Lecture 24 4/24/25 Flashcards by Danika Boltz

What are the mammary glands found in the dog?

M1: cranial thoracic
M2: caudal thoracic
M3: cranial abdominal
M4: caudal abdominal
M5: inguinal

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Which lymph nodes drain each mammary gland?

axillary: M1, M2, sometimes M3
superficial inguinal: M5, M4, sometimes M3

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What is the typical signalment for mammary tumors in dogs?

-middle aged to older female dogs
-small breeds

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What is the biologic behavior of mammary tumors in dogs?

50% are benign, 50% are malignant

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What are the characteristics of benign mammary neoplasms?

-typically adenomas
-cured with surgery

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What are the characteristics of malignant mammary neoplasms?

-often carcinomas or adenocarcinomas
-rarely sarcomas
-50% cured with surgery alone
50% behave aggressively

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Where do malignant mammary neoplasms metastasize to?

-lymph nodes
-lungs
-pleura
-peritoneum
-liver

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How does the timing of a dog spay impact risk for mammary tumors?

-spayed prior to first heat: 0.5% lifetime risk
-prior to second heat: 8% lifetime risk
-prior to third heat: 26% lifetime risk
-after third heat: no known risk reduction

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What are other risk factors for mammary tumors besides timing of spay in dogs?

-obesity; especially at one year of age
-age; older dogs more at risk
-genetics; links found in beagles, spaniels, and poodles

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What are the history and clinical signs of dogs with mammary tumors?

-lump(s) in the mammary chain
-often multiple lumps at time of diagnosis
-lumps most commonly in the M4 and M5 glands
-possible to have enlarged lymph nodes

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How are mammary neoplasms staged?

-MDB of CBC/chem/UA
-thoracic rads
-possibly abdominal ultrasound

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What are the characteristics of mammary tumor diagnosis?

*cytology:
-used to rule out other tumors
-can confirm if tumor is mammary in origin
-CANNOT determine malignancy of mammary tumors
*histopathology:
-gold standard for determining malignancy

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What are the prognostic factors for canine mammary tumors?

-tumor size
-metastasis
-tumor type/subtype
-complete surgical margins
-invasiveness
-ulceration
-hormone receptor reactivity

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What is NOT prognostic in canine mammary tumors?

-number of tumors
-type of surgery performed
-pregnancy

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What are the characteristics of surgery as a treatment for canine mammary tumors?

-treatment of choice
-want to palpate after shaving
-multiple tumors are common due to field effect
-want to remove with clean margins using simplest procedure possible

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What are the surgery technique options for mammary tumor removal in dogs?

-lumpectomy: used for small, superficial, non-fixed nodules
-mastectomy: removal of entire gland
-regional mastectomy: removal of glands 1-3 or 4-5
-radical chain mastectomy: removal of all mammary tissue on one or both sides

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What are the characteristics of lymph node removal for mammary tumor treatment?

-may be done to minimize tumor burden
-axillary lymph nodes are usually fixed and difficult to remove
-inguinal lymph nodes are easier to remove; should remove if enlarged or removing gland 5

What are the characteristics of spaying during mammary tumor surgery?

-not clear if there is an anti-tumor benefit
-does eliminate risk of uterine or ovarian d
-spay should be done before tumor removal

When should medical therapy be considered for mammary tumors?

-high grade
-vascular or lymphatic invasion
-lymph node or distant metastasis

What are the characteristics of NSAID use in canine mammary tumor patients?

COX-2 inhibitors prolong survival in dogs with high grade tumors or advanced stage dz

What are the characteristics of cytotoxic therapy as a mammary tumor treatment?

-standard of care in humans
-doxorubicin or carboplatin
-evidence of benefit in vet med is weak

When is palladia used in mammary tumor patients?

gross metastatic or inoperable dz

What are the characteristics of hormone therapy for mammary tumors?

-anti-estrogenic like tamoxifen is used
-used in humans with positive estrogen receptor activity
-not used in dogs; no known benefits and causes side effects

What are the characteristics of radiation therapy for mammary tumors?

-efficacy against microscopic dz unknown
-can be used in a palliative setting

What is the prognosis for canine mammary tumors?

-around 75% are cured with surgical removal -MST for dogs with high grade or metastatic mammary tumors is around a year -dogs can develop more tumors even following removal surgery

What are the characteristics of inflammatory mammary carcinoma in dogs?

-clinical diagnosis -aggressive and painful -looks like mastitis -carcinoma on biopsy -highly metastatic

What is the treatment and prognosis for inflammatory mammary carcinoma?

-focus on pain management +/- chemo -no surgery -can try radiation -MST around 1 to 2 months with palliative care and NSAIDs

What are the mammary gland pairs in the cat?

-cranial thoracic -caudal thoracic -cranial abdominal -caudal abdominal

What is the biologic behavior of feline mammary gland tumors?

-uncommon -90% are malignant; 90% of malignant tumors are metastatic -often carcinomas -need to do pre-op staging!

How does the age of spaying in cats reduce mammary tumor risk?

-less than 6 mo. old: 91% risk reduction -7 to 12 months: 86% risk reduction 12 to 24 months: 11% risk reduction older than 24 mo.: no benefit

Which cat breeds are at greater risk for mammary tumors?

-siamese/oriental breeds -possibly tri-colored DSH

What is the history and clinical presentation of cats with mammary tumors?

-50% present with multiple tumors -25% present with ulcerated tumors

What are the steps to staging for feline mammary tumors?

-always stage before surgery; very aggressive -CBC/chem/UA -cytology of any large lymph nodes -thoracic rads -abdominal ultrasound

What are the poor prognostic indicators for feline mammary tumors?

-tumors larger than 3cm in diameter -high grade -metastasis to lymph nodes or lungs

What are the positive prognostic indicators for feline mammary tumors?

-clean margins on surgery -younger age -DSH breeds

What are the characteristics of mammary tumor treatment in cats?

-must do staged bilateral chain mastectomy -decreased local recurrence leads to increased survival -want to submit entire specimen to check margins and get histopath. diagnosis

What are the characteristics of chemo and RT as treatments for feline mammary tumors?

*chemo: -indicated as adjuvant to surgery due to high metastatic rate -doxorubicin or carboplatin *palliative RT: -used for non-resectable dz

What is the prognosis for feline mammary tumors?

-guarded to poor with advanced dz -MST around a year with surgery -best prognosis with no negative prognostic indicators and tumors less than 2 cm in size

What are the characteristics of feline mammary fibroadenomatous dysplasia?

-rapid mammary tissue proliferation that is hormonally mediated -can be confused with mammary carcinoma -seen in young, intact, female cats -can be seen during pregnancy, 2 weeks post-estrus, or during progesterone treatment

What are the clinical signs of feline mammary fibroadenomatous dysplasia?

-firm, irregular masses -ulceration of masses -limb edema

What is the treatment for feline mammary fibroadenomatous dysplasia?

-spay -spontaneous regression -surgical removal of necrotic tissue