BY HEATHER SMITH THOMAS

Intestinal infections can be deadly for young foals, especially in the first days and weeks of life. A clean environment, good care and monitoring, and being proactive to head off or deal with any problems are very important.

Dr. Gemma Cock, an internal medicine specialist at Peterson Smith Equine Hospital in Ocala, Florida treats many foals each year.

“I did my residency at the University of Florida and have been here at Peterson Smith since September 2024. The internal medicine specialists deal with the majority of the sick foals that come through here, so this is one of my main roles,” Cock said.

There are many different causes of foal diarrhea and one of the things breeders need to know is how quickly this can become severe.

“Profuse, watery diarrhea in a foal is a medical emergency,” Cock said. “They are much more fragile than an adult horse and become sicker a lot faster. They dehydrate very quickly because they have very little body mass and no reserves.”

Something like foal heat diarrhea is normal; those foals generally just have pasty or runny feces and are still bright and alert, still nursing the mare and are not really sick.  

“Foal heat diarrhea generally occurs at about two weeks of age or a bit sooner, but it shouldn’t occur at just a couple days old. Diarrhea at that very young age is serious because it can become worse very quickly,” Cock said.

“Any time a foal has watery diarrhea, however, this is a true emergency. Also, a lot of the things that can cause diarrhea are contagious and it’s important to use good biosecurity measures when dealing with sick foals. This involves cleaning, wearing gloves, etc. to help keep the disease from spreading through a foal population. If you have a large breeding facility, you will always have some with diarrhea so you need to try to isolate them so they are not sharing paddocks, etc. You need to be able to stop disease spread through the farm,” Cock said.

Breeders may want separate handlers for the sick foals and use separate utensils, tools and equipment for that stall. One may want to corridor off a section of the barn so a foal or foals can be isolated or move the foal to a different barn if available. Or simply keep the sick foals at one end of the barn and the healthy foals at the other.

Be careful when handling the manure and old bedding from that stall. If a foal has diarrhea, many of the pathogens are shed in the feces and the fecal-oral route is how the next foal may get the infection. The pathogens may shed from the manure off a person’s boots, gloves or hands when handling or assisting with the delivery of the next foal.

 

 

CAUSES – “The main causes of diarrhea in young foals are Clostridia, especially Clostridium perfringens, or C. difficile,” Cock said. “We also see rotavirus, including rotavirus A and rotavirus B, and Salmonella and sometimes E.coli. Sepsis, in general [from any cause] can also cause diarrhea in babies. The more contagious causes of diarrhea include Clostridia, salmonella and rotavirus. There are certainly some other pathogens that can also cause diarrhea but those are the most important and common ones we see.

“The best way to diagnose the cause is with a fecal sample for your vet to send for testing. If it’s a serious diarrhea it’s good to know what you are dealing with, in order for your vet to select the correct treatment.”

There are a few things that can cause diarrhea besides gut infections. Anything that irritates the digestive tract may cause loose feces. If an orphan is being fed milk replacer, this can cause diarrhea. It’s always important to determine the cause.

 

SIGNS – The foal will be dull, lying around more than usual, and off feed. Often the first clue will be that the foal is not nursing; the mare will have a full udder and is worried about her baby, or might be streaming milk.

“If you see a foal that has milk on its face, this means it has probably just been standing at the udder looking like it is nursing, but not actually nursing. The foal bumps the udder and the milk streams. Thus if the mare is streaming milk or the foal has milk on its face, this is not normal,” Cock said.

It’s important to keep close watch on young foals.

“Some of the things to look for are signs of dehydration,” Cock said. “The eyes will look sunken, the mucous membranes become dry and tacky, and these foals urinate less or just posture like they are urinating without passing urine. The eyes are often the big clue that can tip you off, to know that the foal needs fluids. Unlike adult horses, foals at this age are not drinking water and only have milk. If they are not nursing, they can become very dehydrated, very quickly.”

 

TREATMENT – If the foal is not nursing and is severely dehydrated, it will be necessary to administer intravenous fluids.

“Depending on the degree of hydration, there may be part of the small intestine involved as well, like an enteritis, or also the colon [colitis]. The foal may need to be held off milk because the GI tract is so sensitive. In that situation you must provide IV fluids because the GI tract can’t absorb oral fluids. Unlike adults that you can tube with water and electrolytes, the foal can’t tolerate water at that age. Milk includes nutrition, which can upset the GI tract even more.”

If the foal ends up in the hospital for treatment, nursing will be restricted. Since you need to keep the foal with mama (less stress to both of them if they can be together) you may need to muzzle the foal and milk out the mare. The foal can be on IV fluids with a little dextrose for nutrition, to let the gut lining start to heal. “The mare will be milked every 2 to 3 hours,” says Cock. Otherwise she will be miserably uncomfortable and you also don’t want her to get mastitis.

Treatment for the foal will depend on what is causing the diarrhea. Antibiotics are often needed in foals with diarrhea. The actual antibiotic your veterinarian might prescribe will depend on the pathogen, and even if the original cause was viral, this can lower the foal’s defenses and enable opportunistic bacteria to proliferate in the gut. It is important to work with your veterinarian regarding treatment.

“Foals are also more susceptible to bacteria in their blood when sick, even with diarrhea, making them higher risk for septic joint and umbilical infections so broad spectrum antimicrobial coverage is important with this young age group,” she says.

“Fluids to combat dehydration, withholding nursing for a short time, using gastro-protectants, etc. can be helpful,” says Cock. “These can be given orally or IV, depending on the severity of the diarrhea. We have several oral and IV options. Foals can be tubed with milk at home for hydration, or be given IV fluids in the hospital.”

A lot of people use probiotic pastes and other products that may help. There are also things that may help soothe and slow the gut. Products like Bio-sponge ® or Metamucil or other fiber-based products can provide a little more structure to the feces and help dry up the diarrhea. “You just have to be careful not to give too much or it may work in the opposite direction and cause constipation,” she says.

Every case is a little bit different. It also depends on whether the foal is three days old or three or four weeks old; the older foal may be a little easier to treat and not such an emergency. “It is crucial to treat any foal with diarrhea, however, because they can end up with bacteremia (bacteria in the bloodstream). This can put them at risk for septic joints and possibly end up with permanent damage to those joints.” These horses may not be sound later—and you definitely want an equine athlete to be sound. There can be serious consequences if the infection is not treated quickly.

Return to the April 8 issue of Wire to Wire