Dog Cancer: Signs to Watch For, Skin Cancer and Treatment Options

Hearing the word "cancer" from your veterinarian is hard. It's also more common in dogs than many pet parents realize. This guide covers what cancer in dogs is, the signs worth flagging early, how veterinarians diagnose it and what treatment and supportive care can involve, so you know what to ask at each step.

Key Takeaways:

• The AVMA estimates about 1 in 4 dogs will develop cancer, rising to 1 in 2 for dogs 10 and older.
• Dogs can get skin cancer; mast cell tumors are the most common type.
• New or changing lumps, weight loss and sores that won't heal are worth a veterinarian visit.
• Your veterinarian builds a treatment plan based on cancer type, stage and overall health.

What Is Dog Cancer?

Dog cancer is the uncontrolled growth of abnormal cells somewhere in a dog's body. It can show up as a visible lump on the skin or develop internally in organs, bone or blood.

Definition: Canine neoplasia. The veterinary term for abnormal tissue growth in dogs. A tumor can be benign (it stays put and doesn't spread) or malignant (it can invade nearby tissue and spread to other parts of the body).

Veterinary oncology is the branch of veterinary medicine focused on diagnosing and treating cancer in pets. Veterinary oncologists often have waitlists of several months. The good news? Your general veterinarian can usually start diagnostic testing and supportive care while you wait for a specialist.

Can Dogs Get Cancer?

Yes. Dogs get many of the same cancers people do, including lymphoma, osteosarcoma (bone cancer) and several types of skin cancer. In its Cancer in Pets guide for pet owners, the American Veterinary Medical Association (AVMA) estimates that approximately 1 in 4 dogs will develop cancer at some point in their life, and that risk climbs to 1 in 2 for dogs 10 years or older.

A study by PetDx found a median age at diagnosis of 8.8 years, with larger dogs tending to be diagnosed younger. Based on that data, the researchers suggested starting cancer screening at age 7 for most dogs and as early as age 4 for some breeds.

Our Take: Breed and size matter. If you have a large or giant breed, don't wait for the "senior" label to ask your veterinarian about cancer screening at annual visits.

What Are the Signs of Cancer in Dogs?

The most common signs of cancer in dogs are lumps that grow or change, sores that won't heal, unexplained weight loss and changes in appetite or energy. Many of these overlap with less serious conditions, which is why a veterinarian's exam matters.

Source: AVMA, Cancer in Pets

So when should you call your veterinarian? Any time a sign lingers or a lump changes. Pain can be a sign too, and dogs are good at hiding it. Here's how to recognize the signs your pet is in pain.

Can Dogs Get Skin Cancer?

Yes, dogs can get skin cancer, and some types are common. According to the Penn Vet Ryan Hospital's guide to mast cell tumors in dogs, mast cell tumors are the most common skin tumor in dogs.

Source: American Kennel Club, Dog Skin Cancer Types, updated 2024

Not every lump is cancer. Lipomas (fatty tumors) and sebaceous adenomas are common benign growths. The catch is that benign and malignant lumps can look and feel alike. Mast cell tumors are an example.

How Do Veterinarians Diagnose Cancer in Dogs?

Veterinarians diagnose cancer in dogs with a physical exam, bloodwork, imaging such as X-rays or ultrasound, and a sample of the suspicious tissue through a needle aspirate or biopsy. From there, the process moves through staging, prognosis and a personalized treatment plan.

Some veterinarians also work with research partners during diagnosis. FidoCure uses genomic testing to identify genetic markers that may match a dog with targeted therapies. For lymphoma or leukemia, ImpriMed uses AI to measure how a dog's cancer cells respond to different oncology drugs in the lab, giving veterinarians more information when choosing medications.

What Are the Treatment Options for Cancer in Dogs?

The main treatment options for cancer in dogs are surgery, chemotherapy, radiation, targeted therapy and palliative care, often used in combination. Your veterinarian or veterinary oncologist recommends options based on the type and stage of cancer, your dog's overall health, and your goals for their care.

