- Definition
- Pathophysiology
- Systems Affected
- Genetics
- Incidence/Prevalence
- Geographic Distribution
- Signalment
- Signs
- Causes
- Risk Factors
BASICS
- Diarrhea results in loss of water and electrolytes due to increased secretion, reduced absorption, increased luminal osmolality, and altered GI transit time. Loss of disaccharidase activity (lactase) secondary to destruction of enterocytes causes maldigestion of milk sugars and subsequent osmotic diarrhea
- Bacterial toxins can cause intestinal inflammation, leading to maldigestion and malabsorption
- Small intestinal disease (enteritis), colonic disease (colitis), or a combination of both can cause diarrhea in foals
- Loss of large volumes of electrolyte-rich fluid can lead to electrolyte, fluid, and acid–base derangements
- Loss of enteric barrier function can allow absorption of enteric toxins or translocation of enteric bacteria with subsequent septicemia and multiple organ dysfunction
- Intestinal ischemia or hypoxia from hypoperfusion or acute anemia can initially result in noninfectious diarrhea that could lead to septicemia due to bacterial translocation from a breach of the intestinal barrier
- GI—as described earlier
- Cardiovascular—hypovolemic shock and tissue hypoperfusion; toxemia, inflammatory cytokines, electrolyte derangements, and ischemia can lead to myocardial dysfunction
- Renal—hypovolemia, reduced renal perfusion, and toxemia can cause prerenal or renal azotemia, and subsequent renal injury
- Nervous—electrolyte derangements (e.g. hyponatremia) and hypoglycemia could lead to neurologic signs, including depression and seizures; meningitis from bacterial (e.g. Salmonella spp., Escherichia coli) translocation
- Common disease of foals
- 25% of foals 0–7 days of age, 40% at 8–31 days of age, and 8% at 32–180 days of age have diarrhea at some point
- Case fatality rate is low (~3%)
Sepsis-related diarrhea is most often seen in foals <2 weeks of age. Diarrhea due to viral infection or other causes is most commonly seen in foals <1 month of age.
- Often acute onset but can become chronic. Some foals have mild diarrhea but are otherwise well
- More than 1 foal may be affected
- Determine dietary history, deworming history, history of diarrhea in neonatal foals, housing and management practices, medications administered, pregnancy history including premature lactation
- Early on foals are bright, alert, and responsive with normal vital signs. Depending on the etiologic agent, disease can progress rapidly to dehydration, hypovolemia, depression, and recumbency
- Consistency of diarrhea can vary from pasty to watery, and color of feces can vary from yellow to red/bloody
- Severely ill foals may show signs of colic, abdominal distention, and/or tenesmus, often before onset of diarrhea
- Rectal temperature can be normal, low, or high. Cold extremities and hypothermia are consistent with severe disease. Entropion may develop in severely dehydrated foals
- Signs of hypovolemia include depression, tachycardia, weak peripheral pulse, and cold extremities
Infectious and Parasitic Causes
- Most foals with diarrhea do not have a definitive diagnosis. Rule out infectious disease when there is more than 1 foal at risk
- Bacterial—e.g. Salmonella spp., other Gram-negative sepsis/endotoxemia, Clostridium (difficile, perfringens type C), Rhodococcus equi (usually >3 weeks of age)
- Viral—common: rotavirus; rare: adenovirus, coronavirus
- Protozoal—e.g. Cryptosporidium spp.
- Parasitic—e.g. Strongyloides westeri and Parascaris equorum
- Mare—short or prolonged gestation, placental disorders, dystocia, maternal diseases
- Foal—failure of transfer of passive immunity, prematurity/dysmaturity, neonatal maladjustment syndrome, hypoxia (isoerythrolysis, pneumonia)
- Environment—poor farm management, inadequate hygiene, presence of pathogenic organisms
DIAGNOSIS
TREATMENT
MEDICATIONS
FOLLOW-UP
MISCELLANEOUS