Etio-pathological studies on calf mortality with special reference to hepatic disorders in bovine calves
Abstract
The detailed postmortem examination of 52 carcasses of buffalo-calves and cow-calves was conducted from May, 2007 to February, 2008 received in the Department of Veterinary Pathology. Mortality was maximum in the age group of 1-3 months in buffalo-calves and of less than 1 month in cow-calves. The bacterial organisms isolated were E.coli (11 cases), Klebsiella pneumonae (5), Proteus mirabilis (4), Pseudomonas aeruginosa (3), Staphylococcus aureus (3), Corynebacterium pyogenes (3), Streptococcus pyogenes (2), and Citrobacter divergens (1). Various serotypes of E.coli isolates were O60, O20, O114, O164, O4 and O12. In six isolates, serotypes were untyped. In-vitro drug sensitivity and resistance against different organisms revealed that E.coli isolates were most sensitive to ceftriaxone + sulbactum and most resistant against oxytetracycline and streptomycin. 100% isolates of Proteus and Pseudomonas were sensitive to ceftazidime and gentamycin, respectively, Klebsiella
isolates to cefotaxime and furoxone, Corynebacterium isolates to ceftriaxone + sulbactum and kanamycin whereas Staphylococcus and Streptococcus isolates were 100% sensitive to the most of the antibiotics. Out of 19 E.coli isolates, 18 E.coli isolates possessed plasmids of molecular weights ranged from 4 to 20 Kb. The serotypes which were resistant to one or more than four antibiotics were found to possess plasmid of high molecular weight i.e. 20 Kb. The results of PCR revealed that 20 samples were found to be positive for E.coli as they gave an amplified product of 232bp. The examination of faecal samples collected from intestinal contents revealed two cases of Strongyles sp and three were of Eimeria sp. Gross and histopathological studies revealed that E.coli infected calves showed congestion and haemorrhages in various organs, hepatitis, serofibrinous pneumonia, catarrhal enteritis or haemorrhagic enteritis, focal interstitial nephritis, myocarditis and fibrinous pericarditis. Gram-negative red rod shaped bacilli were also demonstrated in hepatic and pneumonic lesions by Taylor’s stain. The characteristic lesions in Proteus infection were hepatitis, suppurative or fibrinous pneumonia, catarrhal or haemorrhagic enteritis, focal interstitial nephritis in kidneys, myocarditis and depletion of lymphocytes along with haemosiderosis. The characteristic lesions observed in Klebsiella pneumonae were suppurative bronchopneumonia, haemorrhagic enteritis or suppurative enteritis, mild fibrosis along with bile duct hyperplasia and fatty changes in liver and depletion of lymphocytes in spleen. Staphylococcus aureus infection was characterized by hepatitis with mild fibrosis in portal triad area in liver, acute interstitial pneumonia, haemorrhagic and catarrhal enteritis and acute interstitial nephritis. Streptococcus infection in calves was characterized by perivascular oedema in lungs, enteritis either haemorrhagic or catarrhal, pericarditis and suppurative myocarditis in heart and haemorrhages in liver and kidneys. Corynebacterium pyogenes infection was characterized by the presence of hepatitis and fibrous tissue proliferation in liver, bronchopneumonia, haemorrhagic enteritis and myocarditis. One case of cow-calf revealed tuberculosis granuloma in which red coloured coccobacilli were demonstrated by Ziehl Neelsen stain. Various mixed infections were also encountered like E.coli, Citrobacter divergens and Pseudomonas aeruginosa infection in buffalo-calf which was characterized by pyogranuloma in liver, serous pneumonia, catarrhal enteritis, fatty changes in myocardium, congestion and haemorrhages in kidneys. Another mixed infection was of E.coli and Pseudomonas aeruginosa, which was characterized by hepatitis, catarrhal enteritis, chronic myocarditis and interstitial nephritis. Mixed infection of Klebsiella pneumonae and Pseudomonas aeruginosa was characterized by thrombosis and hepatitis in liver, fibrinous pneumonia, mild myocarditis, catarrhal enteritis and congestion in kidneys. The results were also described on the basis of pathological conditions. Maximum cases observed were of haemorrhagic/catarrhal enteritis (37 cases) followed by hepatitis (35 cases), pneumonia (31 cases), myocarditis and pericarditis (14 cases) and interstitial nephritis (8 cases); nephrosis (5 cases)