Ask the Vet: More on Pet Allergies

by Mark Nunez, DVM

Daniel Y. Go via Flickr.com

Dear Dr. Mark,

I've read that long-term use of prednisone can cause Addison's disease, Cushing's disease, and a dependence on the drug to the point where his body will not be able to produce its own corticosteroids. Is this true? Should the veterinarian be prescribing something other than Prednisone for long-term treatment of an allergy? Is there something I can be doing to help control the allergies at home? Sorry for the long questions. Thank you!

Cynthia D.

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Dear Cynthia:

Prednisone is the best medication for controlling the symptoms of allergies, no doubt about it.  However, it has a lot of side effects, especially with long-term use.  The list of side effects includes:  increased thirst, increased urine production, increased appetite, thinning of the skin and coat, dull/dry coat, weight gain, water retention, panting, vomiting, diarrhea, elevated liver enzymes, pancreatitis, iatrogenic Cushing's disease, GI ulceration, lipidemias, activation or worsening of diabetes, muscle wasting, increased susceptibility to infections and behavior changes (depression, lethargy, aggression).  Pred does not cause Addison's disease.  Cats tend to tolerate it better than dogs and side effects are rarely seen in cats.

This said, I would not, and do not, hesitate to use prednisone in my patients that need it.  There is no medication out there that works better to relieve the symptoms of a moderate to severe allergy flare up.  In some cases, it is the ONLY thing that helps.  I use pred without hesitation, but my goal is to minimize its use.  The best way to accomplish this is with allergy shots (immunotherapy, IT).  I recommend that all of my patients get allergy tested (if I suspect environmental allergies to pollen, dust, etc...) and start IT.

Nothing will cure allergies; there are only different ways of managing the symptoms.  IT is the only form of treatment that addresses the underlying cause, which is an over active immune system.  Other options only treat the symptoms.  Atopica (cyclosporin) is another long term treatment option that can take the place of pred, however, it is not without it's own set of side effects which includes: vomiting, diarrhea, anorexia, gingival hyperplasia, increased susceptibility to infections, and neoplasia (cancer) when used in combination with other immunosupressive drugs (pred).

Both pred and Atopica (the two should not be used together) also have MANY drug interactions and can be contraindicated if your dog is on certain heart medications, insulin, anti seizures medications (specifically phenobarbital), cyclophosphamide, erythromycin, mitotane, live-attenuated virus vaccines, non-steroidal anti-inflammatories (Rimadyl, Deramaxx, Metacam), antifungal medications, and synthetic estrogens.

Other medical options for controlling the symptoms of allergies include Benadryl, Claritin, Zyrtec, and Hydroxyzine.   These are all antihistamines and tend to only work on mild cases and at high doses.  There are a number of shampoos and leave on conditioners that have cortisone in them.  The most common one I use is Epi-Soothe.  This can be a good option, but is labor intensive.  Omega-3 fatty acids (fish oil), specifically Welactin, can also help and I recommend this specific brand for all allergy patients.  The brand is important because nutraceuticals are not FDA regulated and vary significantly in their bioavailability and action.

Thank you for your question and I hope I’ve helped you get a better understanding of how to treat allergies. Part I of this question was answered earlier and is linked below for reference.

Dr. Mark

courtesy M.N.

Dr. Nunez is a practicing veterinarian while also assisting patients through The Balanced Canine blog and his own online veterinary pharmacy. Have a question for Dr. Mark? Send it to AllThingsDogBlog@gmail.com. You can also follow Mark on Twitter.

Want to read more from Dr. Mark? Try these, or visit his archives: 

Dogs and Allergies (Part I of this same reader's question) Dogs Who Eat Bugs Diabetes and Allergies Combined
Dr. Mark's advice does not replace an actual examination with a veterinary professional.