Effect of atrophic rhinitis on growth rate in Illinois swine herds

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Abstract
SUMMARY: Influence of atrophic rhinitis (ar) on mean daily weight gain (mdg) was studied in hogs randomly selected from 7 farrow-to-finish herds in Illinois. Herds were selected to obtain a wide range of clinical signs and lesions of the disease; thus, prevalence of clinical signs of ar in finishing hogs ranged from 0% to 20% among herds, and in hogs examined at slaughter the proportion of hogs with turbinate lesions ranged from 5% to 92%. None of the herds investigated had any obvious problems with pneumonia; nevertheless, hogs with moderate to severe pneumonic lesions were excluded from the study, to minimize any combined effect of ar and pneumonia. In 3 herds, mdg in ar-free pigs was 15% to 18% better than in pigs with severe ar lesions. Prevalence of clinical signs ranged from 5% to 20%, and of turbinate lesions, from 66% to 92%. In 4 herds in which mdg appeared to be unaffected by ar, prevalence of clinical signs of the disease ranged from 0% to 5%, and of turbinate lesions, from 5% to 74%. No consistent pattern of influence on ar lesions was found for bacterial infections, as determined by culturing of nasal swab specimens on MacConkey agar and blood agar.