Canine Atopic Dermatitis Therapeutic

Canine atopic dermatitis is a very common allergic skin disease in dogs. In fact, some dermatologists estimate that up to one third of the dog population is affected. The primary symptom of atopic dermatitis is itching which can result in hair loss and skin infections and reduced quality of life. Like hay fever, atopy is triggered by seasonal pollen and other airborne allergens.

Canine Atopic Dermatitis Therapeutic (CADI) is a new therapy introduced by Zoetis that helps reduce the itching in atopic dogs. It is a monthly antibody injection that mimics the dog’s immune system to help neutralize the main cause of itching in this population of dogs.

In a study of CADI it was found to reduce itching within one day after a single injection, control itching for a full month, and improve skin condition caused by atopic dermatitis.

I recently treated Tess, my 10 year old German Shepherd with chronic atopic dermatitis, and the response has been amazing. She has not been this itch-free and this comfortable in years.

Carl D. Anderson, DVM

Should I Spay or Neuter my Dog and If So, at What Age?

I recently attended a seminar put on by the WSVMA on this topic. The panel of speakers included two boarded veterinary surgeons, one boarded veterinary behaviorist and one veterinary reproductive expert. At the end of the day I realized there are no easy answers to these questions, and the decision as to when or whether to spay and neuter needs to be an informed decision made by the dog owner.

Here are some facts which came to light during the discussion. Keep in mind that the knowledge in this area is based on retrospective studies, some of which have a limited sample size.

  1. Dogs that are spayed or neutered generally live longer. Of course it may not be that the spaying or neutering is causing the increase in longevity. It could be that dogs that spayed or neutered dogs, on average, receive better care during their lifetime.
  1. Certain cancers are more common in dogs that are spayed or neutered. Examples are bone cancer, hemangiosarcoma, lymphoma, transitional cell carcinoma, and mast cell tumors. The incidence of these tumors is somewhat breed related. For example, osteosarcoma in the general dog population has an incidence of 0.2%, but in Rottweilers and other large breeds the incidence is much higher. So in Rottweilers a 2-3 fold increase in incidence off osteosarcoma due to spaying or neutering is much more significant than it is in the general population. Some of the findings for specific breeds are complex. For example, the incidence of hemangiosarcoma in Golden Retrievers spayed after 12 months of age is 4 times that of unspayed females or females spayed prior to 12 months of age.
  1. Mammary (breast) cancer is almost eliminated if spaying is done prior to the first heat cycle and is significantly reduced if performed prior to the second heat. Dogs spayed after the second heat have a 26% chance of developing mammary neoplasia during their lifetime, and 50% of these are malignant. Compare this to the low incidence of osteosarcoma which is 0.2% of the general population. A 2-3 times increase of a very low incidence cancer is still rare.
  1. It appears that there is a greater incidence of orthopedic disease in spayed and neutered dogs. The most common conditions affected are cranial cruciate ligament injury (CCL) and hip dysplasia (early arthritis of the hip joint). Most of these studies compare dogs spayed or neutered before 5 months of age to ones spayed or neutered after twelve months of age. It is felt that waiting to spay or neuter until after the dog is finished growing should reduce the negative effect. However, it is not clear when exactly the growth plates close. In general it is felt that in small to medium breeds the growth plates close prior to a year of age, but in large breeds it could be over a year.
  1. There appears to be no real health advantage to neutering male dogs except preventing certain forms of prostate disease. Prostate cancer is higher in neutered dogs. There may be some behavior benefits to neutering but one study indicated that early neutering is associated with certain behavioral problems e.g. separation anxiety, aggression.
  1. Spayed and neutered dogs appear to be at an increased incidence of hypothyroidism and other immune mediated diseases.
  1. Spayed dogs have a greater incidence of urinary incontinence. This is particularly true when spaying is done prior to three months of age.
  1. Uterine infection (pyometra) has a significant incidence in dogs that are not spayed. It is estimated that close to 23% of unspayed female dogs will develop pyometra by 10 years of age. And pyometra is a life threatening condition that requires early intervention.

In summary, it appears that the incidence of many cancers with a low incidence are increased by spaying and neutering, and one form of cancer (mammary cancer) with a high incidence is increased by failure to spay prior to the female’s second heat cycle. Unspayed dogs have a high risk of developing a life threatening uterine infection.

Spayed and neutered dogs may have an increased risk of developing certain immune mediated diseases, e.g. hypothyroidism. There are conflicting reports in the literature regarding the effects of spaying and neutering on behavior, but some studies indicate an increase in certain behavior problems in dogs spayed or neutered prior to 6 months of age. Other studies indicate that neutering male dogs may help with certain behavioral problems such as aggression, urine marking, and mounting behavior.

So there is really no clear cut answer. One of the panel participants, the reproductive expert, recommended ovarian sparing hysterectomies for female dogs and vasectomies for male dogs. But the ovarian sparing hysterectomy is a complicated surgery and does not address the mammary cancer issue, and there are frequently problems related to vasectomies in male dogs.

Several of the panelists felt the best summary article in this area for clients to read is “Determining The Best Age At Which To Spay of Neuter” by Margaret Root-Kustritz, DVM, PhD.

The conclusion of this paper reads:

“For female dogs, the high incidence and high frequency of mammary neoplasia, and the significant effect of spaying on decreasing its incidence make ovariohysterectomy prior to the first heat the best recommendation for non-breeding animals. The demonstrated increase of urinary incontinence in bitches spayed before 3 months of age and the possible effect of CCL injury in bitches spayed before 6 months of age, suggest that spaying bitches after 6 months of age but before their first heat cycle is most beneficial. For bitches of breeds predisposed by ovariohysterectomy to highly malignant tumors and for breeding animals, spaying at a later age may be more beneficial.

