Guide To Canine Skin Diseases and Conditions

Start Here: How to Diagnose Dog Skin Problems

A veterinarian will attempt to narrow the list of possible causes by taking a thorough history along with a physical exam and some diagnostic lab tests. Dog flea allergy is the leading cause of skin problems, followed by other types of allergies such as environmental dog allergies (atopy) and dog food allergy.

Mange, a parasitic condition that causes patches of baldness, is the next leading cause and is primarily evident in puppies.

Other symptoms which accompany dog skin problems such as severe hair loss and excessive panting could indicate an underlying disorder such as an endocrine disease such as hyperadrenocorticism or Cushing's Disease. Treatment for dog skin conditions involve keeping the skin clean and treating the underlying as well as secondary cause such as bacterial infection or parasites.

Primary vs. Secondary Canine Skin Problems

Your vet will try and determine if  a dog skin problem is primary or secondary. Primary skin lesions are caused by a specific disease. Secondary dog skin issues occur when a disease progresses or from a self-injury such as itching or scratching as is common with dog skin allergy. Secondary dog skin problems can also be a result of bacterial infections.

Identifying canine skin diseases and conditions can be difficult since there are many causes. The key to understanding which condition your dog is suffering from is to do your best to match the characteristics of each cause with the symptoms exhibited by your dog.

Symptoms and Causes of Dog Skin Diseases

Canine skin conditions vary based on shape of the lesions and condition of the skin such as crusts, scars, ulcers, or scales, and the dogs behavior such as itching.  It also depends on the location of these lesions or symptoms on body. The following table describes common symptoms and causes.

Common Causes of Canine Skin Disease

Flea allergy dermatitis, environmental and food allergies are the leading causes of to dog skin lesions and rashes. Even if you don't find any fleas on your dog, they are skilled at hiding, with even a few able to cause a problem in allergic dogs. Symptoms are usually in the form of raised red bumps known as hives. They are itchy and will cause your dog to scratch. Excessive scratching may break the skin, leading to infection.

If no infection occurs, hives will usually go away on their own once exposure to the allergen is removed. If infection develops, however, medical treatment will be needed. See your vet if your dog has sores that don’t go away in a few days, or sores that ooze anything yellowish in color. He may need antibiotics.

Allergies

Allergy is a common cause of canine skin disease. The skin is the largest organ in the dog's body and is exposed to environmental influences such as allergens. Types of dog skin allergy include:

• Atopic Dermatitis (allergen that is inhaled causing a hypersensitivity reaction, most common cause).
• Food Allergy
• Flea Allergy
• Skin Allergy

Atopic Dermatitis

Atopic dermatitis is a reaction to airborne allergens such as powder mites, weeks and tree pollen. It is not clear why the reaction occurs, although it is believed that there is some genetic predisposition among certain breeds⁽²⁾:

• American Staffordshire Terrier
• Boston Terrier
• Boxer
• Bull Terrier
  
• Cairn Terrier
• Dalmatian
• English Bulldog
• German Shepherd
• Fox Terrier
  
• French Bulldog
• Golden Retriever
• Shar Pei
• Shih Tzu
• West Highland White Terrier

Triggers include air pollution, excess hygiene or stress. Allergens enter the body by swallowing, skin contact and by breathing them in.

Symptoms of atopic dermatitis are skin redness (erythema) and itch (puritus) and are usually on the abdomen, feet and face. Scratching can cause additional dog skin problems such as infection.

Treatment of atopic dermatitis skin problems on dogs starts with bathing since it helps to remove any surface allergens. The selection of shampoo should be based on what you are trying to achieve:

• Bacterial or Fungal Infection: Medicated shampoo can address infection or fungal overgrowth.
• Anti-itch: For itchy dogs, consider an anti-itch formulation that contains calming elements such as oatmeal or essential fatty acids such as All Natural Anti-Itch Shampoo.
• Anti-seborrheic shampoo: For dogs that have scaling or seborrhea (dandruff) in addition to the dermatitis. Look for a shampoo such as Duoxo with ingredients such as zinc salts, selenium disulphide, salicylic acid, sulfur or coal tar.

The veterinarian might also recommend a hypoallergenic diet that is formulated for skin and coat health. New products have been introduced that help to improve the skin layer. This includes:

• Phytosphingosin: Helps to improve the lipid composition of the skin. Found in Duoxo spray.
• Topical Essential Fatty Acids: An essential fatty acid spray can help to improve skin barrier function, reduce water loss and improve the hydro-lipidic composition of the skin.

