Special considerations should be taken when evaluating a foal suffering a bout of colic.
Photo: Anne M. Eberhardt/The Horse
Although foals might look like mini versions of their adult counterparts, when it comes to treating them for health issues veterinarians often take a different approach than they would for a mature animal. Take colic for example. Most horse owners have an idea what they and veterinarians look for when dealing with a colicky horse, but what special considerations should be made for colicking foals? The differences might surprise you.
At the American Association of Equine Practitioners Focus on Colic Meeting, held July 24-26 in Indianapolis, Ind., Vanessa L. Cook, VetMB, MS, PhD, Dipl. ACVS, ACVECC, assistant professor in the Department of Large Animal Clinical Sciences at Michigan State University's College of Veterinary Medicine, discussed a systematic method by which veterinarians can evaluate colicky foals.
"Evaluation of the foal with colic is more challenging than in adult horses, particularly as the degree of pain is difficult to assess and rectal examination cannot be performed," she began. "However due to their size, abdominal radiography, ultrasound, and gastroscopy can be more readily performed."
Cook described the steps she takes when presented with a colicking foal to give him the best chance for survival. Not all the steps are needed in every case; however, it's important to ensure an accurate diagnosis.
Step 1: Obtain an Accurate History
"Because of the association of breed or age with specific condition in foals, it is important to start with basic information," she explained.
She always obtains information about the foal's age, any possible dystocia (difficult birth), the mare's history, and the foal's defecation, urination, and nursing history. She noted that these factors can all contribute to a foal displaying signs of colic.
"For example, congenital lesions, such as atretic (abnormal closure or absence of a body opening or tubular organ) portions of the gastrointestinal tract, are likely to manifest in the first few days of life, but not always in the first few hours as owners may expect," she said, adding that overo lethal white foals (who have a nonfunctional digestive tract and cannot pass manure) will present in a similar manner and in a similar time frame.
Step 2: Observation and Physical Examination
"The signs of colic in foals are slightly different to those of adults," Cook explained, noting some of the common differences that a veterinarian should consider when observing and performing a physical examination on a colicky foal:
- It's not uncommon for foals with colic to roll from side to side, or to exhibit dorsal recumbency (lying on their backs);
- Foals with medical problems (enteritis--inflammation of the intestinal tract--or gastric ulcers, for example) often show signs of severe pain, unlike their adult counterparts. Thus, "degree of pain is not as useful as an indicator of a surgical lesion as it is in adult horses with colic"; and
- Foals tend to have higher heart rates than adult horses (about 100 beats per minute in the first month, then decreasing to 60-70 beats per minute at 2 to 3 months old).
Veterinarians also have special considerations for heart murmurs in foals as compared to adult horses, Cook noted. She explained that in some cases, the ductus arteriosus (a shunt connecting the pulmonary artery to the aortic arch in a developing fetus; it allows most of the blood from the right ventricle to bypass the fetus's fluid-filled lungs) can remain in the foal for up to five days following birth, causing an abnormal murmur.
Finally, veterinarians will evaluate the foal for the presence of the meconium, or the foal's first feces.
"The meconium should be completely passed by 24 hours of age and is then followed by softer, lighter-colored feces," Cook explained. "A digital rectal examination can be performed to ensure the presence of feces and determine if meconium is still being passed."
She added that tan-colored "milk feces" have been known to pass around a high meconium impaction, so it's always best to ensure the foal has passed the meconium before eliminating that as a cause of colic.
Hernias should also be considered in foals exhibiting signs of colic, Cook said. An umbilical hernia (which occurs when a piece of intestine protrudes down into a body wall defect in the umbilicus, or navel area) sometimes requires surgical correction.
"An umbilical hernia only requires emergency surgical correction when the intestine is entrapped in the hernia and can no longer be easily pushed up into the foal's abdomen," Cook explained. "Most people will have the umbilical hernia corrected after the foal is weaned, mainly for cosmetic reasons."
A scrotal hernia (which is formed when the intestine slips down the inguinal canal and goes directly down into the scrotum) also requires surgical correction, especially if there is reddening or edema in the scrotum and prepuce. This is an indicator that the vaginal tunic (a membranous sac that extends from the abdominal cavity through the inguinal canal) has ruptured and the small intestine has shifted to lie just beneath the skin.
