Cancer in cats

Similarly to humans, cancer is the leading cause of death among older cats. It is caused by uncontrolled cell growth, and affects a wide range of cell types and organs in the body. Feline cancer initially manifests as a lump or bump on any parts of the body. It rapidly grows in the affected cell; attaches itself to the tissue under the skin in that area; and, depending on the tumour, it can spread to other parts of the body.[1] Although cancer accounts for approximately 50% of feline deaths each year, it can be successfully treated if diagnosed early.[2]

While the causes of cancer in cats are unknown, feline leukemia virus is suspected to be a prime contributor.[2] Other factors suspected to increase rates of feline cancer include toxins from the environment, second hand smoking, excessive grooming, or licking parts of the body that have been in contact with an environmental toxin.[2]

Cancer can be detected early on by observing for certain signs and symptoms. Common diagnosing methods include physical examination, x-rays, ultrasounds, cytology, blood tests, urine tests, and nuclear scans. Depending on the type of cancer and its level of progress, surgery, radiation, chemotherapy, or immunotherapy may be utilized to treat for cancer. Although research has been slow for causes and treatment of feline cancers, there have been advancements in radiation therapy, as well as newer and improved chemotherapy procedures.[2]

Signs and symptoms

Although cats are diagnosed with cancer at lower rates than dogs or humans, the types of cancer and symptoms are identical. Cancer in cats can occur in any location or body system,[3] and most symptoms can be detected externally.[2] However, to reach a definitive diagnosis, further tests such as blood and urine tests, cytology, and biopsy are required.[4] Due to the excessively aggressive nature of cancer in cats, it is advisable for owners to take their cat to a veterinarian for an examination following occurrence of any symptom to prevent spreading.[1]

General signs of feline cancer

While each type of cancer has its own distinctive symptoms, most of them can indicate their presence by the occurrence and the prolonged presence of any common symptom.[1] Some of the general symptoms of cancer in cats are:[3]

Note that ravenous hunger, while a sign of other diseases like hyperthyroid, can also be a sign of cancer.

Symptoms of common types of cancer

Lymphoma

Lymphoma is the most common form of cancer in cats, which is often associated with feline leukemia virus, and accounts for 25 percent of all cases.[3] Feline lymphoma usually strikes the digestive system, causing excessive vomiting and diarrhea.[5] Other common symptoms of lymphoma in cats include swollen lymph nodes, loss of appetite, weight loss, and difficulty breathing.[5]

Feline skin tumors

Skin tumors are less common in cats; and although most cats are vulnerable, white cats are especially prone to this type of tumor. Feline skin tumor manifests as a visible lump on the skin, mostly affecting vision, smell, or eating.[6] Benign tumors take several years to develop and are more difficult to detect due to their freely movable nature.[7] The only indicator of benign tumors is self-trauma, which can be caused by excessive licking by the cat.[7]

Mammary gland tumors

See also: Mammary tumor

Mammary gland tumors are the third common type of cancer in older female cats, with the most common symptom manifesting as a lump in the breast tissue.[3] The tumor is typically firm and nodular, and adheres to the overlying skin.[8] Nipples may also appear to be red and swollen, oozing yellowish fluid.[8]

Abdominal Tumors

Abdominal tumor is among the rarest forms of cancer in cats, and most difficult to treat successfully before progressing to an advanced stage.[9] The main symptoms include abdominal enlargement,[3] vomiting (often with blood), weight loss due to poor digestion, and weakness.[9]

Treatment

Types of Tumors

When cancer is determined as the illness affecting the cat, an important part of the healing process is determining the type of cancerous tumor present. This is helpful in selecting the best therapeutic approach and increases chances of recovery.[10]

