of horses' reach. According to With Horse Hay, Wetter Can Be Better - Eleanor Kellon VMD (was found at www.wheelyhay.com)
"when soaking in hot weather, you can get bacterial overgrowth very rapidly, so in those cases don't soak longer than two hours."
M. Blackman and M. J. S. Moore-Colyer (1998).
Hay for horses: the effects of three different wetting treatments on dust and nutrient content.
Animal Science, 66 , pp 745-750 doi:10.1017/S1357729800009334
4 x 2.5 kg samples were taken from 5 bales of 6 month old hay (85% ryegrass and 12% meadow grasses) and either not treated, soaked for 10 minutes, soaked for 30 minutes or steamed for 80 minutes. Soaked hay (2.5 kg hay in individual haynets) was completely submerged in 45 litres of water then drained for 1 hour. All treatments reduced respirable particles.
Soaking hay for 10 minutes and 30 minutes significantly reduced levels of sodium, potassium, magnesium, phosphorus and copper (but not nitrogen, calcium, zinc, manganese and iron). There were significant differences in mineral levels (apart from phosphorus between the bales.
The authors suggested that horses with COPD (now called RAO or equine asthma) should be fed vacuum-packed dust-free forage, and that soaking or steaming might reduce the respirable challenge to healthy horses.
M. J. S. Moore-Colyer (1996).
Effects of soaking hay fodder for horses on dust and mineral content.
Animal Science, 63 , pp 337-342 doi:10.1017/S1357729800014892
2.5 kg sections of mature meadow hay were soaked in 54L water for 0 mins, 30 mins, 3 hours and 12 hours and sodium, potassium, phosphorus, magnesium, calcium and nitrogen (protein) was measured. WSC was 4.1% in the unsoaked hay and wasn't analysed after soaking.
Sodium: (content of dry hay was high at 0.63%, compared to NRC 2007 0.02%, Dengie typical range 0.05-0.15%) 42% was lost after 30 minutes soaking, 60% after 3 hours, 69% after 12 hours.
Potassium: (1.45% dry hay, NRC 2007 1.97%, Dengie 1.5-2.5%) 27% was lost after 30 minutes soaking, 57% after 3 hours, 63% after 12 hours.
Phosphorus: (0.28% dry hay, NRC 0.26%, Dengie 0.1-0.3%) 14% was lost after 30 minutes soaking, 35% after 3 hours, 39% after 12 hours.
Magnesium: (0.16% dry hay, NRC 0.18%, Dengie 0.1-0.2%) 0% was lost after 30 minutes soaking, 18% after 3 hours, 25% after 12 hours.
Calcium: (0.37% dry hay, NRC 0.47%, Dengie 0.25-0.65%) no losses.
Nitrogen: no losses.
WARR, E. M. and PETCH, J. L. (1993)
Effects of soaking hay on its nutritional quality.
Equine Veterinary Education, 5: 169–171. doi: 10.1111/j.2042-3292.1993.tb01031.x
Is there any danger feeding soaked hay?
Wet and warm conditions can lead to fermentation and bacterial growth. Always feed hay soon after soaking it and dispose of any uneaten hay out of horses' reach. According to With Horse Hay, Wetter Can Be Better - Eleanor Kellon VMD (was found at www.wheelyhay.com)
"when soaking in hot weather, you can get bacterial overgrowth very rapidly, so in those cases don't soak longer than two hours."
Haylage
Is haylage suitable to feed to a laminitic pony?
The fermentation process in correctly made haylage will significantly reduce the WSC levels from those in the freshly cut grass. Marksway Horsehage gives figures representing typical samples of <3% sugar and 1-2% starch for all their haylage products (the ACVIM consensus statement on EMS recommends feeding <10% combined WSC (sugar) and starch (all figures DM)).
In her book The Truth About Feeding Your Horse (2007), nutritionist Clare MacLeod says "Haylage can be a safe feed for laminitis-prone horses and ponies, but a high dry matter, high-fibre, low-protein haylage with low residual sugars should be selected."
If you decide to try haylage, as with all new feeds, introduce it slowly over several days, and monitor your horse closely.
Hay or haylage for horses: a comparison
Johanna Besier, Brigitte Strickler, Ruedi von Niederhäusern and Ueli Wyss
Leng J, McNally S, Walton G, Swann J, Proudman C, Argo C, Emery S, La Ragione R, Eustace R.
