Adenocarcinoma is a type of cancer that originates from the glandular and epithelial tissue, which is the lining of the internal organs. Adenocarcinoma can affect many parts of the body, but it is most commonly found in the gastrointestinal system of dogs, especially the stomach, intestines, and rectum. It can also occur in other organs, such as the anal glands, mammary glands, prostate, kidney, and uterus.
Adenocarcinoma is a malignant tumor that can grow rapidly, invade nearby tissues, and spread to other parts of the body through the blood or lymph vessels. Adenocarcinoma is more common in older dogs, usually over six years of age, and it does not seem to have a breed predisposition. However, some breeds may be more prone to certain types of adenocarcinoma, such as Bernese Mountain Dogs for histiocytic sarcoma.
Adenocarcinoma is a serious and often fatal disease that requires prompt diagnosis and treatment. This article will discuss the causes, symptoms, diagnosis, treatment, prevention, prognosis, and dog breeds at the highest risk of adenocarcinoma in dogs.
What is Adenocarcinoma?
Adenocarcinoma is a type of cancer that arises from the glandular and epithelial cells that line the internal organs. These cells produce and release various substances, such as mucus, hormones, enzymes, and milk. When these cells become abnormal and multiply uncontrollably, they form a mass of tissue called a tumor. The tumor can grow larger and interfere with the normal function of the affected organ. It can also invade the surrounding tissues and damage them. Moreover, the tumor can break off and travel through the blood or lymph vessels to other parts of the body and form new tumors. This process is called metastasis.
Adenocarcinoma can develop in any organ that has glandular and epithelial tissue, but it is most frequently seen in the gastrointestinal system of dogs. The most common locations are:
- Stomach: Adenocarcinoma of the stomach can affect any part of the stomach, but it is more often found in the pylorus (the lower part of the stomach that connects to the small intestine). It can cause ulcers, bleeding, obstruction, and inflammation of the stomach.
- Intestine: Adenocarcinoma of the intestine can affect any part of the small or large intestine, but it is more common in the colon (the last part of the large intestine). It can cause diarrhea, constipation, blood or mucus in the stool, obstruction, and inflammation of the intestine.
- Rectum: Adenocarcinoma of the rectum can affect any part of the rectum (the last part of the large intestine that connects to the anus). It can cause straining to defecate, blood or mucus in the stool, obstruction, and inflammation of the rectum.
Other organs that can be affected by adenocarcinoma include:
- Anal glands
- Mammary glands
The diagnosis of adenocarcinoma in dogs depends on the location and symptoms of the tumor. The veterinarian will perform a complete physical examination and ask for a thorough history of the dog’s health and behavior. The veterinarian may also perform some tests to confirm the diagnosis and determine the extent of the disease. These tests may include:
- Blood tests: Blood tests can reveal anemia (low red blood cell count), which is common in dogs with adenocarcinoma due to chronic bleeding from the tumor. Blood tests can also show high calcium levels (hypercalcemia), which is a sign of prostatic or mammary adenocarcinoma. Blood tests can also help evaluate the function of other organs, such as the liver and kidney, that may be affected by the tumor or its treatment.
- Fecal tests: Fecal tests can detect blood or mucus in the stool, which is a sign of intestinal or rectal adenocarcinoma. Fecal tests can also help rule out other causes of gastrointestinal problems, such as parasites or infections.
- Urinalysis: Urinalysis can detect blood or protein in the urine, which is a sign of kidney or prostatic adenocarcinoma. Urinalysis can also help evaluate the function of the kidney and rule out other causes of urinary problems, such as infections or stones.
- X-rays: X-rays can show the size and shape of the affected organ and reveal any abnormalities, such as masses, ulcers, obstructions, or inflammation. X-rays can also show if the tumor has spread to other parts of the body, such as the lungs, bones, or abdomen.
- Ultrasound: Ultrasound is a non-invasive imaging technique that uses sound waves to create a picture of the internal organs. Ultrasound can show more details than X-rays and help locate and measure the tumor. Ultrasound can also guide a needle biopsy, which is a procedure that involves taking a small sample of tissue from the tumor for microscopic examination.
- Endoscopy: Endoscopy is a procedure that involves inserting a thin tube with a camera and light at its tip into an opening of the body, such as the mouth, anus, or vagina. Endoscopy can allow direct visualization of the tumor and its surrounding tissues. Endoscopy can also help take a biopsy or remove small tumors.
- Biopsy: Biopsy is the definitive test for diagnosing adenocarcinoma in dogs. A biopsy involves taking a small sample of tissue from the tumor and examining it under a microscope. Biopsies can reveal the type, grade, and stage of cancer. A biopsy can be obtained by using a needle guided by ultrasound or endoscopy or by performing surgery.
