Pipp
Well-Known Member
ah, well this is what's on my 'puter, and it's what Crystal already posted I think...
VIII. Rabbit (Shope) Fibroma Virus
A. Etiology: Fibroma virus is a member of the leporipoxvirus group and is closely related to myxoma virus. The virus has widespread incidence in both domestic and wild rabbit populations. Few cases of virus-induced fibromas have been diagnosed in rabbits in Missouri although the majority of cases are reported from the western and southwestern United States.
B. Transmission: The natural transmission cycle is not known although arthropod vector transmission is likely.
C. Clinical Signs: Tumors occur on the legs or feet, on the muzzle, and around the eyes. The tumors are subcutaneous and not attached to underlying tissue. Metastases from the original tumor do not occur. The infected adult rabbit remains clinically normal otherwise. Tumors will typically regress after a period of months. Spontaneous and experimental infections of neonatal domestic rabbits, however, has produced cutaneous and visceral tumors.
D. Pathology: The earliest lesion is slight thickening of the subcutaneous tissue followed by development of clearly demarcated soft tissue swellings which are evident on day 6 post inoculation. Tumors increase in size until day 12. They persist for months before regressing. The earliest microscopic lesion is an acute inflammatory reaction followed by localized fibroblastic proliferation. Proliferation continues until a distinct tumor is formed consisting of spindle-shaped and polygonal connective tissue cells with abundant cytoplasm. Intracytoplasmic inclusions are present in stellate cells, and less commonly or rarely in the epidermal cells. Degeneration of the epidermis overlying the tumor may result from pressure ischemia. This leads to necrosis and sloughing of the epithelium.
F. Diagnosis: Clinical signs and lesion morphology are primary diagnostic tools.
G. Control: This is not considered to be an important problem in domestic rabbits. In outdoor rabbitries, vector control is advised.
IX. Rabbit (Shope) Papilloma Virus
A. Etiology: A member of the papovavirus group. This disease is seen most frequently in cottontail rabbits of the Midwest with outbreaks in domestic rabbits. Incidence of disease is low.
B. Transmission: Arthropod vector transmission of the natural disease has been demonstrated. The mosquito is thought to be the main vector in transmission from feral to domestic rabbits.
C. Clinical Signs: Horny warts are found on the eyelids and ears. The growths are well keratinized, and the upper surface is irregular and split. The growths are easily scratched or knocked off. These sites later heal without complication.
D. Pathology: The tumor has the typical appearance of a papilloma with elongated rete pegs of epithelium surrounding central cores of connective tissue. A mild inflammatory cell infiltrate is normally found in the dermal layers underlying the tumor. Failure of the lesion to resolve may lead to development of squamous cell carcinoma.
E. Diagnosis: Clinical signs and histological examination are the basis for diagnosis.
F. Control: Control of the arthropod vectors will eliminate the introduction and spread of disease. Tumors that fail to spontaneously resolve in 30 days should be removed surgically to prevent dedifferentiation into neoplasia.
VIII. Rabbit (Shope) Fibroma Virus
A. Etiology: Fibroma virus is a member of the leporipoxvirus group and is closely related to myxoma virus. The virus has widespread incidence in both domestic and wild rabbit populations. Few cases of virus-induced fibromas have been diagnosed in rabbits in Missouri although the majority of cases are reported from the western and southwestern United States.
B. Transmission: The natural transmission cycle is not known although arthropod vector transmission is likely.
C. Clinical Signs: Tumors occur on the legs or feet, on the muzzle, and around the eyes. The tumors are subcutaneous and not attached to underlying tissue. Metastases from the original tumor do not occur. The infected adult rabbit remains clinically normal otherwise. Tumors will typically regress after a period of months. Spontaneous and experimental infections of neonatal domestic rabbits, however, has produced cutaneous and visceral tumors.
D. Pathology: The earliest lesion is slight thickening of the subcutaneous tissue followed by development of clearly demarcated soft tissue swellings which are evident on day 6 post inoculation. Tumors increase in size until day 12. They persist for months before regressing. The earliest microscopic lesion is an acute inflammatory reaction followed by localized fibroblastic proliferation. Proliferation continues until a distinct tumor is formed consisting of spindle-shaped and polygonal connective tissue cells with abundant cytoplasm. Intracytoplasmic inclusions are present in stellate cells, and less commonly or rarely in the epidermal cells. Degeneration of the epidermis overlying the tumor may result from pressure ischemia. This leads to necrosis and sloughing of the epithelium.
F. Diagnosis: Clinical signs and lesion morphology are primary diagnostic tools.
G. Control: This is not considered to be an important problem in domestic rabbits. In outdoor rabbitries, vector control is advised.
IX. Rabbit (Shope) Papilloma Virus
A. Etiology: A member of the papovavirus group. This disease is seen most frequently in cottontail rabbits of the Midwest with outbreaks in domestic rabbits. Incidence of disease is low.
B. Transmission: Arthropod vector transmission of the natural disease has been demonstrated. The mosquito is thought to be the main vector in transmission from feral to domestic rabbits.
C. Clinical Signs: Horny warts are found on the eyelids and ears. The growths are well keratinized, and the upper surface is irregular and split. The growths are easily scratched or knocked off. These sites later heal without complication.
D. Pathology: The tumor has the typical appearance of a papilloma with elongated rete pegs of epithelium surrounding central cores of connective tissue. A mild inflammatory cell infiltrate is normally found in the dermal layers underlying the tumor. Failure of the lesion to resolve may lead to development of squamous cell carcinoma.
E. Diagnosis: Clinical signs and histological examination are the basis for diagnosis.
F. Control: Control of the arthropod vectors will eliminate the introduction and spread of disease. Tumors that fail to spontaneously resolve in 30 days should be removed surgically to prevent dedifferentiation into neoplasia.