  • Adenomas are tumors that affect sebaceous glands predominantly in the limbs, the eyelids and the head. They are also commonly-found in the ears (and ear canals) of cats and may lead to the development of hyperthyroidism. These adenomas typically appear as cauliflower, wart-like growths with a pink-orange tinge. They can be diagnosed either through their physical appearance or a biopsy testing.
  • Lipomas are tumors that occur within the fatty tissues and reside as soft, fluctant round masses that adhere tightly to surrounding tissue (typically to organs and the membrane linings of body cavities). For this type of tumor, surgical removal is the common treatment choice. However, removal is not guaranteed as the tumor sometimes adheres strongly to surrounding muscles and tissues.
  • Lymphoma- lymphosarcoma (LSA) is common among cats with FeLV infections. Lymphoma- lymphosarcoma affects the intestines and other lymphatic tissues (commonly the abdominal organs). Cats with LSA may be affected by a loss of appetite, weight loss, vomiting, diarrhea, bloody stool, and constipation. LSA can be diagnosed through lymph node cytology, biopsy, radiographs, and ultrasounds.
  • Myeloproliferative tumors are types of genetic disorders passed through generations. It can affect the bone marrow, white blood cells, red blood cells, and platelets. Similar symptoms occur in blood clotting disorders, they include weakness, labored breathing, pale muscus membranes and a loss of appetite. Treatment options for these tumors include chemotherapy, and bone marrow transplants.
  • Melanomas are not typically common in cats but when they are, they manifest as basal cell tumors. These tumors are benign in nature, but are firm and raised from the surface of the skin. They are commonly found around the neck, head, ears, and shoulder regions and can be treated through chemotherapy or radiation therapy.
  • Squamous cell carcinomas affect areas that lack natural pigmentation (oral cavity, tonsils, lips, nose, eyelids, external ear, limbs, toes and nails), or areas that are under constant trauma and irritation. They are diagnosed through biopsy testing. Treatment options include: surgery, cryotherapy, hyperthermia, chemotherapy, and radiation.
  • Mast cell tumors are either sole or multiple skin nodules that may be ulcerated and pigmented. They can be located on any part of the cat's body. Diagnosis is made by cytological examination and biopsy of the tumor.
  • Osteosarcoma are tumors that mainly affect the joints, bones and lungs. Osteosarcoma can lead to swelling, lameness, coughing, and breathing difficulties. Diagnosis is done by radiographs usually followed by a biopsy. Treating osteosarcoma treatment involves aggressive surgical intervention that may lead to amputation of the affected limb.
  • Fibrosarcomas arise from the fibrous tissues just beneath the skin. They may be present as solitary, irregular masses on the skin. Diagnosis is made through biopsy evaluation which is followed by treatment with surgery, radiation, and chemotherapy.

Diagnosing Methods

As soon as a tumor is detected, diagnosing the type of cancer remains a primary objective, as it helps determine the best possible treatment by the analysis of the structure of the tumor and cancer cells.[10]

X-ray of FeLV-positive cat with lung cancer
X-ray of FeLV-positive cat with lung cancer
  • Physical examination is the most common diagnostic method because typically most tumors can be diagnosed using physical examination with visual observation and manual palpation.
  • X-rays (radiography) are divided by two types: plain film and constrat techniques. They are commonly used to present tumors of the lung, gastrointestinal tract, bladder, and other internal organs.
  • Ultrasoundgraphy is used to visualize internal bodily structures, and permits for the diagnosis of internal tumors. It is also a way to see internal cysts (which may become tumors) and to see the size and structure of the organs.
  • Cytology involves taking cells from the affected area, such as mammary gland secretions, nasal secretions, respiratory secretions, bone marrow and lymph nodes. This is typically the method used for ruling out bumps that may be abscesses, cysts, or granulomas.
  • Nuclear Scans are used to view the liver, thyroid, lung, spleen, kidney and bones. It allows for diagnosis with very few effects on the pet.
  • Blood Tests are completed to through microscopic and biochemical analysis of the blood taken. They are completed to confirm or discount suspected cases of feline leukemia or feline immunodeficiency virus.

Treatment Methods

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.

