{{Short description|none}} <!-- "none" is a legitimate description when the title is already adequate; see [[WP:SDNONE]] --> [[File:Cancer_beagle.jpg|thumb|A 10-year-old female beagle with [[oral cancer]]]] [[Cancer]] is the leading cause of death in [[dog|dogs]].<ref name=":1" /> It is estimated that 1 in 3 domestic dogs will develop cancer, which is the same incidence of cancer among humans.<ref name=":0" /> Dogs can develop a variety of cancers and most are very similar to those found in humans. Dogs can develop [[carcinoma]]s of epithelial cells and organs, [[Soft-tissue sarcoma|sarcomas]] of connective tissues and bones, and [[lymphoma]]s or [[leukemia]]s of the circulatory system. Selective breeding of dogs has led certain pure-bred breeds to be at high-risk for specific kinds of cancer.<ref name=":1" />
[[Veterinary oncology]] is the medical study of cancer in animals, and can be diagnosed and treated by specialized veterinarians called veterinary oncologists.
==Causes== Cancer is a complex, multifactorial disease.<ref name=":0" /> Carcinogenesis is linked with DNA mutations, chromosomal translocations, dysfunctional proteins, and aberrant cell cycle regulators.<ref name=":1" /> Cancer alters the DNA of cells and the mutated genetic material is passed on to daughter cells, resulting in [[neoplasm]]s.<ref name=":0" /> The mutated DNA affects genes involved with the [[Cell cycle checkpoint|cell cycle]], classified as either [[oncogene]]s or [[tumor suppressor gene]]s.<ref name=":0" /> Oncogenes are responsible for cell proliferation and differentiation.<ref name=":0" /> Oncogenes responsible for cell growth are overexpressed in cancerous cells. Tumor suppressor genes prevent cells with erroneous cell cycles from replicating.<ref name=":0" /> Cancer cells ignore cell cycle regulators that control cell growth, division, and death.<ref name=":0" />
The histology of spontaneous tumorigenesis in canines is attributed to the multiplicity and complexity of the disease. The heterogeneity of its development encompasses inherited, epigenetic, and environmental factors.<ref name=":0" /><ref name="ASPCA" />
The [[selective breeding]] techniques used with domestic dogs causes certain breeds to be at high risk for specific cancers. Selection for specific phenotypes in dog breeding causes long-range [[linkage disequilibrium]] in their DNA.<ref name=":1" /> Certain areas of alleles have the tendency to separate less frequently than normal random segregation, which leads to long ranges of repeated DNA sequences. These repeated sequences caused by decreased genetic diversity within breeds, can lead to a high prevalence of certain diseases and especially cancer in breeds. It is believed that the breeding and inbreeding of domesticated canines for specific traits has significantly decreased nucleotide diversity in many pedigree dogs, making certain varieties of canines more susceptible to developing cancer.<ref>{{cite journal |last1=Dobson |first1=Jane |title=Breed-Predispositions to Cancer in Pedigree Dogs |journal=ISRN Veterinary Science |year=2013 |volume=2013 |article-number=941275 |doi=10.1155/2013/941275 |pmid=23738139 |pmc=3658424 |doi-access=free }}</ref>
==Symptoms== Symptoms of cancer in dogs may include:
*Lumps (which are not always malignant, but should always be examined by a vet) *Swelling *Persistent sores *Abnormal discharge from any part of the body *Bad breath *Listlessness/lethargy *Rapid, often unexplained weight loss *Sudden lameness *Offensive odor *Black, tarry stools (a symptom of ulcers, which can be caused by mast cell tumors) *Decrease in appetite or loss thereof *Difficulty breathing, urinating or defecating<ref name="ASPCA">{{cite web|url=http://www.aspca.org/pet-care/dog-care/cancer|title=Pet Care Cancer|website=ASPCA|archive-url=https://web.archive.org/web/20141213014540/http://www.aspca.org/pet-care/dog-care/cancer|archive-date=2014-12-13}}</ref>
