An ulcer on a cat’s upper lip or an angry-looking patch of skin can be unsettling. One possible explanation is feline eosinophilic granuloma complex (EGC), a group of inflammatory skin patterns rather than a single contagious infection. These lesions often relate to allergies, but they must be examined because other diseases can look similar.
What does EGC look like?
The classic patterns include ulcers on the lip, raised and often itchy plaques on the belly or thighs, and firm pinkish or yellowish nodules or streaks on the skin. The appearance differs between cats. Some lesions are not obviously painful, while others are intensely itchy or become secondarily infected.
What triggers the lesions?
Flea-bite hypersensitivity is an important potential trigger. Environmental or food allergy, other inflammatory processes and individual susceptibility may also play roles. Sometimes the cause remains uncertain after evaluation. Seeing a lesion does not prove a specific food allergy or justify switching among random foods and supplements.
How the veterinarian evaluates it
The vet will examine the lesion, assess flea prevention and skin history, and consider skin cytology, additional testing or a biopsy if the diagnosis is unclear. An elimination diet may be suggested when food allergy is suspected, but it requires a structured trial rather than simple ingredient avoidance.
What treatment can involve
The plan may include consistent veterinarian-approved flea control, addressing infections when present, and managing inflammation or allergies. Prescription anti-inflammatory or immune-modifying drugs require individual assessment and monitoring. Never use a leftover steroid or human skin cream on a cat without professional guidance.
Practical tips for owners
- Photograph lesions over time in consistent lighting.
- Record itchiness, grooming changes and appetite.
- Follow flea-control instructions for every applicable pet in the household.
- Prevent licking or scratching when advised by the veterinarian.
- Return if a lesion grows, bleeds, changes appearance or fails to improve.
When to seek care faster
A cat who cannot eat because of mouth pain, develops rapid swelling, is markedly ill, or has a spreading wound needs prompt veterinary assessment. For related feeding concerns, see foods cats should avoid.
Reference: Merck Veterinary Manual, Eosinophilic Granuloma Complex in Cats. General educational information.
This article is for general education and is not a substitute for care from your own veterinarian. Learn about The Pet Vet and our editorial policy.