Rashes on Dogs: Prevention and How To Treat Them

Though rashes on dogs aren’t usually an emergency, they can certainly affect your dog’s quality of life.  

If you’re noticing your dog has a rash on their belly or little red spots on their back, you’ve found the right article. 

Here, you’ll learn what causes dog rashes, what you should do if you see a rash on your dog, and how to prevent rashes on dogs. 

What Causes Rashes on Dogs?

When a dog has a rash, the dog usually has a widespread area of skin inflammation.  

This can be in the form of pimple-like red spots, hives, scaly patches of skin, or large, red areas. 

These are the common causes of dog rashes: 

• Allergic reaction: Allergies are one of the most common causes of skin conditions in dogs. You may notice a red or pink tint to the skin, itchiness, or hair loss. Allergic reactions can also cause secondary skin infections, another cause of dog rashes. Skin allergies in dogs are usually caused by environmental allergens (such as pollen), food allergens (usually the protein in the diet), and flea allergies.  

• Insect bites or stings: Insect bites and stings can cause anything from mild pimple-like bumps on a dog’s skin to widespread hives and swelling. If your dog has hives, swelling, and difficulty breathing after an insect bite or sting, they need immediate emergency care. 

• Parasitic infestations: Skin parasites—such as fleas, ticks, and mites—can cause a rash on your dog’s skin. 

• Bacterial skin infection: Bacterial skin infections usually occur because of another skin issue, like an allergy. You may notice pimple-like lesions or red scaly patches on your dog’s skin. 

• Yeast skin infection: Large patches of moist or scaly skin inflammation can be from yeast infections. Common areas affected include the neck, armpits, groin, paws, and ears. Like bacterial skin infections, yeast infections are usually secondary to another condition, like canine skin allergies or hypothyroidism. 

• Ringworm: Ringworm is a contagious fungal infection, not a worm. It can cause scaly patches of hair loss or inflammation on dogs. While it typically forms a ring-like lesion on people, this is not always the case for dogs. Ringworm is contagious to people and other pets. 

• Contact dermatitis: Dog skin irritation can happen after contact with harsh shampoos, certain grooming products, pesticides, detergents, and other chemicals. The rash may be localized to the area of contact or widespread. 

• Underlying health issues: Some underlying conditions—specifically hormonal disorders, autoimmune skin conditions, and cancer—can cause rashes. Of these, hormonal disorders are by far the most common. Common hormonal conditions that can cause rash-like skin issues include hypothyroidism and Cushing’s disease.

• Medication reaction: Like humans, dogs can have allergic reactions to medications or vaccines. If your dog gets hives, facial or limb swelling, or vomiting, or has difficulty breathing after taking a medication or getting vaccinated, it’s best to treat this as an emergency. 

When To Call Your Vet About Rashes on Dogs 

If your dog gets a rash just after a bath or some other obvious cause, it’s okay to manage the rash at home if there are no other symptoms.

For example, if your dog’s skin is a little red after using a new shampoo, your dog might simply need a different shampoo. 

Signs that you should contact a veterinarian include: 

• Pimple-like or round, scaly lesions 

• Hair loss 

• Excessive itchiness 

• Foul or yeasty odor from the skin, ears, or paws 

• Visible parasites, like fleas or ticks 

• Bleeding from the rash 

• Oozing lesions (pus or serous fluid, a thin clear or yellow liquid) 

• No improvement, or worsening after one to two days 

• Painful reaction to lesions being touched 

Most rashes are not emergencies; however, if your dog is getting hives, facial swelling, limb swelling, vomiting, diarrhea, and/or difficulty breathing, they may have anaphylaxis. This is an emergency, and your pet needs immediate veterinary attention. 

How Vets Diagnose the Cause of Rashes on Dogs

Your veterinarian will start with a general physical examination. To help them find the cause of your dog’s skin rash, give the following information to your veterinarian: 

• What parasite preventatives, if any, do you give to your pet? Are other pets in the home on parasite preventatives? 

• Have you recently given any new medications or changed your pet’s diet? 

• When did you first notice the rash? 

