Dermatitis or The Itchy Dog

As the weather becomes colder here in Southern Ontario I am seeing fewer itchy dogs, however there are those who do not find relief from this annual freeze.  The itchy dog is one of the most frustrating types of patients in my profession.  The dog is uncomfortable and finds it hard to find relief and the owners are concerned about their pet.  It seems as though no matter what they do, their pet is not getting better and often he is getting worse.  

These red itchy dogs are said to have “dermatitis”.  This is a word derived from latin and  can be broken down into two parts; “derm”, meaning skin and “itis”, meaning inflammation.  So literally these dogs have inflammation of the skin.  Although it sounds like a fancy diagnosis it is really nothing more than a description of a poor uncomfortable dog.  

Skin becomes red and swollen.  

Hair is lost.  

Sores can appear in the form of abrasions, pustules or scabs. 

The skin is an organ and includes the inside of the ears.  Thus ear infections are technically a type of skin infection as well. The skin acts as a barrier to prevent things from the outside getting in.  The skin is bombarded with proteins of all sorts every day.  These include pollens, dust mites, bacteria, yeast and many other tiny particles.  Sometimes the barrier is broken down for some reason, such as a cut or scrape and at other times an individual will over-react to a specific protein.  When this happens the skin then calls in inflammatory mediators which result in the inflammation we see as red itchy skin.  

Something has caused the skin to react adversely and the question then becomes what is causing the inflammation.  The most common causes of inflammatory reactions of the skin include:

1. Atopy, environmental allergies, flea bite sensitivity or contact sensitivity, 

2. Food Allergies or Sensitivities

3. Infectious causes - 

1. parasites
2. bacteria
3.  yeast
4. fungi

These conditions may exist alone or in any combination with each other and often it can be very difficult to determine which disease process(es) are at work.  

When your veterinarian sees your dog she may need to carry out many tests to help determine what the cause of your dog’s dermatitis is.  These tests may include: 

1. Skin Scrapings
2. Cytology or tape preps
3. Hair plucks
4. Skin biopsies
5. Bacterial cultures and sensitivities
6. Fungal cultures
7. Allergy testing
8. Food elimination trials.  

Treatments for Dermatitis depend on what the underlying cause is.  It is not uncommon for multiple treatments to be needed together.  

The best treatment for Atopy and food allergies is avoidance but this is not always possible and so sometimes hyposensitization is useful.  Anti-inflammatories may be required to decrease the inflammation of the skin.  Infectious causes need to be treated with the appropriate medication depending on the infectious agent and what it is sensitive to.  Omega fatty acids and other supplements can help to improve the integrity of the skin, thereby helping it to resist the inflammation.  

Treatments may include: 

1. Avoidance
2. Antihistamines
3. Hyposensitization
4. Antibiotics
5. Anti-fungals
6. Shampoos
7. other topical treatments
8. Omega fatty acid supplements
9. Anti-parasitic medications

Sometimes one type of therapy is all that is required but in most cases multiple therapies working together are often needed to treat the patient.  It is also true that in many cases we are looking for control of the disease, rather than a cure.  If you are living with an itchy dog it is important that you work with your veterinarian to help your pet.   You may need patience and persistence to see results.