Recherche Sur La Signification Pronostique Des Variations De La Zincemie Au Cours D'Une Pneumonie Experimentale A Pasteurella Haemolytica Al Chez Le Veau

Abstract

14 calves of the same breed and age were inoculated with a Pasteurella haemolytica Al (Phal) isolate as described in a previously published protocol. From the onset of the disease, 5 received an antibiotic treatment, 5 others a treatment combining the same antibiotic with a steroidal anti-inflammatory drug while 4 animals did not receive any treatment. A clinical examination was carried out twice a day to determine a mean disease score (MDS). After death or sacrifice the lungs were weighed, the extent of the lesions quantified in a score (mean lung score = MLS) based on combined inspection and palpation. A blood sample was taken each day from each calf with the usual precautions, and the plasma zinc content determined by atomic absorption spectrophotometry. The observations were made over a period of 8 days. 88 zinc determinations were performed. The analysis of variance showed a significant difference (p ≤ 0,01) between the plasma zinc content of calves considered to be clinically normal (MDS < 1,5) and diseased calves (MDS > 1,5), also a significant difference (p ≤ 0,01) between the plasma zinc contents of calves in which MOS < 1,5 + MLS < 1,5 and those in which MDS > 1,5 + MLS > 1,5. The correlation coefficient between terminal zinc levels and lung score (p ≤ 0,01) and between terminal zinc levels and lung weight (p ≤ 0,05) in animals in which the plasma zinc content before death or sacrifice was < 0,96 mg/I, was also significant. These linkages were not apparent in animals with normal plasma zinc levels. In our respiratory disease model these results confirm the linkage between zinc content and the inflammatory reaction brought about by intratracheal inoculation with Phal. They also demonstrate a relationship between hypozincaemia and pulmonary lesions. They therefore have a certain prognosis value. For these different reasons the plasma zinc content could serve as an indicator and provide information about bovine respiratory disease complex evolution.

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