How to Test for Cancer in Dogs?
Discovering that your dog might have cancer feels overwhelming. Your mind races with questions, and you want answers fast. The good news is that veterinary medicine has made huge strides in detecting cancer early, giving your furry friend the best chance at treatment and recovery.
This guide walks you through everything you need to know about testing for cancer in dogs. You’ll learn about the warning signs to watch for, the different types of tests available, and what to expect during the diagnostic process.
Why Early Detection Matters for Your Dog
Cancer affects dogs at alarming rates. Nearly 50% of dogs over the age of 10 develop some form of the disease. The earlier you catch it, the better the outcome. Early detection opens up more treatment options and can significantly extend your dog’s life.
Think of cancer screening like checking your car’s oil regularly. You catch small problems before they become expensive disasters. The same principle applies to your dog’s health. Regular checkups and staying alert to changes in your pet can make all the difference.
Dogs can’t tell us when something feels wrong. They depend on us to notice the subtle signs that something’s off. That’s why knowing what to look for and when to test becomes so important.
Common Warning Signs That Your Dog Needs Testing
Your dog shows you when something isn’t right. You just need to know what to watch for. Dogs over the age of 10 have a 50% chance of getting cancer, but younger dogs can develop it too.
Lumps and Bumps Under the Skin
Run your hands over your dog’s body during cuddle time or grooming sessions. Feel for any new lumps, bumps, or masses that weren’t there before. Not every lump means cancer, but lumps that are firm, grow quickly, or seem painful to your dog warrant a vet visit.
Check between the toes, under the tail, and everywhere else you can reach. Some cancers hide in unexpected places.
Changes in Eating and Weight
Has your dog stopped finishing meals? Loss of appetite or rapid weight loss is a sign that something isn’t right with your dog. If your normally food-motivated pup starts picking at their bowl, pay attention.
Unexplained weight loss happens even when dogs keep eating normally. The cancer disrupts how their body processes food and nutrients.
Breathing Problems and Coughing
If your dog has had a persistent cough for longer than a couple of days, or has started to display breathing difficulties, this can indicate more serious health issues. Dogs don’t catch colds like humans do. A lasting cough needs investigation.
Watch for heavy panting, wheezing, or struggling to catch their breath after minimal activity.
Bathroom Habit Changes
Changes in urination or bowel movements, including blood, unusual frequency, or accidents, could signal a problem with the bladder, kidneys, or intestines. Your house-trained dog suddenly having accidents isn’t just behavioral. It could point to cancer affecting their internal organs.
Track these changes in a notebook. Your vet will want to know the details.
Unusual Smells
If you notice an unusual smell coming from your dog’s mouth or ears, this is a warning sign of cancer in dogs. Bad breath could mean oral tumors. Ear odors might indicate growths in the ear canal.
Trust your nose. You know what’s normal for your dog.
Low Energy and Lethargy
If your dog is lethargic, and isn’t showing enthusiasm for its usual favourite activities, then you should be alert and have your pet checked. Your once-playful pup now sleeps most of the day. They tire out quickly on walks that used to be easy.
Energy changes happen gradually. Compare your dog’s behavior now to a few months ago.
Pain and Limping
Obvious signs of pain, such as limping or whimpering, could indicate an underlying health concern, such as cancer. Bone cancer commonly shows up as unexplained lameness. Your dog favors one leg or struggles to stand up.
Don’t dismiss limping as just old age, especially if it comes on suddenly.
Sores That Won’t Heal
Persistent, non-healing wounds or sores can be a sign that your dog’s immune system isn’t functioning properly. Wounds that stay open for weeks, bleed repeatedly, or look infected need immediate attention.
Cancerous growths sometimes look like regular sores at first.
Behavior Changes
Sudden aggression, hiding, or anxiety can be symptoms of internal discomfort and may indicate an underlying health issue. Your friendly dog becomes snappy. Your social pup suddenly wants to be alone.
Pain and illness change behavior. Don’t ignore these personality shifts.
Physical Examination: The First Step
Your vet starts with a thorough hands-on examination. They feel your dog’s body for lumps, check lymph nodes for swelling, and look inside the mouth for abnormalities. Your veterinarian will typically palpate your dog’s lymph nodes to check for any enlargement, which can be a sign of cancer.
