Ivermectin toxicosis in a dog

A 5-year-old male Doberman Pinscher was examined after ingesting an equine paste dewormer containing approximately 115 mg of ivermectin. Clinical signs consisted of profound hypothermia, mild dehydration, dilated unresponsive pupils, localized muscle group fasciculations around the face and hind limbs, and no response to any external stimuli. Twelve days after parenteral administration of isotonic fluids and IV administration of dexamethasone and dimethyl sulfoxide, the dog returned to a clinically normal neurologic state. Ivermectin toxicosis has been reported frequently in Collies; however, other breeds may have idiosyncratic reactions to low doses. Patients with severe toxicosis should eventually recover completely if given appropriate intensive care.     

Megavesica in a neonatal foal

A newborn male foal was diagnosed with a greatly enlarged urinary bladder (megavesica), a urinary bladder diverticulum, and a herniated and abnormal umbilical remnant. Approximately 50% of the cranial bladder including the abnormal structures was surgically resected; the foal recovered and was still asymptomatic 15 months after surgery. The aetiology of megavesica in foals is unknown but successful outcome may be achieved with surgical intervention and adequate medical support.     

Gastrointestinal nonrotation in a neonatal foal

A 24‐hour‐old Welsh‐Thoroughbred foal presented for routine surgical repair of an abdominal and body wall hernia. The colt became acutely colicky and emergency celiotomy was performed revealing abnormal anatomical configuration of the gastrointestinal tract (GIT). Incomplete gastrointestinal rotation is a rare congenital anomaly only described in man. This report describes the clinical and diagnostic findings, surgical and medical treatment, and outcome of a neonatal foal with nonrotation of the GIT.     

Suspected ivermectin toxicosis in a miniature mule foal causing blindness

A 9-week-old miniature mule foal presented to the Veterinary Medical Teaching Hospital for acute blindness, ataxia, and depression following an overdose of an over-the-counter ivermectin-based de-worming medication. Ophthalmic examination and electrodiagnostic evaluation eliminated outer retinal abnormalities as the primary cause of the bilateral blindness, implicating instead a central neurologic effect of the drug. With symptomatic and supportive care, the foal recovered fully and regained its vision.     

Kernicterus in a neonatal foal.

A 5-day-old Thoroughbred foal was submitted to the necropsy service at the University of Kentucky Livestock Disease Diagnostic Center. The foal had a clinical history of seizure activity and severe icterus. A complete blood count and serum chemistry analysis indicated that the foal was anemic (hematocrit, 16%), hyperbilirubinemic (45 mg/dl), and hypoglycemic. At necropsy, all tissues were discolored various shades of yellow. Microscopically, there was degeneration and necrosis of cerebral neurons and cerebellar Purkinje cells; severe hepatocellular degeneration and necrosis; and deposition of amorphous golden-yellow material in the cerebellar granular cell layer, pulmonary alveoli, renal tubular epithelium, splenic trabecula, and the lamina propria of the small and large intestine. The golden-yellow material in the brain, lung, spleen, and small intestine was identified as bilirubin by histochemistry. Based on the macroscopic and microscopic findings, a diagnosis of kernicterus (bilirubin encephalopathy) was made. This report describes a rare case of equine neonatal kernicterus.     

Pulmonary coccidioidomycosis in a neonatal foal

A 13-day-old foal with profound tachypnoea and respiratory distress was examined. Thoracic radiographs revealed a severe, diffuse miliary pattern, and the foal was markedly hypoxaemic. It failed to improve with empirical treatment, and was euthanased. Lesions associated with Coccidioides immitis infection were identified at postmortem examination, and were limited to the lower respiratory tract.     

High-frequency jet ventilation in a neonatal foal

High-frequency jet ventilation was performed on a premature foal for respiratory difficulty attributable to in utero-acquired pneumonia. The procedure involves delivery of compressed gas through a small-bore cannula at frequencies up to 400 cycles/min. Ventilation settings of drive pressure, frequency, and FIO2 were varied to optimize PaO2 and PaCO2 values. The foal was ventilated with this equipment for 14 hours. Evidence of a favorable response to this method of ventilation was observed in the form of improvement in arterial blood gas values as well as the foal's attitude and degree of respiratory effort. High-frequency jet ventilation appears to be a useful method of ventilation for respiratory disease in neonatal foals; however, there remains no clear-cut advantage over conventional positive-pressure ventilation.     

Ivermectin plasma concentrations in collies sensitive to ivermectin-induced toxicosis

Five Collies sensitive to toxic effects of ivermectin and 7 nonsensitive Collies were given 100 micrograms of ivermectin/kg of body weight, PO. Blood samples were collected from each dog before treatment; at posttreatment hours 1, 2, 3.5, 5, and 8; and at posttreatment days 1, 2, 4, 7, 14, and 21. Each sample was assayed for ivermectin concentration, and statistical analyses were performed on the resulting plasma concentration data to determine differences in absorption and clearance of drugs between the 2 groups. Variables measured were area under the curve (using the trapezoidal rule), peak plasma concentration, and the time to peak concentration. Differences between sensitive and nonsensitive Collies for variables analyzed were not significant (P greater than 0.05).     

