(Bottom image: turbinates of pigs with, from left to right respectively, mild to moderate to severe disease)
Atrophic rhinitis
Cause: Multifactorial – Bordetella bronchiseptica in association with toxigenic strains of Pasteurella multocida (type D). Crowding, inadequate ventilation, mixing and moving animals, and concurrent diseases intensify atrophic rhinitis.
Species: Swine
Signs: Two forms – nonprogressive atrophic rhinitis (due to B. bronchiseptica ) is mild, transient, and does not affect the animal’s growth and performance; progressive atrophic rhinitis (due to toxigenic P. multocida ), is severe, permanent, and associated with poor growth and feed conversion rates.
Acute onset, usually at ~3-8 weeks of age but can occur in any pig over 1 week old. Sneezing, coughing, inflammation of the lacrimal duct +/- tear staining, nasal hemorrhage. Turbinate atrophy +/- lateral deviation or shortening of the maxilla (some suffer turbinate atrophy with no apparent outward distortion). In early stages of infection, necropsy shows blanched mucosa with purulent material; in later cases, purulent material may be absent, but the nasal turbinates may be softened, grooved, or atrophied; the nasal septum may be deviated; and the surrounding bones may show asymmetric distortion.
Severity depends largely on the presence of toxigenic strains of P. multocida, how well the herd is managed, and the immune status of the herd
Transmission: Shed in nasal secretions of infected swine. Uninfected swine inhale infectious organisms, which colonize nasal passages. Symptoms are worsened by environmental (dust, ammonia) or other microbial irritation of turbinates. Though B. bronchiseptica also causes disease in other species, such as dogs, cats, and rats, those strains are not known to cause disease in pigs.
Diagnosis: Usually based on signs. Confirmation via cultures demonstrating the presence of toxigenic strains of P. multocida . Cultures are best performed early in the course of the disease. Routine monitoring is done in some breeding herds by measuring the degree of turbinate atrophy and giving the herd an atrophy score.
Treatment: Either cull the entire herd, disinfect facility, and restock with swine known to be free of atrophic rhinitis, or institute control measures below.
Prevention: Improve husbandry (better ventilation, improved hygiene and sanitation, less dusty feed), chemoprophylaxis (administration of ceftiofur, sulfonamides, tylosin, or tetracyclines to all sows, particularly before farrowing, and to newborn piglets. Medicated rations may be helpful. Efficacy of routine use of antimicrobials to control atrophic rhinitis in growing pigs is questionable), vaccination (vaccinate sows before farrowing, and young pigs at 1 and 4 wk of age), maintaining a closed herd. Monitor control progress via repeatedly examining the nasal passages of a substantial number of swine submitted for slaughter. Several systems for scoring the severity of lesions are available. Test replacement breeder animals and cull if positive.
Sources: Merck Veterinary Manual, Iowa State University College of Veterinary Medicine, NADIS (pig image), University of Illinois Veterinary Diagnostics Laboratory (image of nasal turbinates)
