Eosinophilic Granuloma Complex in Cats
- Family & Friends Vet
- Jul 31, 2018
- 3 min read
Updated: Aug 27, 2018

From the second I saw her, Opal stole my heart with her sweet little kitty face. She was the runt of the litter and the black sheep as well. All of her siblings were either white, orange or black, but Opal had a coat unlike all the rest; smoky-grey with bits of orange and black speckled across her fur. Even her eyes were a deep earthy green that mesmerized me when I looked into them. Opal was smaller than the rest of the litter and she seemed to be a bit more shy than the other kitties too. I felt a strong paternal instinct to protect her and make sure she grew up to be as strong and healthy as possible.
Months after I adopted her, it became apparent that Opal had special care requirements. Not only was she terrified of anything she’d never seen before, but her mouth was frequently red and swollen and looked painful. I immediately assumed she simply was having allergic reactions to the food I was giving her, so, I got her an allergy test, which came back negative. Regardless, I tried food after food to try and see if that would help. Eventually, I found a food that seemed to work for her as well as my other cat. After a few successful months on one food, the mouth irritation came back!
Finally, I stumbled across information about EGC or Eosinophilic Granuloma Complex; a broad term that encompasses three types of skin lesions in cats. I knew EGC was the diagnosis that had been eluding me for months.
Eosinophils are a kind of white blood cell which responds against parasites and allergens. EGC causes the immune system to have a hyperactive response to what the body perceives as an attack. The eosinophils release inflammatory chemicals to the supposed affected site in excess, resulting in lesions or granulomas usually on the mouth. Originally called “rodent ulcers,” EGC was thought to have been caused by rodent bites.

EGC can manifest in three different ways: eosinophilic plaque lesions (red, often ulcerated lesions usually located on a cat’s belly or thighs), eosinophilic granulomas (swollen, red, or round masses on the back of the thighs, but mostly on the tongue and roof of the mouth), and eosinophilic ulcers (indented lesions, often ulcerated, usually on the roof of the mouth). Opal frequently had ulcerated lesions all around her mouth and they would flare up randomly with no apparent cause. After a biopsy of her inflamed tissue, it was confirmed, and with a simple injection of a corticosteroid, Opal’s inflammation immediately went down. Although it was comforting to know that it wasn’t something more serious, it definitely worried me, especially after I discovered that some cats with EGC were becoming less and less responsive to steroidal treatment.
EGC can be diagnosed fairly simply, but what’s more important is finding the underlying cause of the EGC. So, I knew to find the allergen responsible for this hyperactive immune response would allow me to keep opal from having eruptions. Unfortunately, this is easier said than done. It seemed to be completely random; sometimes she could go months on the same food without an eruption, other times her mouth would flare up for a month at a time. There has been some research that EGC can be a genetic disposition, which holds true for Opal because one of her litter-mates had the same condition. I decided to simply take all possible measures to prevent more flare-ups. I switched all of Opal’s food bowls to glass (as opposed to steel, rubber or plastic), I made sure her toys were of a safe material as well, and I kept her to short, supervised outside play. I also discovered “Crave,” a relatively inexpensive food available at King Soopers. And Voila! Opal was having fewer flare-ups than ever, and when she did, they were much milder than before.
It is possible that you might never discover the underlying cause of your cat’s EGC, but there are always preventative measures that can be taken to minimize the effects of this condition. Fleas and ticks can be a common cause of a flare-up. Minimize your cat’s exposure to commonly known allergens. Ensure your cat’s food and litter is safe and natural, with minimal ingredients. Also get your kitty vaccinated! A cat with FIV or FeLV is much more likely to have flare-ups. EGC is going to be different in each affected kitty and it’s important to know what your cat’s personal care requirements are.
Does your cat have EGC? Let us know if you have any experience with this disorder!
Resources:
https://www2.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/eosinophilic-granuloma-complex
https://www.2ndchance.info/egc-Tilley2011.pdf
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