PATHOLOGY OF RESPIRATORY DISEASES IN BOVINE CALVES
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Date
2016-07-25
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CSKHPKV, Palampur
Abstract
The present study was conducted to determine the prevalence and the factors responsible for respiratory diseases in bovine calves (sick-51, dead-40) of Himachal Pradesh. The nasal swabs and blood samples from sick and apparently healthy animals were collected from Palampur and its surrounding districts. The necropsy samples were collected from the postmortem received in the Department. Samples were collected from clinically sick and dead calves for bacteriological identification. Blood samples collected for TLC and DLC from calves exhibiting severe disease conditions revealed neutrophilia with increase in immature cells. Dead calves were subjected to necropsy examination and tissue samples were investigated at histopathology. Cytosmears prepared from nasal turbinate and affected portion of the lung revealed morphology of bacteria and the nature of exudate. In the present study, pneumonia was present in 31 (77.5%) of 40 calves and was considered an important contributor to death in 14(35%) of 40 calves whereas pneumonia associated with enteritis was observed in the remaining 17 (42.5%) calves. Out of 31 calves, 4 (12.9%) and 27 (87.1%) calves showed lesions suggestive of bronchopneumonia and interstitial pneumonia respectively. A few small white worms were observed in the upper respiratory tract in three cases, one with bronchopneumonia and two with interstitial pneumonia and the worms identified were Dictyocaulus viviparus. The most significant gross finding in the lung was hyperemia of the cranioventral region with pulmonary oedema. In 2 (6.45%) of 31 cases multifocal to coalescing abscesses were present in the cranioventral region. Mild rib impressions were also observed on the pleural surface of the lung in 13 (41.93%) cases with hazy appearance of the pleura in 24(77.4%) cases exhibiting both bronchopneumonia and interstitial pneumonia. The mediastinal and the bronchial lymph nodes showed gross changes of enlargement, oedema, hyperaemia and haemorrhage. On histopathological examination the turbinates showed mild inflammation in 27 (71.05%) out of 38 cases with infiltration of mononuclear (MNC) and polymorphonuclear (PMN) cells. Interstitial pneumonia was consistently characterized by the thickening of interalveolar septa due to MNC infiltration, hyperplasia of the bronchial and bronchiolar epithelium with peribronchial and peribronchiolar lymphoid proliferation. Clumping of macrophages was seen in nine cases with syncytia in one. In bronchopneumonia, the bronchioles and the alveolar lumen were filled with polymorphonuclear cells.Staphylococcusaureuswas isolated from the lungs showing subacute to chronic abscesses. Lymph nodes revealed mild to severe depletion of lymphocytes in the cortical region. E.coli, Streptococcus.sp, Staphylococcus.sp or Citrobacter.spwas common isolates from both upper as well as lower respiratory tract. Ciprofloxacin was found to be the most sensitive antibiotic followed by Gentamicin and Amoxycillin/Sulbactum. The present study revealed that pneumonia and pneumonia associated with enteritis are the common causes of calf mortality with its peak occurrence at six months of age.
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