Hay vs. haylage; forage type influences the equine urinary metabonome and faecal microbiota.
Equine Vet J. 2021 Apr 26. doi: 10.1111/evj.13456. Epub ahead of print. PMID: 33900659.
Can haylage be soaked before feeding?
Soaking haylage is not generally recommended as there is a risk of starting a secondary fermentation which could result in the proliferation of undesirable micro-organisms. The sugar and starch content in correctly made haylage is usually low enough that further reduction should not be necessary for most laminitic horses.
All About Hay and Haylage - Nic Barker, Rockley Farm blog Nov 2011
"Haylage need not be soaked because (a) high levels of water soluble sugars are not present and (b) once wet, it goes off and becomes unpalatable extremely quickly"
From Equine Applied and Clinical Nutrition - R Geor, P Harris, M Coenen 2013 p 378 - silage or haylage with a high moisture content can undergo a process of secondary fermentation within hours at high temperatures or within 2-5 days at low temperatures.
Botulism in adult horses is most commonly caused by horses eating poorly conserved forage (silage, haylage, hay or straw) - pH above 4.5 and/or high water content may encourage the growth of clostridium botulinum - see Equine Applied and Clinical Nutrition - R Geor, P Harris, M Coenen 2013 p 601.
Insulin and glucose concentrations following haylage feeding:
Lindåse S, Müller C, Nostell K, Bröjer J
Evaluation of glucose and insulin response to haylage diets with different content of nonstructural carbohydrates in 2 breeds of horses
Domest Anim Endocrinol. 2018 Jul;64:49-58. doi: 10.1016/j.domaniend.2018.03.006. Epub 2018 Apr 9
Carslake HB, Argo C McG, Pinchbeck GL, Dugdale AHA, McGowan CM
Insulinaemic and glycaemic responses to three forages in ponies
The Veterinary Journal Volume 235, May 2018, Pages 83-89
Hay/haylage suppliers
Hay and haylage suppliers that have their forage analysed by Equi-Analytical (or via a UK agent e.g. ForagePlus) and provide customers with figures for ESC and starch (which combined should be less than 10% on a dry matter basis for a horse with insulin dysregulation, EMS and/or endocrinopathic laminitis) and DE include:
Feet First Hay near Swindon, Wiltshire (UK)
Devon Haylage near Ottery st Mary, Devon (UK)
Research
Müller Cecilia E
Wrapped Forages for Horses
PhD thesis 2007 Swedish University of Agricultural Sciences
Heparin
Am J Vet Res. 2010 Dec;71(12):1462-7 (PubMed)
Effect of heparin administration on urine protein excretion during the developmental stage of experimentally induced laminitis in horses
Uberti B, Pressler BM, Alkabes SB, Chang CY, Moore GE, Lescun TB, Sojka JE
"OBJECTIVE: To investigate the effects of heparin administration on urine protein excretion during the developmental stages of experimentally induced laminitis in horses.
ANIMALS: 13 horses. Procedures-Horses received unfractionated heparin (80 U/kg, SC, q 8 h; n=7) or no treatment (control group; 6) beginning 3 days prior to induction of laminitis. All horses were given 3 oligofructose loading doses (1 g/kg each) at 24-hour intervals and a laminitis induction dose (10 g of oligofructose/kg) 24 hours following the final loading dose (designated as 0 hours) via nasogastric tube. Serum glucose and insulin concentrations were measured before administration of the first loading dose (baseline) and at 0 and 24 hours; urine protein-to-creatinine (UP:C) ratio was determined at 0 hours and every 4 hours thereafter. Lameness was evaluated every 6 hours, and horses were euthanized when Obel grade 2 lameness was observed.
RESULTS: Mean±SD time until euthanasia did not differ significantly between the heparin-treated (28.9±6.5 hours) and control (29.0±6.9 hours) horses. The UP:C ratio was significantly increased from baseline at 20 to 28 hours after induction of laminitis (ie, 4±4 hours before lameness was evident) in control horses but did not change significantly from baseline in heparin-treated horses. Serum glucose or insulin concentration did not change significantly from baseline in either group.
CONCLUSIONS AND CLINICAL RELEVANCE: Urine protein excretion increased during the developmental stages of carbohydrate-induced laminitis in horses; administration of heparin prevented that increase, but did not delay onset or decrease severity of lameness."
