Anal Gland Cancer in Dogs (Anal Sac Adenocarcinoma)

Key Points

• Between 20% and 57% of dogs have no symptoms when the tumor is found, usually by a vet's gloved finger during a rectal exam (Cino & Martano, 2024).
• Spread to nearby lymph nodes is common at diagnosis, reported in 23.4% to 83% of dogs (Cino & Martano, 2024). Even tumors under 2 cm had already spread to lymph nodes in 20% of dogs in one study (Jones & Wustefeld-Janssens, 2023).
• Between 16% and 53% of dogs have high blood calcium caused by a hormone-like substance the tumor makes (Cino & Martano, 2024). Excessive thirst and urination can be the first clue.
• English Cocker Spaniels are strongly overrepresented among dogs with anal gland cancer (Cino & Martano, 2024).
• Staging decides almost everything. Median survival ranged from 40 months for stage 1 down to under 3 months for stage 4 in the study behind the staging system (Polton & Brearley, 2007, as cited in Cino & Martano, 2024).
• There's no known way to prevent it. Routine rectal exams, at least yearly and twice a year in older dogs, are the best way to catch it early (Cornell University College of Veterinary Medicine, n.d.).
• Surgery removes the tumor and, when needed, affected lymph nodes. Radiation and toceranib also have evidence behind them, while chemotherapy results are mixed (Cino & Martano, 2024; Heaton et al., 2020).

Detailed Explanation

What are the anal glands, and what is anal gland cancer?

Dogs have two small sacs under the skin, one on each side of the anus. Their lining makes a strong, unpleasant-smelling discharge that varies in color and thickness, and it leaves through a tiny opening near the anus. Normally it gets squeezed out when a dog poops. A nervous or excited dog can release it too, which is part of why it's thought to work as a territorial scent marker (Cornell University College of Veterinary Medicine, n.d.).

The glands lining those sacs are apocrine glands. When their cells turn cancerous, you get an apocrine gland anal sac adenocarcinoma, which most owners know as anal gland cancer. It's the most common cancer of the anal sacs and makes up about 2% of skin tumors in dogs (Cornell University College of Veterinary Medicine, n.d.). That 2% figure traces back to an older study, though, and no recent work has confirmed it (Cino & Martano, 2024).

Anal sacs also get plenty of benign problems: impaction, inflammation (sacculitis), and abscesses (Cornell University College of Veterinary Medicine, n.d.). Those are common and usually minor, and they aren't cancer. It also isn't the same as a perianal adenoma, a benign tumor of different glands around the anus. And it isn't intestinal cancer, even though it sits right next to the rectum. If you've seen the word "adenocarcinoma" on a report, our anal gland cancer overview page and our guide to lumps that aren't cancer can help you sort out which is which.

Which dogs get anal gland cancer?

Most dogs are 9 to 11 years old at diagnosis, though cases have been reported from 5 to 15 (Cino & Martano, 2024). Cornell's Riney Canine Health Center puts the average at about 10 (Cornell University College of Veterinary Medicine, n.d.). Early reports suggested females were affected far more often. More recent studies haven't found any real difference between the sexes (Cino & Martano, 2024).

Breed matters, and one stands out. Our article on the biggest risk factors for dog cancer covers the broader picture. English Cocker Spaniels carry about 7.3 times the odds of other dogs (Cino & Martano, 2024). A British study linked the disease in that breed to a particular immune gene variant, DLA-DQB1*00701, found in 95% of affected Cocker Spaniels compared with 73% of unaffected ones (Aguirre-Hernández et al., 2010). That's a genetic association, not a test that can predict which dog will get cancer. British studies have also flagged Springer Spaniels and Cavalier King Charles Spaniels as higher risk (Cino & Martano, 2024). Cornell's list of commonly affected breeds is broader still: Alaskan Malamutes, Cavalier King Charles Spaniels, Dachshunds, English Cocker Spaniels, English Springer Spaniels, German Shepherds, and Golden Retrievers (Cornell University College of Veterinary Medicine, n.d.).

If you share your home with an English Cocker, regular rectal exams at checkups make a lot of sense. Ask for one.

What are the signs of anal gland cancer in dogs?

Many dogs with anal gland cancer show nothing at all. That's why so many of these tumors are found by accident, and why the authors of a 2024 review recommend rectal palpation for every dog (Cino & Martano, 2024). Our 10-minute dog cancer check covers what you can watch for at home, but a rectal exam is a vet's job.

