Pictures of 21 Common Dog Skin Problems [with Vet Advice]

This article was updated on August 10th, 2023

Complicated does not even start to describe a dog’s skin. It does many important jobs and can show up with many often-confusing conditions, problems, and diseases. This is not meant to scare you, just to make you aware that there are many wide-ranging skin diseases in dogs. In this article we will review pictures of the most common skin conditions affecting dogs – with veterinarian comments from our veterinarians: Dr. Chyrle Bonk & board-certified veterinary dermatologist Dr. Ian Spiegel.

Dog Skin Problems Category 1: Skin Allergy, Parasites, and Internal Conditions

The bumps and rashes that you may see on dogs vary, and their appearance can often give clues to their cause. Some of the most common include:

1. Hot spots

Hot spots (technically known as acute moist dermatitis or pyotraumatic dermatitis) are red, inflamed areas of skin that can seem to appear overnight. These spots may occur anywhere on a dog but are most common behind/under the ear, neck, cheek, legs, and hips. Often there is matted hair covering and hiding the hot spot. Though not life-threatening, these lesions can make dogs miserable. Hot spots are caused by retained moisture in the hair or an irritant against the skin. The skin is macerated, red, irritated, and moist with purulent (pus) oozing on the surface. The affected skin is friable and easily bleeds. Common scenarios include recent swimming or bathing with inadequate drying of the hair coat.

The hot spot will need to be clipped and cleaned. Antibiotics and anti-inflammatories are used to treat infections and remove the itch. These may be applied topically or given orally. View more pictures of hot spots or learn about the best remedies for hot spots.

2. Environmental allergies (atopic dermatitis)

Allergies to substances in the environment (atopy) can manifest as skin lesions in dogs. In atopic dogs, dog’s immune system is dysregulated and overreacts to airborne or contact allergens. This overreaction produces skin inflammation in the form of itchiness, redness, and heat. Excessive rubbing and irritation can lead to hair loss and the breakdown of the skin barrier which allows bacteria to overpopulate and cause secondary infections, resulting in further damage to the skin barrier.

You will most often find allergic dermatitis on the lighter-haired parts of the body, such as the belly, groin, and armpit. Atopic disease is managed, not cured. Atopic dermatitis is best managed using a multimodal approach. There are tests available to help determine which allergens should be incorporated into the allergen-specific immunotherapy (e.g., allergy shots or sublingual dosing). Avoidance is usually not effective as a sole approach, but you should still try removing the allergen from the dog’s environment. When this is not possible, prescription allergy medications (cyclosporine, oclacitinib, and lokivetman) should be considered. Learn more about skin allergy issues & rashes in dogs.

3. Food allergy skin rashes (cutaneous adverse food reaction)

Cutaneous adverse food reactions can cause itchy paws, itchy skin, chronic ear infections, or gastrointestinal issues such as diarrhea. Another distinguishing feature is that food allergies tend to occur year-round, in contrast to atopy, which is typically seasonal.

To diagnose a food allergy, your veterinarian will have you feed either a limited ingredient, hydrolyzed, or a novel protein diet to your dog for at least eight weeks. This is called a food trial. It is essential not to feed your dog anything else during this trial, including treats and flavored medications. It may take the entire eight weeks to notice a difference, so do not stop early. If/once an ingredient is pinpointed that a dog is allergic to, typically a protein source in the food, it is important to find a new diet that doesn’t contain that ingredient and stick to it to prevent further flare-ups. Learn more about food allergies in dogs.

4. Mange

There are two main types of mange that affect dogs, demodectic and sarcoptic. Demodectic mange (Mites) is caused by the ‘Demodex’ mite and most commonly causes patchy hair loss in younger dogs. This condition is not itchy and not contagious. Sarcoptic mange (Scabies), caused by ‘Sarcoptes’ mites, is very itchy and is contagious to both other animals and humans. Diagnosing mange in dogs involves a veterinarian scraping the hair follicles and examining the scraping under a high-power microscope to try to spot the bugs. Mange is treated with parasiticides. View more pictures of dog scabies and dog mites with advice from our veterinarian team.

5. Flea allergies

Fleas can cause all dogs to bite and scratch themselves. However, some dogs are truly allergic to fleas and may have an allergic reaction to the flea’s saliva when they bite. Flea allergy dermatitis typically presents as a red, inflamed, and scabby hind end, just above the base of the tail. Fleas may or may not be found. Treatment for flea allergy dermatitis consists of immaculate flea control, antibiotics for secondary infections, and anti-inflammatories. Over-the-counter flea preventatives are available but are often ineffective and can be unsafe. Flea collars tend to rid the dog of fleas on their neck but not in other areas. Reactions are also common with these over-the-counter collars. Ask your veterinarian which flea preventative is best for your dog. Read our article: Easy Ways to Tell if Your Dog Has Fleas or view more Pictures of Flea Allergies & Flea Scabs in Dogs.

