Factors influencing the incidence and prognosis of canine mammary tumours

Abstract

Factors relating to the incidence of canine mammary tumours are reviewed. Increased age, intact status or ovariectomy after 2.5 years of age, as well as progestagen treatment, can all lead to an increased risk of mammary neoplasia in the bitch. In addition, obesity early in life, and a habitual diet based on home‐made food (rich in beef and pork, and poor in chicken) as opposed to commercial food, are also associated with the occurrence of mammary tumours. Other aspects related to incidence are also discussed. Increased age at diagnosis, invasive growth (fixed to adjacent tissues), large tumour size, ulceration of skin, and axillary or inguinal node involvement are clinical parameters associated with a low chance of survival after surgical excision of mammary tumours. Histological typing and grading of the tumour allows the establishment of a prognosis, which is poor where there is tumour proliferation as measured by S‐phase fraction determination and Ki‐67 immunostaining.

Evaluation of clinical and pathological characteristics of 155 canines with mammary tumours: a retrospective study

“…This may be related to the fact that small or miniature dogs, especially poodles, are the dominant house-hold pets in this region compared to medium or large sized dogs. Therefore, we agree with the belief that breed predisposition varies due to the pet population (Alenza et al 2000).…”

“…At 9 to 11 years of age, dogs have maximum risk of developing mammary tumours (MTs) although the risk rises at the age of 6 to 7 years which is defined as the "cancer age" (Schneider 1970, Moulton 1990). Hormonal influences, obesity at a young age and intake of red-meat or home-made diet were determined to increase the risk of tumour development (Schneider et al 1969, Briggs 1980, Sonnenschein et al 1991, Bruun 1997, Alenza et al 1998, Alenza et al 2000. Factors like number of pregnancies, history of false pregnancies, regularity of oestrous cycles, number of litters or puppies and their size were found to be unrelated to the development of MTs (Brodey et al 1966, Schneider et al 1969, Schneider 1970.…”

Association of Obesity with Serum Leptin, Adiponectin, and Serotonin and Gut Microflora in Beagle Dogs

“…If pets weigh 20–30% more than their ideal body weight, they are classified as obese 1. Obesity in dog is associated with several health conditions including insulin resistance, pancreatitis, cruciate ligament rupture, and respiratory distress 2, 3. Bioactive peptides such as leptin, adiponectin, and pro‐inflammatory cytokines secreted from the adipose tissue are called adipokines 4.…”

A literature review on the welfare implications of gonadectomy of dogs

“…16,[19][20][21][22][23] The incidence of mammary gland neoplasia in dogs in the United States (3.4%) is significantly lower than that in other countries in which OHE is typically used only as a treatment of uterine diseases in older dogs. 19,21,[23][24][25][26][27][28] For instance, mammary gland neoplasia accounted for 70% of all cases of neoplasia evaluated in the municipality of Genoa, Italy, between 1985 and 2002, and the incidence of malignant mammary gland tumors in Norway was 53.3%. 21,23 Because 35% to 51% of mammary gland tumors of dogs are malignant, they represent the most common malignant tumors in dogs.…”

“…Age, hormonal exposure, and breed are the 3 main factors that contribute to the risk of developing mammary gland tumors, whereas diet, body weight, and obesity may play smaller roles. 19,24,30,33 Breed influences the incidence of mammary gland neoplasia. 16,21,25,29,30,34,35 These reports are supported by more recent breed-specific literature.…”