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Is Chronic Laminitis in Horses Related to Bacterial Infection?By Kentucky Equine Research Staff · June 2, 2015

Horses can develop laminitis as a result of inflammation triggered by consumption of starch that overwhelms digestion in the small intestine and affects fermentation and microbial balance in the hindgut. This starch overload may come from large grain meals or from consumption of lush pasture grass that contains high levels of fructans. Researchers in the Department of Biochemistry and Microbiology at Rutgers University have noted some parallels between humans with metabolic syndrome and horses that develop laminitis. They have hypothesized that pasture-induced laminitis might develop as a result of exposure to potential bacterial pathogens that are present in pasture grass and are ingested as horses graze.

The objective of the study was to determine whether horses with chronic laminitis can have undiagnosed laminar infections without an active hoof abscess. A first step was to look for bacteria in the laminar tissues of horses with chronic laminitis and also unaffected horses.

Results showed that horses with chronic laminitis had higher numbers of bacteria in their laminar tissues than nonlaminitic horses. These bacteria were of types that live in soil and water. Laminar tissue from horses with laminitis induced by carbohydrate overload did not show higher levels of these bacteria, but they did show diarrhea and fever consistent with intestinal infections.  

A review of 20 years of veterinary records for 200 Rutgers University research horses showed that that no horses had developed laminitis although they were pastured year-round with supplemental hay fed in the winter months. These horses, mostly Standardbred mares, might be genetically resistant to the factors that trigger laminitis, including persistent bacterial infections. Treating laminitis with antibiotics is not advised and can lead to the rise of antibiotic-resistant bacterial strains.  

Laminitis continues to be a problem for large numbers of horses, and many different factors may be implicated as causes of this disease. Continuing research may help to uncover more information that will aid in preventing and treating this crippling condition.  

Kathleen Crandell, Ph.D., an equine nutritionist for Kentucky Equine Research, said that gastrointestinal disturbances related to overconsumption of carbohydrates are known to trigger laminitis. Using a timed-release hindgut buffer such as EquiShure can lower the risk of laminitis caused by changes in intestinal acidity. EquiShure is designed to act on the cecum and colon, minimizing the effects of subclinical hindgut acidosis.