6. Endocrine disease/hypothyroidism

Hypothyroidism and many other endocrine diseases can result in hair loss and skin rashes in dogs. The hair loss is often in a particular symmetrical pattern across the dog’s sides that may give your veterinarian an idea of the issue. Blood tests and skin scraping will help diagnose the specific issue. The treatment for endocrine disease varies with the disease. Hypothyroidism is treated with daily supplementation medication. There is no home treatment for endocrine disease. If you suspect your dog may be hypothyroid or have another endocrine issue, make an appointment with your veterinarian as soon as possible.

7. Autoimmune disease

Autoimmune diseases can result in redness, inflammation, and crusting of the skin. Most commonly, the skin around the nose, mouth, and eyes is affected first. Diagnosis consists of a skin biopsy that will be interpreted by a veterinary pathologist. Learn more about dog skin allergy issues.

Dog Skin Conditions Category 2: Skin Infections

We can break down skin infections in dogs into bacterial and fungal causes. In more severe cases, your dog may have both! 

1. Bacterial skin infections

Staphylococcus species typically cause bacterial skin infections. These infections often cause redness, pustules, and discharge. You may also notice your dog itching, chewing, or excessively licking. Infections in the skin’s most superficial or outer layers may be treated with topical antibiotic creams, ointments, or sprays. Bacteria that have penetrated into the deeper layers of the skin may need oral antibiotics to reach those tissues. For example, folliculitis is a bacterial infection of the hair follicles from which your dog’s hair grows (see picture above). This results in sores, scabs, and bumps with the follicles becoming inflamed.

In the two pictures below, you can see scabs, redness, and flakes on a dog’s skin, due to bacterial infections:

2. Fungal skin infections

While there are multiple fungal infections, the one that strikes worry in most pet owners is ringworm, caused by Microsporum species. It causes hair loss and scaly patches of skin, but it is not always in a “ring” presentation. This surprises many people since the infection has a more characteristic round or ring appearance on people. See our article with pictures of ringworm in dogs.

Despite the name, ringworm is not, in fact, a worm. Ringworm is a fungal infection that is contagious between animals and humans. The lesions are typically circular with hair loss widening concentrically outwards. The very outer ring is often scaly. Dogs may have one lesion or up to hundreds.

Let your veterinarian know if any person in the home has recent skin issues, especially with a ring or round appearance. Remember, your veterinarian cannot diagnose skin issues in people, but knowing this might help their diagnosis or suspicion of ringworm in your dog. View more pictures of fungal skin infections, selected by our veterinarians.

3. Yeast skin infections 

Yeast skin infections (Malassezia) are another form of fungal infection. Malassezia is one of the most frequently seen skin infections, especially in ears, skin folds, and paw pads. Yeast has a distinct musty or sour smell. In chronic cases, yeast infections often cause skin thickening.  Depending on the severity, these infections can be treated with oral or topical medications. Learn more about yeast skin infections.

Dog Skin Conditions Category 3: Lumps and bumps

1. Lipomas

Lipomas are the most common benign (NON-cancerous) growth seen in dogs. Each lipoma is made up of a group of fat cells that forms a soft round, or oval, lump usually located just below your dog’s skin. They are generally easy to move around and do not feel as though they are connected to deeper tissue in the body. Lipomas are usually slow growing and tend to be harmless. Sometimes they will stop growing, but don’t often disappear or get smaller. Although these common lumps are not dangerous in themselves, lipomas getting too big can cause discomfort for your dog and may need to be removed. Although these common old dog lumps are usually not dangerous, larger lipomas can cause discomfort or compromise mobility (e.g., infiltrative lipomas). Depending on where they are located, lipomas can cause also cause put pressure on internal organs. Learn more about lipomas in dogs.

2. Dog warts and adenomas

Warts (also called papillomas) are the other most common type of old dog lumps and can occur on your dog’s skin, on his eyelids, ear flaps, paw pads, between the toes, around the genital area, or in the mouth or lips. They can show up as a single small lump, or as a group or cluster of tiny lumps which look a little bit like a cauliflower floret.

Warts on dogs are most often benign and will often disappear of their own accord after a few months. Some can become irritating and cause a dog to bite or chew at them. These may be better off removed to prevent further damage to a dog’s skin. Very rarely they can become cancerous, so any wart that is a long-term issue, or that changes in color/size/look needs to be investigated by a vet. View more pictures of dog warts with veterinarian advice.

Pictured below are sebaceous adenomas. These growths tend to grow outward on to the skin surface. They are narrower at the base and are often on a thin stalk. The growths are usually 4mm to 10mm in size and sometimes they might extend below the surface of the skin. Removal is usually curative, but removal is not usually necessary unless it is getting infected or irritated (sometimes self-mutilation).  The prognosis is usually good. Learn more about Sebaceous Adenomas.

3. Follicular (Sebaceous) Cysts

Sebaceous cysts are common in dogs of all ages and can occur singly, or your dog could have several of them. These types of cysts can be tiny or grow up to an inch or more in size, as shown on the pictures below.

