Exam 3 - Tumors of the Canine & Feline Mammary Gland Flashcards
how many mammary glands do dogs & cats have?
dogs - 5 pairs
cats - 4 pairs
what serves as lymphatic drainage for the mammary glands?
axillary lymph nodes & inguinal/sublumbar lymph nodes
T/F: age at the time of spaying has a direct effect on incidence of canine mammary tumors
true
incidence of mammary tumors in dogs increases with what?
age of the animal
what is the common age of dog that is affected by mammary tumors?
10 years
T/F: an intact female dog & a female dog that was spayed after her 2nd estrus have the same risk of developing a malignant mammary tumor
true - both 26%
what are some risk factors associated with canine mammary tumors?
larger breed dogs
spaniels, poodles, dachshunds
obesity at 1 year of age
what is the rule of 50 for dogs?
50% of mammary tumors are malignant
50% of mammary tumors are benign
50% of the malignant tumors will metastasize
most mammary tumors in dogs are what kind?
carcinomas
what are some canine mammary tumor types that provide poor histology?
sarcomas - hemangiosarcomas, osetosarcoma, fibrosarcoma
inflammatory carcinomas
ductal carcinomas
anaplastic carcinomas
what canine mammary tumor type is associated with edema, bruising, ulceration, and is very painful?
inflammatory carcinomas
what is the grading system used for canine mammary tumors?
grade 0 - in situ
grade 1 - lesions that invade the stroma but have no vessel invasion
grade 2 - vascular/lymphatic invasion and/or lymph node metastasis
grade 3 - pathologic evidence of distant metastasis
what is tumor grade based on in canine mammary tumors?
histologic differentiation
what is the typical patient presentation of mammary masses?
> 50% have multiple masses, and 65-70% of them are in glands 4 & 5
what does a benign mammary mass look & feel like?
small, well circumscribed, & firm
what does a malignant mammary mass look & feel like?
rapid growth, ill-defined, fixated to underlying tissue or skin, often ulcerated
what clinical signs are associated with inflammatory carcinomas?
multiple glands are affected, extends down the limbs or up the body wall, edema, erythematous, ulcerated, very painful, & mastitis is often more localized & seen after estrus
what tumor is this?
inflammatory carcinoma
what are some components of a good physical exam for a patient presenting with mammary masses?
palpate each & every gland, palpate regional lymph nodes, auscult lungs carefully, rectal exam, abdominal palpation
lameness or flat bone pain
what is the gold-standard for diagnosing a malignant mammary tumor? why not FNA?
histopathology is the gold standard
FNA can’t always differentiate between benign & malignant but can rule out non-neoplastic disease
what diagnostics & staging should be used in a dog with a mammary mass?
chem, cbc, & ua
chest rads
coagulation panel
FNA tumor
histopath
how is staging done in mammary tumors?
evaluate local lymph nodes - FNA & ultrasound
evaluate distant metastasis - ultrasound & thoracic radiographs
basic blood work - paraneoplastic syndromes & liver metastasis
when using rads/ct for staging, in regards to tumor size, lymph node metastasis, & distant metastasis, what is the staging of canine mammary cancer?
stage I - <3cm, no mets anywhere
stage II - 3-5cm, no mets anywhere
stage III - >5cm, no mets anywhere
stage IV - any size, lymph node mets
stage V - any size, mets or no mets in lymph nodes & distant mets
what are lumpectomies suitable for?
<0.5-1 cm masses - not for fixed tumors
what are mammectomies suitable for?
tumors >1cm or larger, fixed tumors, tumors centrally located in the gland, & must remove abdominal wall fascia & skin
what are regional mastectomies suitable for?
lymphatic connections between 1, 2, & 3
lymphatic connections between 3, 4, & 5
large tumors, tumors on the border of 2 glands, tumors with known poor histology, & multiple masses
T/F: unilateral/bilateral mastectomies are shown to increase survival times in dogs
false
what are unilateral/bilateral mastectomies suitable for?
multiple masses found throughout the mammary chains
when should lymph node resection be considered in dogs with mammary neoplasia?
only remove the axillary if enlarged
inguinal - remove with the 5th gland if enlarged
when is chemotherapy utilized for dogs with mammary neoplasia?
doxorubicin, cytoxan, 5-fluorouracil
stage IV/V, dogs with lymphatic invasion, & mitotic index > 9
what limits radiation therapy in mammary neoplasia in dogs? what can it be used for?
primary location of the cancer is what’s limiting
palliation of bone pain
why is OHE listed under therapy for mammary neoplasia in dogs?
won’t change the incidence of mammary neoplasia, but it may prevent other diseases, so SPAY FIRST!!
what is the median survival time for a mammary tumor < 3cm?
