Young foals are vulnerable to many diseases that cause diarrhea. Risks will vary, depending on geographic region and the environment on each individual farm (and level of contamination) where foals are born. One of the most serious GI tract infections is caused by certain species and types of Clostridium. These are hardy spore-forming bacteria that are often present in the environment. Some of these species cause other diseases like tetanus, botulism, black disease, malignant edema and blackleg. There are effective vaccines for protecting calves, lambs and goat kids against Clostridium perfringens, which causes severe GI tract infections in these species, but no vaccines have yet been licensed for use in horses. Treatment and prevention strategies for foals have been extrapolated from methods used in other livestock, on a trial and error basis.
Paul Zancanella, DVM, of Rock Springs, Wyoming, says the most important thing for horse owners in dealing with these infections in foals is early detection. “When we see diarrhea in foals we think it’s important to get the veterinarian involved as soon as possible so he/she can see the early signs, which can help in diagnosis. Sometimes diarrhea in foals is hard to diagnose because it may be caused by viruses or bacteria. Often the Clostridium infection is not accurately diagnosed until we have some post-mortem cultures of intestinal feces,” he says.
TREATMENT - “Any time a foal gets diarrhea it’s important to devise a good treatment plan that includes antibiotics and IV fluids. Usually we use conservative doses of Banamine, as well—to ease the gut pain and reduce the inflammation,” he explains.
“We find that in severe cases we have to withhold milk from the foal and keep him from nursing for about 24 hours and sometimes longer. This seems to slow down the multiplication of bacteria within the gut and also allows better concentration of the oral antibiotics in the gut. It seems like the milk acts as a culture—a food for the Clostridium bacteria to thrive on. Taking the foals off the mares for 24 hours, if they have severe diarrhea, is one of the best things you can do as an adjunct to treatment,” he explains.
Scott Toppin, DVM (Littleton Equine Medical Center in Littleton, Colorado) says the disease often seems to affect strong, vigorous foals from mares that are lactating well. These foals are consuming a lot of milk, and this may be a factor in the GI tract environment that makes it more able to support swift multiplication of the toxin-forming bacteria. “When the foal has a lot of milk in the gut, it creates an environment in which these bacteria can grow,” says Toppin. If a foal continues to drink milk, the bacteria continue to multiply and produce toxins and gas. These foals tend to colic and/or bloat up after nursing, so it’s best to withhold milk until the foal starts to improve.
Josie Traub-Dargatz, DVM (Professor, Colorado State University) says that in her experience the foals with bloody diarrhea don’t digest milk very well, and colic if they keep nursing. Putting them on IV nutrition reduces the incidence of recurrent colic. “We haven’t had to do this aggressive therapy for prolonged periods, nor on all foals with this disease. Keeping the foal off milk for 2 to 3 days is usually enough. By then the foal’s clinical signs have resolved and we can gradually reintroduce oral milk intake,” she says. “When we can keep foals from suckling the mare for a day or two, the vicious cycle of colic after suckling seems to resolve.”
You don’t always know what you’re dealing with when a foal gets sick. Even though diagnostic tests can be done from a fecal sample, it may take a couple days to get results back. “Rather than wait to find out, we generally start treating the foal very quickly and very aggressively, because if we wait for the results it may be too late,” says Toppin.
There are several antibiotics that can be used, but most veterinarians prefer either metronidazole or penicillin. “I generally use potassium penicillin IV in these foals,” says Zancanella. “Some foals we also give Gentamycin to take care of secondary invaders. Penicillin is one of the more effective antibiotics against Clostridium. We usually add potassium penicillin to the IV fluids we’re giving. We give it as a continuous infusion, adding 20 million units to a 5 liter bag of fluid, and administer it at approximately 30 drips per minute,” says Zancanella.