The treatment of adenocarcinoma in dogs depends on the location, type, grade, and stage of the tumor, as well as the overall health and condition of the dog. The main goals of treatment are to remove or shrink the tumor, prevent or slow down its spread, relieve the symptoms, and improve the dog’s quality of life. The main treatment options for adenocarcinoma in dogs are:
- Surgery: Surgery is the most common and effective treatment for adenocarcinoma in dogs, especially if the tumor is localized and has not spread to other parts of the body. Surgery involves removing the tumor and some of the surrounding healthy tissue to ensure complete removal. Surgery can also remove any affected lymph nodes or other organs. Surgery can cure some types of adenocarcinoma, such as intestinal or rectal, if detected early and completely removed. However, surgery may not be possible or advisable for some types of adenocarcinoma, such as stomach or prostatic, due to the difficulty of removing all of the tumor tissue or the risk of complications.
- Chemotherapy: Chemotherapy is the use of drugs that kill or stop the growth of cancer cells. Chemotherapy can be given orally, intravenously, or directly into the tumor. Chemotherapy can be used as an alternative to surgery, especially in cases where tumors have metastasized or cannot be removed completely. Chemotherapy can also be used as an adjuvant therapy, which means it is given after surgery to kill any remaining cancer cells and prevent recurrence. Chemotherapy can prolong the survival time and improve the quality of life of dogs with adenocarcinoma. However, chemotherapy has limited effectiveness for some types of adenocarcinoma, such as mammary or prostatic adenocarcinoma. Chemotherapy can also cause side effects, such as nausea, vomiting, diarrhea, hair loss, low blood cell counts, and increased susceptibility to infections.
- Radiation therapy: Radiation therapy is the use of high-energy rays that damage or destroy cancer cells. Radiation therapy can be delivered externally by a machine that aims at the tumor site or internally by placing radioactive material inside or near the tumor. Radiation therapy can be used as a primary treatment for adenocarcinoma in dogs that cannot undergo surgery or chemotherapy. Radiation therapy can also be used as adjuvant therapy after surgery or chemotherapy to prevent recurrence or treat residual disease. Radiation therapy can shrink tumors and relieve symptoms such as pain, bleeding, obstruction, or inflammation. However, radiation therapy has limited effectiveness for some types of adenocarcinoma, such as intestinal or rectal adenocarcinoma. Radiation therapy can also cause side effects, such as skin irritation, hair loss, inflammation, or infection of the treated area.
The choice of treatment for adenocarcinoma in dogs depends on many factors, such as the type, location, stage, and grade of the tumor, the overall health and condition of the dog, the availability and cost of the treatment options, and the preference and expectations of the owner. Your veterinarian or veterinary oncologist will discuss the pros and cons of each treatment option and recommend the best course of action for each individual case. Sometimes, a combination of treatments may be used to achieve the best results. In some cases, palliative care may be the only option to provide comfort and relief to the dog.
There is no sure way to prevent adenocarcinoma in dogs, as the exact causes are still unknown. However, there are some suggestions that owners can do to minimize their dogs’ risk of getting this type of cancer, such as:
- Provide a healthy diet: A balanced and nutritious diet can help support the immune system and prevent chronic diseases, including cancer. Avoid feeding your dog foods that are high in fat, sugar, salt, or preservatives. Choose foods that are appropriate for your dog’s age, size, breed, and activity level. Consult your veterinarian for advice on the best diet for your dog.
- Maintain a healthy weight: Obesity can increase the risk of many health problems, including cancer. Keep your dog at a healthy weight by providing adequate exercise and portion control. Avoid overfeeding or giving too many treats or table scraps to your dog. Monitor your dog’s weight regularly and adjust the diet accordingly. Ask your veterinarian for guidance on how to determine your dog’s ideal weight and body condition score.
- Regular vet checkups: See your veterinarian at least once a year for a routine wellness exam and preventive care. Your veterinarian can detect any signs of illness or disease early and provide appropriate treatment. Your veterinarian can also advise you on the best vaccination and parasite prevention schedule for your dog. Follow your veterinarian’s recommendations on screening tests or diagnostic procedures that may be needed for your dog based on its age, breed, or health status.
- Spay or neuter your dog: Spaying or neutering your dog can reduce the risk of some types of cancer, such as mammary or uterine adenocarcinoma in female dogs and prostatic adenocarcinoma in male dogs. Spaying or neutering can also prevent unwanted pregnancies and behavioral problems. Consult your veterinarian on the best time to spay or neuter your dog.
- Limit sun exposure: Sun exposure can increase the risk of skin cancer in dogs, especially those with light-colored or thin hair coats. Limit your dog’s exposure to the sun, especially between 10 am and 3 pm when the sun is strongest. Provide shade and fresh water for your dog when outdoors. Apply sunscreen to areas that are not covered by hair, such as the nose, ears, belly, or groin. Choose a sunscreen that is safe for dogs and does not contain zinc oxide or salicylates.
- Avoid exposure to toxins: Toxins can damage the DNA of cells and cause mutations that lead to cancer. Avoid exposing your dog to toxins such as pesticides, herbicides, or tobacco smoke. Keep your dog away from areas that are sprayed with chemicals or pesticides. Do not smoke around your dog or expose it to secondhand smoke. Store any toxic substances safely and securely away from your dog’s reach.