They tend to resemble a human ‘pimple’, just larger. Sebaceous cysts contain a thick, dark-colored liquid that may ooze out if they rupture. If sebaceous cysts are bothering your dog, your vet may advise surgically removing them. Learn more about sebaceous cysts in dogs or view the different types of cysts in dogs.

4. Mast Cell Tumors

In healthy dogs, mast cells are the part of the immune system that releases histamine in response to allergies. Sometimes, these mast cells can clump together forming a lump in the skin. Occasionally, they can pop up in the liver, spleen, or in the intestine.

Mast cell tumors are more often seen in middle-aged and older dogs but can affect younger dogs too. These dog lumps are not always malignant, but it’s impossible to know which ones are and which are not without biopsy. Single tumors that have not spread are surgically removed. Tumors that spread may require surgery and additional chemotherapy. Drugs are being developed that will specifically target and kill mast cell tumors as well. Learn more about mast cell tumors with more pictures & veterinarian advice.

5. Melanoma

Melanoma tumors are dark and can be small, large, flat, or raised. They can appear as a solitary smooth surfaced pigmented nodule, a multilobulated nodule, or even somewhat flat. They can be either benign or malignant, so they shouldn’t be ignored. If a dog has malignant melanoma, it’s usually an aggressive cancer which spreads throughout the body quickly, so the lesion needs to be surgically removed as quickly as possible. Only a veterinarian can tell the difference between a benign and a malignant melanoma by doing a biopsy. Most malignant melanomas in dogs grow in/around the mouth or in other mucus membranes, but they can also be found in other areas.

6. Squamous Cell Carcinoma

Squamous cell carcinomas in dogs are rare, and they are not as aggressive in terms of spreading—usually focally. However, like some aggressive melanomas or high grade mast cell tumors are, these can spread (metastasis). They can also occur on the skin and nail beds. They are not as aggressive in terms of spreading as melanoma or mast cell tumors are. These types of malignant tumors are usually found on areas of skin that are bare, or have little hair, and are more common in dogs with light-colored skin. Squamous cell tumors in dogs can be raised lumps or nodules, or flatter areas of ulcerated skin. They can sometimes resemble adenomas as well as warts.

7. Hemangiosarcoma/Hemangioma Tumors

Hemangiosarcoma is a malignant cancer of the cells that line the blood vessels of the body. Therefore, hemangiosarcoma can occur anywhere in the body where blood vessels are found. In the case of hemangiosarcoma, the cells that line the blood vessels start dividing uncontrollably and in an unhealthy manner. This leads to the development of a mass that is very prone to rupture and can even cause a dog to bleed out internally. Luckily, what is usually found on the skin are benign blood vessel tumors known as melanocytomas. These are benign blood vessel growth. They may even be in part induced by extended periods of solar exposure. Read more about hemangiosarcoma in dogs.

8. Mammary gland tumors

Mammary gland tumors can be cancerous or benign. They are often located next to or beneath the nipple and may extend between multiple mammary glands. They are firm and may have ulcerated skin overlaying or be abscessed/bleeding. Due to the lymphatic drainage that links mammary glands together, these tumors can spread quickly to the other mammary glands and even to the rest of the body. Therefore, quick surgical removal is recommended. Spaying a female dog significantly reduces their risk of developing mammary gland tumors. View more pictures of mammary gland tumors, with veterinarian advice.

9. Anal sac tumor

Anal sac tumors (adenocarcinoma) are growths on a dog’s anal glands. They show up as lumps next to the dog’s anus. They are firm and can be ulcerated or infected. Dogs may have difficulty defecating due to the size and pressure on the rectum and anus. Anal gland tumors are nearly always cancerous, grow quickly, and can spread. Anal gland tumors can be surgically removed, but radiation or chemotherapy may be required to remove leftover cells.

Learn more about lumps and bumps in dogs.

Other common dog skin problems and conditions

Hair loss

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 hair loss (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 veterinarian. Read our veterinarian articles about hair loss in dogs.

Black spots on dog skin

Most instances of dark or black colored spots on the skin of dogs are hyperpigmentation. Hyperpigmentation occurs when there is an increase in dark pigmentation of the skin. Most commonly, the dark or black spots, along with the other signs of redness, scaling, crusting, and itchiness, are secondary to trauma or chronic irritation. Allergies, parasites, injuries, and other things may all cause skin irritation and itching, leading to hyperpigmentation. Learn more about black spots or brown spots on a dog’s skin or on a dog’s belly.

Dog Skin Problems and Conditions by Category:

• Lumps and bumps (including red bumps and black bumps)
• Tumors, Warts, or Cysts (6 Types of cysts in dogs)
• Scabs and blood blisters
• Skin lesions and skin infections
• Cancerous lesions or lumps
• Skin allergy rashes, heat rashes, hot spots
• All skin problems and conditions