Diseases of the Skin and Ears

The Allergy, Skin and Ear Clinic for Pets provides you with some insight on common dermatological and allergy problems common in dogs and cats.

ATOPIC DERMATITIS (Allergic Skin Disease)

An allergic dog prior to treatment

Post - Treatment

Atopic dermatitis is a pruritic (itchy) skin disease of dogs and cats. In atopic dermatitis, an allergic reaction occurs when an animal inhales airborne substances (pollen, house dust) or ingests (eats) a substance to which they are sensitive. The allergic reaction causes the animal to rub, lick bite, or scratch. Unlike man, animals with atopic dermatitis only occasionally cough, sneeze or get asthma. Instead, they itch. The itching may be localized to certain areas or may be over their entire body. Usually the feet, face, ears, armpits and front legs are affected. This is in contrast to flea allergy where the rump, tail, groin and thighs are affected. About 1/2 the pets with atopy will also be allergic to fleas and so will have symptoms of both diseases.

Atopic dermatitis due to food reactions can be cured, while those due to airborne substances can't be cured, but in most cases it can be controlled. Usually, cortisone-type drugs (steroids) are used. They are very effective anti-inflammatory, anti-itch medications. The problem with steroids is that they have more side effects (excessive drinking, urinating and eating along with increased susceptibility to infection) than other treatments. If used long term without supervision, it may decrease your pet's longevity. Unfortunately, it may be the only treatment that will control your pet's symptoms.

If you do not want your pet on long-term steroids, or if he cannot tolerate them, there are alternatives.

Antihistamines in conjunction w/essential fatty acids (EFA's) will control 10-25% of animals with atopic dermatitis due to airborne allergens. They have far fewer side effects (only grogginess) than steroids. EFA's work better in combination w/antihistamines than either product by themselves. There are no side effects to EFA's, but they may take up to 60 days to be effective. These products, however, do not help pyodermas (bacterial skin infections), Malassezia infections (yeast infections), otitis externa (ear infections), cutaneous adverse food reactions or flea allergies.

Cyclosporine is another alternative to steroids. It works by suppressing the immune system, but in a safer manner than steroids. It is effective 40-50% but must be given life long and like antihistamines is not effective for a pet with pyodermas (bacterial skin infections), Malassezia infections (yeast infections), otitis externa (ear infections), cutaneous adverse food reactions or flea allergies.

Apoquel (chemical name oclacitinib) is an oral medication licensed for the treatment of both acute allergies and chronic atopy in dogs >12 months of age. It can be used instead of steroids to treat dogs with occasional seasonal pollen or flea allergy flares, and to control itch in allergic dogs while the underlying cause of the itch is addressed (ie. while a hypoallergenic diet trial is started in food allergic dogs, or to control itch in atopic dogs while allergy desensitization therapy has time for effect). This drug is a janus kinase inhibitor, similar to the human rheumatoid arthritis medication Xeljanz. Apoquel acts to reduce production of inflammatory allergic proteins and also to reduce the sensation of itch transmitted by nerves, which no other drug does. It is intermediate in cost between steroids and cyclosporine, and acts very rapidly (within hours) to reduce itching. It is given twice daily for 2 weeks, then once daily, and in both short term and longer term (2-3 year) studies appears so far to have very few side effects (occasional GI upset). Since this is a relatively new drug, and it does affect the immune system, regular examinations and lab work are still recommended.

Canine Atopic Dermatitis Immunotherapeutic is our newest therapy that helps reduce clinical signs of atopic dermatitis so that your dog can stop scratching. This is a new type of medication called an antibody therapy, designed to target the itch at its source. It mimics the natural immune system of your dog to help neutralize the main cause of itch in atopic dermatitis. Canine Atopic Dermatitis Immunotherapeutic is an injection given every 4-6 weeks by your veterinarian.

Allergen-specific immunotherapy (ASIT) is the ONLY method that is currently available to help IMPROVE the health of the immune system (vs MASKING symptoms). ASIT involves giving a series of injections containing specific airborne (not food) antigens to which your pet is sensitive. In order to determine YOUR pet's SPECIFIC airborne allergy, intradermal testing is performed. Intradermal testing is a technique in which a small amount of airborne allergens are injected into the skin. The skin is then evaluated for any reactions to determine which airborne allergens affect your pet. Once we identify the allergens, you can try avoiding them. However, in the vast majority of the cases (99%) avoidance does not work. Allergen-specific immunotherapy makes it possible to desensitize your pet to these airborne allergens.

At the Allergy, Skin and Ear Clinic for Pets, 60-70% of the cases of atopic dermatitis due to airborne allergens respond to allergen-specific immunotherapy (either needing no other medication or less potent medication than previously). Allergen-specific immunotherapy stimulates your pet's own protective mechanism (immune system), which stops the allergic reaction from occurring. You will need to give an injection every 7-21 days for the LIFETIME OF YOUR PET. Because we must depend on the immune system for allergen-specific immunotherapy to work, it may take 6-12 months for them to be effective. Pets with atopic dermatitis are prone to secondary skin infections, ear infections, and Malassezia (yeast) infections and frequently have sensitive skin. Any skin infection, irritating substance, or fleas will aggravate the allergic condition.