Self-limiting subepidermal bullous disease in a neonatal foal

A 1-day-old Appaloosa colt developed vesicles/bullae involving the skin of the lips and prepuce and multiple mucous membranes. Histopathology revealed subepidermal vesicles/bullae that were clear or contained variable numbers of neutrophils and erythrocytes. The separated epidermis appeared viable. The denuded dermal papillae were often disrupted by microabscesses or coated with fibrinosuppurative debris. Fragmented basement membrane components were attached to exposed dermal papillae. Immunoperoxidase staining of sections for deposition of IgG, IgM, IgA, and C3 were positive for IgG at the basement membrane and intercellular bridges. Complete recovery ensued. The characteristics of the subepidermal bullous lesions and clinical course of lesion resolution in this foal suggested a drug-induced pathogenesis. The only known drug exposure of the foal or mare was topical application of 7% iodine to the umbilicus at the time of foaling. Similar reactions to iodine administration have been reported in humans.     

Bilateral microphthalmos with cyst in a neonatal foal

A 1‐day–old miniature horse filly was presented to the University of Florida Veterinary Ophthalmology service for evaluation of multiple ocular anomalies which were present from birth. Protruding from the right orbit was a large, fluctuant, red, dry and variably ulcerated mass. A globe could not be appreciated clinically in the left orbit. Ocular ultrasound of both orbits was performed. This revealed a lobular, hypo‐echoic structure filling the right orbit, with multiple hyperechoic septations; normal ocular structures were not identified. Ultrasound of the left orbit revealed a microphthalmic eye, with a well‐defined, hyperechoic structure in the vitreous that was thought to be the lens. Due to irreversible blindness, the foal was humanely euthanized. Histopathology and immunohistochemistry of the orbital contents revealed bilateral microphthalmos with cyst, a congenital defect rarely reported in the veterinary literature.     

Transient diabetes mellitus in a neonatal Thoroughbred foal

Objective – To describe the clinical presentation, treatment, and outcome of a neonatal foal diagnosed with transient Type 1 diabetes mellitus. Case Summary – A 3‐day‐old Thoroughbred foal presented with a 24‐hour history of diarrhea and depression. Coronavirus particles were observed in the feces via electron microscopy. During hospitalization the foal developed hyperglycemia concomitantly with low insulin concentration and an adequate response to exogenous insulin therapy supported a diagnosis of Type 1 diabetes mellitus. The foal required SC insulin for 26 days, but developed complications associated with insulin therapy that resolved with appropriate care. On follow up assessment the foal was found to be a healthy euglycemic animal with normal insulin concentration at 11 months of age. New or Unique Information Provided – To our knowledge this is the first report of Type 1 diabetes in this age group and the first report of transient neonatal diabetes mellitus in horses. Type 1 diabetes mellitus should be considered a differential diagnosis for hyperglycemia in equine neonates and that it can be transient and managed successfully.     

Hypothyroidism and respiratory insufficiency in a neonatal foal

Hypothyroidism was diagnosed in a neonatal Thoroughbred foal that was weak, hypothermic, and septicemic. Administration of thyroid-releasing hormone elicited attenuated increases in concentrations of free and total triiodothyronine and thyroxine, as compared with a clinically normal, age-matched foal. The foal died of apparent respiratory insufficiency, pre- and postmortem findings compatible with hypothyroidism included hypothermia, large thyroid glands with distended, colloid-filled follicles, and severe, diffuse atelectasis, with thickened alveolar septae and degenerating alveolar squamous epithelial cells.     

Oxytetracycline associated acute kidney injury in a neonatal foal

A 3-day-old Australian Stock Horse filly presented with fulminant acute kidney injury after receiving 4 g of intravenous oxytetracycline at 24 and 48 h of age for medical management of flexural deformities. The filly’s clinical status initially improved, but worsening azotaemia prompted euthanasia after 55 h of supportive care. Necropsy confirmed proximal tubular necrosis. Nephropathy in association with oxytetracycline administration has been rarely reported. This case describes severe nephropathy in an apparently normal foal and highlights the need for thorough case evaluation prior to use of high-dose oxytetracycline therapy for correction of flexural deformities in foals.     

An unusual cause of colic in a neonatal foal

A case of a neonatal foal with acute colic and respiratory distress is described. The foal presented with signs of acute colic and was treated medically. The foal did not respond to treatment and 2 h after admission the foal began to demonstrate signs of respiratory distress. Thoracic and abdominal radiographs were obtained and a diagnosis of a diaphragmatic hernia was made. Surgical repair of the hernia was recommended but the owner declined and the foal was subjected to euthanasia. Post mortem findings confirmed the diagnosis and revealed that the defect was of congenital origin. Congenital diaphragmatic hernia is an unusual cause of colic in a neonatal foal.     

Volvulus of the large colon in a neonatal foal

A one‐day‐old Thoroughbred colt foal was presented for assessment of abdominal pain and reduced urine output. Physical examination of the foal revealed marked abdominal distension, mild tachycardia, tachypnoea and congested mucous membranes. A marked anechoic peritoneal effusion, intestinal hypomotility and mural thickening of the large colon were detected sonographically. Serosanguinous fluid was obtained by abdominocentesis. After haemodynamic stabilisation, the foal underwent general anaesthesia and exploratory laparotomy and a 720° volvulus of the large colon at the sternal and diaphragmatic flexures was identified. After correction of the volvulus, the intraoperative findings were consistent with nonviability of the affected portion of the colon. The owner declined partial colon resection and elected for euthanasia of the foal. Although rare in neonatal foals, large colon volvulus should be considered in foals with signs of abdominal pain, abdominal distension and ultrasonographic findings of colonic mural thickening and luminal distension.     

Urogenital problems in the neonatal foal

The common conditions affecting the urogenital tract of the neonatal foal and their medical and surgical management are described. Early recognition and treatment of serious abnormalities are necessary for a successful outcome in the equine neonate.