Pet Dermatology & Allergy Care in San Jose, CA

When a pet is constantly scratching, licking, or chewing at their skin, the discomfort is obvious. But the reason behind the itch can vary widely. Allergies — whether to environmental triggers like pollen and dust mites or to ingredients in food — are among the most frequent culprits. Parasites such as fleas and mange mites also cause intense itching, and bacterial or yeast infections can develop secondary to the initial irritation.

Chronic itching that persists for more than a few weeks, or itching that recurs seasonally or despite basic treatments, deserves a systematic veterinary evaluation. Our veterinarians will examine your pet's skin and coat, look for parasites, evaluate the ears, and may recommend skin scrapings or cytology to identify what's happening at the skin surface. From there, we can build a targeted treatment plan rather than relying on temporary relief alone.

In some cases, what looks like simple itching may be linked to an underlying medical condition such as thyroid disease or adrenal imbalance, which is why a thorough evaluation matters.

Allergic dermatitis is one of the most common skin conditions in dogs and cats. Environmental allergies (atopy) are triggered by substances like pollen, mold spores, dust mites, and grasses that are inhaled or contact the skin. Food allergies involve an immune response to specific proteins in the diet — chicken, beef, dairy, and egg are among the most common offenders. Flea allergy dermatitis is an extreme sensitivity to flea saliva, where even a single bite can trigger a widespread reaction.

Allergies typically present as chronic itching, recurring ear infections, paw licking, or skin rashes that worsen at certain times of year. Diagnosing allergies is a process of elimination. For food allergies, this often involves a structured elimination diet lasting eight to twelve weeks. For environmental allergies, intradermal skin testing or serum allergy testing can help identify specific triggers.

Once identified, treatment may include allergy-specific immunotherapy, medications to control itch, medicated baths, and strategies to reduce environmental exposure. Managing allergies is rarely about a single fix — it's about building a long-term plan that keeps your pet comfortable throughout the year.

Ear infections cause noticeable discomfort: head shaking, scratching at the ears, a foul odor, redness, swelling, and discharge that may be brown, yellow, or dark in color. Dogs with floppy ears, heavy coats, or a history of allergies are particularly prone. Cats develop ear infections too, though less frequently than dogs.

The most common organisms involved are yeast (Malassezia) and bacteria, but the underlying reason the infection developed matters just as much as treating the infection itself. Allergies are a leading predisposing factor — they alter the environment inside the ear canal, making it more hospitable to overgrowth. Moisture from swimming or bathing, foreign bodies, and ear anatomy can also play a role.

Treatment typically involves ear cleaning, topical medications, and sometimes oral antibiotics or antifungals depending on severity. Because untreated or recurrent ear infections can lead to chronic changes in the ear canal, early evaluation is important. If your pet has had multiple ear infections, investigating the underlying cause — particularly allergies — can help break the cycle.

Pyoderma — a bacterial skin infection — can appear as pustules, crusted bumps, circular lesions with hair loss, or inflamed, oozing patches. It may be superficial, affecting only the upper layers of skin, or deep, involving the hair follicles and deeper tissues. Deep pyoderma is more serious and may require longer courses of treatment.

Yeast dermatitis, caused by Malassezia overgrowth, often produces greasy skin, a musty odor, thickened or darkened skin, and chronic itching. It commonly affects skin folds, ears, paws, and areas where moisture tends to accumulate. Both bacterial and yeast infections frequently occur secondary to another condition — allergies, hormonal imbalances, or immune suppression — so treating the infection without addressing the root cause often leads to recurrence.

Diagnosis involves skin cytology — examining a sample of the affected skin under the microscope to identify which organism is present. This guides the choice of topical or systemic therapy. Medicated shampoos, topical treatments, and oral medications are all tools we use depending on the severity and depth of the infection.

Flea allergy dermatitis is the most common skin disease in dogs and cats worldwide. Even a small number of fleas can trigger an intense allergic reaction in sensitive animals, leading to scratching, hair loss, and secondary skin infections — often concentrated along the lower back, base of the tail, and inner thighs. Importantly, you may never actually see fleas on an allergic pet because they groom them off quickly.

