Influence of experimental Eimeria zuernii infection in calves on electrolyte concentrations, acid-base balance and blood gases.

Coccidiosis, often caused by Eimeria zuernii, is an important disease in calf rearing and is clinically mainly associated with diarrhoea (PR Fitzgerald in Adv Vet Sci Comp Med, 24:121-143, 1980). Calves were experimentally infected with E. zuernii oocysts to investigate the effects of artificial E. zuernii coccidiosis on electrolyte concentrations, acid-base balance and blood gases. Therefore, animals were assigned to three groups: group 1 (n = 14) served as uninfected control group, group 2 (n = 11) was infected with 150,000 sporulated E. zuernii oocysts per calf, and group 3 (n = 16) was infected with 250,000 sporulated E. zuernii oocysts per calf. Aberrances which were attributed to coccidiosis were observed in the following parameters: sodium and chloride concentrations, pH (only high-dose infected group 3), base excess, standard bicarbonate, total carbon dioxide and partial pressure of carbon dioxide. Alterations were most pronounced in the high-dose infected group 3. Anion gap and oxygen saturation did not show significant differences between the groups. Due to diarrhoea and malabsorption in coccidiosis-affected calves, there is a distinct loss not only of fluid and blood but also of electrolytes and alkaline buffer substances which provokes the development of an acidosis. This is counteracted by metabolism and respiration but cannot be compensated in severely affected and moribund calves.