The physical exam gives your vet clues about where to look next. They’ll press gently on your dog’s abdomen to check for organ enlargement or masses. They listen to the heart and lungs for unusual sounds.
This exam takes about 15 minutes. Your vet asks about symptoms you’ve noticed at home. Be specific about timeline and changes. Every detail helps.
Blood Tests: What They Can and Can’t Tell You
Blood work forms a key part of cancer testing. Abnormal blood work is not always a sign that your dog may have cancer, but it does warrant further investigation. Your vet checks white blood cell counts, red blood cell counts, and organ function.
Blood tests don’t diagnose cancer directly in most cases. They show when something’s wrong in the body. High white blood cell counts suggest the immune system is fighting something. Low red blood cell counts might indicate internal bleeding.
Your vet draws blood from a leg vein, just like taking a blood sample from you. Results come back within a day or two from in-house labs, or up to a week from outside laboratories.
New Blood-Based Cancer Screening Tests
Exciting developments now allow vets to screen for cancer using simple blood samples. OncoK9 demonstrated a 54.7% sensitivity and a 98.5% specificity in detecting 30 types of canine cancer.
Cancer screening tests for dogs detect abnormal particles in the bloodstream, such as nucleosomes or cell-free DNA. These tests don’t diagnose cancer directly. They signal that cancer may be present, prompting the need for follow-up diagnostics such as X-rays, ultrasounds, biopsies, or more advanced imaging.
Think of these screening tests as smoke detectors. They alert you to potential danger so you can investigate further. Your vet can perform these during annual wellness visits, especially for senior dogs or breeds prone to cancer.
Fine Needle Aspiration: Quick and Informative
When your vet finds a lump, they often perform a fine needle aspiration (FNA) right away. A fine needle aspirate collects a sample from your dog’s tumor or mass by inserting a needle into a target area and removing cells for review under the microscope.
The process is quick and usually doesn’t hurt much. Most dogs don’t even feel the tiny needle. No sedation is needed in most cases. Your vet inserts a small needle into the lump, pulls back on the syringe to create suction, and collects cells.
Those cells go onto a glass slide. The vet either examines them in-house or sends them to a pathologist. When done in-house, test results may be attained within minutes. When sent out to a lab, it may take anywhere between three and five days.
What FNA Can Tell You
Malignancy was detected by cytology in 69% of the malignant tumors. Fine needle aspiration works well for many cancer types. It can identify mast cell tumors, lymphomas, and many other cancers quickly.
The test helps your vet decide if a lump needs immediate surgery or can be monitored. It’s incredibly useful for checking multiple lumps at once.
Limitations of FNA
Fine needle aspiration doesn’t always provide clear answers. There are specific tumor types that don’t aspirate well, and samples are sometimes non-diagnostic. Sarcomas, for example, are dense tumors that don’t release cells easily.
Even when you can see the lump being aspirated, there is a small chance you may not get a good collection of cells if the tissue sample does not exfoliate well. When FNA results are unclear, your vet recommends a surgical biopsy.
Surgical Biopsy: The Gold Standard
When fine needle aspiration doesn’t give enough information, a surgical biopsy provides definitive answers. Histology is generally considered the diagnostic ‘gold standard’. This test examines actual tissue, not just individual cells.
Your dog needs sedation or anesthesia for a biopsy. The vet removes a small piece of the mass or sometimes the entire growth. A small piece of the mass is removed and sent to a pathologist.
The pathologist slices the tissue thin, places it on slides, and stains it for examination. Cancer cells have certain characteristics that allow the pathologist to determine the tissue of origin, whether or not it contains cancer cells, and often they can tell how severe the cancer is.
Results take longer than FNA. Biopsies have to be prepared, processed, and then read by a veterinary pathologist. This can take up to two weeks. The wait feels long, but the detailed information is worth it.
X-Rays: Looking Inside the Chest and Bones
X-rays (radiographs) help detect cancer in specific areas. X-rays are taken to check for any irregularities in the chest, bones, and sometimes the abdomen.
Chest X-rays reveal lung tumors or check if cancer has spread to the lungs. Bone X-rays show destructive lesions that might indicate bone cancer. Your vet typically takes multiple angles to get a complete picture.