When signs do appear, they come from three places.

An anal gland tumor can cause swelling beside the anus, bleeding, licking or biting at the area, itching, or scooting (Cino & Martano, 2024). It's easy to blame anal gland trouble. Recurring "anal gland problems" in an older dog deserve a closer look.

Enlarged lymph nodes inside the pelvis can press on the rectum and urethra. That shows up as straining to poop, which happens in 14% to 34% of dogs, along with painful defecation or straining to urinate (Cino & Martano, 2024).

High calcium causes the third set of signs. These tumors can make a substance called parathyroid hormone-related protein (PTHrP), which acts like the body's own calcium-raising hormone (Cino & Martano, 2024). The result is increased thirst and urination in some dogs. Not every dog with high calcium shows it, though. In the largest older study, 27% of 113 dogs had high calcium, but only 22% had increased thirst and urination (Williams et al., 2003, as cited in Cino & Martano, 2024). A routine blood panel can catch it before you see a thing.

Other signs are vaguer. Dogs may be lethargic, constipated, off their food, or vomiting. Some develop weakness or swelling in the hind legs (Cornell University College of Veterinary Medicine, n.d.).

How is anal gland cancer diagnosed?

It usually starts with that rectal exam, when a vet finds a mass in the area of one or both anal sacs. During the same exam, your vet will feel for enlarged lymph nodes inside the pelvis. Not every dog has them, and in bigger dogs they may sit too far in to reach (Cornell University College of Veterinary Medicine, n.d.).

A fine needle aspirate can show cells consistent with this tumor. A biopsy is still needed to confirm it, either a piece of the mass or the whole thing once it's removed (Cornell University College of Veterinary Medicine, n.d.). Our article on reading your dog's biopsy report explains the terms you'll see.

Bloodwork matters more here than with many cancers, because a chemistry panel is how high calcium gets caught. Blood and urine tests are often normal. When they aren't, the usual findings are high calcium or signs of kidney disease (Cornell University College of Veterinary Medicine, n.d.). A complete blood count rounds out the picture.

How is it staged, and has it spread?

Staging is the step owners most often underestimate, and it's the one that changes the plan the most. These tumors spread first to the lymph nodes deep inside the pelvis and along the spine, called the iliosacral or sublumbar nodes. You can't feel them from the outside. Our article on where a dog's lymph nodes are shows why.

How often does it spread? Cornell puts lung spread at about 2% to 13% of dogs and enlarged sublumbar lymph nodes at about 50%, with a smaller share of dogs showing spread to other abdominal organs (Cornell University College of Veterinary Medicine, n.d.). Studies vary widely, as you'd expect from small groups of dogs.

Small tumors are not automatically safe. In a study of 116 dogs, 20% of dogs with tumors under 2 cm already had lymph node spread, compared with 63% of dogs with larger tumors (Jones & Wustefeld-Janssens, 2023). Some dogs with no spread at first developed it later, a median of 179 days afterward for small tumors and 205 days for larger ones (Jones & Wustefeld-Janssens, 2023). The authors' message was plain: image the abdomen no matter how small the tumor looks.

Abdominal ultrasound is the usual first look. CT tends to find more of the nodes, though. In one small study of 12 dogs, CT identified 61 iliosacral lymph nodes while ultrasound found 30, and ultrasound didn't see any of the sacral nodes CT picked up (Cino & Martano, 2024). Ultrasound did flag a few abnormal nodes that looked normal on CT, so neither test is perfect. CT is generally preferred where it's available, and some hospitals also offer MRI (Cornell University College of Veterinary Medicine, n.d.). Chest X-rays or CT check the lungs.

All of that feeds into the staging system most oncologists use, developed by Polton and Brearley (2007, as cited in Cino & Martano, 2024):

Those are medians from one group of dogs, and half lived longer. Treatment has moved on since, too. Stage 4 dogs not given toceranib have had median survival of 71 to 82 days, but in one study of 15 stage 4 dogs treated with it, median survival was 356 days (Cino & Martano, 2024). Our article on cancer staging in dogs explains how staging works in general.

Surgery for Anal Gland Cancer

Removing the affected anal sac, called an anal sacculectomy, is the main treatment for most dogs with anal gland cancer. The closed technique, where the sac is removed intact without being opened, is preferred (Cino & Martano, 2024). The tumor sits next to the anal sphincter and rectum, so it's delicate work, and getting a larger mass out completely can be hard (Cornell University College of Veterinary Medicine, n.d.).

