Page 95 - March 2020
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                 INFECTIOUS CAUSES
Bacterial pathogens include E. coli, Salmonella, Clostridium perfringens, C. dif- ficile. The most common virus is rotavirus. “Many breeding farms vaccinate pregnant mares for rotavirus in the 8th, 9th, and 10th month of pregnancy to help boost the antibod- ies in colostrum,” says Martinez.
“Rotovirus can be a significant problem on large breeding farms due to extensive animal traffic, and can be endemic in the environ- ment,” says Schroeder. “Rotovirus can cause classic diarrhea outbreaks. It can be a challenge because this virus is aerosolized and can be spread not just by the fecal-oral route, but also through the air – potentially exposing all foals. Older foals can act as a reservoir population and infect younger foals,” he explains.
Dr. Bonnie Barr of Rood and Riddle in Lexington, Kentucky, says sometimes corona virus is seen. “We don’t know yet how much corona virus actually affects the younger foals. It may be there and we discover it with molecu- lar testing such as PCR. It may play a role, but may not be the key player,” says Barr.
Cryptosporidium is a protozoal intestinal parasite that can also cause diarrhea in young animals. “Those cases are possibly a bit immu- nocompromised. A strong, healthy foal may not become infected as easily,” she says.
“There are some other random, rare patho- gens you might see if you are doing a diagnostic fecal panel on a sick neonate,” says Martinez. “If a farm has a big outbreak, the veterinarian might do tests to try to pinpoint the cause.” An accurate diagnosis can be helpful to make sure the foals are on the right medications to deal with the pathogen.
Any wetness on the foal’s tail or on the buttocks, even if you do not see diarrhea, is a sign of trouble.
  Rotovirus, which can be a challenge because this virus is aerosolized – it can spread not just by the fecal-oral route, but also through the air, potentially exposing all foals
Martinez says some types of diarrhea are not infectious, such as the loose feces people refer to as foal heat diarrhea or milk scours. “This is when you might get by with just some probiotic support and sucralfate or anti-diar- rhea paste to coat and sooth the gut lining,” Martinez says.
These cases won’t need antibiotics, but should be monitored to make sure they don’t get worse. The foal is essentially healthy and keeps nursing. Be prepared to give supportive treatment if necessary and keep the foal’s messy hind end greased to protect the delicate skin from being scalded/burned by the acidic feces and taking all the hair off. Mineral oil or petro- leum jelly applied a couple times a day can help protect his tender skin from the irritation of being covered with diarrhea. Wash his buttocks gently before applying the soothing coating. This treatment will make him more comfort- able and prevent hair loss.
If the foal has watery feces for several days, a little Pepto Bismol (about 30 to 40 cc, which is about two tablespoons) can be given orally by syringe. Stick the syringe, without needle, into the back of his mouth and gently squirt the Pepto Bismol in a little at a time as he swallows it. This will soothe his gut and help slow the diarrhea, making him more comfortable. This type of diarrhea won’t need antibiotic treat- ment unless complications develop.
There are also a few other non-infectious causes of scours. “A hypoxic insult (lack of oxy- gen) to the gut can also cause diarrhea,” says Barr. “A hypoxic insult can occur secondary to prolonged dystocia, placental problems as the foal is being born, or the need for resuscita- tion at birth, and often other body systems
are affected. Treatment for the gut problem
Cryptosporidium, which is a protozoal intestinal parasite, can affect foals that may be a bit immunocompromised. Strong, healthy foals
are not as easily infected.
includes supportive treatment and giving the gut time to heal and normalize, which might mean withholding milk temporarily (and pro- viding nutrition intravenously).”
An orphan foal on milk replacer may also get diarrhea or indigestion. “If you have a foal on milk replacer, stick with the same brand and don’t keep changing. If you have to change, make the transition gradually,” says Barr.
“We can usually do some diagnostic test- ing to determine the cause, but we can’t just test a fecal sample because it would grow
many pathogens that may not be important,” Schroeder explains. For instance, there are many different types of clostridia commonly found in the environment and in the horse’s GI tract; their presence in a fecal sample may not mean anything. Testing for specific toxins can be helpful.
Diagnosis is often challenging in the sick
foal and requires time for results. This creates a debate regarding withholding therapy to test the foal first (having to wait for the results) and more debate in terms of the best test and test media to use. “Proper fecal sample collection and handling instructions can usually be obtained from the submission laboratory,” says Schroeder.
It is important to figure out why the foal is sick – not only for this particular foal, but also to know if it is contagious to other foals and to people. “It can be catastrophic if one foal with diarrhea serves as a source of infection for the others,” he says.
For diagnosis, everything starts with the basics – a physical examination of the foal and the mare and a thorough medical history. “We want to know what’s going on in the envi- ronment, whether the mare was sick prior to
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