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Case Study: Eosinophilic ulcer (rodent ulcer) in a cat

Case Study: Eosinophilic ulcer (rodent ulcer) in a cat

by Jennifer Jellison, DVM


Angie, a 4-year-old Persian cat, presented for a second opinion related to a lesion on her upper lip. She was not eating well and had previously been treated with steroids for her lip condition. The client reported she improved for a week or so after the steroid injection. She was an indoor cat. She was current on her vaccinations as well as deworming and FeLV/FIV (negative). She had been losing weight for about two months. The client reported today that she had begun to vomit her hard food almost immediately after eating.


Angie was bright and alert on presentation. She was very thin, weighing 4.2 pounds. Her hydration appeared normal. She had mild dental tartar. Her upper lip was grossly eroded to the point it had begun to expose her nasal cartilage. The erosion was covered in a yellow exudate. Her entire coat had broken hairs and areas of thinning. She had live fleas visible and substantial flea dirt present. Her skin did not appear inflamed or irritated other than the broken hairs which resembled chronic grooming. All other physical exam parameters were normal.

Differential diagnoses includes Flea allergy dermatitis; fungal dermatitis; eosinophilic ulcer; food allergy; skin pyoderma.

Diagnostic tests

FeLV/FIV (neg)
Internal organ function (all values wnl)
CBC (all values wnl)
Skin scrape (neg for mites)
Skin impression (neg)
Fungal culture (neg)

Discussion points to consider

  1. What supportive measures should be implemented immediately in this case?
  2. Is there any significance to the breed of cat involved in this study?
  3. Rodent ulcers have historically been treated with steroids. Are there any possible reasons the treatment has not been effective, i.e., prednisone from previous veterinarians?
  4. What parameters would you use to determine if this case should be treated or if the cat should be humanely euthanized?
  5. What is a likely cause of the vomiting episodes?


Initially, treatment while waiting for pending blood results involved preparation of an Hill's A/D gruel presented to the cat. The cat ate ravenously but due to the absence of an upper lip, had to eat by sucking in the food. When presented with hard cat food, which the client had used, the cat ravenously used its tongue to throw the food into the back of its mouth. Within 10 minutes, the cat vomited the hard food. It could eat the gruel successfully without any vomiting. Most likely the lack of proper mastication and eating the hard food whole was a cause of the vomiting.

After skin work-up and blood results were determined, the cat was treated with oral Capstar followed by Feline Advantage 24 hours later. Her home was also treated for fleas by a professional company. She was given 20 mg of Depo-Medrol IM, 400 mg of ampicillin SC. She was released on oral clavamox liquid, 80 mg bid. Based on the condition of her mouth, oral medication with pills or tablets was difficult and extremely uncomfortable for the cat.

The cat returned for a recheck one week later. She had gained 3/4 lb. and her coat was improving. No fleas were seen. She was eating the A/D gruel well. At this point she was released with instructions to continue the antibiotics.

She returned two weeks later for a recheck. Her lip was improving and the exudate had resolved with granulation tissue beginning to fill in the area. The scarring, however, led us to believe she may permanently have some prehensile challenges due to the severe nature of her original erosion. The client was educated on the allergic nature of some rodent ulcers and followed through with the recommendation for hypoallergenic diet control. Recommendations were given for Royal Canin feline duck formula. The cat readily adapted to the canned formula and was weaned off of the A/D.

At six month follow-up, the cat had gained a total of 3 pounds. Her hair coat had regrown completely and her lip, although scarred, had regenerated fairly well.


Indolent ulcers occur on the upper lip of cats at almost any age. Routinely, steroids have been used as the first treatment choice1. There has been evidence that some cats have a genetic predisposition to these ulcers when exposed to specific trigger antigens, particularly fleas2. In this case, the initial steroid treatment may have failed because the underlying flea infestation was not addressed. Atopy can also be a trigger in these cases. For this case, food allergy could not be ruled out as an additional allergen, so once the cat could eat well she was transitioned to a hypoallergenic diet. The recommendation was for lifelong flea control and diet control to help reduce the recurrence of the lesion.


  1. Nelson RW, Couto GC. Small Animal Internal Medicine. 2003; 407.
  2. August J. Consultations in Feline Internal Medicine. 2006; 242.