"This is dangerous because the intestine is no longer contained and can dissect underneath the skin with more and more coming out over time," she added.
Finally, Cook noted that an easy and efficient method for monitoring a possible obstruction in a colicky foal over a period of time is to objectively, sequentially measure abdominal girth. "This can be done by placing a piece of bailing twine around the same site of the abdomen and determining if the contour is increasing," she explained. "Evidence of the foal becoming more bloated suggests a complete obstruction and that surgery could be necessary."
Step 3: Abdominal Ultrasound
"This is an extremely useful tool for evaluating the colicky foal," Cook noted. "Due to their small size and shorter hair coat, ultrasound of the foal is easier and offers a more complete evaluation of the abdomen than in an adult horse."
She explained that veterinarians will look for the following factors when reading a foal's abdominal ultrasound:
- The small intestine's motility, wall thickness, and diameter to ensure all aspects of the organ are normal or healthy;
- Any nonmotile loops present in the small intestine, which could indicate an intestinal obstruction, enteritis, or ileus (the lack of progressive motility in the gastrointestinal tract);
- The size of the stomach to ensure normal emptying;
- Gas distension in the colon, which could indicate a large colon volvulus (twist) or colitis (inflammation of the colon);
- A high meconium impaction; and
- The peritoneal (abdominal) fluid volume ("Foals normally have very little peritoneal fluid, but an increase in volume is readily identified and most often indicates a uroperitoneum [urine in the abdominal cavity]," Cook said).
Step 4: Abdominocentesis
"Abdominocentesis (a belly tap) is extremely useful in foals with distended small intestine in order to differentiate small intestinal strangulation and enteritis," Cook noted, adding that there are several things peritoneal fluid can identify:
- An increase in total protein or cell count in the fluid can point toward either enteritis or intestinal strangulation;
- A serosanguinous (reddish-orange) color generally suggests an ischemic (decreased blood supply) intestine; and
- A peritoneal creatinine concentration more than twice the serum creatinine concentration is indicative of uroperitoneum.
Step 5: Nasogastric Tube
An important step to evaluating the colicky foal is the passage of a nasogastric tube.
"If gastric reflux is present, it could be due to a functional or mechanical small intestinal obstruction or a gastric outflow problem," Cook explained. "Fluid with a dark 'coffee grounds' appearance could indicate ulcer disease."
A nasogastric tube designed for an adult horse will not fit a foal's small organs, so Cook recommends using a stallion urinary catheter as an alternative.
Step 6: Abdominal Radiography
Seldom used to evaluate colic in adult horses, abdominal radiographs can be quite telling when observing a colicky foal.
"This technique is much more familiar to the small animal practitioner than the equine practitioner," Cook explained. "However, due to the inability to perform a rectal examination, plain and contrast abdominal radiographs can provide helpful information as to the location of the lesion."
These abdominal radiographs can identify a number of ailments including:
- Distended loops of intestine;
- Intestinal volvulus;
- Large colon gas distentions;
- Atretic sections of colon;
- Fecoliths (a hard concentration of ingesta);
- Meconium impactions; and
- Sand impactions.
Step 7: Gastroscopy
"If a gastric or duodenal ulceration is suspected, gastroscopy should be performed," Cook noted.
Gastroscopy is the most direct and scientifically accurate method currently available for confirming the presence or absence of gastric ulcers and should be considered for foals in which ulcers are a possibility.
"The esophagus should be evaluated as the endoscope is withdrawn to determine the presence of reflux esophagitis (inflammation of the esophagus from acidic stomach contents refluxing back up into the esophagus), which is frequently present concomitantly with gastric outflow obstruction," she added.
"The entire evaluation of the foal with colic is aimed towards determining what the potential problem is and if surgical treatment is necessary," Cook concluded. "The biggest dilemma is distinguishing a surgical lesion of the small or large intestine from enteritis and colitis. Unnecessary surgery should be avoided because of the high risk of postoperative adhesions; however, early surgical intervention prior to the onset of shock and sepsis results in an overall improved outcome in those foals that, in fact, need surgery."
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: Rabies Vaccination