There are a number of GI problems that can arise in foals--some that are potentially life-threatening--so be on guard for clinical signs of these illnesses.
Photo: Anne M. Eberhardt/The Horse
When your foal takes his first breaths, the inner happenings of his gastrointestinal tract (GI) probably aren't your first concern. But there are a number of GI problems that could arise--some that are potentially life-threatening--so according to one Tufts University researcher, be on guard for clinical signs of these illnesses.
"The gastrointestinal system of the newborn foal is susceptible to many different problems in the first few days of life," explained Mary Rose Paradis, DVM, MS, Dipl. ACVIM (LAIM), an associate professor in the Department of Clinical Sciences at Tufts, in North Grafton, Mass. During a presentation at the 2011 Western Veterinary Conference, held Feb. 20-24 in Las Vegas, Nev., she discussed a few of the common gastrointestinal problems foals face in the early stages of life.
"Foals are often less tolerant of abdominal pain that adult horses," Paradis said. "But the good news is that the incidence of colic in the foal less than 6 months of age is about 18 times less than in the adult horse."
Clinical signs are relatively consistent across the gamut of GI disorders foals experience, and they include:
- Abdominal distension;
- Decreased nursing;
- Increased time lying down;
- Periods of dorsal recumbency (the foal lies on his back);
- Tail swishing ; and
- Straining to defecate.
The most common type of neonatal colic in foals 12-24 hours old is a meconium impaction. Normally meconium, the foal's first stool, is passed shortly after he consumes the mare's colostrum (typically within 12 hours of birth), but occasionally the foal is unable to pass the meconium.
Colostrum is special milk produced by the mare just before and immediately after the foal is born. It contains immunoglobulins that protect the foal from invading bacteria and will help keep him healthy until his own immune system is adequate, at about 8-10 weeks of age.
A veterinarian can generally determine if the foal has a meconium impaction by performing a digital examination, Paradis said, which is similar to a rectal exam in adults horses. Other diagnostic methods include abdominal radiographs and ultrasound.
She noted it's important not to attempt to manually remove the meconium out of the foal's rectum, as this could cause damage to the rectal mucosa. Most meconium impactions can be corrected by using enemas and/or oral laxatives. In rare cases (less than 1% of foals presented, Paradis added) surgery is required to correct the impaction.
"The prognosis is generally excellent in foals with meconium impaction," Paradis concluded.
As many as 50% of apparently healthy foals can suffer from gastric ulcers, Paradis noted, and this condition is more common in foals with orthopedic pain. The ulcers can vary in severity, with foals showing minor signs of hyperemic regions (an increase of blood flow to the tissues in an area, causing reddening) to deeper ulcers (apparent lesions within the stomach).
"If you have prolonged recumbency or decreased suckling, the pH of the foal's stomach can drop," Paradis said, noting that this acidity is what causes the ulcers to form. She added that up to 40% of sick foals have ulcers in the glandular portion of the stomach, which covers the bottom two-thirds of the stomach, secretes acid and pepsin (which are important aids in the early digestion of food) and has a protective barrier over the mucosal surface.
Paradis said that gastroscopy is the most direct and scientifically accurate method currently available for confirming gastric ulcers. This can be performed in the 45 kg (100 pound) foal with a meter long flexible endoscope.
Treatment includes the use of anti-ulcer medications (sucralfate, cimetidine, ranitidine, famotidine, and omeprazole can all be used in foals, she noted) and frequent feedings to balance the pH in the stomach are recommended. Paradis recommends that owners consult a veterinarian to ensure the foal is not overdosed with antiulcer medication. An overdose of antiulcer medication can alkalinize the stomach too much, allowing pathogenic bacteria to proliferate, Paradis said.
Paradis said that most foals will fully recover from gastic ulcers, however ruptured ulcers--although rare--are fatal should they occur.
Diarrhea in the Foal
"Interestingly, diarrhea, though sometimes life threatening due to severe dehydration, has a better prognosis with treatment than some of the other causes of illness in the foal such as pneumonia," Paradis began. "Because dehydration can occur rapidly it is important to seek medical help. It can be circumvented with fluid replacement. There are numerous causes that we find in the foal; often times we don't even find the root cause."
That being said, she added that it's important to try to determine the cause, as some are more dangerous to the foal than others, and with a diagnosis it is easier to provide accurate treatment. Some common causes of foal diarrhea include bacteria, viruses, and parasites. Other less common causes are gastric ulcers, prematurity, and lactose intolerance.
Bacterial diarrhea can can be caused by several different "bugs," including Clostridium perfringens, C. difficile, Salmonella, and bacteria from sepsis. Clostridial diarrhea can be watery to bloody, Paradis said, adding that there's a high mortality rate among affected foals. Salmonella-caused diarrhea varies in severity, Paradis said, but because the bacteria are able to translocate from the intestines to the bloodstream it can also produce high mortality rates. Once in the bloodstream, Salmonella can infect other organ systems, particularly growth plates in the bone and joints.
Rotavirus is one cause of viral diarrhea in foals, and affected foals generally receive a good prognosis, providing they receive treatment in a timely manner.
The most common parasite source of foal diarrhea is Strongyloides westeri (equine threadworm), which can be transmitted via the dam's milk.
Generally, veterinarians treat foal diarrhea with broad-spectrum antibiotics, along with intravenous fluids to combat the dehydration that often accompanies diarrhea. Paradis said that the addition of plasma to the treatment plan can help foals with low colloidal oncontic pressure (which keeps fluid from leaking out of the blood vessels). Paradis explained that protein in plasma--particularly albumin--has the ability to keep fluids in the blood vessels, rather than having it seep out as it does if the protein is low.
Additionally, she said, adding glucose to the intravenous fluids help to provide some nutrition to the foals.
One other type of foal diarrhea is foal heat diarrhea, termed so because of when it generally occurs--during the mare's foal heat. Paradis said the diarrhea is caused by "the normal maturation of intenstinal mucosa, and it's usually self limiting (i.e., it resolves on its own)."
Other Gastrointestinal Problems
Paradis also mentioned two other gastrointestinal problems foals can face: fecaliths and lethal white syndrome.
A fecalith is a hard concentration of ingesta--typically containing a large amount of hair--in the foal's digestive tract that presents like a meconium impaction. Paradis said she sees these most commonly in Miniature Horses. Veterinarians surgically remove fecaliths and foals generally recover from this surgery and mature normally.
Lethal white syndrome is a genetic gastrointestinal disorder that affects mainly foals from overo Paint mares and stallions. These foals are born all or mostly white ("It's possible have a small pigmented area around the face," Paradis added). The foals have an underdeveloped, contracted intestine caused by a failure of the embryonic cells to form nerves in the gastrointestinal system.
Because of the underdeveloped gastrointestinal system, foals are not able to pass the meconium (or any other manure). The condition is fatal, typically within 48 hours of birth.
Although there is no treatment, breeders can be proactive in testing mares and stallions to see if they are carriers for this genetic trait. Two carriers should not be bred to each other, however a carrier can be bred to a noncarrier and produce an unaffected foal.
About the Author
Erica Larson, news editor, holds a degree in journalism with an external specialty in equine science from Michigan State University in East Lansing. A Massachusetts native, she grew up in the saddle and has dabbled in a variety of disciplines including foxhunting, saddle seat, and mounted games. Currently, Erica competes in eventing with her OTTB, Dorado.
POLL: Colic Surgery