Colin Mitchell BVM&S CertEP MRCVS Scott Mitchell Associates Laminitis Colin Mitchell BVM&S CertEP MRCVS Scott Mitchell Associates

Content 1. What is laminitis? 2. What causes laminitis? 3. Signs of laminitis. 4. Treatment of laminitis. 5. Management and prevention strategies.

What is laminitis ? “itis” = “inflammation” “laminae” = “a thin flat membrane” So… “inflammation of a membrane in the horses foot” Debilitating, sometimes devastating disease.

Where are the laminae? The structures that connect the hoof wall to the pedal bone

Structure of the foot……..

Structure of the foot……..

Structure of the foot…… The pedal bone is housed within the hoof capsule It’s the laminae which hold the two together

The laminae Arranged in vertical rows from the coronary band running down to the ground

The laminae Insensitive layer on inside of hoof wall Sensitive layer next to pedal bone

laminitis It’s a very sensitive and well organised network Hoof laminae Pedal bone laminae

laminitis When there is inflammation of the laminae, they swell Then they weaken. Hoof laminae Pedal bone laminae

In mild cases this may not occur In severe cases the pedal bone will be pushed out of alignment and possibly through the bottom of the foot

What causes laminitis? 1. Too much…. 2. The sick horse 3. Other causes A. grass B. grain C. Weight (obesity) 2. The sick horse Severe infections Post foaling problems Cushing’s disease 3. Other causes Concussion Excessive weight bearing foot Stress / Drugs / Cold weather Most causes are nutrition related

The Digestive System Sugars and starch are broken down in the large intestines by good bacteria

A. Too much…. GRASS Take a field

A. Too much…. GRASS add the sun

A. Too much…. GRASS Plenty rain

A. Too much…. GRASS And…. Fresh new grass, full of sugars

A. Too much…. GRASS Add a horse

A. Too much…. GRASS A 500kg horse can And Eat 65kg grass a day That’s 3kg sugar! And

A. Too much…. GRASS Grass growing quickly has large amount of fructans in. - produced by photosynthesis. But horses can’t break it down

cereals are high in starch….. B. Too much ……GRAIN Any overfeeding can cause laminitis :- Daily overfeeding by owner Raiding the feed bin cereals are high in starch….. Current thinking that XS protein does not cause laminitis

Fructans and (excess) starch Not broken down by bacteria in the horse’s caecum Rapidly fermented in the horse’s gut causing an acid environment. This kills the good bacteria ACID

Fructans and (excess) starch endotoxins. constrict Aaargh!! ACID

Loss of blood supply to the feet Cells die Signs of disease, heat, pain etc

C. Too much weight (obesity) Metabolic Intestinal environment

C. Too much weight (obesity) A horse in good condition Rounded rump Ribs felt easily but not seen Fit not fat Lean not thin

2. The sick horse Any disease that causes horses to be sick can cause laminitis Release of toxins into the blood stream We look for the underlying cause river

2. The sick horse Post-foaling, mares with retained afterbirths Endotoxins

3. Other causes Concussion

4. Other causes Excessive weight bearing

Equine Cushing’s Syndrome Common problem in older horses and ponies (average 19yo) Hormonal abnormality which leads to many and varied clinical signs Laminitis Long curly coat Weight loss/redistribution Lethargy Drinking/urinating too much Bulging fat pads above the eyes Susceptible to infections Requires life long management (expensive)

Causes of Cushing’s disease Growth of pituitary gland in the brain Lack of ‘Dopamine inhibition’ from the hypothalamus Leads to excess of ACTH Production of excess cortisol by the adrenal glands on the kidneys Circulates around the body causing trouble!

