The Horse:Your Guide To Equine Health Care provides monthly equine health care information to horse owners, breeders, veterinarians, barn/farm managers, trainer/riding instructors, and others involved in the hands-on care of the horse.
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31 December 2017 THE HORSE TheHorse.com ■ Impacted horses' hindgut fermentation. They found that moxidectin reduced hay and oat fermentation 16 hours post- treatment, but bacterial diversity did not change significantly. They did not detect a change in bacterial metabolite output. Colicky Foals: Diagnostics and Decision-Making Foals present unique diagnostic and treatment challenges in the face of colic. Samuel Hurcombe, BSc, BVMS (Hons), MS, Dipl. ACVIM, ACVECC, reviewed how to address these young patients. Types of colic veterinarians commonly report in foals include meconium (the first manure) impaction, hernias, enteritis/ colitis, uroabdomen (urine in the abdo- men), gastric ulcerative disease, small intestine volvulus, intestinal adhesions, and congenital abnormalities. Less com- monly they see large colon disease such as displacements or volvulus, he said. Challenges veterinarians face include: ■ Small patient size ; ■ Co-morbidities Colicking foals often have a concurrent disease process, such as sepsis (systemic infection), neonatal maladjustment syndrome (aka dummy foals), prematurity/dysmaturity, dehy- dration, or failure of passive transfer, said Hurcombe; and ■ Heightened metabolic needs You don't want to withhold feed from a colicking foal as you would an adult. In a foal with colic signs, Hurcombe said the veterinarian should make imme- diate note of the foal's signalment (breed, sex, etc.) and history and know that some lesions are overrepresented in certain breeds and genders. When taking the foal's history, im- portant information includes the mare's health, whether she had a dystocia (dif- ficult birth), parturition details, housing conditions, and the farm's disease history. "These are very important in determin- ing risk for infectious disease," he said. Colic signs in foals differ from those in adults and include lying on the back, roll- ing from side to side, decreased nursing, changes in abdominal contour, bruxism (teeth grinding), sudden decreased urine production, and postural changes such as back-arching and tail-flagging. "Pain alone is very unspecific and is not really good at delineating medical vs. surgical colic," in foals, said Hurcombe. He then listed the veterinarian's diagnostic options and how he or she performs them. Physical exam After administering seda- tives and/or analgesics (pain- relievers), the vet can assess: ■ Temperature, pulse, and respiration; ■ Perfusion (the cardiovascular system's status and functionality), "because when foals crash, they crash quickly," said Hurcombe; ■ Pain levels; ■ Abdominal distention, as occurs in foals with meconium impaction. "Using a measuring tape around the abdomen, take the circumference every hour or so," he said; and ■ Structures such as the scrotum and umbilicus for sign of herniation. Nasogastric intubation This step in the foal's examination is essential, said Hurcombe, but requires patience. "Given their size, smaller lubricated tubes are required to avoid unnecessary nasopharyngeal and esophageal trauma," he said. "A stallion urinary catheter works well in most neonatal foals." Digital exam Due to the foal's size, the veterinarian will need to use a well- lubricated gloved finger (and probably sedation) to perform a rectal exam. This step can help detect impacted meconium. Abdominal ultrasound This tool is extremely useful for making a diagnosis in foals, in particular. "The small size, thin body wall, and thin hair coat make the utility of this technology high for determining the location of the lesions, presence of distention, thickness of visceral wall, peritoneal effusion (fluid accumulation), or structural abnormali- ties," said Hurcombe. Abdominal radiography (X rays) Simi- larly, radiographs are far more useful in foals than in adults and can help veteri- narians determine the affected anatomi- cal region in obstruction cases. Abdominocentesis This procedure—a belly tap to sample abdominal fluid—can be performed with the foal standing or lying down, with or without ultrasound guidance, and doesn't differ much from that performed in adults. Foal cell counts, protein levels, etc., however, are different from adults', Hurcombe cautioned. Gastroscopy Veterinarians can easily diagnose gastric ulcerative disease and mass lesions by viewing the foal's stomach via a camera passed through the nostril. "For neonatal foals, a 1-meter scope is usually long enough to assess the esopha- gus, stomach, and pyloric outflow tract," said Hurcombe. "A small outer diameter human pediatric endoscope may be required in Miniature foals." If the foal requires more advanced diagnostics than the treating veterinar- ian can provide, is in severe pain, or has concurrent sepsis or metabolic problems, Hurcombe recommended referral. Surgical intervention Based on the scientific literature, neonates have a worse prognosis for survival after colic surgery than older foals and adults, said Hurcombe. This can be attributed to their increased risk of intestinal adhesions, their delicate tissues, and their compli- cated postoperative care. Ultimately, said Hurcombe, prognosis is lesion-dependent. "It's excellent for meconium impactions and other medical colics without concurrent disease," he said. "It's good for simple obstructions or impactions and decreases with sepsis. Small intestine lesions have a guarded long-term prognosis." Indicators to go to surgery can include: ■ Persistent pain that's unresponsive to analgesics; ■ Persistent tachycardia (rapid heart rate); ■ Progressive abdominal distention; ■ Increased peritoneal fluid protein or cell counts; ■ Serosanguinous (reddish-orange) peri- toneal fluid; ■ Diagnostic evidence of obstruction; and ■ Worsening clinical signs despite medi- cal management. Hurcombe recommended proceeding with surgery only if the owner is aware of the benefits, risks, and prognosis. h Clinical signs of colic and diagnostic tech- niques used in foals differ from those of adults. PAULA DA SILVA