Eosinophilic Granuloma Complex in Cats: Symptoms, Causes, and Treatment

Approaches to ease allergy-driven lesions and keep your feline friend comfortable.

By Srija Burman

Created on Sep 2, 2025

Approaches to ease allergy-driven lesions and keep your feline friend comfortable.

Eosinophilic Granuloma Complex in Cats

Eosinophilic granuloma complex (EGC) is a group of chronic skin and oral diseases seen in cats. It is characterized by the presence of inflammatory lesions, which are most often the result of an underlying hypersensitivity or allergic response. The condition may be triggered by fleas, food components, environmental substances, or other unknown factors. This article explores the types, causes, diagnosis, treatment, and prognosis of EGC, equipping cat owners and veterinary professionals to better understand andmanage this common feline dermatological condition.

What is Eosinophilic Granuloma Complex?

EGC is not a single disease, but a collection of related disorders marked by the infiltration of eosinophilsâa type of white blood cellâinto the skin and sometimes the mouth. This response forms unique lesions, with three primary patterns:

Eosinophilic granuloma
Eosinophilic plaque
Indolent ulcer (sometimes called rodent ulcer)

These lesions can appear separately or together, and may vary widely in presentation and severity from cat to cat.

Types and Clinical Presentation of EGC

Type	Location	Appearance	Symptoms
Eosinophilic Granuloma	Rear legs, mouth, lips, body	Raised, firm, linear, yellowish-pink lesions; may range from bumps to large ulcers	May be itchy, secondary infection if scratched, swelling in lip or palate
Eosinophilic Plaque	Abdomen, thighs	Red, moist, raised, “angry” looking hives or plaques	Very itchy, cat often licks or scratches
Indolent Ulcer	Upper lip, oral cavity	Shallow, well-demarcated ulcer or sore, may be chronic	May not be painful, slow to heal, swelling of lip

Some cats may only show one type of lesion, while others may exhibit two or more simultaneously. Lesions frequently recur, can range from minor cosmetic issues to severe ulcers, andâif unaddressedâmay result in secondary bacterial infection due to constant scratching or licking.

Causes and Risk Factors

The exact cause of EGC is poorly understood, but an allergic reaction is considered the most likely trigger. Common factors include:

Flea allergy: The most frequent trigger; a single bite can provoke a dramatic reaction in sensitive cats.
Food allergy: Some cats react to certain proteins or additives in their diet.
Environmental allergens: Pollen, dust, mold, or other atmospheric substances.
Insect bites: Mosquitoes and other biting insects.
Medications: Occasionally, cats on certain drugs (antibiotics, cardiac meds) develop lesions.

In some cases, no direct cause is identified, and the condition is assumed to be idiopathic (of unknown origin).

Diagnosis

Diagnosing EGC typically involves:

Clinical examination: Visual inspection of lesions and review of symptoms.
Skin cytology: Microscopic analysis to identify eosinophils.
Biopsy: Tissue samples taken for histopathological confirmation.
Laboratory testing: Blood work in select cases to rule out other diseases, assess allergy markers.
Elimination diets: If food allergy suspected, cats are switched to hypoallergenic foods to monitor lesion resolution.
Parasite screening: Flea comb test and possible ectoparasite treatments to rule out flea-driven hypersensitivity.

Additional testing, such as *in vitro* or *in vivo* (skin prick or blood tests) allergy testing, may be recommended if initial management is ineffective and environmental allergies are suspected.

Clinical Course

The progression and severity of EGC can vary largely between individuals. Some lesions may:

Resolve spontaneously without intervention, especially if small and not bothersome to the cat.
Persist or worsen, particularly if the underlying cause is not removed.
Lead to significant discomfort, secondary infection, or even disfigurement if severe ulceration develops.

Early and effective intervention is essential to prevent complications and chronicity.

Treatment Options

Treatment focuses on both symptomatic relief and identification/removal of the underlying cause when possible. Strategies include:

Allergen avoidance
- Flea control: Rigorous flea prevention is essential for all cats with EGC, regardless of confirmed flea allergy.
- Diet trials: Hypoallergenic diets can identify or rule out food triggers; strict adherence required for effective testing.
Medical management
- Glucocorticoids (steroids): Oral tablets, long-lasting injections, or topical sprays reduce inflammation and prompt resolution of lesions. Duration varies, often requiring several weeks or long-term intermittent therapy. Steroids are generally well tolerated in cats but can cause side effects with prolonged use, such as weight gain.
- Immunosuppressants: Drugs such as cyclosporine and chlorambucil help control severe or refractory cases and may minimize steroid use.
- Antihistamines: Occasionally used, especially with prominent itching.
- Antibiotics: If secondary bacterial infection is present, topical or oral antibiotics may be prescribed.
- Topical therapies: Hydrocortisone aceponate spray, tacrolimus ointment, laser surgery, or specialized wound healing ointments may be considered for local treatments, especially for ulcers or stubborn plaques.

