Laminitis

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Laminitis

What is laminitis?
What causes laminitis?
Symptoms of laminitis
Symptoms of chronic laminitis - rotation/sinking
Emergency treatment for laminitis
Management of laminitis
FAQs
Further information - websites
Further information - books and articles
Laminitis Research

Laminitis, EMS & PPID slide show

What is laminitis?

Download our Laminitis, EMS & PPID summary

Laminitis used to be defined as inflammation of the laminae, or lamellae (the laminae/lamellae are "velcro-like" connections between the pedal/coffin bone and the hoof) - "-itis" means inflammation. However, now we know that the majority of cases of laminitis have an endocrine cause, and there may be little or no inflammation involved in endocrine laminitis. Therefore laminitis may be defined as damage to or failure of the laminae, which may include stretching or separation of the laminae. Some vets suggest using the term "laminopathy" rather than laminitis.

The laminae connections start to stretch, separate and break down, allowing the pedal/coffin bone and hoof capsule to rotate or sink in relation to each other - this rotation and/or sinking is called founder or chronic laminitis.

Successful treatment is dependent on:
1. Recognising that the horse has laminitis.
2. Identifying and removing/treating the cause.
3. Supporting and realigning the feet as quickly as possible.

With a positive diagnosis, appropriate treatment and management, and good foot care to fully realign any damage and then keep the foot correctly balanced, many horses return to their former use and live healthy long lives.

The symptoms of laminitis are symptoms of pain
and can range in severity from:

no perceptible pain/lameness (sub-clinical laminitis) but evidence of laminar damage, e.g. divergent hoof rings and/or stretched white line is found in the feet, to
mild clinical laminitis where the horse shows a slight shortening of stride, “feels his feet" or is "pottery” on hard or stony ground and finds it difficult to turn but seems normal on soft ground and in straight lines, to
unwilling to walk or pick feet up, shifting weight from foot to foot ("paddling"), strong digital pulse, slightly increased heart and respiration rate, likely still eating, to
total refusal to move or pick up feet, lying down a lot, heart rate may be over 80 bpm, respiration rate may be over 60 breaths/min, sweating, muscles rock hard, CK & AST may be slightly raised. Temperature usually normal unless SIRS laminitis ( guard against dehydration and impaction colic in a horse in severe pain which is not eating & drinking).

NB changes in stance are often noticed but the stance depends on the damage and the feet affected (any or all feet can be affected), and can include:
front feet out in front, hind legs forward under body;
front legs back under body, hind legs forward under body,
front legs back under body, hind legs normal;
normal stance (common when all 4 feet are affected).

What causes laminitis?

3 classes or causes of laminitis are currently recognised:

Endocrinopathic or insulin-related laminitis - due to hyperinsulinaemia/insulin dysregulation (ID)
By far the most common cause of laminitis (around 90% of all laminitis cases), and most common in ponies and "good doer" breeds. Horses will have insulin dysregulation (ID), which can be due to Equine Metabolic Syndrome (a syndrome/collection of risk factors, not a disease, due to a combination of genetics and management). Horses with PPID can also have insulin dysregulation and an increased risk of laminitis. However, the link between PPID and laminitis is not understood, and it may be that some horses with PPID and laminitis have EMS and PPID. Pasture associated laminitis is endocrinopathic laminitis.

Inflammatory or sepsis-related laminitis - "sick horse laminitis"
This laminitis develops when a horse is already seriously ill with an inflammatory/septic illness, such as colitis, septicaemia, peritonitis, retained placenta, and potentially serious cases of carbohydrate/grain overload, such as if a horse breaks into a feed room. The horse will be systemically ill, will usually have a raised temperature and abnormal white blood cell counts and will often have diarrhoea and/or be depressed. Starch, fructan and black walnut shavings have all been used to induce sepsis-related laminitis experimentally. The primary illness must be treated. Icing the feet (cryotherapy) has been found to be very effective at halting the progression of laminitis in horses with a sepsis-related laminitis. More..

Supporting Limb Laminitis (SLL) - "lame horse laminitis"
A severe protracted non-weightbearing lameness, e.g. a fracture or septic joint condition, can cause laminitis in another leg, usually the other leg in a pair. More..
Barbaro, winner of the 2006 Kentucky Derby, fractured his right hind and developed SLL 2 months later. He recovered, but a further operation led to laminitis in both front feet and he was put to sleep.

The use of corticosteroids has also been implicated in causing or worsening laminitis, particularly in horses that are already prone to laminitis (therefore likely have an underlying, and possibly undetected, endocrinopathy). One injection of dexamethasone (20mg/500kg) caused insulin to increase from 166 to 844 IU in previously laminic ponies, 22 to 206 IU in normal ponies in July in ponies kept at pasture - Borer et al. 2010.

