Lecture 26 4/29/25 Flashcards by Danika Boltz

Which location is most common for neoplasia in large animals?

cutaneous

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What are the characteristics of sarcoids?

-make up 20% of equine tumors and 90% of equine skin tumors
-fibroblastic tumor with epidermal and dermal portions
-behavior varies; can be indolent or locally aggressive
-do not metastasize

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What is the typical age distribution of sarcoids?

can occur at any age, but most common in young horses aged 3 to 6 years

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What is the signalment for sarcoids besides age?

-no breed or sex predilection
-occurs in donkeys, mules, and zebras in addition to horses

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What is the connection between BPV and sarcoids?

-most sarcoids have detectable BPV DNA and RNA
-typically BPV1, but can be BPV2 and BPV3
-control tissues from horses with sarcoids and normal horses are typically negative for BPV

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What are the forms of sarcoids?

-occult
-verrucous
-fibroblastic
-nodular
-mixed
-malevolent

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What are the proposed classifications for sarcoids?

indolent or invasive

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What are the characteristics of sarcoid behavior?

-some are static and can spontaneously regress
-others are locally aggressive
-tend to recur

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What are the most common sites for sarcoids on horses?

-head and ears (51%)
-limbs and shoulders (25%)
-neck, trunk, and genitalia (24%)

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How are sarcoids diagnosed?

*signalment, history, and clinical signs
-suggestive
*biopsy
-dermal and epidermal components
-fibroblastic whorls
-hyperkeratosis and acanthosis

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What are the common treatments for sarcoids?

-benign neglect
-excision +/- cryosurgery
-laser surgery
-immunomodulators
-intratumoral therapy
-electrochemotherapy
-acyclovir
-radiation
-combination therapy

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Why is it important to follow up on sarcoid cases?

recurrence rates range from 5 to 75%

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Which factors increase the risk of recurrence?

-size
-previous treatment

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Which factors influence the prognosis for sarcoids?

-type
-size
-site
-previous recurrence

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What are the characteristics of squamous cell carcinoma?

-tumor of squamous epithelial cells
-occur in all domestic species
-associated with lack of pigmentation
-appearance varies; generally ulcerative or proliferative
-second most common tumor in horses

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What are the possible sites of SCC?

-mucocutaneous sites around the eyes and genitals
-gastric/alimentary (horses, cattle)
-urinary bladder/tract (horses, cattle)

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What is the typical behavior of SCC?

-locally invasive, slow to metastasize
-recurrence is common

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Which horse breeds are predisposed to SCC?

-appaloosas
-paints
-belgians
-clydesdales
-shires
-haflingers

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Where does SCC most commonly occur in cattle?

ocular

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What are the characteristics of SCC in small ruminants?

-common in goats
-may accompany papillomas of udder and teats in goats
-may involve the ear and docked tails in sheep

What are possible causes of SCC?

-solar exposure/damage from UV radiation
-irritation
-papilloma virus

What are the genetics involved in SCC?

-missense variant of gene-damage specific to DNA binding protein 2
-recessive
-impairs ability to repair damaged DNA
-especially seen in haflingers, beglian drafts, rocky mountain horses

How is SCC diagnosed?

-signalment
-clinical signs
-biopsy

What are the treatment options for SCC?

*surgery plus adjunctive treatment
-cryosurgery or laser additive
*5-FU
-topical or intralesional
*antineoplastics
*radiation
*piroxicam
*hyperthermia
*immunomodulatory therapy

What are the characteristics of melanoma?

-seen in almost all species -horses are the most common large animal to develop melanoma

What are the characteristics of equine melanoma?

-primarily seen in gray horses -incidence increases with age -genes associated with increased risk include gray and agouti genes

What are the melanoma syndromes?

-melanocytic nevus; solitary and benign -dermal melanoma -dermal melanomatosis -anaplastic malignant melanoma

What are the possible locations of equine melanoma?

-perirectal is most common -parotid salivary gland is second most common -can occur internally

What are the characteristics of equine melanoma treatment?

-somewhat controversial; thought to make melanoma more aggressive -can be difficult depending on size and site

What are the treatment options for equine melanoma?

-excision -cryosurgery -laser surgery -cimetidine -autogenous vx -intralesional chemo. -radiation -piroxicam

What are the characteristics of the canine melanoma vx?

-safe in horses -stimulates immune response -may slow tumor growth and decrease tumor size

What are the characteristics of equine lymphosarcoma?

-most common neoplasia other than cutaneous -no breed or sex predilection -any age, but average is 6 to 10 years old

What are the possible classifications of equine lymphosarcoma?

-generalized or multicentric (most common) -intestinal/alimentary -mediastinal/thymic -cutaneous

What are the clinical signs of equine LSA?

-often vague -weight loss -fever -depression -colic -resp. signs -peripheral lymphadenopathy possible but uncommon

What is the clin path seen in equine LSA?

-typically normal lymphocyte counts; can lee lymphocytic leukemia -anemia -possible hypercalcemia -possible hyperfibrinogenemia -possible hyperglobulinemia -possible decreased IgM

What are the characteristics of equine LSA cell type?

-majority are T cell -can have T cell-rich B cell lymphomas

How is equine LSA diagnosed?

cytology and biopsy

What are the treatment options for equine LSA?

*extranodal solitary lesions -removal -radiotherapy *chemo -multiple protocols -some success, data limited *cutaneous -can try corticosteroids

What are the characteristics of bovine leukosis?

-any age; typically older than 2 years -no known breed or sex predilection -sporadic form is rare and not associated with BLV -adult lymphoma is most common and associated with BLV

What are the clinical signs of bovine leukosis?

-weight loss -peripheral lymphomegaly -signs dependent on site, including neurologic signs, cardiac signs, and/or hair loss

What are the possible etiologies of bovine leukosis?

-bovine leukemia virus -vertical or horizontal transmission -B cell transformation after virus infects cells

How is bovine leukosis diagnosed?

-clinical signs -persistent lymphocytosis -antibodies against BLV -cytology/biopsy

How is bovine leukosis controlled?

testing and removal of infected cattle

What are the characteristics of lymphosarcoma in camelids?

-can occur anywhere from 4 months to 15 years of age -weight loss common -palpable masses possible -lymph nodes, liver, kidneys, and lungs often involved -not associated with a retrovirus

What are the characteristics of lymphosarcoma in goats?

-accounts for about half of all neoplasia in goats -occurs between 2 and 18 years of age -no gender or breed predilection -multicentric lymphoma is most common

What are the characteristics of thymoma in goats?

-involves thymic epithelial cells +/- lymphocytes -3rd most common tumor in goats behind LSA and SCC

What are the signs of thymoma in goats?

-often subclinical -weight loss -anorexia -heart failure -megaesophagus -dyspnea -abomasal atony

What are the characteristics of hemangiosarcoma?

-variable behavior; may be based on age -can cause cutaneous or leg swelling and joint effusion in young animals -some young animals will have tumor regression -disseminated HSA can occur; often goes to resp. and MSK systems

What are other possible tumor types in large animals?

-renal adenocarcinoma in horses -uterine/ovarian tumors -granular cell tumors in horses