Not all treatments are suitable for every cat; individual plans are devised by veterinarians based on clinical signs, response to initial therapy, and concurrent health problems.

Long-term Management and Prognosis

EGC tends to recur, often requiring lifelong intermittent therapy and meticulous attention to underlying triggers:

Prognosis: Most cases respond well to medical management, but continued recurrence means many cats need periodic or chronic treatment.
Lifestyle modifications: Strict flea prevention, dietary adjustments, and environmental allergen reduction can improve lesion control.
Referral: Severely affected cats may benefit from consultation with a board-certified veterinary dermatologist.

Side effects of long-term steroid use are less significant in cats but should be monitored, especially if extended durations or high doses are required. Regular updates with the veterinarian ensure ongoing best care and prevent complications.

Prevention Strategies

Year-round flea control: Essential even in indoor-only cats; effective products include spot-on treatments and environmental management.
Dietary evaluation: Use limited ingredient or hydrolyzed hypoallergenic diets if food allergy suspected; avoid sudden change to new diets without veterinary advice.
Environmental allergen minimization: Regular cleaning, air filtration, and avoiding exposure to known triggers can help.
Prompt medical attention: Early assessment and therapy can prevent severe lesions and secondary complications.

Prevention is often challenging due to the multifactorial causes of EGC, but managing known allergens and maintaining regular veterinary care are the best defenses.

Living With a Cat Diagnosed with EGC

Many cats with EGC live full and happy lives when managed appropriately:

Maintain recommended flea control year-round.
Feed prescribed hypoallergenic diets strictly, avoiding table scraps or treats unless approved by your veterinarian.
Monitor for new or recurring lesions and seek veterinary advice promptly.
Attend regular veterinary follow-ups for long-term management, medication adjustment, and monitoring for side effects.

Owners should be vigilant for secondary infections, excessive scratching, or dramatic changes in lesion appearance, which may require urgent intervention.

Frequently Asked Questions (FAQs)

Q: Can EGC be cured?

A: While EGC can seldom be ‘cured,’ it can be managed effectively in most cats through allergy control, medication, and ongoing veterinary care. Lifelong intermittent therapy may be needed, given frequent recurrences.

Q: What do EGC lesions look like?

A: Lesions may include raised bumps, ulcers, plaques, or erosions. They often appear anywhere on the body but are most common on the rear legs, lips, and abdomen.

Q: Is EGC contagious to other cats or humans?

A: No. EGC is an allergic and inflammatory condition, not infectious or contagious.

Q: Will my cat need steroids forever?

A: Not all cats require continuous steroids. Long-term intermittent use is common, but some cases may be controlled with allergen avoidance and other therapies. Your veterinarian will tailor treatment to minimize side effects and optimize comfort.

Q: What are the risks of untreated EGC?

A: Untreated lesions can become chronically infected, ulcerated, and may cause widespread discomfort or even disfigurement. Early intervention is critical for maintaining quality of life.

Q: Can I prevent EGC in my cat?

A: While not all cases are preventable, controlling fleas, feeding an appropriate diet, and minimizing exposure to environmental irritants reduce risk. Timely veterinary care is essential for diagnosis and management.

Key Points and Owner Checklist

EGC is a group of allergic/inflammatory skin disorders in cats, frequently recurring and often linked to flea, food, or environmental allergens.
Three main lesion types: eosinophilic granuloma, eosinophilic plaque, and indolent ulcer.
Diagnosis includes visual exam, skin cytology, biopsy, and allergy exclusion through diet and parasite control.
Treatment focuses on allergen avoidance and symptomatic relief; most cases managed with steroids and/or immunosuppressants.
Lifelong management is often required; prognosis is good with appropriate therapy.
Prevention relies on flea control, dietary evaluation, and rapid intervention.

Additional Resources

Talk to your veterinarian if you suspect your cat has skin lesions or persistent itching.
Seek guidance from a veterinary dermatologist for complex or refractory EGC cases.
Consult reputable veterinary sources for updates on feline allergies and dermatology.

References

Author

Srija Burman

Srija holds an MA in English Literature from the University of Calcutta and a PG diploma in Editing and Publishing from Jadavpur University. Her interest in writing and editing ranges across niches, including academics, sports, and human psychology.

Read full bio of Srija Burman