Indolent lip ulcers in cats

• Indolent ulcer: on the upper lip. An ulcer with raised edges that is not usually painful or itchy.
• Eosinophilic plaque: on the abdomen and inner thighs. Red, weeping patches with intense itching.
• Eosinophilic granuloma: on the backs of the thighs as a line, under the chin and in the mouth. Lumps or firm bands, and swelling of the chin.

A cat can have several forms at the same time.

The name of the complex does not mean three different infectious diseases. These are recognisable reaction patterns of the skin or mucous membranes that may share an underlying cause. Eosinophils are often found in allergic inflammation, but their presence alone does not identify the allergen.

Here, indolent means an ulcer that typically causes few symptoms. It does not mean that all lip sores are harmless or that the lesion cannot expand. A very itchy abdominal plaque and an almost unnoticeable lip lesion in the same cat may therefore need a combined assessment.

Squamous cell carcinoma of the lip or nose, particularly in older and pale-coloured cats, can look similar. Your vet therefore takes a tissue sample, or biopsy, if the ulcer does not heal despite treatment or develops in an older cat. Infections, such as herpesvirus and fungal infections, and injuries are also ruled out.

The need for a biopsy is not assessed solely by age. A rapidly developing, tissue-damaging, unusual or persistent lesion despite treatment may also need a biopsy in a younger cat. A one-sided lip ulcer is among the situations in which your vet considers other oral diseases. Even a typical-looking ulcer is not a reason to use old creams without assessment.

• Examination and an impression cell sample from the ulcer to look for eosinophils.
• A biopsy if the finding is unusual or healing does not occur.
• Thorough flea treatment of all animals in the household under veterinary guidance as part of the investigation.
• An elimination diet for at least 8 weeks if food allergy is suspected. Blood tests for “food allergy” are not reliable for diagnosis.

At the appointment, your vet examines the rest of the skin as well as the mouth and establishes the history of itching, ulcers and previous treatments. Mention flea protection, skin products used and the whole diet, including treats. Concurrent changes can help identify a shared trigger.

A cell sample is assessed for inflammatory cells and possible bacteria or yeast. If infection is suspected or the lesion does not heal as expected, culture and drug susceptibility testing can help select treatment. The significance of bacteria is assessed alongside inflammation and the condition of the ulcer; not every lip ulcer needs the same antimicrobial treatment.

A biopsy examines tissue structure as well as cells. Sampling may be performed under local anaesthetic or, depending on the situation, sedation or anaesthesia. A pathologist examines the nature of inflammation and any possible tumour cells under a microscope, for example. Separate instructions are provided for care of the sampling site and monitoring while awaiting results.

A successful dietary trial requires your cat to receive only the agreed food and water. Other treats, another animal's food and occasional leftovers can make interpretation difficult. Your vet chooses a nutritionally suitable option, taking previously eaten ingredients into account. Food allergy can also develop to food a cat has eaten for a long time.

During the trial, record both foods given and changes in the skin and itching.

Improvement during a trial warrants further investigation, but the link between a suspected food and symptoms may need assessment through controlled re-exposure. This is not done by randomly switching between several foods. Your vet plans the next stage so the result can be interpreted and unnecessary dietary restrictions do not become permanent.

Watch the extent of the lip lesion, discharge, appetite and tolerance of mouth handling. Photographs can help compare the ulcer on different days, but do not replace examination if it is growing. Also tell the clinic about new skin patches, increased itching or difficulty swallowing.

If fleas are suspected, treating only one cat does not always resolve the household problem. Flea life stages can be present in carpets and soft furnishings, so the environment and other animals are included in the plan. Use only products suitable for cats: a flea product intended for dogs can be dangerous to a cat. Your vet can help choose compatible flea control for the household's animals.