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13 Signs Your Chihuahua May Have Cancer

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13-signs-your-chihuahua-may-have-cancerI remember sitting in my home office and watching my fluffy white terri-poo Joey stand up. The little lump that I had felt on his back leg a few days prior was suddenly huge! How did that happen in just a few days?

What was even worse was that there were some spots of blood on his dog bed. I checked the lump and it had cracked open. I’m not sure if Joey had been scratching at it or it just opened because it had grown so big so fast, but there was a foul odor coming from it.

I immediately got him in to see my vet who suspected cancer. Even if it wasn’t cancer, it needed to be removed as quickly as possible to avoid infection so he was operated on the next day.

Turns out it was cancerous and a fast-growing kind. Fortunately, though, it was isolated and hadn’t gone to any other organs so he didn’t need radiation or chemotherapy.

Joey was 13 when this happened and despite the warning from my vet that it would probably come back, it never did. He lived almost another 6 years.

Cancer can strike almost any animal, and our pets are no exception. Like many diseases, cancer is more common in older animals but can affect pets of any age. So, without becoming or getting paranoid about it, you want to be on the alert for possible signs of trouble.

According to Cancer Vet Centers, the 5 most common types of cancers that dogs get are:

  • Bone Cancer also known as Osteosarcoma
  • Hemangiosarcoma
  • Lymphoma
  • Mast Cell Tumors
  • Melanoma

Of course, they can get other kinds of cancer but those are the most common types.

The possible warning signs of cancer in chihuahuas are about the same as for any dog and can also be potential indicators of a wide array of other health problems.

Only your veterinarian can determine if your pet has cancer for sure. By all means, if you spot one of these signs, have your vet check it out. It might mean nothing more than a minor issue and knowing that would contribute a lot to your peace of mind!

Look out for these signs, especially in chihuahuas over the age of 10:

• Lumps or skin masses – Many are benign in chihuahuas, especially things like sebaceous adenomas or lipomas. Unfortunately, some masses can be malignant, i.e. mast cell tumors or sarcomas. These generally appear under the skin and will progress in size. Any new lump or bump should be evaluated by your veterinarian and sampled

• Sores, especially with bleeding or discharge that do not heal normally

• Swollen lymph nodes – These can be a sign of cancer-like lymphoma. Other infections or immune-mediated diseases can cause swollen lymph nodes 

• Unexplained weight loss (or gain) – especially a distended abdomen. These can be signs of internal masses

• Pale gums can be a sign of internal bleeding from a ruptured mass or anemia 

• Bruising can be a sign of bleeding masses under the skin 

• Apparent difficulties with eating or swallowing. Check your pet’s mouth and be sure there is no evidence of oral tumors like melanoma or soft tissue sarcoma

• Lethargy and lack of stamina or loss of appetite

• Unusual odors (although remember, chihuahuas are prone to bad breath and dental issues)

• Indications that the dog is uncomfortable in certain physical positions

• Digestive symptoms such as vomiting and diarrhea

• Changes in elimination habits

• Respiratory difficulties can be caused by primary lung tumors or other cancers that can cause metastatic disease 

• Odd behavior

How will I know if my Chihuahua has cancer? 

If you’re concerned about your Chihuahua for any reason, you should seek guidance from your veterinarian. Even if you aren’t concerned, Chi’s should have wellness visits with their veterinarian yearly for a basic physical exam and screening bloodwork.

If your veterinarian is concerned about cancer, they may recommend some of the following tests:

  • Bloodwork – this will evaluate organ function and also red and white blood cell levels. Some cancers can affect the way the liver or kidneys work. Other cancers will cause blood loss or very high levels of white blood cells. 
  • Urinalysis – some cancers of the bladder or kidneys can effect urine production. Sometimes cancerous cells can be found in the urine. Specific urine testing can be performed to screen for diseases like bladder or prostate cancer. 
  • X-rays – these can be used to rule out metastatic disease in the lungs or to look for masses in the abdomen. 
  • Ultrasound – if your vet feels a mass in the abdomen, they may recommend an abdominal ultrasound. This is a very sensitive test to screen for tumors and determine where the tumor could be coming from. 

How will I know what kind of cancer my Chihuahua has? 

Often an aspirate or biopsy is required to diagnose cancer. Aspirates are when a veterinarian will take a small needle and poke the mass or lymph nodes. This will provide a sample of cells that will be placed on a microscope slide for pathologists to review.

Some tumors are not amendable to aspirating to achieve a diagnosis. In that case, your veterinarian may recommend a surgical biopsy to remove the mass and send the whole thing out for pathology review.

