| The 10 Early Warning Signs of Cancer ( From the American Veterinary Medical Association)
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| Cancer cells develop because of damage to DNA. This substance is in every cell and directs all activities. Most of the time when DNA becomes damaged the body is able to repair it. In cancer cells, the damaged DNA is not repaired. Dogs can inherit damaged DNA, which accounts for inherited cancers. More often, though, a dog's DNA becomes damaged by exposure to something in the environment, like smoke, pesticides or other carcinogens. Cancer frequently forms as a tumor. Some cancers do not form tumors. Instead, these cancer cells involve the blood and blood-forming organs and circulate through other tissues where they grow. Often, cancer cells travel to other parts of the body where they begin to grow and replace normal tissue. This process is called metastasis. Regardless of where a cancer may spread, however, it is always named for the place it began. For instance, breast cancer that spreads to the liver is still called breast cancer, not liver cancer. Not all tumors are cancerous. Benign (noncancerous) tumors do not spread (metastasize) to other parts of the body and, with very rare exceptions, are not life threatening. Different types of cancer can behave very differently. For example, bone cancer and breast cancer are very different diseases. They grow at different rates and respond to different treatments. That is why dogs with cancer need treatment that is aimed at their particular kind of cancer. Cancer rates increase in dogs with age. It is the leading cause of death in dogs over 10 years. Diagnosis If cancer is suspected in your dog, a veterinarian may order x-rays, blood tests, ultrasounds. A biopsy (the removal of a piece of tissue) is frequently performed for confirmation that cancer exists and to determine the level of severity from benign to aggressively malignant (called grading). Prevention We do not know how dogs get cancer most of the time. There are many types of cancer and many possible causes of cancer (chemicals in our environment, sun exposure, assorted viruses and infections). There are important genetic factors as well. Feeding your dog a healthy diet and keeping them away from known carcinogens will help. Spaying or neutering your dog will also reduce their risk for developing certain cancers. Treatment Each diagnosis of cancer requires individual care and treatment planning. Conventional treatment may include a combination of treatment therapies such as surgery, chemotherapy, radiation, cryosurgery (freezing), hyperthermia (heating) or immunotherapy. Complementary and alternative veterinary medicine (CAVM) therapies include acupuncture, behavior modification, homeopathy, herbal medicine, mega-nutrient augmentation therapy, nutritional therapy and chiropractic therapy. (Click on our Treatments page for further information on therapies). Once diagnosed, your veterinarian will discuss the best treatment option(s) for your dog. In some instances, your veterinarian may refer you to a board-certified oncologist (cancer specialist) depending upon the recommended course of treatment. It never hurts to get a second opinion and to research clinical trials for which you dog may be eligible. Prognosis Treatment success depends upon the type and extent of the cancer, as well as the aggressiveness of therapy. Some cancers can be cured and almost all patients can be helped to some degree. Another critical point is to understand exactly what is meant when data on efficacy of treatment is presented. Useful terms include: Median - this is used in the context of survival, a median survival of three months means that 50% of the animals are alive at three months, but 50% have died. It does not give you any information of the range of survival of individuals from within the group. For example, individual animals may have survived for only a day to several years. A median survival is very useful to allow comparison between different types of treatment. Survival means just that: how long an animal stayed alive, usually from time of diagnosis, but it could also mean from time of treatment, or from time the owner first noticed signs of a problem. It does not give you any information on what the animal's quality of life was during that time. Progression free survival is the time the animal survived without progression of the clinical signs. This gives you a better idea of the quality of life. Common Cancer Terms Cancer: any malignant, cellular tumor; cancers are divided into two broad categories of carcinoma and sarcomas. Neoplasm: an abnormal new growth of tissue in animals or plants; a tumor Tumor: 1.) a swelling; a cardinal sign of inflammation. 2.) neoplasm: a new growth of tissue in which cell multiplication is uncontrolled and progressive. Benign tumor: one lacking the properties of invasion and metastasis and showing a lesser degree of abnormal cellularity than do malignant tumors. These are usually surrounded by a fibrous capsule. Malignant tumor: has the properties of invasion and metastasis and displays cells with widely varying characteristics Carcinoma: a malignant growth made up of epithelial cells tending to infiltrate surrounding tissues and gives rise to metastases. Sarcoma: a malignant tumor originating from connective tissue or blood or lymphatic tissues. Metastasize: spread throughout the body, of cancer cells Growth: can refer to any kind of an abnormal increase in size of tissue Lump: can be a growth or fluid filled cyst or any structure raising above the normal surface of a tissue plane. ________________________________________________________________________ Cancer in dogs: mechanism and cause.... by Dr. Larry Thornburg, University of Missouri From normal cell to cancer cell. All organs in your dog are composed of cells. Cells are tiny units that can only be seen with a microscope. Thousands of cells make up each organ in your dog's body. In general, all cells in all organs are alike (in the same manner one can say that all cars are alike). All cells digest food using organelles (literally "tiny organs") called lysosomes. The energy for all cells is supplied by organelles called mitochondria. All cells manufacture proteins using organelles called ribosomes. Each and every cell in your dog's body contains exactly the same DNA (genes, chromosomes). And, the DNA that is in each cell is unique to your dog, different in some ways even from that of his/her littermates. The nucleus of every cell contains between 60,000 and 100,000 genes. Among those 60,000-plus genes are approximately 100 genes that control cell division. Think about the union of the egg and the sperm giving rise to a single cell. That single cell and the many generations of daughter cells, divide thousands of times over 63 days to produce the normal puppy with bones, muscles, skin, hair, heart, kidneys for example. Over the next several weeks to months those generations of cells composing the puppy must divide thousands of more times in order for the puppy to grow into the adult dog. The majority of cells never divide again once adult size is reached. Only a few cell types such as bone marrow cells, skin cells and cells of the intestines continue to divide throughout the lifetime of your dog. More than 50 years of scientific research by thousands of scientists worldwide and billions of dollars have been spent trying to understand cancer. The main question that scientists are trying to answer is, "How do cells know when to divide and when to stop dividing?" "Cancer" is the disease that occurs when the normal control genes in a cell fail and that cell is released to divide relentlessly. Cells of the bone, skin, liver, blood vessels, heart, brain, any cell in your dog's body can become transformed into a cancer cell. When cells divide out of control the accumulation of more and more cancerous daughter cells results in crowding out of the normal cells and, eventually, failure of the affected organ. Accumulation of cancerous daughter cells can result in the appearance of an enlarging nodule on the bone or in the skin, for example. In addition, the cancerous daughter cells may have the capacity to reach distant organs (metastasize) by traveling in the blood. Once the mobile cancer cells reach a distant organ, the relentless cell division also causes failure of that organ (or those organs). What are "cancer genes"? The nucleus of each cell contains DNA (short for DeoxyriboNucleic Acid). DNA is organized into long structures termed chromosomes. In dogs there are 78 chromosomes. As opposed to your dog, you have 46 chromosomes. Each one of your individual chromosomes is longer that those of your dog. However, you and your dog have approximately the same total quantity of DNA. Genes are arranged along the chromosomes exactly like beads on a necklace. Those 78 chromosomes of your dog contain 60,000 to 100,000 genes. Those 60,000 to 100,000 genes control every activity that every cell in every organ performs, including cell division. Some of the 100 genes that control cell division are comparable to the car accelerator and these genes cause cells to divide. However, there is another group of genes that is comparable to the brakes of the car and these genes prevent cells from dividing. Each cell maintains a careful balance of activity between the two groups of control genes. This careful balance allows all cells to divide during development of the puppy. But, that delicate balance changes in the adult dog to prevent the majority of cells from dividing, while allowing controlled division in cells such as blood producing cells. When cell-division-control genes becomes mutated (the DNA changes in chemical structure), the balance is lost forever and uncontrolled cell division (cancer) results. These two groups of genes that control cell division are called "cancer genes." All cancers are the result of mutations in one or more of the approximately 100 genes that control cell division. What causes the mutations in the cancer genes? Each day of your dog's life all of the genes of each cell are subjected to a barrage of insults that have the potential to cause a mutation. Toxic chemicals can cause a mutation in DNA. One category of toxic chemicals comes from within the cell. These toxic chemicals are normal products of daily chemical activities within each cell. For the most part, cells have developed mechanisms for detoxifying these waste products. However, some of these toxic waste products escape the protective mechanisms of the cell and attack the cell's DNA. Another category of toxic chemicals are components of the normal diet. Every diet contains plant matter. All plants have developed various chemical mechanisms to evade being eaten by their natural predators: insects, bacteria, fungus and viruses. The chemicals that are toxic to the natural predators of plants are also toxic to the living cells of your dog in many instances. Some of these naturally occurring chemicals can cause mutations in the DNA. A third category of toxic chemicals is the man-made chemicals. There is a long list of man-made chemicals that are known to cause mutations in the DNA of cells and result in cancer. Viruses can cause a mutation in a gene. However, there are very few viruses that have been proven to cause cancer in