Complications after surgery happen in roughly 7% to 21.8% of dogs. They include infection, the incision opening up, and fecal incontinence, which occurs in 2.1% to 7% of dogs (Cino & Martano, 2024). Incontinence is usually temporary but can be permanent, and poor wound healing and narrowing of the anus (anal stricture) can also happen (Cornell University College of Veterinary Medicine, n.d.). Ask your surgeon about their own complication rate and how often they do this operation. Our article on recovery after cancer surgery covers what home care looks like.

The tumor can come back where it was removed. Local recurrence has been reported in 13% to 44% of dogs (Cino & Martano, 2024), and Cornell cites up to 45% (Cornell University College of Veterinary Medicine, n.d.). Getting clean margins helps. In a 2026 study of 74 dogs, complete margins were achievable in most dogs and lowered the risk of local recurrence (Gordon et al., 2026). Our article on what clear margins mean explains why "clean" doesn't always mean "cured."

The cancer can also show up in the other anal sac. Between 4% and 20% of dogs have both sacs involved, and in one series of four dogs, the second tumor appeared 50 to 390 days after the first was removed (Cino & Martano, 2024). Rechecks should include the remaining sac.

Should the lymph nodes be removed?

When the lymph nodes are enlarged, surgeons can often remove them through a separate incision in the abdominal wall. This is bigger surgery. Serious bleeding is a risk, and so is nerve damage that can leave a dog temporarily or permanently unable to control urination (Cornell University College of Veterinary Medicine, n.d.). Cornell puts the overall complication rate at about 10% (Cornell University College of Veterinary Medicine, n.d.).

Individual studies have reported higher numbers. In one study of iliosacral lymph node removal, 15.7% of dogs had complications during the operation and 10.4% afterward, with bleeding a particular risk when nodes were larger than 4.5 cm (Cino & Martano, 2024). Doing the anal sac and the lymph nodes under the same anesthetic carried a higher complication rate in two studies, 42% compared with 5% when they were done separately (Cino & Martano, 2024).

Node spread does raise the stakes. In a study of 42 dogs, those with lymph node spread at surgery faced 2.5 times the risk of progression and 2.31 times the risk of dying from the tumor compared with dogs without it (Potanas et al., 2015, as cited in Cino & Martano, 2024). Removing those nodes appears to help, and dogs with enlarged nodes have improved survival when the nodes come out too (Cornell University College of Veterinary Medicine, n.d.). Surgery can also buy time when the disease comes back. In one report, a second operation for recurrent disease added a median of 283 days (Cino & Martano, 2024). Spread to the nodes is serious. It isn't the end of the road.

Radiation Therapy

Radiation therapy has some of the longest reported survival times for this cancer, with medians of 22 to 32 months across studies (Cino & Martano, 2024). It can improve both clinical signs and survival time (Cornell University College of Veterinary Medicine, n.d.). It can be given before, during, or after surgery, aimed at the anal sac and the lymph nodes, to lower the risk of recurrence when the tumor can't be removed completely. It's also used to ease signs when surgery isn't an option (Cornell University College of Veterinary Medicine, n.d.).

In one early study of 15 dogs treated with surgery, radiation, and the chemotherapy drug mitoxantrone, median survival was 956 days, though every dog had short-term side effects (Turek et al., 2003, as cited in Cino & Martano, 2024). For dogs with stage 3 disease, adding radiation lengthened the time before the cancer progressed: 347 days with radiation versus 159 days with surgery alone (Meier et al., 2017, as cited in Cino & Martano, 2024). Newer, more targeted approaches like stereotactic radiation are also being studied, with a median survival of 991 days in a pilot study (Cino & Martano, 2024).

The pelvis is a sensitive area to irradiate. Side effects are common, with reported toxicity rates from 33% to 100% depending on the protocol (Cino & Martano, 2024), and some complications can be life-threatening (Cornell University College of Veterinary Medicine, n.d.). Our article on quality of life after radiation goes into what to expect.

Does Palladia (toceranib) help?

Toceranib is an oral targeted drug, and AGASACA is one of the tumors where it seems to help. In a retrospective study of 36 dogs, about 69% had some clinical benefit, median progression-free survival was 313 days, and median overall survival was 827 days (Heaton et al., 2020). Dogs that responded lived significantly longer, and high calcium was linked to a worse outcome (Heaton et al., 2020). The authors called for prospective trials to compare it properly with other treatments.

