What makes dogs itch?

Dogs are taken to veterinarians for itching more than for any other medical problem. But what makes dogs itch?  While there are many possible causes, most dogs that are itchy suffer from one of these six conditions:

  • Flea allergy dermatitis
FAD distribution
Flea allergy dermatitis distribution
  • Atopic dermatitis
  • Food allergy dermatitis
  • Contact dermatitis
  • Sarcoptic mange
  • Demodectic mange

To take a quick look at the body locations commonly affected, the symptoms, and the types of lesions associated with each of these conditions, check out www.itchology.com. Itchology is the app for dedicated pet parents to mange their itchy dogs.

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Experience with Apoquel® (oclacitinib) for the treatment of 117 allergic dogs. Part 1: control of itch.

Jon Plant, DVM, DACVD

We started hearing about a new drug to control the itch of allergic dermatitis and canine atopic dermatitis in dogs over 1 year of age at the Vancouver World Congress of Veterinary Dermatology. The research showed some amazing findings. Like most veterinary dermatologists, I was eager to try it in my practice. I started prescribing (oclacitinib) Apoquel® for itchy dogs at SkinVet Clinic in November 2013. As of August 2014, I had treated over 100 dogs with Apoquel.

Dogs with skin allergies can have skin lesions and odor, but the thing that is most troublesome to pet parents (and the dogs!) is the itch that can make them miserable. At SkinVet Clinic, we ask pet owners to grade their dog’s itch level at each examination using a validated visual analog scale (0 – 10). While this is the best method that we have had to grade itch in practice, it gives an incomplete picture of itch severity over time. Soon, pet owners and veterinarians will be able to easily record and view a more complete itch diary using the Itchology app for iPhones (see www.itchology.com for more info and to sign up to get notified when it is released).

This graph shows the owner-reported itch level of dogs before Apoquel blogtreatment and after 1, 3 and 6 months. Both per-protocol data (dogs returned for recommended follow-up examinations at 1, 3, and 6 months) and intent-to-treat (ITT) data (previous value carried forward when dogs did not return for examinations or medication was discontinued) are shown.

  • 117 dogs started taking Apoquel at least 40 days ago (day 0 median = 6.0). Month 1 itch level scores were available for 104 of these (median = 2.5). The ITT data yielded similar results taking into account carried-forward values for the 13 dogs that did not return (median = 2.7).
  • 108 dogs started taking Apooquel at least 3 months ago (day 0 median = 6.0). Month 3 itch level scores were available for 85 of these (median = 2.0). The ITT value was slightly higher (median = 2.5).
  • 91 dogs started taking Apoquel at least 6 months ago (day 0 median of these 91 dogs = 5.7). Month 6 itch level scores were available for 59 of these (median = 2.3). The ITT value was similar (median = 2.5).
  • The percentage of dogs that achieved a level of itch considered “normal” by dog owners (0.0-1.9) was 36.8% at 1 month, 39.8% at 3 months, and 40.7% at 6 months (based on ITT values). Many others were in the “very mild” itch category.

These findings are remarkable, considering that most of the dogs began taking Apoquel during cooler, winter months and follow-up examinations more often occurred during warmer months, when many dogs with allergies would be flaring up. Further, as this was not a rigorous clinical trial, the day 0 itch level was often recorded while the dogs were still taking other medications – from prednisone to Atopica®. (These were discontinued for three days prior to the owner initiating Apoquel, in most cases.) Therefore, it is likely that the day 0 itch level reported here was slightly lower than it would have been with a medication wash-out period.

All in all, Apoquel has performed as expected in my hands. Check back to read my next post concerning Apoquel side effects. And, don’t forget to visit www.itchology.com to sign up for Itchology, a must-have app to help your vet help your itchy pet!

How itchy is your dog, really?

By Jon Plant, DVM, DACVD

Scratching, biting, chewing, rubbing, and excessive licking can all be signs of itch in dogs. A number of methods have been developed to try to quantify itching, but these are most useful in research settings.  One method is to take videos of kenneled dogs then track all itching behavior seen over a period of time.  Another idea that I have published research itchy-dogon is the use of sophisticated motion sensors attached to dogs’ collars. The most widely used method is to ask the dog’s guardian to rate the level of itch severity on a linear scale.

Why might measuring itch be important, you ask? I think of it like this: would you start a weight loss program without knowing how much you weigh? Excessive itching has a negative impact on dogs’ quality of life.  Surprisingly, most veterinary medical record standards do not require us to record itch severity. A meaningful measure of itch severity that you could share with your veterinarian would be a great step forward in helping pet owners help their itchy dogs.