Eosinophilic Granuloma Complex in Cats


Overview of Feline Eosinophilic Granuloma Complex 

The term eosinophilic granuloma complex (EGC) refers to a group of skin lesions that represent an allergic reaction in the cat’s skin. These occur in three forms, and your cat may have any or all of them. These forms include:

  • Eosinophilic granulomas. These nodules are raised, yellow or pink in color, and usually are not itchy. They occur on the back of the rear legs, in and around the mouth and on the face and are most common in adolescent kittens.
  • Eosinophilic plaque. These patches look like a raised, round red lesions that may be ulcerated. They are usually itchy and are most commonly found on the belly, inner thigh or throat.
  • Indolent ulcer. Erosions on the margin of the upper lip and sometimes on the tongue are red in color and glistening in appearance. They may be painful and may affect the cat’s willingness to eat.

    On microscopic examination of skin biopsy specimens, all of these forms of the disease are characterized by accumulation of large numbers of eosinophils, a type of white blood cell found in allergic and parasitic inflammatory disorders.

    A common cause is thought to be flea allergy, but atopy, a form of allergy triggered by inhaled environmental allergens such as pollens and dust, and food allergies also can cause EGC lesions in cats. An allergic response to mosquitoes is also suspected.

    Female cats may be more likely to be affected than male cats, but only rarely is it found in dogs, such as Siberian huskies.

    Diagnosis of Eosinophilic Granuloma Complex in Cats

    Diagnostic tests may be needed to diagnose eosinophilic granuloma complex and assess the extent of the disorder and its effects on the cat. Often, a presumptive diagnosis is made based on the clinical appearance of the lesions and their response to treatment. Tests may include:

  • A complete medical history and physical examination. Physical examination is very important because of the distinctive clinical appearance of the lesions.
  • A complete blood count (CBC or hemogram) to evaluate for anemia, infection, inflammation and circulating eosinophils
  • Skin biopsy to rule out other causes of lesions with a similar appearance – most notably skin cancers such as squamous cell carcinoma or cutaneous lymphosarcoma. The results of the skin biopsy will confirm the diagnosis of eosinophilic granuloma complex.
  • Treatment of Eosinophilic Granuloma Complex in Cats

    Treatment for eosinophilic granuloma complex may include one or more of the following:

  • Corticosteroids. Cortisone-like drugs are used most commonly to treat cats with suspected eosinophilic granuloma complex. Unlike other feline skin reactions such as miliary dermatitis, the lesions of eosinophilic granuloma complex rarely respond to removal of the allergen alone. The anti-inflammatory effects of corticosteroid drugs such as prednisone and methylprednisolone acetate are usually needed.
  • Flea control, elimination diets to identify food allergens, and treatment for inhaled allergens (those that cause atopy) may help prevent recurrence.
  • Home Care and Prevention

    At home, administer as directed all medications prescribed by your veterinarian, and contact your veterinarian if you are having difficulty medicating your pet or if the condition has worsened.

    Follow-up appointments are very important because the lesions of eosinophilic granuloma complex often require more than one treatment for complete success.

    Preventative measures include flea control, elimination diets to identify food allergens and treatment for inhaled allergens.

    In-depth Information on Eosinophilic Granuloma Complex in Cats

    Eosinophilic granuloma complex refers to a characteristic allergic skin reaction in cats. Flea allergy is thought to be the most common cause of this type of allergic skin reaction. Allergic reactions to food components, which are allergens that are inhaled into the respiratory system (atopy), and allergic reactions to other insects such as mosquitoes also can result in eosinophilic skin lesions. In unusual cases, an allergic cause cannot be found and a hereditary disorder is suspected.

    Eosinophilic plaques usually are found on the abdomen or the inner thighs. They are raised, red lesions that may be glistening in appearance or oozing serum. Eosinophilic plaque lesions are extremely itchy (pruritic) and often are surrounded by broken hairs from constant licking of the area by the cat with its barbed tongue. Other skin diseases that can produce similar lesions include bacterial or fungal infections and some types of skin cancer including mast cell tumors and cutaneous forms of lymphosarcoma.

    Eosinophilic granulomas often are found on the backs of the legs, on the roof of the mouth or on the tongue, and on the lower lip causing the cat to have a pouting expression. Lesions on the back of the legs usually are raised, round, and pink or yellow in color. More than one lesion may be present and they tend to occur in a linear distribution along the leg. As with eosinophilic plaques, bacterial and fungal infections and certain types of skin cancer such as mast cell tumor and cutaneous lymphosarcoma can have a similar appearance.

    Indolent ulcers, also called rodent ulcers almost always are found on the upper lip and usually are confined to one side. Occasionally, they may be found on both sides of the lip or inside of the mouth. The lesions most often are raised and ulcerated, causing a dramatic change in the appearance of the lip. Indolent ulcers may represent a precancerous lesion and, if untreated, eventually may develop into a malignant skin tumor called squamous cell carcinoma. Once again, bacterial and fungal infections and skin tumors (including mast cell tumor, cutaneous lymphosarcoma and squamous cell carcinoma) are diseases that may result in a similar appearance.

    In some cats, more than one type of eosinophilic skin disease can occur simultaneously.


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