dogs, and at this time it does not appear that viruses are a significant cause of cancer in dogs. Irradiation (the sun's rays) can cause cancer. Cancer caused by irradiation is uncommon in domestic animals except those individuals without pigmentation in their skin. Lifetime exposure to the sun can cause cancer on the white ears or white face of dogs. All of these above are known as "acquired cancer." Inherited cancer is somewhat different. All genes are paired (two copies of each gene) within every cell. One copy of the gene comes from the dam and one copy of the gene comes from the sire. With many of the 60,000-plus genes there is not a substantial consequence when one gene of the pair is mutated because the cell has the other (normal) copy to carry on normal function. The two groups of cancer genes (the "accelerator" genes versus the "brake" genes) are somewhat different from each other. It generally requires only one copy of an "accelerator" gene to be mutated for cancer to occur. However, both copies of a "brake" gene must be mutated for cancer to occur. When a puppy inherits one mutated copy of a "brake" gene from the dam or the sire, every cell in each organ has only one normal copy to carry out the control of cell division. That puppy has an increased risk of developing cancer relative to dogs with two normal copies of the "brake" gene. If the dog with only one normal copy of the gene suffers a single chemical insult, the affected cell will lose control of cell division and it will become a cancer cell. Dogs do not "inherit" cancer per se. Dogs (and people) inherit a "susceptibility" to develop cancer. That is, the dog that inherits one abnormal copy of a "brake" gene is more likely to develop cancer in his/her lifetime than is a littermate with two normal copies of the same "brake" gene. Genetic testing attempts to determine if a particular dog inherited (and could consequently pass to the offspring) one abnormal copy of a cancer gene. Why is treatment of cancer so difficult? Generally, there are three methods by which cancer can be treated. Surgery is a good choice for treatment if the cancer is localized to a single area and the veterinarian has the opportunity to completely remove the cancer. However, some cancers, although localized, occur in areas that are not amenable to surgery (in the wall of the heart for example). Likewise, another cancer may have occurred originally in the skin, but has now spread to several different areas of the lungs. Surgery would not provide a cure for this dog. Chemotherapy is a second choice for treatment of cancer. As you can see from the information presented above, cancer is simply a normal process (ie, cell division) that is out of control. Cancer cells are identical to normal cells in every way except the control of cell division (cancer cells have lost the control of cell division). Chemotherapeutic agents are toxic chemicals that are used to kill the cancer cells. However, since all cells in the body are undergoing the exact same living processes, all chemotherapeutic agents kill normal cells as well as cancer cells. This is the reason why some dogs (and some people) get very sick during the chemotherapy. The drugs and the dose of those drugs that are used for chemotherapy are a delicate balance between killing the cancer cells and killing the normal cells of the body. Radiation is the third mode of cancer therapy. Radiation has the potential to kill any cell in the body. Again, the idea of radiation therapy for cancer is to localize the destructive beam to the cancer, sparing the normal cells. This can be very successful when the cancer is a solitary nodule and the radiation beam can be focused on the cancer. However, when cancer is widespread (metastatic cancer) it is usually not possible to kill only the cancer cells and radiation is rarely a treatment under such circumstances. |
| Click here for a dictionary of cancer related terms from the National Cancer Institute Cancer Dictionary |
| Information and Inspiration when you need it most |
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| What is Cancer? Dog cancer, like human cancer, is the uncontrolled growth of cells on or within the body. Although there are many types of cancer, they all start because of out-of-control growth of abnormal cells. Normal body cells grow, divide, and die in an orderly fashion. During the early years of a dog's life, normal cells divide more rapidly until the dog becomes an adult. After that, cells in most parts of the body divide only to replace worn-out or dying cells and to repair injuries. Because cancer cells continue to grow and divide, they are different from normal cells. Instead of dying, they outlive normal cells and continue to form new abnormal cells. |
Vaccinations Many veterinarians will recommend that dogs with cancer not be vaccinated. Vaccinations can stress your dog's immune system and may counteract any positive effects of your treatment program. Some healthy dogs have developed cancer and other serious conditions as a result of vaccinations. Are we over vaccinating our dogs? |
| Cancer Facts Cancer is the number 1 concern of pet owners and the number 1 natural cause of death in older dogs. The most common forms of cancer are: • breast • skin • bone • connective tissue • oral • lymphoma Known and suspected carcinogens (cancer causing agents) include: • herbicides • insecticides • second-hand smoke • radiation exposure • certain viruses • genes/improper breeding • over/unnecessary vaccinations •chemical additives and preservatives in food |
When your dog is believed to be ill, your vet may order
various lab tests to try to determine what is wrong.
