Page 66 - December 2017

Careful caregiver monitoring is the key to successful management of foal diarrhea.
Keith chaffin, dVM
susan eades, dVM, Phd
equine Initiative website: tamuequine.com
cVM website: vetmed.tamu.edu
FIntroductIon
oal diarrhea is a significant problem of grow- ing foals, ranging in severity from self-limiting to death. Appropriate monitoring of foal health
throughout the suckling period is critical so that therapeutic intervention is initiated early in the illness to reduce the severity of consequences.
to seek veterinary treatment can reduce foal survival. Severe dehydration and shock can develop very quickly in foals with infectious diarrhea, making veterinary assessment an emergency to avert severe ill- ness or death. A complete blood count and chemistry will help the veterinarian assess the severity of the illness and develop an appropriate plan for fluid and electrolyte replacement therapy.
causes and dIagnosIs
Rotavirus, Salmonella sp., Clostridium dif-
ficile and perfringens, Lawsonia intracellularis, Rhodococcus equi, and parasites (e. g. small strongyles, Parascaris equorum, Strongyloides) are
the common infectious causes of foal diarrhea. Enterococcus durans, Coronavirus, Bacteroides fragilis, and Escherichia coli are bacteria and viruses that less commonly cause foal diarrhea. Rotavirus
is a viral disease that most frequently affects foals
a few days to 2 months of age and often afflicts multiple foals on a farm. The virus spreads com- monly from the feces of older foals and mares that may have milder diarrhea or no clinical signs. Feces can be submitted to the laboratory to identify the virus in the feces. Salmonella and Clostridium are bacteria that can cause severe diarrhea with dam-
age to the intestinal wall. Salmonella is detected by culture or molecular testing (PCR) of fecal samples. Clostridial infection (difficile or perfringens) is detected by testing the feces for the toxins (ELISA
or PCR) produced by these bacteria. Other bacteria are also diagnosed by culture or PCR. Parasitism is most often detected by fecal testing for ova (eggs); however, parasites can sometimes cause sufficient intestinal damage to lead to diarrhea before ova are produced by the adult parasites, in which case fecal testing may provide false-negative results. Lawsonia intracellularis is a bacterial infection in older suckling and weanling foals that causes a syndrome known as equine proliferative enteropathy (EPE). Clinical signs include weight loss, diarrhea, protein loss, and fluid swelling (edema) in the legs and ventral abdomen and thorax. This condition can be difficult to diagnose,
as blood tests indicate exposure to the organisms but do not necessarily confirm infection. Fecal testing (PCR) for the organism can sometimes be negative
in animals with the disease. In addition to fluid and electrolyte therapy, foals with EPE require specific antimicrobial treatment and may need plasma therapy to restore blood protein concentrations, so veterinary
Dealing with Foal Diarrhea
Story by Keith Chaffin DVM, Diplomate ACVIM Large Animal and Susan Eades, DVM, PhD, Diplomate ACVIM Large Animal, Department of Large Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843
Diarrhea is an inevitable event in the life of neo- nates of all species. When diarrhea occurs in the first 7-10 days of a foal’s life, it is often called foal heat diarrhea. This physiologic diarrhea may not be caused directly by the mare’s foal heat cycle, but may result from changes in intestinal microbial flora during nor- mal intestinal development. During periods of rapid growth, milk consumption (and other feedstuffs) increases and may result in bacterial fermentation into osmotic products, causing nutritional diarrhea. Foals with foal heat and nutritional diarrhea have loose stool with no other symptoms of illness. Body temperature, appetite, strength, and activity levels
are all normal in foals with foal heat and nutritional diarrhea, and the diarrhea is self-limiting (lasting 1-2 days at the most). Foals that are only a few weeks of age should suckle frequently (at least hourly) and thus will likely nurse each time their caregiver comes to observe their behavior. Foals with abnormal nurs-
ing behavior (for example, decreased frequency of nursing) or abnormal activity (for example, weakness or lethargy) should be examined for an infectious cause of diarrhea. Rectal temperature should be taken at the onset of diarrhea and twice daily until the diarrhea resolves. The volume and frequency of the diarrhea should also be monitored, which requires frequent observation of the foal. Fecal staining of the perineum (Figure 1) is commonly used as evidence
of diarrhea in foals, but does not allow the severity
of the diarrhea to be determined. Foals that are less than one week of age, with
abnormal nursing behavior,
diarrhea of greater than 2
days duration, weakness
and decreased activ-
ity, body temperature
above 101.5 degrees F, or
watery diarrhea occurring
frequently (more than 6-8
times per day), should be
examined by a veterinar-
ian. Waiting until a foal
completely stops nursing
Figure 1
64 SPEEDHORSE, December 2017
Fecal staining of the perineum in a foal with diarrhea.
veterinary views
Keith Chaffin