Itchy Dogs! Part II
May 1, 2019
Now that we know the basics about atopy, let’s talk about treatment. It is very important to think of atopy as something we manage, because this is a lifelong problem that can never be truly cured. Our goals are to keep your dog comfortable with minimal itching and infrequent secondary infections, but it is very rare that we can eliminate symptoms altogether.
Regardless of what else we do, it is very important to treat any active bacterial or yeast infections. Untreated infections increase itchiness, discomfort and inflammation. Depending on the location and severity, treatment may include topical and/or oral antibiotics, antifungals, and/or medicated shampoos. It is also important to understand that occasional recurrences of secondary infections are common and will need to be treated as they occur.
The non-drug treatment options include bathing, hyposensitization, and omega-3 fatty acids. These may not eliminate the need for medications, but may reduce the dose and frequency of medication needed. For example, my dog Squash: Before starting hyposensitization and regular bathing he took daily Apoquel and had 1-2 skin infections per year requiring treatment with antibiotics. Since starting hyposensitization and regular bathing with an antibacterial shampoo, he gets 1-2 Cytopoint injections per year and has not had any skin infections requiring antibiotics (knock wood!).
Regular bathing removes allergens from the skin and haircoat so there is less stimulation of the immune system. Medicated shampoos can keep populations of yeast and bacteria in check and nip brewing infections in the bud. The frequency and specific shampoo will vary from individual to individual, but during your dog’s allergy season once a week would be reasonable. It is rare (though possible) that bathing alone will manage a dog with atopy, but it should always be part of the plan.
Most medications suppress the immune system to reduce itching and/or inflammation. Hyposensitization (“allergy shots”) works differently by changing how the immune system reacts to allergens. Very tiny, gradually increasing levels of allergens (determined by allergy testing) are periodically injected under the skin. Over time, the immune system is desensitized (“gets used to” allergens) and reacts less and less.
I am a huge fan of hyposensitization and cannot say enough good things about it after having two dogs with atopy for whom it has been life-changing. The success rate is high, with improvement seen in about 75-80% of dogs. In an ideal world, every dog with atopy would start hyposensitization, but the big disadvantage is the cost. Referral to a veterinary dermatologist, testing, allergens, and supplies add up to a substantial up-front expense compared to medication (although ongoing maintenance costs are comparable).
Omega 3 fatty acid supplements can help interfere with the production of inflammatory chemical messengers in the skin. They are not usually powerful enough to eliminate the need for other treatments altogether, but may allow lower doses or less frequent use of medication. Coconut or olive oil are not rich enough in omega 3s, there are specific supplements that should be used. My favorites are Welactin and Grizzly Fish Oil. They can take 2-3 months to show their full effects.
Next, medications generally fall into one of three categories: Antihistamines, general immune suppressants, and the newer more targeted products Apoquel and Cytopoint.
Over the counter antihistamines (such as Benadryl) may help some dogs. They suppress release of histamine, one of the chemical messengers that triggers allergy symptoms. Antihistamines are readily available without a prescription, inexpensive, generally have mild or no side effects, and are safe for long term use. The disadvantage is that they are only effective for about 20% of dogs with atopy. When using them, it is very important that the antihistamine is the only active ingredient; never use multi-symptom products that contain pain relievers, decongestants, etc.
For a long time, cortisone-like steroids (prednisone, methylprednisolone) and cyclosporine (brand name Atopica) were the cornerstones of managing atopy in dogs because they are very effective and we did not have other choices.
Prednisone is inexpensive, rapidly effective, and has potent anti-inflammatory effects. However, rather than targeting allergic responses specifically, it suppresses the immune system generally which can make pets susceptible to infections. It also has a number of side effects, especially with long term use. In the short term, these are usually limited to increased thirst, hunger, and urination. In the long term, because prednisone belongs to the group of steroids that are involved in the body’s stress and “fight or flight” responses, we can see more serious effects such as breakdown of muscle and connective tissue, stomach ulcers, changes in skin and haircoat including delayed healing of wounds, increased blood sugar, and changes in the liver. While we still often use prednisone short-term for immediate relief of itching, it is less common to use it in long term management.
Cyclosporine is a non-steroid general immune suppressant that inhibits some of the cells and chemical signals involved in the allergic response. Its main advantage is that for long term use, it has fewer side effects than prednisone and it is less expensive than some of the newer drugs. However, it may slightly increase the risk of infections and certain cancers with long term use.
The newest options for managing atopy in dogs have more targeted effects designed to interfere with the chemical messengers involved in the allergic response while leaving the rest of the immune system alone. This group includes Apoquel and Cytopoint. Because these are newer and still patented, they are more expensive than previous options but very effective and safer for long term use.
Apoquel inhibits chemical messengers called JAKs that are part of the pathway that creates the sensation of itchiness. Apoquel works quickly, is effective in most dogs, and can be used long term. We rarely see serious side effects but it can cause stomach upset, possibly increase the risk of infections, and may allow pre-existing cancers to worsen. Rarely, it can cause anemia so blood counts should be periodically monitored. More information can be found at http://www.apoqueldogs.com
Cytopoint is the newest option and works differently from any of the others. It is not a drug, but breaks down IL31, one of the main chemical messengers that creates the sensation of itchiness. Strictly speaking, it can be thought of as an antibody against IL31. Because it is so specific in its action, the chance of side effects is very low. It is given by injection under the skin. About 80% of dogs will show improvement within 24 hours of injection and it typically lasts for 4-6 weeks. More information is available at http://www.cytopoint4dogs.com
That was a lot of information! The main takeaways to keep in mind are:
- We cannot cure atopy, only manage it.
- There are many options for management, many of which can be used together. These vary in cost, side effects, and administration, and there is no “one size fits all” treatment.
- Only hyposensitization changes the reaction of the immune system, other treatments suppress itch and/or inflammation. However, it does not necessarily eliminate the need for other treatments.
- Bathing your dog regularly can help tremendously when combined with other treatments.
As always, if you have any questions please feel free to contact the clinic and speak to one of our doctors.
Karen Christopherson DVM CVA