by Dr. Dave Erlewein
If you’ve ever owned a dog with allergy-based itching, your veterinarian may have used one of the cortisones during treatment. Cortisone is another name for cortisol, the natural hormone produced by the body’s adrenal gland. Many synthetic forms of cortisone are available, and the group commonly referred to as steroids. With canine allergies being such a common problem, the ability to reduce or eliminate inflammation is what makes these drugs useful. However, they can have some negative effects, which is why your retriever shouldn’t be on them for too long.
But before we talk about getting your pet off of steroids, we need to first talk about and appreciate the value of these drugs. These drugs are highly effective in relieving the pain and suffering of a severely itchy pet. Licking, biting, chewing, and scratching can make your pet’s existence miserable. There is simply no drug or treatment more effective than steroids for rapid relief of inflammation and itch.
So, if steroids are so helpful, why do we want to decrease their use? Well, like all drugs that have a wide or systemic effect on the body, some of the effects are unwanted and may be damaging. Increased thirst and more frequent urination are the two side effects most often seen. Additionally, the pet’s appetite may be dramatically increased, which usually causes weight gain. These effects are dose related, that is, the higher the dose, the more pronounced the effect.
With long term use there may be kidney and/or liver damage and some pets may develop urinary tract infections, skin disorders, or diabetes. Consequently, the goal of steroid therapy is to get the itch and inflammation under control as rapidly as possible and keep both the dose and duration of steroid use to a minimum. Ideally, we limit the use of the steroids to the times when symptoms peak and employ other treatments to maintain comfort and control.
Antihistamines are the most frequently prescribed drugs to replace or reduce steroid use. Histamine, a bio-chemical produced by various cells in the body, is the primary mediator of allergy in humans but not dogs. In dogs, the skin is the target organ for allergic inflammation and itch and though histamine is involved, it is dramatically less important. Thus, antihistamines are helpful but seldom give complete control. Often, two or three antihistamines are used together to effect itch relief. As a class, antihistamines are relatively inexpensive, nearly free of side effects, and extremely safe drugs. While they may not entirely suppress itching by themselves, they can be very effective in keeping the doses of steroids to a minimum. Drowsiness is the primary side effect.
There is now adequate research to indicate that fish oils (primarily omega-3) and evening primrose oils have considerable anti-inflammatory properties and are very helpful in controlling inflammation and skin itching. This is especially true when combined with other agents. These are not the coat supplements advertised for a “healthy appearing coat” that contain higher amounts of omega-6 oils and other fatty acids. The anti-inflammatory fish oils are also helpful in decreasing joint inflammation caused by arthritis.
Cyclosporine is an immune-modulating drug originally used in organ transplants. As allergic dermatitis has some immune-mediated components, cyclosporine is often effective in controlling chronic allergies. Around 20-30 percent of dogs will experience stomach upset when starting the drug. This usually resolves by itself or with dosage manipulation. Expense is the primary objection to cyclosporine. A generic product is available.
There are literally hundreds of topical products available for the itchy pet. The colloidal oatmeal shampoos, cream rinses, and other anti-itch shampoos can be helpful in controlling itching. These products remove allergens from the coat and reduce skin inflammation. The most important (and most difficult part of using these products) is that the product must remain in contact with the skin for at least 10 minutes. Fifteen minutes is even better. Without this prolonged skin contact, these products are not very effective. Cortisone shampoos and hydrocortisone plus oatmeal shampoos used twice weekly were helpful in controlling itching and did not cause the side effects typical of steroid therapy. Colloidal oatmeal is also available as a spray and lotion for use in between baths.
Topical steroid creams, ointments, and sprays are useful in treating small lesions and provide excellent relief from the pain and irritation of inflammation. They are absorbed into the skin and can produce systemic side effects if ingested by licking or used long term or over large areas. Aloe vera gel (100 percent) can be very soothing on sores and severely inflamed areas. Pure aloe vera gel is not harmful if licked off by the pet.
The only treatment for allergy that is designed to attack the cause of the disorder is ASIT or Allergen Specific Immunotherapy. With ASIT, the pet is first tested for allergy by either skin tests or blood tests to find out what in the environment or diet (allergens) is likely causing the allergy symptoms. Then, a serum is prepared from these materials and a series of injections is given that is designed to “desensitize” the patient to these allergens. The initial injections are very weak and given two or more times weekly and as the dose is increased, the interval between injections is lengthened until the injections are only once a month. The main drawback to ASIT is expense, and that it is seldom so effective that concurrent drug use is unnecessary. Various studies have indicated that 60-70 percent of the patients experience at least a 50 percent decrease in symptoms. Most veterinary dermatologists say that it will take nearly a year of ASIT injections before benefits become obvious.
In summary, if your pet has a short seasonal allergy, use a short course of steroids to get the itch under control and maintain control with antihistamines and topical products. If your pet has a non-seasonal year round allergy, consider ASIT, antihistamines, topicals, and cyclosporine. If expense a problem, steroid therapy at the lowest possible dose may be needed
