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11 Common Dog Skin Lesions and Problems [with Pictures]

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Everything you need to know about skin lesions, skin problems, and skin cancer in dogs.


The skin is the largest organ of the body and it is the surface through which your dog interacts with the outside world. Because of this, your dog may come into contact with all sorts of insulting agents that can cause damage to your dog’s skin. Sometimes, this damage may come from internally in the form of autoimmune or allergic conditions.

While petting or brushing your dog you might come across a skin lesion; skin lesions can take many shapes and sizes, and some are more of a cause for concern than others. It is therefore important for owners to know what different types of skin lesions there are, how harmful they can be to your dog and when you should take your dog to the vet to have them checked out.

11 Common Types of Dog Skin Lesions and Problems

The term skin lesion can refer to any area of skin that has an abnormal appearance when compared to the skin surrounding it. It can be thought of a defect of some kind, whether that be a growth, wound, rash or infection to name a few.

The most common types of skin lesions found in dogs are as follows:

1. Lumps and Growths

Abnormal growths on your dog’s skin are a concern to any owner. Many dog parents will see a lump and immediately think of the word cancer (Read my related article on skin lesions due to cancer). However, many skin lumps are benign and usually nothing to worry about – it is therefore important to know the difference.

In general, lumps that are growing rapidly or changing in shape or appearance can indicate a more sinister underlying cause. Cancerous cells are constantly replicating and mutating and therefore by definition a malignant mass will be changing frequently. Lumps that are hard, red, or ulcerated can indicate a cancerous mass as the surrounding tissues are damaged by inflammation. The most common types of malignant skin cancers found in dogs are mast cell tumors, malignant melanomas, and squamous cell carcinomas. Skin cancer more commonly affects older dogs. You can find more information on skin cancer in dogs here.

However, many skin growths will be benign and generally nothing to worry about. Lumps that are growing slowly, feel soft or fatty or appear just like skin tags are usually not cancerous in origin and are only removed if they’re catching on things or becoming irritated.

You should never assume the severity of a mass based on its appearance alone. Even seemingly innocent lumps can be cancerous and vice versa. The only real way to tell is to have the lump tested by your veterinarian.

View our page featuring Common Dog Lumps, Tumors, Cysts, and Warts (with Pictures).

infographics dog lumps, tumors, cysts and warts

2. Allergic Dermatitis

Dermatitis is inflammation of the skin due to allergies causing areas of skin affected to become red, flaky, thickened, and itchy. Excessive rubbing and irritation can lead to hair loss and the breakdown of the skin barrier allows bacteria to set up secondary infections, resulting in further damage.

Allergic dermatitis can have many causes and is often due to a genetic predisposition that leaves dogs allergic to anything from food, parasites, and environmental pollens. Repeated exposure to the allergen will cause chronic damage to the skin over time and results in a very itchy, irritated, and sad dog.

WATCH: 3 Important Tips To Care For an Old Dog [VET VIDEO]

Dermatitis Photo Gallery:

Dogs with repeated signs of dermatitis should have potential allergens investigated and eliminated.

3. Folliculitis

Resulting in sores, scabs and bumps, folliculitis is a bacterial infection of the hair follicles from which your dog’s fur grows. The follicles become inflamed, and the surrounding skin becomes scaly. Dogs affected with folliculitis will often have lesions in areas where the fur is thinnest, and the overall coat quality may be dull and poor.


4. Hot Spots

Hot spots, as the name suggests, are discrete isolated inflamed and moist lesions. The surrounding areas of fur are typically very wet. There can be various causes of hot spots including bacterial infections, insect bites and allergies.

dog hot spot showing wetness
a hot spot on a dog

5. Ticks

Easily mistaken for skin tags, ticks are parasites that feed on a dog’s blood by burying their head under the skin. They are often painful and can cause inflammation in the surrounding tissues. Tick’s can also transmit diseases such as Lyme disease and a severe tick infestation can even result in anemia from blood loss.

tick next to a dog's eye

6. Mange

Mange is an infestation of the skin by mites that results in extreme itchiness, sore skin, and hair loss. The mites damage the fragile cells on the surface of the skin and in some cases such as demodectic mange, the mites can burrow deep into the hair follicles interfering with hair growth.

dog with red mange

7. Hair loss (alopecia)

While a dog’s coat may naturally thin at certain times of the year, complete areas of baldness are not normal and can indicate an underlying health condition. There are many causes of alopecia including stress, hormonal disease, self-trauma, external parasites, and poor nutrition. If your dog’s hair isn’t growing back, then you should have them seen by your vet.

dog wth hair loss

8. Ringworm

Despite being named after a worm, ringworm is in fact caused by a fungus. It infects the skin in circular lesions resulting in soreness and hair loss. It is an infection that can spread very fast and can even pass to humans. Your vet will be able to perform various tests to determine whether a fungus is the cause of your dog’s lesions and treat accordingly.

9. Flea bites

Below is a picture of dog skin after flea bites. Fleas are hard to spot but their droppings or eggs can be usually spotted in a dog’s coat. Dogs with fleas will typically excessively lick, scratch or even have scabs or hot spots.  

10. Black spots

One condition that I commonly see in my veterinary practice is discolored or black areas on the skin. Most instances of dark or black spots on the skin of dogs are hyperpigmentation. Hyperpigmentation occurs when there is an increase in dark pigmentation of the skin.

The pigment of skin cells is what gives the skin its color. The substance in these cells that make this color is called melanin. Specialized cells in the skin produce melanin. If these cells become damaged, it may affect melanin production.

hyperpigmentation and black spots on a dog's skin

11. Flaky skin

Often, flaky skin is nothing to worry about. Just like humans, dogs can get flaky skin. Giving your dog fatty acid supplements or using moisturizing shampoo may help. However, flaky skin can also be an indication of something more serious going on with your dog, including allergies, mange, autoimmune disorders as well as other skin conditions. If flaky skin persists, makes your dog uncomfortable or if you observe other symptoms, consult your veterinarian.