The tests most often done are Hematology and Blood
Chemistry. The Hematology values indicate the
numbers of the different kinds of cells and the amount
of hemoglobin in the blood, while the Blood Chemistry
tells you the amounts of the different chemical
substances dissolved in the liquid component of
blood, the plasma. Since there are differences in
normal values between breeds of dogs, and even
between individuals, and because different
laboratories will show on the lab report slightly
different normal ranges (depending on which specific
tests that lab uses), it is important that you find out
what is normal for your dog, when it is in good health
so that if certain values change, they are recognized
as different from your dog’s normal situation. In this
way your vet will detect any problems early on, so that
they can be treated early when treatment is more likely
to be effective.
There are additional lab tests, such as urinalysis, and
specialized blood tests aimed at examining such
components as hormones, antibodies, and clotting
factors. These may be ordered if there is a suspicion
of problems that the vet thinks might be glandular or
immune in nature or related to improper blood
clotting. When a problem with an internal organ is
suspected, your vet may order a specific “profile” to
check the particular values associated with the organ
thought to be having trouble (“hepatic profile” to check
liver function, “renal profile” to check kidney function,
“pancreatic profile” to check the pancreas).
Below are some of the commonly performed lab tests,
and the range of normal values (in USA units; Source:
Merck Veterinary Manual). If your dog’s result on a test
falls outside the normal range, the lab will flag that on
the report as either High or Low.
The normal body temperature of a dog is 101 to 102.5.
HEMATOLOGY
CBC (Complete Blood Count)
RBC (red blood cell count) 5.5 - 8.5 cells X 106/ml
Vitamin B-12). High RBC suggests dehydration.
Vitamin B-12). High RBC suggests dehydration.
WBC (white blood cell count) 6 - 17 cells X 103/ml
Low WBC count suggests major virus infection,
certain drug or chemical toxicity. High WBC caused by
bacterial infections, stress, malignancies of blood.
Hb or Hgb (Hemoglobin) 12 - 18 g/dL
Low Hgb caused by anemia, which can result from
bleeding, nutritional deficiencies, parasitic infections,
chronic diseases of liver, cancer. High levels seen
with dehydration.
Ht or Hct (Hematocrit; Packed Cell Volume) 37 -
55 % of whole blood by volume
Low in anemia resulting from hemorrhage, nutritional
deficiencies, parasites, chronic diseases. Elevated in
dehydration.
PL (or plts) (Platelets) 2 - 9 x 105/ml
Important one of several components of blood clotting
process. Decreased platelets put dog at risk of
bleeding, and results from hemorrhage, some
autoimmune disorders (lupus, hemolytic anemia),
depression of bone marrow, clotting within blood
vessels. Elevated platelets suggests cancer or can
result from injury to blood vessels or bone fracture.
DIFF (Differential white blood cell count ... relative
amounts of different types of WBC)
May be expressed as total numbers, or as % of total
WBC
Neutrophils 60 - 70%
Elevated in acute bacterial infections or extreme
stress.
Lymphocytes 12 - 30%
Reduced in initial stages of infections, or after steroid
use.
Monocytes 3 - 10%
Generally constant except in leukemia, when
increased.
Eosinophils 2 - 10%
Increased in parasitic infections and in allergies.
Decreased in prolonged stress.