Food Allergy Dermatitis

Food allergy in dogs causes itching on the ears and skin a few minutes, hours or even weeks (usually 24 to 72 hours)⁽³⁾ after consuming an allergen. Food allergy may also make a dog susceptible to bacterial skin infection. The condition can be accompanied by nausea, increased number of bowel movements, diarrhea or vomiting.

Ingredients that commonly cause food allergy in dogs includes:

• beef
• chicken
• corn
• soy
• wheat
• dairy

The condition is diagnosed by providing a hypoallergenic diet or elimination diet (diet of just the basics) and then seeing improvement.

Avoid treats when on this diet as they are often the cause or a cause of the dog skin problem.

Flea Allergy Dermatitis (FAD)

Flea allergy is a condition that pet parents tend to deny, even when the veterinarian makes that the diagnosis. Reasons for dogs getting fleas include:

• Dogs that come in contact with untreated animals.
• Lack of consistent treatment.
• Substitution of less effective and cheaper store bought spot-ons instead of prescription grade products.⁽¹⁰⁾

Symptoms of flea allergy dermatitis include:

• Itch and scratching on the back half of the dog.
• Crusted skin bumps (papules) in the umbilical fold
• Skin lesions (crusted papule) that have a long duration
• Symptoms in the classic areas of the body; dog has scabs on back near tail base, lower back, rear part of the dog and inner thighs.
• Itchy skin nodules

Treatment for flea hypersensitivity involves the use of prescription products that disrupt the flea lifecycle and that kill adult fleas. Goals are to kill any existing fleas and the continued prevention of fleas through the use of spot-ons, collars and oral products.  New spot-on prescription products are applied to the skin every 3 to 4 weeks and are highly effective. We do not believe that over-the-counter products from pet stores provide the same level of residual activity or safety.

Dog Mange

There are two types of dog skin conditions referred to as mange, demodectic and sarcoptic. It is caused by mites, which are generally microscopic and burrows in skin.

Demodectic Mange

Demodectic dog mange is usually mold and heals on its own in 6 to 8 weeks. It could last months in localized areas on the body.(6) Studies show little difference between treated and untreated dogs for small infections that are in one area of the body. For small localized cases, therapies include using benzoyl peroxide or mupirocin massaged into the skin.  

Localized cases (limited areas on the body) could cause small red hairless spots. Other symptoms can include pimples, thick skin and pus, scaling around the eyes, mouth and front legs.

For generalized cases that are all over the body the medication Amitraz, which is a monoaminooxidase inhibitor, is prescribed.  It is a topical that is applied every 2 weeks.

90% of cases can be cured, but can take up to 12 months. To ensure progress is being made a veterinarian may request repeat office visits very month. Many dogs with demodectic mange also get a bacterial skin infection. For this reason an antibacterial shampoo can help to address any skin crusts.

Sarcoptic Mange

Sarcoptic dog mange (scabies)  in dogs is caused by mites. Symptoms include extreme itch, papules, scales and crusts. 

The condition is diagnosed by a skin scraping, although this form of diagnosis is only positive in 30% to 50% of dogs with the condition.⁽⁷⁾

Treatment is with parasiticidal drugs that are administered every 2 to 3 weeks such as as a Selamectin spot-on. Other medications are ivervectin or milbemycin ,but these cannot be used in Old English Sheep dogs or Collies.

Bacterial Skin Infections

Dog bacterial skin infections are commonly referred to as:

• furuncolosis (penetrating or perforating follicular inflammation)
• folliculitis (superficial pyoderma)
•  pyoderma (bacterial infection)

The infections are usually caused by the cover colonization of the skin by Staphyloccoccus. The bacteria is found on normal dog skin, but causes a problem when it grows beyond normal levels, frequently when another condition is suppressing the immune system.

 This can be triggered by:

• Allergies
• Parasites
• Hormonal imbalance
• Kertatnization disorder
• Immunodeficiencies
• Metabolic disorders

Symptoms of a bacterial infection include:

• Rash
• Skin bumps
• Pustules (whiteheads)
• Comedones (blackheads)

Bacterial skin infections can look like Demodectic mange and Malassezia. For this reason, conditions like these need to be ruled out of a Veterinarian before reaching a definitive diagnosis.

Certain breeds such as Standard Poodles, Vizslas, Akitas and Samoyeds suffer from deep pyoderma or infection as a result of the condition sebaceous adenitis. Deep infections can also be helped by antibacterial benzoyl peroxide shampoo. The shampoo works by decreasing bacteria on the skin surface and by reducing the likelihood that an infection will return. Shampoos are used 2x per week.