Like any cancer drug, it has side effects and needs regular monitoring. Our article on Palladia side effects covers them.

Does chemotherapy help?

The case for traditional chemotherapy here is weaker than many families expect. In the 113-dog study, dogs treated with chemotherapy alone had a median survival of 212 days, the shortest of any treatment group (Williams et al., 2003, as cited in Cino & Martano, 2024). One later study found that platinum chemotherapy after surgery was actually associated with a higher risk of progression (Pradel et al., 2018, as cited in Cino & Martano, 2024), while another found somewhat longer survival with carboplatin but no difference in the time before the cancer progressed (Cino & Martano, 2024).

The honest summary: chemotherapy hasn't been proven to improve survival, but it may offer some benefit, especially combined with radiation (Cornell University College of Veterinary Medicine, n.d.). For dogs who don't have surgery, chemotherapy, radiation, or both may help (Cornell University College of Veterinary Medicine, n.d.). That decision deserves a careful conversation with a veterinary oncologist. If your regular vet is managing the case, it's fair to ask for a referral.

Treating High Calcium

High calcium is dangerous in its own right, so your vet may need to stabilize your dog first, usually with IV fluids and medications such as corticosteroids or diuretics (Cornell University College of Veterinary Medicine, n.d.). Because the tumor is what makes the PTHrP driving it (Cino & Martano, 2024), dealing with the tumor is the long-term fix. Ask what your dog's calcium level is now and how the team plans to handle it.

How long can a dog live with anal gland cancer?

It depends mostly on stage and treatment, and the range is wide. In the study behind the staging system, median survival ran from 40 months for small tumors with no spread down to under 3 months once cancer reached distant organs (Polton & Brearley, 2007, as cited in Cino & Martano, 2024). With surgery, some dogs average more than three years (Cornell University College of Veterinary Medicine, n.d.).

Treatment makes a real difference at every stage. Across recent studies, dogs treated with surgery plus other therapy had median survival of 15 to 28 months, compared with 6.9 to 8.7 months for chemotherapy alone (Cino & Martano, 2024). Radiation has some of the longest reported survival times, with medians of 22 to 32 months (Cino & Martano, 2024). Even at stage 4, dogs not given toceranib have had median survival of 71 to 82 days, while one group treated with it reached 356 days (Cino & Martano, 2024).

A median is the halfway point, so half of dogs live longer. Your dog's stage, calcium level, and pathology report will tell you far more than any single number. Our articles on how long dogs live with cancer and prognosis by cancer type put these figures in context.

Is anal gland cancer painful?

It can be, though many dogs show no signs at all when it's found (Cino & Martano, 2024). Discomfort usually comes later, from a growing tumor or from enlarged lymph nodes pressing on the rectum, which can make pooping difficult or painful (Cino & Martano, 2024). Licking, biting at the area, and scooting can also point to irritation (Cino & Martano, 2024). Dogs are good at hiding pain, so our guide to signs a dog is hiding pain is a useful companion. Pain relief is a standard part of care, both after surgery and in palliative care (Cornell University College of Veterinary Medicine, n.d.).

What affects the prognosis?

Several things push a dog's prognosis up or down: tumor size, spread to lymph nodes or distant organs, and the treatment chosen (Cornell University College of Veterinary Medicine, n.d.).

Stage comes first, as the table shows. Tumor size matters on its own too. Tumors under 2.5 cm carry a better prognosis (Cornell University College of Veterinary Medicine, n.d.). In the 113-dog study, dogs with smaller tumors (under 10 cm²) had a median survival of 584 days, compared with 292 days for larger ones (Williams et al., 2003, as cited in Cino & Martano, 2024).

Lymph node spread and distant spread both shorten survival. Our article on metastatic cancer in dogs explains what spread means for treatment. Distant spread is the bigger blow, with reported medians of 71 to 356 days (Cino & Martano, 2024).

High calcium is more controversial than it sounds. Cornell lists it as a sign of shorter average survival (Cornell University College of Veterinary Medicine, n.d.), but the research is split: some studies tie it to shorter survival, others don't (Cino & Martano, 2024; Jones & Wustefeld-Janssens, 2023). In the 2026 study, dogs with high calcium before surgery had a median survival of 7.5 months (Gordon et al., 2026).

The pathology report adds information. Tumor cells invading blood or lymph vessels was linked to shorter survival, 21 months in the 2026 study (Gordon et al., 2026), and a solid growth pattern under the microscope has also been tied to worse outcomes (Pradel et al., 2018, as cited in Cino & Martano, 2024).

