Surgical treatment remains the treatment of choice for cats and dogs diagnosed with intestinal tumors who are in otherwise good health.

Treatment options vary and depend on the type and stage of cancer. Common treatments include surgery, chemotherapy, radiation therapy, amputation, and immunotherapy. A combination of therapies may be used. Knowledge and treatment of cancer have increased significantly in the past three decades. Survival rates have also increased due to the increase prevalence of canine cancer treatment centers and breakthroughs in targeted drug development. Canine cancer treatment has become an accepted clinical practice and access to treatment for owners has widely expanded recently. Cancer-targeting drugs most commonly function to inhibit excessive cell proliferation by attacking the replicating cells. However, there is still a prevalent pharmacy gap in veterinary oncology.

There is one canine tumor vaccine approved by the USDA, for preventing canine melanoma. The Oncept vaccine activates T-cell responses and antibodies against tumor-specific tyrosinase proteins. There is limited information about canine tumor antigens, which is the reason for the lack of tumor-specific vaccines and immunotherapy treatment plans for dogs.

Success of treatment depends on the form and extent of the cancer and the aggressiveness of the therapy. Early detection offers the best chance for successful treatment. The heterogeneity of tumors makes drug development increasingly complex, especially as new causes are discovered. No cure for cancer in canines exist.

Some dog owners opt for no treatment of the cancer at all, in which case palliative care, including pain relief, may be offered. Regardless of how treatment proceeds following a diagnosis, the quality of life of the pet is an important consideration. In cases where the cancer is not curable, there are still many things which can be done to alleviate the dog's pain. Good nutrition and care from the dog's owner can greatly enhance quality of life.

Aggressive surgical removal of the tumor and any enlarged sublumbar lymph nodes is essential for treatment of the tumor and associated hypercalcaemia. There is a high recurrence rate, although removal of lymph nodes with metastasis may improve survival time. Radiation therapy and chemotherapy may be helpful in treatment. Severe hypercalcaemia is treated with aggressive IV fluid therapy using sodium chloride and medications such as loop diuretics (increased kidney excretion of calcium) and aminobisphosphonates (decreased calcium release from bones). A poorer prognosis is associated with large tumor size (greater than 10 cm), hypercalcaemia, and distante metastasis. Early, incidental diagnosis of small anal sac masses may lead to a better prognosis with surgery alone (ongoing study).

Treatments of cancer in cats usually consists of diagnosis and observation of the tumor to determine its type and size, the development of a treatment plan, the associated goals on the part of the treatment methods, and the regular evaluation of the overall health of the pet.

Treatment of VAS is through aggressive surgery. As soon as the tumor is recognized, it should be removed with very wide margins to ensure complete removal. Treatment may also include chemotherapy or radiation therapy. The most significant prognostic factor is initial surgical treatment. One study showed that cats with radical (extensive) initial surgery had a median time to recurrence of 325 days versus 79 days for cats with marginal initial excision. The expression of a mutated form of p53, a tumor suppressor gene, is found commonly in VAS and indicates a poorer prognosis.

The specific treatment will depend on the tumor's type, location, size, and whether the cancer has spread to other organs. Surgical removal of the tumor remains the standard treatment of choice, but additional forms of therapy such as radiation therapy, chemotherapy, or immunotherapy exist.

When detected early, skin cancer in cats and dogs can often be treated successfully. In many cases, a biopsy can remove the whole tumor, as long as the healthy tissues removed from just outside the tumor area do not contain any cancer cells.

Surgical treatment is recommended for cats and dogs diagnosed with primary liver tumors but not metastasis to the liver. There are not many treatment options for animals who have multiple liver lobes affected.

Because most bladder cancers are invasive into the bladder wall, surgical removal is usually not possible. The majority of transitional cell carcinomas are treated with either traditional chemotherapy or nonsteroidal anti-inflammatory drugs.

