الكاتب: Multiple References

A6½-month-old Morgan filly was examined because of a history of abnormal behavior, teeth grinding, hypothermia, and electrolyte disturbances when weaned. She was from a breeding farm with several other Morgan horses. The 11-year-old dam had been purchased the year before as a proven broodmare, which had several previous foals. Breeding, gestation, and birth of this foal were normal. She was raised with 4 other mares and their offspring on pasture with free access to shelter in an open barn. Supplementary feeding consisted of oats and timothy hay. The owners reported that the foal showed unusual behavior, such as lack of apprehension of people, lack of distress from maternal separation, and a higher activity level than other foals of the same age. The foal extensively chewed the dam’s tail and mane, masticated oats slowly with rapid jaw movements without actually swallowing them, and ground her teeth. She frequently nibbled the handler’s clothes without biting, ate pebbles, and played with the salt block in the paddock. At 4½ months of age, she was treated for suspected gastroduodenal ulcers and weaned. The referring veterinarian examined her 5 days after weaning because of dull demeanor and excessive teeth grinding. The foal was in thin body condition, hypothermic (378C, 98.68F), and tachycardic (60 beats per minute [bpm]) and had decreased borborygmi. Major abnormalities on serum biochemistry were severe hypernatremia (166 mmol/L; reference range 136–144 mmol/L) and hyperchloremia (128 mmol/L; reference range 94–104 mmol/L), azotemia (urea, 11.3 mmol/L; reference range 4.2–8.9 mmol/L), and hyperfibrinogenemia (5.2 g/L, reference range 1.6–2.9 g/L). The only abnormality on the CBC was hemoconcentration (PCV, 0.57 L/L; reference range 0.28–0.44 L/L). The foal was treated with penicillin procaine Ga (20,000 IU/kg [9072 IU/lb] IM q12h) and rifampinb (5 mg/kg [2.7 mg/lb] PO q8h). The next day the tachycardia worsened (120 bpm) and the foal was estimated to be 5–8% dehydrated. IV fluid therapy with lactated Ringer solutionc (LRS) was initiated,