Scours is a term that refers to diarrhea in livestock. It is more commonly used to describe diarrhea in young stock (calf scours, lamb scours, etc.). Foal scours represent one of the most significant medical problems of foals in terms of the number of cases, mortality rate, and costs.
There are many causes for diarrhea which affect the severity of the diarrhea and the urgency for treatment. This article will describe some of the more common causes of foal diarrhea and will review steps the owner can take to help assess the severity of the condition and urgency for veterinary care.
Causes of foal scours:
Foal Heat Scours
“Foal heat” refers to the mare’s first heat after foaling. Foal heat generally occurs between 7 and 11 days after foaling. Many mares ovulate around the 9th day, resulting in breeders referring to the foal heat as the “9-day heat.” Many foals experience mild diarrhea that coincides with the mare’s foal heat, generally between the 5th and 14th days after birth.
The actual cause of this diarrhea is unknown, but many experts believe it is due to normal gastrointestinal changes in the foal and is not caused by the mare’s heat. Foal heat scours is a mild, self-limiting diarrhea. Generally, it does not affect the foal’s appetite, energy, or hydration. Most cases will resolve without treatment within a few days, but it is important to monitor the foal closely to rule out other more serious causes of diarrhea that can also happen in this age group.
Viral Diarrhea
There are infectious agents that can also cause diarrhea. One of the more common of these is Rota Virus. Mares can harbor the virus without clinical signs and shed it in their feces. The virus can be shed directly from animal to animal. It can also be spread by objects that carry contaminated feces from one place to another, for example, from one stall to the next on someone’s boot.
The virus infects the lining of the intestines and causes sloughing of the surface layers. This results in decreased absorption from the intestine and increased secretion into the intestine. The end result is diarrhea, often fairly watery and with a foul odor.
Foals can have a mild fever, depression, and loss of appetite before the diarrhea starts. Fluid loss and decreased intake lead rapidly to dehydration. Electrolytes are depleted in the same manner.
Bacterial Diarrhea
There are numerous types of bacteria that have been identified as causing diarrhea in foals, such as Salmonella, Clostridium perfringens, and Clostridium difficile. Bacterial diarrhea often results in fever, bloody diarrhea, and gas distention of the intestines, which can lead to colicky symptoms.
Nutritional Diarrhea
The most common nutritional cause of diarrhea is related to the use of milk replacers in orphan foals. Some brands of milk replacer result in more problems than others. Problems can arise from improper mixing (both over-concentrated and under-concentrated milk cause problems).
Feeding frequency is another factor. Providing more feedings with smaller volumes each feeding will help reduce diarrhea. Consult with your veterinarian on specific feeding recommendations for orphan foals.
What the owner should look for:
Foal diarrhea and its consequences can vary from mild to rapidly life-threatening. There are several indicators the owner can monitor to help determine just how serious the foal’s condition is and how urgent it is to get veterinary assistance.
Energy Levels
Normal foals nurse very often, up to a hundred times a day the first few days of life. They are mentally very alert and love to play and investigate their surroundings. All this play helps them sleep soundly, which they also do often.
Familiarity with their normal activities helps owners recognize when foals are ADR (medical term for “Ain’t Doing Right”). If they have diarrhea but are bright and active, that is obviously encouraging and the problem is not serious. Keep monitoring, however, because this can change quickly. If they have diarrhea and are dull and lethargic, get help.
Nursing
An average mare produces between 3% and 3.5% of her body weight in liquid milk per day during peak lactation (between 6 and 10 weeks post partum). For a 1250lb. mare, that works out to nearly 45 lbs. of milk per day (over 5½ gallons a day).
The average beef cow is in the same ballpark for milk production. Why such a difference in udder size? It is because a foal nurses much more often than a calf. Consequently, the mare doesn’t have as much milk storage capacity.
The tightness of the mare’s udder (some breeders prefer to call it the “bag”) is therefore a great indicator of how well the foal is nursing. If the foal isn’t nursing, it won’t take long for the udder to become full, hard, and painful, possibly even streaming milk. If this is the case, you have a foal in trouble.
This assessment requires one to inspect and carefully feel the udder. A sick foal will sometimes nurse a bit when a person enters the stall or paddock just for security reasons. On closer inspection, the owner might discover the udder is distended because the foal hasn’t nursed for hours.
Temperature
The presence of a fever is indicative of an infection and obviously raises the level of concern and the urgency for veterinary assistance. However, a foal can have a normal temperature (between 99.0°F and 101.0°F) and still be seriously ill. When the temperature is normal, look at the things discussed above (energy levels and nursing) to help in your evaluation.
Consistency of Stool
Veterinarians, especially large animal veterinarians, have some interesting descriptive terms for stool. That is related to the fact that large animals produce a lot of the stuff and we’re constantly asking about it or examining it.
A couple of terms used for watery diarrhea are “garden hose” and “pipe stream” diarrhea. If your foal has this variety you’ve got a problem, even if it is a bright foal who is nursing normally and it is the right time for foal heat scours.
Frequency is another important factor. More frequent diarrhea translates into more rapid dehydration and electrolyte loss. Check the color, also. Black, tarry stools or blood-tinged stools are more serious.
Get veterinary help!
History, physical examination, and laboratory tests can help the veterinarian determine the cause of the diarrhea and appropriate therapy. Treatment often includes intravenous fluids to replace water and electrolyte losses. Oral intestinal protectants and ulcer medications are often prescribed (foals are particularly prone to gastric ulcers). Commonly, antibiotics are prescribed as well.
In summary, diarrhea is a common medical problem in foals. Foals, particularly young ones, do not have many reserves and they can deteriorate rapidly. Depending upon the cause, it can vary from very mild to very serious, rapid, and life-threatening. There are indicators that help an owner judge the seriousness of the problem. If the problem is serious, don’t wait a day—get your veterinarian out to help. If you are unsure, get on the phone and get your questions answered.
