Laminitis – one of the most dreaded conditions by horse owners – is a painful and life-threatening condition of the feet of the horse. Inflammation in the structures that connect the hoof capsule to the coffin bone causes pain and damage inside the foot. Left undiagnosed or untreated, it can result in the hoof wall separating from the underlying coffin bone. If this happens, the bone can sink through the bottom of the foot, leading to euthanasia. Laminitis can occur in your horse from many causes and should always be considered an emergency.
Conditions That Increase the Risk of Developing Laminitis
A. Endocrine Conditions
1. PPID (Equine Cushings)
Horses in their twenties should be screened for PPID yearly. An older horse diagnosed with PPID should be placed on medication (Prascend) to control the disease and help prevent the onset of laminitis. Horses with Cushings are slow to shed in the spring, lose muscle mass along the topline and show changes in their haircoat where the hair may be longer than usual and wavy. They can have trouble staying warm in the winter and cool in the summer. Some affected horses drink more water and urinate more frequently.
2. Equine Metabolic Syndrome (Insulin Resistance):
Horses can develop this condition at any age, but typically it appears in the prime of life. Overweight horses and horses with a genetic predisposition are the most likely candidates. Their body loses the ability to store fat properly and to regulate insulin properly. In our practice, we monitor your horse's weight and fat distribution. If these become abnormal, a blood sample to measure insulin levels and a weight loss strategy will be recommended. Properly controlling insulin is an essential means of reducing the risk of laminitis.
A. Diet:
Horses evolved over millions of years as grazers and browsers. For everything to work as designed, horses must consume small portions of forage throughout the day as they walk over the terrain. The plants on the free-ranging landscape are low in starch and sugars and high in fiber. When we contrast the natural diet to the captivity diet of our horses, we see that our domesticated horses consume a large amount of feed quickly, which may be high in starch and sugar. Large meals move much more rapidly through the gut than small meals. Rapid transit from the stomach and small intestine limits the ability of the horse to remove the sugars and starches and deliver these nutrients in more significant amounts to the colon (hindgut). The problem can begin with the overflow of highly fermentable sugars and starches to the fermentation vat of the hindgut. Large amounts of starch or sugar in the colon frequently upset the finely tuned microbiome, which can result in the death of helpful bacteria and promote the growth of harmful bacteria. The by-products of this disturbance can cause colic and affect the colon's lining to the extent that toxic inflammatory products such as endotoxin escape into the system, adding to an acute case of laminitis.
Grain should be fed in small amounts, if at all. We advise meeting your horse's energy requirements in other ways. If grain (oats, barley, or corn) is needed, don't feed over 3 lbs. per meal.
B. Road Founder:
Some horses can develop laminitis-like symptoms from being overworked on hard surfaces. Similar symptoms are seen in horses when the feet are trimmed too short by the farrier, especially when the sole is removed with the hoof knife. These cases usually resolve with treatment and do not become a chronic condition.
C. Infection/Sepsis:
Laminitis caused by sepsis/infection results from primary inflammatory conditions such as pneumonia, intestinal injury in severe colic, uterine infections that arise from retained placental tissue in the uterus after foaling, and severe diarrhea. Toxic products resulting from these infections are absorbed in the blood and delivered to the feet, where they cause inflammation and weaken the attachment of the coffin bone to the hoof wall.
D. Black Walnut Toxicity:
The toxic substance in black walnuts that causes laminitis is unknown. Exposure to black walnut toxicity is usually through contact with black walnut shavings. Shavings that contain as little as 20% fresh black walnut shavings will induce laminitis. Aged shavings or composted shavings produce less risk. Investigators believe the toxin is absorbed through the skin. Symptoms of exposure include colic, swollen legs, and lameness due to laminitis.
E. Supporting Limb Laminitis:
Non-weight-bearing of one limb for protracted periods often develop laminitis in the other limb. How long it takes to contract laminitis in the opposite limb depends on many factors and can only be estimated individually. Overweight horses, horses with previous episodes of laminitis, horses with Cushings (PPID), and horses with equine metabolic syndrome will contract laminitis sooner rather than later. The goal of treating any severe limb injury should result in weight bearing as soon as possible.
F. Medication:
Steroid medications have been shown to induce laminitis in some individuals. Dexamethasone and triamcinolone are more potent and are more likely to cause laminitis than prednisolone.
G. Colid/Diarrhea:
Colic, colic surgery, and diarrhea are significant causes of generalized inflammation in the body. Inflammation can weaken the hoof's attachment to the underlying bone and result in laminitis.