Coxofemoral luxation in a horse during recovery from general anaesthesia

Autor: C. M. Walsh, K. Portier
Rok vydání: 2006
Předmět:
Zdroj: The Veterinary record. 159(3)
ISSN: 0042-4900
Popis: COXOFEMORAL luxation is uncommon in horses, but when it does occur it most often affects young foals or ponies. To the authors’ our knowledge, dislocation has not previously been reported in an adult horse during recovery from general anaesthesia. This case report describes a coxofemoral dislocation in a horse during a calm recovery from general anaesthesia. A 16-year-old entire male Selle Francais riding horse, weighing 496 kg, was presented with a history of suspected chronic (two to three months duration) bilateral inguinal hernia. The horse had not shown signs of pain during this period. Seven years previously, a painful inguinal hernia had been manually reduced, and two years after that equine motor neurone disease (EMND) had been diagnosed, when the horse was presented with shivering, prolonged decubitus and hindlimb stiffness. Clinical examination at that time had revealed pronounced symmetrical muscle atrophy, but no ataxia, and no neurological signs had been observed apart from sweating on the left side of the head, characteristic of Horner’s syndrome. Biochemical examination had revealed a marked increase in creatinine kinase (408 U/l), lactate dehydrogenase (>2000 U/l), and aspartate transaminase (>1000 U/l), consistent with the presence of muscular disease. A decrease in vitamin E (0·21 mg/l) and increase in superoxide dismutase (>800 U/l) were also observed. All these clinical and biochemical signs had been suggestive of EMND. Improvement was observed during treatment with vitamin E (8000 U once daily orally) and prednisolone (1 mg/kg once daily for one month). The progression of the disease stopped, but the horse failed to gain weight and showed exercise intolerance and muscle atrophy, which are common clinical complaints observed in the arrested form of the disease (Divers and others 1997). On this occasion, clinical examination revealed an increase in testicular size and induration. Transrectal palpation and an ultrasound scan of the scrotum confirmed an inguinal hernia of the small intestine with abnormal peristalsis. In view of the risk of strangulation, surgical reduction was performed under general anaesthesia. Castration was not performed at this time as the owners wished to continue breeding the horse. Anaesthesia and the immediate recovery period were uneventful, though oedema and seroma in the right testicle occurred postoperatively. The horse was discharged from the clinic two weeks after surgery. One week later the horse was presented again with a history of acute colic of 12 hours duration. The animal had received 600 mg intravenous flunixin meglumine (Finadyne Solution; Schering Plough Animal Health) twice a day, 12 g intramuscular noramidopyrine (Spasfortan; TVM) and an intravenous infusion of 10 litres of 0·9 per cent sodium chloride (Chlorure de sodium Aguettant; Laboratoire Aguettant) from the referring veterinary surgeon. A right inguinal hernia was diagnosed by transrectal palpation, and manual reduction was attempted under sedation with 140 mg xylazine intravenously (Rompun; Bayer) without success. Preoperative haematology revealed a leucocytosis with neutrophilia (89 per cent). Heart rate was 56 bpm and the horse’s weight had decreased to 465 kg. The horse was prepared for immediate surgery. Once installed in a padded induction box, it was sedated (one-anda-half hours after the first sedation) with 511 mg xylazine and 18·6 mg butorphanol (Torbugesic; Fort Dodge Animal Health) administered intravenously through a preplaced 14gauge jugular cannula (Angiocath 14G; Becton Dickinson). Five minutes later, anaesthesia was induced by intravenous administration of 1 g ketamine (Imalgene 1000; Merial) and 23 mg diazepam (Valium; Roche), which resulted in a smooth transition to left lateral recumbency. The trachea was intubated with a 26 mm cuffed endotracheal tube and the horse was hoisted to the operating table and positioned in dorsal recumbency. The endotracheal tube (V-PET-26; Cook) was connected to a large animal circle breathing system (VLM; Matrix), through which isoflurane (Aerrane; Baxter SA) vaporised in oxygen was delivered. The horse was initially allowed to breathe spontaneously, and mechanical ventilation was commenced (Respirator GT; Stephan) half-an-hour after induction. Monitoring (Propaq; Welshallyn Protocol) was routine, and included palpation of the pulse, observation of respiration and the colour of mucous membranes, capillary refill time, ocular signs, capnography, pulse oximetry, an electrocardiogram, and indirect and direct arterial blood pressure monitoring via a pressure transducer connected to a 20-gauge cannula (Insyte-w 20G; Becton Dickinson) placed in the left transverse facial artery. Arterial blood gases were measured one hour after induction of anaesthesia and again one and two hours later. The partial pressure of oxygen (PaO2) rose from 12·63 kPa (95 mmHg) to 14·76 kPa (111 mmHg), pH increased from 7·20 to 7·28, the partial pressure of carbon dioxide (PaCO2) decreased from 6·52 kPa (49 mmHg) to 5·85 kPa (44 mmHg), bicarbonate increased from 18·4 mmol/l to 20·4 mmol/l. Positive and expiratory pressure (PEEP) of 5 cm H2O was initiated to try to improve oxygenation one hour after induction. Surgery lasted for four-and-a-half hours and total anaesthesia time was four hours and 45 minutes. The pulse and electrocardiogram remained normal throughout the anaesthetic, and blood pressure was acceptable, with mean arterial pressure falling from 72 mmHg shortly after induction to a minimum of 67 mmHg shortly before surgery commenced, subsequently rising steadily to 85 mmHg without pharmacological intervention. Towards the end of the surgery, mean arterial blood pressure decreased to 64 mmHg, so dobutamine (Dobutamine Aguettant; Laboratoire Aguettant) was administered by intravenous infusion (1·25 μg/kg/ minute) for two minutes, with the result that blood pressure increased to 84 mmHg and remained good until the end of surgery. Hartmann’s solution was administered intravenously at 5 l/hour during the anaesthetic period. At the end of surgery, the horse was placed in right lateral recumbency in a padded recovery box. The silicone endotracheal tube was changed for a red rubber one and secured in place for recovery and oxygen insufflated at 15 l/minute. The horse attempted to stand up one hour after discontinuation of isoflurane. The attempt was very smooth and slow but unsuccessful, leaving the horse with the rear left leg in a ‘frog-leg’ position. The horse also became extremely vocal, which was interpreted as a sign of pain. A venous blood sample revealed a slight increase in creatinine kinase to 590 U/l. The horse was given 18·6 mg butorphanol, 600 mg flunixin meglumine, 5 mg detomidine (Domosedan; Pfizer Animal Health), 23 mg diazepam and 1 g ketamine, all intravenously, and was hoisted to the operating table, which was then moved to the radiography suite where coxofemoral dislocation was confirmed (Fig 1). The horse was euthanased and postmortem examination revealed left hip luxation with a chip fracture of the femoral head. The coxofemoral joint and femoral neck in horses are capable of withstanding considerable force (Matthew and Short Communications
Databáze: OpenAIRE
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