Dr. P

Canine mammary gland neoplasia

• most common tumor of intact female dogs, second most common tumor of female dogs overall

• most commonly adenomas or mixed w/presence of bone/cartilage (benign) or adenocarcinomas (malignant)

• risk factors:

  • hormonal: 0.5% chance of occurrence when spayed before 1st estrus cycle, no protective benefit of spay after 4th estrus cycle

  • obesity: increased malignancy when obese at young age (increased serum estrogen from adipose)

  • diet: intake of human food/red meat

  • breed: small breeds

  • BRCA1 & 2 mutations: inherited, English Springer Spaniels

Pathogenesis of canine mammary gland neoplasia

• 50% benign, 50% malignant - difficult to distinguish via cytology

  • carcinoma most common

    • inflammatory carcinoma when mammary gland is painful, edematous, & erythematous → poor prognosis

  • may see sarcomas arising from stem cells in mammary tissue

• estrogen & progesterone receptors more likely retained in benign tumors

Staging mammary gland neoplasias

• evaluation of surrounding tissue for presence of local LN involvement or metastatic Dz

• examine local LN (PE, FNA), do chest rads & AUS

Feline mammary tumors risk factors

• hormonal: 91% reduced risk with spay <6mos, no protective benefit with spay after 24mos

• breed: Siamese + Persians

• exogenous progestin exposure (can occur in males)

• lower hormone receptor positivity is consistent w/higher rate of malignancy & aggression

  • malignant tumors much more common than benign (80%)

Prognostic factors of feline mammary tumors

• tumor size

• LN status/metastasis

• breed: DSH better prognosis than purebreds

Equine mammary cancer

• very rare, most often malignant, 50% w/evidence of metastasis

Mammary neoplasia in rats

• occurs in large percentage of intact female rats, 80% benign (fibroadenoma)

• pituitary adenoma secreting prolactin can induce mammary neoplasai

Neoplasms of uterus

• leiomyoma - smooth mm., usually benign

  • leiomyosarcoma - rare, malignant

• lymphosarcoma - rare except in bovine, assoc. w/BLV infection, pts present w/clinical signs assoc. w/other locations of lymphoma

• endometrial adenocarcinoma - rare except in rabbit, malignant w/common metastasis

Endometrial hyperplasia

• endometriosis: explanted endometrial tissue to aberrant sites outside of uterus (usually serosal surfaces in peritoneum), severity varies w/menstrual cycle, Dz of primates

• endometrial polyps: benign pedunculated masses made of glands & stroma extending from endometrium, can impact fertility

Vaginal polyps

• benign proliferation of vaginal mucosa & underlying stroma

Vaginal mucosa hyperplasia

• estrogen generated proliferation of vaginal mucosa

• occurs in dogs

• ranges from small protrusion from ventral commissure to large round protrusion from vulva

• typically regress when source of estrogen removed if no damage occurs to vaginal mucosa

Vaginal leiomyomas

• benign neoplasia arising from smooth mm. under vaginal mucosa

Ovarian neoplasia types

• surface epithelial: cystadenomas, adenocarcinomas (primarily in canine)

• gonadal stroma: granulosa cell tumor (horses, dogs, cattle)

• germ cells: teratoma (all species)

• misc: hemangioma, leiomyoma (all species)

• metastatic (all species)

Granulosa theca cell tumors

• derived from granulosa cells of follicle ± accompanied by proliferating theca cells

• granulosa cells attempt to create follicular structures → cystic structures w/in neoplasm

• cause repro dysfunction & aggression

• honeycomb appearance on US

• equine: relatively common, assoc. w/ elevated AMH, inhibin, testosterone, progesterone, and/or estrogen

• canine: can cause E2 production → mimicking signs of estrus

Canine ovarian epithelial tumors

• arise from surface epi or invaginations

• benign: adenoma/cystadenoma

• malignant: cystadenocarcinoma

  • can implant on peritoneum + secrete fluid, cause carcinomatosis (50% metastatic rate)

  • often bilateral

Teratomas

• arise from germ cells that give rise to oocytes

• differentiate into tissue derived from 2/3 germ cell layers

• typically benign

Stillbirth

• delivery of fully formed dead neonate

Abortion

• expulsion of products of conception from uterus before fetus is viable

Mummification

• desiccation of dead fetus in utero

• bacteria cannot be present, intact CL must be present for fetus to be retained in uterus

