Diagnosis of Skin Dog Problems

Diagnosing skin dog conditions is one of the biggest challenges faced by dermatologists and one of the top reasons for visiting a veterinarian among all canine diseases. The reason is that the skin is the largest organ in the body and also the one organ that is most exposed to the environment. Because it is a barrier between infection, parasites, injury and the body, it frequently has observable clinical symptoms such as lesions, lumps, bumps and wounds.



Our goal with this page is to get you to the information you need as a dog owner to start to solve the mystery of what is causing a dog skin problem.

Where to Start Your Dog Skin Investigation

An excellent place to start is the Dog Health Guide section on dog skin.  The site contains hundreds of pictures of skin dog conditions.  You can start by matching the pictures to the symptoms seen on your dog.

Dog skin allergy and dog skin infection (bacterial, viral, fungal) are the top two reasons for a canine skin condition.

The age of the dog and sex can also be helpful indicators. For example, younger dogs are prone to disease such as dog acne, juvenile pyoderma (puss filled skin bumps or pimples), and ringworm. Middle age dogs and young adults often get dog skin problems such as seborrhea (skin faking or dry skin), hormonal problems, and dog skin allergies.

Puppy Skin Juvenile Pyoderma

Puppy Skin Juvenile Pyoderma – Source: Washington State University

Before You Visit a Veterinarian for a Skin Dog Condition

The moment you observe any medical changes in your dog, start to keep a daily diary for your veterinarian. Note any changes in your dog’s behavior, wait, energy levels or appetite. Take pictures when a skin lesion starts to appear so that your Vet can see lesions before they grow and spread on the body.  The reason for this step is that many skin diseases look the same during the later stages.  Recording skin events early improve the odds of quickly achieving a specific diagnosis.

If you got your puppy or dog from a breeder, it might pay to contact them to see if the parents or other siblings have suffered from a dog skin disorder.

What to Expect when Visiting a Veterinarian for a Dog Skin Diagnosis

Like human skin diseases, a veterinary dermatologist needs to be part Sherlock Holmes with different causes eliminated on the path to reaching a specific diagnosis. There are four basic steps in the diagnostic process:

  1. History of the patient: a review of your dog’s life including diet, outdoor/indoor habits, changes in grooming, other pets in the home etc. For example, symptoms that start in the spring are probably a seasonal allergy. Symptoms that occur near the tail and when their are other pets in the home indicate a flea allergy or infestation.

    Dog skin allergy atopic dermatitis

    Dog Skin Allergy Atopic Dermatitis – Source: Washington State University

  2. Physical Examination: to see if the condition of the dog provides any clues. Your vet will observe small signs which include how your dog walks into the examination room, energy levels, and any scratching or itching.. The vet will touch the dog’s entire body, since symptoms such as tumors under the skin could be the cause of skin conditions elsewhere on the body. The asymmetry of the lesions (shape and location), can indicate if the problem is hormonal, which is the case when lesions are the same (size, location, shape) on both sides of the chest, or localized, which means that only one part of the body is affected. The vet will also try and determine if the condition is primary, which means that it directly appeared due to the condition, or secondary, which means that problems such as dog scratching a skin dog itch caused a problem such as a bacterial infection. Even if you solve the “secondary problem” which in this case is infection, you still need to understand why the primary issue, dog itching, is occurring.
  3. Lab and Office Tests: skin scrapings, blood tests and biopsy are all helpful diagnostic tools. Skin scrapings are pretty much standard procedure, with the vet looking at samples taken under a microscope. It will be evaluated for problems such as mites that lead to issues such as scabies. A skin biopsy or sample is taken and sent to a lab when problems such as neoplasms (tumors, cancer) are suspected or need to be ruled out. In the office a special lamp called a “Woods Lamp” is used to detect fungal infections such as Ringworm.

    ringworm dog face

    Ringworm on Dog Face – Source: Washington State University

  4. Therapy Trials: if a cause of the skin dog issue is suspected, a veterinarian will start treatment to see if any improvement can lead to a diagnosis. This approach is sometimes necessary since tests may not pick up on issues such as mites, since they would need to be present in the specific skin sample taken in order to be diagnosed.

