Dog’s Hair Loss Patch / Bald Spot: What is it? [Vet Advice]

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patch of hair loss (tail gland bump)

This article was updated on August 3rd, 2023

I have been practicing as a small animal veterinarian for almost two decades and one very common issue that my patients present with is patchy hair loss. There can be many causes for this type of hair loss and diagnostics will likely be needed to confirm the cause and determine an appropriate treatment.

In this article, I will discuss the most likely reasons and what you should do to help your dog.

Key highlights:
– There are many causes of patchy hair loss in dogs. Luckily, most are not serious and can easily be treated.
– Top causes include hotspots, parasites, skin infections and conditions like Cushing’s disease.
– If your dog’s hair loss patch is isolated and your dog acts normal, you may monitor it and call your vet if it gets worse.
– Call your vet if you see other signs of discomfort or illness, such as itchiness or an irritated skin.

Dr. Jamie Whittenburg

Veterinarian Director at

My dog has a new patch of hair loss – is it serious? 

There are many possible causes of patchy hair loss in a dog. Luckily, most of these causes are not serious and can easily be remedied with proper treatment. Let’s review the most likely causes (with pictures).

If your dog is also itchy, read our article about Itchy Dogs Losing Hair.

Top causes of bald spots in dogs

Below are the most common causes of new patches of hair loss in dogs:

1. Hot Spot (Moist Dermatitis)

Hot spots are red, typically moist, patches of hair loss due to irritation. They can occur anywhere on the dog, but are most common behind the ears and on the rear end/hip area.  

Anything that causes the dog to scratch and lick at their skin can cause a hot spot. The two most common causes are ear infections and allergies. The area will be inflamed, may have matted hair over it or around it, and may have a purulent discharge and foul smell.  

Untreated, hot spots will make your dog miserable as they are painful and extremely itchy. The spot will also likely grow in size as it continues to irritate your dog. Though a hot spot is not an emergency, it is urgent as the spot and the underlying cause will need to be addressed and treated. 

At home, while waiting for your dog’s veterinary appointment, you can help the spots from getting worse by putting a t-shirt or baby onesie on them to discourage licking and scratching. Keep your dog inside in a cool area with plenty of fresh water.  Learn about the best remedies to treat hot spots at home.

When your dog is seen by the veterinarian, typically the area around the hot spot will be shaved and the spot may be cleaned. Antibiotics, anti-inflammatories, and allergy medications may all be necessary to control the dermatitis. Learn more about hot spots on dogs with pictures and veterinarian advice.

2. External Parasites (mites and fleas)

Mites and fleas may cause hair to fall out in patches, and the lesions may be red, inflamed, and itchy, or simply hairless. Besides bald spots, fleas in dogs often cause itching, redness, and small black dots (flea dirt) on the fur. Mites can lead to crusty skin, and intense scratching.

Fleas can often be seen running along your dog’s skin if you part the hair or comb it backwards. They are very small, black to dark brown insects that run and jump; they are not attached to the skin. View more pictures of flea allergy issues in dogs.

Mites are another common cause of patchy hair loss and cannot be seen with the naked eye. See image below or click here to view more pictures of dog mites (Mange or Scabies).

If you suspect that your dog might have external parasites causing their patchy hair loss, they need to be seen by a veterinarian for a proper diagnosis and treatment.

At home, while awaiting your appointment, you can try bathing the dog in water with a small quantity of mild dish detergent if you suspect fleas, or a soothing dog shampoo with oatmeal to relieve discomfort and itching. 

Your dog’s veterinarian will use a flea comb to identify fleas and a deep skin scraping under the microscope to identify mites. Depending on which parasite your dog is infested with, the doctor will advise you on proper treatment and prevention for the future.

Disclaimer: This content is not a substitute for veterinary care. Always consult with your vet for health decisions. Learn more.

3. Fungal Infection (Ringworm)

ringworm on a dog
Hair loss due to ringworm in a Jack Russell dog

Despite the name, ringworm isn’t a worm at all. This circular hair loss is caused by a fungal infection and is contagious to other animals as well as humans. Typically, these lesions are round in shape with a hairless center, and they grow larger in a concentric fashion. 

ringworm fungal infection with patches of hair loss
Ringworm infection with patches of hair loss and irritated skin

Dogs suspected of having ringworm should be seen by their veterinarian as soon as possible to ensure that the diagnosis is accurate. Ringworm needs to be treated promptly and appropriately to keep it from spreading to other animals, humans, or contaminating the pet’s environment. It is also important to evaluate the dog’s overall health and immune function, as being affected by ringworm may indicate a deeper, more serious issue with their immune system. 

