Jaagsiekte(zag-zi-ekte)

Ovine pulmonary Adenocarcinoma

Presented By: Sulove Koirala

Introduction

• A transmissible, retrovirus-induced neoplasia of sheep lungs

• Also called Driving Sickness

• Causative Agent: Jaagsiekte Sheep Retrovirus (JSRV)

• Spread by droplet infection from respiratory secretions.

• Rare in younger sheep, and is most common at 3-4 years of age

Clinical Signs• The incubation period in natural cases is 1-3 years

• Sharp sounds can be heard from the affected area

• Clinical signs are not noticeable until a significant proportion of the lung is affected by the tumor

• Unique feature: Overproduction of fluid in the lung that can be seen running from the nose when the animal lowers its head

Gross Lesions• Multiple, firm, raised, gray or white,

moist masses in the cranial and middle lung lobes

• Lungs are heavy, up to three times their normal weight

• Airways are filled with foamy secretion from the neoplastic cells.

Microscopic Lesions

• Well-differentiated bronchioloalveolar carcinoma.

• Within the neoplastic masses, the alveolar architecture remains, but alveoli are lined by cuboidal or columnar neoplastic epithelial cells.

• Proliferation of neoplastic cells results in papillary or acinar structures filling alveoli and obscuring their outline.

• Alveoli adjacent to the tumors are atelectatic and contain many macrophages, and interstitial fibrosis may be present in advanced cases.

Image Source:Jubb, Kennedy & PlamerPathology of Domestic Animals,2007(p 622)

PathophysiologyVirus Replicates in Type II pneumocyte in alveolus

Type II pneumocyte and Clara cells of bronchiole are transformed

Produces intra-alveolar and intra-bronchiole polypoid ingrowth

Contd…

The adenomatous ingrowths of alveolar epithelium encroach gradually upon alveolar space

Anoxia

Diagnosis

• At present, diagnosis of OPA relies on clinical and pathological investigations

• Wheel Barrow Test: One lifts the hind legs of the animal above the head to observe lung exudate flow out of its nose and mouth

• Polymerase chain reaction (PCR) offers hope for ante-mortem diagnosis of OPA as a flock test.

• Presence must be confirmed, at least once, by histopathological examination of affected lung tissue.

Recent Advances• Results suggest that JSRV-infected cells may be present in the

bone marrow of symptomless animals

• Jaagsiekte Sheep Retrovirus-Positive Cells are found in tissues of very young lambs fed naturally with colostrum from infected ewes.

ReferencesBorobia, M. D. (2012). Jaagsiekte Sheep Retrovirus-Positive Cells are Found in Tissues of Very Young Lambs Fed Naturally with Colostrum from Infected Ewes. Journal of Comparative Pathology, 146(1).

Borobia, M. D. (2014). Cells infected with Jaagsiekte sheep retrovirus are detected in the bone marrow of asymptomatic sheep. Canadian Journal of Veterinary Research, 78-80.

Jubb, Kennedy, & Palmer. (2007). Pathology of Domestic Animals. In Jubb, Kennedy, & Palmer, Pathology of Domestic Animals (pp. 621-622). Saunders Ltd.

Vegad, J. L. (2012). Textbook of veterinary special pathology. In J. L. Vegad, Textbook of veterinary special pathology (pp. 100-101). International Book Distributing Company.

Zachary, J. F. (2012). Pathologic Basis of Veterinary Diseases. In F. J. Zachary, Pathologic Basis of Veterinary Diseases (pp. 532-533). Elsevier Health Sciences.

Image Sourcehttp://www.cfsph.iastate.edu/DiseaseInfo/ImageDB/OPA/OPA_003.jpg

http://veterinaryrecord.bmj.com/content/168/15/393.2/F1.large.jpg

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