HERD HEALTH
PIH-50
pork industry
handbook
PURDUE UNIVERSITY • COOPERATIVE EXTENSION SERVICE • WEST LAFAYETTE, INDIANA
Atrophic Rhinitis
Authors
Barbara Straw, University of Nebraska
G. Michael Daniel, Sioux Center, Iowa
Reviewers
Peter and Brenda Blauwiekel, Fowler, Michigan
David J. Ellis, Michigan State University
Steven C. Henry, Abilene, Kansas
Ralph A. Vinson, Oneida, Illinois
Atrophic rhinitis (AR) is a widely prevalent, multifactorial disease of swine characterized by a degeneration and/or failure of growth of the nasal turbinate bones. Clinical signs include sneezing, nasal discharge or bleeding, and distortions of the snout.

The milder, nonprogressive form of AR is caused by a toxin-producing bacterium, Bordetella bronchiseptica. The more severe and progressive form is caused by the toxin-producing Pasteurella multocida bacterium, alone or in combination with other bacteria such as Bordetella bronchiseptica. The severity of the disease may be related to the age of the pig when infected, the dose of infectious organisms, the amount of toxin produced by the bacteria and environmental conditions. Although B. bronchiseptica and P. multocida have been demonstrated to cause AR, clinical disease cannot be attributed solely to infection with either one or both bacteria. Various environmental, management and husbandry factors contribute to the development of clinical disease. In some herds these bacteria are present, but outward signs of disease are not. In herds harboring B. bronchiseptica and P. multocida, there are periods from 2 months to 2 years or longer when no clinical evidence of disease exists.
Development of AR Caused by Bordetella bronchiseptica Infection
Bordetella bronchiseptica readily colonizes the lining of the respiratory tract. It commonly locates in the nasal passages and the tonsils. The most severe disease occurs in piglets that are infected during the first week of life. Disease is less severe in pigs that are a few weeks older; and by 9 weeks of age, pigs show almost no clinical signs after infection. In some cases,
damage from the initial infection persists until slaughter, but in many cases of pure B. bronchiseptica infection, damage to the nose begins to heal within 4 weeks after the onset of infection.

Development of AR Caused by Pasteurella multocida Infection
Toxin-producing strains of Pasteurella multocida have a poor capability for establishing themselves in a healthy nasal cavity. Experimentally, however, P. multocida readily colonize a nasal cavity that has been pretreated with chemical irritants or infected with B. bronchiseptica. Pasteurella multocida also infects tonsils and lungs. Similar to B. bronchiseptica infection, pigs infected with P. multocida at an earlier age may show more severe clinical signs. However, in contrast to B. bronchiseptica, P. multocida is capable of damaging the nasal cavity in pigs up to 16 weeks of age, and reversal of damage is less likely. In fact, the toxin produced by P. multocida has been shown to affect not only the structure of the nasal passages, but also to damage the liver, kidneys, ends of the long bones and certain components of the blood.
Sources of Infectious Agents
Infection in a herd most likely occurs after the introduction of infected breeding stock or feeder pigs, although other animals such as rodents, dogs and cats also may be carriers. Bacteria can be harbored in the nasal passages or tonsils of apparently healthy pigs.
Bacteria are spread from one pig to another through droplets in expired air. Litters in the farrowing house may be
Cooperative Extension Work in Agriculture and Home Economics, State of Indiana, Purdue University and U. S. Department of Agriculture Cooperating. H.A. Wadsworth, Director, West Lafayette, IN. Issued in furtherance of the Acts of May 8 and June 30, 1914. It is the policy of the Cooperative Extension Service of Purdue University that all persons shall have equal opportunity and access to our programs and facilities.