A dog with generalized Demodex prior to treatment

Post treatment- wow!

Demodex prior to begining treatment

2 months after treatment began!

Generalized demodicosis is a non-contagious disease of dogs and a potentially contagious disease in cats that is associated with an uncontrolled increase in the number of Demodex mites within the hair follicles. The mite itself is a normal inhabitant of all animals. However, some cats and dogs cannot control the numbers of mites and the mite population grows out of control. This inability to control mite population probably relates to an abnormal immune system.

Abnormalities of the immune system have many causes. Some examples are; An inherited weakness, Hypothyroidism (low thyroid hormone), Excessive cortisone production or use, Cancer, or Unknown causes.

When generalized demodicosis occurs in young dogs (<6 months) it is probably an inherited condition (even though the parents may not have exhibited the disease). In cats and older dogs, it may result from internal diseases affecting the immune system. Testing to help find the cause is very important.

Localized demodicosis occurs as one or more small, round, red, scaly, occasionally itchy areas of hair loss. This form of the disease usually resolves with just topical treatment, but in dogs it may progress due to an inherited weakness. Any area of the body may be affected, however the face, forelegs and feet are the most commonly affected areas in dogs and cats (cats also tend to have the ventral abdomen affected).

In dogs, a chronic demodectic pododermatitis affects the paws and may occur with or without the rest of the body being affected. This is an extremely difficult form to treat or cure. Many times demodicosis is complicated by a secondary skin infection. In these cases, cultures and long-term antibiotics are needed.


AISD results from a disorder of the immune system and the skin. Normally the immune system only attacks "foreign" invaders (bacteria and viruses). In AISD, the animal's body recognizes its own skin as "foreign". As a result of this abnormal immune response, the skin is attacked and damaged. In a sense, the animal is trying to reject its skin, just as it would try to reject a viral or bacterial infection.

Why does the animal's immune system recognize its own body as foreign? So far, we can't answer that question. Various explanations have been proposed which include genetic, environmental, drug and viral factors. In dogs, there is some evidence for a genetic component, as AISD is seen more commonly in certain breeds (Akitas, Collies, Shelties, Chows and Dobermans). We currently diagnose several distinct syndromes, eg. Pemphigus, pemphigoid, systemic and discoid Lupus Erythematosus.

Most cases of AISD occur in mature animals. The skin lesions first appear as small red spots that rapidly form a blister, then a pustule or pimple, and finally a crust. In most cases, the major lesions noted by the owner are red spots, ulcers and thick crusts (scabs) that form over the spots. The crusts usually start on the nose, around the eyes and on the ear flaps. Lesions may also involve the foot pads, mouth, anus and genitals. Itchiness is variable, as some pets are not bothered at all while others are constantly rubbing and scratching. Other signs commonly noted are depression, lethargy, anorexia, lameness, enlarged lymph nodes and fever.

The definitive diagnosis of AISD should always be made prior to treatment as numerous other diseases can look like AISD. Also, the treatment for these diseases can seriously harm your pet and exacerbate other skin diseases. Therefore, a definitive diagnosis should be made so that the correct and appropriate treatment(s) can be started.

Several tests are necessary to diagnose AISD. Blood tests along with cultures and skin biopsies are needed to diagnose if, and which, AISD is present.

Once the diagnosis has been made, several treatments are available. Treatment involves using different medications that suppress the abnormal immune response and therefore are called immunosuppressive drugs. Each drug available has its good and bad points. They are all very potent agents and can cause serious side effects with chronic use. A baseline blood panel and urinalysis will be done initially and periodically during treatment to monitor for adverse drug effects.

In most cases, pets with AISD can be controlled so that their skin is normal with only rare flare-ups. However, most have to stay on some treatment for life. In addition, there are some cases that can't be controlled with the treatments currently available. At the present time there is not test to determine which dogs will respond to treatment and which ones will not. It may be necessary to try several different drugs or combinations of drugs before you will know whether or not your pet's disease can be controlled.

A dog with Pemphigus.

2 months later!


Malassezia is a non-contagious yeast infection of the skin of dogs. The appearance of the skin varies. Typically we will see at least one of the following lesions involving the face (around the lips), neck, armpits or feet:

  1. Oily/greasy skin

  2. Hair loss

  3. Thickened lathering skin

  4. Scaly Skin

  5. Red skin

Yeast infections may be very itchy. The development of a yeast infection indicates some underlying cause that allowed the yeast to overgrow. Most commonly it has been associated with allergies (atopic dermatitis or food-induced hypersensitivity). Treatment involves a topical medication and/or oral medication for 2-4 weeks.


Pyoderma is a bacterial infection of the skin which may involve different layers. Superficial pyodermas are within the skin near the surface and can often be recognized by the presence of circular crusting lesions or red pimples. Deep pyodermas occur when bacteria invade structures beneath and beyond the hair follicle. This can be recognized in most cases because pus can be expressed from the skin lesions.

Staphylococcus intermedius is considered to be the prime bacterial pathogen of the skin. The bacteria rarely infect normal skin, but can if there are injured or inflamed skin surfaces.

