Understanding the Oral Health-Retrovirus Connection
Did you know there is a connection between oropharyngeal inflammation and retrovirus infection in cats? While an association has long been suspected, recently a large survey finally uncovered details of the relationship between oral disease and feline leukemia virus (FeLV) and/or feline immunodeficiency virus (FIV) infection.1
Veterinarians at veterinary clinics and animal shelters scored the oral health status of over 5,000 cats according to criteria presented in online training. Only cats with no known history of FIV vaccination were included. All cats were tested for FeLV and FIV. Overall, 4.6% of cats were seropositive for FIV and 3.6% were seropositive for FeLV, which is similar to other recent large studies. As we would guess, oral inflammatory disease was common: 21% of all cats had gingivitis, 11% had periodontitis, and 4% had stomatitis. But more importantly, retrovirus infection was more common in the cats with oropharyngeal inflammation than in the general population. Of the cats with stomatitis, 22% were seropositive for FeLV and/or FIV. As well, 19% of cats with periodontitis and 8% of cats with gingivitis were retrovirus positive. The study results showed that a cat with any inflammatory oral disease (stomatitis, gingivitis, periodontitis) was at increased risk of being FeLV positive compared to cats with healthy mouths. For FIV infection, it was specifically cats less than 10 years old with stomatitis or periodontal disease that were at increased risk compared to cats with healthy mouths.
Oral disease is a common finding in cats
We know that oral disease is common in cats and has an impact on overall health and welfare. In a survey of over 15,000 cats examined at veterinary practices in the United States, the most commonly reported disorders were dental calculus (24.2%) and gingivitis (13.1%).2 The classification of oral inflammation in cats has been undergoing change to standardize terminology. In 2009, the American Veterinary Dental College recommended the term oropharyngeal inflammation to refer to any type of oral inflammation, replacing terms such as gingivostomatitis.3 The type of inflammation is then further described according to location. For example, stomatitis is specifically used to describe widespread oral inflammation while other terms describe localized lesions, such as gingivitis or periodontitis.
Chronic gingivitis, shown in the image below, and stomatitis are among the most common oral conditions in cats. The persistent inflammation causes the mucosa and gingiva to appear hyperemic, proliferative, and sometimes ulcerative with a bright red cobblestone appearance. Inflammation in other areas of the mouth (faucitis, pharyngitis, or palatitis) may also be present. Clinical signs (drooling, halitosis, bleeding gingiva, decreased grooming, and oral sensitivity) may be mild or more severe and they may or may not be noticed by the owner. Unfortunately, severely affected cats may have difficulty eating due to oral pain, leading to decreased food intake and weight loss.
The specific diagnosis of the type of oral inflammation is based primarily on clinical signs. Histopathology is not usually necessary, although you may choose to perform a biopsy for any unusual findings (e.g., atypical lesions, asymmetric lesions with a particularly aggressive appearance) to rule out neoplasia. The most common histopathologic findings are simply typical of a nonspecific chronic inflammatory response.
The underlying causes of chronic oropharyngeal inflammation in the cat are unknown. Many organisms, including viruses and anaerobic bacteria, have been found in association with this inflammation, although cause and effect is often difficult to prove. One study of biopsy samples from 30 cats found a cell-mediated immune response, which is consistent with a viral infection.4 Feline calicivirus is the most commonly found infection, especially in cases of caudal stomatitis.5
Oropharyngeal inflammation and retrovirus infection
Historically, we have suspected that oropharyngeal inflammation may be common in cats with FeLV or FIV infection, although most studies have included only small numbers of cats. In particular, cats with FIV infection often suffer from chronic stomatitis.6 In one study in western Canada, stomatitis, gingivitis or periodontal disease was found in 40% of 58 FIV-infected cats, but in only 10% of 58 age- and sex-matched uninfected control cats.7 The problem is not confined to domestic cats: we know that lions infected with lion-specific strains of FIV also suffer from more oral inflammatory disease than uninfected lions.8 Having more than one infection seems to make the oral disease more severe. For example, stomatitis in FIV-infected cats is often more severe when those cats are also infected with calicivirus or FeLV.9
Steps to take today
Given the new findings based on over 5,000 cats, we should recommend FeLV and FIV testing for all cats with oral inflammatory disease. Knowing a cat’s true retrovirus status is important as the results may affect the cat’s prognosis and influence your treatment plans. To that end, choosing accurate screening tests and providing for appropriate confirmatory testing is the best practice. As always, care should be taken to disinfect all dental instruments to avoid accidentally transmitting these viruses between patients. Fortunately, FeLV and FIV are susceptible to all routinely used disinfectants and do not survive long in the environment so, with some common-sense practices, prevention of viral transmission in the veterinary hospital is easy.
“…a cat with any inflammatory oral disease (stomatitis, gingivitis, periodontitis) was at increased risk of being FeLV-positive compared to cats with healthy mouths.”
Susan Little, DVM, DABVP (Feline)
Dr. Little received her DVM from Ontario Veterinary College, University of Guelph, Ontario. She achieved specialty board certification in feline practice in 1997. Dr. Little is part owner of two feline-specialty practices in Ottawa. She serves on the board of the Winn Feline Foundation and is a feline medicine consultant for the Veterinary Information Network (VIN). In 2010, Dr. Little was the recipient of the Canadian Veterinary Medical Association Small Animal Practitioner Award.