Probiotics in horses the subject of cutting-edge research


stock-foal-rest-tired_6127Manipulating gut bacteria to maintain good health and prevent disease through probiotic use represents cutting edge medical research, says a high-profile nonprofit foundation which backs animal research.

The US-based Morris Animal Foundation says probiotic awareness and supplementation, whether through food or supplements, is becoming more common in people and small animals, such as cats and dogs, and there is growing interest in using them in larger species, including horses.

Horses and their close relatives, including ponies, donkeys and zebras, have digestive tracts that differ in significant ways from not only small animals, but from other grazing animals such as cattle and deer.

Cows and related animals ferment and digest complex foods such as hay and grass at the beginning of their digestive tracts. Once the material has been subjected to breakdown by bacteria, the rest of a cow’s digestive tract is fairly similar to animals such as the pig, cat and dog.

Horses have almost the opposite digestive tract set up; their stomach and small intestine are similar to humans, dogs and cats, but the business end of their digestive tract is, well, at the other end. As researchers learn more about how gut bacteria influence health and disease in small companion animals, equine veterinarians also are exploring how gut bacteria affect important horse diseases such as foal pneumonia, laminitis and colic.

Horses digest fiber in their large intestine, which is huge compared to other companion animals, and comes toward the end of the digestive journey. Like cattle, resident bacteria in the large intestine ferment fiber and release nutrients that are important sources of energy for horses. How these bacteria, and the balance of different bacteria in the large intestine, may impact disease and health, is the subject of ongoing research.

The foundation has funded several research projects that have increased knowledge of how this complex population affects the health of horses. One project noted how the bacteria change in conditions similar to starch-induced laminitis and identified bacteria that could be beneficial as probiotics.

Another described the bacterial population found in foals, and how it changed over time. Newborn foals were found to have a rich and diverse bacterial community, mainly comprised of the Firmicutes phylum with several low abundant genera being unique at this age.

Foals aged 2–30 days had significantly decreased diversity compared to older animals but, after 60 days of life, the intestinal microbiota structure tended to remain stable. However, differences in community membership were still present between 9-month-old animals and mature mares.

Several differences at the phylum level were observed between different ages, including a higher abundance of Fibrobacteres after weaning.

Ongoing studies include a further look at how the microbiome influences starch metabolism in the hope of identifying bacterial factors that contribute to serious and often fatal diseases such as diarrhea, colic and laminitis.

Overconsumption of carbohydrates is known to increase bacterial fermentation, microbial by-products and acidity in a horse’s gut that can lead to these potentially devastating disorders.

Dr Jan Janecka, of Texas A&M University, is leading research to examine how hindgut bacteria respond to increased carbohydrate ingestion in order to identify bacterial factors that may contribute to development of these various disorders. The information may ultimately lead to novel preventive practices or treatments.

The Morris Animal Foundation funds scientific studies for companion animals, horses and wildlife. Since 1948 it has put more than $US100 million toward 2400 studies that have led to significant breakthroughs in diagnostics, treatments, preventions and cures to benefit animals worldwide.

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