Connecticut's only clinic dedicated to veterinary dermatology and the allergies of dogs and cats

Allergic skin disease is the most common condition that we treat in both dogs and cats.

Allergic skin disease is a clinical diagnosis based on a combination of the patients’ history, clinical exam findings, and ruling out other potential causes of the clinical signs. The most common clinical signs in dogs are itchiness and recurrent skin or ear infections, while cats have 4 major allergy manifestations—eosinophilic granuloma complex, self-induced alopecia, head and neck pruritus (itchiness), and miliary dermatitis.

The three major causes of allergies in both cats and dogs are insect bite hypersensitivity, environmental allergies, and food allergies. Many patients have some component of allergies to all three categories.

An allergy work-up generally consists of:

1. Eliminating ectoparasites (fleas, mites) and thereby getting rid of any insect bite hypersensitivity.
2. Performing a strict elimination diet trial using a prescription hypoallergenic diet to evaluate for food allergies. Allergy testing for food allergens, regardless of current methodology, is only able to identify what allergens the patient has been exposed to and is not accurate to identify allergens.
3. Considering allergy testing for environmental allergies once we have confirmed a diagnosis of atopic dermatitis (environmental allergies) based on response to #1 and #2 or if there is a strong seasonal nature to the clinical signs.

Allergy management is generally life-long and multi-factorial. It will often consist of medications to manage symptoms, topical therapy to help restore the skin barrier and prevent infection, and allergen specific interventions, such as allergen avoidance and allergen specific immunotherapy (ASIT). ASIT involves giving the patient small, regular doses of their allergens to build tolerance to the allergens.

Endocrine disorders are diseases that result from imbalances of systemic hormones. The most common conditions we treat are hypothyroidism, where the body makes too little thyroid hormone, and Cushing’s disease, where the body makes too much stress hormone (cortisol). Other, less common endocrine disorders are atypical Cushing’s, where the adrenal glands make excess non-cortisol hormones, and sex-hormone related conditions.

Endocrine disorders commonly cause skin and ear infections, because they affect the skin’s immune system. They also often cause non-inflammatory hairloss, where the skin in the areas of hairloss isn’t itchy or inflamed. Because these hormones affect the entire patient, they often come with clinical signs affecting other organ systems, such as weight gain, change in appetite or thirst, and changes to urination, or infections elsewhere in the body, such as urinary tract infections.

Endocrine disorders are diagnosed via a combination of different blood tests and skin biopsies. Treatment involves normalizing the imbalanced hormones.

Hair loss must be broken down into 2 categories, inflammatory alopecia (the skin is red and inflamed and likely itchy) and non-inflammatory alopecia (the skin is not red or itchy).

Inflammatory alopecia is most generally caused by an infection, allergies, or ectoparasites, whereas non-inflammatory alopecia is often caused by endocrine disorders, hair cycle arrest (where the hair follicles stop cycling), follicular dysplasias (malformed hair follicles), amongst others.

Inflammatory alopecia can generally be evaluated by in-house diagnostics, such as skin surface cytology to check for infection and skin scrapings to check for parasites.

Non-inflammatory alopecia usually requires a combination of blood testing to evaluate for endocrine disorders and skin biopsies to evaluate the hair follicles inside the skin itself.

Treatment depends upon the underlying cause of the alopecia. For example, for cyclic flank alopecia, a form of hair follicle arrest that may be related to day length, a melatonin implant may be helpful. For Alopecia X, dermal microabrasion using a Dermaroller can be effective. For Alopecia Areata, an immune-mediated condition where the immune system attacks the hair follicles, treatment involves immunomodulatory medication (medications that suppress or reduce the immune system).

Skin parasites are very common in the Northeastern US. In addition to the usual fleas and ticks, Sarcoptic mange, caused by microscopic scabies mites, is endemic in the fox population of Connecticut and New York. Patients with sarcoptic mange are insanely itchy. Many have crusting on the margins of the ear flaps and outsides of their limbs.