== Types of cancer == Dogs can develop many of the same types of cancer as humans. Many canine cancers are described with the same terminology and use the same classification systems as human cancers.<ref name=":1" /> * Mast cell tumors are the most common type of [[Skin cancer in cats and dogs|skin cancer in canines]].<ref name=":1" /> * Lymphoma * Prostate cancer * Brain cancer [[Hemangiosarcoma]] is a type of cancer that is common in dogs.<ref>{{Cite journal |last1=De Nardi |first1=Andrigo Barboza |last2=de Oliveira Massoco Salles Gomes |first2=Cristina |last3=Fonseca-Alves |first3=Carlos Eduardo |last4=de Paiva |first4=Felipe Noleto |last5=Linhares |first5=Laís Calazans Menescal |last6=Carra |first6=Gabriel João Unger |last7=dos Santos Horta |first7=Rodrigo |last8=Ruiz Sueiro |first8=Felipe Augusto |last9=Jark |first9=Paulo Cesar |last10=Nishiya |first10=Adriana Tomoko |last11=de Carvalho Vasconcellos |first11=Carmen Helena |last12=Ubukata |first12=Rodrigo |last13=Batschinski |first13=Karen |last14=Sobral |first14=Renata Afonso |last15=Fernandes |first15=Simone Crestoni |date=2023-03-29 |title=Diagnosis, Prognosis, and Treatment of Canine Hemangiosarcoma: A Review Based on a Consensus Organized by the Brazilian Association of Veterinary Oncology, ABROVET |journal=Cancers |volume=15 |issue=7 |page=2025 |doi=10.3390/cancers15072025 |doi-access=free |issn=2072-6694 |pmid=37046686|pmc=10093745 }}</ref> Hemangiosarcomas form from the cells lining blood vessels (endothelial cells) and can occur all over the body. These tumors can develop on the skin, subcutaneously, or on a blood vessel within an organ and are highly malignant. The tumors are most fatal when they rupture, causing the dog to suffer from severe loss of blood, or [[hypovolemia]].<ref name=":2">{{cite journal|pmid=25634078|year=2015|last1=Pang|first1=L. Y.|title=The evolving cancer stem cell paradigm: Implications in veterinary oncology|journal=The Veterinary Journal|volume=205|issue=2|pages=154–60|last2=Argyle|first2=D. J.|doi=10.1016/j.tvjl.2014.12.029}}</ref>
Dogs are one of three mammalian species that are known to suffer from a transmissible cancer.<ref name=":4">{{Cite journal|last=Ganguly|first=B|year=2013|title=Canine transmissible venereal tumour: a review|journal=Veterinary and Comparative Oncology|volume=14|issue=1|pages=1–12|pmid=23981098|doi=10.1111/vco.12060}}</ref> [[Canine transmissible venereal tumor]] (CTVT) is species specific and highly contagious.<ref name=":4" /> The cancerous cell lines are transmitted between individuals that are in close contact with each other through acts of intercourse, biting, scratching, or licking.<ref name=":4" /> The cancer is prevalent in populations of stray dogs or environments of uncontrolled copulation.<ref name=":4" /> The tumors occur around the area of external genitalia and can grow up to 15 cm in area.<ref name=":4" /> Canine transmissible venereal tumors can often be infected, ulcerated, and hemorrhagic.<ref name=":4" />
==Susceptibility== Cancer prevalence in dogs increases with age and certain breeds are more susceptible to specific kinds of cancers. Millions of dogs develop spontaneous tumors each year.<ref name=":1">{{Cite journal|last1=Gardner|first1=Heather L.|last2=Fenger|first2=Joelle M.|last3=London|first3=Cheryl A.|year=2016|title=Dogs as a Model for Cancer|journal=Annual Review of Animal Biosciences|volume=4|issue=1|pages=199–222|doi=10.1146/annurev-animal-022114-110911|pmid=26566160|pmc=6314649}}</ref> [[Boxer (dog)|Boxers]], [[Boston Terrier]]s and [[Golden Retriever]]s are among the breeds that most commonly develop [[mast cell tumor]]s. Large and giant breeds, like [[Great Dane]]s, [[Rottweiler]]s, [[Greyhound]] and [[St. Bernard (dog)|Saint Bernards]], are much more likely to develop [[bone cancer]] than smaller breeds.<ref name=":1" /> Lymphoma occurs at increased rates in Bernese Mountain dogs, bulldogs, and boxers.<ref name=":1" /> It is important for the owner to be familiar with the diseases to which their specific breed of dog might have a breed predisposition.<ref name=ASPCA/>
A study of 144 female dogs found that dogs eating higher amounts of [[red meat]], especially [[beef]] and [[pork]], were more likely to get [[Mammary tumor|mammary cancer]].<ref>{{Cite journal|last1=Alenza|first1=Dolores Pérez|last2=Rutteman|first2=Gerard R.|last3=Peña|first3=Laura|last4=Beynen|first4=Anton C.