All dogs suffering from skin infection will need to be re-evaluated for progress.

Folliculitis

Folliculitis is a bacterial skin infection and inflammation that causes mild to more severe skin itch. In most cases allergy is the underlying cause. Antibiotic therapy is frequently used to resolve the problem for a period of three weeks using a combination of oral and topical medications.  If the condition is mild, a antibacterial shampoo or spray could be of help.

Pyoderma

Deep pyoderma refers to cases where there is a more severe skin infection. Most cases involve hair follicles that are infected with Staphylococcal infection. Symptoms include inflammation and redness. The condition is treated for 4 to 8 weeks with antibiotics.  A form of deep pyoderma that affects the skin between dog toes is called Pododermatitis. Oral antibiotics are used to treat Pododermatitis.

Calluses

Calluses (thickened skin) form when a dog consistently lies on hard surfaces. The friction between the hard surface and the skin causes thickening to occur. The most common location is a dog elbow callus, but it could also form in other areas of the body.

Treatment involves replacement of the hard surface with a softer dog bed or blanket. You can use a soothing balm or butter, but do not do this unless you also solve the problem, which is replacing the hard surface with a softer one.

Fungal Skin Infections

Dog fungal infections are also called ringworm or Dermatophytosis. Typical symptoms are hair loss, crusting and scaling in a classic circular pattern. It is less common to see symptoms such as pain, itch or skin inflammation.⁽⁸⁾

It is common to see a dog fungal skin infection on the forelegs (can cause spots on the feet) and face since these come into contact with the environment.

The fungus can invade hair follicles, causing hair loss or feed on the keratin in the skin itself. Dogs with a compromised immune system are at greater risk of fungal infection.

The dog skin problem is diagnosed by examining the skin under a Wood's lamp or a fungal skin culture. Treatment involves the use of topicals (azoles) that contain Ketoconazole, Itraconazole, Fluconazole or other approved medications. A veterinarian might also recommend a medicated shampoo or the use of a Lime-suflur dip used 2x per week.

All items in a household with a fungal infection patient should be cleaned thoroughly.

Dog Skin Ulcers

A dog skin ulcer is a type of wound where there is a breach in skin continuity and it doesn't heal at it's own. Since dogs have relatively thin skin, diseases that damage the skin or self-trauma results in an ulcer.⁽¹⁵⁾

There are several potential causes of skin ulcers in dogs. These skin problems in dogs include:

• Histoplasmosis: fungal infections characterized by ulceration and skin lesions.
• Leishmaniasis: nose ulcers 
• Lymphoma: cancerous bumps
• Melanoma: dark lesions on older dogs
• Panniculitis: caused by skin injury or an autoimmune disorder
• Phaeohyphomycosis: contaminated wound
• Pyoderma: bacterial skin infection
• Pythosis: skin sores on legs
• Sebaceous Gland Tumors: tumors that form on the skin
• Spider bites: skin swelling after bite

Diagnosis of Canine Skin (Integumentary) Problems

Your vet will examine your dog's skin carefully as part of a complete examination. The exam will start with a thorough history since many dog skin disorders are more common in certain breeds and at specific ages. There is also a higher incidence of specific types of dog skin problems in some breeds.

In order to properly diagnose diseases and conditions canine skin, various tests may be needed along with physical examination. Tests might include:

• Examining skin under a special light (a woods light): this is done to check for certain fungal infections such as ringworm.
• Dog skin biopsy: in this test, a needle is used to remove cells from a lump to be examined by a pathologist. This can determine if a lump is cancerous or if it is just a cyst or wart.
• Blood tests: might be done to check for infections and certain nutrient deficiencies.

If you keep your dog clean and it continues to smell or have a greasy coat then your pet is probably suffering from parasites, seborrhea or a skin infection.

Dog Skin Problems by Age

Dog Skin Conditions by Body Location

Skin Issues in Dogs by Breed

Dog breed can also provide some clues when it comes to skin conditions, particularly in purebred dogs. Since these dogs are bred for certain traits, they also tend to pass on the same undesirable traits, including skin disease. Disease is also passed on genetically through line or in-breeding when a small stud population is used for breeding. Dog skin problems can be limited to one litter, one breed, or could be seen across certain breeds. Some of the more common breed specific canine skin diseases and conditions are described below:

Treatment

The treatment of canine skin diseases and conditions depends on the exact disease or condition. Treatment may involve oral or topical medication. It may also involve removal of any lumps or bumps from your dog's skin. If your pet's skin is affected by poor nutrition, treatment will involve making a correction in the diet.

