GINGIVOSTOMATITIS IN FELINES: TREATMENT AND MANAGEMENT

Studies suggest these lesions occur as a result of an inappropriate immune reaction to chronic antigenic stimulation, with a shift from a normal type-one cellular response to a mixed type-one and type-two humoral response. The condition has a multifactorial aetiology, and there is a clear link between FCgS and the presence of bacterial dental plaque.

Feline calicivirus can be isolated from 97 per cent of cats with FCgS, but the incidence of feline leukaemia virus and feline immunodeficiency virus in affected cats is no greater than in the general population.

Cats testing positive for both calicivirus and feline immunodeficiency virus generally have a poor prognosis. Bartonella henselae has been implicated. This article will focus on the options available for the treatment and management of affected cats.

Dental hygien

Treating existing dental disease is crucial to the successful management of these cases. on initial presentation, cats should be examined under general anaesthesia and any teeth exhibiting resorptive lesions should be removed. Healthy teeth should be cleaned using an ultrasonic scaler and then polished with a fluoridated paste. radiographs should be taken, where possible to look for evidence of more subtle resorptive lesions and alveolar bone loss.

Severely affected cats may have proliferative and painful hyperplastic tissue in the fauces of the mouth. any tissue that interferes with eating, swallowing or the administration of medication should be resected with electrosurgery or a laser.

Care must be taken to avoid damaging tooth roots during gingival resection. Following dental attention, the client should be instructed on measures to improve the cat’s oral hygiene. Manually brushing the cat’s teeth daily is the most effective method, but this is often not practical and long-term compliance is poor. oral gels are of limited efficacy, although good results have been reported using a zinc ascorbate gel. Chlorhexidine mouth washes have also been of limited use.

The careful extraction of all cheek teeth and their roots carries the best prognosis, and should be considered in cases not responding to conservative treatment within four weeks. results vary, depending on the skill of the veterinary surgeon and aetio-pathogenesis of the disease in a particular individual. However, success rates of up to 80 per cent have been reported. In general, 50 to 60 per cent of cats do not require further treatment following the procedure; 30 to 40 per cent improve but may require medication intermittently and 10 per cent do not respond at all.

The procedure is not with-out risk, and surgery may be complicated by sclerotic and poorly vascularised bone, ankylosis of roots to the alveolar bone, the presence of resorptive lesions and fragile teeth. Iatrogenic damage to adjacent tissues, most notably the eye, has been reported. However, such complications can be minimised by careful technique and the use of appropriate instruments.

Prior to surgical extraction, the oral cavity and gingival sulci should be flushed with 0.12 per cent chlorhexidine gluconate and the teeth scaled to minimise debris in the mouth during surgery. The teeth and their roots are removed whole and an ostectomy/osteoplasty of the alveolar bone is performed. Following extractions, the mucogingival flaps should be closed using an absorbable suture material with a swagedon needle.

In exceptional circumstances, crown or coronal amputations may be considered as an alternative to complete extraction. In these cases, radiographic monitoring is required at regular intervals to ensure that the retained tooth roots are resorbing without incident.

Postoperative complications can be kept to a minimum by the pre-operative use of antibiotics and analgesics. Following surgery, analgesia may be achieved with buprenorphine (given parenterally or sublingually at a dose of 0.1mg/5kg bodyweight every six hours). alternatively, morphine or nSaIDs may be considered. Soft food should be fed for several days following surgery and, occasionally, a convalescent diet may be required for the first day or two. In severely affected cases, it may be prudent to place an oesophageal feeding tube.

Conservative treatment

Antibiotics remain one of the mainstays of conservative treatment used to reduce the numbers of anaerobic bacteria present in the oral cavity. recommended protocols include: clindamycin at 5mg/kg bid for six weeks; doxycycline at 20mg/kg sid for six weeks; or cefovecin at 8mg/kg by subcutaneous injection every two weeks for one to two doses. Metronidazole in combination with spiramycin has been used, but may be contraindicated in some cases due to its suppressant effect on cellmediated immunity. azithromycin at 10mg/kg sid for 21 days or rifampin at 10mg/kg sid for 21 days have also been used, but are not licensed in the UK.

Anti-inflammatories are usually required both for their anti-inflammatory and analgesic properties. The use of corticosteroids is controversial due to the high risk of diabetes mellitus development that is associated with longterm therapy. additionally, although cats may improve initially, there is often a “rebound” effect in which the clinical signs recur and deteriorate, despite treatment with increasingly higher doses of corticosteroids.

Prednisolone has been given at 2mg/kg to 4mg/kg daily and, occasionally, depot steroids are given intralesionally. Corticosteroids suppress both humoral and cell-mediated immunity and are clearly contraindicated in cats carrying calicivirus. With this in mind, cats displaying signs of gingivostomatitis should not be treated with corticosteroids until they have been tested for calicivirus.

