Clinical features and outcome of functional thyroid tumours in 70 dogs.

OBJECTIVE: To describe the clinical features and outcome of functional thyroid tumours in dogs. MATERIALS AND METHODS: Retrospective multi-institutional study of 70 dogs diagnosed with thyroid mass and concurrent hyperthyroidism. Clinical data regarding presentation, treatment, outcome and functional thyroid status were retrieved. RESULTS: Overall median survival of dogs with functional thyroid tumours was 35.1 months and 1- and 3-year survival rates were 83 and 49%, respectively. Median survival time was 72.6 months for dogs treated with surgical excision and 15.7 months for dogs that did not receive surgery. Of the 50 dogs treated by surgery and for which thyroid status was known following treatment, 64% developed hypothyroidism after surgery. Histopathologically confirmed metastasis was identified in 3% of dogs. CLINICAL SIGNIFICANCE: Dogs with functional thyroid tumours may survive a long time after surgical excision, although post-operative hypothyroidism is common.

Comparison of methods to determine primary tumour size in canine apocrine gland anal sac adenocarcinoma.

OBJECTIVES: To assess agreement between measurement of primary apocrine gland anal sac adenocarcinoma tumours using digital palpation, CT and formalin-fixed tissue and to look for associations with metastasis at presentation. MATERIALS AND METHODS: Retrospective study of different methods of measuring primary tumour size in histopathologically-confirmed canine apocrine gland anal sac adenocarcinoma. RESULTS: One hundred sixteen tumours from 107 dogs were included. There was moderate agreement between maximal dimension of the primary tumour measured by CT compared to formalin-fixed tissue and digital palpation. There was no significant difference in median maximum dimension between the measurement methods. Vascular invasion, CT stage, digital rectal examination stage and formalin-fixed tissue stage were significantly associated with metastasis at presentation, while mitotic index of the primary tumour was not. Dogs with tumours >2.5 cm (tumour-stage 2) were significantly more likely to present with metastatic disease. CLINICAL SIGNIFICANCE: In canine apocrine gland anal sac adenocarcinoma, primary tumour size, tumour-stage and vascular invasion are strong predictors of metastasis at presentation.

Diagnostic accuracy of contrast-enhanced computed tomography for assessment of mandibular and medial retropharyngeal lymph node metastasis in dogs with oral and nasal cancer.

The diagnostic accuracy of contrast-enhanced CT for detection of cervical lymph node metastasis in dogs is unknown. The purpose of this retrospective, observational, diagnostic accuracy study was to assess the efficacy of CT for detection of mandibular and medial retropharyngeal lymph node metastasis in dogs. Histopathology of dogs with cancer of the head, CT and bilateral mandibular and medial retropharyngeal lymphadenectomy was reviewed. A single radiologist measured lymph nodes to derive short axis width and long-short axis ratios. Two blinded radiologists separately assessed lymph node margins, attenuation and contrast enhancement and each provided a final subjective interpretation of each node site as benign or neoplastic. Where radiologists' opinions differed, a consensus was reached. Sensitivity, specificity and accuracy were calculated for mandibular and medial retropharyngeal sites. Agreement between radiologists was assessed. Fisher's exact test and the Kruskal-Wallis H-test were used to assess associations between variables. Forty-one primary tumours were recorded in 40 dogs. Metastasis to mandibular or retropharyngeal lymph nodes occurred in 16 out of 40 dogs (43/160 nodes). Agreement between radiologists was almost perfect for margination, attenuation and enhancement, strong for interpretation of mandibular lymph node metastasis, and weak for interpretation of medial retropharyngeal lymph node metastasis. Sensitivity of CT was 12.5% and 10.5%, specificity was 91.1% and 96.7%, and accuracy was 67.5% and 76.3% for mandibular and medial retropharyngeal lymph nodes respectively. No individual CT findings were predictive of nodal metastasis. Given the low sensitivity of CT, this modality cannot be relied upon alone for assessment of cervical lymph node metastasis in dogs.

Computed tomographic evaluation of elbow congruity during arthroscopy in a canine cadaveric model.

OBJECTIVE: To assess the effect of arthroscope insertion, using a carbon-fibre rod model, on humero-radial, humero-ulnar and radio-ulnar congruity, as assessed by computed tomography (CT). METHODS: Cadaveric Greyhound elbow joints were assessed at a flexion angle of 135 ± 5° using CT. For condition 1, a 36 mm fulcrum induced cubital valgus, as used to aid arthroscope insertion. For conditions 2 and 3, a single 1.8 or 2.5 mm diameter rod was inserted under arthroscopic guidance to simulate arthroscope position for assessment of the medial coronoid process. Repeat CT scans were obtained for all conditions and parasagittal sections were reconstructed to evaluate medial, axial and lateral positions within the elbow. Humero-radial, humero-ulnar, and radio-ulnar congruity measurements were obtained. Differences between groups were assessed using repeated measures analysis of variance. RESULTS: Mean (±SD) change in radio-ulnar step between conditions 1 and 3 was 0.6 ± 0.3 mm (axial), 0.8 ± 0.6 mm (medial), and 0.5 ± 0.1 mm (lateral). Insertion of rods induced a significant decrease in radio-ulnar step in all planes. Significant differences were also identified between groups for humero-radial, humero-ulnar, and radio-ulnar congruity. CLINICAL SIGNIFICANCE: Insertion of carbon-fibre rods as a model for elbow arthroscope insertion induces elbow incongruity. Changes in radio-ulnar congruity are small but the effect of arthroscope diameter should be considered when assessing elbow congruity.

In vivo femorotibial subluxation during weight-bearing and clinical outcome following tibial tuberosity advancement for cranial cruciate ligament insufficiency in dogs.

Ex vivo studies have been used extensively to investigate the mechanisms of tibial osteotomies but few have explored femorotibial alignment in vivo. The aim of this study was to assess femorotibial joint alignment under static weight-bearing conditions (and subsequent outcome) in dogs treated for cranial cruciate ligament (CrCL) insufficiency with tibial tuberosity advancement (TTA). Twenty-five dogs (30 stifles) with CrCL insufficiency treated by TTA were included. The distance from the origin to insertion of the CrCL (CrCLd) was measured on non-weight-bearing immediate post-operative radiographs and weight-bearing follow-up radiographs. CrCLd values were compared using a paired t test. The relationship between change in CrCLd (ΔCrCLd) and post-operative patellar tendon angle according to the common tangent method (PTACT) was assessed using Pearson's correlation. Outcome was assessed with an owner-completed questionnaire, and peak vertical force (PVF) and vertical impulse (VI) as percentages of bodyweight (BW). Following TTA, 21/30 stifles were persistently subluxated at a follow-up of 18 ± 14 months (mean ± SD). Follow-up weight-bearing CrCLd was greater (P<0.001) than post-operative non-weight-bearing CrCLd, with a mean ΔCrCLd of 5.8 ± 3.4mm (16 ± 10%). Post-operative PTACT was 89 ± 3° and did not correlate with ΔCrCLd (r=0.002, P=0.994). Mean PVF and VI were 65 ± 10% BW and 9±2% BW, respectively. All owners felt TTA provided improvement in lameness. The results indicated that TTA does not normalize sagittal plane femorotibial stability during standing at a PTACT of 90°, but most dogs return to good limb function regardless of femorotibial alignment.