Necrotic rhinitis is an uncommon, sporadic disease of young pigs characterized by suppuration and necrosis of the snout, arising from wounds of the oral or nasal mucosa. Confusion exists in the literature because of the use of the misnomer “bullnose” to also describe atrophic rhinitis (see Respiratory Diseases of Pigs: Atrophic Rhinitis in Pigs).
Fusobacterium necrophorum is commonly isolated from the lesion and undoubtedly contributes to the disease, but other types of organisms are frequently present. They gain entry through damage to the roof of the mouth, often as a result of clipping the needle teeth too short or using blunt clippers.
Clinical Findings and Lesions
Signs include swelling and deformity of the face, occasionally hemorrhage, snuffling, sneezing, foul-smelling nasal discharge, sometimes involvement of the eyes with lacrimation and purulent discharge, loss of appetite, and emaciation. Generally, only 1–2 pigs in the herd are affected.
The facial swelling usually is hard, but incision reveals a mass of pinkish gray, foul-smelling necrotic tissue, or greenish gray tissue debris, depending on the age of the lesion. The nasal and facial bones become involved, and facial deformity may be marked.
Necrotic rhinitis is readily differentiated from atrophic rhinitis by the bulging type of facial distortion seen in the former. The character of the exudate and its location within the tissue of the snout or face are also distinctive of necrotic rhinitis.
Prevention and Treatment
Prevention is directed toward avoiding injuries to the mouth and snout, improving pig processing techniques, and improving sanitation. When the disease occurs repeatedly, needle teeth should be clipped carefully.
If the condition is advanced, treatment may not be advisable. Early surgical intervention and packing the cavity with sulfonamide or tincture of iodine may be useful. In young pigs, sulfamethazine given PO is of value.
Last full review/revision March 2012 by Scott A. Dee, DVM, MS, PhD, DACVM