Foals can be extremely susceptible to infectious foal diarrhea; their immature immune systems put them at risk for contracting viral or bacterial diarrhea, or both. Being able to recognize and intervene can be the difference between a foal surviving infectious diarrhea or not.
There can be different pathogens at play in viral diarrhea in foals, however, the most commonly seen is rotavirus. Because rotaviruses are highly contagious they can easily spread to other foals in a facility. This makes it doubly difficult to control and isolate. Rotavirus typically has an incubation period of 3 – 10 days. During this time they will develop clinical signs such as a decreased appetite, mild-to-moderate fever, watery stools, and depression.
Other viral causes of diarrhea can include coronavirus but this is less commonly found than rotavirus.
Bacteria are found in various levels in the healthy gut. When one or another takes over, however, it can wreak havoc on a foal’s digestive and immune systems. Unlike a mostly singular viral cause, there are numerous causes of bacterial diarrhea in foals. Salmonella, clostridium, E. coli, and rhodococcus are most frequently found and, like viruses, can be highly contagious. Fecal smears and/or cultures are used to isolate which bacterium are present and in what numbers; foals are particularly susceptible to bacterial infection because of their immature immune systems.
Much like the symptoms that go with viral causes, foals present with runny or watery stools (consistency and color will vary depending on the specific bacterial culprit). In addition, they may develop hemorrhagic diarrhea, colic, tachypnea (abnormally rapid breathing), reduced appetite, lethargy or depression and dehydration.
Other Infectious Causes
While viral and bacterial disease are the most commonly seen causes of foal diarrhea, protozoans contribute to a fair number of foal diarrhea cases. Aeromonas hydrophila and Cryptosporidium parvum are two of the most frequently found. Others such as Giardia are also known to cause diarrhea in foals.
In the next foal diarrhea segment, we will delve deeper into the treatment and prevention of this potentially devastating condition.