Congenital internal hydrocephalus in a quarter horse foal

Since the normal absorption of CSF occurs in the cerebral veins and venous sinuses, any obstruction to the normal flow and absorption of CSF will result in accumulation of CSF central to the site of obstruction. Such accumulation within the cranium is defined as hydrocephalus.A foal was presented with an enlarged and an abnormally-shaped skull, but with normal behavior. The filly's condition deteriorated. Radiographs showed a domeshaped cranial vault with compression of the frontal sinus region. Massive hydrocephalus with little normal cerebral tissue left was diagnosed with ultrasound.Surgery was attempted to relieve the pressure. Eventually the foal was euthanized. Post-mortem confirmed the radiographic and ultrasound diagnosis. Since there was a lack of demonstrable obstruction, the authors suspected the foal had suffered from the Arnold-Chiari syndrome.     

Tyzzer's disease in an 11-day-old foal

An 11-day-old pony became depressed, anorectic, and pyrexic 2 days after the topsoil of its paddock had been turned over. Rapid progression to colic and head pressing occurred, despite intensive therapy for Tyzzer's disease, and the foal died within 7 h of the appearance of central nervous system signs.     

Suspected selenium poisoning in a horse

A case of selenium poisoning was suspected following the administration of 325 micromol selenium a day as sodium selenate (25 mg Se) for five consecutive days. The main signs were confined to changes in the integument which were loss of hair from the mane and tail, disintegration of the skin of the anus, lips, prepuce and scrotum, and separation of the hooves from the coronary corium. Periodic analyses of blood, hair and hoof parings from the sole correlated strongly with blood and identified horn and hair as important additional routes of excretion.     

Suspected hepatic amyloidosis in a horse

A 9-year-old Saddlebred gelding was referred to the University of Wisconsin Veterinary Care for decreased energy levels, weight loss, persistently elevated liver enzymes, hyperglobulinaemia and leukocytosis. Abdominal ultrasonography showed a large volume of peritoneal fluid of mixed echogenicity, and the presence of focally distributed, circular to oval (approximately 1–2 cm), hyperechoic areas within the parenchyma of an enlarged liver. Cytological analysis of the peritoneal fluid revealed sterile neutrophilic/macrophagic inflammation, with haemosiderophages. A liver biopsy confirmed the presence of hepatic amyloidosis and focal fibrosis. Medical therapy with trimethoprim-sulfamethoxazole for 30 days and long-term dexamethasone was associated with both a clinical and biochemical response for 7 months, at which time the horse died from presumed hepatic rupture. To the authors’ knowledge, this is the first report describing potential successful management of hepatic amyloidosis in a horse.     

Suspected venous air embolism in a horse

A horse which had had a caecal impaction for 10 days was treated by means of an ileocolostomy [corrected] but failed to respond satisfactorily. Before a second laparotomy was performed it was observed to have dislodged the extension set from a jugular catheter and air was heard being sucked into the vein. It became very agitated but was anaesthetised again and the impaction was removed through an incision in the apex of the colon [corrected] After recovering from the anaesthesia it developed severe signs of pruritus which subsided only after 12 hours. These signs were considered most likely to have resulted from a venous air embolism.     

Suspected swainsonine poisoning in a Belgian horse

The case of a horse with acute symptoms of excitement, exaggerated fright reactions and trembling is presented. In addition to these cerebral symptoms, mild cerebellar ataxia and a renal tubular lesion were diagnosed. Suspected swainsonine poisoning was confirmed by the presence of the toxin (154 ng/ml) in the serum sample taken immediately after admission. A good recovery was seen after fluid therapy with supplementation of potassium, a dopamine drip and administration of diazepam. The effects of the toxin, by inhibiting the lysosomal enzyme α‐mannosidase and mimicking the genetic mannosidosis, are discussed.     

Severe hyperkalaemia associated with renal dysplasia in a 2-day-old foal

A 2-day-old filly foal presented with signs of depression, recumbency and inappetence. Blood analyses revealed hypoalbuminaemia, hyperfibrinogenaemia, hyperglycaemia and hyperkalaemia. The foal deteriorated despite intensive treatment and was subjected to euthanasia. At post mortem examination, the urinary bladder, ureters and kidneys appeared normal grossly. Histologically both kidneys showed disorganised development with the presence of structures inappropriate for a foal of this age, including primitive glomeruli, immature renal tubules and persistent metanephric ducts. Based on these findings a diagnosis of bilateral renal dysplasia was made.     

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.     

Bone abscess in the mandible of a quarter horse gelding

A 4-year-old Quarter horse gelding presented with a swelling in the soft tissues over the junction of the body and ramus of the left mandible. Radiography showed a well circumscribed lytic area within the mandible surrounded by sclerosis unassociated with any tooth. Aspiration of the lesion yielded pus. The abscess cavity was opened, curetted and lavaged. A Penrose drain was placed in the abscess cavity for 10 days. Bacteriological culture of the exudate and soft tissues from the abscess produced a few colonies of Staphylococcus intermedius. Histopathology showed chronic pyogenic infection. The horse recovered well and was normal 1 year after treatment.     

Equine herpesvirus myeloencephalopathy in a 14-year-old quarter horse stallion

A 14-year-old, quarter horse stallion was presented in lateral recumbency, unable to rise. Equine herpesvirus myeloencephalopathy was diagnosed, based on presentation, clinical signs, and the ruling out of other possibilities. After initial rapid improvements, ataxia remained, as did chronic cystitis secondary to bladder paralysis. He was euthanized after 2 months.