• fetal skin must be mature enough to resist autolysis

• more common in multiparous species

Maceration

• fetal death in presence of in utero bacterial infection/inflammation

• causes endometritis or pyometra

• can lead to fetal emphysema w/clostridial bacteria

• bone resists process

Embryonic death

• fertilized ova dies → cytolysis in zona pellucida → resorption or discharge at next estrus

• 15-30% occurrence, most often due to lethal chromosomal abnormalities

Causes of abortion

• fetal causes: infectious, toxic, nutritional, genetic

• maternal causes: circulatory failure, anemia, pyrexia, endotoxemia

• Dx rate of causes often low, outbreaks easier to Dx

Infectious routes of abortion

• respiratory

• transvaginal (venereal or iatrogenic)

• oral

• vector-borne

Reasons for low Dx rates of abortion

• abortion results from an event that happened much earlier

• advanced autolysis makes lesion ID difficult

• placenta often unavailable for exam

• non-infectious causes often not detectable in fetal tissues

Sampling for abortion workup

• dam serum samples (paired)

• fixed, frozen, & fresh (if possible) placental tissue w/cotyledon & intercotyledonary space included

  • pathognomonic lesions uncommon

• whole fetus if possible (sent to Dx lab or on-farm necropsy)

  • for culture: placenta, stomach contents, lung, kidney, liver, thoracic fluid

  • histopath: placenta, brain, thymus, etc.

  • crown-rump length

Hydrops

• excessive fluid accumulation in allantois or amnion

  • hydroallantois usually due to inadequate # of caruncles

  • hydroamnios usually due to malformation of fetus (unable to swallow amniotic fluid)

Brucella spp.

• Gram - bacilli/coccobacilli, facultative intracellular aerobic

• species-specific

• transmitted via contact w/infected discharge/conception products, ingestion/via MM, or venereally

Pathogenesis of Brucella

• organism introduced → bacteremia → macrophage infection → systemic translocation → collection in hemilymphatic organs + reproductive organs

• sometimes can be cleared by immune system

Clinical signs of Brucella

• late term abortions

• epididymitis w/suppurative exudate + chronic infertility in males

• fibrinonecrotic placentitis w/intratrophoblastic bacteria

• fetal bronchopneumonia (ruminants)

• partial fetal maceration

Dx of Brucella

• isolation of organism from blood, semen, or necropsy tissues

  • may be false negative

• serology (Ab testing) - agglutination, milk ring, IFA, ELISA

Control of Brucella

• remove animal from breeding population (segregate or cull/euthanize)

  • animals can shed after spay/neuter or recrudesce after Abx treatment

• vax available in ruminants

• test & slaughter program in bovines

Mgmt of Brucella zoonosis

• minimize direct contact w/fluids, tissues, & conception products

• inform Dx lab of Ddx

• reportable in many states (canines)

• be careful administering bovine vaccine

Canine herpesvirus-1

• replication very temperature sensitive (diminishes at >102F)

  • more readily replicates in cooler tissues - resp & repro

  • neonates more susceptible due to low/poorly regulated body temp

• easily killed by standard disinfectants

CHV-1 transmission

• horizontal transmission in naive adults, causes minimal clinical signs (genital ulceration)

• transmission to puppies:

  • transplacental: abortion/stillborn or weak puppies that die early

  • oronasal (MM): from term - 1wk old

• if puppy survives, virus becomes latent in nervous system + lymphoid organs

CHV-1 pathogenesis

• viral replication in nasal mucosa, pharynx, & tonsils

• hematogenous dissemination via leukocytes

• localization in mononuclear phagocytic cells of LN + spleen

• causes multifocal hemorrhagic necrosis in adrenals, kidneys, lungs, spleen, & liver

  • only other Ddx is neonatal septicemia

Dx of CHV-1

• clinical presentation w/characteristic gross lesions

• detection of virus via IFA or PCR

  • bitches can be seropositive w/o shedding

Control of CHV-1

• no vax available

• Tx of puppies typically not efficacious

• maintain ambient body temp in puppies (incubators)

• infected bitches develop Ab after first litter, pass onto puppies