Foals can be treated intensively at an equine hospital or at the farm, depending on facilities available. “You need a good box stall. Most veterinarians who have a box stall at their clinic have an IV set up for horses suspended over the stall to hang those bags on. The foal is able to move around and not get tangled up in the IV line,” he says. “We install a catheter in the foal. If you’re going to give IV fluids to a foal, it’s important to put in a long-term catheter. We like to use a 3 or 5 inch catheter and suture it into the foal.” This helps make sure it won’t come loose.
The foal is either muzzled or paneled off from the mare so it can’t nurse. “We’ve done it both ways, but we prefer to have a panel between them. The mare is right there for comfort, but the foal can’t nurse. It’s important to milk the mare regularly to keep her comfortable. If she has a large, full udder it will be sore and she won’t want the foal to nurse when it’s time to reintroduce the foal to milk,” says Zancanella.
Some foals become severely sick so suddenly that they become dull and start to go into shock even before they show signs of diarrhea. “These can be hard to diagnose. A lot of those foals are colicky and you have to be sure it’s not due to something else like ulcers or other types of gastro-intestinal infections. Most GI tract infections are treated similarly, however. If a foal shows signs of colic, it’s important to get your veterinarian involved right away so there can be some diagnostic work, and pain management for the foal so he won’t complicate things by rolling and thrashing around. If he can be started early on treatment with antibiotics and fluid, this really helps,” he says.
“The earlier we treat these foals, the better luck we have with them. Fluid is very important since many of the antibiotics and anti-inflammatory drugs are relatively renal-toxic; if the foal becomes dehydrated these drugs can cause kidney damage. You need to have the foal on IV fluids so he won’t be dehydrated while you’re giving these types of drugs,” he explains. Extra fluid is also important to help prevent or reverse shock.
“There is some clinical evidence that cattle antitoxin (for Clostridium perfringens type C and D) given orally to foals diminishes the signs of the infection. This is an extra-label use for these products, however, since this treatment is not licensed for use in horses. But it may help bind the toxins. The Clostridium infections in foals that I have diagnosed have almost all been type C or D. I have seen Clostridium difficile a few times, but the vast majority have been Clostridium perfringens. From talking with other veterinarians I understand that this is not always true, but in our practice it has been the case,” says Zancanella. The cattle antitoxin product is sometimes used in foals as treatment or as a preventative against types C & D.
Use of Bio-Sponge (an oral product containing Di-Tri-octahedral Smectite, which absorbs and binds to the toxins) is also helpful in treatment. “I think it is fairly effective in binding toxins in the gut, so this could be given to the sick foal,” he says.
Toppin says it’s a bit like using charcoal in that it tends to absorb and bind to the toxins. “You must be careful on dosage, since it can also plug the tract. Bio-Sponge comes as a paste, in a tube for ease of oral administration. We usually use it for treatment rather than prevention, because of the risk for constipation if overdosed,” he explains.
Traub-Dargatz did some in-vitro studies to see how the product absorbed the various clostridial toxins, and in test tubes it appeared to bind the toxins produced by both C. perfringens and C. difficile. “One concern was that it might also bind the antibodies from colostrum, if you gave it to a foal immediately after birth. We did another in-vitro study that suggested it does bind colostral antibodies, but not to the degree that it binds the toxins. If people are thinking of using it as a preventative, they should wait until the foal has suckled several times, and give the product several hours after that—after the foal is at least 8 hours old,” she says. Dosage should be carefully calculated to avoid risks for constipation due to overdose.
PREVENTION – There are numerous ways to try to prevent these infections. Keeping foaling areas clean is a very important key. If mares are out in paddocks or pastures there is always some risk of exposure. Foals are curious and nibble soil. Mares may get dirty if there’s any manure where they lie down, and foals may pick up bacteria while nuzzling around the mare’s legs, belly, tail, etc. It’s difficult to completely eliminate exposure.
Since the most vulnerable time for foals seems to be the first week of life, it’s wise to be diligent in keeping their environment as clean as possible during that time. “Some farms have found that when mares are foaling on grassy pastures, away from the animal concentration areas, they reduce their problems,” says Traub-Dargatz. “One of the farms that had repeat occurrences each year had fewer problems after they stopped having mares foal in their calving shed. I don’t think we can totally prevent exposure if foals will be outdoors, but we can potentially reduce the level of exposure,” she says.
