Check the Rear: Anal Adenoma in Dogs

These tumors occur most often in older male dogs who are not neutered.

If you have a hairy dog, make sure to ask the groomer for a “hygiene clip.” By: Lindasay

Ever noticed how things come in 3s?

This is something I’ve remarked on recently, but it happened again during today’s consultations. This time there were 3 dogs each with a pain in the butt — or, more precisely, bleeding from the anal area.

OK, to be totally honest, these dogs weren’t identical cases (2 had anal tumors, while the other had an infected anal gland). But it did occur to me that anal tumors in dogs are a subject not much talked about but relatively common in male dogs.


Gus the German Shepherd

Gus is a large, hairy German Shepherd. Indeed, Gus is the sort of dog who commands respect with his sheer bulk and ability to do harm, should he chose to. Luckily for me, Gus is a chill character; he’d more likely inflict pain by treading on your foot than anything else.

His appointment was to recheck a lump on his bottom. The week before, his human had noticed him bothering at his rear and leaving spots of blood on the floor where he sat.

Due to the dog’s impressively fluffy trousers, it had taken clippers and damp cotton wool to get the fur under control enough for a good look. The problem was a cherry-sized lump sitting at the “12 o’clock” position on his anal ring. Somehow the lump had become ulcerated, and it was the raw surface that was bleeding.

Gus had been prescribed a course of antibiotics, and his human was bathing the lump in saltwater twice a day. Indeed, at today’s follow-up, Gus was much more comfortable, and the lump had stopped bleeding.

I chatted to his human about the options for treatment going forward. We decided to take a cautious approach and wait to see if the issue recurs, and if it does, then surgical removal is the next option.

Problems Related to the Rear End

We’ll find out more about anal lumps in a moment, but first, let’s take a look at what else might cause symptoms, such as licking the rear end and bleeding from the bottom.

The main problems uppermost in my mind are:

  • Anal sac abscess: This common problem means the anal sacs become infected and form an abscess that bursts.
  • Anal furunculosis: This unpleasant condition occurs when the tissue around the anus simply melts away, leaving deep sores and tracts that are extremely painful for the dog.
  • Anal adenoma: This is the most common type of cancer affecting the anus. Mainly found in male dogs, the male hormone testosterone stimulates their growth.
It’s very important to protect animals from infection after surgery. By: Aldras

Anal Tumors

The most common tumor affecting the anal ring is the “anal adenoma.” This is a benign cancer, meaning it’s not aggressive and rarely spreads. However, anal adenomas can still cause problems if they grow large.

While some anal adenomas are small, grow slowly and rarely cause a problem, this isn’t always the case. Some grow quite large, break open and ulcerate, with the risk of infection because of where they are. Unfortunately, some of these ulcerated lumps can also bleed, sometimes quite a lot, which makes surgical removal necessary.

Why Anal Adenomas Occur in Male Dog

Anal adenomas are a problem of elderly, entire (unneutered) male dogs. This is because they are fed by the male hormone testosterone. Over a lifetime of being soaked in testosterone, sometimes the tissue of the anal ring forms tumors — it’s just the way it is.

This makes Gus’ case intriguing because he is neutered. However, it transpired he’s a rescue dog, adopted by the person in the previous year. As part of the terms of adoption, he’d been neutered (even though he was elderly) much later in life than is usual.

His age and history made Gus a candidate for anal adenoma formation. But there’s also a chance that now he’s neutered and his testosterone levels are lower, his lump may stop growing. Indeed, part of me wonders if he’d hidden the lump for a while — he is extremely hairy around the rear.


The main treatment is surgical removal. Once formed, these tumors are unlikely to shrink down, and there’s always a risk of continued growth in intact male dogs. This means at the same surgery it’s wise to neuter the dog to prevent new adenomas from forming.

In elderly, frail patients for whom an anesthetic isn’t advisable, we can try to reduce future growth through medical treatment and the use of hormone implants to reduce testosterone levels. Sometimes this works; sometimes it doesn’t.

As well as the anesthetic risk, there’s also a chance of complications because of where the lumps grow. Obviously, the anus is not a sterile place, and there’s a risk of the operation site becoming contaminated with feces post-operatively. To reduce the risk of infection, the dedicated human syringes saltwater over their dog’s bottom after each bowel movement.

In addition, there’s a theoretical risk of fecal incontinence following surgery. This is because the lumps grow on the anal ring, and during the operation there’s a small chance of nerve damage to the area.

In short, if you have a male dog, then desexing at a younger age can protect him from anal adenoma. If yours is an older, intact male dog, then be vigilant for lumps and bumps around the rear and get them checked by a vet. Oh, and if your dog is super hairy, it’s a good idea to ask for a hygiene clip so you can keep an eye on what’s going on.

As for Gus, only time will tell if his lump continues to grow and be troublesome. But fortunately, his new person is devoted and will act immediately should the need arise.



This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed Feb. 9, 2018.


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