My Dog’s Butt Smells Like Fish [Explained]

If you’ve begun to notice that your dog’s backside has a strange, fishy odor, there’s no immediate cause for alarm, but it’s still good to know what’s causing the smell and what you can do about it. 

my dog's butt smells like fish
Help! My dog’s butt smells like fish. Why?

The fishy smell emitted from your dog’s butt comes from their anal glands, sometimes referred to as anal sacs, which are a normal and healthy part of a dog’s anatomy. However, these sacks should empty themselves over time, and if you’re noticing a smell, it could indicate a buildup of the fluid these glands produce, or, in some instances, it may indicate a more severe problem. 

In this article, I’ll discuss in greater detail why your dog’s butt may smell like fish, whether or not you should be concerned if your dog’s butt smells like fish, and what to do about it if you notice a fishy smell coming from your dog’s backside.

Why Does My Dog’s Butt Smell Like Fish?

a long haired chihuahua
A long-haired Chihuahua living its best life outdoors

If you’re a first-time dog owner or your previous dog didn’t have this problem, your dog’s butt all of a sudden smelling like fish can be alarming. However, several factors could be contributing to your dog’s odor problem.

Firstly, some dogs are genetically predisposed to having issues with anal gland expression; commonly, smaller dog breeds such as chihuahuas have problems with this. 

Other factors that could be contributing to your dog’s inability to express their anal glands appropriately are their weight and other medical conditions such as hypothyroidism. 

Obese dogs are more likely to have issues expressing anal glands, so proper diet and exercise are essential factors in reducing this fishy smell (so long as this is the underlying cause of their issue).

To better comprehend how vital anal gland expression is, it’s essential to understand what anal glands are and their function in a dog’s body. 

What Are Anal Glands?

a German shepherd at the vet
A German Shepherd at the Vet.

Anal glands are small sacs positioned under the skin on either side of your dog’s anus. They store a fishy-smelling fluid that is naturally released into your dog’s anus through tiny ducts as your dog defecates.

This fluid marks your dog’s feces with a distinct smell that is entirely their own. Although imperceptible to us, dogs can recognize the difference in these scents, which is why they’re so interested in sniffing each other’s hind ends upon meeting as well as smelling other dogs’ feces. 

When you smell a fishy odor coming from your dog’s hind end, it indicates a buildup of fluid in their anal sacs, which several things could cause. 

You’ll want to get to the underlying cause of your dog’s anal gland buildup with your vet. If it’s something as simple as genetics, this may require a regular manual expression of their anal glands. 

However, the underlying cause may be more severe and treatable, in which case, you’ll want to work on a plan with your vet to remedy the issue.

Is There Anything I Can Do to Keep My Dog’s Butt From Smelling Like Fish?

Several contributing factors may be causing your dog’s anal gland buildup. While many of these factors are out of your control, you can take some preventative measures to try and mitigate these issues. 

First and foremost, diet and exercise are essential not only for your pet’s overall health and wellbeing but for their ability to express their anal glands naturally.

Keep your dog on a consistent, healthy diet with an appropriate amount of fiber to promote regular defecation.

You should also regularly exercise your dog, as weight gain directly contributes to anal gland buildup.

In addition to this, simply encourage your dog to drink fresh water and monitor your dog’s bowel movements. Their feces can tell you a lot about their overall health and alert you to an issue with their anal glands.

Should I Be Concerned if My Dog’s Butt Smells Like Fish?

greyhound dog
A greyhound standing proud (and tall and skinny)

If your dog’s butt smells like fish, it isn’t immediately a cause for alarm. There are several reasons your dog may be having issues expressing their anal glands, some benign, some more severe. 

While a fishy odor from your dog’s hind end doesn’t immediately point to a problem, it may indicate something more serious that will need to be addressed with your veterinarian. 

Besides natural anal gland buildup, that fishy smell could indicate anal sac disease or, in some instances, an anal sac tumor. 

Anal sac disease is not uncommon in dogs, and vets should be able to identify it quickly. Anal sac disease occurs when an anal sac becomes impacted by a hardening of fluid in the duct, making it difficult for your dog to release the fluid.

While common, the issue will often require antibiotics to remedy, which is why visiting your vet is so important.

In rare cases, the smell could also indicate a tumor in the area, which you will want to have diagnosed as soon as possible. 

Including your vet in your dog’s anal gland issues is essential in determining the severity of the issue and assessing your dog’s needs moving forward. 

What Should I Do if I Notice My Dog’s Butt Smells Like Fish?

two dogs snuggling in bed
Two dogs snuggling in bed.

If you’ve recently noticed that your dog’s butt smells like fish, there are several measures you should take to ensure their health and safety.

When you recognize a fishy odor coming from your dog’s hind end, the most important thing is to consult with your veterinarian. While your dog may simply need their anal glands expressed, it could also be indicative of something more serious, such as anal sac disease

A meeting with your vet the first time you notice the issue is essential to find the underlying cause and develop a game plan. 

If your vet doesn’t believe any underlying issues need to be treated, they will manually express your dog’s anal glands. 

If this is a perpetual issue for your dog, it may be beneficial to have your vet teach you how to express your dog’s anal glands at home for both their comfort and your wallet.

Final Thoughts

A fishy smell emitted from your dog’s hind end is likely caused by a buildup of the fluid produced in their anal glands.

While these glands typically empty themselves when your dog defecates, sometimes they need to be manually expressed; you can learn to do this yourself or get it done by a professional.

While it is normal for some dogs to need their anal glands to be manually expressed occasionally, a fishy odor can indicate a more severe issue such as anal sac disease or anal sac tumors in others.

Talk to your veterinarian to determine whether your dog may be more prone to needing their anal glands expressed or if they believe it’s a more serious problem.