Journal of Veterinary Emergency and Critical Care 19(1) 2009, pp 113–119 (Full)
Evaluation of low-molecular-weight heparin for the prevention of equine laminitis after colic surgery
de la Rebiere de Pouyade G, Grulke S, Detilleux J, Salciccia A,Verwilghen DR, Caudron I, Gangl M, Serteyn DDA
Evidence-based treatment of the inflammatory component of laminitis
James K. Belknap, Rafael R. Faleiros, Rustin M. Moore
Homeopathy
M Elliott
Cushing's Disease: a new approach to therapy in equine and canine patients
British Homeopathic Journal (2001) 90,33-36
Please also read this critique of the above research on www.vetpath.co.uk - http://www.vetpath.co.uk/voodoo/elliott.html
Hoof testers
Viñuela-Fernandez I, Jones E, McKendrick IJ, Molony V
Quantitative assessment of increased sensitivity of chronic laminitic horses to hoof tester evoked pain
Equine Vet J. 2011 Jan;43(1):62-8. doi: 10.1111/j.2042-3306.2010.00137.x
Viñuela-Fernandez I, Jones E, McKendrick IJ, Molony V
Quantitative assessment of increased sensitivity of chronic laminitic horses to hoof tester evoked pain
Equine Vet J. 2011 Jan;43(1):62-8. doi: 10.1111/j.2042-3306.2010.00137.x
Hoof/hoof wall surface temperature
Is hoof/hoof wall surface temperature (HWST) a useful indication of laminitis?
Increased hoof/hoof wall surface temperature has been recorded in experimentally induced laminitis cases (sepsis-related and hyperinsulinaemia-associated). However, horses without laminitis can have fluctuations in hoof temperature throughout the day, with differences being measured between feet.
The measurement of HWST has been validated as a non-invasive index of blood flow in the foot by researchers, but under ambient temperature-controlled conditions.
Rosenmeier JG, Strathe AB, Andersen PH
Evaluation of coronary band temperatures in healthy horses
Am J Vet Res. 2012 May;73(5):719-23. doi: 10.2460/ajvr.73.5.719
4,320 coronary band temperatures (CBT) were obtained from 6 healthy, unshod, stalled horses fed different diets using infrared thermometry, measuring hourly from 8 am until 10 pm between late April and early June in Denmark. The CBT ranged from 9.6° to 35.5°C. Coronary band temperature followed a diurnal pattern and was positively associated with ambient temperature - for every 1'C increase in ambient temperature, CBT increased by 0.62'C. Horses had differences in CBT between 2 limbs at the same time of up to 17'C (mean 15.5'C) and changes in CBT measurements an hour apart in the same limb up to 15.7'C. There was no effect of feeding grass containing 1g/kg fructan on CBT. The paper concludes that "In healthy horses, the CBT differed significantly within and among limbs during the course of a day. Changes in CBT followed a diurnal pattern and were positively associated with ambient temperature. These results indicate that caution is advised for the use of CBT for clinical or experimental assessment of hoof disease in horses."
Insulin-Induced Laminitis - An investigation of the disease mechanism in horses by Melody de Laat, Martin Sillence, Catherine McGowan and Christopher Pollitt - RIRDC December 2011 (choose "Download PDF") (see also Equine laminitis: Induced by 48 h hyperinsulinaemia in Standardbred horses de Laat et al. 2010)
Hoof wall surface temperature was monitored in (insulin-sensitive) horses with hyperinsulinaemia-induced laminitis (insulin > 700 µIU/ml) - the ambient temperature was kept constant at all times (15.9 +/- 0.4'C). The HWST varied from around 26'C to 17'C over 48 hours in the control horses, with a gradual decrease in temperature. The HWST in the hyperinsulinaemic horses increased over the first 12 hours from around 22'C to around 27'C then remained elevated (see p13). The elevated HWST results indicate that there is a vascular component to the development of insulin-induced laminitis.
J ANIM SCI November 2007 vol. 85 no. 11 2949-2958
Dietary fructan carbohydrate increases amine production in the equine large intestine: Implications for pasture-associated laminitis
Crawford C, Sepulveda MF, Elliott J, Harris PA, Bailey SR
Hoof wall and coronary band temperatures were recorded after acclimatising the ponies for an hour in a temperature-controlled room (20'C)
Am J Vet Res. 2005 Apr;66(4):630-6.