Coleman M, Belknap J, Bramlage L, Eades S, Fraley B, Galantino-Homer H, Hunt R, Geor R, McCue M, McIlwraith W, Moore R, Peroni J, Townsend H, White N, Cummings K, Ivanek-Miojevic R, Cohen N
Case Control Study of Pasture and Endocrinopathy-Associated Laminitis in Horses
Equine Endocrinology Summit 2017
"Horses with an obese body condition (BCS ≥ 7), generalized or regional adiposity, a historic diagnosis of an endocrinopathy, and recent glucocorticoid administration were at increased odds of developing PEAL".

Many causes of laminitis have been suggested, but currently only 5 causes have reliably induced laminitis experimentally: starch, black walnut, oligofructose, fructose and insulin:
80 Causes, predispositions, and pathways of laminitis Henry W. Heymering

"What is Laminitis?" video - www.prascend.com

This video, created by Dr Andrew van Eps, of time-lapse x-rays shows the progression over 4 weeks of a sepsis-related laminitis due to Potomac Horse Fever. P3 rotation & sinking, separation of P3 from the dorsal hoof wall and decreasing sole depth are seen. The video was created by Dr Andrew van Eps, the horse was treated at Pennsylvania School of Veterinary Medicine.

Archived webinar from 25 April 2012:
Laminitis Lessons: A Webinar for Every Horse Owner - Don Walsh DVM from the Animal Health Foundation

Equine Laminitis 2012 Update videos from the Animal Health Foundation

Laminitis definitions

Laminitis = damage to or failure of the laminae (inflammation is not significant in most cases of laminitis)

Founder = loss of normal orientation between the hoof capsule and the pedal bone, i.e. rotation or sinking

Distal descent = sinking

Laminae = lamellae

Pedal bone = coffin bone = P3 = third phalanx

Signs of EMS: 1. dip as neck joins withers, 2. enlarged crest, often with "sausage-like" fat deposits, 3. lack of shoulder definition due to obesity.

An aged horse with PPID being cared for by Remus Memorial Horse Sanctuary. Advanced symptoms include long curly coat that isn't shed, weight loss and loss of top line, laminitis, recurrent infections, excess drinking and urination, depression and lethargy.

Symptoms of laminitis

You are unlikely to see all of these signs - consider laminitis (and call your vet) if you horse shows ANY of these symptoms, but be aware that many are also symptoms of other hoof/lameness issues. Perhaps the most reliable and one of the earliest signs is paddling - but a horse with sinking may not paddle. Symptoms will change as laminitis progresses from acute to chronic. Every horse is different and will show different symptoms and different degrees of pain - recognise and investigate any of these signs - too many horses go undiagnosed because the early signs of laminitis are not picked up - the earlier you recognise the symptoms, remove the cause and support the feet, the better the outcome is likely to be.

Feeling “footy” - showing a preference for soft ground, a reduction in stride length on hard ground
Reluctance to turn
Stiff gait - walking on heels
Reluctance to move leading to total refusal to move
Shifting weight from foot to foot (paddling)
Abnormal stance - depends on feet affected and whether rotation or sinking
Reluctance/refusal to pick up feet
Feet feel hotter than usual (but may feel colder than usual)
Muscle tension in the shoulders, back, quarters - AST & CK may be slightly elevated
Bounding digital pulse
Pain on sole pressure between apex of frog and toe
Lying down more than normal
Signs of pain - pulse (>80 bpm?), respiration (> 60bpm?), trembling, sweating, depressed, off food

Horses with distal descent will be reluctant to move, have bounding digital pulses and have a depression at the coronet. They usually stand in a normal stance and may have abnormally cold feet.

See Rosie's case study to see her symptoms of acute laminitis.

Abnormal stance

Bounding digital pulse - take at fetlock or pastern

Wall flare and bruising

Penetration of sole by P3

13' palmar & 14' dorsal rotation, laminar wedge

Abnormal heel growth

Change of angle, hoof rings

Stretched white line

Symptoms of chronic laminitis - rotation/sinking

Radiographs (x-rays) should always be taken when a horse has had, or is suspected of having had, laminitis. Many of the signs of chronic laminitis may not be seen until several weeks after laminar damage occurred, and not all of these signs will be seen - but the presence of any of these signs should be investigated.
See Chronic laminitis for more photos

Radiographic changes - rotation, distal descent
Abnormal hoof growth - heels grow quicker
Hoof rings wider at the heel
Change in hoof wall angle
Flared hoof wall, wall cracks
Bruising/blood in white line or wall
Stretched white line - deep black groove between wall and sole - laminar wedge
Depression just above the coronet - swelling at the coronary band
Bruising on the sole in front of the frog (below tip of P3)
Thin sole (or may be thickened sole)
Bulging/convex/dropped sole
Penetration of sole by pedal bone (P3)
Collateral grooves much deeper at back of frog than at apex.

