Top 10 Warning Signs of Cancer in Dogs and Cats

Cancer is the leading cause of death in cats and dogs: learning to recognize early symptoms could save your pet’s life.

May is Pet Cancer Awareness Month, a time to spread awareness of the symptoms of cancer in dogs and cats. As cancer is the leading cause of death in cats and dogs, knowing the symptoms your pets may present if they develop the disease can help you and your vet diagnose and treat your pet sooner. In order to help you protect your pet’s health, petMD.com has pulled together the top 10 warning signs of cancer in dogs and cats.

1. Lumps and Bumps: Not every lump or bump is necessarily cancerous, but consulting with your vet is the only way to be sure. If the lump is growing or not resolving itself, contact your vet and he or she will do a biopsy to determine the contents of the bump.

2. Abnormal Odors: Foul odors from any of your cat or dog’s orifices and/or body parts may be a cause for concern. Cancers of the mouth, nose, or anal regions can cause your pet to emit offensive odors.

3. Abnormal Discharges: Discharges such as blood, pus, vomit, diarrhea, and any other abnormal substance being excreted from your pet’s body should be checked out by a veterinarian immediately. A bloated or distended stomach could also be a sign of internal discharge.

4. NonHealing Wounds: Lacerations or sores that do not heal within a normal time range on the surface of your cat or dog’s body may indicate infection, skin disease, and possibly cancer.

5. Weight Loss: Sudden weight loss in cats and dogs not on a diet can be an indicator of many diseases and illnesses. If coupled with another warning sign of cancer, you should contact your vet right away and inform him or her about your pet’s symptoms.

6. Change in Appetite: While a lack of appetite in dogs and cats can be an indicator of many things, they never stop eating without a cause. Not necessarily a sign of cancer, a decrease in appetite can indicate an oral tumor, which would make it painful and difficult for your pet to eat and swallow.

7. Coughing or Difficulty Breathing: Although symptoms of heart and lung disease, coughing and abnormal breathing can also indicate cancer. This symptom will most likely occur if the cancer in your pet’s body has metastasized into his or her lungs.

8. Lethargy and Depression: If your pet has cancer, there is a chance that he or she will suffer from depression and sleep more, become less playful, and be less willing to go for walks. Although lethargy or depression in dogs and cats can set in with any illness, it is commonly seen in pets that have cancer.

9. Changes in Bathroom Habits: Any changes in your pet’s bathroom habits including difficulty using the bathroom, frequent bathroom use, and blood in urine or stools are potential warning signs that cancer has developed in your pet.

10. Evidence of Pain: Limping or other evidence of your dog or cat in pain when he or she is active, or if the pain is too great for them to be active, can be indications of cancer of the bone.

While no one sign purely indicates cancer, a cat or dog displaying two or more of these symptoms should be taken to the veterinarian for an exam so that he or she can be properly diagnosed and treated accordingly, because early detection can make all of the difference in the case of a positive diagnosis.

46 thoughts on “Top 10 Warning Signs of Cancer in Dogs and Cats

  1. This is great for people to know, but the one thing I don’t see he is Hair loss. I lost my beagle to Lymphoma and hair loss was the only sign we had.

    1. My cat lost her hair above her eyes n around mouth then on the way to vet lost all hair on nose. She was at vets 2 weeks ago bc of bumps on skin n a croup cough. They gave her a steroid n antibiotic shot. Helped a Lil. But now hair loss n cogh n blood in nose. They want to cut her up. Like do 4 biopsies on her eyes nose mouth tomorrow then have her wear a cone. She has a heart murmur murder to. Am I doing the right thing of putting 11 yr old nervous cat through this. I just don’t know. My heart is broke. Thanks Julie [email protected]

      1. I had two cats with cancer and I knew the pain they would feel with surgery, I couldn’t do that to them,one shot and they were free of pain. Hope this helped

  2. What kind of hair loss Mina? Patchy? All over? My dog has had hair loss due to staph infections in his later years.

  3. Hombre and me are fighting together to defeat his bone cancer. We already knocked his liposarcoma into submission.

  4. You also need to know if your breed, and mixed breeds can be susceptible to the pure breeds, are more likely to develop. For instance GSD, from what I was told by my vet in Massachusetts, are likely to develop spleen cancer, which is what killed my last dog. He showed signs of being sick, took him in, we did a general exam, needle biopsy of a lump, and he was dead before the results were in. He was ill for maybe 2 weeks.

