A three-year-old weimaraner was presented with lethargy, anorexia, neck pain and a soft fluctuant swelling in the thoracic inlet. A cough had been noted previously. Clinical examination revealed tachycardia, tachypnoea, pallor and a large subcutaneous swelling, with bruising, suggestive of a haematoma in the thoracic inlet. Thoracic radiographs revealed a cranial mediastinal mass which had the ultrasonographic appearance of fluid, and there was also a marked generalised interstitial lung pattern. Routine haematology revealed severe anaemia and thrombocytopenia, although coagulation tests were within normal limits. A diagnosis of immune-mediated thrombocytopenia was however made on the basis of a positive antiplatelet antibody test and a rapid response to prednisolone therapy. Furthermore, a tentative diagnosis of Angiostrongylus vasorum infection was suggested on the basis of clinical and radiographic findings, although no lungworm larvae were identified on faecal analysis. Despite initiating treatment with fenbendazole, the dog died suddenly. Postmortem examination revealed myocarditis, thrombosing arteritis, pneumonia and chronic membranoproliferative glomerulonephritis associated with A vasorum infection.

This retrospective study describes 35 dogs with non-resectable, grade I-III mast cell tumours on the head or limb treated with prednisolone (40 mg m(-2) daily) for 10-14 days prior to radiotherapy (4 x 800 cGy fractions at 7-day intervals) from a 4 MV linear accelerator. Prednisolone was continued at a reduced dose rate (20 mg m(-2)) during radiotherapy and for 2 months or longer afterwards. Eighteen of 24 tumours (75%) decreased in size in response to prednisolone treatment. By 6-8 weeks following radiotherapy, 12 dogs had achieved a complete remission and 19 a partial response. Two tumours remained static and two progressed during the course of treatment. The overall response rate was 88.5%. With long-term follow-up, 11 dogs experienced local recurrence (n = 4), metastasis (n = 5) or both (n = 2). The median progression-free interval was 1031 days (95% CI 277.44-1784.56, Kaplan-Meier), with 1- and 2-year progression-free rates of 60 and 52%, respectively. Tumour grade did not predict the prognosis for this group of dogs, but tumour location did affect the outcome. Dogs with tumours located on the limb survived longer than those with tumours on the head. The combination of prednisolone with radiotherapy appears to have a useful role in the management of measurable mast cell tumours sited on the head and distal extremities.

Twenty-nine dogs were diagnosed with hyperadrenocorticism (HAC). A single determination of endogenous plasma adrenocorticotropic hormone (ACTH) and adrenal ultrasonography were used in a prospective study to differentiate between pituitary-dependent HAC (PDH) and adrenal-dependent HAC (ADH). In 27 out of the 29 dogs (93 per cent), both endogenous plasma ACTH concentrations and adrenal ultrasonography indicated the same cause of HAC. Twenty-one of the 29 cases (72 per cent) were shown to be pituitary-dependent; all had plasma ACTH concentrations of greater than 28 pg/ml (reference range 13 to 46 pg/ml) and both adrenal glands were ultrasonographically of similar size and of normal shape. All 21 cases responded well to mitotane therapy. Six cases (21 per cent) were shown to be adrenal-dependent; all had plasma ACTH concentrations below the limit of the assay (<5 pg/ml) and the presence of an adrenal mass on ultrasonography. The sensitivity and specificity of adrenal ultrasonography and endogenous ACTH determinations to identify the cause of HAC were demonstrated to be 100 per cent and 95 per cent, respectively, for ADH. These discriminatory tests are more accurate than published figures for dexamethasone suppression testing.

Three flat-coated retrievers with a regenerative anaemia were examined. They were hypoproteinaemic suggesting that the anaemia might be due to blood loss, but it was not possible to identify a site of haemorrhage. All three had splenomegaly with splenic abnormalities apparent on ultrasonography. Ultimately all three animals were shown to have a histiocytic sarcoma involving the spleen and other tissues. A fourth flat-coated retriever with anaemia, hypoproteinaemia and an abdominal mass was also diagnosed with a histiocytic sarcoma of the spleen following splenectomy. It is postulated that the dogs' anaemia was due to erythrophagocytosis, either directly by neoplastic cells or by reactive macrophages.