Measurement of the tibial plateau slope from lateral hind-limb radiographs is a preoperative requirement when performing tibial plateau leveling osteotomy (TPLO) for repair of the cruciate-deficient stifle in dogs. Two measurements of the tibial plateau slope in 312 stifles of 156 dogs were taken from lateral radiographs by each of three observers with varying degrees of experience in the measurement method. Intraobserver variability was +/-3.4 degrees, and interobserver variability was +/-4.8 degrees. No significant differences were identified for the intraobserver measurements; however, in evaluating interobserver variability, a significant difference was found between the inexperienced observer and the two experienced observers.

Two cats were presented for neurological dysfunction from suspected metronidazole toxicity. One cat was receiving 111 mg/kg body weight per day of metronidazole for 9 weeks. After 9 weeks, the dose was increased to 222 mg/kg body weight per day, and 2 days later the cat began to experience progressive neurological signs that culminated in generalized seizures. The second cat was receiving metronidazole at a total dose of 58 mg/kg body weight per day for 6 months. This cat experienced acute onset of ataxia and alteration in mentation. Laboratory evaluations in both cases were without significant findings. The neurological signs in both cats resolved within days of initiating supportive therapy and withdrawal of the drug. This report describes the two cases and discusses the etiology of metronidazole neurotoxicosis.

Polycythemia vera (PV) was diagnosed in a four-year-old domestic shorthair evaluated for hind-limb ataxia, extension of all claws, and difficulty in jumping to elevated surfaces. Mild cardiac hypertrophy also was diagnosed. Initial laboratory evaluation revealed polycythemia (packed cell volume [PCV], 75%) and normal serum total protein (7.5 g/dl). Definitive diagnosis of PV was reached by excluding causes of relative and secondary absolute polycythemia using radiography, ultrasonography, and blood gases, and by measuring serum erythropoietin concentration by radioimmunoassay (13 mU/ml) and an enzyme-linked immunosorbent assay (ELISA) method (8.0 mU/ml). Bone-marrow biopsy revealed relative erythroid hyperplasia characteristic of myeloproliferative disease. Clinical signs were controlled with hydroxyurea (12.2 mg/kg body weight) and occasional phlebotomy. Polycythemia vera is an uncommon feline disease, and clinical reports on the use of hydroxyurea to manage the condition in the cat are lacking.

OBJECTIVES To evaluate clonidine for preventing withdrawal from dexmedetomidine infusions and describe the incidence of withdrawal symptoms and adverse cardiovascular effects in critically ill pediatric patients. METHODS Retrospective, descriptive study of patients in Advocate Children's Hospital-Park Ridge PICU who received dexmedetomidine infusion for ≥72 hours, followed by clonidine for ≥48 hours, between January 1, 2015, and August 31, 2017. RESULTS Thirty-eight patients (median age 4.3 years; IQR, 2–11.5) received 39 dexmedetomidine courses. The median duration of dexmedetomidine exposure was 7.6 days (IQR, 5–11.5) at an average dose of 1 mcg/kg/hr. The median dose of clonidine at initiation was 8.3 mcg/kg/day (for <50 kg) and 4.1 mcg/kg/day (for ≥50 kg). The most common oral administration frequency was every 8 hours. Dexmedetomidine infusions for 7 days or longer and a higher dexmedetomidine dose 24 hours prior to clonidine transition both correlated with increased initial clonidine doses. Fourteen patients (37%) had at least 1 WAT-1 score of ≥3 during the transition between dexmedetomidine and clonidine, with 7 (18%) requiring an increase in sedation. Adverse cardiovascular events were possibly attributable to dexmedetomidine and/or clonidine in 4 patients. CONCLUSIONS Patients receiving prolonged infusions of dexmedetomidine may transition to clonidine to help prevent withdrawal symptoms. Duration of dexmedetomidine infusion of 7 days or longer and higher average dexmedetomidine dose 24 hours prior to the transition are important considerations when determining the initial clonidine dose. Transition from dexmedetomidine to clonidine was found to be safe and efficacious in our patients, with minimal adverse effects.

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