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spot is anything less than 400mg/dl. There are of the foal. Yet, any occurrence of diarrhea in a
various methods to test the IgG of a foal, most of which are available in a stall-side test kit. Qualitative tests, such as the popular SNAP test, provide a range of IgG levels, and is essentially
a “yes or no” style of test. Quantitative tests provide an exact measured number of the IgG level. It is the protocol of our farm to check
not only the IgG level, but also to perform a complete blood count and to measure fibrinogen. The CBC and fibrinogen both can serve as early indicators of impending trouble even if the IgG is adequate, and treatment can be implemented prophylactically before the foal begins showing clinical symptoms.
Treatment of failure of passive transfer depends on the age of the foal, severity of
the FPT, and overall health status of the foal (determined by clinical exam and ancillary blood tests). Antibodies from colostrum are absorbed through the foal’s digestive tract until about 18 hours of age. Thus, if FPT is diagnosed prior
to this 18-hour mark, oral intervention can be undertaken to correct a low IgG level. Typically, the foal will need to be fed via a nasogastric
tube and can be provided colostrum from the dam, if it has been measured and deemed to
be of acceptable quality, or banked colostrum (colostrum previously obtained from another mare and frozen) can be used. It is important
to remember that administering ANY oral substances other than colostrum to a neonatal foal will expedite the “closure” of their gut and interfere with the normal antibody absorption.
FPT diagnosed later than 18 hours of age, or if it is associated with concurrent illness or severely low IgG levels, requires more aggressive treatment. High IgG plasma administered intravenously
is the treatment of choice, with prophylactic antibiotics and other supportive care measures implemented as necessary. Depending on the severity of the FPT, multiple plasma transfusions may be required, as will frequent monitoring of the IgG and other blood values of the foal.
NEONATAL DIARRHEA
Foal heat diarrhea is a common term for
a non-infectious, typically benign cause of diarrhea that most every foal will experience around 5-14 days of age. It is so called because
it often coincides with the mare’s first heat cycle post foaling. The fact that the mare is in heat, however, does not have anything to do with
the actual cause of diarrhea. The exact cause is not known, but it is believed to be due to the turnover of the cells that line the GI tract of the foal. This cause of diarrhea is often mild and self- limiting with no change in attitude or appetite
foal warrants evaluation by a veterinarian chiefly because the infectious causes can strike rapidly and severely. Diarrhea can be the presenting complaint of foals with sepsis, and sepsis should be the primary differential diagnosis until it can be ruled out.
Infectious neonatal diarrhea can be attributed to a number of infectious agents with varied degrees of severity and symptoms; yet treatment
is predominantly symptomatic and in an effort to combat dehydration. Neonates with an infectious cause of diarrhea can go from fine, frolicking foals to dish-rag limp, severely dehydrated, and in grave danger in a matter of hours. Thus, any incidence of diarrhea in a neonate should be taken seriously. Common etiologic agents include Rotavirus
and the bacterial culprits Clostridium perfringens, Clostridium difficile, and Salmonella.
Rotavirus is commonly encountered in foals housed in large groups and can infect foals from
2 days to 2 months of age. They often display symptoms of dehydration, decreased appetite,
and profuse watery diarrhea. The virus infects and affects the microvilli in the GI tract and creates
a situation of increased secretion and decreased fluid absorption from the gut. As with any virus, there is no specific treatment, but these foals tend to respond well to IV fluid administration and oral sucralfate to coat and soothe their GI tract. There is a vaccine available that can be given to the mare during her pregnancy which is helpful in preventing rotavirus in the foal. Broad spectrum antibiotics are often implemented to prevent secondary bacterial infections and IV plasma administration can be a benefit to critically ill foals. Studies have shown that 40% of foals with diarrhea worldwide will have Rotavirus isolated from their feces.
The Clostridial causes of diarrhea (C. perfringens, C. difficile) are increasingly recognized as a serious pathogen in foals.
Foals with clostridial diarrhea often display abdominal pain along with dehydration
and watery diarrhea. They may even have frank blood in their feces, which has been associated with a poorer prognosis. Finding this pathogen along with the associated
toxins in feces is definitive. Treatment for Clostridium diarrhea is symptomatic with
the addition of the antibiotic Metronidazole. Broad spectrum antibiotics are often used in conjunction with Metronidazole to prevent bacterial translocation-associated sepsis in these foals. It is also possible to vaccinate the mare during pregnancy as an avenue to help prevent clostridial diarrhea once the foal is born.
Other bacterial causes of diarrhea have been implicated such as Salmonella which is
High IgG plasma administered intravenously is the treatment of choice for failure of passive transfer (FPT), with prophylactic antibiotics and other supportive care measures implemented as necessary.
typically associated with septicemia in foals and E. coli (which has not been fully described). It
is important to remember that 50% of foals presenting with diarrhea from ANY cause will be bacteremic at the time of their first exam.
Another common cause of foal diarrhea
is the parasite Strongyloides westeri. Foals are infected via milk and tend to display symptoms of diarrhea around 8-12 days of life. Fortunately, this cause of diarrhea is often mild and responds well to deworming of the foal. A common husbandry practice is to deworm the mare with Ivermectin after foaling to halt the parasite before the foal can ingest it from the mammary gland.
© Megan Petty
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