What is Perianal Tumor?
The perianal area contains sebaceous-like structures in the perianal skin of dogs, located close to the anus. Perianal tumors originate from these tissues, and most commonly develop in intact, older male dogs. While benign tumors are generally harmless and can be easily treated, the malignant variety can create life-threatening conditions for your dog, and will need to be treated aggressively.
Perianal tumors develop close to, or directly on, the anus in dogs, and originate from the perianal tissues. These tumors can be single or multiple nodules in the skin that can be benign or malignant, and can cause signs that involve elimination. If hypercalcemia is also present, your dog can also suffer from kidney issues that can lead to failure.
Symptoms of Perianal Tumor in Dogs
The presence of a perianal tumor is often not painful for your dog, but it can cause your dog to pay more attention to the area. Some of these tumors grow slowly for months or years, and they can eventually rupture and bleed, leaving your dog susceptible to infections. Tumors may appear as single or multiple masses in the anal area, and can create a thickened ring around the anus. Signs include:
- Round, nodules in the skin near anus
- Thickened ring of tissue surrounding anus
- Bleeding nodules
- Excessive licking of the anal area
- Scooting rear end on ground
- Colorectal obstruction
- Rectal pain
- Protruding rectal mucous membrane
- Straining to defecate
- Bloody feces
- Vomiting blood
- Increased thirst
- Increased urination
- Decreased appetite
- Lethargy
- Reduced exercise tolerance
- Growth on the testes
- Hypercalcemia, or elevated blood calcium levels
Types
- Perianal tumors are categorized as either benign adenomas or malignant carcinomas
- Benign adenomas are masses of the perianal area that are not classified as cancerous, but that may spread, regardless.
Malignant carcinomas, or adenocarcinomas, are also masses of the perianal area. These are uncommon cancerous masses that are hard to distinguish from benign adenomas, but can spread to other locations in the body and cause hypercalcemia, or increased blood calcium levels that can lead to kidney failure. Malignant carcinomas require more intensive diagnostic testing and treatments, therefore it is necessary to determine if your dog’s tumors are malignant.
Causes of Perianal Tumor in Dogs
While the definitive cause of perianal tumors is still unknown, testosterone is believed to influence cell proliferation in the glands. Intact male dogs have an increased risk compared to females in developing these tumors. For females, adrenocortical hormones may play an important role in tumor growth.
Additionally, genetic factors may also influence the possible progression of this type of tumor. Breeds who seem to be at a higher risk include:
- Beagles
- Cocker Spaniels
- English Bulldogs
- Samoyed breeds
Diagnosis of Perianal Tumor in Dogs
A physical exam can help your veterinarian determine if the masses or nodules on your dog’s anal area may be tumors. Often a urinalysis is performed, as well as blood work that can reveal an elevated blood calcium level, a sign of these types of growths.
Many perianal tumors will be benign, but a small percentage of these growths can be malignant. A tissue sample by a fine-needle aspirate or by a surgical biopsy will be examined under the microscope to determine what kind of tumor your dog has. Chest and abdominal X-rays and ultrasounds can also help to determine of the tumors have spread, such as to the lymph nodes or prostate gland.
Treatment of Perianal Tumor in Dogs
Treatment for these tumors can vary, and can be more difficult if they have spread. Treatment for tumors that are diagnosed as malignant aims to improve your dog’s quality of life, while benign masses can be completely resolved.
For intact, male dogs, the primary treatment is the removal of both testes. This eliminates much of the testosterone, which can result in regression of small and benign tumors. Your dog is monitored after castration to assess if further removal is necessary.
In both male and female dogs, small tumors can also be removed with cryotherapy, which freezes off the masses. For larger or malignant tumors, surgical removal may be necessary. Fecal incontinence can result from surgery due to damage to the sphincter muscle.
Chemotherapy and radiation therapy may also be prescribed in addition to castration, and are generally given over several weeks. Estrogen therapy can be administered to shrink tumors, and is used especially in cases where castration is not an option in male dogs. A side effect of estrogen therapy is a life threatening condition of bone marrow suppression.
Supportive treatments can include soothing creams for irritated anal skin, and medications to reduce blood calcium levels, improve kidney function, and alleviate pain and nausea.
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Recovery of Perianal Tumor in Dogs
For benign perianal tumors, recovery is very good. Neutering leads to a complete regression in the majority of these cases. Your dog may need post-operative care, and should be seen by your veterinarian in 1 to 3 months to monitor tumor regression. In a small percentage of cases, tumors may recur, but can be treated.