• Is the rash accompanied by any other symptoms, such as itchiness? 

• Have you recently changed anything in your home, such as the detergent you’re using or your dog’s shampoo? 

The following tests are most common for skin rashes: 

• Skin scrape. If your veterinarian suspects mites, a skin scrape is the standard in-house test for diagnosis. They will scrape the skin with a scalpel blade and look at the sample under the microscope. 

• Skin cytology. Skin cytology, which involves looking at a sample of skin cells under the microscope, is done to figure out whether there is a bacterial or yeast skin infection. 

• Trichogram. Some veterinarians will look at hairs under the microscope to diagnose ringworm. 

• Culture. A culture may be recommended if your veterinarian suspects ringworm or if your pet isn’t responding to their first medications. 

• Allergy testing. If your pet has skin allergies, intradermal allergy testing (IDAT) is the standard for diagnosing what your dog is allergic to. This involves injecting small amounts of allergens under the skin and watching for a response. IDAT is usually done by a dermatologist. If food allergies are suspected, a trial diet is recommended, usually lasting at least eight weeks. 

• Skin biopsy. A skin biopsy may be recommended if your pet’s skin condition has been unresponsive to treatment or if your veterinarian suspects an autoimmune condition or cancer. 

• Blood work and urinalysis. These tests show if your pet is healthy for treatment, but they can also catch systemic issues that contribute to skin rashes in dogs, such as hypothyroidism or Cushing’s disease.  

Treatment of Rashes on Dogs

Treatment for your dog’s rash depends on the underlying cause but may include any of the following: 

• Specialized or sensitive-skin shampoos. Shampoos may have antibiotics or antifungals. They can also soothe itchy skin and help manage long-term skin issues. Some options include Natural Dog Company Sensitive Skin, Veterinary Formula Clinical Care, and MiconaHex+Triz. 

• Topical antibacterial or antifungal agents: Topical treatments like mupirocin or miconazole may be recommended if your dog’s rash is only in a small area. These may be in the form of a cream or a wipe. 

• Oral antibiotics or antifungals. Antibiotics like cephalexin or oral antifungals like terbinafine will be recommended if your dog has a widespread bacterial or yeast infection. 

• Steroids. Most commonly, this will be oral prednisone. Your veterinarian may give a steroid injection in the clinic, especially if a severe allergic reaction is suspected. Steroids are commonly used for severe allergies, autoimmune conditions, and cancers.  

• Antihistamines. Antihistamines like diphenhydramine are usually not helpful for allergic skin disease, but they’re essential if your dog has hives or other symptoms of a sudden, severe reaction. Some veterinarians may recommend trying antihistamines for mild allergic skin disease before moving to prescription medications or immunotherapy. 

• Medications for hormonal conditions. For hypothyroidism, the most common treatment is the oral medication levothyroxine. For Cushing’s disease, dogs are usually treated with trilostane. 

• Surgery: If your dog has a localized skin cancer or a lesion that isn’t responding to any treatment, surgical removal may be recommended. If cancer is diagnosed, other treatments like chemotherapy or radiation may be recommended. 

How To Prevent Rashes on Dogs

While not all causes of skin rashes in dogs are preventable, the following tips can help protect your dog from skin rashes: 

1. Keep your dog on year-round parasite preventatives to keep fleas, ticks, and mites off your pet. Options include Simparica TRIO, Advantage Multi, and K9 Advantix. 

2. Avoid your pet’s known allergens, whether they’re specific food ingredients or environmental allergens. If your dog has known food allergies, consider a novel protein or hydrolyzed protein diet, such as Royal Canin Selected Protein or Hill’s Food Sensitivities.  

3. Vacuum regularly, use air purifiers (such as the Levoit Core), keep windows closed during allergy season, and change your air filters regularly.  

4. Put pet-safe sunscreen on your dog, especially on exposed areas of skin like the ears or the belly. Options include Gentle Creatures Pet Sunscreen and Emmy’s Best Sun Skin Protector. 

5. Use shampoos that are safe for dogs. Your dog may benefit from a sensitive-skin shampoo, such as Pet MD Oatmeal & Aloe.