Diagnostic tests are necessary to determine the type of cancer and to know if the cancer has spread into other areas of the body (metastasis). Your veterinarian will need to perform the initial tests to get a cancer diagnosis. Once the type of cancer is known, we then can appropriately schedule your pet. After the initial consult with the oncologist, more diagnostics may be recommended which can performed at our facility.
- Complete Blood Work
- Fine Needle Aspirate
- Flow Cytometry
- CT scans
- Technetium scan for radioiodine treatment
X-rays in pets (also called radiographs) are performed much the same way they are in humans. This diagnostic test can be very helpful in looking at certain parts of the body. In order to see something on x-ray however, two different densities of tissue must be touching. In other words, the bone in a leg surrounded by muscle shows up very nicely. In contrast, a soft tissue mass inside of a soft tissue organ will not show up.
At Arizona Veterinary Oncology, the most common radiographs that we perform are of the lungs which allows us to look for spread of the cancer. To see metastasis (spread) within the lungs on an x-ray, the mass must be at least 7 to 9 mm large. More often than not, your pet can be awake for this procedure. We always recommend three views of the thorax (chest) (left side lateral, right side lateral and ventral-dorsal (pet lying on its back)).
The next most common place we radiograph are the long bones. Tumors that invade into bones show up very well on x-rays. Again, your pet can usually be awake for this procedure but sometimes the positioning may be uncomfortable, and sedation or anesthesia may be more appropriate.
At Arizona Veterinary Oncology, our X-ray system is completely digital. This allows us to share the X-rays with your veterinarian quickly via email as well as our radiologist for final interpretation. Most veterinary practices in America have the ability to perform radiographs today and your primary veterinarian maybe able to do these tests as well. If your veterinarian has performed X-rays recently, please be sure to have those sent to us or go by and pick up a CD containing the images and bring it with you to your appointment.
Ultrasound in dogs and cats is a very common and widely available diagnostic test. At Arizona Veterinary Oncology, we work closely at each of our locations with specialists that provide this testing.
Most people are familiar with ultrasounds because they are used most commonly in women to look at babies before they are born. It is very common to look at the heart with ultrasound as well. The term ultrasound refers to the sound waves that are emitted by the probe of the machine. The sound is outside the range that a human can hear. The probe also “catches” the sound when it bounces off the structures in the body and comes back. This process allows the computer to formulate a moving picture on the screen for the radiologist to review. The hair over the area being imaged will need to be shaved. Just as with pregnant women, ultrasound gel will be applied to the skin to help the sound waves travel into the body and back. This gel is non-toxic, odorless and colorless. While we strive to remove all the gel, it is not uncommon to have a small amount remain on the skin following the study.
While to you and me the images looks something like static on a TV without a signal, to the trained eye the images show what is happening inside the body and inside the organs being viewed. Subtle changes to an organ like the liver may be an indication of spread of cancer or the valves of the heart may be abnormal and leaking. Ultrasound allows us to see these things. The American College of Veterinary Radiology, the overseeing group for radiology, strongly suggests that ultrasounds be performed by board certified radiologist using high quality ultrasound machines and feels that the quality of the study is very dependent on those two factors.
In most cases, your friend can be awake for the study. It is possible in many cases to use ultrasound to help guide fine-needle aspirates or biopsies of masses or organs under the skin. For these procedures, sedation or anesthesia may be required. Generally speaking, the risk is low for those procedures. Bleeding is the most common side effect and in very rare cases can be life threatening. If your pet has an ultrasound-guided biopsy performed and there was a problem, you might see them become very lethargic, pant more, have a bloated abdomen or pale gums in their mouth. If any of these things are seen, you should contact a veterinarian right away (even if this means the veterinary emergency service if it is after hours). Results are usually available right away. Ultrasound for dogs and cats is available at Arizona Veterinary Oncology.
CT Scans For Pets
CT scans for pets are becoming more readily available. Even 10 years ago, this type of advanced diagnostic testing was rarely available for animals. At Arizona Veterinary Oncology, we are proud to have access to on-site Computed Tomography (CT) scanning at all three of our locations. In Gilbert, our 64-slice CT Scanner is the most advanced system for animals in Arizona. This extremely fast and detailed machine provides excellent image quality in a very short amount of time.