Diagnosing Dog Skin Allergy

If a veterinarian suspects skin dog allergy as the cause of the problem, then the veterinarian has two types of tests at his or her disposal.  This includes an intradermal skin test and blood tests. In intradermal skin dog allergy testing,  the hair is clipped from the side of the chest where small amounts of allergen are injected into the skin. If a skin reaction is seen at the site where an allergen was injected, then the dog is considered to be allergic to that substance. Blood tests can also be used to detect allergens using what is called an antibody test. Note that for intradermal testing a dog sometimes needs to be tranquilized. Once the allergen is identified, strategies to keep the dog away from an allergic trigger can be established.

dog skin allergy test

Dog Skin Allergy Test – Source: Washington State University

Dog Food Allergy and Elimination Diets

If allergy testing indicates a dog food allergy, then the veterinarian will recommend an elimination diet. Here the goal is to pare the diet down to one simple protein (duck, chicken) and one simple carbohydrate (rice).  It takes 3 to 12 weeks of being on an elimination diet before results are seen.  If the skin condition clears, then the diagnosis will be confirmed as a dog food allergy. Ingredients will slowly be added back into the diet until the ingredient which was causing the allergy results in skin symptoms. At this point you’ll know exactly what needed to be eliminated from the diet.

Understanding Dog Skin Infections

Dog skin infections are usually bacterial, and are the second leading cause of dog skin problems after allergy. Symptoms are referred to as pyoderma, which describes a skin bump or dog skin pimples filled with pus. Infection can spread internally, so it is important to seek treatment for infection.  Other symptoms include hair loss or a thinning coat.

When a dog is suffering from a bacterial infection it indicates that the immune system is not operating properly or another condition which allowed bacteria to enter the skin. For example, dog fleas can cause an allergic reaction or mites which cause problems such as dog mange or scabies, can cause dog itching and scratching which results in infection.

Dogs suffering from hormonal problems also frequently get bacterial infections. These diseases are known as Cushings Disease/syndrome.

Causes of Dog Skin Pimples Lumps and Bumps

It’s often the dog skin lumps, bumps and pimples which lead to a visit to the vet. Here’s the most common causes of these problems.

  • Injury from bites or scratching
  • Ingrown hair
  • Parasitic diseases such as scabies and dog mange (mites) and fleas
  • Dog allergies (inhaled which is called atopy, food, flea)
  • Abnormal skin function (dog skin flaking, which is called seborrhea)
  • Metabolic Disorders (liver function, diabetes)
  • Canine Auto immune diseases (pemphigus, lupus)
  • Cancer or Tumors (called neoplasia)
  • Nutrition (dietary issues)
  • Environmental Problems (humid weather, hot weather)
  • Sensitivity to bacteria
  • Steroid use that affects the skin
  • Ringworm (called dermatophytes)

Reaching a Dog Skin Diagnosis

Based on the results from these skin dog related investigative steps,  the veterinarian should have enough information to make a preliminary diagnosis.  Often treatment will be started at this point, with confirmation of the diagnosis based on how well the dog responds to the specific treatment protocol related to the ailment identified.  The goal of course is to reach a definitive diagnosis.

The problem is that many skin disease look the same. For example, the chronic skin diseases sarcoptic mange and allergic dermatitis look the same during the later stages of the disease. It will be helpful to your vet for you to record how a skin disease progresses over time, since the initial location is a sign of what problem is being treated.  As implied here, you are also responsible for recording how any prescribed treatment is working.  If you don’t see results in the time indicated by the vet, it probably means that the initial diagnosis was not correct. If your dog is improving, identifying the reason for the improvement is also tricky as you may be using a combination of therapies such as prescription medications, medicated shampoos, supplements and other treatments.

If all else fails, see a specialist such as a veterinary dermatologist. You can also review the many charts available here on dog skin problems  to see if you missed anything when investigating your dog’s skin condition.

Related Articles:Dog Dry Skin
Dog Skin Infections

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