Cancer “young” and “old”
US veterinarians evaluated risk factors for cancer in younger dogs in a large study. The study was published in the journal PLOS ONE.
Scientists have found that non-neutered and purebred dogs weighing more than 75 kilograms get cancer several years earlier than others. Other risk factors were male sex and breed of animal. The study found that Bichon Frize dogs lived the longest without cancer, and Mastiffs, St. It showed that Bernards, Great Danes and Bulldogs have the “youngest” cancer.
“It should be emphasized that the article does not mention a higher incidence of cancer in different races. Scientists focused on the exact age of emergence. The authors’ point of view is that some animals should be examined early,” says veterinary oncologist Dmitry Trofimtsov.
For this reason, regular doctor visits are essential, even for young and apparently healthy dogs. As Trofimtsov noted, many veterinary clinics have analogues of clinical examinations in humans.
“Up to the age of ten, we recommend taking the animal to the doctor once a year: vaccinations, blood tests, examinations and abdominal ultrasounds. Sometimes a lung x-ray is taken, but this method is not informative for detecting cancer or metastases. After ten years, the animal needs to be examined twice a year,” said veterinary oncologist Alexander Kablukov.
racial influence
Previously, other cancer studies in dogs have shown that breeds differ not only in the age at which cancer is detected, but also in their propensity to develop tumors. One reason for this is defects in the p53 protein. A version of this protein has been found in most mammals whose genomes have been adequately studied. Normally, p53 regulates the cell cycle by controlling the activity of several genes and prevents the development of malignant tumors.
“There are breeds with dangerous mutations in the TP53 gene (which regulates the production of the p53 protein), for example, various retriever breeds and Bernese Mountain Dogs. These dogs are often prone to developing malignant tumors with a genetic risk of up to 51%.
Scottish Terriers have a high risk of bladder cancer. German boxers, Dobermans and Rottweilers are prone to lymphomas, pugs are prone to mastocytomas, and German shepherds are prone to hemangiosarcomas, i.e. tumors of vascular tissue. Giant breeds have a high risk of osteosarcoma affecting the bones.
Therefore, if you have a Great Dane lame, any lameness should be considered a manifestation of osteosarcoma until proven otherwise, Kablukov explained, “Cancer in a dog can be suspected by reducing the animal’s body weight and fatigue. The most important sign is not weight loss, but reduction in muscle mass. However, this symptom usually occurs in the later stages, when it is impossible to help. Therefore, if you notice a decrease in a dog’s body weight, be sure to show the animal to a doctor.
vaccine induced sarcoma, virus induced skin cancer
In addition to the risk factors listed in the article, exposure to tobacco smoke and obesity can also increase the risk of cancer in dogs, Trofimtsov said.
“Research has also shown that cancer in dogs is not associated with any particular food. It does not matter whether the dog is fed natural or industrial food. Vaccination alone also does not affect anything. Cats have occasionally been shown to develop sarcoma at the site of vaccination. However, this is approximately out of a hundred thousand cases. it happens very rarely in three,” he said.
The doctor added that because of the risk of sarcoma, some vaccines are recommended to be administered not to the shoulders, but to the crease of the knee or the base of the tail: they are easier to treat that way. Concerns about sarcoma should not cause owners to refuse the vaccine. Also, some viruses on their own can cause cancer or weaken the animal’s immune system, destroying cancerous tumors that appear constantly, almost every day.
“Dogs have certain types of papillomaviruses that increase the risk of certain types of cancer, such as squamous cell skin cancer. The virus is transmitted from mother to dog, as well as through saliva when sharing bowls and toys. Humans also have papillomaviruses, including oncogenic ones, but dogs and humans also have papillomaviruses. between them is impossible: infections are species-specific, “explained Trofimtsov.
drug phobia
As Kablukov points out, owners often let a tumor develop, because they are told: “It’s just a bump in the animal, maybe it will clear up, let’s observe for half a year.” But for a human and a dog, six months are different periods. If any formation is felt under the skin, it should be examined in more detail.
“Subcutaneous lesions in dogs often appear late in life. You do not need to be afraid of the operation to remove them. Old age is not a contraindication for anesthesia. Most tolerate it normally, anesthetists take all the risks into account. If a tumor is suspected, we do a biopsy of the formation, ”explained Kablukov .
Although there is currently no reliable animal cancer screening program, this may change in the future.
In both humans and animals, tumors secrete specific substances that can be found in the blood or urine. In some cases these may be DNA or RNA residues, in others they may be special proteins or other molecules.
The diagnostic method for such substances is called liquid biopsy. Its main advantage is low invasiveness (blood or urine test is sufficient) and the ability to accurately determine the type of tumor. Veterinarians noted that until now such diagnostics were not routinely used.
As the scientists point out in the article, liquid biopsy may become the main method for diagnosing certain types of cancer in dogs in the future. You should understand that the method is not universal. Each tumor secretes a specific type of protein, so a test can identify a type of cancer. At the same time, each tumor needs its own laboratory kits, which are not yet available. In America and Europe, a kind of analysis that can be called a liquid biopsy is already being done: a urine test for B-Raf protein to diagnose bladder cancer, ”said Trofimtsov.