Itchy creepy crawlies are evaluated for via combing, plucking, and scraping the affected areas. These critters are generally detected in the exam room, though there is a blood test that evaluates for antibodies to sarcoptic mange that can be helpful.

Treatment involves the appropriate ectoparasiticide, as well as appropriate environmental decontamination and treating in-contact pets. It must be noted that some of these conditions can be zoonotic (potentially transmitted to in-contact humans).

The most common forms of skin tumors seen in dogs and cats are benign. Many are benign tumors of the glands of the skin (sebaceous adenoma-complex masses) or hair follicles (follicular cysts or follicular tumors). Other generally benign skin tumors include plasmacytomas, melanocytomas, and histiocytomas. However, there are skin tumors that are cancerous/can metastasize or spread, such as mast cell tumors, melanoma, squamous cell carcinoma, and Bowen’s disease. Then, there is a form of widespread skin cancer called cutaneous epitheliotropic lymphoma, which is a very aggressive form of skin cancer that can appear all over the entire body. Tumors inside ear canals may initially present as recurrent ear infections that only affect one ear, especially in older dogs and cats.

There are 2 main types of diagnostics used to evaluate skin tumors:

1. Fine needle aspiration and cytology: This is where we take a sample of the lesion using a needle. We suck back/aspirate cells, spread them on a slide, and send them to a pathologist, who attempts to identify what the tumor is based on what cells are present. This is a very minimally invasive, well-tolerated procedure, but sometimes the pathologist cannot give us an answer—either because the tumor-type doesn’t shed cells easily/holds on tightly to its cells, or because the pathologist needs to see the cells in an organized structure to make the diagnosis.
2. Biopsy allows the pathologist to see the cells in that organized structure. Biopsy involves either removing the nodule/lesion or a piece of the lesion and evaluating slices of the tumor under the microscope. Special stains or immunohistiochemistry may be needed to further identify exactly what type of tumor it is. Biopsy requires local anesthesia (lidocaine); depending on the location and the dog or cat’s disposition, it may require sedation or even general anesthesia. However, despite these inconveniences, biopsy almost always gives us an answer as to the identity of the tumor and therefore the patient’s prognosis and treatment options.

These are skin diseases caused by the immune system, either via the immune system attacking the skin itself, the immune system indirectly damaging the skin, or inappropriate inflammation of the skin with no identifiable target. Almost always, these types of diseases must be diagnosed via skin biopsies.

The most common immune-mediated diseases we treat include:

