Skin Disease (Dermatophilosis) in Cats


PetMD Editorial

Updated Aug. 24, 2022

Dermatophilosis in Cats

Dermatophilosis is a skin disease most prevalent in warm, wet, or humid climates. This condition is rare in cats, but when it does occur, the chances of contraction are higher in cats with wet skin, or that have skin that is compromised from parasitic bites, such as from fleas or ticks, or other types of wounds. As noted, wet skin, and wet scabs, are more prone to infection, since moisture encourages the germination of zoospores and the spread of hyphae, a fungal cell, throughout the body. Humidity plays a part in increased infection rates by creating an environment for parasitic insects to breed, which in turn leave the host's (in this case, your cat's) skin open to infection.


Symptoms and Types

If you see pus filled bumps, abscesses, or crusted scabs, either in the mouth or under the skin, and there is no apparent cause for them, it might be a case of dermatophilosis. This is especially so if your cat has been in an environment with cattle, sheep or horses (or has been around people or animals that have been in such an environment). If you suspect this is the condition, and the bumps resemble those described above, you should consult your veterinarian for advice on treatment.


These bacteria are easy to recognize on sight because of their described “railroad track” appearance (also described as paint brush lines).Your veterinarian will take samples of the pus and crusted skin to analyze them for dermatophilosis bacteria. If there is pus under the crusts, it will also be examined. Once tests determine that the dermatophilosis bacteria are present, treatment will be prescribed.

Be sure to tell your veterinarian if your cat has been near farm animals or has been in an environment where there are farm animals. This information will help in determining whether the infection is dermatophilosis. A biopsy of the ulcers, and samples of the pus, will be taken from draining ulcers, if they are present.

Once tests determine that the dermatophilosis bacteria are present, treatment will be prescribed. If dermatophilosis is ruled out, further tests will be ordered to determine exactly what is causing this skin disorder.



Antibacterial shampoo will be used to cleanse the skin and hair, followed by the gentle removal of infected flesh or abscesses. One or two baths will usually be enough to begin resolving the condition. Consult your veterinarian as to which shampoo you should use.

Following the cleaning, your veterinarian may also prescribe antibiotics to be taken for 10 to 20 days, especially if the infection has become severe. The antibiotic most commonly used is penicillin, however, the following are also used, depending on the circumstance: tetracycline, doxycycline, minocycline, ampicillin, and amoxicillin.

Your veterinarian will want to see your cat again after two to three weeks, to be certain that the condition has been resolved. If the results are negative, another seven days of therapy may be prescribed.



It is possible, though unlikely, that humans can become infected after having contact with an infected cat. If any of the members of your household have compromised immune systems, it is advised that your cat be kept isolated from such persons until the condition has cleared.

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