The prevention of feline cancer mainly depends on the cat's diet and lifestyle, as well as an ability to detect early signs and symptoms of cancer prior to advancement to a further stage. If cancer is detected at an earlier stage, it has a higher chance of being treated, therefore lessening the chances of fatality. Taking domesticated cats for regular checkups to the veterinarian can help spot signs and symptoms of cancer early on and help maintain a healthy lifestyle. Further, due to advancements in research, prevention of certain types of feline illnesses remains possible. A widely known preventative of feline leukemia virus is the vaccine which was created in 1969. Subsequently, an immunofloures-cent antibody (IFA) test for the detection of FeLV in the blood of infected cats was formulated. The IFA test was mainly used to experiment the chances of felines being exposed to cancer. The results showed that 33% of cats who were exposed to FeLV related diseases were at a higher risk for acquiring it, while the cats that were left unexposed were left unaffected. FeLV is either spread through contagion or infection and once infected it is possible for cats to stay that way for the rest of their lives.

Interaction with other Cats

Interaction with other cats with strains or diseases related to FeLV can be a great risk factor for cats attaining FeLV themselves. Therefore, a main factor in prevention is keeping the affected cats in quarantine from the unaffected cats. Stray cats, or indoor/outdoor cats have been shown to be at a greater risk for acquiring FeLV, since they have a greater chance of interacting with other cats. Domesticated cats that are kept indoors are the least vulnerable to susceptible diseases.

Vaccines

Vaccines help the immune system fight off disease causing organisms, which is another key to prevention. However, vaccines can also cause tumors if not given properly. Vaccines should be given in the right rear leg to ease tumor removal process. Vaccines given in the neck or in between the shoulder blades are most likely to cause tumors and are difficult to remove, which can be fatal to cats. Reducing the number of vaccinations given to a cat may also decrease the risk for it developing a tumor.

Spaying and Neutering

Spaying and neutering holds many advantages to cats, including lowering the risk for developing cancer. Neutering male cats makes them less subjected to testicular cancer, FeLV, and FIV. Spaying female cats lowers the risk for mammary cancer, ovarian, or uterine cancer, as it prevents them from going into heat. Female cats should be spayed before their first heat, as each cycle of heat creates a greater risk for mammary cancer. Spaying a female cat requires the removal of the ovaries and uterus, which would eliminate their chances of developing cancer in these areas.

Exposure to Sun

The risk of skin cancer increases when a cat is exposed to direct sunlight for prolonged periods. White cats, or cats with white faces and ears, should not be allowed out on sunny days. Between the hours of 10:00 am to 4:00 pm, it is recommended to keep domesticated cats indoors, as the sun is at its highest peak between these times. Sun block is also available for cats, which can help prevent skin irritation, and a veterinarian should be contacted to find out which brands are appropriate and to use on cats.

Exposure to Secondhand Smoke

Cats living in a smoker’s household are three times more likely to develop lymphoma. Compared to living in a smoke-free environment, cats exposed to secondhand smoke also have a greater chance of developing squamous cell carcinoma or mouth cancer. Cancer is also developed mostly due to the cat's grooming habits. As cats lick themselves while they groom, they increase chances of taking in the toxic, cancer-causing carcinogens that gather on their fur, which are then exposed to their mucus membranes.

Lifestyle

Providing a cat with the healthiest lifestyle possible is the key to prevention. Decreasing the amount of toxins, including household cleaning products, providing fresh and whole foods, clean and purified water, and reducing the amount of indoor pollution can help cats live a longer and healthier life. To lessen susceptibility to diseases, domesticated cats should be kept inside the household for most of their lives to reduce the risk of interacting with other stray cats that could be infected with diseases.

Treatment includes chemotherapy and, where practical, removal of the tumor with the affected organ, such as with a splenectomy. Splenectomy alone gives an average survival time of 1–3 months. The addition of chemotherapy, primarily comprising the drug doxorubicin, alone or in combination with other drugs, can increase the average survival time to 2-4 months, or more.

