Small Animal Mammary Gland Disease

Question 1

Incidence of mammary tumours in bitches?

Answer 1

Common
35-50% malignant
50% metastasise

Question 2

Incidence of mammary tumours in cats?

Answer 2

Less common
90% malignant
80% metastasise

Question 3

Causes of mammary tumours?

Answer 3

Hormonal influences likely

Canine:
Oestrogen and progesterone receptors found in 90% benign, 50% malignant and 0% metastatic

Feline:
Progesterone receptors

Question 4

Why are metastatic mammary tumours unlikely to respond to medical treatment?

Answer 4

Tumours tend not to well differentiate , so don’t have many receptors

Question 5

Risk factors for mammary tumours?

Answer 5

Increasing age
Entire bitch/queen
Obesity
Progesterone treatment
Benign tumours predisposing for malignant tumours

Question 6

PE of mammary tumours?

Answer 6

Wide variation in mass size/number/appearance

Palpate all glands

Inflammatory carcinoma = looks like hot mastitis

Feline tumours often not discrete masses

Palpate inguinal and axillary LNs

Rectal exam

Question 7

Benign mammary tumours?

Answer 7

Adenoma
Mesenchymal tumour
Mixed tumour

Question 8

Malignant mammary tumours?

Answer 8

Carinoma
Sarcoma
Carinosarcoma

Question 9

DDx for mammary masses in small animals?

Answer 9

Mastitis
Galactostasis
Galactorrhoea
Mammary hyperplasia (young cats)
Cutaneous/subcutaneous tumour

Question 10

Why is staging mammary tumours important?

Answer 10

Treatment plan
Prognosis
Baseline for ongoing evaluation

Question 11

How do you diagnose mammary tumours?

Answer 11

PE
FNA enlarged LNs
Haem, biochem, coagulation
Biopsy
Chest/abdominal radiographs
US abdomen

Question 12

What can an FNA be used for in mammary tumours?

Answer 12

Differentiate between mastitis and carcinoma
Rule out skin tumours
Benign or malignant