Why Does My Dog Keep Chewing His Butt And Tail?

Why won't he stop biting himself?

dog chewing his butt

Dogs can do some pretty weird things sometimes — like chew their butts or bite their tails. Why do they do that?

Turns out there are a lot of causes for itchy butts in dogs, and with the help of your vet, they’re pretty easily treatable.

We spoke to Dr. Megan Moore, a veterinarian at Bergen County Veterinary Center, to find out why your dog is chewing his butt and how to treat it.

Why is my dog chewing his butt or biting his tail?

If your dog is chewing or licking his butt or tail area, there’s probably a reason behind it — he’s likely not just doing it for fun.

“Rectal itching may be due to a variety of issues: full or infected anal glands, intestinal parasites, skin infections, allergies, perianal fistulas or masses, foreign material, trauma, etc.,” Dr. Moore told The Dodo.

Certain factors can put some dogs at greater risk for rectal itching.

“There are predisposing factors that may contribute,” Dr. Moore said. “Overweight dogs, dogs with loose stool or diarrhea, dogs with allergies or rectal conformational issues may have difficulty with natural anal gland expression. Dogs that are not on flea and tick prevention are more prone to external and internal parasites that can cause anal irritation or allergies. Certain breeds, such as German shepherd dogs, have a higher likelihood of immune-mediated illness, such as perianal fistulas.”

Here are some of the main reasons for why your dog might be chewing his butt.

Full or infected anal glands

Dogs have anal glands on either side of their behinds. These glands release their scent, which is how they mark their territory and get to know other dogs — that’s why you might see your dog sniff a new friend’s rear end when they first meet.

If these glands become full or infected, they can be painful or itchy for your dog. If your dog is chewing his tail or scooting (dragging his bottom across the floor), he might have full anal glands that need to be expressed (basically popped) by your vet.

“Not all patients require anal gland expression, as they are supposed to be expressed on their own when defecating,” Dr. Moore said. “A persistent fishy or metallic smell and scooting are signs of dogs expressing their anal glands on their own or having excessively full anal glands that need to be expressed by a veterinarian or technician.”


If your dog is chewing his butt, it can be a sign of parasites, such as tapeworm, ticks or fleas.

Other symptoms to look out for to let you know that your dog might have a parasite include:

  • Weight loss
  • Swollen belly
  • Scooting
  • Dull coat
  • Digestive issues
  • Lethargy
  • Coughing or difficulty breathing
  • Skin infection
  • Anemia
  • Blood loss
  • Flea eggs (these are tiny, white or clear eggs and can look like dandruff or salt in your dog’s fur)
  • Hair loss
  • Scabs and hot spots

Luckily, parasites are easily preventable by making sure your pup is up to date on his deworming medications and flea and tick preventative medications.

Skin infection or irritation

A cut on your dog’s bottom could cause an irritation, or it could even lead to an infection, causing him to itch.

Fleas and ticks can also cause skin infections, itching and hot spots, so be sure to look out for other symptoms, or have your vet check for fleas and ticks as well if your dog has any skin issues.


The most common symptom of allergies in dogs is itchy skin. So if your dog is itching up a storm, he could be having an allergic reaction.

Allergic reactions can have a number of causes, such as flea bites, pollen and even food allergies. If you think your dog might be allergic to something, take him to the vet to find out what he’s allergic to. Your vet will work with you to pinpoint the allergen. Then they might prescribe allergy medication, or you might be able to eliminate the allergens from your pup’s environment.

Perianal fistulas

A perianal fistula is a tunnel in the tissue and skin that surround the anal area of dogs and appears as a hole in the skin.

Signs of perianal fistulas include:

  • Pain and straining when going to the bathroom
  • Constipation
  • Diarrhea
  • Mucus or blood in poop
  • Chewing or itching his butt
  • Reluctance to sit
  • Aggression when someone tries to touch his tail or rear end
  • Behavior changes (depression, aggression, agitation)

German shepherds are thought to be at higher risk because of the position of their tails, which are usually carried low and between their hips, covering their bottoms; however, any breed can be affected.

Foreign material

If your dog has something stuck in or around his butt, such as dirt, poop, grass or something he ate that he wasn’t supposed to, he might be itching the area to try to remove it.

If something is stuck on your dog’s behind, you can remove it if it’s on the outside, but don’t try to pull anything out of your dog’s butt! You could damage your dog’s intestines (and it’s pretty gross). Just let the vet remove it.


If there are no other health problems that seem to be causing your dog’s itchy butt, he could have a compulsive disorder.

Compulsive disorders in dogs are usually triggered by stress, so the best way to treat them is to try to de-stress your dog. Some ways to do this include:

In severe cases, your dog may need prescription anxiety medication. Talk to your vet if you think your dog needs help with his anxiety.

When should you take your dog to the vet for an itchy butt?

If you’re concerned about your dog chewing his butt, the best thing to do is to take him to the vet to get checked out.

It’s time for a visit “if the itching persists for more than 24 hours, the dog is obsessively licking or scooting or you notice irritation, bleeding, malodor, lethargy or other abnormalities,” Dr. Moore said.

Look out for any other symptoms aside from itching, such as other signs of fleas and ticks or allergies, so you’ll know if your dog’s itching is something to be worried about.

How will your vet treat your dog’s itchy butt?

First, your vet will need to determine the cause of the itching.

“The cause of rectal itching is diagnosed by having a veterinarian perform a rectal exam, anal gland expression if indicated, skin exam and fecal parasite screening,” Dr. Moore said. “Based on these initial test results, additional tests, such as biopsies, may be indicated as well.”

Once your vet figures out what’s causing your dog’s itchy behind, they can decide on a treatment from there.

“Treatments are determined by the underlying cause of the itching,” Dr. Moore said.

Treatments include:

  • Full or infected anal glands: “If the cause is full anal glands, then the expression of the glands may be curative until the glands fill again,” Dr. Moore said. “If there is evidence of infection, then antibiotics may be indicated.”
  • Parasites: “A positive fecal intestinal parasite test would necessitate anti-parasitic medication,” Dr. Moore said.
  • Skin infection or irritation: For a skin infection, your vet will probably clean the infection and provide antibiotics.
  • Allergies: “If the itch is related to allergies and generalized itch, then anti-itch medications may be prescribed,” Dr. Moore said. “Some dogs will require steroids as well, depending on the degree of inflammation or if there is an immune-mediated component.”
  • Perianal fistulas: Your vet will likely prescribe anti-inflammatory and steroid medications and possibly antibiotics. Surgery may be required in severe cases, if fistulas are recurring or if oral treatment doesn’t work.
  • Foreign material: Your vet will remove any objects stuck in or around your dog’s butt.
  • Anxiety: For severe anxiety, your vet will likely prescribe anti-anxiety medication and behavior modification techniques. For milder cases, you can try over-the-counter calming products for dogs.

So next time your pup is chewing his butt or scooting across the floor, you’ll know what could possibly be causing it — and you’ll know to keep an eye out for these other symptoms to make sure it’s nothing more serious than just a temporary itch.

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