Induction of early-phase endotoxin tolerance in horses.

Six, clinically healthy horses, of mixed age and sex, were infused via a jugular venous catheter with 100 ml of pyrogenfree sterile saline (PFSS; 0.9% NaCl). Animals were infused with Escherichia coli O55:B5 endotoxin (total dose = 50 ng/kg bwt), 24 (LPS-1) and 48 h (LPS-2) after PFSS infusion. Blood was collected before, and every 15 min after, each infusion for the first 8 h and then every 2 h for the following 14 h. Clinical responses (rectal temperature, heart rate, respiration rate and blood pressure) were determined before and every 4 h after each infusion for 20 h. Geometric mean anti-endotoxin antibody titres in serum samples, harvested just before each infusion, were unchanged over the course of the experiment. Serum tumour necrosis factor-alpha (TNF alpha) activity was estimated using a cytotoxic bioassay and WEHI 164 clone 13 murine fibrosarcoma cells as targets. Mean clinical parameter values and geometric mean serum TNF alpha activity at given time points were compared across the 3 infusions. Both LPS-1 and LPS-2 resulted in elevated mean rectal temperature at 4 h after infusion. However, duration of mean rectal temperature elevation was greater (P < 0.05) after LPS-1 (through 12 h) than after LPS-2 (through 8 h). More substantial increases in systolic and diastolic blood pressure were observed after LPS-1 than LPS-2 and mean systolic blood pressure after LPS-1 was elevated at 4 h when compared to PFSS (P < 0.05). Decreased systolic and diastolic blood pressures were observed at 16 h after both LPS infusions, when compared to PFSS infusion. Heart rate was increased, compared to PFSS, after both LPS-1 (8-12 h) and LPS-2 (4-12 h) (P < 0.05). No significant elevations in mean respiratory rate were observed after either LPS-1 or LPS-2 when compared to PFSS. However, at 4 h post infusion, mean respiratory rate after LPS-2 was greater (P < 0.05) than that after LPS-1. Serum TNF alpha activity was not detected after infusion of PFSS, but was detected after both LPS-1 and LPS-2. Serum TNF alpha activity was elevated earlier, was present in higher concentrations and persisted longer after LPS-1 than after LPS-2 (P < 0.05). The decreased duration of fever and attenuated serum TNF alpha response subsequent to successive sublethal LPS challenge observed in this study support the conclusion that these horses developed early-phase endotoxin tolerance (EPET) and, therefore, contributes to the understanding of the role of endotoxaemia in a number of clinical conditions in horses.

Jejunal intussusception: a complication of functional end-to-end stapled anastomoses in two ponies.

Jejunojejunal intussusception occurred after jejunal resection and stapled functional end-to-end anastomosis in two pony mares. In both mares, the lead point of the intussusception was the stapled functional end-to-end (FEE) anastomosis. The stapled free ends of jejunum were oversewn with an inverting suture pattern. A possible explanation for development of the intussusception was the acute angle created in the intestine by the FEE anastomosis. This angulation may have impaired flow of ingesta causing motility changes that predisposed the site to intussusception. Because the oversewn blind intestinal ends acted as the lead point for formation of the intussusception, it may be inadvisable to oversew the stapled anastomotic ends.

Chyloabdomen in a neonatal foal.

A 12-hour-old female standardbred foal developed signs of abdominal pain, tachycardia, tachypnoea and fever associated with chylous ascites. Small intestinal obstruction was due to segmental, mid-jejunal lymphangiectasia. Post mortem examination revealed a lack of communication between afferent and efferent lymphatic vessels in the mesenteric lymphocentre, a defect which was suspected to be congenital.

Disseminated peritoneal leiomyomatosis in a horse.

A 6-year-old female Quarter Horse became inappetent, lost weight, was febrile, and had abdominal enlargement and infrequent bouts of mild colic. Palpation per rectum detected a prominent, smooth-walled mass adjacent to the pelvic flexure of the colon. Analyses revealed the peritoneal fluid was apparently normal except for a high protein concentration. By the use of ultrasonography, the mass was observed adjacent to the body wall in many locations throughout the abdomen, appearing as an irregular, multiloculated structure composed of innumerable cysts of various sizes with interspersed, circular hyperechoic nodules. A celiotomy was performed, and the 34-kg mass was removed. On the basis of histologic examination, a diagnosis of disseminated peritoneal leiomyomatosis was made. The horse had an uncomplicated recovery and gained weight. Further problems have not been reported and the horse subsequently gave birth to a healthy foal. A complete examination of the horse 22 months after surgery did not reveal signs of redevelopment of the condition.

Use of esophagoscopy in the diagnosis of esophageal squamous cell carcinoma in a horse.

Esophagoscopy allowed visualization and biopsy of a lesion within a diverticulum of the esophagus in an adult horse. Although the biopsy specimen obtained was small, diagnosis of squamous cell carcinoma was possible from histologic examination of the esophageal tissue sample retrieved by use of endoscopy.