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Localized demodicosis in cats due to inhalant glucocorticoids | VETgirl Veterinary CE Podcasts

In today’s VETgirl podcast, we review potential side effects of chronic inhalant glucocorticoids in cats.

Work in an all feline practice? Maybe you treat a lot of cats with asthma? As a criticalist, I love using inhaled drug therapy for the treatment of asthma… however, there are some potential pros and cons of using them. For example, if the lung disease is severe, IMO, patients need a course of systemic drugs first – especially when radiographic evidence is significant. (How many times do you hear criticalists saying to use systemic steroids, right? Here’s one of them!).

That said, I also love the use of inhaled drugs (such as albuterol or fluticasone) for cats with asthma, as they are great for rescue therapy. One side effect I never thought about however? Topical reactions secondary to chronic inhaled glucocorticoids! aerokat

In this VETgirl podcast, we focus on the dermatological complications from chronic inhaled glucocorticoid therapy when treating feline asthma. Dr. Bizikova out of NC State published a paper called Localized demodicosis due to Demodex cati on the muzzle of two cats treated with inhalant glucocorticoids in the journal Veterinary Dermatology in 2014 discussing a case series of two cats that ended up developing demodex secondary to chronic inhaled steroid therapy!

First, a review of Demodex in cats:

  • Demodex cati is a follicular mite in cats that is a common cause of demodicosis in cats.
  • Demodicosis can be associated with many different systemic diseases that suppress the immune system, such as steroids, cyclosporine, etc.

Well, fluticasone is a commonly used inhaled glucocorticoid used in the long term management of asthma in cats. It is administered with the aid of an inhaler mask. (These Aerokat or Aerodawg inhaler masks are made by Trudell Medical out of Canada – VETgirl loves these products and is a firm believe that every clinic should have one for the emergency management of the dyspnea cat, but that’s a whole nother podcast!).

So, in this study, Dr. Bizikova reported how demodicosis can be as a possible side effect of long term use of inhaled glucocorticoids in cats – with lesions restricted to the face! (Remember that an important infectious disease differential to have on your rule out list that could cause similar clinical lesions is dermatophytosis)

So, what can we take away from this VETgirl podcast?

  • Topical glucocorticoids can lead to local immunosuppression of the skin, allowing for infection with Demodex cati.
  • Demodex cati mites can be found with trichograms, in addition to deep skin scrapings. These mites live in the hair follicles. Plucking the hairs and placing them on a slide with mineral oil and examining under a microscope at 4X or 10X can be diagnostic. This is extremely helpful when affected skin is in an area that is difficult to perform a deep skin scraping (like around the face or the feet).
  • Remember that demodicosis can be pruritic. Demodex cati is thought to be a non-pruritic cause of alopecia in cats. However, this mite can cause pruritus as demonstrated in one of the cases reported in this article.
  • Remember: Demodicosis is a differential for hair loss, thin hair, scaling, and excoriations in a cat that is receiving inhaled glucocorticoids. You can easily diagnose it with a skin scraping or trichogram, which is an important part of the dermatological minimum database for any pruritic or non-pruritic cat.

If you do have a cat that is being treated for asthma with these inhaler masks, make sure to let the pet owners know to watch for skin lesions in the area where the mask covers the face. Again, this is super rare, but something that we should be cognizant of!

References:
Bizikova P. Localized demodicosis due to Demodex cati on the muzzle of two cats treated with inhalant glucocorticoids. Vet Derm 2014;25:222-225.

http://www.capcvet.org/capc-recommendations/demodex-mange-mite

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