CT scans utilize X-rays to produce the image. Unlike the two-dimensional radiographs (commonly referred to as X-rays) however, CT scans provide a three-dimensional image of your pet. CT scans may be used for diagnosing a tumor or may be used for radiation treatment planning. CT scans are excellent for looking at bone and good for looking at soft tissues. Very often, a contrast agent is injected into the vein during the scan to help identify different tissue types.
Tumors have abnormal blood vessels that are very leaky. We rely on the fact that iodine based contrast agents want to get out of the blood vessels as fast as possible. When viewed on CT scans, the iodine leaks out into the tumor tissue faster than the surrounding tissue and therefore highlights the location and extent of the tumor. Common places that are scanned when pets have cancer include the lungs, the head, the abdomen and the long bones. When we look at the lungs, we can see primary tumors (i.e. tumors that started in the lungs) or we can see metastatic disease (i.e. tumors that have spread from other locations). Many tumors spread to the lungs because that is the first place the tumor cells get stuck in the tiny blood vessels. When we scan the head, we can see abnormalities such as nasal tumors, oral tumors or sometimes tumors of the brain. Within the abdomen, a CT scan may reveal masses in the various organs and can help us identify the lymph nodes from the back half of the body that might be diseased. For bones, it can sometimes be very difficult on a two-dimensional X-ray to tell if the bone is broken or not. With CT scans, we can make three-dimensional images that help the radiologist get a better look at the bone.
For stereotactic radiotherapy planning, your pet will likely be placed into an immobilizing device prior to the CT scan. This device will allow us to position your pet accurately on the treatment table and mimic the positioning that was used on the CT table. The immobilization device can only be made with your pet anesthetized and must be done at our Gilbert location. If a CT scan or MRI has been performed at a different facility, please be sure to bring a CD containing the images to your appointment. If you would like to pursue stereotactic radiosurgery, we may need to repeat the CT scan with immobilization so we can accurately plan your pet’s treatment.
CT scans can also be used by the surgeons to help plan their approach for surgery. Our surgeons also work closely with the radiologist to try and get as much information as possible prior to your pet being under anesthesia to ensure that the procedure will go as smoothly and safely as possible.
Ask your veterinarian if a CT scan for pets is a good diagnostic test for your friend today.
MRI stands for Magnetic Resonance Imaging and is becoming a more commonly used diagnostic test for our dogs and cats. This diagnostic test is only available at a limited number of locations in the Phoenix valley but we work very closely with those that provide this service and can help you choose the best location for you and your pet.
Unlike in people, our animals either need to be sedated or anesthetized for this procedure. While the scanning is not painful, it can take more than an hour to obtain the hundreds of images that make up the study. Because of this, the anesthesia does not need to be very deep and often only limited sedatives or tranquilizers need to be used. Your patient will most likely have a catheter placed into a vein so that medications and fluids can be administered while they are asleep. An MRI study involves many different scans that look at different things. The studies are obtained without the use of radiation. Instead, strong magnetic fields are applied to the patient. An MRI machine looks very much like a CT scanner. A table (couch) supports the patient and they are moved in and out through the gantry (opening in the machine). By measuring these magnetic fields as they pass through the patient, we can identify different types of tissues and fluids. By changing the magnetic fields, we can highlight different features of the tissues as well. Because of this, the patient often must pass through the gantry (opening in the machine) many times to complete the entire study. The catheter also allows contrast material to be injected. The contrast material helps us to better identify structures that we are interested in. The contrast does not like to be inside the veins and as such, is always trying to get out. Structures like tumors have very abnormal and leaky blood vessels. Because of this, the contrast “leaks” out of the veins within the tumor faster than it does from normal tissues.
The contrast can be easily seen on the scan and helps to highlight these structures.
MRI works best for soft tissues (i.e. not bones). Our colleagues that specialize in neurology use MRI scans to look at the brain and spinal cord more than anything else in dogs and cats. This test is very good for finding tumors in those structures. MRI is sensitive enough to tell the difference between a solid tissue, clear fluid (edema) and blood. For radiation treatment planning, we often use a combination of MRI and CT scans (computed tomography) to get the best of both worlds (CT is better for looking at things like bones and air-filled cavities like the lungs). With our advanced treatment planning software, we can fuse the images together and look at the best parts of the MRI and CT at the same time. Surgeons are starting to use MRI in animals just as they do in humans to look at structures like tendons and ligaments, particularly in the knee. At Arizona Veterinary Oncology, we can help coordinate an appointment for you with our colleagues in the Phoenix Valley that offer MRI as a diagnostic test for dogs and cats.