|last5=Cuesta|first5=Pedro|date=1998|title=Relation between Habitual Diet and Canine Mammary Tumors in a Case-Control Study|journal=[[Journal of Veterinary Internal Medicine]]|language=en|volume=12|issue=3|pages=132–139|doi=10.1111/j.1939-1676.1998.tb02108.x|pmid=9595373|issn=1939-1676|quote=The intake of homemade meals (compared to that of commercial foods) was also significantly related to a higher incidence of tumors and dysplasias. Other significant risk factors were a high intake of red meat, especially beef and pork (...) We found mammary tumor risk to be positively associated with the intake of red meat and negatively associated with the intake of poultry meat. Particularly, the intake of red meat emerged as an independent factor associated with the risk in the multivariate analysis. Epidemiologic studies have revealed an association between human breast cancer and the consumption of beef and pork and meat; and sausage, eggs, and meat. However, we have not found an association between consumption of vegetables and fruits and mammary tumor development. Higher consumption of vegetables and fruits is associated, although not universally, with a decreased risk of cancer at most sites in humans, especially epithelial cancers of the alimentary and respiratory tracts. The intake of crude fiber, carotene and vitamin C, and fruits and vegetables has been inversely associated with breast cancer risk|doi-access=free}}</ref><ref>{{Cite web|last=Attwood|first=Diana|title=Infopet - Dogs and diet|url=https://www.infopet.co.uk/index.php/18-animal-care-and-behaviour/dogs/29-dogs-and-diet|access-date=2021-10-21|website=www.infopet.co.uk|language=en-gb}}</ref>
Spayed female dogs are less likely to develop cancers affecting the mammary glands, ovaries, and other reproductive organs.<ref>{{Cite book|author=Morrison, Wallace B.|title=Cancer in Dogs and Cats (1st ed.)|publisher=Williams and Wilkins|year=1998|isbn=978-0-683-06105-5}}</ref>{{page needed|date=May 2021}} For males, [[Dog#Neutering|neutering]] decreases the risk of [[prostate cancer]] ,<ref>{{Cite web|title=Spay and Neuter Your Pets Good for you, your pet, and the community|url=https://www.brown.edu/Research/Colwill_Lab/CBP/spaynueter.htm#:~:text=Neutering%20your%20male%20dog%20or,by%20fighting%20are%20greatly%20reduced.}}</ref> but can increase the risk of [[osteosarcoma]] and [[hemangiosarcoma]] in either sex.<ref>{{Cite journal|author=Root-Kustritz MV |title=Determining the optimal age for gonadectomy of dogs and cats |journal=JAVMA |volume=231 |issue=#11 |pages=1665–1675 |date=Dec 2007|doi=10.2460/javma.231.11.1665 |pmid=18052800 |s2cid=4651194 |issn=0003-1488|doi-access=free }}</ref>
==Treatment== 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 increased 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.<ref name=":0">{{Cite journal|doi=10.1016/j.tvjl.2016.03.009|pmid=27240913|title=Veterinary oncology: Biology, big data and precision medicine|journal=The Veterinary Journal|volume=213|pages=38–45|year=2016|last1=Pang|first1=Lisa Y.|last2=Argyle|first2=David J.|url=https://www.pure.ed.ac.uk/ws/files/24558649/YTVJL_S_16_00233.pdf|hdl=20.500.11820/0671e750-5fde-4e2e-8951-4d5c78c1a2ce|hdl-access=free}}</ref> Cancer-targeting drugs most commonly function to inhibit excessive cell proliferation by attacking the replicating cells.<ref name=":2" />
There is one canine tumor vaccine approved by the [[United States Department of Agriculture|USDA]], for preventing canine melanoma.<ref name=":3">{{Cite journal|pmid=26545847|year=2016|last1=Regan|first1=D|title=Cancer immunotherapy in veterinary medicine: Current options and new developments|journal=The Veterinary Journal|volume=207|pages=20–8|last2=Guth|first2=A|last3=Coy|first3=J|last4=Dow|first4=S|doi=10.1016/j.tvjl.2015.10.008}}</ref> The Oncept vaccine activates [[T cell|T-cell]] responses and antibodies against tumor-specific [[tyrosinase]] proteins.<ref name=":3" /> 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.<ref name=":3" />
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.<ref name=":0" />
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.<ref name=ASPCA/>
==Prognosis==
According to Blue Cross, pet owners can expect for their pet to live about 12 months with current treatments. If the owner opts for palliative care instead of treatment, the dog will live about 3 months, although if the tumor is partially removed this can be extended. The survival time may be longer in large dogs, and the cure rate is 20%. If a tumor is completely removed, usually the pet will receive small doses of radiation in hopes of preventing recurrence. The survival rates are: 1 year: 59%, 3 year: 40%, 5 year: 13%.<ref>{{Cite web|url=https://www.bluecross.org.uk/pet-advice/coping-cancer-dogs|title = Cancer in Dogs | Symptoms and treatment}}</ref>
== See also ==
* [[Puppy Up Foundation]]
==References== {{reflist}}
==External links== *[http://www.peteducation.com/category_summary.cfm?cls=2&cat=1638 Cancer in Dogs: Symptoms, Diagnosis and Treatment] from Pet Education *[http://klasiquegoldens.com/library/cancer.pdf] from Understanding Cancer in Golden Retrievers
[[Category:Cancer in dogs| ]]