Thymoma removal in a cat with acquired myasthenia gravis: a case report and literature review of anesthetic techniques.

UNLABELLED: HISTORY AND PRESENTATION: A 12 year old, 4.2 kg, domestic long hair, castrated male cat was presented with regurgitation, inability to retract the claws, general weakness, cervical ventroflexion and weight loss. A thymic mass was evident on radiographs. Acetylcholine receptor antibody titer was positive for acquired myasthenia gravis (MG). Thymectomy via midline sternotomy was scheduled. ANESTHETIC MANAGEMENT: Oxymorphone and atropine were administered subcutaneously as premedication, and anesthesia was induced with etomidate and diazepam given intravenously to effect. The cat's trachea was intubated and anesthesia was maintained with isoflurane in oxygen, and continuous infusions of remifentanil and ketamine. Epidural analgesia with preservative-free morphine was administered prior to surgery. Postoperative analgesia was provided by oxymorphone subcutaneously, interpleural bupivacaine, and fentanyl infusion. Postoperative complications included airway obstruction, hypoxemia and hypercapnia. FOLLOW-UP: The cat was discharged 3 days after surgery. Discharge medications included pyridostigmine and prednisone. Nine days after surgery, the cat had a significant increase in its activity level, and medications were discontinued. Histopathologically, the mass was consistent with a thymoma. Approximately 6 weeks later the cat became weak again and pyridostigmine and prednisone administration was resumed. CONCLUSION: The perioperative management of patients with MG for transsternal thymectomy is a complex task. The increased potential for respiratory compromise requires the anesthesiologist to be familiar with the underlying disease state, and the interaction of anesthetic and non-anesthetic drugs with MG. Careful monitoring of ventilation and oxygenation is indicated postoperatively.

Ultrasound-guided nerve blocks of the pelvic limb in dogs.

OBJECTIVES: To evaluate the efficacy of ultrasound-guidance in nerve blockade of the sciatic and saphenous nerves in dogs and to determine if this technique could allow lower anaesthetic doses to be used with predictable onset and duration of effect. STUDY DESIGN: Prospective randomized (for dose and leg) blinded experimental crossover trial with 10 day washout period. ANIMALS: Six healthy female Hound dogs aged 12.3 +/- 0.5 (mean +/- SD) months and weighing 18.7 +/- 0.8 (mean +/- SD) kg. METHODS: An ultrasound-guided, perineural injection was used with saline at 0.2 mL kg(-1) (Sal) or bupivacaine 0.5% at 0.05 (low dose; LD), 0.1 (medium dose; MD), or 0.2 (high dose; HD) mL kg(-1), divided 2/3 at the sciatic nerve and 1/3 at the saphenous nerve. Blocks were performed using dexmedetomidine sedation with atipamezole reversal immediately after completion of the injections. Motor/proprioceptive and sensory functions were scored using a 0-8 and a 0-2 scale, respectively. Clinically relevant blocks were defined as a motor score > or =2 and sensory score > or =1. Nonparametric methods were used for statistical analysis. RESULTS: No adverse effects were noted. There was a significant difference between the treatments with bupivacaine and the saline control, but not between the three bupivacaine treatments. Success rates of clinically relevant sciatic and saphenous blocks were both 67% (CI 95% 0.22-0.96). Onset and duration of the blocks were variable; 20-160 and 20-540 minutes, respectively. CONCLUSION AND CLINICAL RELEVANCE: None of the bupivacaine doses was significantly superior, though there was a tendency for a better block with the high bupivacaine dose. Either the technique or the doses used need further modification before this method will be useful in clinical practice.

Immobilization of red fox (Vulpes vulpes) with medetomidine-ketamine or medetomidine-midazolam and antagonism with atipamezole.

Thirty-two free-ranging red foxes (Vulpes vulpes) were immobilized with one of three combinations: medetomidine (0.076 +/- 0.017 mg/kg) and ketamine (2.1 +/- 0.5 mg/kg; MK, n = 16), medetomidine (0.057 +/- 0.008 mg/kg) and low-dose midazolam (0.6 +/- 0.1 mg/kg; MM-0.5, n = 10), or medetomidine (0.067 +/- 0.012 mg/kg) and high-dose midazolam (1.3 +/- 0.2 mg/kg; MM-1, n = 6) by i.m. injection. Induction and recovery times were recorded. Pulse, respiratory rate, body temperature, systolic and diastolic blood pressure, and oxygen saturation were measured. Anesthesia depth indicators were observed. There was a significant difference between the MM-0.5 and the MM-1 groups regarding induction time, 8.1 +/- 2.1 min and 5.0 +/- 1.7 min, respectively. The MK induction time was 6.9 +/- 2.5 min, which was not significantly different from the other two groups. All combinations provided effective immobilization for at least 20-25 min. During immobilization, there were significant differences regarding rectal temperature, which was higher in the MK group; and blood pressure, which was higher in the MM-1 group. After administration of atipamezole at 5 mg per 1 mg medetomidine given, there was a significant difference between the groups in recovery time; MK foxes were standing within 3.9 +/- 1.7 min, MM-0.5 foxes within 10.6 +/- 4.5 min, and MM-1 foxes within 10.2 +/- 3.4 min. None of the combinations caused rough or prolonged recoveries. Subjectively, the MM groups had smoother and less ataxic recoveries than the MK group. In conclusion, the authors recommend the use of medetomidine at 0.07 mg/kg in combination with midazolam at 0.8 mg/kg or ketamine at 2 mg/kg for the immobilization of free-ranging red foxes. During immobilization, monitoring of body temperature and oxygenation is recommended.

