Feline immunodeficiency virus (FIV) infection leads to increased incidence of feline odontoclastic resorptive lesions (FORL).

Feline odontoclastic resorptive lesions (FORL), previously known as 'neck lesions,' are commonly known in domestic, but also in non-domestic cats. They are characterized by odontoclastic resorptive processes, which take place at the dental root and at the periodontium. Chronic inflammation of gingiva and periodontium is believed to be an important etiological factor in the development of FORL. In this context, various feline viruses have been discussed to play a relevant role in the pathogenesis of these lesions. The aim of this project was to determine in a blinded study the incidence of FORL in 10 cats which were infected for several years with feline immunodeficiency virus (FIV), but were otherwise free of feline viral infections (feline leukemia virus, feline calicivirus, feline herpesvirus, feline parvovirus, feline coronavirus, feline syncytium-forming virus). Nine age-matched controls were kept under identical conditions, but free of FIV. Subgingival resorptive lesions were found in six of 10 FIV-positive cats, but in three of nine controls only. FIV-positive cats had significantly more often gingivae with an increased tendency for bleeding upon probing than FIV-negative cats (p=0.0055), and they had slightly more often hyperplastic gingivae (p=0.0867). In conclusion, signs characteristic of FORL such as subgingival lesions, granulomatous or hyperplastic gingivae with a tendency for bleeding, were found significantly more often in FIV-positive cats than in the controls (p=0.0198). Therefore, it was concluded that FIV infection is an important factor for the occurrence of FORL, possibly through immune suppression or changes of the (sub)gingival micro-environment. However, non-infected control cats also showed some evidence of FORL in the absence of all tested viral infections. Therefore, factors other than viral infections must also play a role in the development of FORL in cats.