Anticoccidial drugs: Lesion scoring techniques in battery and floor-pen experiments with chickens

Although lesion scoring is a commonly accepted criterion for determining the pathogenicity of coccidial species, no previous attempt has been made to standardize and describe the scoring scale. In battery trials using pure species, the six species Eimeria tenella, E. necatrix, acervulina, E. mivati, E. maxima, and E. brunetti have been scored on a 0 to + 4 scale with descriptions of the gross pathologic changes for each score. Eimeria maxima and E. brunetti were found to be the most difficult species to score since the gross pathologic picture has been difficult to correlate with weight gains or other indications of pathogenicity. Birds from floor-pen trials infected with more than one species were also graded on a 0 to +4 scale. Four sections of the intestine (upper, middle, lower, and ceca) were each scored separately. No attempt was made to determine species, but microscopic examination of scrapings was made to confirm the presence of coccidia.