The development of a pyoderma depends upon several factors. The most important is the host's response to bacterial invasion. Some of the more common causes of recurrent or deep pyodermas are:

  1. Drug-induced (i.e. cortisone)

  2. Immune deficiency or depression

  3. Hormonal (i.e. hypothyroid, Cushings disease)

  4. Allergic (pollen allergy, flea allergy, food allergy)

  5. Parasitic (i.e. demodicosis, scabies, fleas)

  6. Keratinization abnormalities (i.e. Seborrhea)

  7. Immune-mediated (i.e. pemphigus, Lupus)

  8. Fungal (ringworm)

  9. Staph hypersensitivity (allergy to their own bacteria)

  10. Neoplasia (cancer)

This is a dog with Cushings

Same dog 2 months later, the hair is growing back!

The workup for a pyoderma is quite variable and depends on the severity and duration of the problem, previous response to treatment, and initial clinical impression. The workup may include:

  1. Test: Skin smear
    Indications: Type of bacteria,allergy,immune-mediated

  2. Test: Skin scrapings
    Indications: Parasites

  3. Test: Fungal culture
    Indications: Ringworm

  4. Test: Skin biopsies
    Indications: Hormonal, immune mediated, allergy, fungal, bacterial, parasitic

  5. Test: Urinalysis
    Indications: Internal diseases

  6. Test: CBC, blood panel
    Indications: Internal diseases

  7. Test: Thyroid abnormalities
    Indications: Thyroid gland abnormality

  8. Test: Cortisol abnormalities
    Indications: Adrenal abnormality

  9. Test: Culture
    Indications: Type of bacteria and antibiotic to use

  10. Test: Histamine test
    Indications: Drug interference

  11. Test: Skin testing
    Indications: Atopy (pollen allergy)

Treatment for pyodermas also can be quite variable. Correction or control of the underlying cause is one of our goals. All pyodermas will need to be on antibiotics for a MINIMUM of 21 days. Topical therapy is often indicated in the form of special shampoos.The prognosis for most superficial pyodermas is good. The deep pyodermas are much more difficult to cure/control. The information gained from the laboratory tests will give us a more precise diagnosis and prognosis. Occasionally, after all of the causes have been eliminated, the pyoderma returns. In these cases, immune stimulating drugs will be tried.

OTITIS EXTERNA (disease of the external ear)

Otitis externa or inflammation of the external ear is a very common ailment in dogs. Often there is an infection present. Symptoms may include: an odor or discharge from the ear, scratching or shaking his head or ear, soreness, or swelling of the ear flap. However, some dogs show very few symptoms and it will only be diagnosed by an otoscopic examination.

Otitis has many INITIATING causes such as flea allergies, atopic dermatitis (an allergic reaction that occurs when an animal inhales airborne substances (pollen, housedust) or ingests (eats) a substance to which they are sensitive), ear mites, or anatomical abnormalities (eg-scar tissue from previous ear infections or polyps/tumors in the ears)

Yeast or bacteria (cocci or rods) infection will complicate otitis externa, however, these germs don't start an ear problem.

In order to diagnose and treat an ear problem, we do the following:

  1. A complete history is taken to help identify an initiating cause.

  2. A complete dermatological exam is done, since frequently the ear is part of an overall skin problem.

  3. A thorough otoscopic exam is done. It is important that the ear canal is evaluated for swelling, discharge or ulcers. The ear drum also needs to be visualized to determine if a middle ear infection exists.

  4. A cytological exam (cell examination) is done to identify what kind, if any, of organisms (yeast or bacteria) are present. This is very important because certain bacteria (rods) are hard to treat and need long term therapy. Also, ear mites can be identified from this test.

  5. An ear flush may be done to completely clear the ear canal and make certain the eardrum is intact. This may be done with light sedation to your pet.

We have the most advanced equipment for diagnosing and treating ear disease, including a video-otoscope. We use this "high tech" equipment to visualize the entire ear canal, ear drum, and occasionally the middle ear on a TV monitor. Through this video-otoscope, we collect samples from the ear canal and apply medications. We can also take pictures of the ear canal and ear drum which assists in monitoring response to therapy.

After the cause of the otitis has been determined, appropriate medication is prescribed. It is essential to do a follow-up exam in 7 days. Although the symptoms may disappear during the treatment, the problem (disease) may persist. Most infections need medication for 7-14 days once the infection is resolved. An otoscopic examination is the only way to be sure the ear problem is gone. If the otitis recurs or becomes chronic, further testing or procedures may be needed (allergy testing, elimination diets, etc).

Even though there are many causes of otitis, most cases respond quickly to treatment especially if the initiating cause is addressed. The sooner the pet with otitis is seen, the easier (and less costly) the treatment may be.

Dr Bloom using video otoscopy to visualize and flush deep inside the ear canal

A vet tech helps with the flushing, this dog is under anesthesia.

This eardrum has a hole, flushing away the infection and infusing medication is the only way to treat it.

The same ear is looking better after a few months.

This is a polyp in an ear canal.

This ear has a lot of debris to flush out before we can see the ear drum.