Flexed radiographic angles for determination of atlantoaxial instability in dogs.

OBJECTIVE: To determine a flexed position for radiographic diagnosis of atlantoaxial instability (AAI) and to identify radiographic measurement cutoffs to differentiate affected dogs from neurologically healthy toy breeds. STUDY DESIGN: Retrospective case series and prospective case controls. ANIMALS: Thirty-nine client-owned toy breed dogs in which AAI had been diagnosed and 20 neurologically healthy client-owned toy breed dogs. METHODS: Medical records from three institutions were retrospectively reviewed to identify dogs affected with AAI. Flexed lateral images were reviewed, and measurements were obtained by using anatomic landmarks. Radiography was performed with control dogs to obtain the same measurements. RESULTS: Flexed lateral radiographs of thirty dogs affected with AAI were found to be positioned at a mean of 51° flexion. When flexed lateral radiographs were evaluated with a cutoff value for atlas to axis angle (AAA) >10°, evaluation of all breeds represented revealed a 90% sensitivity and 90% specificity. When this cutoff was evaluated in Yorkshire terriers, Chihuahuas, and mixes of these breeds, the sensitivity was 92%, and the specificity was 92%. When the control sample was positioned at 51° ± 10°, only two of the dogs were within the AAA cutoff value of >10°. There was no difference between the measurements obtained by using the flexed lateral view (mean = 50.9°) and the exaggerated flexed lateral view (mean = 38.9°) in the control sample. CONCLUSION: This study established objective measurements for the positioning and diagnosis of AAI on flexed lateral radiographs in toy breed dogs. CLINICAL SIGNIFICANCE: Atlantoaxial instability can be objectively diagnosed in sedated or anesthetized toy breed dogs when applying 51° flexion to cervical radiographs.

Surgical decompression, with or without adjunctive therapy, for palliative treatment of primary vertebral osteosarcoma in dogs.

Vertebral osteosarcoma (OSA) is the most common primary vertebral tumor in dogs, however studies examining the survival time after surgical decompression of these tumors are limited. There is also limited information regarding the benefit of adjunctive treatments such as radiation therapy or chemotherapy in these patients. The goal of this study was to determine survival time of dogs with primary vertebral OSA after palliative decompressive surgery alone and combined with radiation therapy and/or chemotherapy. Records from 22 client-owned dogs diagnosed with primary vertebral OSA and treated with decompressive surgery were collected retrospectively from eight referral institutions. Survival time was assessed for dogs treated with surgery alone as well as dogs who received adjunctive radiation therapy and/or chemotherapy. Median survival time in the 12 dogs treated with surgery alone was 42 days (range: 3-1333 days). The three dogs treated with surgery and chemotherapy had a median survival time of 82 days (range: 56-305 days). Only one dog was treated with surgery and radiation therapy; this dog survived 101 days. Six dogs were treated with surgery, radiation therapy and chemotherapy; these dogs had a median survival time of 261 days (range: 223-653 days). Cause of death in all cases that survived the initial postoperative period was euthanasia secondary to confirmed or suspected tumor regrowth. The results of this study suggest that definitive radiation therapy, possibly combined with concurrent chemotherapy, significantly improves survival in dogs treated with palliative decompressive surgery for vertebral OSA and should be the treatment of choice in selected cases.

Idiopathic generalised tremor syndrome in two cats.

Two male neutered domestic shorthair cats were evaluated for generalised tremors. On neurological examination both cats showed whole-body tremors, worsening with stress. A mainly cerebellar disorder was suspected. Blood examination, cerebrospinal fluid analysis and electrophysiological examination of both cats and magnetic resonance imaging of the brain in one cat were normal. Idiopathic generalised tremor syndrome (IGTS) was suspected owing to the exclusion of underlying causes and the clinical similarities with the syndrome in dogs. Treatment as recommended for dogs was initiated and resulted in improvement. This report describes the first cases of IGTS in cats.