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What Is That Dark Patch On My Dog’s Tail?

That dark patch of fur is actually the result of a gland located on the dog’s or puppy’s tail.

It’s funny how having Lou is bringing back so many memories of when Sherman and Leroy were puppies. 

Some of the things I had forgotten about but Lou is doing a wonderful job of reminding me just how funny, cute, crazy and exhausting Newfie puppies can be at this age. 

Don’t take that as a complaint.

I’m happy to be here for all of it!

One thing that Lou has recently made me remember was the dark brown ring that some young Newfie puppies have on their tail. 

dark brown ring on dog's tail

I say some because I’m not sure if all Newfie puppies have this dark ring.

I clearly remembering Leroy having it but I can’t say that I remember Sherman having it. 

If he did, it wasn’t as noticeable as Leroy’s and Lou’s. 

I also can’t say for sure seen in every Newfie color because I only have browns to compare it to, so if you have a black Newfie puppy that has a dark ring around his tail, let me know and I’ll update this post!

What Is That Dark Patch On Your Dog’s Tail?

That dark patch is actually the result of a gland located on the dog’s tail! 

It’s not an anal gland, but a “violet” or “supracaudal” gland. 

This gland is a secretion gland, meaning that it secretes certain substances.

The area is rich with apocrine and sebaceous glands which causes the color change.

This gland isn’t unique to dogs. 

violet gland on dog's tail

It can also be found in several other animals such as foxes, wolves, some European badgers and even the domestic cat.

In dogs, the tail gland is not as developed as it is in foxes.

Foxes use it for communication purposes and it secretes a strong odor for the purpose of scent marking.

According to veterinarian Dr. Mary Fuller, in dogs, the exact function of this gland remains unknown, but some believe that it may help identify them to other canines. 

Location of the Tail Gland On Dogs

In dogs, the tail gland is an oval area located just above the dog’s 9th caudal vertebrae, but depending on the breed it may be vestigial or entirely absent. 

The presence of the tail gland in dogs is connected with coarse, stiff hairs, and, despite being often called “stud tail,” it can be found in both male and female dogs.

dark spot on puppy's brown tail

Problems With The Tail Gland

While many dogs will not experience any problems with this gland, it can become infected.

This is often called stud tail in dogs and cats. 

Stud tail is caused by the inflammation or infection of the supracaudal gland. 

The gland, in this case, may swell, and there may be hair loss causing a bald, greasy spot at the top area of the tail.

In severe cases, dogs may require a course of antibiotics.

In some dogs, tumors may also develop in this area so it’s always important to see your vet if you suspect any problems. 

In my personal experience, none of my dogs have ever had any issues with their tail gland.

The older they get, the more the dark ring seems to fade and I forget about it.

So there you go! That’s what that dark ring is on your puppy’s tail!

Fact check: I verified this information with my vet at Lou’s puppy appointment yesterday!


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Monday 6th of September 2021

All of our Boys have had them, 1 brown and 2 black. I always thought it was their Big Boys coats coming in. ??‍♀️??‍♀️

Bryson Fico

Tuesday 31st of August 2021

We always wonder about the dark spot on Zoey's tail, but we never bothered to dig deeper since it wasn't causing her any problems. Thank you for the insight.


Monday 30th of August 2021

Thanks for sharing, we’ve seen this in both our Newfies. We have a brown female who had this as a pup and just recently got a black male. We were just talking about this spot the other day and wondered what/why this area was different. Love site!


Wednesday 28th of July 2021

Yup I remember seeing that on my guy when he was younger


Saturday 17th of July 2021

We have a black girl who we got as a puppy, and she had this! Her puppy goat was fluffy and charcoal colored, but the spot on her gland was a darker black.

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