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**Metastases of the same in the bronchial and mediastinal lymph nodes
**Metastases of the same in the bronchial and mediastinal lymph nodes
*There is no serological test, and diagnosis depends upon raising the animal by the hind limbs whereupon a clear fluid issues from the nose = "Wheelbarrow test"
*There is no serological test, and diagnosis depends upon raising the animal by the hind limbs whereupon a clear fluid issues from the nose = "Wheelbarrow test"
<big>'''More information'''</big>
==Overview==
Etiology: Type B/D Retrovirus (also known as the jaagziekte retrovirus‑‑JSRV)
Condition: Pulmonary carcinomatosis.
Synonyms: Jaagsiekte, sheep pulmonary adenomatosis, ovine pulmonary carcinoma.
==General==
*Pulmonary carcinomatosis (OPC) is an infectious form of bronchioalveolar tumor with behavior of a low-grade carcinoma.
*Associated with (and strong evidence that is caused by) a type B/D retrovirus of family Retroviridae (single-stranded RNA).
*Occurs in Africa, Europe and the Americas.
*Susceptibility among breeds varies; Merino sheep are highly susceptible.
*The condition is considered to be a transmissible neoplasm with uncommon metastasis to regional lymph nodes and rare metastasis to other sites. Most growth is by local expansion and infiltration.
*The disease spreads via aerosol transmission and is less common in areas where the sheep are dispersed.
==Pathogenesis==
*The retrovirus associated with OPC is generally referred to as the jaagsiekte retrovirus (JSRV). This virus is morphologically distinct from all known retroviruses but has yet to be cultured.
*The target cells are type II alveolar epithelial cells and, less frequently, nonciliated bronchiolar epithelium.
*The virus-transformed epithelial cells proliferate, filling alveoli, spilling into adjacent airways and compressing and invading pulmonary parenchyma.
*The exact mechanism of carcinogenesis is unknown.
*Naturally occurring ovine pulmonary carcinomatosis has a long incubation period (months to up to 2 years), but experimentally, the time course of the disease can be reduced to a few weeks by inoculating lung tumor or lung fluid from affected sheep into neonatal lambs.
==Clinical Signs==
*Coughing
*Exercise intolerance (thus the Afrikaan name jaagsiekte, “driving sickness”).
*Crackles and wheezes.
*Abundant watery exudate which is discharged from the nose, especially when the head is lowered. The discharge is an important diagnostic clinical feature.
*Dyspnea.
==Findings==
===Gross Findings===
*Lung parenchymal masses ranging from 1 – 20 mm dia. gray-blue-white nodules (early) to large gray nodular and confluent masses (later). The larger masses often have fibrotic centers.
*The lungs are enlarged, heavy, and fail to collapse.
*Coexisting bronchopneumonia, verminous pneumonia, chronic progressive pneumonia, or combinations of the three.
*Right ventricular hypertrophy and dilation.
*Deaths result from heart failure, hypoxia or secondary bacterial pneumonias.
Laser Disc: 2395; 2396; 11702; 15547.
===Microscopic Findings===
*Multiple proliferative foci of cuboidal or columnar cells which line alveoli and form papillary projections into their lumina (i.e., adenomatous hyperplasia, adenomas and adenocarcinomas).
*In larger masses the pattern is obscured and fibroplasia often occurs in more disorganized and degenerative areas.
*Early or uncomplicated lesions may have little to no accumulation of inflammatory cells; however, there are usually low to moderate aggregations of alveolar macrophages in alveolar lumina.
==Ultrastructure==
Some cells have cytoplasmic lamellar bodies characteristic of alveolar type II epithelial cells; others have secretory granules and glycogen compatable with secretory bronchiolar epithelial (Clara) cell origin.
==Differential Diagnosis==
# Chronic progressive pneumonia (maedi - lentivirus) --lymphofollicular interstitial pneumonia (with little to no significant alveolar epithelial hyperplasia).
# Remember, bacterial bronchopneumonias and verminous pneumonias may be present in addition to OPC.
==Comparative Pathology==
*Human bronchio‑alveolar carcinoma shares many histologic and behavioral characteristics with OPC.
*Type D retroviruses have been implicated in caprine and ovine nasal adenocarcinomas.
==References==
1. Hecht SJ, Sharp JM, and Demartini JC: Retroviral Aetiopathogenesis of Ovine Pulmonary Carcinoma: A Critical Appraisal. Br Vet J (1996) 152:395-406.
2. Dungworth DL: The Respiratory System, In:Pathology of Domestic Animals, 4th edition, ed. Jubb KVF, Kennedy PC, and Palmer N, pp.690-2, Academic Press, San Diego, CA, 1993.
3. Fenner FJ, Gibbs EPJ, Murphy FA, Rott R, Studdert MJ, and White DO: Retroviridae, In: Veterinary Virology, 2nd edition, pp. 578-9, Academic Press, Inc., San Diego CA, 1993.
4. Kimberling CV: Diseases of Adult Sheep, In: Jensen and Swift’s Diseases of Sheep, 3rd edition, pp. 270-3, 1988.
Written and revised by GD Young, 1988; BH Williams, 1991; WD Fall, 1994; TO Johnson, 1999.