What is it?
Laminitis, or equine founder, is a painful and potentially devastating foot condition. Founder is an emergency; call your vet immediately if you suspect founder.
What are the symptoms?
Early symptoms of equine founder are often subtle. The horse may be slightly stiff, particularly the forelegs. Laminitis causes severe heat in the feet, a strong digital pulse and a “rocking-horse” posture, as the horse leans back on his heels to relieve pain.
He will be reluctant to walk. He may lie down and not want to get up. If forced to stand however, he will will lean back on his heels and shift weight from one affected foot to the other. Founder most often occurs in the front hooves, but can occur in all four.
Where does it come from?
The most common cause of equine founder in grazing horses is unrestricted access to lush pasture, especially after being kept inside for the winter. In most parts of the country, the risk for pasture-associated laminitis, or “grass founder,” is highest in the spring and early summer, when plant growth is greatest and levels of fructan are highest. Fructan is a starch-like compound that cannot be digested in the foregut by enzymes. It therefore enters the cecum where it is rapidly fermented, causing changes in the microbial climate of the intestines. These changes lead to the release of bacterial toxins into the bloodstream. It is thought that these toxins disrupt normal blood flow to the hoof, causing laminitis.
The fructan content of grasses varies according to the type of grass, stress on the plants, fertilization and hydration of the plants, climate, and even time of day. If a horse has foundered in a specific pasture setting, fructan content should be considered, and horses removed from that location.
Although far less common, grass founder can occur any time rainfall, sunlight, and daytime temperatures are sufficient to stimulate rapid plant growth.
Other possible causes of equine founder include:
• Unbalanced hooves due to poor hoof trimmingpractices
• Potomoc horse fever
• Colitis caused by Salmonella sp. bacteria
• Stress resulting from constant movement, shipping, showing, loss of sleep or equine dehydration
• Accidents or mechanical trauma
• Black-walnut shavings used as bedding
• Carbohydrate overload due to excess grain consumption
• Insulin resistance and/or obesity
• Nitrogen compound overload due to consumption of artificially fertilized pasture
• Over-consumption of nitrate accumulating pasture weeds like clover
• Too much time spent on hard ground
• A bout of severe colic
• Equine cushings disease
• Drug reactions, especially corticosteroids (anecdotal)
• Exposure to agro-chemicals
How is it diagnosed?
Contact your vet immediately if your horse shows signs of lameness. The sooner grass founder is diagnosed and treated, the better the outcome. The most important diagnostic sign to watch for is a change in the nature of the digital pulse. Become familiar with the normal feel of your horse’s digital pulse! Heat in the hoof is also a typical sign, but not as reliable as digital pulse.
How is it treated?
Move the horse to a paddock with very little or no feed (but avoid over stressed pastures which may be high in fructan), remove grain from the diet and feed only hay and water.
Phenylbutazone (Bute) is often prescribed, but this may encourage the horse to move more than it should, causing further damage. Pain control must be carefully administered while the horse is restrained in a well bedded stall to prevent excessive activity.
Do not force a horse to walk if it is clearly in pain and reluctant to move.
Horses with laminitis need specific amino acids, fatty acids, vitamins and minerals to re-grow damaged hoof tissues. They should not be starved as therapy. Remove all grains and starchy feeds immediately. Then make changes in feeds slowly. Minimize stress to the hindgut by feeding highly digestible fibers, vegetable oils as needed, and balanced protein, vitamins and minerals.
How is it prevented?
Preventing equine founder is simple: limit the horse’s access to lush pasture, particularly during the high-risk hours between late morning and late afternoon.
During periods of lush growth, keep the horse in a dry lot and feed good quality grass hay.
Use a grazing muzzle.
Soak hay to remove excess sugars. Feed horses 1/2 before turnout and limit time on pasture.