A more favorable outcome has been demonstrated in recent research conducted at University of Pennsylvania Veterinary School, in dogs treated with a compound derived from the Coriolus versicolor (commonly known as "Turkey Tail") mushroom:

“We were shocked,” Cimino Brown said. “Prior to this, the longest reported median survival time of dogs with hemangiosarcoma of the spleen that underwent no further treatment was 86 days. We had dogs that lived beyond a year with nothing other than this mushroom as treatment.”There were not statistically significant differences in survival between the three dosage groups, though the longest survival time was highest in the 100 mg group, at 199 days, eclipsing the previously reported survival time.

The results were so surprising, in fact, that the researchers asked Penn Vet pathologists to recheck the dogs’ tissue biopsies to make sure that the dogs really had the disease.

“They reread the samples and said, yes, it’s really hemangiosarcoma,” Cimino Brown said.

Chemotherapy is available for treating hemangiosarcoma, but many owners opt not to pursue that treatment once their dog is diagnosed.

“It doesn’t hugely increase survival, it’s expensive and it means a lot of back and forth to the vet for the dog,” Cimino Brown said. “So you have to figure in quality of life.”

This treatment does not always work. So, one should always be prepared for their pet to have the same survival time as a dog who is untreated.

Visceral hemangiosarcoma is usually fatal even with treatment, and usually within weeks or, at best, months. In the skin, it can be cured in most cases with complete surgical removal as long as there is not visceral involvement.

Depending on the pet's unique condition, there are several treatment options, including surgery, chemotherapy and radiation therapy. Treating the pain adequately is also of crucial importance to improve the pet's quality of life, especially if amputation is not performed.

The average age at which intestinal tumors are diagnosed ranges between 10–12 years for cats and 6 to 9 years for dogs. There are many different types of intestinal tumors, including lymphoma, adenocarcinoma, mast cell tumor, and leiomyosarcoma.

Removal of the mast cell tumor through surgery is the treatment of choice. Antihistamines, such as diphenhydramine, are given prior to surgery to protect against the effects of histamine released from the tumor. Wide margins (two to three centimeters) are required because of the tendency for the tumor cells to be spread out around the tumor. If complete removal is not possible due to the size or location, additional treatment, such as radiation therapy or chemotherapy, may be necessary. Prednisone is often used to shrink the remaining tumor portion. H2 blockers, such as cimetidine, protect against stomach damage from histamine. Vinblastine and CCNU are common chemotherapy agents used to treat mast cell tumors.

Toceranib and masitinib, examples of receptor tyrosine kinase inhibitors, are used in the treatment of canine mast cell tumors. Both were recently approved by the U.S. Food and Drug Administration (FDA) as dog-specific anticancer drugs.

Grade I or II mast cell tumors that can be completely removed have a good prognosis. One study showed about 23 percent of incompletely removed grade II tumors recurred locally. Any mast cell tumor found in the gastrointestinal tract, paw, or on the muzzle has a guarded prognosis. Previous beliefs that tumors in the groin or perineum carried a worse prognosis have been discounted. Tumors that have spread to the lymph nodes or other parts of the body have a poor prognosis. Any dog showing symptoms of mastocytosis or with a grade III tumor has a poor prognosis. Dogs of the Boxer breed have a better than average prognosis because of the relatively benign behavior of their mast cell tumors. Multiple tumors that are treated similarly to solitary tumors do not seem to have a worse prognosis.

Mast cell tumors do not necessarily follow the histological prognosis. Further prognostic information can be provided by AgNOR stain of histological or cytological specimen. Even then, there is a risk of unpredictable behavior.