At home, before their veterinary appointment, you can provide some comfort to your dog with suspected ringworm by bathing them with a soothing oatmeal shampoo.

The dog should be kept isolated from other pets and the family as this is a contagious disease. Owners should wear gloves when handling the pet. 

Your veterinarian will use a combination of history, lesion appearance, Wood’s Lamp illumination, and fungal cultures or testing to diagnose your pet with ringworm. They will prescribe appropriate medications and advise you if further medical testing is necessary. 
View more pictures of ringworm in dogs with our veterinarian team’s advice.

4. Hyperadrenocorticism (Cushing’s)

Dogs affected with Cushing’s disease typically have a pot-bellied appearance, patchy hair loss (especially on the tail), and other signs such as panting and excessive drinking. 

hair loss on dog with cushing's disease
Dog’s hair loss due to cushing’s disease

Diagnosing Cushing’s can be difficult, but this disorder can be fatal if left untreated. There is no home remedy or treatment for hyperadrenocorticism. If you are concerned your dog may be affected, they need to be seen by their veterinarian as soon as possible. 

If blood testing confirms Cushing’s, your veterinarian will guide you through appropriate treatment. Most dogs are treated with lifelong daily medications and will require frequent medical monitoring. 

5. Seasonal Flank Alopecia

Seasonal flank alopecia is most often seen in bulldog breeds and Boxers. The hair loss tends to occur on either side of the dog’s abdomen, in the flank area, as shown on the picture below.

flank alopecia in dog
Photo: © Ian Brett Spiegel VMD, MHS, DACVD

Click here to view another picture from The skin is not affected and the condition is not itchy. This disorder is most typically seen in the winter months in the United States. 

The most important thing to do if you suspect this condition in your dog is to have a veterinarian rule out other causes. Seasonal flank alopecia itself is a benign condition and rarely requires treatment. However, it can easily be confused with other less benign conditions such as hypothyroidism and hyperadrenocorticism, which require treatment. 

Steps to take at home if your dog has a new patch of hair loss 

If your dog’s patchy hair loss is causing them discomfort you should:

  • isolate your dog
  • enact methods to keep your dog from scratching or licking the area (for example using an e-collar)
  • make an appointment with your veterinarian as soon as possible.
  • give your dog a warm bath with a soothing oatmeal shampoo (this may be temporarily helpful)

Frequently Asked Questions  

1. Are dogs with a new patch of hair loss more likely to keep losing hair? 

Whether or not the dog is going to continue to lose hair depends entirely upon what is causing the hair loss. However, most conditions will worsen without appropriate treatment. 

2. Do some conditions start with a single bald spot before getting worse? In those cases, how fast does it progress? What should dog owners keep an eye for? 

Yes, it is common for some of these conditions to begin with a single, small patch of hair loss. How quickly the condition will progress depends on the underlying cause. Owners should try to have their pet seen by a veterinarian as soon as possible to decrease their discomfort and to make treatment easier. 

3. What are the signs that an appointment at the vet is needed? 

Any unexplained patchy hair loss warrants a visit to the veterinarian. Because our pets cannot talk and express their discomfort, often problems are left untreated for too long. This results in not only unnecessary discomfort for the dog, but also results in treatment being longer, more expensive, and more involved than it would have been had the condition been addressed earlier. 

Veterinary help with bald spots and hair loss in dogs 

When you take your dog with patchy hair loss into the veterinarian, they will begin by taking a detailed history and performing a thorough physical examination. Depending on the suspected cause of the hair loss, your dog may require skin scrapes, biopsies, fungal cultures, or blood testing. These procedures tend to cost between $100-$500. Treatment varies widely, dependent on the cause, but can add $50-$200 to the initial visit.  

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  • Dr Whittenburg, Hospital Director

    Dr. Jamie Whittenburg is a Veterinarian Director at 'Senior Tail Waggers' and Director and Owner of Kingsgate Animal Hospital, a full-service animal hospital in Lubbock, TX. She graduated from Kansas State University's College of Veterinary Medicine (DVM) and has over 17 years of experience working as a veterinarian & hospital director.

Disclaimer: This website's content is not a substitute for veterinary care. Always consult with your veterinarian for healthcare decisions. Read More.

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