The prognosis for dogs with adenocarcinoma depends on the location, type, stage, and grade of the tumor, as well as the treatment and response of the dog. In general, adenocarcinoma is a serious and often fatal disease that has a poor prognosis. Without any treatment, dogs with adenocarcinoma may only live for a few months to a year and a half after diagnosis. Treatment options may improve dogs’ survival time and quality of life with adenocarcinoma but rarely cure the disease. Some treatments may have side effects that can affect the dog’s well-being.
The prognosis for dogs with adenocarcinoma varies depending on the location of the tumor. For example:
- Stomach: Life Expectancy for dogs with stomach adenocarcinoma is usually two months, regardless of treatment.
- Intestine: Life Expectancy for dogs with intestinal adenocarcinoma is about ten months with surgery and chemotherapy. Surgery can cure some cases of intestinal adenocarcinoma if detected early and completely removed.
- Rectum: Life Expectancy for dogs with rectal adenocarcinoma is about eight months with surgery and chemotherapy. Surgery can cure some cases of rectal adenocarcinoma if detected early and completely removed.
- Anal glands: Life Expectancy for dogs with anal gland adenocarcinoma is between 12 and 24 months with surgery and chemotherapy. Dogs whose anal gland tumors are successfully removed can live for up to four years, but this is usually when the cancer is caught very early.
- Mammary glands: Life Expectancy for dogs with mammary gland adenocarcinoma depends on the size, number, and location of the tumors, as well as the presence or absence of metastasis. Dogs whose mammary tumors are small, solitary, and confined to one gland have a better prognosis than dogs whose mammary tumors are large, multiple, or spread to other glands or organs. Spaying can improve the prognosis for dogs with mammary gland adenocarcinoma.
- Prostate: Life Expectancy for dogs with prostatic adenocarcinoma is usually less than six months, regardless of treatment. Surgery is rarely possible or effective for prostatic adenocarcinoma due to the difficulty of removing all of the tumor tissue or the risk of complications. Chemotherapy has limited effectiveness for prostatic adenocarcinoma due to drug resistance.
- Kidney: Life Expectancy for dogs with kidney adenocarcinoma is usually less than six months, regardless of treatment. Surgery is rarely possible or effective for kidney adenocarcinoma due to the difficulty of removing all of the tumor tissue or the risk of complications. Chemotherapy has limited effectiveness for kidney adenocarcinoma due to drug resistance.
- Uterus: Life Expectancy for dogs with uterine adenocarcinoma depends on the stage and extent of the disease, as well as the treatment. Dogs whose uterine tumors are localized and confined to the uterus have a better prognosis than dogs whose uterine tumors have spread to other organs or lymph nodes. Spaying can improve the prognosis for dogs with uterine adenocarcinoma.
The prognosis for dogs with adenocarcinoma also depends on other factors, such as the dog’s age, breed, health status, and temperament, as well as the owner’s preferences and expectations. Some owners may opt for aggressive treatment to prolong their dog’s life as much as possible, while others may choose palliative care to provide comfort and relief to their dog. Some owners may decide to euthanize their dog when its quality of life is severely affected or its clinical signs cannot be controlled. These decisions are personal and should be made in consultation with the veterinarian or veterinary oncologist who knows the dog’s condition best.
Dog Breeds at Highest Risk
Adenocarcinoma can affect any dog breed, but some breeds may be more prone to certain types of adenocarcinoma than others. For example:
- Bernese Mountain Dogs are more likely to develop histiocytic sarcoma. This aggressive and relatively rare cancer originates from histiocytes (a type of immune cell) and can affect various organs, such as the spleen, liver, lungs, or skin.
- Boxers are more likely to develop lymphoma, mast cell tumors, brain tumors, and skin hemangiosarcoma.
- Rottweilers, Great Danes, and other large and giant breed dogs are prone to osteosarcoma, a type of bone cancer that usually affects the limbs.
- Labrador Retrievers are more likely to suffer from lymphoma and hemangiosarcoma.
- German Shepherds are more prone to hemangiosarcoma and lymphoma.
- Beagles are prone to lymphoma and bladder cancer.
- Cocker Spaniels are more susceptible to melanoma, a type of skin cancer that can also affect the mouth or eyes.
- Bouvier des Flandres are more at risk of developing gastrointestinal cancer, such as stomach or intestinal adenocarcinoma.
- Standard Poodles are more prone to mammary gland adenocarcinoma and squamous cell carcinoma, a type of skin cancer that can also affect the mouth or ears.
- Bichon Frises are more likely to develop bladder cancer, especially transitional cell carcinoma.
Not all dogs will develop cancer or other health issues, regardless of what their breed is supposed to be prone for. In fact, many dogs will never experience or suffer from horrible diseases like these; some of these have simply been seen at a higher rate in certain breeds.
Adenocarcinoma is a type of cancer that affects the glandular and epithelial tissue of various organs in dogs. It is a serious and often fatal disease that requires prompt diagnosis and treatment. The symptoms, diagnosis, treatment, prevention, prognosis, and dog breeds at the highest risk of adenocarcinoma vary depending on the location of the tumor. Owners should be aware of the signs of cancer in their dogs and consult their veterinarian or veterinary oncologist if they notice any changes in their dog’s health or behavior. Early detection and treatment can improve the outcome and quality of life of dogs with adenocarcinoma.