GRANULOMATOUS MENINGOENCEPHALOMYELITIS IN A DOG

Clinical and pathological findings in a 2.5-year-old speyed female dog with granulomatous meningoencephalomyelitis are described. The clinical course was progressive with the major neurological signs being referable to the posterior brain stem and cerebellum. Histological examination of the brain revealed a multifocal granulomatous meningoencephalitis predominantly associated with the blood vessels of the white matter.     

THE ACUTE ABDOMEN IN THE HORSE EPIDEMIOLOGIC CONSIDERATIONS

A retrospective case history study of acute gastro-intestinal disease in the horse was undertaken to determine: 1) if a statistically significant age, sex, or breed distribution existed; 2) if a correlation existed between duration of clinical signs and surgical complications; and, 3) if the lesions causing the signs significantly altered surgical prognosis. Significant age, sex and breed distributions existed. Duration of clinical signs ranged to 5 days with a definitive time trend existing for surgical correction of strangulating colics. Surgical correction was successful only within 24 hours of the appearance of clinical signs. Surgical prognosis for specific intraabdominal lesions ranged from 20% survival with strangulation obstructions to 84% with impaction. Differential diagnosis in horses with signs of acute abdominal pain is difficult, and techniques available for this purpose are limited. ^3,7,8 Differentiation of specific lesions is necessary because the prognosis varies greatly with each, and the choice of treatment used depends on the nature of the lesion.¹ Knowledge of significant age, sex, or breed related distributions would aid differential diagnosis. There are few epidemiologic reports available for use in the clinical management of these cases.⁴ A recent report has dealt with the relative incidence of various types of intestinal obstructive diseases in the horse.⁷ The purpose of this retrospective case history study of gastrointestinal disorders in the horse was to determine: 1. If a statistically significant age, sex or breed distribution existed for all or specific lesions; 2. If a correlation existed between duration of clinical signs and surgical survival; and 3. If the lesions causing the clinical signs significantly altered surgical prognosis.     

METABOLIC MANAGEMENT OF THE HORSE WITH ACUTE ABDOMINAL CRISIS*

The horse with an abdominal crisis caused by acute gastro-intestinal tract obstruction develops hypovolemia, hemoconcentration, electrolyte depletion, metabolic acidosis and shock. During preparation for operation, treatment with fluids, antibiotics and bicarbonate will impede metabolic imbalance. Stomach decompression may slow the passage of sodium, water and potassium to the gut lumen, reduce pain and minimize the risk of stomach rupture. Selected laboratory determinations and the monitoring of arterial and venous pressures will provide a measure of severity and serve as a guide to replacement therapy. In the post surgical period, vigilance must be directed towards potassium and bicarbonate imbalanc and adequate hydration.     

BACTERIAL ENDOCARDITIS WITH THROMBUS FORMATION AND ABSCESSATION IN A HORSE

A 2.5 year old Appaloosa stallion with progressive weight loss and a heart murmur was diagnosed as having vegetative endocarditis of the right atrioventricular valves with a mass in the right atrium. The ultrasonographic appearance of the lesion was characterized by extreme reverberation. On postmortem examination, a 9 cm diameter thrombus was found within the right atrium and auricle, occupying approximately 80% of the chamber volume. Additionally, a lenticular abscess extended throughout the parietal cusp of the right atrioventricular valve. Histologic examination revealed that the lesions were septic with numerous gram positive cocci in short chains, suggestive of Streptococcus equi , and gram negative rods.     

INFERTILITY IN THE HORSE ASSOCIATED WITH CHROMOSOMAL ABNORMALITIES

SUMMARY Reproductive failure was studied in 12 phenotypically normal mares (9 Arabian, 3 Quarter horses, 1 Appaloosa and 1 pony). Karyotyping was performed using lymphocytes isolated from peripheral blood by density gradient procedures, followed by standard culture methods for karyotyping. Nine mares had karyotypes of 63,XO; 1 had 63,XO/64,XX; 1 had 63,XO/64,XY and 1 had 64,XY. All mares had small, firm ovaries that when removed and examined from 4 mares, lacked germ cells and consisted of undifferentiated ovarian stroma.     

PARAESOPHAGEAL CYST IN A HORSE

A 2 year old Morgan gelding was evaluated for a non-painful mass located caudodorsal to the larynx. Radiographically, the mass was ovoid shaped and had a peripheral rim of mineralization. Slight ventral displacement of the dorsal margin of the trachea could also be identified. Uniform moderate level echoes were seen throughout the interior of the mass on ultrasound examination. An esophagram was performed and demonstrated displacement without involvement of the esophagus by the mass. The esophagus appeared as a separate structure from the mass on both the ultrasound examination and esophagram. During surgical removal, the mass also appeared as a distinct structure from the esophagus. Histologically, the mass was consistent with an epithelial inclusion cyst which originated from the esophagus.     

OSSIFYING AMELOBLASTOMA IN A HORSE

The features of an ossifying ameloblastoma in a 5-year-old gelding are described. The tumour developed in the angle of the right mandible and microscopically consisted of multiple follicles and islands of epithelial tissue adjacent to which were trabeculae of bone, osteoid and compact collagenous tissue.