Canine mammary tumours Flashcards
At what age do mammary tumours become high risk?
The tumor risk increases with age and becomes significant when dogs turn 7 or 8 years old and continues to increase until the age of 11 to 13 years
Dogs with malignant tumors have been found to be significantly older than dogs with benign tumors: mean age of dogs with malignant tumors is 9 to 11 years and 7 to 9 years with benign tumors
Which breeds are more susceptible?
In general, mammary tumors tend to be more common in the smaller breeds. Purebred dogs are more commonly affected; poodles, Chihuahuas, dachshunds, Yorkshire terriers, Maltese, and cocker spaniels are frequently listed as high-risk breeds in the small-breed category
some of the larger breeds are also at increased risk, including the English Springer spaniel, English setters, Brittany spaniels, German shepherds, Pointers, Dobermans, and Boxers
What non age/ breed risk factors are there for mammary tumours
Overweight during puberty
How do inflammatory mammary carcinomas appear?
Affected dogs may easily be misdiagnosed as having mastitis or severe dermatitis because, rather than presenting with discrete well-circumscribed tumors, the entire mammary chain may appear edematous, swollen, warm, and painful
most dogs with inflammatory carcinomas have distant metastatic disease and signs of systemic illness.
What is the minimum staging needed in mammary tumours?
CBC), serum biochemistry, three-view thoracic radiographs, and fine-needle aspiration (FNA) of regional lymph nodes, even if palpably normal. Abdominal ultrasound may be indicated in dogs with suspected regional lymph node involvement or changes on preoperative blood work suggesting tumor-related or non–tumor-related serum biochemistry changes. Even though osseous metaplasia occurs occasionally with mammary adenocarcinoma and the mammary glands are a common site for extraskeletal osteosarcoma, there has been no prognostic value found for serum alkaline phosphatase activity
Where do mammary tissues drain lymphatically?
Can drain to multiple nodes and contralateral nodes
Compare simple and complex tumours
Simple denotes that the neoplasm is composed of one cell type resembling either luminal epithelial cells or myoepithelial cells, whereas complex neoplasms are composed of two cell types, both luminal and myoepithelial cells
What is a carcinoma in situ?
Well-demarcated, noninfiltrative nodule(s) of closely packed cells arranged in irregular tubules or nests that have not extended through the basement membrane.
Loss of normal architecture, cell and nuclear polarity with anisocytosis, anisokaryosis, and increased numbers of mitotic figures
Outline osteosarcoma of mammary tissue
Osteosarcoma is the most common mesenchymal neoplasm of the canine mammary gland, and there is often a history of recent rapid growth of a mammary mass that might have been present for some time. A proliferation of cells varies from fusiform to stellate to ovoid, and there is an association with islands of tumor osteoid and/or bone formation. Mitoses are frequently found. Metastasis occurs via the hematogenous route, mainly to the lungs.
What affects prognosis?
Size of tumour (although this is not important if there is LN spread)
LN spread
WHO spread
How useful is a lumpectomy if the tumour is malignant?
Development of second mammary tumors is well documented and has been reported in over 70% of dogs with malignant mammary tumors following lumpectomy, although the impact of second mammary tumor development on survival is not clear
What are the recommendations for a single lump removal?
for dogs with a single mammary tumor of known or unknown histotype, surgical excision wide enough to completely remove the mammary gland tumor is adequate.
What adjuvant therapy can be given aside from sx
Chemotherapy - evidence for effect is weak
OVH - if protective only if done early. Lots of large tumours may not be hormone responsive. Not clear how effective this may be
Systemic treatment, including nonsteroidal antiinflammatory drugs (NSAIDs), with or without chemotherapy, was found to be effective in prolonging survival in dogs with inflammatory carcinomas according to two independent retrospective case serie