Emergency treatment for laminitis

call vet (and farrier/trimmer)
remove horse from grass (but move as little as possible/support feet before moving)
confine on deep supportive bedding e.g. sand, sawdust, pea gravel
support the feet if the bedding isn’t sufficient to do this, e.g. with styrofoam, impression material, boots and pads
give NSAIDs e.g. Bute, Danilon, Equioxx for the inflammation & pain (for as short a time as possible)
apply cold therapy to the feet to reduce inflammation and pain (but not if cold-induced laminitis/feet cold)

Management of laminitis

Feed low NSC (<10%) diet based on grass hay (+ protein, minerals, vitamins, linseed?) - do not starve
Diagnose the cause – test blood for insulin & glucose EMS plus ACTH for PPID
Treat the cause - pergolide for PPID, diet and possibly Metformin for EMS
lateral x-rays to assess damage and movement of the pedal bone
trim hooves & realign any rotation ASAP

Prevent and monitor for laminitis

Prevent laminitis by ensuring your horse

is not overweight,
is regularly exercised (as long as feet are correctly aligned and stable),
and if laminitis is a possibility, feed a low sugar/starch diet and restrict grass by using a muzzle, strip grazing or setting up a track, and allow grazing only when sugar levels are likely to be lowest - remember sun = sugar! If in doubt, don't graze! See www.safergrass.org for information about sugar levels in grass.

Daily checks that can help early identification of laminitis:

Walk on hard ground e.g. concrete - does the stride shorten, does he/she seem at all "pottery"?
Turn in a tight circle - normal or reluctant to turn/stiff behind?
Digital pulses - normal?
Regional fat pads - cresty neck, bulges in hollows above eyes, enlarged sheath, fat above tail? Hardening of neck crest or increase in any of these fat deposits can indicate imminent laminitis.

Frequently Asked Questions

Can a horse get laminitis in any foot?
Yes! With the exception of supporting limb laminitis which generally occurs in the foot opposite to the leg that is severely lame, laminitis (both SIRS and endocrine) is systemic (definition: affecting the entire body) and therefore the factors causing laminitis can affect any foot. Laminitis is often less severe in the hind limbs, but in some horses it is more severe in the hind limbs, or even on one side of the horse. It has been proposed that factors affecting which feet are more severely affected include weight bearing, hoof angle, hoof balance. More..

What's the prognosis for recovery from laminitis?
When the cause of the laminitis is identified and removed/treated, and the feet are supported and realigned at the earliest opportunity, the horse has a good chance of making a full recovery and returning to its previous work level. More..

Further information - websites:

No Laminitis! Symptoms of laminitis and emergency action

ECIRHorse Treatment of laminitis

Equine Laminitis Research Unit at the University of Queensland

Equine Laminitis - current concepts (2008) - Chris Pollitt

Equine Laminitis - managing pasture to reduce the risk - Katy Watts & Chris Pollitt

Information on the prevention and treatment of laminitis in horses and Katy Watts’ research into sugar/carbohydrate levels in grass and hay is available at the Safergrass.org website and Safergrass Yahoo group

The HORSE.com fact sheet: Laminitis

Laminitis Research

Research papers relating to laminitis, EMS and PPID are listed by date, subject and author under Research.

https://researchonline.rvc.ac.uk/id/eprint/11852/1/11852.pdf

Patterson-Kane JC, Karikoski NP, McGowan CM
Paradigm shifts in understanding equine laminitis
The Veterinary Journal Volume 231, January 2018, Pages 33-40

Pollard D, Wylie CE, Verheyen KLP, Newton JR
Assessment of horse owners' ability to recognise equine laminitis: A cross-sectional study of 93 veterinary diagnosed cases in Great Britain
Equine Vet J. 2017 Nov;49(6):759-766. doi: 10.1111/evj.12704. Epub 2017 Jul 3
See also: EVJ Podcast, No 21, Aug 2017 – Horse owners’ ability to recognise equine laminitis

A review of recent advances and current hypotheses on the pathogenesis of acute laminitis
A recently published paper by Lisa Katz and Simon Bailey outlines the current thinking that there are likely to be 3 distinct forms of laminitis - inflammatory (SIRS), endocrine and contralateral (supporting) limb laminitis, and suggests that there may be some interplay between the different forms - the full paper is available free online:
Katz LM, Bailey SR
A review of recent advances and current hypotheses on the pathogenesis of acute laminitis
Equine Veterinary Journal Volume 44, Issue 6, pages 752–761, November 2012

Useful resources for Laminitis

Laminitis webcasts and videos

The Humble Hoof podcast with Dr Andrew Van Eps 11 Nov 2019
"In this episode, Dr. Andrew Van Eps delves into new research on laminitis and founder treatment, as well as the importance of prevention. In it, you will hear about the three causes of laminitis, and research into how to approach each cause. Prevention is better than "damage control," and implementing some changes in your horse's diet and lifestyle can make all the difference!"