Small Animal - Mammary Neoplasia Flashcards
What is the incidence of mammary tumours in dogs?
Common in female dogs
35-50% are malignant
Rare in male dogs and likely to be malignant
Which dog breeds are more predisposed to mammary tumours?
Poodles Spaniels English setters Pointers Maltese Yorkshire terriers Dachshunds Dobermans
What is the incidence of mammary disease in cats?
Less common
90% are malignant
What are common sites of mammary tumour metastasis?
Lymph nodes - common Lungs - common Liver kidney Bone Heart
What is the likely cause of mammary tumours?
Hormonal - 90% benign and 50% malignant canine tumours have oestrogen and progesterone receptors
What, apart from homonal, are other aetiological factors that affect mammary neoplasia?
Gene over-expression Gene under-expression Adhesion molecules VEGF Cox-2 Other factors
What are the risk factors for mammary tumours?
Increasing age - 9.5 years on average
Dogs obese early on in life
Progestagen treatment increases risk - benign in dogs, malignant in cats
Benign mammary tumours increase risk of malignancy 3 times
Intact status or bitches after 2.5 years of age
What is the usual clinical presentation of mammary tumours?
Owner noticed a mass
Incidental finding on physical examination
Occasionally signs referable to metastases
Why is it important to palpate all the mammary glands?
Masses may be variable in size
Multiple different masses may be found
Masses amy be in one or bothchains
What glands are canine mammary tumours most common in?
Caudal glands
What must also be palpated when mammary tumours present?
Axillary lymph nodes
Inguinal lymph nodes
Rectal may reveal enlarged sublumbar lymph nodes
What does inflammatory carcinoma present as?
Diffuse swelling rather than discrete mass Massive oedema Erythema Pain in multiple glands Rapidly progresses Highly metastatic Systemic illness
What tumour types can present as mammary tumours?
Benign - adenoma, fibro-adenoma, benign mesenchymal tumour, benign mixed tumour
Malignant - carcinoma (solid, tubular, papillary, anaplastic/inflammatory), sarcoma, carcinosarcoma
What are the differential diagnoses for mammary lumps?
Mastitis Galactostasis Galactorrhoea Mammary hyperplasia Cutaneous/subcutaneous tumour
What animals is mastitis more common in?
Post-partum bitches
When can mastitis occasionally occur?
After oestrus or falso pregnancy
Describe mastitis
Glands - firm, swollen, painful Pyrexia Depression Inappetance Puppy neglect
Describe mastitis treatment
If dehydrated - IV therapy
IV antibiotics until resolved - usually 7 days
Cephalosporins a good choice
Abscesses need to bedrained surgically
What is galactostasis?
Accumulation and stasis of milk within mammary gland in nursing bitches
Describe galactostasis
Glands - warm, firm, swollen and painful
Secretions not infected
Describe galactostasis treatment
Self resolving
Gradual weaning
Food reduction helps ease transition
What is galactorrhea?
Lactation that occurs when it is not associated with pregnancy and parturition
What does galactorrhea result from?
Increased prolactin secretion
Stimulated by falling progesterone levels in late dioestrus
What treatment is required for galactorrhea?
Usually self limiting
Doesn’t require treatment
Withholding food for 24 hours followed by fradual return helps reduce lactation
What is mammary hyperplasia most commonly seen in?
Young, entire female cats
2-4 weeks after oestrus
What prevents recurrence of mammary hyperplasia?
Neutering
Why do we carry out haematology and biochemistry for mammary tumours?
Make sure geriatric patients are safe to anaesthetise
What should radiography be used for with mammary tumours?
Check for metastases to lung and sublumbar LN
Chest and abdomen
What percent of dogs are lung and LN metastases present in?
25-50% with malignant tumours
What should be checked on ultrasound for enlargement with mammary tumours?
Liver
Spleen
Sublumbar LN
Inguinal LN
What are fine needle aspirations useful for?
Differentiating benign from malignant tumours
Differentiating mastitis from infalmmatory carcinoma
Investigating enlarged lymph nodes
When would you use a coagulogram with mammary tumours?
If suspecting inflammatory carcinoma
Describe surgical biopsies in mammary tumours
Usually excisional
Incisional for inflammatory carcinoma or other inoperable tumours
Which tumours should you send for pathology?
All tumours
Record site of each one
What does immunohistochemistry determine?
