Pemphigus foliaceus: an overview

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Over 30 years ago, the first case of pemphigus foliaceus (PF) was written about with numerous case reports published; however, there are fewer larger case series.¹ Although it is a rare condition, it is the most common autoimmune disease in both cats and dogs. Because it is common within the species but rare overall, it can present itself in the veterinary clinic at any time, making it important for teams to know the symptoms of the disease, how to treat it, and how to talk to clients about their pet’s diagnosis.

Veterinary dermatologist Britt Levy, VMD, DACVD, with Pet Dermatology Center in Philadelphia, Pennsylvania, gave a breakdown of this autoimmune disease, how it affects patients, and how veterinary teams can better prepare if a case of PF presents itself in their veterinary clinic to help make sure those experiencing PF are recognized and treated accordingly, during an interview with dvm360.

“Pemphigus is an autoimmune disease where, essentially, auto-antibodies are targeting the junctions between the skin cells in dogs and cats, and basically that causes a loss of adhesion between those cells, and it leads to pustules in the skin. What you see clinically is a dog or a cat that has pustules, crusts, hair loss, usually in a symmetrical pattern on the face, and often on the paws, and sometimes on the trunk as well,” explained Levy.

What is pemphigus?

PF is characterized by vesicles and bullae within the patient’s mouth and mucocutaneous junction, and commonly affects the eyelids, lips, nostril, and anus.²

“Usually the pustule, which is the primary lesion, is very transient. You might not even see that part. And they’re very fragile. What you’ll see is crust and bumps on the nose, the nasal bridge, on the ears, or on the paws,” said Levy.

“In the cats, they often get pus and crust on their nail beds. Both species can often have patchy hair loss and crust, it’s usually...the honey-colored crusting, and then in dogs, especially, they will often get secondary skin infections as a result, and they can be very itchy,” she continued.

If veterinary teams suspect their patient has PF, the team will need to take a cytology of any lesions first to check for a special cell called an acantholytic keratinocyte. If they are seen, the next step would be to biopsy of the affected skin, with a local anesthetic. Veterinary teams may also need to sedate or use general anesthesia on the patient if the affected area is the face or if the patient is anxious. Levy warned that certain forms of bacterial skin infections can mimic the symptoms of PF in dogs, so a cytology to check for infection is crucial prior to making a diagnosis of PF.

Causes and treatment

According to Levy, a lot remains unknown about PF, including what causes it. In some cases, PF can be linked to topical flea and tick medications. If this is the cause, you can see the lesions of PF on the back of the dog where the client would have administered the topical treatment. As for treatment of itself, it will always be dependent on the infected pet.

“Every dog is a little different and every case has to be looked at differently. This is a disease that is not easy to manage, especially in dogs.…I can say that unless there’s a specific contraindication to using glucocorticoids or steroids, most dogs are going to need to be suppressed initially in order to get into remission and are going to need relatively high doses of steroids in order to have remission induced.”

Levy said dogs experiencing PF can be managed and can avoid long-term steroid adverse effects when these drugs are used to get the pet into remission, but practitioners can add a steroid-sparing secondary agent such as cyclosporine. Veterinary teams should be aware that treatment-related adverse effects typically start when pets are on lower doses for weeks, not after the initial large dose. Levy said “scary” side effects can include gastrointestinal ulcers and common adverse effects can include increased thirst and urination.

In conclusion

PF is a lifelong disease and it is important that pet owners understand its seriousness to help keep their pet healthy and happy. Levy recommends taking time to sit down with them and go over a treatment plan to help them understand and feel supported as they begin to tackle the disease.

“I have an hour-long appointment to really be able to explain the disease to them and explain what is involved in the management. And I think that’s part of the reason why it’s so helpful. If they do come to a dermatologist, you need a good 30- to 40-minute [visit] to be able to truly set out what this disease is and what the trajectory is going to look like. I’m really up front with them and I’m like, ‘Listen, this is a tough disease’” Levy said.

“You have to be very honest and say, ‘It is not fatal, but it is like having diabetes, in that if you don’t take your medicine and you don’t keep going to your checkups and don’t get your blood work, you could get very sick or die,’” she concluded.

References

1. Bizikova P, Burrows A. Feline pemphigus foliaceus: original case series and a
comprehensive literature review. BMC Vet Res. 2019;15(1). doi:10.1186/s12917-018-1739-y

2. Van den Broek A. Autoimmune skin diseases in cats. In Pract. 1991;13(5):175-179. doi:10.1136/inpract.13.5.175