Digital blood flow and plasma endothelin concentration in clinically endotoxemic horses.
Menzies-Gow NJ, Bailey SR, Stevens K, Katz L, Elliott J, Marr CM.
"Significant associations were found between an increase in digital pulses, hoof wall temperatures, or both and increased digital blood flow (0.14 vs 0.04 mL/min) on day 2 and increased digital arterial diameter (0.32 vs 0.23 cm) on day 5."
Equine Vet J. 2004 Apr;36(3):267-72.
The effects of vasoactive amines found in the equine hindgut on digital blood flow in the normal horse.
Bailey SR, Menzies-Gow NJ, Marr CM, Elliott J.
"Tryptamine and phenylethylamine infusions had no effect on systemic arterial blood pressure or heart rate, but caused significant decreases in digital arterial blood flow (mean +/- s.e. 29.2 +/- 8.5 and 18.4 +/- 6.8%, respectively). Both amines also caused decreases in dorsal hoof wall temperature (0.6 +/- 0.1 and 0.5 +/- 0.1 degrees C for tryptamine and phenylethylamine, respectively) and concomitant increases in plasma 5-HT concentration."
Am J Vet Res. 2001 Jul;62(7):1167-72.
Evaluation of hoof wall surface temperature as an index of digital vascular perfusion during the prodromal and acute phases of carbohydrate-induced laminitis in horses.
Hood DM, Wagner IP, Brumbaugh GW.
"Determination of HWST is a valid technique to evaluate digital perfusion under appropriate controlled conditions in horses. Digital hypothermia detected during the prodromal phase of laminitis is consistent with decreased digital vascular perfusion or metabolic activity."
Pollitt CC, Davies CT
Equine laminitis: its development coincides with increased sublamellar blood flow
Equine Vet J Suppl. 1998 Sep;(26):125-32
Laminitis was induced by starch overload (sepsis-related laminitis) and hoof temperature measured in horses kept in an environmental chamber at 10'C, and compared to controls. "Recording hoof temperature was a successful, noninvasive, method to measure indirectly, shifts in digital blood flow against a background of cold induced, physiological, vasoconstriction. High hoof temperatures were assumed to indicate digital vasodilation and low hoof temperatures digital vasoconstriction....Analysis of mean hoof temperature graphs showed that horses judged laminitis positive (from histological evidence) had experienced a period of prolonged digital vasodilation 16-40 h after carbohydrate overload. Laminitis negative horses experienced no such period of vasodilation and never had hoof temperatures significantly (except once, at 28 h) above that of controls. The only parameter which significantly differentiated the laminitis positive from laminitis negative horses, between 12 and 32 h after carbohydrate overload, was foot temperature, which was significantly higher in laminitis positive horses (P < 0.05). Therefore, a period of sublamellar vasodilation, 12 to 40 h after alimentary carbohydrate overload precedes the onset of laminitis."
Equine Vet J. 1992 Mar;24(2):134-9.
Hoof and distal limb surface temperature in the normal pony under constant and changing ambient temperatures.
Mogg KC, Pollitt CC.
"It was concluded that clinical interpretation of limb surface temperatures in ponies required an awareness of ambient temperature conditions."
See also Thermography.
Increased hoof/hoof wall surface temperature has been recorded in experimentally induced laminitis cases (sepsis-related and hyperinsulinaemia-associated). However, horses without laminitis can have fluctuations in hoof temperature throughout the day, with differences being measured between feet.
The measurement of HWST has been validated as a non-invasive index of blood flow in the foot by researchers, but under ambient temperature-controlled conditions.
Rosenmeier JG, Strathe AB, Andersen PH
Evaluation of coronary band temperatures in healthy horses
Am J Vet Res. 2012 May;73(5):719-23. doi: 10.2460/ajvr.73.5.719
4,320 coronary band temperatures (CBT) were obtained from 6 healthy, unshod, stalled horses fed different diets using infrared thermometry, measuring hourly from 8 am until 10 pm between late April and early June in Denmark. The CBT ranged from 9.6° to 35.5°C. Coronary band temperature followed a diurnal pattern and was positively associated with ambient temperature - for every 1'C increase in ambient temperature, CBT increased by 0.62'C. Horses had differences in CBT between 2 limbs at the same time of up to 17'C (mean 15.5'C) and changes in CBT measurements an hour apart in the same limb up to 15.7'C. There was no effect of feeding grass containing 1g/kg fructan on CBT. The paper concludes that "In healthy horses, the CBT differed significantly within and among limbs during the course of a day. Changes in CBT followed a diurnal pattern and were positively associated with ambient temperature. These results indicate that caution is advised for the use of CBT for clinical or experimental assessment of hoof disease in horses."
Insulin-Induced Laminitis - An investigation of the disease mechanism in horses by Melody de Laat, Martin Sillence, Catherine McGowan and Christopher Pollitt - RIRDC December 2011 (choose "Download PDF") (see also Equine laminitis: Induced by 48 h hyperinsulinaemia in Standardbred horses de Laat et al. 2010)
Hoof wall surface temperature was monitored in (insulin-sensitive) horses with hyperinsulinaemia-induced laminitis (insulin > 700 µIU/ml) - the ambient temperature was kept constant at all times (15.9 +/- 0.4'C). The HWST varied from around 26'C to 17'C over 48 hours in the control horses, with a gradual decrease in temperature. The HWST in the hyperinsulinaemic horses increased over the first 12 hours from around 22'C to around 27'C then remained elevated (see p13). The elevated HWST results indicate that there is a vascular component to the development of insulin-induced laminitis.
J ANIM SCI November 2007 vol. 85 no. 11 2949-2958
Dietary fructan carbohydrate increases amine production in the equine large intestine: Implications for pasture-associated laminitis
Crawford C, Sepulveda MF, Elliott J, Harris PA, Bailey SR
Hoof wall and coronary band temperatures were recorded after acclimatising the ponies for an hour in a temperature-controlled room (20'C)
Am J Vet Res. 2005 Apr;66(4):630-6.
Digital blood flow and plasma endothelin concentration in clinically endotoxemic horses.
Menzies-Gow NJ, Bailey SR, Stevens K, Katz L, Elliott J, Marr CM.
"Significant associations were found between an increase in digital pulses, hoof wall temperatures, or both and increased digital blood flow (0.14 vs 0.04 mL/min) on day 2 and increased digital arterial diameter (0.32 vs 0.23 cm) on day 5."
Equine Vet J. 2004 Apr;36(3):267-72.
The effects of vasoactive amines found in the equine hindgut on digital blood flow in the normal horse.
Bailey SR, Menzies-Gow NJ, Marr CM, Elliott J.
"Tryptamine and phenylethylamine infusions had no effect on systemic arterial blood pressure or heart rate, but caused significant decreases in digital arterial blood flow (mean +/- s.e. 29.2 +/- 8.5 and 18.4 +/- 6.8%, respectively). Both amines also caused decreases in dorsal hoof wall temperature (0.6 +/- 0.1 and 0.5 +/- 0.1 degrees C for tryptamine and phenylethylamine, respectively) and concomitant increases in plasma 5-HT concentration."
Am J Vet Res. 2001 Jul;62(7):1167-72.
Evaluation of hoof wall surface temperature as an index of digital vascular perfusion during the prodromal and acute phases of carbohydrate-induced laminitis in horses.
Hood DM, Wagner IP, Brumbaugh GW.
"Determination of HWST is a valid technique to evaluate digital perfusion under appropriate controlled conditions in horses. Digital hypothermia detected during the prodromal phase of laminitis is consistent with decreased digital vascular perfusion or metabolic activity."
Pollitt CC, Davies CT
Equine laminitis: its development coincides with increased sublamellar blood flow
Equine Vet J Suppl. 1998 Sep;(26):125-32
Laminitis was induced by starch overload (sepsis-related laminitis) and hoof temperature measured in horses kept in an environmental chamber at 10'C, and compared to controls. "Recording hoof temperature was a successful, noninvasive, method to measure indirectly, shifts in digital blood flow against a background of cold induced, physiological, vasoconstriction. High hoof temperatures were assumed to indicate digital vasodilation and low hoof temperatures digital vasoconstriction....Analysis of mean hoof temperature graphs showed that horses judged laminitis positive (from histological evidence) had experienced a period of prolonged digital vasodilation 16-40 h after carbohydrate overload. Laminitis negative horses experienced no such period of vasodilation and never had hoof temperatures significantly (except once, at 28 h) above that of controls. The only parameter which significantly differentiated the laminitis positive from laminitis negative horses, between 12 and 32 h after carbohydrate overload, was foot temperature, which was significantly higher in laminitis positive horses (P < 0.05). Therefore, a period of sublamellar vasodilation, 12 to 40 h after alimentary carbohydrate overload precedes the onset of laminitis."
