Oncology

Cancer Topics

  1.  Symptoms
  2.  Diagnosis
  3.  Cancer Treatment
  4.  Cancer Survivorship

Recognizing Cancer Symptoms in your pet

Unfortunately many types of cancer do not display obvious symptoms or cause discomfort in pets until well advanced.  Early warning signs tend to be subtle, such as weight loss, and can be mistaken for other more common problems in aging animals.

  The Major Warning Signs of Cancer in Companion Animals:

  •  skin lumps or sores that do not heal
  •  changes in appetite, urination or bowel habits
  •  unusual bleeding or discharge
  •  persistent cough or difficulty swallowing food or water
  •  foul breath
  •  lameness that does not respond to medication

Some symptoms are specific to certain types of cancer, such as lameness seen with bone cancer.   Diagnostic tests are available for most common cancers.  If diagnosed early, chances of successful treatment are greatly increased.

Diagnosis of Cancer in Companion Animals

Early detection of a cancer before it is able to progress is challenging in veterinary patients.  There are however wonderful tools available for determining the diagnosis and “staging” of the cancer (determines the extent of cancer in the rest of the body).  Common diagnostic tests for veterinary cancer patients include:

Cytology:  A small sample of fluid is removed and the cells are evaluated microscopically for characteristics commonly associated with cancer.  This is a less invasive method of cancer detection.

Biopsy:  A small sample of tissue from the lesion is surgically removed and evaluated under a microscope.  This usually provides the most definite answer regarding the type of cancer present.

Diagnostic Imaging: X-rays, ultrasound, MRI (magnetic resonance imaging), CT scan (computerized axial tomography) and nuclear scintigraphy (eg bone scan) are techniques used to obtain images of the organs inside of the body.  These methods are used to define the local extent of the cancer and search for groups of cells that may have migrated to other areas (metastases).

Blood and Urine Analysis:  Evaluation of an animal’s metabolic function, cell counts and urine characteristics can be helpful to detect cancer in some cases.  Mostly these tests provide information regarding the overall health status of an animal and help determine what types of treatment are reasonable to consider.

Cancer Treatment: The Options

There are several types of treatment utilized for cancer in dogs and cats.  Recommended treatments vary according to the type of tumor, the patient’s current condition and the owners’ preferences regarding treatment.  The major types of therapy include:

Surgery: The oldest form of cancer treatment.  Generally is the most successful treatment for many types of neoplasia. 

Chemotherapy: “Chemotherapy” means drug therapy.  In an oncologic sense, this can be used to kill cancer cells, delay their growth or relieve pain symptoms.  There are many different drugs utilized for these purposes and they may be given singularly or in combination. These medications can be administered as an injection, as an infusion (an intravenous drip over several minutes) or as an oral medication at home.

Radiation therapy:  This is a targeted local treatment where high energy beams are used to destroy cancerous cells. In veterinary medicine, there are few centers which provide radiation therapy, however this modality is available in Colorado. Veterinary patients generally must be anesthetized for each treatment so as to minimize damage to surrounding normal tissue while the energy is delivered appropriately.

Immunotherapy: These are treatments that use the patient’s own natural defenses to fight cancer.  In veterinary medicine, this is a relatively new field of cancer treatment.  The most recently developed successful immunotherapy is a vaccine for  canine melanoma patients.

Angiogenesis Inhibitors:  In order for cancer to grow in the body, a blood supply is needed.  Some cancers are very effective in forming their own blood vessels to sustain growth.  Angiogenesis inhibition is a relatively new modality of treatment that stops this process and therefore delays growth of new cancer cells.

Palliative Care:  The goal of palliative care is to prevent and relieve the suffering of cancer patients.  This type of therapy is often thought of as “end  of life” treatment, or when other types of therapy have failed. In fact, this type of therapy is supportive care during the entire course of the patient’s definitive treatments (such as surgery or chemotherapy) that ensures the best quality of life.  If the patient’s cancer cannot be treated, then the focus of palliative care shifts to  pain control and discernment of appropriate time for humane euthanasia.

Cancer Survivorship

Early recognition, improved treatments and successful supportive care of veterinary cancer patients has helped achieve the goal of improved quality of life in many cases.   Cure is not always feasible in our patients, however long term remission (control) of the cancer is certainly possible in several instances.   Each patient’s condition is unique and we will discuss the realistic possibilities of treatment and anticipated outcome with each option.  Ultimately, the short and long term impact of cancer upon a companion animal and your family is critical to understand.

Common Cancer Types  (see handouts:  Resources:  Pet Health Library)

Cancer Treatments: