Page 56 - New Mexico Horse Breeders 2019 Stallion Register

Diarrhea in
Young Foals
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.
Ernest H. Martinez II, DVM, Hagyard Equine Medical Institute, says newborn foals (first 24 hours through the first week of life) are most at risk so it is crucial to quickly and aggres- sively deal with any diarrhea at this age, prefer- ably by experienced personnel or a veterinarian. “Those foals can get really sick, very fast. They dehydrate quickly and their electrolytes can get out of whack. The damage that can be done
to the GI tract from an infection can cause a bacteremia (bacteria in the bloodstream) or sep- ticemia, which can quickly be fatal,” he explains. These young foals have a naïve immune system and the infection may end up in the joints, with more complications later.
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 or might be streaming milk. “At this young age, these foals can go downhill very quickly,” says Martinez. Thus it is important to identify a problem quickly.
CAUSES
“Some of the bacterial pathogens we see
in young foals include E. Coli, Salmonella, Clostridium perfringens, C. Difficile. The most common virus we see is rotavirus, and most breeding farms vaccinate their pregnant mares for rotavirus in the 8th, 9th, and 10th month of pregnancy to help boost antibodies in colostrum,” says Martinez.
“Those are the main pathogens we see in young foals, though there are some other ran- dom, rare ones you might see if you are doing
a diagnostic fecal panel on a sick neonate. If a farm has a big outbreak, the veterinarian might do these tests to try to pinpoint the cause,” he explains. An accurate diagnosis can be helpful to make sure the foals are on the right medica- tions to deal with the pathogen.
There are some types of diarrhea that are not infectious, such as the loose feces that people refer to as foal heat diarrhea or milk scours.
“Research has shown that the loose feces at this time is not so much caused by the mare being in heat, but because the foal’s GI tract is changing and transitioning its natural flora. The diarrhea is not from anything different in the milk, but from changes in the gut. This is when you might get by with just some probiotic support and some sucralfate or anti-diarrhea paste to coat and sooth the gut lining.” These cases won’t need antibiotics, but should be monitored to make sure they don’t get worse.
TREATMENT
Because of the risk for septicemia in an infec- tious diarrhea, it’s crucial to get a sick foal on broad-spectrum antibiotics (gram-positive and gram-negative) and also metronidazole to deal with anaerobic bacteria like Clostridia. “Many of these antibiotics are administered by IV with a catheter, but some may be oral,” says Martinez.
“We try to identify the pathogen and do a sensitivity test to make sure we are using the right antibiotics, and this typically involves leaning a little toward the gram-negative side of the spectrum. The typical IV antibiotics might be Naxel and amikacin, or ampicillin and amikacin, etc. We try to use antibiotics judiciously and reserve some of them for use in the hospital,” he says.
“If it’s a virus, there’s not much we can
do to treat it other than supportive care, and broad-spectrum antibiotics to head off second- ary invaders and protect against bacterial trans- location through the gut wall,” he explains.
Fluid therapy is also crucial to keep the foal from becoming too dehydrated. “If the diar- rhea is severe or the foal is not nursing at all, fluid therapy is very important. In the young foal, we have to be proactive and aggressive.
If the foal has a fever, we can use anti-inflam- matory/anti-fever medications like Banamine, Ketophen, Dipyrone or Equioxx but we must use these carefully in young foals; we don’t want to cause gastric ulcers.”
The medication may help bring the fever down and the foal may start feeling better, and may have more interest in suckling. “This can be good and bad; you have to make sure the com- promised GI tract has good motility and can
handle the milk. Sometimes you are better off to muzzle the foal and milk out the mare, and put the foal on IV fluids with a little bit of dextrose for nutrition, and let the gut lining start to heal. This helps everything move out and clear out, rather than having food irritate the damaged gut lining, taking longer to heal,” he explains.
“Then when you take the muzzle off and
let the foal nurse again, make sure he doesn’t nurse too much at once and gorge himself.
He may not be able to go back to nursing full time; you might want to let him suckle for only 2 minutes every hour to see how he handles
it. You don’t want the foal to get colicky and uncomfortable. A sick foal with an inflamed GI tract needs supervised, monitored nursing or you may have to deal with colic,” he says. Make a gradual transition and if the foal can’t tolerate milk, he may need to be muzzled again for a while, and fed intravenously a little longer while the GI tract heals, and then slowly rein- troduce milk again.
“Another simple treatment if the foal is not nursing or has a little diarrhea, is to put him on lactaid, which you can buy at the grocery store. The lactase helps break down the milk sugars and make them easier to digest,” says Martinez.
Anti-diarrheal medications are also used, and these include a number of binders or pastes to help slow and firm up the diarrhea. “These include Pepto-Bismol, various types
of binding clays like our Relieve Paste, also known as Hagyard diarrhea paste, and other anti-diarrheal compounds that bind toxins and hopefully firm up the feces,” he says.
The foal should also receive anti-ulcer therapy. “Some of these medications include sucralfate, Gastrogard, ranitidine tablets, and other proton-pump inhibitors or things that coat the mucosa of the stomach. The main sign of ulcers in foals is grinding of the teeth, which signals discomfort. You want to be proactive if the foal might have ulcers, because you don’t want them to get worse, to the point of perfora- tion,” he says.
Sick foals are at risk for ulcers because they are not feeling well and their GI tract might not be functioning normally due to the diar- rhea. “With very young, newborn foals there
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