This study describes the clinical and histopathological findings in dogs with mammary gland tumours, and compares the histopathological and clinical evidence consistent with progression from benign to malignant to human breast cancer epidemiology. Clinical and histopathological data on 90 female dogs with 236 tumours was included. Dogs with malignant tumours were significantly older than dogs with benign tumours (9.5 versus 8.5 years), P = 0.009. Malignant tumours were significantly larger than benign tumours (4.7 versus 2.1 cm), P = 0.0002. Sixty-six percent had more than one tumour, and evidence of histological progression was noted with increasing tumour size. Dogs with malignant tumours were significantly more likely to develop new primary tumours than dogs with benign tumours, P = 0.015. These findings suggest that canine mammary tumours progress from benign to malignant; malignant tumours may be the end stage of a histological continuum with clinical and histopathological similarities to human breast carcinogenesis.

Extraskeletal osteosarcomas (EOSs) are rare tumors that arise in various soft-tissue sites (e.g., gastrointestinal tract, subcutaneous tissue, spleen, liver, skin, kidney, urinary bladder, muscle, thyroid gland, eye, and mammary glands). Soft-tissue osteosarcomas (STOs) occur in older dogs with no sex predilection; beagles and rottweilers are at higher risk. Mammary gland osteosarcomas (MGOs) occur in older females; mixed-breed dogs, German shepherd dogs, and miniature poodles are at higher risk. The median survival time for cases with STO was 26 days, and the major cause of death was local recurrence (92%). The median survival time for cases with MGO was 90 days, and the major cause of death was pulmonary metastasis (62.5%).

Prostatic carcinoma occurs primarily in older castrated male dogs and is typically a fatal disease (most dogs die within few months after the initial diagnosis). Surgery, i.e., total prostatectomy, or radiation therapy is often not pursued due to risks of complications and a high rate of distant metastasis. Cyclooxygenase-2 (Cox-2) expression has been documented in several malignancies, including canine prostatic carcinoma. Cox-2 inhibition has been reported to have preventative effects on several human malignancies and has therapeutic effects on both laboratory and spontaneous tumour models. The purpose of this retrospective study was to evaluate Cox expression and the effects of Cox inhibitors on survival in dogs with prostatic carcinoma. 94.1 and 88.2% of the tumours expressed Cox-1 and Cox-2, respectively. Furthermore, dogs treated with Cox inhibitors (piroxicam or carprofen) lived significantly longer than untreated dogs, 6.9 versus 0.7 months (P < 0.0001), suggesting that Cox inhibitors may have an important role in canine prostate cancer therapy.

The purpose of this retrospective study was to compare Rottweilers diagnosed with osteosarcoma (OSA) with other breeds to determine whether Rottweilers experienced a more aggressive form of the disease. Two hundred and fifty-eight dogs were evaluated (102 clinical and 156 necropsy cases). In the necropsy population, Rottweilers had a younger mean age at death (7.3 versus 9 years, P = 0.006). There were no significant differences between Rottweilers and other breeds in age at diagnosis, median disease-free interval or survival time. However, Rottweilers were more likely to have metastasis to the brain (7 versus 0%, P = 0.03). These results suggest that OSA in Rottweilers may have a different biological behaviour, but this study did not confirm that these differences were associated with a worse outcome.

Age-specific risk of recurrent stroke for various risk factors, calculated independently, was estimated using the first year of data from the Lehigh Valley Stroke Register. The register is based on a population of more than one-half million. Among the risk factors examined, the highest overall risk of recurrent stroke, 41.4, occurred with a history of at least one transient ischemic attack (TIA). After myocardial infarction (MI), the relative risk of a recurrent stroke was 8.0, while with all other heart diseases combined it was 8.4. With diabetes, the relative risk of a recurrent stroke was 5.6; with hypertension, it was 4.5. The relative risk increased with age after TIA and MI, but not for other heart disease, diabetes, and hypertension, except in the 85+-year-old age group.