1. Pemphigus foliaceus, a condition where there is an auto-immune attack on the connections between the skin cells, causing the skin cells to detach from each other. This leads to the formation of fragile pustules, which rapidly coalesce into crusts. This condition classically affects the nasal planum (black part of the nose), extending onto the haired muzzle (bridge of the nose), around the eyes, undersides of the ear flaps, and the foot pads. In cats, favorite areas for this disease to attack, in addition to the face, are the toenails and around the nipples. Many patients have generalized versions of pemphigus, where their entire bodies are affected. The patients can act sick or be insanely itchy. These patients need powerful immunosuppressive treatment, often life-long. This is generally our most common severe auto-immune skin disease that we treat.
2. Discoid lupus erythematosus. In its most common version, this condition causes loss of cobblestone architecture, depigmentation, and crusting of the nasal planum, and almost exclusively involves dogs. The skin around the eyes and lips can also be affected. Rarer versions involve the entire body, but it is limited to the skin and does not involve the internal organs. It is exacerbated by UV light exposure. It is treated by topical or oral immunomodulatory medication and UV avoidance.
3. Sebaceous adenitis. This is a disease where the immune system destroys the sebaceous glands of the skin. These glands are important for maintaining healthy hair follicles and preventing skin infections, so these patients are often bald, scaly, and have secondary infections. They may or may not be itchy. This condition can affect any breed, but there are strong genetic predispositions in certain breeds, particularly Poodles and Doodles, Havanese, Vizslas, and Akitas. Treatment is a combination of topical therapy, essential oils, and immunomodulatory treatment.
4. Sterile nodular panniculitis. This is an immune-mediated condition where the fat becomes inflamed. This causes painful subcutaneous nodules that eventually rupture and drain. The condition often comes on acutely, with the patients feeling sick, febrile, and extremely painful. It is treated with immune-suppressive medication. This condition can have known triggers (pancreatitis, subcutaneous injections) or be idiopathic (no known cause).
5. Juvenile cellulitis/puppy strangles. This is a disease mostly seen in puppies or juvenile dogs, where they develop subcutaneous swellings, swollen lymph nodes and eyelids, which then crust and drain. This condition is likely caused by a combination of genetic predisposition and some immunogenic trigger, such as vaccination. It is treated with immunosuppressive therapy. It is generally transient and does not need life-long therapy; the puppies go on to live normal lives.
6. Symmetric lupoid onychodystrophy (SLO). This is an immune-mediated condition limited to the toenails, where all nails of all feet are fragile, brittle, and misshapen. This condition is generally diagnosed based on clinical impression, as biopsy requires amputating a digit. It is treated with immunomodulatory therapy, fish oils, biotin, and therapies to help increase blood flow to the nail beds.
7. Vasculitis means inflammation of the blood vessels. When the blood vessels are inflamed, there is decreased blood flow and decreased oxygen delivery, leading to damage or even death of the dependent tissue. Vasculitis can be limited to the ears (ear margin vasculitis or proliferate thrombovascular necrosis of the pinnae) or affect other areas on the body, such as the tail tip, nail beds, pawpads and areas of wear and tear such as the skin over joints. The affected areas often lose hair and tissue. Vasculitis is often caused by conditions that lead to the buildup of excessive immune complexes in the blood. Immune complexes are formed by an antibody binding to an antigen. Common causes of excessive immune complexes include tick borne disease and vaccinations. Vaccine-associated vasculitis may lead to recommendations to avoid certain vaccinations in the future. Treatment for vasculitis involves increasing blood flow through damaged tissue and decreasing the inflammation of that tissue through immunomodulatory treatment.

8. Perianal fistulas and metatarsal fistulas. Perianal fistulas involve painful draining fistulous tracts around the anus, while metatarsal fistulas are draining tract and ulcerative lesions on the back of the hind legs, immediately above the paw. Both conditions are much, much more common in German Shepherds than other breeds but can be seen in any breed. Treatment involves immunomodulatory therapy, either orally or topically (or both).
9. Cutaneous adverse drug reaction. Skin eruptions/rashes can be seen as immune-mediated adverse reactions to drugs. Drugs commonly implicated include various antibiotics and anti-inflammatory medications, amongst others. Treatment involves drug removal and immunomodulatory treatment to control the immune response.

These skin diseases are caused by or can be treated with nutrition. They are generally diagnosed via skin biopsies.

1. Zinc responsive dermatosis type I: Nordic breeds, such as Siberian huskies, Malamutes, and Samoyeds, amongst others, are predisposed. It is thought that they have a genetic condition that decreases dietary zinc absorption. These patients develop symmetric crusting around the lips, eyes, over the limbs, and on the footpads, though it can be quite generalized. It can also be very itchy. This condition is treated with zinc supplementation. 
2. Zinc responsive dermatosis type II: This condition is seen in rapidly growing juvenile large or giant breed dogs, such as Doberman pinschers, German Shepherds, Labrador retrievers, and Great Danes. These puppies develop crusting on the face and limbs. Correcting the diet to eliminate zinc-binding foods and supplementing with zinc usually resolves this condition.
3. Hepatocutaneous syndrome or superficial necrolytic dermatosis (SND): This condition usually is secondary to severe liver disease, where the skin becomes depleted of essential amino acids secondary to the liver’s inability to process them. This leads to severe crusting of the mucosa and foot pads, as well as other areas on the skin. The liver has a classic honeycomb appearance on ultrasound, and the biopsy findings are distinctive. Treatment involves infusions of the missing amino acids, as well as nutritional support.

Give us a call if you’re unsure whether you need an appointment, and our office will advise you.