22 months
what is the median survival time for a mammary tumor 3-5 cm?
14 months
what is the median survival time for a mammary tumor > 5cm?
10 months
what is the median survival time of mammary neoplasia if the animal is positive for lymph node metastasis?
120 days
what is the median survival time of mammary neoplasia if the animal is negative for lymph node metastasis?
> 800 days
what is the median survival time of mammary neoplasia if the animal is positive for distant metastasis?
2-3 months
what is the median survival time of inflammatory carcinoma?
25 days with palliative care - recur within weeks after surgery
what is the 3rd most common tumor in the cat?
mammary tumors
what cats are predisposed to getting mammary tumors?
10-12 year olds, intact females
T/F: exogenous hormones increase risk of feline mammary tumors
true
how does early spaying protect a cat from getting mammary tumors?
OHE before 6 months of age - decreases risk by 91%
OHE before 1 year of age - decreases risk by 86%
what is the rule of 80 for feline mammary tumors?
> 80% are malignant
> 80% will metastasize
sarcomas & inflammatory carcinomas are rare while squamous cell
what condition can look like a tumor, occur in young cats after a silent estrus, or occur in any cat after exogenous progestin administration?
fibroepithelial hyperplasia
what condition is seen in this cat?
fibroepithelial hyperplasia
what is fibroepithelial hyperplasia?
condition that occurs in young cats after a silent estrus 1 or more glands, often bilateral, can become very large, erythematous, ulcerated, & edematous
why do an FNA on a suspected feline mammary tumor?
rule out mastitis or foreign body first - assume it’s malignant
what should be used for diagnostics & staging in feline mammary tumors?
cbc, chem, ua
chest rads, abdominal ultrasound
when using rads/ct for staging, in regards to tumor size, lymph node metastasis, & distant metastasis, what is the staging of feline mammary cancer?
stage I - <2cm, no mets anywhere
stage II - 2-3cm, no mets anywhere
stage III - 0-3cm, regional lymph nodes affected
stage IV - any size, mets or no mets in lymph nodes & distant mets
what therapy is recommended for feline mammary cancer?
surgery - for invasive tumors with early metastasis
staged unilateral mastectomies regardless of tumor size
OHE may help - good for fibroepithelial hyperplasia
why is chemo used for therapy of feline mammary cancer?
gross disease - short lived response to doxorubicin +/- cyclophosphamide
microscopic disease - adjuvant to surgery, overall increase in survival time
what is the prognosis of mammary tumors in cats?
guarded to poor in all cats - tumors can recur with conservative surgery
what is the median survival time of a feline mammary tumor that is > 3cm?
4-12 months
what is the median survival time of a feline mammary tumor that is 2-3 cm?
15-24 months
what is the median survival time of a feline mammary tumor that is < 3cm?
~ 3 years
what is the median survival time of feline mammary cancer using a staged bilateral mastectomy?
> 900 days
what is the median survival time of feline mammary cancer using a unilateral mastectomy?
~ 350 days
what is the median survival time of feline mammary cancer using a regional mastectomy?
> 400 days
what are transmissible venereal tumors?
naturally occurring horizontally transmitted tumor of dogs that has a worldwide distribution with coital transmission being common
where can TVT be located?
external genitalia, nasal cavity, oral cavity, subcutaneous tissues, & eyes
what is a risk factor of TVT?
immunosuppression
what is the latency period of TVT?
1-2 months
what is the suspected origin of TVT?
histiocytic origin
T/F: up to 17% of TVT can metastasize
true
how are TVTs transmitted?
directly from dog to dog
allograft
cellular mode of transmission - constant karyotype of 59 chromosomes
normal dogs have 78 chromosomes
what are the clinical signs of TVT?
common in intact sexually active male dogs living in an endemic area
discomfort/bleeding from genitalia
male dogs - glans penis
female dogs - caudal vagina or vestibule
how are TVTs staged?
local lymph node aspirates
good physical exam - especially of the face
cbc, chem, ua
how are TVTs diagnosed?
FNA, biopsy
look for round to oval nuclei, abundant pale cytoplasm, 1-2 nuclei, discrete clear vacuoles in cytoplasm
what tumor type is seen on this cytology?
TVT
what tumor is this?
TVT
what are the treatment options for TVT?
chemotherapy
radiation therapy
surgery
T/F: benign canine mammary tumors in situ & hyperplastic mammary tissues all have high estrogen receptors & progesterone receptors
true - steroid receptors decrease with malignancy