Meticulous attention to sanitation in the barn is a big factor. It pays to disinfect stalls between foalings. “It’s impossible to disinfect dirt floors, but we can clean the walls, clean out all soiled bedding, and try to let the floor dry between animals. We can remove the mare’s manure as she passes it, increasing the frequency with which we clean the stall from once a day to several times a day,” says Traub-Dargatz.
The spores are hardy and can withstand heat, cold and drying. “To get rid of them requires mechanical removal. Cleaning and washing are most effective. There are some disinfectants that will kill these spores, but most of the common disinfectants are ineffective. Work with your veterinarian to come up with a plan for cleaning, and use of a proper disinfectant,” she says. There are safety guidelines that must be followed to protect the people applying the disinfectant, and guidelines regarding when to allow animals access to the disinfected areas.
Bleach can inactivate the spores, but the bleach itself is inactivated if there’s any organic material present such as dirt, manure, straw or hay. Scrubbing stall walls with detergent and scrub brush can help remove any contaminants. A non-porous surface is easier to totally clean and disinfect than wood. Wood can be covered, if necessary, with a couple coats of slick-surface paint. If a particular area is a repeat problem (if foals born in a certain stall become sick), you might have to dig out that stall and remove the dirt floor, and consider a different flooring surface that would be easier to clean. Some people use stall mats that they take up and wash/disinfect between foalings, putting clean bedding on top of the mat.
Cleaning the mare’s udder and area below her vulva with warm soapy water (no disinfectants) then rinsing off the soapy water and gently patting dry with paper towels—when she goes into the foaling stall, and again right after the foal is born—will reduce the amount of bacteria the foal ingests when he seeks the udder to nurse. Mares normally pass manure during labor, and often while shedding the placenta, so the hindquarters and tail should be cleaned up afterward.
“It’s also important to try to avoid stress to the mare and foal,” says Toppin. “I know this is a hard thing to evaluate and achieve, but anything that might be stressful to mare and foal should be avoided if possible. I also feel that if you’re careful to avoid contamination, especially from one foal to another, this can really help. If you have a sick foal, don’t go back and forth between it and another foal or a pregnant mare. There are theories that maybe these mares are getting infected prior to pregnancy or foaling and are then passing the bacteria on to their foals.”
If the mare has some of these bacteria in her GI tract, they won’t affect her, but they may be present in her manure and the foal could pick them up when eating some of her manure (as young foals do). If the mare gets dirty, lying in manure, the foal may pick up bacteria when nuzzling her legs, belly or hindquarters.
Some mare owners resort to using the cattle vaccine in pregnant mares, in an effort to stimulate production of antibodies that would then be present in their colostrum to help protect their foals. “Even though this is not a licensed use of the vaccine, I feel there is some evidence that using the cattle vaccine containing Clostridium perfringens type C and D does prevent the disease. This is all clinical experience, however. I don’t think there are any research studies to show this. Since this vaccine is not labeled for horses, your veterinarian would need to prescribe it, and make sure the clients understand that this is not an approved use, and not without risk,” says Zancanella.
Toppin has used the vaccine on farms where foals have been lost to Clostridium in the past. “I have not seen a problem in the vaccinated mares in my practice, but there is always some risk. The manufacturer has not done studies in horses regarding safety and efficacy. This vaccine should only be used in horses if we feel it is really necessary,” explains Toppin. There have been instances in which mares developed abscesses at the site of vaccination, necessitating surgical drainage and treatment. This can be very debilitating in a late-pregnant mare.”
Clostridial enterotoxemia is a sporadic disease in foals, so it’s hard to determine, without a controlled study, how effective the cattle vaccine really is. A breeder might vaccinate all the mares one year, for instance, and have no cases of diarrhea in the foals, and feel that the vaccine worked as a prevention–when in reality there might not have been any cases that year, anyway. But numerous farms that have had problems with Clostridium infections in the past are now using the vaccine and feel that it’s been a help.