Computed tomographic analysis of calvarial hyperostosis in captive lions.

Osseous malformations in the skull and cervical vertebrae of lions in captivity are believed to be caused by hypovitaminosis A. These often lead to severe neurologic abnormalities and may result in death. We describe the characterization of these abnormalities based on computed tomography (CT). CT images of two affected and three healthy lions were compared with define the normal anatomy of the skull and cervical vertebrae and provide information regarding the aforementioned osseous malformations. Because bone structure is influenced by various factors other than the aforementioned disease, all values were divided by the skull width that was not affected. The calculated ratios were compared and the most pronounced abnormalities in the affected lions were, narrowing of the foramen magnum, thickening of the tentorium osseus cerebelli and thickening of the dorsal arch of the atlas. CT is useful for detection of the calvarial abnormalities in lions and may be useful in further defining this syndrome.

Field anesthesia of golden jackals (Canis aureus) with the use of medetomidine-ketamine or medetomidine-midazolam with atipamezole reversal.

Twenty-two free-ranging golden jackals (Canis aureus) were immobilized with a combination of 113 +/- 24 microg/kg medetomidine and 2.1 +/- 0.3 mg/kg ketamine (M-K) or 88 +/- 16 microg/kg medetomidine and 0.47 +/- 0.08 mg/ kg midazolam (M-M) by i.m. injection. Induction and recovery times were recorded. Pulse rate, respiratory rate, body temperature, systolic and diastolic blood pressures, and oxygen saturation were measured. Anesthesia depth indicators were observed. There was no significant difference between the M-K and the M-M groups regarding induction time (6:14 +/- 1:45 and 7:16 +/- 2:09 min, respectively). Both combinations provided safe and effective immobilization for at least 20-30 min. Pulse rate was significantly higher in the M-K group. There was no significant difference in any other objective or subjective parameter. Following administration of atipamezole at five times the dose of medetomidine given, there was a significant difference between the two combinations in recovery time; M-K jackals were standing within 3:42 +/- 2:17 min and M-M jackals within 8:47 +/- 4:32 min. Neither of the combinations caused rough or prolonged recovery. Subjectively, the M-M group had smoother and less ataxic recovery.

Sub-occipital craniectomy in a lion (Panthera leo) with occipital bone malformation and hypovitaminosis A.

Neurologic dysfunction accompanied by malformation of both the skull and the cervical vertebrae has been previously described in lions kept in captivity worldwide, and this dysfunction and malformation were most often related to vitamin A deficiency. Diagnosis of the bone malformation and its effects on the neural tissue was until recently limited to postmortem examination, with characteristic thickening of the bones of the cranial vault, cerebellar herniation, compression of the foramen magnum, and enlargement of the lateral ventricles. For some mildly affected lion cubs with neurologic signs, improvement was reported with excessive vitamin A supplementation. However, definitive diagnosis was only available for those that eventually died or were euthanized. This case documents the antemortem diagnosis of the disease using computed tomographic imaging and liver biopsy. While conservative treatment failed, suboccipital craniectomy removed the thickened occipital bone and was demonstrated to be a successful surgical intervention that can be used to treat more severely affected lions.

Treatment of thioacetamide-induced liver cirrhosis by the Ras antagonist, farnesylthiosalicylic acid.

BACKGROUND/AIMS: Several studies have indicated increased expression of the Ras protooncogenes in liver cirrhosis. In a previous study in rats, we have shown that a synthetic Ras antagonist, S-farnesylthiosalicylic acid (FTS), could inhibit the development of liver cirrhosis. The aim of the current study was to examine whether FTS will accelerate the resolution of liver cirrhosis induced in rats by thioacetamide. METHODS: Cirrhosis was induced in male Wistar rats by intraperitoneal (i.p.) administration of thioacetamide (200 mg/kg twice weekly for 12 weeks). In the treated group, the Ras antagonist FTS (5 mg/kg, i.p./3 times/week) was administered for 8 weeks after liver cirrhosis has already been established. Control cirrhotic rats received PBS injections for 8 weeks. RESULTS: Rats treated with FTS for 8 weeks had lower histopathologic score of fibrosis (P = 0.01), lower hepatic hydroxyproline levels (P = 0.0002) and lower spleen weight (P = 0.02) than the cirrhotic rats treated with PBS. Following FTS treatment, the MMP-2 and MMP-9-induced collagenolytic activity and TIMP-2 expression, were increased in FTS-compared to PBS-treated rats. TUNEL assay of liver sections performed 8 weeks after thioacetamide withdrawal showed increased apoptotic figures in both groups (P = NS). CONCLUSIONS: These results indicate that the Ras antagonist FTS accelerates the regression of experimentally-induced hepatic cirrhosis. The mechanism may involve increased collagenolytic activity.