Treatment is multifactorial. A diet very low in fat and high in high quality protein is essential. Treatment of humans can also involve the use of MCT (medium-chain triglycerides) oil and/or the drug octreotide. In dogs, fat soluble vitamins (A, D, E, and K) should be supplemented. Corticosteroid treatment may be required for life. Antibiotics can be used to treat bacterial overgrowth. With a very low serum albumin, transfusion with blood plasma or an infusion of hetastarch may be necessary to treat the signs until the diet can take effect. Lymphangiectasia is rarely cured but can remain in remission for a long time. It can be fatal when unresponsive to treatment.

Appearance and location of the tumor is enough to identify it as a mammary tumor. Biopsy will give type and invasiveness of the tumor. In addition, newer studies showed that certain gene expression patterns are associated with malignant behaviour of canine mammary tumors.

Surgical removal is the treatment of choice, but chest x-rays should be taken first to rule out metastasis. Removal should be with wide margins to prevent recurrence, taking the whole mammary gland if necessary. Because 40 to 50 percent of dog mammary tumors have estrogen receptors, spaying is recommended by many veterinarians. A recent study showed a better prognosis in dogs that are spayed at the time of surgery or that had been recently spayed. However, several other studies found no improvement of disease outcome when spaying was performed after the tumor had developed. Chemotherapy is rarely used.

Due to the high risk of recurrence and ensuing problems, close monitoring of dogs undergoing chemotherapy is important. The same is true for dogs that have entered remission and ceased treatment. Monitoring for disease and remission/recurrence is usually performed by palpation of peripheral lymph nodes. This procedure detects gross changes in peripheral lymph nodes. Some of the blood tests used in diagnosing lymphoma also offer greater objectivity and provide an earlier warning of an animal coming out of remission.

Complete cure is rare with lymphoma and treatment tends to be palliative, but long remission times are possible with chemotherapy. With effective protocols, average first remission times are 6 to 8 months. Second remissions are shorter and harder to accomplish. Average survival is 9 to 12 months. The most common treatment is a combination of cyclophosphamide, vincristine, prednisone, L-asparaginase, and doxorubicin. Other chemotherapy drugs such as chlorambucil, lomustine (CCNU), cytosine arabinoside, and mitoxantrone are sometimes used in the treatment of lymphoma by themselves or in substitution for other drugs. In most cases, appropriate treatment protocols cause few side effects, but white blood cell counts must be monitored.

Allogeneic and autologous stem cell transplantations (as is commonly done in humans) have recently been shown to be a possible treatment option for dogs. Most of the basic research on transplantation biology was generated in dogs. Current cure rates using stem cell therapy in dogs approximates that achieved in humans, 40-50%.

When cost is a factor, prednisone used alone can improve the symptoms dramatically, but it does not significantly affect the survival rate. The average survival times of dogs treated with prednisone and untreated dogs are both one to two months. Using prednisone alone can cause the cancer to become resistant to other chemotherapy agents, so it should only be used if more aggressive treatment is not an option.

Isotretinoin can be used to treat cutaneous lymphoma.

New vaccine protocols have been put forth by the American Association of Feline Practitioners that limit type and frequency of vaccinations given to cats. Specifically, the vaccine for feline leukemia virus should only be given to kittens and high risk cats. Feline rhinotracheitis/panleukopenia/calicivirus vaccines should be given as kittens, a year later and then every three years. Also, vaccines should be given in areas making removal of VAS easier, namely: as close as possible to the tip of the right rear paw for rabies, the tip of the left rear paw for feline leukemia (unless combined with rabies), and on the right shoulder—being careful to avoid the midline or interscapular space—for other vaccines (such as FVRCP). There have been no specific associations between development of VAS and vaccine brand or manufacturer, concurrent infections, history of trauma, or environment.

Cancer is the leading cause of death in dogs. It is estimated that 1 in 3 domestic dogs will develop cancer, which is the same incidence of cancer among men. Dogs can develop a variety of cancers and most are very similar to those found in humans. Dogs can develop carcinomas of epithelial cells and organs, sarcomas of connective tissues and bones, and lymphomas or leukemias of the circulatory system. Selective breeding of dogs has led certain pure-bred breeds to be at high-risk for specific kinds of cancer.