How to Identify Skin Issues with Dogs

As you can see there are a multitude of skin lesions and skin problems that can affect dogs, some of which are more obvious than others. Some lesions may cause your dog to display symptoms such as itchiness or pain, whereas others may go for months or even years undetected. It is therefore important to have a regular routine for checking your dog’s skin and coat.

The best way to check your dog is to make a habit of it. Pick the same time once a month or even once a week and take the time to thoroughly inspect your dog. Let your dog think it’s a game and be sure to reward them afterwards. Your dog will also see it as a grooming session, helping to make the bond between you and your pooch stronger.

First look at your dogs’ skin and coat from a distance. What is the quality like? Is the coat dull or in poor condition? Are there any obvious areas of redness or inflammation?

Disclaimer: This website's content is not meant to be a substitute for veterinary care. Always consult with your local veterinarian for health decisions. Learn more.

Next run your hands over your dog feeling for any abnormalities or lumps. Pay close attention to your dog’s reaction while you do so, even subtle facial expressions may give away areas of discomfort or pain.

Run a brush through your dogs’ fur and make a note of how much hair pulls out – if large clumps come away and leave areas of baldness then there is likely an issue. Next wipe the brushings on some wet paper towel, if any small specks turn red then they are likely flea dirt (flea poop), indicating that a flea infestation is present.

It can be a good idea to take photos of any lesions and to make a diary of any abnormalities found.

What to Worry About

Any dramatic changes in your dog’s skin or the sudden appearance of sinister looking lesions should be investigated as soon as possible. Similarly, if any lesions are causing your dog a lot of discomfort or resulting in them causing themselves a lot self-trauma then veterinary intervention is likely required.

It’s also important to pay attention to how your dog is as a whole. If they are unwell in themselves or if you’ve noticed any other changes in their behaviors or habit, then you should take them to the vet.  


The treatment of skin lesions will depend very much upon which lesion is present.

Lumps and growths should be tested if they are changing in shape or size. Cancerous lumps should be removed, and, in some cases, chemotherapy may be an option. Benign lumps can be removed if they are causing your dog discomfort.

Allergies require removal of the underlying allergen if possible, such as switching to a hypoallergenic diet in the case of food allergy. Some allergens cannot be avoided however, so anti-itch medication may be prescribed to your dog and any secondary bacterial infections treated with antibiotics.

Bacterial skin infections such as folliculitis and hot spots may be treated with antibiotics, steroids, and topical shampoo treatments.

Parasitic infestations require anti-parasitic medications. Ticks should be removed by your vet as to not leave the tick’s head in your dog’s skin.

Ringworm is treated with a long course of anti-fungal medication which can be given to your dog orally or applied topically depending on the extent of the infection.

Hair loss can be indicative of many causes, many of which are the issues listed above. Once these have been ruled out, other causes such as hormonal diseases such be investigated and treated accordingly.

Many of these conditions can be treated and often don’t require ongoing medication. Once the condition is treated it will have little to no impact on your dog’s life expectancy. However, in the case of allergies or hormonal conditions, long term treatment is often necessary.

Cushing’s disease and hypothyroidism are two endocrine conditions that can result in hair loss. If these condition are treated properly then your dog can go on to lead a normal long life. However, if left untreated, these conditions can severely affect your dog’s quality of life and life expectancy. Similarly, if skin cancer is diagnosed then long-term treatment and prognosis will depend on the type of cancer and how aggressive it is.

4 Recommendations to Reduce the Risks for Skin Lesions and Problems

While some skin conditions can’t be prevented, some can be avoided or minimized with steps that an owner can take at home. Good hygiene is essential, especially when it comes to preventing bacterial or fungal infections. Here are some tips for keeping your dog’s skin and coat in tip top condition:

  • Bathe your dog no more than once a month and use a moisturizing shampoo

While it may seem counterintuitive, washing your dog too often can cause issues. Your dog’s skin is home to many natural ‘good’ bacteria that help fight off the bad stuff, so washing too regularly can remove this healthy flora, leaving your dog’s skin open to infection. If your dog is prone to allergies or skin infections, then consider using a prescription medicated shampoo – your vet can advise you on this.

  • Pay close attention to your dog’s diet

A well balanced and nutrient rich diet will ensure that your dog’s skin is functioning optimally. Fish oil and omega 3 supplements can help keep your dog’s fur shiny and keep the barrier to the outside world well intact. If you suspect your dog is suffering from allergies, then you should try a hypoallergenic diet – the ‘hydrolyzed’ diets are best.

  • Brush your dog’s coat regularly

Brushing is not only great for forming a bond between you and your dog, but it will also help remove any dirt, debris and dead skin cells than may have accumulated in your dog’s thick coat.

  • Keep your dog’s anti-parasite treatments up to date

You should be regularly treating your dog for fleas, ticks and mites, especially if they are the sort of dog that likes to rummage in the undergrowth. Treating every 1-3 months is recommended. Use proper veterinary prescriptions products as many over-the-counter treatments are not strong enough.


  • Alex Crow is an RCVS accredited Veterinary surgeon with special interests in neurology and soft tissue surgery. Dr Crow is currently practicing at Buttercross Veterinary Center. He earned his degree in veterinary medicine from the Royal Veterinary College (one of the top 3 vet schools in the world).

Disclaimer: This website's content is not meant to be a substitute for veterinary care, diagnosis, or treatment. Always consult with your veterinarian to determine the best course of action. Read More.

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