My Dog Has a Lump Near Their Anus

By Laura GarcĂ­a Ortiz, Veterinarian specialized in feline medicine. May 16, 2021
My Dog Has a Lump Near Their Anus

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Checking the perianal area of our dog may not be the most pleasant aspect of basic dog care, but it is a vital one. A lump forming in this area can be fairly common, especially in older dogs. This is often due to impacted anal glands which may need expressed periodically. However, if there is a lump near the anus which is not due to an impacted gland, it is possible the dog has developed a perianal tumor. There are three main types of perianal tumors in dogs, some of which are relatively benign. Others may require medical intervention due to possible malignancy.

Although a healthy dog will lick their private area often, you will likely first notice a perianal tumor because they are licking it more than usual. If you discover your dog has a lump near their anus, it is important you know what you can expect in terms of diagnosis and treatment. AnimalWised explains this and more in our article about perianal tumors in dogs.

You may also be interested in: My Cat Has Lumps Under Their Skin

Types of perianal tumors in dogs

Whether you notice your dog is licking their private area more than usual or you see the lump itself, we need to know its underlying cause. The perianal area itself extends between the dog's anus and genitals. Since it is an area which contains many nerve endings, it can be incredibly sensitive. When they sustain an injury or develop a pathology in this area, the pain levels can be very high.

There are two important structures near the anus which can become inflamed:

  • Anal sacs: these are glands which appear at the side of the anus, between the external and internal anal sphincters. Their function is to secrete a fluid which has two main purposes. Firstly, it helps lubricate the anus for defecation. Secondly, the smell of the fluid helps other dogs to both recognize the individual, as well as find out certain information about them. The anal glands can become impacted, often due to poor hygiene in the area. Abscesses can develop which become very large and may need draining by a veterinarian.
  • Perianal glands: also called circumanal or hepatoid glands, these glands contain various hormone receptors (including androgens, estrogens and growth hormone). They are located in the subcutaneous tissue that surrounds the dog's anus. These are sebaceous-type glands, but do not secrete fluid.

Different types of tumors can appear in the perineal area, the most common being the following:

  • Perianal adenoma: a mass is observed at the base of the tail or in the perianal area with progressive and painless growth. Although relatively benign, it can ulcerate. It occurs more frequently in older non-castrated males, being the most prevalent tumor affecting them. However, it is also seen in females, especially in sterilized ones.
  • Perianal adenocarcinoma: another tumor of the perianal glands, it shares similar characteristics to adenomas. However, it is malign and aggressive. It can appear in dogs of any age and any sex.
  • Anal sac adenocarcinoma: it is the most common tumor in spayed and non-spayed females, as well as older dogs in general. Hypercalcemia (increased calcium in the blood) occurs in this tumor.

It should be noted that certain dog breeds are more predisposed to perianal tumors than others. These breeds include:

  • Cocker Spaniel
  • Fox Terrier
  • Breeds of Nordic origin
  • Large breeds
My Dog Has a Lump Near Their Anus - Types of perianal tumors in dogs

Symptoms of perianal tumors in dogs

Even when we detect a lump, dogs initially display neither pain nor associated symptoms in the early stages of perianal tumor development. Over time, as the tumor becomes enlarged, they can present colorectal obstruction and perianal pain. Both symptoms of the tumor can result in defecation being very difficult and painful. Over time, if the area becomes infected, they can develop related fever, malaise and anorexia.

Perianal adenocarcinomas are more aggressive. Clinical signs can include loss of appetite, pain and lethargy. They have a high possibility of producing hypercalcaemia as part of paraneoplastic syndrome (a set of symptoms associated with tumors). Clinical signs derived from the damage caused by this increase in calcium at the renal level, such as polyuria/polydipsia (urinating and drinking more than usual, respectively) can develop.

This paraneoplastic syndrome can also occur in adenocarcinomas of the anal sacs, but does so to a lesser extent (around 25-50% of dogs).

In summary, dogs can manifest the following symptoms if they have perianal tumors:

  • Perianal pain
  • Bad smell in the perianal region
  • Insistent licking of the area
  • Bleeding from the tumor
  • Drag of the back of the dog
  • Ulceration
  • Secondary infections
  • Anal itching
  • Anorexia
  • Polyuria
  • Polydipsia
  • Lethargy
  • Apathy
  • Fever
  • Fistulas
  • Lack of appetite
  • Weight loss
  • Colorectal obstruction
  • Constipation
  • Hematochezia (blood in the stool)
  • Disquecia (pain when defecating)
  • Tenesmus (difficulty in defecating)

These tumors have a high capacity to metastasize. They first invade the regional lymph nodes (inguinal and pelvic) and later the dog's internal organs.

Diagnosis of perianal tumor in dogs

When a veterinarian sees a lump near our dog's anus and suspects a malignant tumor, they will likely perform diagnostic imaging tests to determine if the tumor is malignant. They will also look for potential metastases since 50 to 80% of perianal tumors have metastasized by time of diagnosis.

The imaging techniques used include abdominal ultrasound to asses lymph nodes and other internal tissues. Radiography (x-ray) is useful for imaging tests in the thoracic organs, especially the lungs. Blood tests for dogs are useful in determining possible hypercalcemia and kidney damage in adenocarcinomas.

Treatment of perianal tumors in dogs

The main treatment for perianal tumors in dogs is surgical removal. However, this will depend on the type of tumor and whether it has metastasized. For this reason, treatment can vary.

  • In the case of perianal adenomas, since they are so closely related to the hormones of non-castrated males, they must be castrated to reduce the risk of future recurrences. In doing so, we can reduce the probability of reducing it by 90%.
  • When tumors are malignant and have metastasized, a complete removal with surgical edges should be performed. Post-surgical treatment with chemotherapy and radiation therapy will likely be administered.In cases of damage to kidney function and hypercalcemia, specific treatment with fluid therapy and drugs should be administered before surgery to reduce anesthetic risk.
  • When the size of the lymph nodes makes defecation difficult, they must be removed to facilitate this process.

As soon as we spot a lump near our dog's anus, we need to take them to a veterinarian. They will be able to diagnose the problem, whether it is a perianal tumor or one of the pathologies below.

Other causes of a lump near a dog's anus

Although a perianal tumor is one of the most worrying reasons why a dog might have a lump near their anus, it is not the only one. As stated above, the anal glands of a dog can become impacted. This is when the ducts of the anal sacs are obstructed, often with fecal matter from the anus. When this happens, the fluid cannot be secreted, causing the glands to inflame and develop into a lump.

To remove the lump, the first thing to be done is to drain the anal sacs. We can drain them ourselves, but it is best to see a veterinarian to ensure it is performed correctly. Also, whether due to impaction or another cause, it is possible for the dog's anal gland to become infected. This will likely require antibiotic treatment in addition to draining.

When any part of the perianal area receives trauma, a wound can form. Since they are close to fecal matter, they can become easily infected. If not treated promptly, these infections can develop into abscesses. So too can ingrown hairs on their perianal area. These may also need draining and antibiotic treatment.

Finally, both parasites and allergic reactions can causes inflammation of the perianal area. Parasites can bury into the skin and form a lump. Treatment will require deworming after veterinary assessment. Allergic reactions often occur in this area because the dog sits on something to which it has an allergy. Determining the allergen is the first part of treatment, something which requires veterinary assistance.

Our article on how often to deworm a dog will help us to know more about preventing possible lumps on our dog's perianal area.

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

If you want to read similar articles to My Dog Has a Lump Near Their Anus, we recommend you visit our Other health problems category.

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