Crusts and pustules on a pet’s skin are sometimes caused by the pet’s own immune system. Pemphigus foliaceus is an autoimmune skin disease, and among the autoimmune skin diseases it is the one dogs and cats get most often. Akitas and Chow Chows may be more prone to it. [1]
This guide explains what happens in the skin, what it looks like, how vets confirm it, and what long-term treatment involves.
What happens in the skin
Skin cells (keratinocytes) are held to one another by tiny attachment points called desmosomes. In pemphigus, the immune system makes antibodies against parts of these attachments. That sets off a chain of events that breaks the links, so the skin cells come loose, round up and float free. [2]
Because this happens in the very top layers of the skin in pemphigus foliaceus, the pustules that form are fragile. They burst quickly and are replaced by yellowish to light brown crusts, which is why owners usually see crusts rather than pustules. [1]
A similar reaction has occasionally been linked to certain medicines, including some antibiotics and some topical flea and tick products, so tell your vet about anything your pet has been given recently. [2]
What it looks like in dogs
A study that reviewed 91 dogs with pemphigus foliaceus recorded these signs: [3]
- Crusts (79 dogs)
- Pustules (36 dogs)
- Hair loss (33 dogs)
The trunk was the most frequent site (53 dogs), followed by the inner ear flaps (46), the face (37) and the foot pads (32). [3] Lesions often begin on the top of the muzzle, and the pads can thicken and crack. Itch and pain vary, and most dogs still feel well, although a few become dull and lose their appetite. [1]
What it looks like in cats
A review of 49 cats seen at a veterinary teaching hospital found the ear flaps, the head and face, the nose and the skin folds around the claws to be the areas most often affected. Many of the cats were itchy, and many showed signs of being unwell in general. [4] Inflamed, crusted nail folds with pus are a typical feature of the disease in cats. [1]
For other causes of crusting on and around the nose, see dry, crusty nose in dogs, which covers pemphigus alongside lupus and infections.
How vets diagnose it
Vets look at material from a fresh pustule, or from under a crust, under the microscope. Finding many loose, rounded skin cells together with white blood cells supports the diagnosis. [1] In the 91-dog study, these loose skin cells were seen in 37 of the 48 dogs whose samples were checked this way. [3]
A skin biopsy is the most important test, and the result is read together with the history and the pattern of lesions. Bacterial infection, ringworm and drug reactions can look similar, so they need to be ruled out. [1] The 48-cat study included only cats whose diagnosis was confirmed by a skin biopsy. [5]
See also pyoderma in dogs.
How it is treated
Treatment aims to calm the immune attack on the skin. Vets use steroid medicines and other immune-suppressing medicines, alone or in combination, and choose them for the individual pet. Some medicines that suit dogs are not safe for cats. [1] Any secondary skin or ear infection is treated as well. [2]
Dogs. In the 91-dog study, over half of the dogs went into remission with suitable treatment, and roughly a quarter more got much better. [3] Results differ between studies: in a separate review of 43 dogs, 60.5% of the dogs died or were put to sleep. Dogs that had more side effects from treatment lived for a shorter time, which the authors linked to owners choosing euthanasia and to illnesses caused by the steroid treatment. Dogs that were still alive after ten months of treatment tended to do well over the long term, so the authors stressed close care in the first months. [6]
Cats. In a study of 48 cats treated in general practice, 36 of the 40 cats with follow-up records (90%) went into remission, but 29 of those cats (73%) later relapsed and needed their medicines changed. [5] The authors concluded that cats very often reach remission, that relapses are frequent, and that cats should be watched closely. [5] In the 49-cat study, a single steroid medicine was enough to bring most cats into full remission, but treatment had to continue long term, and living with the disease and its care lowered quality of life for cats and owners alike. [4]
Side effects. Eight of the 48 cats had serious side effects from treatment, and the authors recommended regular rechecks so that doses can be adjusted as the disease changes. [5]
Living with pemphigus foliaceus
- Expect regular rechecks, especially in the first months. [5][6]
- Expect long-term treatment in many pets. [4]
- Relapses can happen, so tell your vet if new crusts or pustules appear. [5]
When to see your vet
Book a visit if your pet has:
- Pustules or crusts on the face, ears, nose or foot pads
- Crusting around the claws (in cats)
- Crusty skin along with lethargy, poor appetite or fever
- Crusts that do not clear with treatment for infection
FAQ
Can it be cured?
Many pets go into remission with treatment, but long-term treatment and relapses are common, particularly in cats. [3][4][5]
Is it common?
Autoimmune skin disease is not something most pets get, but pemphigus foliaceus is the most common of these diseases in dogs and cats. [1]
The bottom line
Pemphigus foliaceus is an autoimmune disease in which the immune system attacks the attachments that hold skin cells together, causing fragile pustules and crusts, often on the face, ears and feet, and around the claws in cats. Vets confirm it with tests on the lesions and a biopsy, and most pets respond to immune-suppressing treatment, though many need long-term care and close monitoring.
This article is for general information and is not a substitute for veterinary advice. If your pet has crusts or pustules on the skin, please see your veterinarian.
Sources
- Torres SMF. 2.3 Pemphigus Foliaceus. Small and Large Animal Dermatology Handbook, Vol. 2. University of Minnesota, 2025. CC BY 4.0. https://open.lib.umn.edu/animaldermatology2/chapter/pemphigus-folicaceus/
- Torres SMF. 2.2 Pemphigus: General Considerations. Small and Large Animal Dermatology Handbook, Vol. 2. University of Minnesota, 2025. CC BY 4.0. https://open.lib.umn.edu/animaldermatology2/chapter/pemphigus-dogs-and-cats/
- Mueller RS, Krebs I, Power HT, Fieseler KV. Pemphigus foliaceus in 91 dogs. J Am Anim Hosp Assoc. 2006;42(3):189-196. PMID 16611930. https://pubmed.ncbi.nlm.nih.gov/16611930/
- Jordan TJM, Affolter VK, Outerbridge CA, Goodale EC, White SD. Clinicopathological findings and clinical outcomes in 49 cases of feline pemphigus foliaceus examined in Northern California, USA (1987-2017). Vet Dermatol. 2019;30(3):209-e65. PMID 30779233. https://pubmed.ncbi.nlm.nih.gov/30779233/
- Coyner K, Tater K, Rishniw M. Feline pemphigus foliaceus in non-specialist veterinary practice: a retrospective analysis. J Small Anim Pract. 2018;59(9):553-559. PMID 29961990. https://pubmed.ncbi.nlm.nih.gov/29961990/
- Gomez SM, Morris DO, Rosenbaum MR, Goldschmidt MH. Outcome and complications associated with treatment of pemphigus foliaceus in dogs: 43 cases (1994-2000). J Am Vet Med Assoc. 2004;224(8):1312-1316. PMID 15112781. https://pubmed.ncbi.nlm.nih.gov/15112781/