If your dog has a malignant tumor, post-operative care may be longer and more intense. You may need to monitor your dog for complications, such as infections and fecal incontinence. Your dog may need frequent veterinary visits for treatments. Recovery is poor, as many dogs can die from the effects of the tumors within a year from diagnosis, or are euthanized.
Perianal Tumor Questions and Advice from Veterinary Professionals
Miniature Australian Shepherd
Ten Years
33 found this helpful
33 found this helpful
My pet has the following symptoms:
Adenoma
Small anal adenoma. Vet says does not extend internally and likely not malignant. No needle aspiration has been done. One vet squeezed it a couple of months ago and got a lot of “white gunk” out of it. She thought it would then dry up and fall off. Would you surgically remove. Not bothering my fur baby
May 1, 2021
Answered by Dr. Linda S. MVB MRCVS
33 Recommendations
Without an aspirate or biopsy we cannot say that this is an adenoma, though it may be suspected.
While it may well be benign, I would advise sampling it to ensure this is truly the case.
If it turns out to be benign, we may consider not removing it.
May 1, 2021
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cho
Ten Years
42 found this helpful
42 found this helpful
My pet has the following symptoms:
My dog has a big mass above tail going towards Anas amd spin and it's hard and she keeps licking and biting it
Jan. 14, 2021
Answered by Dr. Maureen M. DVM
42 Recommendations
Hi,
There are many types of body swellings. The mass can be an abscess(accumulation of pus), hematoma(blood), seroma(serum), lipoma(fat), or a tumor.
Visiting your vet may be the best thing to do for proper diagnosis and treatment.
Good luck
Jan. 14, 2021
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Norfolk Terrier
Twelve Years
20 found this helpful
20 found this helpful
My pet has the following symptoms:
Hello,
My dog has had a small lump underneath his anus for about a year now. It has only grown slightly, recently. About the size of a dime. It does not bother him and he does not scoot or anything. I am concerned though, that it may grow larger and pop.
Jan. 3, 2021
Answered by Dr. Sara O. DVM
20 Recommendations
Hello if it is growing it is best to have it removed.
Jan. 3, 2021
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Miniature Schnauzer
Eight Years
20 found this helpful
20 found this helpful
My pet has the following symptoms:
Redness
right next to her anal there is a red bump that is kind of large and she has had some of her poop spill out is there a way to treat this at home
Dec. 11, 2020
Answered by Dr. Linda S. MVB MRCVS
20 Recommendations
Thank you for this photo.
This is a large swelling.
This may be a hernia, tumour, large abscess or something else.
She does need to be seen by a vet and may need some imaging such as an xray or ultrasound.
Treatment will then depend on what we find.
Dec. 11, 2020
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Heeler mix
Seventeen Years
32 found this helpful
32 found this helpful
My pet has the following symptoms:
Fatty Tumor On Her Butt
My dog has had this fatty tumor about 10 years. It finally grew large enough to split and bleed. It’s about the size of a normal egg. The main issue is all the diagnosis I was told or plan of action is to surgically remove it but she is 17 and I don’t want the surgery to kill her. But at this point the tumor is bleeding. All the time. She doesn’t show discomfort or seem to care when I am cleaning it or bandaging it.
Sept. 28, 2020
Answered by Dr. Michele K. DVM
32 Recommendations
Thank you for your question.
If you are not comfortable with the surgery to remove it, you have the option to keep it clean, and covered, and that may be how she lives. I doubt there are any other therapies for a bleeding tumor other than surgical removal, but that may not be something that you opt to do. You can discuss with your veterinarian that you do not want her to have the surgery, and see if there is anything that they can recommend to help keep it clean, since it will likely not get better.
I hope that all goes well and she continues to have a happy life!
Oct. 4, 2020
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Pit bull
Sam
11 Years
0 found this helpful
0 found this helpful
My pet has the following symptoms:
Diarrhea
My 11 year old male pit bull has been having issues with defecating recently, and often will have diarrhea, his anus will sometimes bleed because of it. We clean it whenever that happens, and today when cleaning it i noticed there was a large red bump about the size of a dime protruding from the left side of his anal cavity. He is a healthy dog, but he is getting older. From what I’ve seen online I think it could be a tumor but I haven’t found an exact match to what I saw on him so I am not sure.
India Street Dog
Eunice
9 Years
1 found this helpful
1 found this helpful
My pet has the following symptoms:
Peri-Anal Tumor
My spayed female dog had a peri-anal mass removed and the lab report state" benign adnexal tumor, peri anal tumor upper margin, lower margin and deep resection margin are not free. Lateral margins are free" Does this mean she has an adenocarcinoma? We live in Myanmar now and don't have access to very modern veterinary care. Can you recommend our best way to move forward? She seems completely fine and pain-free. Thank you.