Equine Vet J. 1992 Mar;24(2):134-9.
Hoof and distal limb surface temperature in the normal pony under constant and changing ambient temperatures.
Mogg KC, Pollitt CC.
"It was concluded that clinical interpretation of limb surface temperatures in ponies required an awareness of ambient temperature conditions."
See also Thermography.
Hops
Harlow BE, Lawrence LM, Flythe MD
Effects of hops (Humulus lupulus L.) β-acid extract on inulin fermentation by equine fecal microflora in vitro
Journal of Equine Veterinary Science , Volume 33 , Issue 5 , 337
DeepDyve
Harlow BE, Lawrence LM, Flythe MD
Effects of hops (Humulus lupulus L.) β-acid extract on inulin fermentation by equine fecal microflora in vitro
Journal of Equine Veterinary Science , Volume 33 , Issue 5 , 337
DeepDyve
Hyperhidrosis - excessive sweating
Hyperhidrosis (excessive sweating) is seen in some horses with PPID. According to Harold Schott (Pathogenesis and diagnosis of equine Cushing's disease
(Proceedings) Apr 1, 2010) this is commonly seen over the neck and shoulder areas. Anecdotally, the sweating is often patchy, often on just one side of the horse, and is often reported on the belly as well as the neck and shoulders.
The reason for hyperhidrosis in PPID is not fully understood, but suggestions include:
physical pressure of the enlarged pars intermedia on the thermoregulatory centre of the hypothalamus,
thermoregulatory response to the long hair coat (but PPID horses that are clipped or in a cool environemnt continue to sweat),
effect of increased beta-endorphin.
Abra Wright MSc Thesis 2009 (page 7)
Pharmacokinetics of Pergolide in normal mares
For less sweating than normal see Anhidrosis.
The reason for hyperhidrosis in PPID is not fully understood, but suggestions include:
physical pressure of the enlarged pars intermedia on the thermoregulatory centre of the hypothalamus,
thermoregulatory response to the long hair coat (but PPID horses that are clipped or in a cool environemnt continue to sweat),
effect of increased beta-endorphin.
Abra Wright MSc Thesis 2009 (page 7)
Pharmacokinetics of Pergolide in normal mares
For less sweating than normal see Anhidrosis.
Hyperlipaemia
Ponies, miniatures and donkeys are particularly prone to hyperlipaemia if they stop eating.
Vet Rec. 1985 Apr 27;116(17):461-6
Current concepts of hyperlipaemia in horses and ponies
Jeffcott LB, Field JR
What do you know about hyperlipaemia? - The Donkey Sanctuary
Hyperlipemia and Hepatic Lipidosis in Horses, Donkeys, and Camelids - The Merck Veterinary Manual
Hyperlipemia in Miniature Horses by Mary Boyce
Vet Rec. 1985 Apr 27;116(17):461-6
Current concepts of hyperlipaemia in horses and ponies
Jeffcott LB, Field JR
What do you know about hyperlipaemia? - The Donkey Sanctuary
Hyperlipemia and Hepatic Lipidosis in Horses, Donkeys, and Camelids - The Merck Veterinary Manual
Hyperlipemia in Miniature Horses by Mary Boyce
Hypertrichosis/hirsutism and hair coat changes
|
Hirsutism (hypertrichosis) - an abnormally long, thick, often curly coat that fails to shed - is considered the most unique and specific clinical sign of PPID, and therefore diagnostic of the illness, but is now considered an advanced sign of PPID and may be one of the last signs to be seen.