The whole mass is often removed and for benign diseases, this can be curative. Sometimes aspirates are performed first to help aid with surgical planning to remove the mass. Certain tumors, like mast cell tumors, require a large amount of tissue surrounding the tumor to be removed to ensure the surgical margins are clean. 

Can cancer in dogs be prevented?

Not always, and not consistently. Of course, a well-cared-for dog such as yours will present fewer health problems generally, but cancer does not always respect your best efforts. 

Are all dog tumors malignant?

Certainly not – no more so than in humans. Your vet can advise you on the best way to deal with benign growths.

Can dog cancers be treated?

Often, yes. Admittedly, treatment is not guaranteed success and can be expensive. But it is often worth a try. A good veterinarian will present you with the full range of options from the least to most aggressive and the least to most costly.

Although sometimes there is no avoiding the worst-case scenario, in many instances, it is worth fighting for our chihuahuas. If we can gain them more years of life with no significant loss of quality, both we and the dogs are winners.

Cathy signature Chi

woman kneeling in front of a dog outside in snow

Paula Simons


This article has been reviewed, fact-checked, and approved by Dr. Paula Simons DVM. You can read more about her on our About page.

Madeline E Banyas

Saturday 2nd of September 2023

Lost my chihuahua, Henry to stomach cancer. he was loving and fun and 14 yo. It broke my heart. We have a new chihuahua and i named him Rusty. He is sweet. I love chihuahuas, they are the best.

Cathy Bendzunas

Sunday 3rd of September 2023

Yes they are the best and I'm so sorry you lost Henry!

Janette Blaydes

Tuesday 14th of September 2021

My heart is breaking 💔😢😪I have no money to have my dog checked at the vet. I asked if they would see my dog and take a post dated check for 10days, they all say no. Prayers 🙏she makes it until then. So inhumane when itd all about $ over a dear pets life. Please Pray🙏For🐕Kiaras Great Healing In JESUS Mighty Name,😢🙏Amen🙏


Tuesday 24th of January 2023

@Janette Blaydes, I am in the same boat and sitting listening to my sweet little baby cry is breaking my heart ! She was rescued by a girl I was with for years and but I was the one that kept them do to her living situation, my daisy has grown on me so much ! It’s killing me that I can’t afford to help her! I don’t know what to do really and your right it should be about the animals life not the money ! I would and could gladly make a payment to have my best friends life saved ! It’s just the most helpless feeling in the world ! And it has happened at a really bad time , and before all the people say well if you can’t take care of them don’t get them , sometimes they come in your life without you wanting them and I do care for them but not everyone is blessed with luxury life of money . If anyone in the Bradenton,Fl area can help please reach out to me Thanks 🙏


Tuesday 14th of September 2021

I'm so sorry Janette! Can you possibly get Care credit? I have a card now that I only use for vets and then pay it off. I also have pet insurance but it doesn't pay up front so it's not much help in situations like these. We do have an article that may give you a few ideas:

I talked to a vet at a party one time about how they don't seem to help people out anymore in situations like yours, and he told me it's because they have been burnt too many times by people promising the money later, or writing post dated checks, etc. He said they run with small profit margins as it is and if they keep helping people who can't afford to pay, they have to close down. So they have to say no to everyone. I kind of understand his point of view. Although I don't think I personally could turn away a pet in need.


Friday 10th of September 2021

Hi my baby going to be 7 and he looks like 10. Found a small lump on his left side i have one on my right side. It don.t brother him and scared to death,it is cancer. I got to get appointment for him.


Friday 10th of September 2021

Yes, it's probably nothing but it's best to be safe, than sorry.


Saturday 6th of March 2021

I just noticed yesterday a large mass on my Daisy-bell a deer chihuahua, on her right side ribs. I am fearful The mass is not good. I can touch with no pain. Daisy-bell shows no pain. She is around 13 years old. I'm not sure of her age, she was a lost dog before I found her. Thanks Tina


Wednesday 1st of September 2021

@Cathy, Our 13year old female Chihuahua had what we thought was a lipoma growing under her left armpit/ribcage so we took her in to have her Vet take a look at it. She has had a benign lipoma removed before so we thought she may just be prone to them. We were wrong 😔. This time, the Vet aspirated it and viewed it under a microscope. Turns out, it is a mast cell tumor (cancer). Her surgery to have this one removed is next week. So glad we decided to make an appointment.


Saturday 6th of March 2021

Definitely get that checked out by a vet. It doesn't have to be painful to be cancer.

Linda lindsey

Friday 25th of December 2020

are teacup chihuahuas more prone to tumors in intestines


Friday 25th of December 2020

I haven't heard they were more prone to that in particular but they are more prone to health problems so it wouldn't surprise me.