Pain is an important consideration in these patients and nSaIDs have been used with some success, although their use should be reserved for cats with normal renal and hepatic function. Meloxicam can be given orally at a dose rate of 0.3mg/kg on day one of treatment and then 0.1mg/kg sid for between two and seven days. once clinical signs improve, the dose should be reduced to the minimum effective dose. Many cats will maintain on one to two drops per day. Ketofen at 1mg/kg sid for five days has been used with limited success. analgesia may also be obtained by administering buprenorphine orally at a dose of 10µg/kg.

Immunomodulatory drugs

Interferons belong to the cytokine family and have immunomodulatory and antiviral effects that are only partially understood. Feline recombinant interferon omega is now available in the UK and should be reserved for use in cats tested positive for calicivirus. The interferon must be stored in the fridge and will remain viable for up to 21 days when reconstituted. The solution can also be frozen for longer storage.

Results using feline recombinant interferon have been variable and a number of protocols exist for subcutaneous, subgingival and topical administration.

• Subcutaneous injections.

This is where 1MU (million units)/kg of the reconstituted solution is given every other day for five treatments. Provided the cat is responding, the frequency of dosing may be reduced to twice weekly. Treatment can be discontinued when the cat tests negative for calicivirus on three occasions at least one week apart. Other protocols give a second course of five injections one month following the first course if the cat has not responded adequately.

• Submucosal injections.

This is where 1MU are injected superficially under the mucosa in several sites around the lesions. The dose can be given on up to three occasions at 15-day intervals, and this requires a general anaesthetic.

• Topical “pulverisation”. This is where 0.1ml of reconstituted solution is diluted with 5ml of sterile saline. The remaining 0.9ml of the original solution can be divided into 0.1ml aliquots, frozen and stored for up to 90 days. Then, 0.5ml of the saline solution is sprayed over the lesions daily for 10 days, and the course is repeated at 10-day intervals on 10 occasions.

Other immunomodulatory treatments include thalidomide, which may shift the immune response from mixed to a more healthy cellular response – however, the drug can be difficult to obtain. The dose is 50mg to 100mg, which is given each evening. It should be noted that thalidomide is not licensed for cats and is strictly contraindicated in an entire female cat. Owners should be made aware of health and safety issues associated with the use of this drug.

Cimetidine has been recognised to stimulate the cellular immune response but studies of its efficacy in this condition are lacking. Bovine lactoferrin applied topically in the oral cavity (40mg/kg daily) has shown some benefit in cats suffering from FCGS associated with viral disease. Cyclosporine and aurothioglucose have both been used, but lack controlled trials and evidence supporting their use.

Diet and supplements

It is generally agreed that the consistency, shape and constituents of a cat’s diet can influence the development and progression of gingival disease, and specific dental diets are now available. Some vets advocate feeding a “natural” diet, but this must be balanced against the risk of nutritional imbalances. In the author’s experience, some affected cats improve on Sainsburys Applaws, Butchers Classic Cat Food, Hills A/D and Royal Canin Walthams Sensitivity Diet (other diets may also prove beneficial). Fibrous foods such as raw “skirt”, chicken wings and oxtail may be beneficial.

Other recommendations for management include using ceramic or metal food bowls, rather than plastic ones.

Antioxidants, such as vitamins A, C and E, and zinc, improve mucous membrane health and may exhibit antiviral and/or immunostimulant activities. Vitamin A can be given in the form of liver or fish oil for a maximum of six weeks, but longer courses may lead to the development of hypervitaminosis A.

It should also be noted that longterm use of vitamin C in cats can predispose the animal to oxalate crystalluria.

Suggested doses are: vitamin A at 200IU/kg/day to 400IU/kg/day; vitamin C at 125mg/cat/bid; vitamin E at 25IU/cat/bid to 75IU/cat/bid; and zinc at 7mg/cat/sid to 10mg/cat/sid.

Some vets advocate the application of slippery elm mixed with honey to the lesions. This herb is used widely by humans with inflammatory bowel disease and has been shown to have antioxidant effects on mucosae in vitro. Tablets are available, which contain 400mg slippery elm bark; 0.001ml cinnamon oil BP; 0.001ml clove oil BP; and 0.001ml peppermint oil BP. The recommended dose is half a tablet tid. There are no known contraindications.

Conservative treatment of FCGS centres around the use of a non-allergenic diet, restoring normal mouth flora and keeping plaque to a minimum. Antibiotics and analgesics are often required for extended periods of time and successful management of these cases relies on a dedicated client and a tractable patient. Cases failing to respond to simple oral hygiene measures should be considered for elective cheek teeth extraction at an early date and those testing positive for calicivirus may benefit from the use of interferon if extractions fail to result in an acceptable level of clinical improvement.