Pet Cancer Hard Facts
• Just as in people, the cause of cancer in our pets is largely unknown.
• Animals get cancer at the same rate as people.
• The American Kennel Club Canine Health Foundation has noted that 50% of dogs aged 10 or older will be affected by cancer. In other words, every other dog over 10 years of age will be affected with cancer. In fact, many dogs will have cancer before reaching 10 years of age.
Cancer in our pets strikes fear in our hearts, emits immediate images of suffering and pain, and produces feelings of loss. Our natural response is to panic and become depressed. After 40 years of practice, there is nothing I dread more than telling someone their pet may have cancer. While the word holds a discouraging diagnosis, it is important to remember the great advances which are currently happening in medicine. We should keep an open mind to treatment options and explore them. Granted, cancer treatment is not for every pet, but be encouraged and step back to evaluate options that may extend your pet’s life and produce quality time you may enjoy. Remember, in some cases “cancer-free” is the result.
All cancers are not created equal, and how it develops in each pet is also not equal. As a general rule, there are some patterns with different cancer types. Cancer is divided into three groups:
1. Benign Cancers- these are considered to be insignificant. They are not invasive and do not spread to other areas of the body. However, depending on their location, they often create discomfort from pressure or expansion.
2. Locally Aggressive Tumors- these are tumors that are benign by definition because they do not spread to other locations or organs. However, these tumors are far from being benign as they continue to invade into the surrounding tissues and destroy everything in the path.
3. Malignant tumors – these are locally aggressive and spread from the original location to other areas and organs.
Even using this classification produces confusion because there are a wide variation and various degrees of all these classifications. Thus, a more useful classification is to identify the type of tumor by the tissue from which it originates. Names such as lipoma or liposarcoma tell us benign or malignant. These can be identified by either biopsy or fine needle aspirate. Once a name is applied to a tumor, such as a histiocytoma, then an anticipated growth and reaction pattern for that tumor type can help make proper therapy decisions.
Yet, even knowing the tumor type does not always answer all the questions. For instance, mast cell tumors are easily diagnosed by fine needle aspirate, yet are further divided into four grades. Grade 1 is benign and Grade 4 is very malignant. The characteristics of these grades require a pathologist’s evaluation after the tumor is removed. The final therapy recommendation is then based on the grade assigned by the pathologist.
Often attempts are made by individuals to determine the severity of the tumor by its appearance or location. This is highly deceiving. The most common misdiagnosed tumors are those of the liver and spleen. Commonly, large tumors of the spleen or liver identified by palpation or radiographs are presumed to be malignant because of their size.
For example, hemangiosarcoma is a malignant tumor of the spleen and liver. Unfortunately, many animals have previously been euthanized without further evaluation because of the size. Today, an ultrasound of the organ gives many clues to suspect whether or not these tumors are benign or malignant. Further diagnosis by a biopsy is the only certain way to determine tumor type. Sometimes, these tumors bleed into the abdominal cavity as part of the large benign growth ruptures. Benign tumors of the spleen, such as hemangioma or nodular hyperplasia, are totally cured by splenectomy.
Cancer is not a death sentence! Early diagnosis and proper treatment lend much to our having quality time with our fur babies, and it adds to their life or possible cure.