More subtle changes to the hair coat often develop before hirsutism:
A lightening in coat colour may be seen in horses with darker coats. The reason for hair coat changes is not known, but suggestions include: pressure on the hypothalamic thermoregulatory centre by the enlarged pituitary gland (Menzies Gow 2006); increased α-MSH secretion (Lloyd Inc 2008) from the pars intermedia through loss of dopaminergic inhibition; excessive plasma cortisol (Menzies Gow 2006) (but plasma cortisol is often normal when tested); excessive melatonin (Menzies Gow 2006); increased production of androgens by the adrenal glands (Lloyd Inc 2008). |
Int J Trichology. 2010 Jan-Jun; 2(1): 30–35. (Full paper)
Endocrinology of Hirsutism (in humans) Daisy Kopera, Elisabeth Wehr, Barbara Obermayer-Pietsch In humans, hirsutism is linked to PCOS, excessive androgens, severe insulin resistance, excess ACTH, Cushing's syndrome, hyperprolactinemia, use of corticosteroids, ovarian and adrenal tumours. 
A horse with advanced PPID clipped for comfort, but note the long curly hairs on his legs.
|
Abra Wright MSc Thesis 2009 (page 7)
Pharmacokinetics of Pergolide in normal mares
J Vet Diagn Invest. 2007 Jan;19(1):128-32. (PubMed)
Hypertrichosis in a horse with alimentary T-cell lymphoma and pituitary involvement.
Mitsui I, Jackson LP, Couëtil LL, Lin TL, Ramos-Vara JA.
"At necropsy, the mare had hypertrichosis and the pituitary gland was diffusely enlarged. Histologically, neoplastic lymphocytes infiltrated the gastrointestinal mucosa, mesenteric lymph nodes, and the pituitary gland. In addition, there was hyperplasia of the pituitary gland pars intermedia. Pituitary adenoma was not present. Hypertrichosis in this case could have been triggered by a combination of adenomatous hyperplasia of pars intermedia and lymphoma resulting in disruption of the hypothalamic dopaminergic tone or disruption of the hypothalamic thermoregulatory center."
NB PPID does not usually involve lymphoma - this is thought to be the first report of lymphoma affecting the pituitary gland of a horse.
Is an abnormal haircoat always diagnostic of PPID?
No - according to Dianne McFarlane a long haircoat is not an absolute diagnosis of PPID - it is highly suggestive in an old horse but other things can cause the haircoat to not shed appropriately. She has found that horses that are very debilitated/malnourished may test positive for PPID and show clinical signs of PPID including not shedding normally, but once they are back to a good weight and more healthy they no longer test positive for PPID, shed their coat normally, and when their pituitary glands have been examined at post mortem they have been normal. She suggests that the stress of being debilitated may affect their endocrine axis and affect their haircoat.
See Is it PPID or is it EMS?
Pharmacokinetics of Pergolide in normal mares
J Vet Diagn Invest. 2007 Jan;19(1):128-32. (PubMed)
Hypertrichosis in a horse with alimentary T-cell lymphoma and pituitary involvement.
Mitsui I, Jackson LP, Couëtil LL, Lin TL, Ramos-Vara JA.
"At necropsy, the mare had hypertrichosis and the pituitary gland was diffusely enlarged. Histologically, neoplastic lymphocytes infiltrated the gastrointestinal mucosa, mesenteric lymph nodes, and the pituitary gland. In addition, there was hyperplasia of the pituitary gland pars intermedia. Pituitary adenoma was not present. Hypertrichosis in this case could have been triggered by a combination of adenomatous hyperplasia of pars intermedia and lymphoma resulting in disruption of the hypothalamic dopaminergic tone or disruption of the hypothalamic thermoregulatory center."
NB PPID does not usually involve lymphoma - this is thought to be the first report of lymphoma affecting the pituitary gland of a horse.
Is an abnormal haircoat always diagnostic of PPID?
No - according to Dianne McFarlane a long haircoat is not an absolute diagnosis of PPID - it is highly suggestive in an old horse but other things can cause the haircoat to not shed appropriately. She has found that horses that are very debilitated/malnourished may test positive for PPID and show clinical signs of PPID including not shedding normally, but once they are back to a good weight and more healthy they no longer test positive for PPID, shed their coat normally, and when their pituitary glands have been examined at post mortem they have been normal. She suggests that the stress of being debilitated may affect their endocrine axis and affect their haircoat.
See Is it PPID or is it EMS?
Hypothalamus/Hypothalamic-Pituitary Gland Axis
Vet Clin Equine 27 (2011) 1–17 (Full)
Hypothalamic-Pituitary Gland Axis Function and Dysfunction in Horses
Samuel D A Hurcombe
Hypothalamic-Pituitary Gland Axis Function and Dysfunction in Horses
Samuel D A Hurcombe