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Why does my dog have a rash on its armpit?

Just like humans, dogs can develop rashes. There are many potential causes, but they all have one thing in common. They make your poor pooch uncomfortable because they are itchy, and sometimes even painful. 

The good news is that once you know the cause of your dog’s rash, you can take steps to heal the rash. This will provide relief for your pooch. 

Why does my dog have a rash on its armpit?

Your pooch rolls over for a belly rub, and you discover a problem. They have a rash. There are several common causes of dog rashes that can occur on their armpit. 

Heat Rash

If the rash occurs during the summer months, it could be heat rash. Heat rash is a common problem for dogs. As the name suggests, it’s caused by heat. Dogs don’t sweat the way humans do, and this can cause their skin to overheat. 

This is more common in areas where they don’t have hair, including the stomach and the armpit, because these areas are more sensitive. 

Signs of heat rash include redness, itching, and bumps or pimples. The skin may be sore. If the rash is severe, your pooch can develop scabs and a foul odor in the area. 


Allergies are another common dog skin problem. They can be environmental allergies, food allergies, or contact allergies. 

Food allergies occur when your dog eats something they are allergic to. It can cause stomach upset, including vomiting and diarrhea, as well as a rash. In this case, the rash will probably occur in other areas as well. 

Contact allergies are another common culprit. This means your dog came into contact with something they are allergic to. The most common contact allergen for dogs is grass. Others include household cleaners, shampoos, and metal. 

The rash typically appears a few hours after exposure, but can appear a few days after they came into contact with it. The groin and stomach are the most common places these rashes appear, because they are more likely to come into contact with things in these areas. However, the rash can also spread to the armpit. 

Yeast Infection

Yeast infections are a common issue for dogs. Yeast bacteria are naturally on your dog’s skin. When too much bacteria live in a particular area, it causes a yeast infection. 

This type of rash can occur anywhere on your dog’s body, but the stomach, ears, groin, and armpits are common areas. If your pooch has wrinkly skin, infection can also develop in the skin folds. 

In addition to a rash, you will likely notice a sweet, foul, or yeasty odor. This is a good indication that yeast is the culprit. 

A yeast infection is usually a secondary infection. This means there’s another problem that is allowing the yeast bacteria to grow. Causes include allergies, hormonal imbalances, and immune system disorders. 

Bacterial Infection 

Pyoderma is the most common type of bacterial infection in dogs. It can occur anywhere, but it’s most common on the groin or armpits. Like a yeast infection, it can be caused by an underlying condition. Conditions that irritate the skin, like contact allergies, make pyoderma more likely. 

In addition to a rash, pyoderma causes a discharge from the skin. You may also notice bumps or blisters on your dog’s skin.

Poison Ivy or Oak

Plants like poison ivy or oak can also cause a skin rash on your dog. If they get this type of rash in their armpit, it will likely be in other areas as well. 

It occurs when your pooch comes into contact with the plant. It’s unlikely for their armpit to come into contact with it without it touching other areas as well.  As they scratch, it can spread. 

Bug Bites

A bug bite can also cause itching or a rash on your pooch. An armpit may seem like a strange area for a bite, but bites can happen anywhere your dog’s skin is exposed. 

Most bites will cause itching and a red bump in the area. If your pooch is allergic to the bite, it can cause a rash in the area as well. 

What to do if my dog has a rash on its armpit?

 Some types of dog rashes can be treated or managed with home remedies. Others will require veterinary treatment. In most cases, the rash can be cleared with time and proper care. 

Heat Rash 

If your four legged family member has heat rash, you can probably treat it at home. However, if you notice a foul odor or discharge coming from the rash, you should see your vet. 

Cold packs can provide temporary relief. When using a cold pack, be sure that the cold isn’t in direct contact with your dog’s skin. Ice cubes in a washcloth or a store-bought cold pack are good options. Apply for 10 minutes, and then remove. You can repeat this every 4-6 hours. 

Baking soda is another option. Mix a paste by combining equal parts baking soda and water. Apply it to the area. Allow it to sit for 20 minutes, and then rinse with cool water.

Lastly, aloe Vera is wonderful for many skin issues. You can use an aloe Vera leaf or purchase aloe Vera gel. Apply it a few times a day until the rash heals. 

Yeast Rash 

One way to treat yeast rash is with vinegar. You can use apple cider vinegar or white vinegar. Dilute the vinegar by mixing one part vinegar with two parts water. Apply to the area. Repeat twice daily. 

When to See the Vet 

If you suspect your pooch has a bacterial infection, this will require veterinary treatment. If home remedies aren’t improving your dog’s rash, or it gets worse, you’ll need to get them to the vet. 

Allergies also warrant a vet visit. If you can identify the allergen and help your dog avoid it, veterinary care isn’t necessary.

However, they are often difficult to diagnose or avoid. In this case, you’ll need your vet’s help. 

Providing Relief 

Regardless of whether you choose to treat your pooch at home or head to the vet, there are some ways you can give your pooch some relief. These aren’t a substitute for treatment. Instead, they help ease the itching temporarily. 

Hydrocortisone cream is safe for dogs. It can provide itch relief and speed healing of the rash. There are hydrocortisone creams made for dogs, but the human version is also considered safe. Just don’t allow your pooch to lick a large amount of the cream. 

Oatmeal baths are another way to help your pooch feel better. You can purchase oatmeal bath flakes, or make your own by grinding plain oatmeal. Oatmeal baby cereal is another option. The tiny flakes dissolve in water, making clean up easy. 

Just run a lukewarm bath for your pooch, and add the oatmeal. Allow the affected area to soak for 10 to 15 minutes, and then dry your dog. It’s not necessary to rinse the oatmeal, unless you notice undissolved pieces on your dog’s skin or coat. 


Coconut oil and olive oil are great for your dog’s skin. Coconut oil has the added advantage of having antifungal and antibacterial properties. Both will moisturize the area, which can aid healing and provide itch relief.