How the dog presents matters as well. Dogs found incidentally, with no symptoms, did far better than dogs with signs throughout the body (Pradel et al., 2018, as cited in Cino & Martano, 2024). That's one more argument for routine rectal exams.

Can anal gland cancer be prevented?

Not really. Removing healthy anal sacs to head off cancer isn't recommended, because the surgery has its own complications, and there's no other known way to prevent it (Cornell University College of Veterinary Medicine, n.d.). What helps is catching it early. Cornell recommends a rectal exam at least once a year, and twice a year for older dogs, which fits well with routine cancer screening for dogs (Cornell University College of Veterinary Medicine, n.d.).

What happens after treatment?

Expect regular rechecks. They usually include a rectal exam that checks both sides, a calcium level, and repeat abdominal imaging to watch the lymph nodes. Ask how often your team wants to see your dog, and what should bring you in sooner. Our article on whether cancer can come back explains recurrence and spread.

Tracking thirst, urination, appetite, and how your dog is pooping between visits gives your vet something concrete to work with. The Dog Cancer Tracker makes that easier.

If surgery isn't possible, or isn't the right choice for your dog, palliative care focuses on comfort. It can include pain relief with nonsteroidal anti-inflammatories (NSAIDs) or corticosteroids, though not both together, plus fluid therapy and diuretics (Cornell University College of Veterinary Medicine, n.d.). See our guide to pain management for dogs with cancer.

When treatment stops working, or isn't an option, the focus shifts to keeping your dog comfortable for as long as possible. Choosing not to treat is a legitimate decision too. A quality of life scale can help you track good and bad days, hospice care at home can support the final stretch, and our article on when to euthanize a dog with cancer walks through that decision.

A diagnosis like this is a lot to take in. Ask every question, including about money; our article on the cost of treating cancer in dogs can help you plan. And look after yourself, too. Our piece on self-care for dog cancer caregivers is written for you.

Thinking About Quality of Life

The quality-of-life issues here are specific: comfort while defecating, and how high calcium makes a dog feel.

Both are treatable, which makes them worth raising promptly rather than accepting. A dog straining painfully to defecate, or one drinking constantly and feeling nauseated from high calcium, can often be made considerably more comfortable.

Track your dog weekly across a few consistent dimensions — comfort, appetite, energy, ease of defecating, thirst, engagement with the family, and whether good days still outnumber bad. Written notes over months are more reliable than memory.

Ask your veterinary team what the likely course looks like and what to expect if defecation becomes obstructed, so that decision can be considered in advance rather than in a crisis.

Common Questions

My dog has been scooting. Should I be worried? Usually it is ordinary anal gland trouble, which is common and benign. But scooting that persists, or begins in an older dog with no history of it, is a reason to ask for a rectal examination. That examination takes seconds and is how many of these tumors are found.

Why is my dog drinking so much? Anal sac adenocarcinoma frequently produces a substance that raises blood calcium, which causes marked thirst and urination. It is treatable, and removing the tumor usually normalizes it, but sustained high calcium damages the kidneys — so it warrants prompt attention.

Can anal gland cancer be eliminated for good? It is generally controlled rather than eliminated. Local recurrence is common. That said, with surgery and appropriate additional treatment, many dogs have a good year or more, and dogs with small tumors, clear lymph nodes, and normal calcium can do considerably better.

Will my dog be incontinent after surgery? Some temporary reduction in control is common in the first days. Permanent incontinence is uncommon when the surgery is performed by an experienced surgeon, and it is a fair question to ask about how often yours does this procedure.

Do the lymph nodes really need to come out? Where they are involved, removing them relieves pressure on the rectum and is associated with longer survival. It is a more demanding operation, so discuss with your surgeon whether it is appropriate for your dog.

My dog has a lump near the anus but is neutered and female. What could it be? Not the common benign perianal adenoma, which occurs almost exclusively in unneutered males. Any perianal mass in a female or neutered dog should be examined and biopsied rather than assumed benign.

How would this be caught earlier? By rectal examination, which is why it is worth including in senior wellness checks and worth requesting if your dog is scooting, straining, or drinking more than usual. Many of these tumors are found this way before any signs appear.

The Research

EMMS, S.G. (2005) “Anal sac tumours of the dog and their response to cytoreductive surgery and chemotherapy,” Australian Veterinary Journal, 83(6), pp. 340–343. 