There is a myth that baths are not good for dog skin diseases and conditions. This is not correct as bathing is an important part of just about every skin treatment. Shampoos are particularly effective on bacterial and fungal infections with a medicated bath 1 - 2 times per week.  They also help to remove any allergens that are caught in the dog's coat.

If a bacterial has progressed deep into the skin then antibiotics are needed. You should also carefully look at your dogs diet and if it is causing any of the canine skin problems. Follow this link to understand Dog Food for skin or sensitive skin dog food.

For dry skin, If all other causes are ruled out, then you might want to consider using oil for dry dog skin.

You can also fill out the form below where you can ask a free canine skin question. Our veterinarian answers several questions a week.

Treating Mild Allergic Skin Reactions

Approximately 1.2% of visits to a veterinary emergency room are for what are called mild allergic reactions. Vets refer to these as Type 1 hypersensitivity reactions. These skin reactions are triggered when skin cells called basophils and mast cells and the immunoglobulin E antibodies on the surface of those cells come in contact with an allergen. The contact can occur via injection, inhalation, ingestion or direct contact.

When the cells come in contact with the allergen they release prostaglandins, leukotrienes and histamine. In turn you start to see an allergic reaction including:

• Urticaria (skin rash)
• Pruritus (itchy skin)
• Angioedema (skin swelling, hives)
• Anaphylaxis ( a chronic life threatening allergic reaction that could result in issues with heart function and heart collapse)

Treatment usually takes one of two forms:

1. Use of the medication Diphenhydramine (2 mg/kg IM once)
2. Oral diphnhydramine (2 mg/kg PO every 8 hours for 2 to 3 days)

While Doctors used to prescribe a corticosteroid during the first treatment, research now shows that this is not necessary and does not improve the outcome.⁽¹⁶⁾

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Brochures on Skin Disorders in Dogs

References for Skin Disease in Dogs

(1) Swaim SF, Henderson RA (1990) Small Animal Wound Management Lea and Febiger, Philadelpha, pp 52-86

(2) Skin and coat care of the atopic dog. Laura Navarro Combalia. Departamento de Patologia Animal. Facultad de Veterinaria. Universidad de Zaragoza. Clinica Veterinaria August. Zaragoza. October 2012.

(3) Food Allergy Dermatitis; S. Colombini Osborn; Southwest Veterinary Dermatology, 2006

(3) Washington State University

(4) Carmichael, L. Recent Advances In Canine Infectious Diseases

(5) Management Challenges in Canine Pyoderma
Peter J. Ihrke, VMD, Diplomate ACVD

(6) Treatment of Canine Generalized Demodicosis; R.S. Mueller, Faculty of Veterinary Medicine, Ludwig-Maximillians-University, Munich, Germany

(5) School of Veterinary Medicine, University of California,
David Scott, D. W., Miller, W. H., Griffin, C. E.Muller and Kirk’s Small Animal Dermatology

(6) Canine and Feline Demodicosis
Didler-Noel Carlotti Dr. vet DIP ECVD
Eysines (Bordeaux), France EU

(7) Sarcoptes, Demodex and Otodectes: Treatment Options, R.S. Mueller, Faculty of Veterinary Medicine, Lugwig-Maximillans-University, Munich, German

(8) Dermatophytosis: Still Underdiagnosed & Overdiagnosed. Dr. Peter J. Ihrke

(9) Viral Diseases of the Dog, Remo Lobetti, PHD, Internal medicine Braystron Veterinary Hospital

(10) A Standard of Care, Flea Allergy Dermatitis. Peter F. Ihrke, VMD, Diplomate ACVD, Professor of Dermatology, School fo Veterinary Medicine, University of California.

(11) Merck Veterinary Manual, Flea Allergy Dermatitis

(12) Canine Osteosarcomas
Alfred M. Legendre, DVM, MS DACVIM
College of Veterinary Medicine
University of Tennesse, Knoxville, TN

(13) Wandering Through the Autoimmune Dermatosis: Pemphigus Complex
Carlos Eduardo Larsson

(14) Sun-Induced Skin Lesions in Dogs
Alexander Werner, VMD, DACVD
Animal Dermatology Center

(15) Understanding the Language of the Skin, Peter Hill, BVSc, The Royal (Dick) School of Veterinary Studies

(16)  Vet Emerg Crit Care (San Antonio). 2021;31(3):380-386