  • Surgery can be utilized if the tumor is localized and accessible, with the goal of removing all malignant cells before any spreading occurs to other regions of the pet. It continues to be the most common choice for treatment of cancer in felines and other pets.
  • Radiation is used to control or cure cancers provided: the tumor targeted falls in the range suitable for radiation, no radiosensitive organs are involved, and it can be meta-sized. It can be done either internally through implants (branchytherapy), or externally by using radioactive beams (teleotherapy). This destroys the DNA of the cells and ensures reproduction chances are diminished.
  • Chemotherapy used to be prohibited within veterinary medicine. Today, however, a wide range of anti-cancer drugs are readily available. It breaks down the chromosomes of the cell or tumor, so cell division becomes impossible. This stops the affected cells to reproduce or spread to other parts of the body. Side effects include bone marrow depression, nausea, hair loss and hemorrhaging, with a major issue being that it does not work effectively against large tumors.
  • Immunotherapy works on the premise that many cancers occur because of a defect in the organism's immune system. It asserts that the tumor would have been suppressed had the organism's immune system been functioning normally. Rather than employing external procedures, it stimulates the animal's own system to fight the cancer. A good example of this methodology is the use of Monoclonal anti-bodies in triggering the body's immune system to fight any cells to which it attaches.

Prevention

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.[11] Subsequently, an immunofloures-cent antibody (IFA) test for the detection of FeLV in the blood of infected cats was formulated.[11] 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.[11] 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.[11]

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.[12]

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.[12]

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.[13]

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.[14]

Exposure to Secondhand Smoke

Cats living in a smoker’s household are three times more likely to develop lymphoma.[15] 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.[12]

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.[16]

Research

Laboratory cats have been used in research for a wide range of diseases including stroke and diabetes[17] to AIDS.[18] Less than 1% of research on animal illnesses have been dedicated to cats.[19]

Despite opposition from organizations such as those advocating animal rights,[20] controversial animal testing is still used in cancer research centers. These research practices are continually being conducted on the basis that its benefits to humans outweigh the costs to humans, despite the unfair costs to innocent non-human animals.[21] In some US states, animal testing laboratories get some of their feline test subjects from animal shelters.[22]

According to Kim Sterling, associate teaching professor of oncology at the University of Missouri College of Veterinary Medicine, the use of small animals in predicting human health care procedures is of significant benefit to humans because they are affected in similar, but not exactly the same, ways by the same diseases. This is the same analogy used in reference to cats and their unwilling role in advancing human cancer treatment research.[23]

It is research like this that has led to a potential link between cat parasites and brain cancer in humans. Cats carry the parasite toxoplasma gondii. According to research ecologist Kevin Lafferty, of the University of California, Santa Barbara, this parasite is known to “behave in ways that could stimulate cells towards cancerous states”.[24] Therefore, research on cats with this parasite can help to better understand the risks of brain cancer for humans in contact with such cats.

Cats have also been used to further studies in the field of Cancer stem cell research.[25] Small animals, like cats, experience faster rates of cancer development. As a result, they are good preclinical models for understanding processes like immortalization and its role in promoting cancerous tumors.[26] The absence of immortalization means a cell can no longer undergo malignant transformation. Since these transformations are the basis for cancerous cell reproduction, this research can prove useful for future cancer treatments and understanding how to stop the spread of cancer in the body.

However, feline cancer research is not limited to what laboratory cats can do for other animals, there is also research being done by humans to see what can be done to improve treatment options for feline cancer. Advances, though slower than that in other animals, are being made in the field of feline cancer. This includes advances in chemotherapy research, immunization protocols and radiation therapy. In addition, there are clinical trials offering trial research treatment options for cats with cancer.[27]

One of such treatments is the cat's claw. Although they share the same name, the cat’s claw (also known as Uncaria tomentosa or uña de gato) [28] refers not to the animal cat but to a native plant of the Amazon Rainforest in Peru, South America. Cat's claw is still under research for its immunotherapic, antiproliferative abilities in suppressing cancer proliferation in humans;[29][30] however, it has been deemed suitable for cat cancer treatment.[31]

Nonetheless, feline cancer research into this, as well as other treatment options, remains an ongoing process.

