Older foals can suffer from a variety of potentially life-threatening illnesses and medical conditions.
Photo: Anne M. Eberhardt/The Horse
Growing foals can suffer a range of potentially life-threatening illnesses and conditions, such as pneumonia, colic, and ulcers. At a recent veterinary convention, one practitioner stressed the importance of recognizing these conditions and their clinical signs, as prompt veterinary attention often gives the patient the best chance for survival.
During a presentation at the 2012 Western Veterinary Conference, held Feb. 19-23 in Las Vegas, Nev., Carol Clark, DVM, Dipl. ACVIM, a practitioner at Peterson & Smith Equine Hospital in Ocala, Fla., gave a brief overview of several select health conditions that foals aged 2 weeks and over often battle.
Before beginning, Clark emphasized, "Sick or stressed foals are much more at risk for developing (ulcers) than neonates or adults. Any sick foal older than 2 weeks of age should be on ulcer prophylaxis until it is healthy again."
Gastroduodenal Ulcer Disease (GDUD)--As the name suggests, GDUD involves ulcer development in the stomach's glandular or nonglandular mucosa, the duodenum, or the esophagus.. Clinical signs of GDUD include depression, anorexia, diarrhea, fever, gastric reflux, teeth grinding, excessive salivation, weight loss, pica (consuming nonfood items), and colic.
"A presumptive diagnosis of GDUD can be made by (evaluating) clinical signs and response to treatment," Clark said. "Endoscopy provides the definitive diagnosis." Abdominal radiographs (X rays) might also be useful to visualize fluid distention of the stomach, she noted, and barium studies can reveal delayed gastric emptying or obstructions.
Clark said GDUD treatment typically lasts for about a month. She recommends anti-ulcer medications such as ranitidine and/or a proton pump inhibitor (i.e., GastroGard or Ulcer Gard). Other anti-ulcer medication options include sucralfate, misoprostol, bismuth, and aluminum/magnesium antacids, she added. She advised against treating pain with non-steroidal anti-inflammatory drugs (NSAIDs) and recommended using either xylazine (an alpha-2 agonist) or butorphanol (a morphine derivative) instead.
"Follow up endoscopy (to ensure complete resolution) is highly recommended with severe cases," she added.
Strangulated Umbilical Hernias--"There are two forms of this syndrome: strangulated peritoneal fat with resulting necrosis or intestinal incarceration," Clark said.
Both forms of strangulated umbilical hernia are identifiable as hernias that could at one point be pushed back into the foal's abdomen, but are no longer reducible, she said. Otherwise, the two forms tend to have different presentations.
"Abdominal discomfort ensues with the intestinal compromised foals displaying more unrelenting pain," Clark explained. "The fat necrosis foals will usually have a larger area of swelling that is more painful to palpation and often accompanied by fever; their colic pain is mild." A veterinarian can also perform an ultrasound examination and a belly tap (abdominocentesis) to help differentiate between the two forms, she added.
The fat necrosis foals typically respond to treatment with antibiotics, NSAIDs, and analgesics, while the intestinally compromised foals require surgery.
Ascarid (Roundworm) Impactions--"Ascarid impactions are most often seen after deworming when the dying parasites obstruct the small intestine," Clark explained.
An owner or veterinarian should suspect an ascarid impaction if the foal colics shortly after being dewormed or if intact ascarids are visible in manure or gastric reflux, she said. An ultrasound of the abdomen could reveal small intestinal distention, and on occasion the parasites are visible via ultrasound, Clark added.
Clark said medical treatment for ascarid impactions includes mineral oil administration via a nasogastric tube, analgesics, and intravenous fluids. If the foal produces gastric reflux, the veterinarian might implement food and water restrictions, she said. In some cases surgery is necessary to remove the obstruction.
Upon resolution, Clark recommends administering a full or larvicidal dose of fenbendazole at least monthly for two to three months. She noted that parasite resistance appears to be developing to avermectins and pyrantel products and that these formulations are often less effective.
Sand Ingestion--In sandy regions foals are known to consume "large quantities" of sand, which results in a colon obstruction, Clark said. These foals typically present with intermittent diarrhea and colic and often develop GDUD at the same time, she noted. "Foals with sand colic and/or diarrhea have a distinct smell," Clark added. "Some have described it as 'fishy.' "
A diagnosis of sand colic can be made via abdominal radiography, and sand is typicall visible with a fecal float and upon a digital rectal examination, she said.
A veterinarian should administer mineral oil via a nasogastric tube and daily psyllium for several weeks to treat this condition, Clark said. Once the condition has resolved, she recommends feeding psyllium one week each month indefinitely and removing the foal from sandy areas, if possible.
"Most foals grow out of this pica, and rarely is surgery required to empty the sand from their colons," Clark said.
Rotavirus--This virus, which causes profuse yellowish diarrhea, has a high morbidity (illness) rate on endemic farms, but thankfully a low mortality (death) rate, Clark said. Clinical signs typically include fever, mild colic, and inappetence. Veterinarians diagnose this condition by coupling clinical signs with an antigen detecting test.