Equine Metabolic Syndrome Poorly understood condition Cortisol is produced by fat cells in the abdomen Related to body’s inability to use its own insulin, and regulate glucose levels “insulin resistance” – like obese people Young, fit or overweight horses Severe laminitis, unresponsive to therapy

(3) Signs of laminitis Try and pick up cases as early as possible History Stance of the horse Heat in the feet? Increased/bounding digital pulses Evidence of ‘founder’

Clinical Picture

Clinical Picture ‘Obel grading’ 0 – no lameness at trot on hard surface 1 – Stilted in trot on hard surface and on turn 2 – Stiff at walk and doesn’t like turning 3 – Reluctant to walk on hard surface and difficult to lift leg 4 – May lie down, coercion to move especially on hard surfaces

Digital Pulses Can be felt at the fetlock or at the back of the pastern It is personal preference which site is used but remember that the horses pulse is slow and you may not feel every pulse initially so keep feeling for a while!

Evidence of ‘founder’

Radiography – X-rays Used to monitor the progress of the condition – may need to take several sets over time

Radiography Normal Dorsal hoof wall and pedal bone parallel and no evidence of ‘founder’ Normal 10-15 degree angulation of the bottom of the pedal bone with the sole of the foot Horse still shod

Radiography Mild changes Small divergence between dorsal hoof wall and pedal bone Increased angle of the bottom of the pedal bone to the sole of the foot

Radiography Moderate changes Wide gap developing between the hoof wall and pedal bone Evidence of ‘founder’ or sinking of the pedal bone Further increase in the angle of the pedal bone to the sole

Radiography Moderate/severe changes Again we see rotation and founder with the tip of the pedal bone now very close to the sole of the foot

SEVERE CASE Pedal bone rotated and dropped to the point of emerging through the bottom of the sole of the foot

First aid Treatment Remove initiating factor Box rest Deep bed or sole support Feeding – good quality forage. Don’t starve

Sole support

Styrofoam pads Styrofoam pads – similar action to sole support system whereby foam moulds to the feet to supply good support

Veterinary / farrier treatment Pain relief Improve circulation Sole support Foot trimming/Dorsal wall resection Abscess treatment

Pain Relief

Improving Circulation Vasodilators – drugs which have a direct action to open up blood vessels supplying the laminae Acepromazine – ACP Isoxuprine Glyceryl trinitrate Anticoagulants – drugs which prevent small blood clots forming in the circulation Aspirin Heparin

Foot trimming Attempt to re-establish the normal position of the pedal bone within the foot

Dorsal wall resection Salvage procedure used when more conservative methods have failed Removal of the front (or dorsal) wall of the hoof completely This eliminates the forces acting to pull apart the laminae from the pedal bone at the front of the foot

1. Avoid obesity Avoid your horse getting too fat Should not have fat deposits around the crest, tail head, sheath, udder You should be able to feel ribs Trevor. Lost 50kg

Feed according to work done If horses are fed calories in excess to their daily requirements they will put on weight exercise calories

Use a weight tape Maintain your horse at a sensible weight Weigh out the hay and hard feed

2. Avoid over eating Foods rich in sugars or starches Cereals, cereal based feeds, coarse mix, rapidly growing grasses If you do use them, feed little and often

Restrict access to grazing For susceptible horses, not every horse Esp. spring & autumn Remove droppings frequently to avoid worms Limit time out Grazing muzzles

Feeding for extra work When you do need more energy dense feeds Use high fibre, low starch feeds Consider using soya or corn oils – slow release energy Oil is safer as it contains no sugars or starch. Rupert

4. Probiotics Friendly bacteria Improves fibre digestion

Founderguard Virginiamycin In feed antibiotic Reduces acid build up during fermentation of starch and sugar

Methionine/Biotin supplementation Promotes good horn growth by supplying the building blocks which may be lacking Long term improvement – takes 9 months for new horn to grow out Improved quality and strength of hoof should help chronic laminitic horses Different preparations available but all similar and perform the same task

5. Avoid the other causes Excessive concussion on roads Feet regularly trimmed and balanced Treat other diseases Illnesses that cause toxaemias Cause of weight bearing laminitis Cushing’s disease