See also

References

Notes
  1. 1 2 3 "Feline Cancer Resources". Retrieved 2012-03-22.
  2. 1 2 3 4 5 Eckstein, Sandy. "Cancer in Cats: Types, Symptoms, Prevention, and Treatment". WebMD. Retrieved 2012-03-22.
  3. 1 2 3 4 5 Wells, Virginia. "Feline Cancer: What are the Warning Signs?". Intelligent Content Corp. Retrieved 2012-03-22.
  4. ↑ "Cancer Diagnosis in Cats and Dogs". Pet Cancer Center. 2011-10-16. Retrieved 2012-03-22.
  5. 1 2 "LYMPHOMA IN CATS" (PDF). Southern California Veterinary Specialty Hospital. Retrieved 2012-03-22.
  6. ↑ "Skin Tumors in Cats: An Overview". Petwave. Retrieved 2012-03-22.
  7. 1 2 "Skin Cancer (tumors) in Cats and Dogs". Pet Cancer Center. 2011-10-16. Retrieved 2012-03-22.
  8. 1 2 "Mammary Gland (Breast) Cancer in Cats". Pet Cancer Center. 2011-10-16. Retrieved 2012-03-22.
  9. 1 2 "Stomach (Gastric) Cancer in Cats and Dogs". Pet Cancer Center. 2011-10-16. Retrieved 2012-03-22.
  10. 1 2 Pinney, C (2004). A Complete Home Veterinary Guide, p. 663-683. McGraw Hill, United States.
  11. 1 2 3 4 Hardy, W.D. (1976). "Prevention of the contagious spread of feline leukaemia virus and the development of leukaemia in pet cats". Nature. 263: 326–328. doi:10.1038/263326a0.
  12. 1 2 3 AScribe News. (2001). "Cats and Dogs Also Face Skin Cancer Danger From Sun." Chicago Tribune. Retrieved March 23.
  13. ↑ Syufy, Franny. (2012). "Care of a Pregnant Cat." Cats. Retrieved March 23.
  14. ↑ "Sunburn (Solar Dermatitis) in Cats – Symptoms, Treatments and How to Avoid Solar Dermatitis in Cats. Cat World. (2012). Retrieved March 23.
  15. ↑ Liz-Cat. (2010). "3 Ways to Help Your Cat Prevent Cancer Now." Natural Cat Care Blog. Retrieved March 23.
  16. ↑ Nelson, Brenda. (2008). How to Prevent Cancer in Cats. Knoji. Retrieved on March 22, 2012.
  17. ↑ "The Original Internet Guide to Feline Diabetes". Retrieved 25 March 2012.
  18. ↑ Daristotle, L (11 January 1992). "AIDS Research: from apes to cats". Journal of the American Veterinary Medical Association. 201 (9): 1334.
  19. ↑ Rand, Michael. "The Cat in Biomedical Research". Retrieved 25 March 2012.
  20. ↑ Schiff, Laurie. "Why Cat Fanciers Support Animal WELFARE, not Animal RIGHTS". Retrieved 29 March 2012.
  21. ↑ Sample, Ian (11 November 2008). "Oxford University opens controversial animal research laboratory". The Guardian. Retrieved 25 March 2012.
  22. ↑ "How Animals End Up in Laboratories". People for the Ethical Treatment of Animals.
  23. ↑ "MU Study Finds Risk Factors for Cat Cancer, Could Have Implications for Human Cancer Prevention and Treatments". MU News Bureau. 28 September 2011. Retrieved 25 March 2012.
  24. ↑ "Common Parasite Potentially increases risk of brain cancers". 28 July 2011. Retrieved 25 March 2012.
  25. ↑ "Controversial Cancer Stem Cells Offer New Direction For Treatment". Science Daily. 25 June 2009. Retrieved 26 March 2012.
  26. ↑ Pang, Lisa; Argyle (February 2009). "Davus". BBA – Molecular Basis of Disease. 1792: 380–391. doi:10.1016/j.bbadis.2009.02.010.
  27. ↑ "Cats & dogs needed for cancer, IBD treatment studies". Today@Colorado. 5 August 2009. Retrieved 29 March 2012.
  28. ↑ "Cat's claw". American Cancer Society. Retrieved 29 March 2012.
  29. ↑ Riva, L.; et al. (July–August 2001). "The antiproliferative effects of Uncaria tomentosa extracts and fractions on the growth of breast cancer cell line". Anticancer Research. 21 (4A): 2457–61.
  30. ↑ Spellman, K; et al. (June 2006). ",Modulation of cytokine expression by traditional medicines: a review of herba immunomodulators". Alternative Medicine Review. 11 (2): 128–50.
  31. ↑ Messonnier, Shaun (2006). The Natural Vet's Guide to Preventing and Treating Cancer in Dogs. Novato, CA: New World Library.
Bibliography

External links

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