Pathophysiology of peste des petits ruminants in sheep (Dorper & Kajli) and goats (Boer & Beetal)

Peste des petits ruminants (PPR), an economically important viral transboundary disease of small ruminants is not only prevalent in Pakistan but also in other countries where people rely on agriculture and animal products. The present study was aimed at describing the pathology and antigen localization in natural PPR infections in local (Kajli sheep; Beetal goats) as well as imported small ruminant breeds (Dorper sheep; Australian Boer goat). Morbidity and mortality rates were significantly (P < 0.001) higher in indigenous Kajli sheep (75.37 and 32.80%) and Beetal goats (81.10 and 37.24%) as compared to Dorper sheep (6.99 and 1.48%) and Australian Boer goat (5.01 and 2.23%). Affected animals exhibited high fever, severe diarrhea, abdominal pain, respiratory distress and nodular lesions on lips and nostrils. Thick mucous discharge was oozing out from nostrils. On necropsy, lungs were congested and pneumonic, with nodular and cystic appearance. Intestines were hemorrhagic with zebra stripping. Characteristic histopathological lesions of PPR were noted in intestines, lymphoid organs and lungs. In GI tract, stunting and blunting of villi, necrotic enteritis, and infiltration of mononuclear cells in duodenum, jejunum and ileum. Small intestines exhibited diffuse edema of the submucosa along with proliferation of fibrocytes leading to thickened submucosa which has not been reported previously. Lymphoid organs showed partial to complete destruction of lymphoid follicles. Lesions of the respiratory tract included depictive of bronchopneumonia, severe congestion of trachea and apical lobe of lungs with deposition of fibrinous materials. Histopathological lesions of respiratory tract were severe and characteristic of broncho‐interstitial pneumonia, bronchopneumonia, interstitial pneumonia and fibrinous pneumonia. The alveoli were filled with edematous fluid mixed with fibrinous exudate, numerous alveolar macrophages, mononuclear cells along with thickened interalveolar septa and presence of intranuclear eosinophilic inclusion bodies. One-Step RT-PCR using NP3 and NP4 primers confirmed a PPR virus of 352 bp size in spleen, lungs and mesenteric and brachial lymph node samples. It was concluded that morbidity and mortality due to PPR were significantly higher in indigenous breeds of sheep and goat as compared to imported sheep and goat breeds. PPR has rendered various lesions in GI and respiratory tract which are characteristic in nature for the diagnosis of the disease under field condition.