“I feel that in the face of severe outbreaks on certain farms that have had serious problems year after year, using the cattle products has been somewhat effective,” says Zancanella. “I’ve used the cattle vaccine with some of my clients and they tell me it works. This is purely subjective, and a hard thing to evaluate, but I’ve had clients tell me it has cut down their Clostridium problems by doing this.” This is an option people could try, if they’re having a lot of sick foals.
“There is also a possibility that an autogenous vaccine could be created. I have not investigated this myself, but someone with a really bad problem might talk to a company that produces hyperimmunized serum from mares. This could be an option, as well,” he says. This could be even more specific against the particular strain and type on a certain farm, and more effective than simply using the cattle vaccine.
Traub-Dargatz says there are serum (plasma) antitoxin products collected from horses that have been vaccinated with the toxoids.
“The idea would be to give these biological products to newborn foals to try to prevent this disease. However, there have not yet been any controlled studies regarding their efficacy and safety in newborn foals,” she explains. “Anyone considering using the vaccines or antitoxin products should work with their veterinarian and rely on his/her recommendations, in terms of experience with products that have appeared to be relatively safe and effective. I would not recommend using any of these without consultation with your veterinarian,” she says.
“If the disease is being caused by type A, we don’t have as many options, though there is now a type A toxoid for cattle—but it is not produced by as many companies as the types C and D toxoid. I do not know of anyone recommending the type A product for use in horses,” she says. If the farm is using type C toxoid and the disease is being caused by type A, it’s questionable that the vaccine would give much benefit.
Some farm owners who have lost foals now use antibiotics preventatively. Rather than wait until a foal gets sick, they give every foal an antibiotic for the first 3 to 5 days of life. One of the antibiotics effective against these bacteria is metronidazole (Flagyl), and it is often used orally in treating sick foals. Some breeders who’ve had a lot of problems with the disease have resorted to giving every foal oral doses of this antibiotic during the first days of life. “Using metronidazole as a preventative is probably a safe alternative to the vaccine, and probably has less side effects. Metronidazole is a fairly good broad-spectrum antibiotic that is effective against anaerobic organisms like Clostridium,” says Zancanella.
“There is some worry that bacteria will become resistant to the drug when used routinely in all foals as a preventative,” says Traub-Dargatz. “It’s important to weigh the risk versus benefits of this approach.” She also points out that if certain prevention methods are used and none of the foals get sick, we really don’t know whether it was the treatment or vaccine preventing the disease, or just a natural lack of disease that year.
None of these things—the vaccines, the Bio-Sponge, nor the antibiotic drug—have been used in controlled studies. “It’s difficult to set up a study because when people have had one or two foals die and then start to use one or more of these preventatives, they want to do it for all the foals. They don’t want to do it for every other foal born (leaving some unprotected, as controls),” says Traub-Dargatz.
Mare owners should discuss a preventative strategy with their veterinarians, especially if they’ve experienced this disease before in their foals. Often when this disease is encountered, more than one foal on the farm will get sick. “It’s important to quarantine and isolate any sick foals, because it is contagious,” says Toppin. The sick foal will pass high numbers of bacteria in the diarrhea.
“Even though these bacteria are already present in the environment, it makes sense to use good hygiene when working with a sick foal,” says Traub-Dargatz. “Don’t go in and out of that stall without cleaning your footwear or having specific footwear for that purpose. Cleaning your hands after handling the foal is also important. C. difficile can also affect humans. Washing with soap and water is important after handling the sick foal or cleaning the stall, even if disposable gloves have been worn,” she says.
If the foal has diarrhea, clean the tail and buttocks once or twice a day. The liquid fecal material can scald the skin, making the area sore and raw. “If the foal needs injections, people often put a needle into the buttocks, and if this area is soiled with diarrhea, bacteria may be carried into the muscle with the needle. This can result in more problems. If owners are giving injections into the muscle, they should talk with their veterinarian about how and where to give those,” she says.
