Many horse owners are familiar with the spring peak in cases of laminitis, which many associate with the rapid growth of high-sugar grasses in the spring. Fall, with its dry pastures and brown grass, is a season most people don’t associate with laminitis. But, what many owners don’t realize is that autumn brings higher rates of the disease as well, particularly for horses that are already at risk.
The greatest hazard of fall laminitis, Brinton says, is that it creeps up on horse owners when it’s not expected.
Recent research points to two likely culprits for this fall spike. The first is cooler nighttime temperatures, which cause higher levels of non-structural carbohydrates (NSC) in pasture grasses. And secondly, horses secrete more adrenocorticotropic hormone (ACTH) as days get shorter and temperatures drop. Both of these lead to elevated insulin levels, a prime cause of laminitis.
As many as 90 percent of laminitis cases are a result of an underlying hormonal condition such as Cushing’s disease (PPID) or equine metabolic syndrome, the equine equivalent of diabetes. Seasonal rise is the term now used to describe the fall rise in ACTH and resulting insulin and glucose fluctuations in horses with PPID. Before a seasonal rise was identified, fall laminitis was often blamed on high sugar and fructan in grasses. But many horses exhibit the same seasonal patterns of laminitis between August and November without access to grass and without any change in their low sugar and starch diet.
Laminitis can be avoided by keeping the horse active and at a healthy weight, maintaining steady or no grain rations, limiting access to grass, and using a grazing muzzle for prolonged turnout. Brinton advises testing the sugar levels in hay and soaking hay for an hour before feeding, which reduces sugar levels by 30%.
Checking on a horse daily is the most important preventive measure, so changes can be caught early. Several simple tests can assess whether a horse is experiencing hoof changes. Walk the horse on hard ground such as concrete. Does the stride shorten, or does he walk gingerly? Turn it in a tight circle. Is it reluctant to turn or stiff behind? Does it lie down more than usual?
An unusual stance, with front legs stretched out, is also a warning sign. Check the digital pulses of the hoof. A strong pulse at back of horse’s fetlock or abnormally warm hoof wall is a sign of inflammation.
Assess the horse’s body condition for regional fat pads, such as a cresty neck, bulges in hollows above the eyes, an enlarged sheath, and fat above the tail. Hardening of the neck crest or an increase in any of these fat deposits can indicate imminent laminitis.
Over time there may be characteristic changes in the growth pattern of the feet. Heels grow faster than toes, growth rings look curved instead of symmetrical and a ridged hoof wall is marked with raised rings.
Brinton emphasizes immediately removing the horse from grass and confining it to an area with deep supportive bedding such as sand or sawdust. The horse will also experience relief from cold therapy such as a cold water bath to the feet to reduce inflammation and pain. Laminitis is an emergency, and warrants a call to the veterinarian.