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What is the etiologic agent of bovine squamous papilloma/fibropapilloma?
Bovine Papillomavirus (1-6)
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How is bovine papillomavirus transmitted, and in what animals does it usually cause disease?
- direct contact, abrasions
- cattle <2 years old
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How does bovine papillomavirus appear grossly?
horny, dry, cauliflower-like warts on head, neck, shoulders, and dewlap +/- papillomas on teats/udders/genitalia
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What does bovine papillomavirus look like on histopath?
well differentiated keratinocytes forming papillary projections +/- fibrous core
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Describe the behavior and therapy for bovine papillomavirus.
benign; usually spontaneously resolve within 6 months, surgical excision for solitary papillomas in adults
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What is the etiology of bovine squamous cell carcinoma?
variable, chronic sunlight exposure of a white-faced animal
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What is the gross appearance of bovine SCC?
plaques early then becomes ulcerated mass later
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Describe the behavior of bovine SCC.
malignant, highly locally invasive with late metastasis
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What is the etiology of equine squamous papillomas?
equine papillomavirus
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How is equine papillomavirus transmitted?
fly bites (vector borne)
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Describe the incidence of cutaneous papillomatosis and aural plaques.
- both are caused by equine papillomavirus and raised masses on muzzle, legs, distal limbs, genitalia
- Cutaneous papillomatosis: horses < 3 yrs
- Aural plaques: older horses
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Describe the behavior of equine squamous papillomas.
- cutaneous papillomatosis: spontaneous regression in 1-6 months
- aural plaques: persist
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What is the etiology of equine SCC?
chronic sunlight exposure
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What is the incidence of equine SCC?
lightly pigmented breeds are predisposed, older horses
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Describe the gross appearance of equine SCC?
ulcerated mass, mucocutaneous junctions (esp. lightly pigmented)
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Describe the behavior of equine SCC.
malignant, highly locally invasive with late local lymph node metastasis
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What is the treatment for equine SCC?
surgical excision +/- cryotherapy, radiotherapy, chemotherapy
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What is the etiology of equine sarcoids?
bovine papillomavirus 1 or 2
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What is the incidence of equine sarcoids?
VERY COMMON in horses <6 years old (can happen at any age)
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What are the possible gross appearances of equine sarcoids? (4)
- verrucous- dry horny, sessile
- fibroblastic- granulation tissue-like
- combination of both
- occult- flat, looks like thick skin with rough surface
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What are the common locations of equine sarcoids? (5)
head, eyelids, ears, penile sheath, lower limb
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Describe the behavior of equine sarcoids.
locally invasive and destructive but DO NOT metastasize
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What is the therapy for equine sarcoids?
surgical excision +/- adjunct therapy
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What is the etiology of cutaneous melanoma in horses?
spontaneous
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What is the incidence of cutaneous melanoma in horses?
exceptionally common in older grey horses
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Describe the gross appearance of cutaneous melanoma in horses.
pigmented nodules on the perineum, under the tail, pinnae, periocular, distal limbs, prepuce
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Describe the behavior of equine cutaneous melanoma.
often benign at initial presentation but many will eventually metastasize and become malignant
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What is the therapy for equine cutaneous melanoma? (4)
surgical excision curative with early lesions, cryotherapy, local chemotherapy, immunotherapy
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What is the etiology of equine mast cell tumors?
spontaneous
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Describe the cytologic appearance of equine mast cell tumors.
well-differentiated mast cells with eosinophils
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What is the behavior of equine mast cell tumors?
generally benign
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What is the therapy for equine mast cell tumors?
surgical excision is usually curative
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What is the subtype of the majority of cutaneous lymphomas?
T cell-rich, B cell lymphomas (TCRBCL)
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Describe the behavior of equine cutaneous lymphoma.
guarded prognosis
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What is the etiology of equine eosinophilic nodular disease?
unknown, but suggestive of a hypersensitivity reaction
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What are the 3 indistinct presentations of equine eosinophilic nodular disease?
equine nodular eosinophilic granuloma, axillary nodular necrosis, unilateral papular dermatosis
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What differentials should you consider when you see ulcerative nodular lesion on the wither or dorsum of a horse? (4)
- nodular necrobiosis collagenolytic granuloma (eosinophilic nodular disease)
- mast cell tumor
- Habronemiasis
- pythium insidiosum
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What is the therapy for nodular necrobiosis collagenolytic granuloma (eosinophilic nodular disease)?
corticosteroids
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What is the etiology of equine cutaneous habronemiasis?
hypersensitivity reaction to aberrant larvae of the stomach worms, which are deposited by flies
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What is the gross appearance of cutaneous habronemiasis in horses?
"summer sores" at the medial canthus, glans penis, prepuce, distal limbs- ulcerated red brown mass-like lesions (looks like granulation tissue)
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Describe the histological appearance of cutaneous habronemiasis.
eosinophilic granulomatous inflammation and granulation tissue and nematode larvae
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What is the etiology of phycomycosis?
pythium insidiosum
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What is the incidence of phycomycosis?
subtropical regions- most common in horses exposed to bodies of stagnant water
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What is the gross presentation of equine phycomycosis?
ulcerated, proliferative masses with draining tract and contain necrotic casts ("leeches" or "kunkers")
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What is the histologic appearance of equine phycomycosis?
eosinophilic and granulomatous inflammation with granulation tissue and hyphae
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What is the therapy and prognosis for equine phycomycosis?
complete surgical excision;prognosis decline with size and duration of lesions
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What is the cause of exuberant granulation tissue in horses?
excessive deposition of granulation tissue, likely due to continued wound traction/ damage and/ or wound infection
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What is the incidence of proud flesh in horses?
very common after injury on the limbs
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What is the therapy for exuberant granulation tissues in horses?
surgical excision if possible
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