The most common reason we take our dog to the veterinarian besides getting their shots is a skin disease. Hair loss and excessive scratching are the most common manifestations of canine skin disease. To successfully diagnose and treat your dog for scratching and hair loss, your veterinarian will probably need to perform some basic laboratory testing.
There are many different conditions that can cause skin disease, but the skin of the dog reacts to a disease in a limited number of ways. As a result, many of the diseases that cause skin problems in dogs cause similar symptoms that look identical to one another.
A HISTORY OF YOUR DOGS HEALTH
Your veterinarian will begin the search for the cause of your dog’s hair loss by asking you basic questions. Keep track of your dog’s health history so you can answer these questions.
WHEN DID THE HAIR LOSS START?
IS YOUR DOG CONSTANTLY SCRATCHING?
Has your dog suffered from similar problems in the past and when?
- Is your dog currently taking any medications?
- Herbal supplements?
- What is your dog eating at meals?
- What’s his environment like?
- Are there symptoms other than scratching or hair loss?
- Are there other pets in the home?
- If there are, are they suffering the same problems?
- Are family members noticing any abnormal skin lesions?
THE PHYSICAL EXAMINATION
Your dog will have a complete physical examination from the head to the toes, looking of evidence of parasites ( such as fleas, ticks, and lice ), skin lesions ( such as red spots, scabs, and sores ) and overall health. The exam will include the eyes, ears, teeth, and other body parts as well. This is because skin disease can sometimes be a manifestation of disease in an internal organ system or other body parts.
With history information and a physical examination, your veterinarian will be able to determine which diseases are most likely causing the hair loss and itching for your dog. The results will also help in determining which diagnostic tests should be performed.
WHAT TESTS ARE USED TO DIAGNOSE THE SKIN DISEASE?
- Skin scrapings to look for evidence of the mites that cause mange.
- Skin cytology looking for evidence of yeast and bacterial infections in the skin
- Fungal cultures that check for ringworm ( not a worm ) and other fungal infections
- Skin biopsies if skin cancer or other serious skin disease is suspected
- When in cases where your veterinarian suspects that a more systemic ( whole-body ) disease is causing your dog’s skin problems, a blood screening may be recommended.
- A blood screen usually consists of a complete blood count ( CBC ) and a chemistry profile.
The complete blood count looks closely at the red and white blood cells in a blood sample. The blood chemistry profile allows the evaluation of kidney function, liver enzymes, protein levels, and electrolyte levels. In dogs with skin disease, blood screening may also include tests that evaluate the thyroid function, including total T4, free T4, and/or thyroid-stimulating hormone ( TSH ).
DIAGNOSING SKIN DISEASE WITH FLEA CONTROL
If your dog is scratching and losing hair, one of the first things your veterinarian will probably recommend is a reliable form of flea prevention if you are not already using flea control. This is because fleas can be notoriously difficult to find on dogs, even when fleas are the main trigger for the condition. If fleas are not the cause, controlling them is still important, as any fleas are likely to make an original skin problem a lot worse.
IS A FOOD ALLERGY THE PROBLEM?
When the flea situation has been remedied and ruled out as the cause of the itching, your veterinarian may recommend doing a food trial. A food trial involves feeding your dog a special diet for two months to bring your dog’s immune system back to a non-reactive baseline.
The special diet is called a novel protein diet or a hydrolyzed ( chemically digested ) diet; it is devoid of all protein and carbohydrate ingredients that are the most common triggers of food allergy in dogs. Normal protein triggers are beef, milk products, chicken, and eggs, while common carbohydrate triggers are wheat, corn, and soy.
Once the dog’s immune system has calmed down, these ingredients can be tried one by one to see if they induce skin reaction. If so, itching symptoms will appear within about three days. Most food-allergic dogs will show sensitivity to more than one kind of protein or carbohydrate.
ALLERGY TESTING AND IMMUNOTHERAPY (HYPOSENSITIZATION)
When other causes of hair loss and scratching have been ruled out and if your veterinarian is relatively certain that your dog is suffering for atopy ( an immune system that is sensitive to something in your dog’s environment ), then allergy testing may be recommended.
An allergy testing can determine which substances your dog is allergic to. The treatment for acquired allergy is immunotherapy, also called hyposensitization. This involves injecting a solution of the allergen ( the substance causing the allergy ) into your pet over some time in an attempt to train your pet’s body to not respond abnormally to the allergen.