Veterinary oncology is the medical study of cancer in animals, and can be diagnosed and treated by specialized veterinarians called veterinary oncologists.

An anal sac adenocarcinoma is an uncommon and aggressive malignant tumor found in dogs that arises from the apocrine glandular tissue of anal sac. The disease exists in cats as well, but is much less common in that species. They are the second most common cancerous cause of hypercalcaemia (high serum calcium) in dogs, following T-cell lymphoma.

The most reliable test for EPI in dogs and cats is serum trypsin-like immunoreactivity (TLI). A low value indicates EPI. Fecal elastase levels may also be used for diagnosis in dogs.

In dogs, the best treatment is to supplement its food with dried pancreatic extracts. There are commercial preparations available, but chopped bovine pancreas from the butcher can also be used (pork pancreas should not be used because of the rare transmission of pseudorabies). Symptoms usually improve within a few days, but lifelong treatment is required to manage the condition. A rare side-effect of use of dried pancreatic extracts is oral ulceration and bleeding.

Because of malabsorption, serum levels of cyanocobalamin (vitamin B12) and tocopherol (vitamin E) may be low. These may be supplemented, although since cyanocobalamin contains the toxic chemical cyanide, dogs that have serious cobalamin issues should instead be treated with hydroxocobalamin or methylcobalamin. Cyanocobalamin deficiency is very common in cats with EPI because about 99 percent of intrinsic factor (which is required for cyanocobalamin absorption from the intestine) is secreted by the pancreas. In dogs, this figure is about 90 percent, and only about 50 percent of dogs have this deficiency. Cats may suffer from Vitamin K deficiencies. If there is bacterial overgrowth in the intestine, antibiotics should be used, especially if treatment is not working. In dogs failing to gain weight or continuing to show symptoms, modifying the diet to make it low-fiber and highly digestible may help. Despite previous belief that low-fat diets are beneficial in dogs with EPI, more recent studies have shown that a high-fat diet may increase absorption of nutrients and better manage the disease. However, it has been shown that different dogs respond to different dietary modifications, so the best diet must be determined on a case-by-case basis.

One possible sequela, volvulus (mesenteric torsion) is a rare consequence of EPI in dogs.

Compared to other breeds of dog, Scottish terriers have a much increased risk of developing transitional cell carcinoma.

A complete radical, surgical, "en bloc" resection of the cancer, is the treatment of choice in osteosarcoma. Although about 90% of patients are able to have limb-salvage surgery, complications, particularly infection, prosthetic loosening and non-union, or local tumor recurrence may cause the need for further surgery or amputation.

Mifamurtide is used after a patient has had surgery to remove the tumor and together with chemotherapy to kill remaining cancer cells to reduce the risk of cancer recurrence. Also, the option to have rotationplasty after the tumor is taken out exists.

Patients with osteosarcoma are best managed by a medical oncologist and an orthopedic oncologist experienced in managing sarcomas. Current standard treatment is to use neoadjuvant chemotherapy (chemotherapy given before surgery) followed by surgical resection. The percentage of tumor cell necrosis (cell death) seen in the tumor after surgery gives an idea of the prognosis and also lets the oncologist know if the chemotherapy regimen should be altered after surgery.

Standard therapy is a combination of limb-salvage orthopedic surgery when possible (or amputation in some cases) and a combination of high-dose methotrexate with leucovorin rescue, intra-arterial cisplatin, adriamycin, ifosfamide with mesna, BCD (bleomycin, cyclophosphamide, dactinomycin), etoposide, and muramyl tripeptide. Rotationplasty may be used. Ifosfamide can be used as an adjuvant treatment if the necrosis rate is low.

