✔️Article written by a veterinarian & reviewed by Dr. Whittenburg, director, on Nov 30th 2022.
Complicated doesn’t 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 isn’t meant to scare you, just to make you aware that skin issues are many and wide-ranging in dogs. So, let’s take a look at the 21 most common skin conditions, problems, and diseases, so you’ll be better at recognizing them and getting them treated.
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. Moist Dermatitis (Hot Spots)
Hot spots, technically known as acute moist 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 and under the ear, legs, and on the hips. The area will be moist and typically have some purulent oozing. Often there is matted fur covering and hiding the hot spot. Though not life-threatening, these lesions can make dogs absolutely miserable. Hot spots are caused by retained moisture in the hair or an irritant against the skin.
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 on dogs.
2. Environmental Allergies and Allergic dermatitis
Allergies to substances in the environment (atopy) can manifest as skin lesions in dogs. In a dog that suffers from atopy, the dog’s immune system overreacts to an airborne or contact allergen in their environment. 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 set up secondary infections, resulting in further damage to the skin. You’ll most often find allergic dermatitis on the lighter-haired parts of the body, such as the belly, groin, and armpit.
Atopy is best treated by determining the allergen and removing it from the environment. When this isn’t possible, prescription allergy medications and anti-inflammatories are used.
WATCH: 3 Important Tips To Care For an Old Dog [VET VIDEO]
Dermatitis Photo Gallery:
3. Food allergy skin rashes
Food allergies in dogs present differently than environmental allergies. Food allergies tend to manifest as itchy paws, itchy skin, chronic ear infections, or as 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 see 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’s important to find a new diet that doesn’t contain that ingredient and stick to it to prevent further flare-ups.
There are two main types of mange that affect dogs, demodectic and sarcoptic. Demodectic mange 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, 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.
5. Flea allergy
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.
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.
8. 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 fur grows. 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 vet cannot diagnose skin issues in people, but knowing this might help their diagnosis or suspicion of ringworm in your dog.
3. Yeast skin infections
Yeast skin infections are another form of fungal infection. Malassezia is one of the most frequently seen in 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 dog skin infections.
Dog Skin Conditions Category 3: Lumps and bumps
1. Lipomas on Dogs
Lipomas are the most common benign (ie 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’re generally easy to move around and don’t feel as though they are connected to deeper tissue in the body. Lipomas are usually slow growing. Sometimes they will stop growing, but don’t often disappear or get smaller. Although these common old dog lumps are not dangerous in themselves, if a lipoma gets too big, it can cause discomfort for your dog and may need to be removed. Learn more about lipomas in dogs.
2. Dog Warts
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, paw pads, between the toes, around the genital area, or in the mouth. 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 7 pictures of dog warts.
3. Sebaceous Cysts
Sebaceous cysts are not just old dog lumps. They’re 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. 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.
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 aren’t without a needle aspiration biopsy. Single tumors that haven’t 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 and view more pictures.
Melanoma tumors are dark and can be small, large, flat, or raised. 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.
6. Squamous Cell Carcinoma
Squamous cell carcinomas in dogs are the second most common type of cancer in the mouth. 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.
7. 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.
8. Anal Gland Tumor (Adenocarcinoma)
Anal gland tumors 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.
Click here to learn more about lumps and bumps in dogs.
Other common dog skin problems and conditions
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.
Black spots on dog skin (Hyperpigmentation)
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 on a dog’s skin.
Dog Skin Problems and Conditions by Category:
- Lumps and bumps (and red lumps and bumps)
- Tumors, Warts, or Cysts
- Scabs or blood blisters
- Skin lesions or skin infections
- Cancerous lesions or lumps
- Skin allergies and rashes, heat rashes, hot spots
- All skin problems and conditions
Disclaimer: This website's content is not a substitute for veterinary care. Always consult with your veterinarian for healthcare decisions. Read More.