This article first appeared in the June 2014 issue of Veterinary Practice News. Probiotics have come to the equine market. Companies seem to be “throwing probiotics into everything,” said Joyce Harman, DVM, member of the Royal College of Veterinary Surgeons. “It’s sort of a hot item,” added Dr. Harman, owner of Harmany Equine Clinic Ltd. in Flint Hill, Va. “But that’s a good thing.” Efforts to make probiotics more widely available are being applauded by equine veterinarians like Harman, who has seen the overuse of antibiotics leave her patients’ digestive systems depleted of key bacteria. “Horses are given antibiotics at the drop of a pin,” Harman said. Patients in Harman’s area, Lyme country, may be particularly in need of probiotics, she said. Afflicted horses there tend to get placed on antibiotics for extended periods. In a typical case, Harman will get called out to check a horse that doesn’t look as well as it should, despite being on a good diet, or a horse that has weight loss, diarrhea or constipation with chronically dry stools or stools that have an excessive amount of water. One gelding was presented to her with a history of Lyme disease. The horse had been treated within the last year with 60 days of doxycycline, and appeared to have recovered from the Lyme disease but his stool remained loose, she said. Harman said the horse had soft stools “not quite the texture of cow pie stools,” and others that were normally formed followed by a few that were pure liquid, prompting the horse’s owner to call Harman with the main complaint that the liquid was coating the back of the horse’s legs and tail. “The first thing that I did was to put him on a course of probiotics,” Harman said. “They called back within two weeks and said that his stool is 80 percent better.” Eleanor M. Kellon, VMD, with Equine Nutritional Solutions, said a positive response after probiotics are given can often be seen quickly—if they are used to treat horses with specific issues. “The best candidates are horses with digestive disturbances like bloating, mild discomfort, intermittent loose manure, often intolerant of grain,” Dr. Kellon said. “Improvement is often seen within a week.” Probiotics aren’t likely to be helpful for horses holding a good weight and without digestive issues, Kellon said. “But they are a good place to start with some gastrointestinal problems and to support microbial populations after stressors like long-distance shipping and endurance exercise.” Not all experts are high on probiotics. One person with doubts is Frank Pellegrini, DVM, vice president of veterinary science at Freedom Health LLC of Aurora, Ohio, maker of the digestive conditioner Succeed. Dr. Pellegrini said there is no evidence showing probiotics actually benefit either immune system or GI tract. “Introducing live bacteria, yeast or other microorganisms into a horse’s gut requires understanding what the normal microbial balance is for that animal,” Pellegrini said. “Our own research indicates that there is no single normal array of gut microflora across the species. In fact, we have found that there is a significant array of different bacteria in the horse’s GI tract.” Pellegrini noted that each individual horse develops its own microbial population, and thus its own “normal balance.” “As a result, the chance of administering probiotics with the right microorganisms for a given animal is probably very low,” Pellegrini said. “It is therefore difficult to comprehend how one specific product would be appropriate for all horses.” Not enough is known about the benefits of probiotics to make a definitive ruling either way, said Martin O. Furr, DVM, Ph.D., Dipl. ACVIM. “At present it is unclear if this is an overall good thing or a waste of money,” said Dr. Furr, a professor and Adelaide C. Riggs Chair in equine medicine at Virginia Tech’s Marion duPont Scott Equine Medical Center. “There is some evidence that at least some of the products are helpful, while others are not. More research needs to be done to fully understand their benefits and appropriate uses.” It’s important to note that there are many probiotics and they are not all equivalent, he added. “Some have been shown in various species to have good effects, while others have not—they are not all created equal.” Furr said some probiotics may help with immune response to parasites, or may help mediate the severity of diarrhea caused by specific agents. “The saccharomyces and pediococcus products probably have benefit in diarrhea caused by C difficile, and maybe some other agents,” he said. “Other probiotics—lactobacillus products—have no demonstrated effects.” A Caveat While Harman uses probiotics, she warned that there’s a major hurdle for practitioners or horse owners using them. “Most are not heat or oxygen stable. Consequently by the time you open the product there may be little left of the probiotics that were put in it at manufacturing,” she said. A few studies have looked into the amount of live culture versus what was claimed on the label, and few products had the amount of bacteria they claimed, Harman noted. “Many products, by the time you get them in the horse owner’s hands, have lost their efficacy,” Harman explained. That’s because many of the bacteria need to be in a temperature-controlled environment. Sometimes probiotics products are left for months at room temperature. And while they may not have passed their expiration date, the product may still be of little use depending on how it was stored and what kind of bacteria it contained, Harman said. “The concept of being able to successfully add probiotics to all different kinds of horse supplements is a fallacy by time horse owner buys it,” she said. The products may also be more or less effective depending on the region where they are stored and used. For example, in the Southern U.S. states, where Harman practices, the humidity tends to be high. That can be a factor in the survival of the bacteria in probiotics, Harman said. In other regions, one can often find horse country in rural areas where temperatures tend to be higher, which is another factor that can contribute to the life or death of the bacteria, Harman said. One pointer she offered for probiotics users is to be sure that products sold are tested to see if the product still contains the advertised amount of live bacteria. “I use companies whose products I know contain active probiotics at the time the customer receives it,” she said. “I research my companies and that’s the key,” Harman said. “Users need to know the companies are using top quality, uncontaminated sources that have gone through independent lab testing or internal lab testing to assure there are still active cultures by the time the expiration date comes around.” Future Of Probiotics With more horse owners becoming conscious of the value of good digestive health of their animals, the demand for probiotics may be even greater in the future, Harman predicted. She believes the most exciting research in the area is being done in the human medicine world, which she believes will eventually trickle down into the veterinary world. Efforts to map the human biome are the next step, in Harman’s estimation. And she’s encouraged by scientists who are looking at the presence of bacteria at all stages of growth —in the uterus, at birth, during youth and into adulthood. “They’re not ready yet to say from the research that we should be giving probiotics to everybody, but probably in a few years we’ll be able to take stool sample or sample of skin and tell what probiotics you should take,” Harman said. “I’m sure the veterinary researchers should catch on to that. “Through scientific learning of what the effects of probiotics are on these systems, manufacturers will eventually be able to more sensibly produce probiotic supplements, instead of throwing probiotics into substances and hoping the horse gets some.”