Presence of hormone receptors in tumour
What should never be used as a sole treatment for mammary tumours?
Medical treatment
What may chemotherapy be used as for dogs?
Adjunctive after surgery
What is the treatment of choice for all mammary tumours? Which types is it not?
Surgery
Except inflammatory carcinoma, those with distant metastases
What must all tumours be submittted for?
Pathology
How many pairs of mammary glands do cats and dogs have?
Dogs - 5
Cats - 4
Describe mammary glands
Compound
Tubuloalveolar
Apocrine
What is the vascular supply for the mammary glands?
Caudal superficial epigastric
Cranial superficial epigastric
Branches of internal thoracic
Describe drainage of the mammary glands in dogs
4 to 5 drain to inguinal LN
1 to 2 drain to axillary LN
3 can drain in either direction
Also variable connections between 3 and 4
Describe drainage of the mammary glands in cats
3 and 4 drain to inguinal LN
1 and 2 drain to axillary LN
What margins are needed with mammary tumours?
2-3cm skin margins
What should be excised if tumour is attached?
Underlying abdominal wall fascia
What should be done with crainal/caudal superficial epigastric vessels?
Ligate as they are encountered
What should be placed if there is extensive dead space?
Closed-suction drain
What surgery should be done with dogs? Cats?
Dogs - complete but not radical
Cats - unilateral mastectomy is minimum advised
What are the 5 options for mammary tumour surgery?
Lumpectomy Simple mastectomy Regional mastectomy Unilateral mastectomy Bilateral mastectomy
Describe a lumpectomy
Excision of a mass
Surrounding margin of grossly normal tissue
Use when mass is: small, encapsulated, non-invasive, gland periphery
May get milk or lymph leakage
Can have post-op inflammation
Describe a simple mastectomy
Excision of entire gland containing tumour
2cm margins
Used when tumour is >1cm
Used when tumour is in centre of the gland or involves majority of it
Less risk of milk leakage
Describe a regional mastectomy
Excision of involved and adjacent glands
2cm margins
Used for excision of multiple tumours in adjacent glands
Used if mass is ebtween two glands
Caudal two glands often excised together with inguinal lymph node
Axillary LN not excised with cranial glands unless specifically indicated
Describe a unilateral masectomy
Excision of tumours in the third gland
Multiple tuours in one mammary chain
Excise all tumours on one side
Quicker and easier than spearate masectomies
Careful, tension-free closure is essential
Describe a bilateral masectomy
Only when multiple masses in both chains
Excise both mammary chains and inguinal LNs
Skin clouse is difficult if performed in one surgery
Decreased risk of wound breakdown if perform two unilateral several weeks apart
What is important with mammary tumour surgery?
Pre-emptive multimodal analgesia
What are four complications with mammary tumour surgery?
Seroma
Wound breakdown/infection
Hindlimb oedema
Recurrence of tumour or metastatic spread
What factors affect the prognosis of mammary tumours in dogs?
Tumour size - 3cm 85% recurrence
Histologic type - sarcomas>carcinomas
Grade/differentiation - 90% mortality at 2 years if poorly differentiated, 24% mortality at 2 years if well differentiated
Lymphatic or vascular invasion - poorer prognosis
Lymph node involvement - 80% recurrence in present, 20% recurrence if not present
Distant metastases - poorer prognosis
Progesterone/oestrogen receptors - better prognosis
Fixation to tissue or ulceration - poorer prognosis
What factors affect the prognosis of mammary tumours in cats?
Tumour size - >3cm median survival <2cm median survival 3 years
Extent of surgery - 66% recurrence if perform local compared to radical masstectomy
Histologic grading - 42% mortality at 2 years well diffenertiated, 70% mortality at 2 years moderately differentiated, 100% mortality at 2 years poorly differentiated
What is not prognostic with mammary tumours?
Tumour site
Type of surgery in dogs
Number of tumours
OHE at time of excision
What are the survival times with various tumours in dogs?
Inflammatory carcinoma - 30 days
Malignant, incompletely excised - 75% mortality in less than a year
Malignant, completely excised no metastases - 1 to 2 years
Malignant, completely excised and metastasized - 5 months
Benign tumours - curative
What is the median survival time for malignant mammary tumours in cats?
Less than a year
What is mammary neoplasia almost completely preventable by?
Early spaying