    1. Kirsten I just lost my baby 4 months ago he was with me for9years and 7 month he got bloted I call his vet they not wouldn’t check him out they wanted 300 dollars first I ask they if I could pay per month they wouldn’t see him they let my baby die I call them and told them they lost me as their customer because they let my baby die he was their patient and wouldn’t save him they let him die I know you send this message last year on may21 2012 but I didn’t have a computer the I hope you see this message message I wrote you he passed away 3 18 2013 he was born 8 8 2003 I buried him in my backyard with his blanket wrap around I put a little white fence around his grave with white rocks on top also a white cross that tells his name when he was born he has little angle a dog flowers in a vase ,plastic ones everything I put there with clear bags over them so that the sun won’t get to faded and keep the rain off of them I hope I get a answer back soon Mary

      1. i’m sorry, Mary. life is hard too often, and there is little those of us without power in this life can do sometimes. no matter how much we love.
        and it’s clear how much you loved your baby. i’m sorry you and your baby suffered so much. i hope you’ve been able to find some amount of peace now, although i know you will never forget your baby.

      2. So sorry for your loss, Mary. My grandfather was a veterinarian. He always helped animals no mayter what. If someone had no money to pay, they paod him with a chicken or something. And he was financially fine, even through the great depression. I wish there were more vets like him today…

  5. Our GSD died of spleen cancer as well. He was gone within a week. Although, the cancer had not spread from his spleen, he was 12 and didn’t wake up after the surgery.

  6. We found our dogs thyroid cancer while scratching his neck. Took him to the vet. This is a great article. Thank you

  7. My friend lost both her gsds to spleen cancer and my old (only 10) lab bitch had a cough within 3 weeks she had lost 5kg and I didn’t wake her up from her exploratory op …..rip Millie I miss ya girl xxx

  8. I have to have a Mast Cell Tumor removed on Friday by a specialist surgeon cause it’s so close to my tail and they have to create a little flap. It’s only the size of a pea but a 3 cm radius has to be taken to hopefully get a clear margin. Mum checks me over all the time, just to be sure. I am going to be fine but mum and dad love be so very much they’re worried sick. Great article…thank you!! 😀

  9. My Brodie GSP was diagnosed right @ 3 years ago. Vet said he would make it 6 months. I cherish every day with him.

    1. you are right its not us their owners its the vets because they all the time want a lot of money off the animals should have a vet that will take their needs free that loves animals and wants to help low income and poor people that don’t get very much money from mary

    2. I am sry to hear about ur dog .. I love dogs n I knw bout that felling after reading this I got tears In my eyeys:-[ :(:(:(:(

  10. My boy Biscuit (Chinese Shar Pei) had Mast Cell Cancer appx 2.5 years ago and had a tumor removed by surgery. We’ve been treating him with K9 Immunity ever since and I believe it has helped him remain cancer free… http://www.alohamedicinals.com They will work with your Vet for the best possible outcome…

  11. My dog is a blood donor and gets a complete blood, fecal and urine work up once a year for free
    Its a great little perk
    If you aren’t sure you can afford the tests on your own why not look into blood donation in your area?
    Donation is quick and not any harder on the dog than it is on you – my Ruby bounces back in a day or two and she gets to save lives!

  12. Sadly not any of these were evident with my Sarge. He was diagnosed with epilepsy at age 1 1/2. We now assume that the seizures were caused by brain cancer. Sargie passed shortly after his 4th birthday. He went into a seizure and didn’t come out. He was full of life, ate like a fiend, playful, fun and a wonderful baby. He had no tumors or patches or odd colour skin. The only indication of something was the seizures. We did treat the seizures with medication and for a year and a half to two years he was seizure free. Cancer never even entered into our heads or the Vets.

  13. My Golden Retriever “Samson” just got diagnosed with cancer in the lymph nodes. He’s 10 and I’d like to have him around longer but I’m struggling on what’s the best thing for him is right now…

  14. Our German Shepard lab mix has all of a sudden in the past couple of weeks developed a big bump on his back right leg. I am hoping its not something too serious cause I can not afford a vet visit or bill.

