Cancer in Dogs and Cats: What You Need to Know
Mainstream veterinary oncologist Dr. Nicole Leibman on the most common cancers in dogs and cats — early detection is the single biggest determinant of whether common cancers are curable
Episode aired Apr 2, 2019·Page synthesised Mar 29, 2026·Last reviewed Mar 29, 2026
What this episode covers
- Nicole Leibman, a board-certified veterinary oncologist at the Schwarzman Animal Medical Center in New York (the world's largest non-profit animal hospital), gives a clinical overview of cancer in companion animals: the most common cancer types in dogs and cats, why naturally-occurring tumors in out-bred dogs are an unusually good translational model for human cancer research, breed-specific risks, and what owners should watch for at home.
- The central practical message is that many common pet cancers (mast cell tumors, lymphoma, certain melanomas) are highly treatable or curable when caught early, and that annual veterinary screening from middle age is the most reliable strategy owners have.
- The episode is grounded in mainstream veterinary oncology consensus.
Why it matters
Cancer affects roughly 45% of dogs over age 10 and 32% of cats, and is the leading cause of death in older companion animals. Most of the framings in this episode are mainstream veterinary oncology consensus from a board-certified veterinary oncologist at one of the world's largest non-profit animal hospitals — early detection, breed-specific risk awareness, annual screening from middle age, and an empirically grounded view of which cancers are highly treatable when caught early (mast cell tumors, lymphoma, certain melanomas). What is genuinely contested in veterinary oncology is the optimal timing of spay/neuter for cancer risk (early-spay reduces mammary cancer risk but may modestly elevate certain orthopedic and other cancer risks in some breeds), how aggressively to image asymptomatic senior pets, and which specific environmental factors matter most. What survives the disagreement is concrete: annual veterinary visits from middle age with a thoughtful screening discussion, immediate aspirate of any new lump rather than 'wait and see', and learning the early-warning signs of the cancers your breed is predisposed to.
What stands out
- Pet cancer rates have risen partly because pets are living longer — vaccines, parasite control, and better veterinary care now keep dogs and cats alive long enough to develop the age-related cancers that previously killed humans before veterinary medicine could address them. This is a sign of better care, not worse.
- Naturally-occurring cancers in out-bred dogs are unusually predictive of human cancer treatment outcomes — much more so than lab mouse models. The Animal Medical Center collaborates with Memorial Sloan Kettering and NYU Langone on comparative oncology research where dogs get clinical-trial access to treatments developed for humans, and human research benefits from cleaner translational data than mouse models provide.
- A soft lump can be a fatty lipoma (benign and common) or a mast cell tumor (cancerous and time-sensitive); they can feel identical. Aspirating any new lump with a needle takes minutes in the veterinary clinic and meaningfully changes the outcome for the dog if it turns out to be malignant. 'Wait and see' on a new lump is one of the most consistent missed opportunities in pet cancer care.
Best-supported action
The single highest-leverage move from this episode, anchored in the strongest evidence the speaker presents.
From the time your dog or cat reaches middle age (roughly 6-8 years for most dogs, 7-10 for cats — giant breeds age faster and may benefit from senior screening earlier), book a full annual veterinary visit with bloodwork and discuss with your veterinarian which breed-specific cancers to screen for. Early detection is the single biggest determinant of whether common pet cancers are curable.
Where to start
Small low-friction starters covering the main moves from this episode.
- Run your hands over your pet weekly during normal play or grooming time — get familiar with what their body normally feels like so a new lump or change is immediately noticeable
- Report any change that lasts more than a week to your veterinarian: a new lump, a sore that doesn't heal, persistent limping or stiffness, unexplained weight loss, changes in appetite or energy
- At your pet's next annual visit, ask which breed-specific cancers they are predisposed to and what the appropriate screening cadence is for their age and breed
Other supported actions
Further actions discussed in this episode, ordered from strongest to weakest evidence. This is one expert's view, the full topic compares and ranks across experts.
- From middle age onward (roughly 6-8 years for most dogs, 7-10 for cats; giant breeds age faster and may benefit from senior screening earlier), schedule a full annual veterinary visit including bloodwork and a thorough physical exam. Discuss breed-specific cancer risks with your veterinarian and agree on a screening cadence appropriate for your pet's age, breed, and size. This is the foundational move with the strongest evidence in veterinary oncology — early detection meaningfully changes outcomes for most common pet cancers.Strong evidence
- For senior dogs and cats (roughly 8+ years), discuss with your veterinarian whether adding chest X-rays and abdominal ultrasound to the annual visit is appropriate for your pet's breed and risk profile. The benefit varies by breed and individual situation; for elevated-risk breeds (Golden Retrievers, Boxers, Bernese Mountain Dogs, Rottweilers), the added imaging often shifts cancer detection earlier when it is most treatable.Moderate evidence
- Run your hands over your pet weekly during normal play or grooming time and note any new lump, sore that doesn't heal, persistent limping, or unexplained weight loss. Report any change lasting more than a week to your veterinarian — and ask for a needle aspirate on any new lump rather than accepting 'it's probably just fatty' as a final answer. Aspiration takes minutes and is one of the highest-value diagnostic steps in pet cancer care.Strong evidence
Full context, impact ratings, and timing — available in related topics
Questions to take to your doctor
- Given my pet's breed, age, and individual history, which specific cancers should we be most aware of, and what cadence of screening do you recommend (annual bloodwork? imaging? abdominal ultrasound? at what age)?