Kessler, M. (2014) Perianal tumors – WSAVA 2014 Congress – Vin, Powered By VIN. The World Small Animal Veterinary Association World Congress Proceedings, 2014. Available at: https://www.vin.com/apputil/content/defaultadv1.aspx?pId=12886&id=7054772 (Accessed: December 11, 2022).

Klingemann, H. (2018) “Immunotherapy for dogs: Running behind humans,” Frontiers in Immunology, 9. Available at: 

Mehler, S.J. and Clifford, C.A. (2019) Anal sac anal gland adenocarcinoma — how combination therapy impacts outcome, IVC Journal. Innovative Veterinary Care. Available at: https://ivcjournal.com/anal-sac-anal-gland-adenocarcinoma/#:~:text=Tumors%20of%20the%20anal%20sac%20are%20uncommon%20and,for%2015%25%20to%2020%25%20of%20all%20perianal%20tumors. (Accessed: December 11, 2022).

Morello, E.M. et al. (2021) “Prognostic value of ki67 and other clinical and histopathological factors in canine apocrine gland anal sac adenocarcinoma,” Animals, 11(6), p. 1649. 

Olsen, A. (2020) Anal sac adenocarcinoma – dallas veterinary surgical center, DVSC. Available at: https://dvsc.com/medical_library/anal-sac-adenocarcinoma/ (Accessed: December 11, 2022).

Williams, L.E. et al. (2003) “Carcinoma of the apocrine glands of the anal sac in dogs: 113 cases (1985–1995),” Journal of the American Veterinary Medical Association, 223(6), pp. 825–831. 

References

Aguirre-Hernández, J., Polton, G., Kennedy, L. J., & Sargan, D. R. (2010). Association between anal sac gland carcinoma and dog leukocyte antigen-DQB1 in the English Cocker Spaniel. Tissue Antigens, 76, 476-481. 

Cino, M., & Martano, M. (2024). Is there anything new in canine AGASACA? Veterinary Sciences, 11(12), Article 629. 

Cornell University College of Veterinary Medicine. (n.d.). Anal sac adenocarcinoma. Richard P. Riney Canine Health Center. https://www.vet.cornell.edu/departments/riney-canine-health-center/canine-health-information/anal-sac-adenocarcinoma

Gordon. (2026). Investigation of the "R" tumor margin classification and prognostic factors in apocrine gland anal sac adenocarcinoma of dogs. Veterinary Surgery. 

Heaton, C. M., Fernandes, A. F. A., Jark, P. C., & Pan, X. (2020). Evaluation of toceranib for treatment of apocrine gland anal sac adenocarcinoma in dogs. Journal of Veterinary Internal Medicine, 34(2), 873-881.

Jones, A. E., & Wustefeld-Janssens, B. G. (2023). Veterinary and Comparative Oncology, 21(2), 327-331. 

Meier, V., Polton, G., Cancedda, S. (2017). Outcome in dogs with advanced (stage 3b) anal sac gland carcinoma treated with surgery or hypofractionated radiation therapy. Veterinary and Comparative Oncology, 15, 1073-1086.

Polton, G. A., & Brearley, M. J. (2007). Clinical stage, therapy, and prognosis in canine anal sac gland carcinoma. Journal of Veterinary Internal Medicine, 21(2), 274-280. 

Potanas, C. P., Padgett, S., & Gamblin, R. M. (2015). Surgical excision of anal sac apocrine gland adenocarcinomas with and without adjuvant chemotherapy in dogs: 42 cases (2005-2011). Journal of the American Veterinary Medical Association, 246, 877-884. 

Pradel, J., Berlato, D., Dobromylskyj, M., [REMAINING AUTHORS TO CONFIRM]. (2018). Prognostic significance of histopathology in canine anal sac gland adenocarcinomas: Preliminary results in a retrospective study of 39 cases. Veterinary and Comparative Oncology, 16, 518-528. 

Turek, M. M., Forrest, L. J., Adams, W. M. (2003). Postoperative radiotherapy and mitoxantrone for anal sac adenocarcinoma in the dog: 15 cases (1991-2001). Veterinary and Comparative Oncology, 1, 94-104. 

Williams, L. E., Gliatto, J. M., Dodge, R. K. (2003). Carcinoma of the apocrine glands of the anal sac in dogs: 113 cases (1985-1995). Journal of the American Veterinary Medical Association, 223

This page is for education and does not replace advice from your own veterinarian, who knows your dog. Increased thirst and urination alongside an anal mass warrants prompt veterinary attention.