Mange is caused by microscopic mites that live in or on the skin. Demodex mites are normally present in small numbers but can overpopulate in immunocompromised or young animals, causing patches of hair loss and scaling. Sarcoptic mange (scabies) causes intense, generalized itching and is contagious between animals. Ear mites are another common parasite, particularly in cats, and cause head shaking, dark crumbly discharge, and ear irritation.

Diagnosis typically involves skin scrapings examined under a microscope to identify mites. Treatment depends on the parasite and may include topical or oral parasiticides, ear treatments, and environmental flea control. Year-round parasite prevention is one of the most effective ways to protect your pet from these conditions.

Hair loss in pets can be distressing to observe, and the causes are varied. In many cases, hair loss is secondary to scratching or chewing driven by itch — allergies and parasites are frequent contributors. In other cases, the hair falls out without significant itching, which may point toward endocrine (hormonal) conditions such as hypothyroidism in dogs or hyperadrenocorticism.

The pattern and distribution of hair loss often provides diagnostic clues. Symmetrical hair loss along the trunk may suggest a hormonal cause, while patchy, irregular hair loss with redness and crusting is more consistent with infection or mange. Hair loss confined to specific areas may indicate friction, pressure sores, or localized skin disease.

Our diagnostic approach may include skin scrapings to look for parasites, cytology to check for infection, blood work to evaluate thyroid and adrenal function, and in some cases biopsy. Identifying whether the hair loss is driven by inflammation, infection, hormones, or an immune-mediated process determines the right treatment path.

A hot spot develops when a patch of skin becomes irritated and inflamed, and the pet's continued licking or chewing accelerates the damage. The result is a raw, moist, often weeping lesion that can expand quickly — sometimes growing significantly in just a few hours. Thick-coated breeds and dogs with heavy undercoats are especially susceptible, as moisture and heat trapped against the skin create an ideal environment for bacterial overgrowth.

Common triggers include flea bites, allergic flare-ups, matted fur, moisture from swimming or bathing, and underlying skin irritation. Once the cycle of itch and self-trauma begins, the area becomes increasingly inflamed and infected, making it unlikely to resolve without veterinary intervention.

Treatment involves clipping the hair away from the affected area, thoroughly cleaning and drying the wound, and applying topical or systemic antibiotics along with anti-inflammatory therapy. An Elizabethan collar may be needed to prevent further licking. Addressing the underlying trigger — whether fleas, allergies, or another skin condition — is essential to prevent recurrence.

When skin problems keep coming back despite treatment, there is usually an underlying reason that needs to be identified and managed. Chronic allergies are a leading cause — allergic pets may experience flare-ups seasonally or intermittently throughout their lives. Hormonal conditions, immune-mediated diseases, and structural abnormalities in the ear canal can also contribute to recurring issues.

Recurrent skin disease can be frustrating for both pets and owners. The key is shifting from reactive treatment of individual flare-ups to proactive management of the underlying condition. This may include consistent flea prevention, allergy-specific immunotherapy, medicated bathing routines, dietary adjustments, and regular monitoring to catch problems early before they escalate.

Our veterinarians work with owners of pets with chronic skin disease to develop manageable, sustainable plans that reduce the frequency and severity of flare-ups. If your pet has been through multiple rounds of antibiotics or steroids without lasting improvement, it may be time to investigate the root cause more thoroughly.

Accurate diagnosis is the cornerstone of effective dermatology care. A thorough physical exam is the first step, where our veterinarians evaluate the distribution of lesions, the type of skin changes present, and whether the condition is primarily itchy or non-itchy. From there, diagnostic tests help narrow down the cause.

Skin scrapings involve gently scraping the skin surface to collect cells and organisms for microscopic examination — this is how mange mites are identified. Cytology uses tape preparations or impression smears stained and viewed under the microscope to detect bacteria, yeast, and inflammatory cells. Bacterial cultures may be pursued when infections don't respond to standard treatment or when resistant organisms are suspected.

Allergy testing — either intradermal skin testing or serum testing — helps identify specific environmental triggers for pets with suspected atopy. Blood work, including thyroid levels and other hormone panels, can rule out endocrine causes of hair loss and skin changes. In select cases, skin biopsy provides additional diagnostic information when autoimmune or neoplastic conditions are suspected.