For male dogs, castration decreases incidence of disorders with little health significance and may increase incidence of disorders of much greater health significance. For non-breeding animals, evaluation of breed and subsequent predispositions to disorder by gonadectomy should guide when and if castration is recommended.”

Carl D. Anderson, DVM

Immunotherapy Treatment for Dog Allergies

A recent blog post concerned itself with the very common problem of allergic skin disease in dogs. I am happy to report that we are now offering immunotherapy (desensitization) as a treatment for dogs with challenging skin allergies caused by airborne particles such as pollens, molds, and household mites. If your dog is a candidate we would draw a blood sample and submit it to a lab which then identifies the pertinent allergens. A specific treatment is then formulated based on the results of this test. There are two ways the treatment can be administered. (1) Drops are placed under your dogs tongue.  (2) By an injection under the skin (allergy shots).  Most clients prefer the oral drops.

The goal of immunotherapy is to reduce or eliminate the symptoms of your dog’s skin allergy. As noted in the previous blog, these symptoms include excessive scratching, biting, licking feet, ear infections, and inflamed reddened skin.  Initially medications to control itching and infection are used along with the immunotherapy. Results vary but frequently the dog will be more comfortable and require less medication over time to control itching. Immunotherapy is generally a long term and/or possibly a lifelong process. For more information regarding the Heska Allercept program we participate in, click here for their website.

Allergic Skin Disease in Dogs

Allergic skin disease is one of the most common reasons for veterinary visits in dogs. Some dermatologists estimate that up to 40 percent of the dog population will develop some form of allergic dermatitis during their lifetime. For owners this condition can be very frustrating as there often is no definitive cure, and treatment can be ongoing throughout their pet’s life. So it is important for dog owners to have some knowledge concerning their dog’s skin allergies.

First of all, the three most common forms of skin allergies in dogs are flea allergy dermatitis, food allergy and atopic dermatitis.

With flea allergy the dog becomes sensitized to a protein in flea saliva. The area of the body most affected is the rear half of the dog, especially the rump and down the back legs. Luckily, with the introduction of effective topical and oral flea control medications, we see a lot less of this condition than in the past.

Dogs with food allergy become sensitized to a protein in the diet. This could be chicken, egg, beef, lamb, wheat etc. The most common areas affected are the ears and feet, but over time large areas of the body can become involved. A majority of dogs with food allergy also have some bowel problems. Food allergy is diagnosed by introducing a novel protein diet, or a hydrolyzed diet where the protein is broken down so the body does not recognize it. If the itching resolves then the offending food is fed again to see if itching returns. This is done because a change of season or other factors might be what is responsible for reduced itching. Food allergy is not as common as many people think.

With atopic dermatitis the offending allergens are often airborne and include pollens, molds and house dust mites. As with food allergy, the ears and feet are commonly involved. Other areas of involvement are the face, axilla, groin, and in general hairless areas of the body. Unlike food allergy, symptoms of atopy almost always begin in the first 2 years of life. One way to look at atopy is “hay fever of the skin.” In the beginning most atopic dogs exhibit symptoms seasonally, but may have symptoms to some degree year round; they may be worse in the spring and the fall.  Atopic dermatitis is the most common form of allergic dermatitis we see in dogs.

Whatever the form of allergy, the result is itching. And this leads to biting and scratching, which frequently results in skin infections with bacteria and/or yeast. The skin infection, in turn, makes the itching worse. So we have a vicious cycle of itching, scratching, infection, followed by more itching. Changes of the skin in the ear canal caused by atopic dermatitis and food allergy often result in ear infections. In fact, the most common cause of ear infections in dogs is allergy.

So what can we do?

  1. Since sarcoptic mange (scabies) often mimics both food allergy and atopic dermatitis, in severe cases it is prudent to rule out scabies. This is difficult to do with skin scrapings as the mites are very difficult to find. So often we end up treating with the topical flea medication Revolution, since it will treat this form of mange.
  1. We need to determine if secondary infection is present. If so this needs to be treated by antimicrobials or topical medications or both. Many dogs will need weekly medicated baths to prevent recurrence of infections.
  1. If the itching is year round a food trial is warranted.
  1. Flea control. Dogs with allergic dermatitis of any variety cannot tolerate flea bites, so they should be kept on year round flea control medication. Two excellent flea products are Bravecto, a pill given once every 3 months, and Revolution, a monthly topical spot on treatment. Both of these are unaffected by frequent bathing.
  1. Frequent bathing with a hypoallergenic shampoo. This can help to rinse off airborne allergens and reduce itching. An example of a hypoallergenic shampoo is Vet Solutions Aloe and Oatmeal.
  1. Fatty acid supplementation. Fish oil capsules containing Omega 3 fatty acids can help reduce itching.
  1. Many dogs will also need medication to help control itching. Our choices here is corticosteroids (e.g. prednisone), antihistamines (e.g. hydroxyzine, diphenhydramine), cyclosporin (Atopica), and a new medication Apoquel. Unfortunately, antihistamines are usually not very effective but it can be helpful to give diphenhydramine (Benadryl) at bedtime as it helps with sleep. Probably the most significant advance in medication for allergic skin disease over the past 20 years is the drug Apoquel. We have not seen side effects with this medication, and we can use it either short term or on a long term basis. The problem has been supply as this drug is difficult to manufacture and the demand has been very high. The supply is getting better and we are now placing new patients on this medication.
  1. Immunotherapy for atopic dermatitis. In severe cases, allergy testing by either skin tests or blood tests can be performed; the goal is to develop a vaccine to desensitize the dog. The vaccine can be given by injection or an oral formulation. This can be very helpful but is a long term treatment and results may take some time. Expect more on this in a future blog posting.

Carl D. Anderson DVM