Common Feline Illnesses

Explore our
library of

Get the facts on more than 20 feline illnesses. Browse information, links to helpful sites and other resources now.

Disease Overview

Allergies that affect a cat's skin are grouped together under the term "allergic dermatitis." Cats can suffer allergies related to food, environment (atopy), and fleas and other parasites. Diagnosis can be difficult and is mostly a matter of ruling out certain causes. Often, there is never a confirmed diagnosis.

Possible Cause(s)

  • Fleas that cause bites on the skin
  • Food ingredients
  • Environmental allergens that the cat breathes in or absorbs through the skin, such as dust mites, pollen, fungi, yeast and molds
  • Idiopathic (no known causes)

How Diagnosed

  • History of cat’s exposure to certain causes, including type of food eaten and environment (indoor or outdoor cat)
  • History of ear infections (otitis externa)
  • Veterinary physical exam to rule out fleas, other parasites, and bacterial, fungal and yeast infections
  • Skin scrapings in areas of bumps or scales for lab analysis
  • Elimination diet to determine ingredients that might be causing a food allergy
  • Skin testing where allergens are injected into the skin to determine a hypersensitivity

Clinical Signs

  • Itchy skin (pruritus) and scratching
  • Red bumps or scaly areas
  • Red, sore, irritated skin
  • Ulcers on the upper lips
  • Darkened skin that may feel thicker than normal
  • Thinning or hair loss
  • Excessively licking the same area
  • Frequent shaking of head
  • Recurrent ear infections

Risk Factors

  • All cats of any age
  • May be a genetic susceptibility to certain allergens in some cats
  • Environment that includes fleas, dust mites, mold and fungi
  • Feeding table scraps

Treatment depending on clinical signs and lab data

  • Eradicating fleas on the cat and in the home
  • Eliminating certain food ingredients
  • Medications to treat fungal and bacterial causes
  • Medications to reduce itchiness and scratching due to atopic dermatitis (i.e., antihistamines and/or steroids)
  • Soothing, medicated shampoos, conditioners and sprays
  • Elizabethan collars to prevent scratching


  • Flea-free home and yard
  • Keeping cat indoors if outside seasonal allergens are the cause
  • Reducing levels of dust mites, mold and fungus in the home
  • Feeding only a diet that does not have identified food allergens