Despite the success of chemotherapy for osteosarcoma, it has one of the lowest survival rates for pediatric cancer. The best reported 10-year survival rate is 92%; the protocol used is an aggressive intra-arterial regimen that individualizes therapy based on arteriographic response. Three-year event-free survival ranges from 50% to 75%, and five-year survival ranges from 60% to 85+% in some studies. Overall, 65–70% patients treated five years ago will be alive today. These survival rates are overall averages and vary greatly depending on the individual necrosis rate.

Filgrastim or pegfilgrastim help with white blood cell counts and neutrophil counts. Blood transfusions and epoetin alfa help with anemia. Computational analysis on a panel of Osteosarcoma cell lines identified new shared and specific therapeutic targets (proteomic and genetic) in Osteosarcoma, while phenotypes showed an increased role of tumor microenvironments.

A perianal gland tumor is a type of tumor found near the anus in dogs that arises from specialized glandular tissue found in the perineum. Perianal glands do not exist in cats. It is also known as a hepatoid tumor because of the similarity in cell shape to hepatocytes (liver cells). It is most commonly seen in intact (not neutered) dogs and is the third most common tumor type in intact male dogs. There are two types of perianal gland tumors, perianal gland adenomas, which are benign, and perianal gland adenocarcinomas, which are malignant. Both have receptors for testosterone. Perianal gland adenomas are three times more likely to be found in intact male dogs than females, and perianal gland adenocarcinomas are ten times more common in male dogs than females. The most commonly affected breeds for adenomas are the Siberian Husky, Cocker Spaniel, Pekingese, and Samoyed; for adenocarcinomas the most commonly affected breeds are the Siberian Husky, Bulldog, and Alaskan Malamute.

Perianal gland tumors are located most commonly in the skin around the anus, but can also be found on the tail or groin. Adenomas are more common, making up 91 percent of perianal gland tumors in one study. Adenomas and adenocarcinomas look alike, both being round, pink and usually less than three centimeters in width. Adenocarcinomas are more likely to be multiple and invasive into the underlying tissue, and they can metastasize to the lymph nodes, liver, and lungs.

Both types should be removed and sent to a pathologist for identification. However, 95 percent of perianal gland adenomas will disappear after neutering the dog. Removing the tumor and neutering the dog at the same time will help prevent recurrence. Dogs with perianal gland adenocarcinomas should be treated with aggressive surgery and the radiation therapy and chemotherapy if necessary.

Mammary tumors are the third most common neoplasia in cats, following lymphoid and skin cancers. The incidence of mammary tumors in cats is reduced by 91 percent in cats spayed prior to six months of age and by 86 percent in cats spayed prior to one year, according to one study. Siamese cats and Japanese breeds seem to have increased risk, and obesity also appears to be a factor in tumor development. Malignant tumors make up 80 to 96 percent of mammary tumors in cats, almost all adenocarcinomas. Male cats may also develop mammary adenocarcinoma, albeit rarely, and the clinical course is similar to female cats. As in dogs, tumor size is an important prognostic factor, although for tumors less than three centimeters the individual size is less predictive. According to one study, cats with tumors less than three cm had an average survival time of 21 months, and cats with tumors greater than three cm had an average survival of 12 months. About 10 percent of cat mammary tumors have estrogen receptors, so spaying at the time of surgery has little effect on recurrence or survival time. Metastasis tends to be to the lungs and lymph nodes, and rarely to bone. Diagnosis and treatment is similar to the dog. There is a better prognosis with bilateral radical surgery (removing the both mammary chains) than with more conservative surgery. Doxorubicin has shown some promise in treatment.

Amputation is the initial treatment, although this alone will not prevent metastasis. Chemotherapy combined with amputation improves the survival time, but most dogs still die within a year. Surgical techniques designed to save the leg (limb-sparing procedures) do not improve the prognosis.

Some current studies indicate osteoclast inhibitors such as alendronate and pamidronate may have beneficial effects on the quality of life by reducing osteolysis, thus reducing the degree of pain, as well as the risk of pathological fractures.