The process is quick and painless. Your dog lies on a table while the technician positions the X-ray machine. Most dogs don’t need sedation unless they’re too anxious to stay still.
X-rays work great for some cancers but miss others. Soft tissue masses don’t always show up clearly on radiographs.
Ultrasound: Examining Internal Organs
Abdominal ultrasounds will bring any abnormalities to light. Ultrasound uses sound waves to create images of internal organs. Your vet can see the liver, spleen, kidneys, bladder, and other structures.
The technician shaves a patch of fur on your dog’s belly and applies gel. They move a probe over the area, watching the screen for masses, fluid buildup, or organ changes. The test is completely painless.
Ultrasound guides fine needle aspirations of internal organs. The vet watches the screen while inserting the needle, making sure they hit the right spot.
Results are immediate. Your vet can see masses and abnormalities right away during the exam.
Advanced Imaging: CT and MRI Scans
Complex cases require advanced imaging. CT scans provide detailed cross-sectional images that reveal the exact location, size, and impact of tumors. These scans give three-dimensional views that regular X-rays can’t provide.
MRI scans produce highly detailed 3D images, ideal for detecting changes in soft tissues, joints, and bone marrow. They work especially well for brain tumors, spinal masses, and other neurological cancers.
Your dog needs general anesthesia for CT and MRI scans. They must stay completely still for 30 minutes to an hour. The machines are loud and enclosed, which dogs wouldn’t tolerate awake.
These tests cost more than standard X-rays or ultrasounds. They typically happen at specialty veterinary hospitals. Your regular vet refers you to these facilities when needed.
Special Tests for Specific Cancers
Some cancers require unique testing approaches. Your vet chooses tests based on what they suspect.
Endoscopy for Internal Cancers
Endoscopy involves inserting a camera tube into your dog’s body. It examines the esophagus, stomach, intestines, or airways. The vet can see tumors directly and collect tissue samples.
Your dog needs anesthesia for this procedure. It’s often used when X-rays and ultrasound suggest gastrointestinal cancer but more information is needed.
Urinalysis for Bladder Cancer
Urinalysis is becoming more common for geriatric animals. Abnormal cells in the urine can indicate bladder cancer. Your vet collects urine through a catheter or by catching a sample when your dog pees.
The lab checks for blood, abnormal cells, and other markers of disease.
Lymph Node Aspirates
Swollen lymph nodes often mean cancer has spread. Your vet performs fine needle aspiration on enlarged nodes to check for cancer cells. This quick test helps determine cancer stage.
Understanding Test Results and Next Steps
Test results rarely come all at once. Your vet builds a complete picture piece by piece. Each test result is a clue that can point you toward the next step.
Sometimes results are clear. The biopsy shows a specific cancer type, and your vet knows exactly what to do next. Other times, results are unclear or conflicting. More tests become necessary.
Don’t hesitate to ask questions. Request copies of all test results. Ask your vet to explain anything you don’t understand. You’re your dog’s best advocate.
If cancer is confirmed, your vet discusses staging. Staging determines how advanced the cancer is and whether it has spread. This information shapes the treatment plan.
How Much Does Cancer Testing Cost?
Testing costs vary widely based on your location and which tests are needed. Blood work typically runs $100 to $300. Fine needle aspirations cost $50 to $200 per sample.
Surgical biopsies are more expensive, ranging from $300 to over $1,000 depending on the mass location and whether removal happens during the procedure. Advanced imaging like CT or MRI scans cost $1,000 to $2,500 or more.
Nu.Q Vet Cancer Screening Test and OncoK9 tests would be most effective when used on an annual basis, particularly in older dogs and in those breeds prone to cancer. These newer screening tests cost several hundred dollars.
Pet insurance sometimes covers diagnostic testing when cancer is suspected. Check your policy details. Some plans cover cancer screening for high-risk dogs.
Don’t let cost prevent necessary testing. Many veterinary clinics offer payment plans. Organizations like CareCredit provide financing for veterinary care. Your dog’s health is worth the investment.
High-Risk Dogs That Need Extra Monitoring
Certain dogs face higher cancer risks. Dogs over the age of 7, particularly those considered large or giant breeds, face an increased risk. Golden Retrievers, Boxers, Bernese Mountain Dogs, German Shepherds, and Rottweilers develop cancer more frequently than other breeds.