"Diagnosis is important because preventative measures, such as mare vaccination, can be implemented in subsequent years," Clark said.
Clark relayed that rotavirus treatment includes electrolyte and fluid replacement, gastrointestinal tract absorbents, and antibiotics. She also noted that many foals with rotavirus develop gastric ulcers, so she also recommends starting affected foals on ulcer treatment.
Most foals recover from rotavirus. Those that succumb typically do so due to untreated hypervolemia (a thickening of the blood due to an increase in red blood cell numbers), acidosis (unusually acidic blood from diarrhea), or electrolyte loss, Clark said.
Peritonitis--Peritonitis is an inflammation of the peritoneum, or the membrane lining the abdomen, caused by gastric ulcers, umbilical infections, gastrointestinal leakage due to enterocolitis (inflammation of the small intestine and colon), or ascarid impaction, Clark said. Mild colic, a reluctance to move, pain spurred by abdominal palpation, fever, depression, endotoxemia, and ileus (lack of gut motility) are all common clinical signs of peritonitis, she added.
Veterinarians diagnose peritonitis using ultrasound and abdominocentesis.
"Early surgical intervention can be curative and prevent advanced peritonitis, septic arthritis, and/or abdominal adhesions," Clark said.
Equine Proliferative Enteropathy--Caused by the bacteria Lawsonia intracellularis, equine proliferative enteropathy (EPE) is most commonly seen in recently weaned foals, Clark said. Clinical signs of EPE include lethargy, unthriftyness, colic, diarrhea, and weight loss. Affected foals also develop thickened intestinal walls, which leads to malabsorption of protein and a low daily weight gain.
Clark said veterinarians use a combination of clinical signs, low protein levels, serology, and a fecal PCR (polymerase chain reaction) test to diagnose the disorder. Treatment is often prolonged--at least two to four weeks--oral antibiotics, including doxycycline and chloramphenicol, or a macrolide/rifampin combination. In more severe cases, she noted, blood plasma transfusions might be indicated. She also recommends treating affected foals for gastric ulcers.
Most foals recover successfully from EPE, although they tend to take slightly longer than their healthy counterparts to reach adult size.
Rhodococcus equi Pneumonia--Clinical signs of pneumonia caused by the pathogen Rhodococcus equi include cough, a mucopurulent (thick, greenish-white) nasal discharge, high fever, lethargy, depression, weight loss, an increased respiratory rate, and progressive respiratory distress. Clark said veterinarians typically make a presumptive diagnosis by combining clinical signs with a complete blood count showing an elevated white blood cell count and hyperfibrinogenemia (excessive fibrinogen in the blood). A thoracic ultrasound can be useful in the diagnosis of R. equi pneumonia, she added, and veterinarians use a tracheal culture to confirm the diagnosis.
Clark relayed that treatment of mild cases includes doxycyline or rifampin administration. More severe cases typically necessitate treatment with a macrolide and rifampin. She also recommended the concurrent use of probiotics and anti-ulcer treatment. "Antibiotic therapy is generally prolonged--at least three weeks," she said.
Extrapulmonary R. equi pneumonia infections include osteomyelitis, septic arthritis, uveitis, diarrhea, and abdominal abscesses, she said.
Bacterial Pneumonia--Typically caused by Streptococcus sp., bacterial pneumonia often follows viral pneumonia, Clark said. Clinical signs include fever, depression, inappetence, nasal discharge, coughing, respiratory distress, and abnormal lung sounds. A definitive diagnosis is often reached via tracheal culture and cytology, she said.
"Appropriate antibiotics, judicious NSAIDs to control (fever), and ulcer prophylaxis are indicated for treatment," Clark said. If the foal also shows signs of small airway inflammation, a veterinarian might administer corticosteroids and wean the foal off them gradually over two to three weeks.
Interstitial Pneumonia--Sometimes called juvenile hyperreactive airway disease, Clark said interstitial pneumonia (or pneumonia that develops in the area between where the gas is exchanged in the lungs [called the alveoli]) is a poorly understood condition.
She relayed that affected foals develop clinical signs very rapidly ("Some of these foals can present suddenly with very little history of respiratory signs and be dead in 24 to 48 hours," she said.), These can include rapid, shallow breathing; increased respiratory effort; and wheezing and/or crackling sounds during breathing. Veterinarians diagnose interstitial in the same general manner as R. equi pneumonia: a combination of clinical signs, a complete blood count, thoracic ultrasound, and tracheal culture.
"Therapy is aimed at reducing inflammation and increasing oxygen delivery," Clark said. Treatment modalities include:
- Inhaled or systemic corticosteroids;
- Inhaled or systemic bronchodilators;
- Intranasal oxygen, as needed; and
- Broad-spectrum antibiotics.
The prognosis for foals with interstitial pneumonia is fair to guarded if the animal's condition doesn't improve in 24 to 48 hours, Clark said.
When raising foals, it's important to know which ailments they could develop as they age, as well as the necessary steps to give a sick foal the best chance for recovery.
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: University Equine Hospitals