  15. I gotta question for those of u who r dog lovers. I have a husky he sheds every summer. Lately he hasn’t been eating very much. I can tell he has lost weight. He sleeps a lot but whenever we take him outside he runs round and goes crazy. I’m just worried cuz he doesn’t eat like he use to and he looks sad. The only symptoms I see, don’t eat much, loss weight n sleeps all day and runs round all night

    1. If you can’t affor to take your pets to the vet I’m sorry to say then you shouldn’t have them. It isn’t fair to them. It you can’t take them to a vet or feed them or whatever needs to be done. We have 3 dogs and no children. They are taken care of as if they are our kids.

      1. Some people don’t have much, but a pet might give them something to love and cherish, or the companionship they need. Some people might be desperately lonely, depressed or be experiencing other problems in their lives. In some countries there are animal charities that may help. Some ask for a donation or provide much cheaper alternatives to regular vet’s bills for those who may have lost a job, are disabled, or for other reasons have a low income. (These charities don’t moralise, but some may ask for proof of income) Incidentally, vet’s bills may be far too high when organisation exist like Animal trust (UK) My dog has to have Xrays later today which will hopefully allow for treatment that might help prolong his life. I can afford the £105 for these, whereas just under £500 quoted by Gyp’s previous vet might have felt a bit over the top in comparison. My reply at 4:50am when my dog’s appointment is not until 1:50pm might be some indication of how some of us feel when our dogs may gratefully feast on scraps of food in necessary, but ultimately loved til the end. The tears can go on for many years, but there is someone greater than ourselves who sees them.

      2. Just had my 12 year old lab die with cancer in her throat ,Yes she went to the Vet many times and every year for shots Also treated for CHF for almost 3 yrs ,Makes me sad that some people love Pets and don’t have the money to take them Pet meds and vet visits cost more than human health visits

  16. Please don’t moralise with people who are heartbroken/worried sick about a pet they love while not having much money. Maybe their pet gives them immense comfort when they don’t have much else to hope in at present. They’re company and are deeply loved. Losing them is one of the hardest things to bear and the tears that can flow for many years are hard enough to cope with. Animal charities exist in some countries for those who can’t afford regular vet’s bills. They may depend on donations or provide much cheaper alternatives. Some may require proof of income if on benefits/state aid (due to a job loss perhaps? Nobody judges there anyway) Humanity, please! Pets are grateful creatures who may feast on scraps of food if necessary. They’re loved and lovable…as are the people who love them to the end.

  17. My gorgeous wolf dog got cancer he was 12years old. We did not know at first that he had it as he was stiĺl acting like a puppy most days. He started limping on all fours and his breath was smelling badly, we thought it was just old age. He started being extremely tired and not himself. He was moulting a lot and I noticed 3 lumps under his fur. when he stopped eating his favourite things and drinking more water I took him to the vet’s. Thinking he would be ok little did I know. The vet checked him over and said he had aggressive cancer and had to put him to sleep. The thought of losing my best friend was unbearable but the vet said treatment would not work. I miss him every day but knowing he is not in any pain was the kindest thing to do.

  18. My dog Roc was a mix dog (Lab/Retriever) that was picked out of a puppy litter in Okinawa Japan , Kadena Air Base back in 2002 when he was six weeks old.. He had passed 30 Nov ’15 two hours before my wife and I were able to make it back to him from Arizona. He had a mass tumor in his stomach. Despite him being decease I still petted him and cried of course. He passed away peacefully in his sleep. Now we have his ashes in the house in a nice box. My dog lived a rock star lifestyle traveling all over the world with me since I was in the air force. I really misses his company. Rest in Peace buddy, I’ll see you when I get there.

    1. Malik, I am so sorry for your loss you have me in tears.
      I have a 12 yr old Jack Russell who started getting lumps on him first it was 1 then 2 and three, but 2 are gone. I only worry because this is weird he’s lost weight but only on his face and neck no where else. Have to wait until Monday to call the Vets for an appt. small town living is hard.
      I just can’t lose my Joey, I’ve already lost 5 ratties in 2015 I candle losing my dog too.

  19. I had a black lab and she had gotten plumes dease and I took her in to a vet they gave her some antibiotics and then I got her fixed then when she was 4 I took her to a other vet and was told that they was bad for her then they gave her a shot for the plumes and told me to take her off the pills and then she just passed away a month ago from throat cancer I feel the pills did it to her she was my baby she was with me through thick and thin she is very much missed I’m going through a deep depression from all of that so ya bad year I hope it gets better this new year

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