- If you find a new lump during a visit or if I find one at home, will you routinely aspirate it before calling it benign, or do we make that decision case by case?
- For my senior pet (8+ years), what specific blood markers and imaging would you add to the annual visit, and at what age would you start them?
- If my pet has a suspicious finding (lump, persistent limp, sore that doesn't heal, unexplained weight loss), what is the typical diagnostic pathway, and what are the time-sensitive decisions in that pathway?
- Given my breed (or my pet's specific situation), would a referral to a veterinary oncology specialist for an initial conversation be appropriate as part of senior-pet planning, or only if something is found?
Full doctor prep with ranked questions available in the full topic page
Context
Board-certified veterinary medical oncologist at the Schwarzman Animal Medical Center in New York City — the world's largest non-profit animal hospital. Specializes in cancer diagnosis and treatment in companion animals and is an advocate for comparative oncology research that bridges veterinary and human medicine through academic collaborations with Memorial Sloan Kettering and NYU Langone. Distinctive intellectual frame: early detection is the single most powerful tool in pet cancer care, breed-specific risk awareness shapes screening cadence, and naturally-occurring canine tumors are an unusually good translational model for human cancer research. Strongest source category: mainstream veterinary oncology consensus from a major academic-clinical center; framings sit at established standard of care rather than contested integrative territory. Minimal commercial conflict, no advocacy-organization positioning.
This episode is a clinical overview by a board-certified veterinary oncologist, not a study or systematic review. The specific screening recommendations (annual bloodwork from middle age, imaging from senior years, immediate aspirate on new lumps) are well-established mainstream veterinary oncology practice but are not always formalized as published guidelines for asymptomatic screening in the way they are for human medicine. The framework reflects clinical experience at a major veterinary oncology center; individual veterinarians may make slightly different recommendations based on your pet's specific situation.
The central practical claims — that early detection meaningfully changes outcomes for most common pet cancers, that needle aspirates on new lumps are high-value diagnostic steps, that osteosarcoma in large breeds is time-sensitive, that mast cell tumors are commonly mistaken for lipomas — are mainstream veterinary oncology consensus and align with published clinical literature. The 'comparative oncology' framing (naturally-occurring canine tumors as a translational model for human cancer research) is also mainstream and is the basis of the NIH's Comparative Oncology Program and similar academic-clinical collaborations.
What the episode does not provide: specific dosing protocols, breed-by-breed survival statistics, or randomized-trial data for specific treatments. It is appropriately positioned as orientation for owners deciding what to do, not as a substitute for breed-specific or pet-specific veterinary oncology consultation. Bottom line: the foundational moves Leibman recommends (annual screening from middle age, immediate aspirate on new lumps, X-ray on persistent limping in senior large breeds, breed-aware vigilance) are mainstream veterinary oncology and survive any reasonable disagreement at the margins.
Where people go wrong
- Accepting a 'probably just a fatty lump' assessment of a new lump without a needle aspirate to confirm.Mast cell tumors and other malignant masses can feel identical to lipomas. A needle aspirate takes minutes in the veterinary clinic, costs little, and meaningfully changes outcomes if the lump is malignant. Months of 'wait and see' on a mast cell tumor can move a small surgical case into a more advanced cancer with worse prognosis.
- Assuming a senior dog's stiffness or limp is arthritis without ruling out bone cancer.Osteosarcoma progresses quickly, particularly in large breeds (Great Danes, Greyhounds, Rottweilers, Irish Wolfhounds). The window for limb-sparing or amputation surgery closes faster than most owners expect, and prognosis depends heavily on early detection. An X-ray on persistent limping rules it out in minutes and is one of the more decision-changing imaging studies in senior-dog care.
What to expect over time
- Adult years (1-5)Cancer risk is generally low in healthy young adult pets. Standard annual veterinary visits, breed-appropriate parasite and vaccine care, and weight management are usually sufficient. This is also the window to establish a baseline relationship with a veterinarian who knows your pet's normal physiology — that baseline becomes valuable later.
- Middle age (6-8 for most dogs, earlier for giant breeds)Cancer risk begins to climb in this window for most breeds. Giant breeds (Great Danes, Irish Wolfhounds, Bernese Mountain Dogs) age faster and may benefit from senior-style screening starting at 4-5 years. Full annual bloodwork and a thorough physical exam become the most useful screening tools. This is also a good window to have an explicit conversation with your veterinarian about which breed-specific cancers your pet is predisposed to and what the appropriate cadence and depth of screening should be.
- Senior years (8+)Imaging (chest X-ray, abdominal ultrasound) and closer hands-on home checks meaningfully increase the chance of catching tumors early. For elevated-risk breeds (Golden Retrievers, Boxers, Bernese Mountain Dogs, Rottweilers), the added imaging often shifts cancer detection earlier when treatment options are broadest. Quality of life remains the primary metric — most older pets with well-managed cancer can live well for extended periods with appropriate care.