Large breeds like Great Danes, Irish Wolfhounds, and Scottish Deerhounds have higher rates of bone cancer. Flat-faced breeds face increased risk for certain tumor types.
If your dog falls into a high-risk category, schedule checkups twice yearly instead of annually. Ask your vet about cancer screening blood tests. Stay extra vigilant about lumps and behavior changes.
Spaying and neutering early reduces certain cancer risks. Dogs exposed to secondhand smoke face higher rates of respiratory cancers. Keep your smoking away from your pets.
Creating a Cancer Monitoring Plan
Take charge of your dog’s cancer prevention and early detection. Owners should be encouraged to take responsibility for prevention of cancer and frequent screening. Create a simple routine for checking your dog.
Run your hands over your dog’s entire body weekly. Make it part of grooming time or cuddle sessions. Keep a journal of any lumps you find, noting their size and location. Take photos if possible.
Schedule regular vet checkups. Senior dogs should see the vet twice yearly. Younger dogs need annual exams at minimum. Don’t skip these appointments even when your dog seems healthy.
Owners should be able to accurately evaluate mammary glands, peripheral lymph nodes, oral cavity structures, examine interdigital spaces and external ear canals. Learn what normal looks and feels like for your dog. This makes spotting changes easier.
Ask your vet about cancer screening tests during wellness visits. For high-risk dogs, the investment in early detection blood tests makes sense.
Common Questions About Cancer Testing in Dogs
How long does it take to diagnose cancer in dogs?
The timeline varies greatly. Simple cases with clear lumps might get diagnosed within a week through FNA. Complex cases requiring multiple tests can take several weeks. Routine bloodwork which may be back within a week or even the same day. More complex blood tests sent to specialty labs can take longer.
Can my vet diagnose cancer without a biopsy?
Sometimes, yes. Certain cancers have very characteristic appearances on fine needle aspiration. Blood cancers like lymphoma often get diagnosed through FNA alone. However, histology is often needed to determine if a tumor is benign or malignant.
Does testing hurt my dog?
Most cancer tests cause minimal discomfort. The discomfort is mild and likely similar to what is experienced during a vaccine, injection, or blood draw. Sedation or anesthesia protects your dog from pain during surgical biopsies and advanced imaging.
What if the test results are unclear?
Waiting for test results can feel like forever. Sometimes the first test doesn’t give clear answers. Your vet recommends additional testing to get a definitive diagnosis. This frustration is normal. Keep asking questions and stay involved in the process.
Should I get a second opinion?
Absolutely, if you feel uncertain about the diagnosis or treatment plan. Veterinary oncologists specialize in cancer cases. Your regular vet can refer you to one. Second opinions often provide peace of mind or reveal additional treatment options.
When to Push for More Testing
Trust your instincts as a pet owner. You know your dog better than anyone. If something feels wrong but initial tests come back normal, push for more investigation.
If we find cancers early, we can treat them better, just as with people. Don’t accept “let’s wait and see” if your dog is clearly sick. Request referral to a specialist if needed.
Your dog depends on you to advocate for their health. Be persistent. Ask for additional tests when you’re not satisfied with answers. Cancer caught early is often treatable.
The Bottom Line on Testing for Cancer in Dogs
Testing for cancer in your dog starts with paying attention. Notice the lumps, the behavior changes, the subtle signs that something’s wrong. Get your dog to the vet promptly when concerns arise.
Modern veterinary medicine offers many ways to detect cancer. From simple blood tests to advanced imaging, your vet has tools to find answers. Each test provides pieces of the puzzle.
Early detection saves lives. If we find cancers early, we can treat them better, just as with people. We can diagnose them quickly and get the treatment started quicker, and hopefully, that will mean that the prognosis is much better.
Stay proactive about your dog’s health. Schedule regular checkups. Learn what’s normal for your pet. Create a monitoring routine at home. These simple steps can catch cancer early, giving your furry friend the best chance at a long, healthy life.
Your dog gives you unconditional love every single day. Return that love by staying vigilant about their health and acting quickly when something seems off. The time you invest in cancer screening and testing could give you many more precious years together.
