My Dog Keeps Biting Its Bum and Tail. Why?

You’re likely concerned if you’ve noticed your dog suddenly biting their bum and tail, but this behavior is more common than you might think. It is still, however, the sign of a problem and shouldn’t be ignored. So why does your dog keep biting their bum and tail?

Two of the most common causes of a dog biting its bum and/or tail are fleas and blocked anal glands. Both can be treated fairly easily. But be sure you address either situation quickly, especially if you notice bleeding, as neglecting to do so can create more complicated health issues like hot spots.

Let’s take a look at why dogs may bite their bum and tail, and what to do about it. We’ll also explore how to keep our dog from biting and chewing themselves until the cause is resolved

Do I Need to Take My Dog to the Vet?

First and foremost, you should never make assumptions about the cause of your dog’s behavior. If you notice your dog biting their tail or the base of their tail until it bleeds, you should get immediate veterinary advice and assistance. 

Other signs of a need for immediate vet intervention include any symptoms of infection:

  • Redness and itchiness
  • Pus-like discharge
  • Fur loss with moist skin
  • Crusty or peeling skin
  • Fever

Any wound your dog suffers may quickly get infected, and this can end up in a dangerous or even lethal situation. 

However, if your dog is simply irritated and is biting their tail, there are several reasons as to why they may be doing this.

Why Your Dog May Be Biting Their Tail

Parasitic Infestations

There are several kinds of parasitic infections that can cause tail or bum biting behavior in dogs. Some of the most common culprits are fleas, worms, and ticks. Your dog may have more than one kind of parasite. 

Fleas are a type of parasite that causes itching for your dog. One area where fleas will often live is at the base of your dog’s. Once a flea bites your dog, your dog may then have an allergic reaction to the flea’s saliva. This is called flea bite dermatitis and is actually what causes the most discomfort to dogs, and why they bite their bum and tail.

If you think your dog might have any parasitic infestation, get advice from your veterinarian. Most types of parasites are easy to deal with with a short course of medication. For instance, if your dog has tapeworm, the vet will give them a dewormer. For fleas, there are a number of topical and oral medications.

Lastly, you should always get a prescription from your veterinarian. Don’t try to treat parasites on your own, or you may risk recurring infestations.

An Issue With Their Anal Glands

Swollen or blocked anal glands are a frequent cause of bum biting and chewing. There are glands at each side of your dog’s anus. It’s quite common for these glands to get blocked or inflamed, causing discomfort to your dog. This is a painful condition and can often result in infections. 

A common symptom that accompanies anal gland swelling or blockage is a strong fish smell. It’s a very strong, distinct odor and often a strong clue as to the cause of your dog chewing on their butt.

If you think your dog might have impacted or infected anal glands, bring them to the veterinarian. Your vet will be able to get rid of the blocked material by expressing the glands. 

Professional dog groomers will also perform this simple (but disgusting to many!) procedure. And you can learn to do it yourself, if you so choose. Some dogs need to have this done regularly, while others can go a lifetime without needing it.

An Injury

Another cause of your dog biting their tail may be due to an unnoticed injury.

If your dog has injured themselves and there is a wound or skin irritation, this may lead to constant bum or tail biting. Make sure to examine your pet for any open wound and go to the vet for timely treatments.

An injury can lead to what is called a “hot spot.” The term hot spot is used to describe a condition called acute moist dermatitis. When your dog has a hot spot, it means there is an area of skin where there is inflammation and bacterial infection. 

A hot spot isn’t always large. In fact, they’re often very small at first. You might even think that a hot spot is an insect bite.

If your dog has a hot spot, it will usually get bigger and worse over time. If untreated, hot spots will end up as potentially dangerous lesions. 

A hot spot may be the reason why your dog is continually biting its tail or bum. However, your dog constantly biting that area for any other reason may also actually lead to a hot spot developing. A dog biting and chewing at any small wound can create a much larger hot spot very quickly.


Dogs can be allergic to all sorts of things, including ingredients in their food, environmental allergens such as grasses and pollens, and manmade allergens like laundry soaps. And as noted above, if your dog has a flea allergy, this may lead to more severe reactions to bites. 

Food allergies are quite common, and it’s difficult to narrow down the precise ingredient that doesn’t agree with your dog. The process usually includes what is called an elimination diet to determine the offending ingredient.

Chewing on the tail is a common symptom of food allergies. If you suspect a food allergy may be causing this unwanted behavior in your dog, take careful notes of everything your dog consumes in its diet and contact a vet for further guidance. 

A vet’s recommendation often involves switching to a food with a novel protein and seeing if the dog reacts better to that diet.

One thing you can try before going to a vet is feeding your dog a higher quality food that doesn’t have lots of fillers like corn. Many dogs have strong allergic reactions to corn fillers that are used in inexpensive dog kibbles.

Anxiety / Emotional Biting

Sometimes dogs will start engaging in self-destructive behavior if they are bored, stressed, or if they feel anxious.

If you think this may be the cause of your dog’s unwanted behavior, take steps to alleviate the issue. For example, if your dog is anxious, spend more quality time with them by walking, cuddling, or giving them massages. Merely providing adequate exercise has solved a lot of issues for dogs.

How to Help Your Dog Stop Biting Their Tail

While you may need to get veterinary attention for your dog to stop whatever is causing them to bite their bum or tail, you can also take immediate action to try to stop the behavior. 

Simply saying “no” when they begin to bite their tail and then rewarding them with a treat when they stop biting will teach them the behavior that you desire. It’s then up to you to supervise and correct them when they start.

Obviously, this only works when you are present, but it can help slow down or stop a hot spot from developing while you are addressing the root cause.

Elizabethan collars or cones may seem like an extreme measure, but if it keeps your dog’s bum or tail from developing an infection as a result of your dog’s biting, it is worth the hassle and frustration that your dog will probably feel.

If there are behavioral triggers of your dog’s tail biting, you need to try to remove them. It might be a stressful situation or a person or animal that makes your pet uncomfortable.


While some biting can be normal, if you think your dog is biting their tail too frequently, or if they show any signs of bleeding, infection, or parasites, then it’s likely time to call the vet.

There are plenty of reasons as to why your dog may be biting their own tail. If you and your vet can’t determine a physical reason, it may be something psychological that is causing their behavior.

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