BLOOD (SERUM) CHEMISTRY VALUES
ENZYMES
ALT Alanine aminotransferase; sometimes called
SGPT) 8.2 - 57.3 u/L
Elevated when liver is diseased
AMYL (Amylase) 269.5 - 1,462.4 u/L
Elevated in pancreatic or kidney disease
ALKP (Alkaline Phosphatase) 10.6 - 100.7 u/L
Elevated in diseases of liver or bones
AST (Aspartate transaminase; sometimes called
SGOT) 8.9 - 48.5 u/L
Elevated in liver disease
CK (Creatine kinase) 13.7 - 119.7 u/L
Elevation suggests heart disease
GGT (Gamma-glutamyl transferase) 1.0 - 9.7 u/L
Elevated in pancreatic disease, sometimes liver
disease
LDH (Lactic dehydrogenase) 24.1 - 219.2 u/L
Elevated in liver disease, heart disease
SDH (Sorbitol dehydrogenase) 3.1 - 7.6 u/L
Elevated in liver disease
Bicarbonate 18.1 - 224.5 mEq/L
Buffers the blood to maintain a normal acid/base
balance; can be affected by many things
Bilirubin 0.1 - 0.6 mg/dL
Elevated in liver disease, and in diseases where there
is abnormally fast breakdown of red blood cells
Calcium 8.7 - 11.8 mg/dL
Essential for bone formation, muscle activity, blood
clotting. Low levels seen in pancreatic injury,
underactive thyroid, eclampsia of pregnancy; elevated
levels seen in some tumors, kidney disease,
parathyroid gland disease.
Chloride 102.1 - 117.4 mEq/L
An electrolyte that must be in balance with sodium,
potassium, bicarbonate. Low chloride and electrolyte
imbalance in general can result from vomiting,
diarrhea; and can cause cardiac problems.
Cholesterol 115.6 - 253.7 mg/dL
High cholesterol not thought to be associated with
heart disease in dogs.Low levels seen with overactive
thyroid gland or faulty intestinal absorption of food.
Elevated levels seen in hypothyroidism, in liver, kidney,
and cardiovascular disease, and in diabetes and
stress.
Creatinine 0.5 - 1.6 mg/dL
Elevated creatinine suggests kidney disease. If
Creatinine is normal but BUN elevated, suggests early
or mild kidney disease. Increased creatinine and
increased BUN indicate longstanding renal disease,
especially if phosphorus also elevated.
Glucose 61.9 - 108.3 mg/dL
Elevated blood glucose suggests diabetes. Low
blood glucose seen in liver, pancreatic, and adrenal
gland disease.
Magnesium 1.7 - 2.7 mg/dL
Decreased in kidney, digestive tract, thyroid, and
adrenal disease, and with some drugs; low
magnesium has widespread consequences on heart,
muscles, metabolism.
Phosphorus 2.9 - 6.2 mg/dL
Low phosphorus seen in overactive parathyroid gland,
some malignancies, poor absorption of nutrients,
malnutrition. Elevated phosphorous seen with kidney
disease, underactive parathyroid gland, or kidney
failure (see BUN).
Potassium 3.8 - 5.6 mEq/L
One of the electrolytes (see Chloride)
Protein (Total) 5.5 - 7.5 g/dL
Increased in dehydration, cancers of blood and bone
marrow; decreased in malnutrition, liver and kidney
disease, bleeding. SPECIFIC proteins (Albumin,
Globulin) associated with more specific disorders.
Albumin 2.6 - 4.0 g/dL
Few albumin seen with chronic liver or kidney
disease, intestinal parasites; elevated albumin seen
with dehydration.
Globulin 2.1 - 3.7 g/dL
Low globulins indicate immune system malfunction,
infections. Elevated globulin seen with stress,
dehydration, allergies, blood diseases, liver disease,
heart disease, arthritis or diabetes.
Sodium 140.3 - 153.9 mEq/L
One of the electrolytes (see Chloride)
BUN (Urea Nitrogen) 8.8 - 25.9 mg/dL
If BUN is elevated but Creatinine is normal, suggests
early or mild kidney disease. If both BUN and
Creatinine are elevated, indicates longstanding renal
disease, especially if phosphorus is also elevated.
There are some interesting and promising results from research performed using Artemisinin on dogs with cancer. Please see our Herbal page for more details. Could it be the cure for some dogs? We hope so! |
Epidemiologic Studies of Risk Factors for Cancer in Pet Dogs Jennifer L. Kelsey,1 Antony S. Moore,2 and Lawrence T. Glickman3 In 1996, an estimated 52.9 million dogs were living in 31.6 percent of all households in the United States (1). Several epidemiologic studies have been undertaken to identify risk factors for cancer in pet dogs. This presentation reviews the literature on canine cancer epidemiology with a view towards exploring how these studies inform us about cancer causation in dogs and in humans. It focuses on observational studies of dogs living in their usual environments, and considers experimental studies in laboratory settings only to the extent that such studies shed light on the observational studies. It begins with a discussion of some methodological issues that make epidemiologic studies of cancer in dogs somewhat different from those in humans. Click here to continue reading: http://epirev.oxfordjournals.org/cgi/reprint/20/2/204 |