How is targeted therapy different from chemotherapy? Traditional chemotherapy affects rapidly dividing cells, both cancerous and healthy. Targeted therapies are designed to act on the specific molecular markers that drive certain cancers, such as blocking growth signals. Like all oncology drugs, they require a prescription and ongoing monitoring from your veterinarian.

Our Take: Many oncology medications are made in human-sized doses. Through compounding, we can prepare a veterinarian's prescription in a specific dose for your dog's weight, a once-weekly format or an alternate form that's easier to give. Every order includes what you need for safe handling at home, and we send proactive refill reminders so you're not left scrambling.

Veterinarians: send an oncology prescription to Mixlab →

What Supportive Medications Are Used for Dogs With Cancer?

Supportive medications are prescribed to manage the side effects of cancer and its treatment, such as nausea, stomach irritation, pain, and appetite loss. Your veterinarian will explain which side effects to watch for with your dog's specific treatment plan.

Wondering how prednisone and prednisolone differ? See our guide Prednisone vs. Prednisolone: What's the Difference for Cats and Dogs?

How Do You Choose a Pharmacy for Dog Cancer Medications?

Choose a pharmacy that carries a wide range of oncology and supportive medications, meets strict quality standards, delivers quickly and has a support team that understands how stressful this time is. Here's what to look for:

• Range of medications: Chemotherapy, targeted therapy and supportive medications in one place, including compounded options.
• Quality and compliance: Accreditation and strict quality control standards for every prescription.
• Fast, reliable delivery: Timing matters when your dog's treatment schedule is set.
• Caring support: Real people who can help with orders, refills and questions.

Why Pet Parents and Veterinarians Choose Mixlab

We're a PCAB-accredited pet pharmacy that fills chemotherapy, targeted therapy and supportive medications with a valid prescription from your veterinarian. With next-day delivery and a customer care team that knows oncology orders, we make one part of a hard season a little simpler.

Pet Parents: Ask your veterinarian to send your dog's prescription to Mixlab, or place an order.

Dog Cancer FAQs

What age do dogs usually get cancer?

In 2023, a PLOS One study of more than 3,000 dogs found a median age at cancer diagnosis of 8.8 years. Larger dogs tended to be diagnosed younger. The researchers suggested starting screening at age 7 for most dogs and as early as age 4 for some higher-risk breeds.

How long can a dog live with cancer?

It depends on the type of cancer, how advanced it is, where it's located, your dog's overall health and the treatment plan you choose. There's no single answer, which is why the prognosis step matters. Your veterinarian or veterinary oncologist can walk you through what to expect for your dog's specific diagnosis.

Is every lump on my dog cancer?

No. Many lumps are benign, like lipomas (fatty tumors) and sebaceous adenomas, according to the AVMA. But benign and cancerous lumps can look alike, so it's worth having your veterinarian check any new lump or one that's growing or changing. They'll often sample cells with a needle to find out.

What does skin cancer look like on a dog?

Skin cancer in dogs can look like a raised lump, a firm patch, a sore that won't heal or a growth that changes color or size. Melanoma may appear as gray or pink lumps in the mouth or swelling around a toe, according to the American Kennel Club. Only testing can confirm what a growth is.

Is cancer painful for dogs?

Some cancers cause pain, especially those affecting bone or that press on nearby tissue, while others cause little discomfort early on. Dogs often hide pain, so watch for limping, restlessness or changes in behavior. Your veterinarian can prescribe pain medications such as meloxicam or prednisolone when appropriate.

Do dogs need a prescription for cancer medications?

Yes. Chemotherapy, targeted therapy and most supportive medications for dogs require a prescription from a licensed veterinarian. Your veterinarian can send the prescription to a pet pharmacy like Mixlab, where it can be filled as-is or compounded into a specific dose or form that's easier for your dog to take.

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