At Heartland Veterinary Hospital in Danville, Kentucky, we understand how deeply our pets are woven into our lives. That’s why we’re committed to empowering pet parents with knowledge—especially when it comes to one of the most serious health concerns pets can face: cancer.

This guide offers a thorough overview of common cancers in dogs and cats, signs to watch for, diagnostic approaches, and treatment options. Our goal is to help you recognize the early warning signs and feel confident in seeking timely, compassionate care for your pet.

What Is Cancer in Pets?

Cancer is the result of abnormal cell growth that invades surrounding tissues or spreads throughout the body. These growths can be benign (non-cancerous) or malignant (cancerous). While benign tumors typically don’t spread, malignant cancers can metastasize and require more aggressive treatment.

Like people, pets can develop cancer in almost any organ system—including the skin, bones, blood, and internal organs. It’s one of the most common illnesses in older dogs and cats.

Learn more: Cancer in Pets – AVMA

The Importance of Early Detection

Catching cancer early is crucial. Early-stage cancers often respond better to treatment and may be curable or manageable for years with the right veterinary care. Regular checkups allow us to identify unusual lumps, behavioral changes, or internal issues before they progress.

Does My Pet Have Cancer? – AAHA

Common Signs of Cancer in Dogs and Cats

Being attentive to subtle physical or behavioral changes can save your pet’s life. Contact your vet if you notice:

  • Unexplained weight loss
  • Lumps or bumps that grow or change
  • Wounds that won’t heal
  • Bad breath or difficulty eating
  • Lethargy or withdrawal
  • Sudden lameness or stiffness
  • Trouble breathing or using the litter box

Explore more symptoms at the Veterinary Cancer Society Pet Owner Resources.

Common Types of Cancer in Pets

Lymphoma

Affects the lymphatic system and immune function. Common in both cats and dogs, lymphoma may cause swollen lymph nodes, vomiting, and lethargy.

Learn about Lymphoma in Cats

Mast Cell Tumors (MCTs)

A common skin cancer in dogs. These tumors can look like simple skin lumps but may be aggressive or ulcerated.

Hemangiosarcoma

A fast-spreading cancer of blood vessel linings, often affecting the spleen or heart. Sudden collapse, pale gums, or abdominal swelling are red flags.

More on Hemangiosarcoma – Cornell Vet

Osteosarcoma (Bone Cancer)

Seen most often in large-breed dogs. Symptoms include limping, swelling over bones, or visible pain.

Canine Osteosarcoma Info – Cornell Vet

Oral Cancer

Includes squamous cell carcinoma, melanoma, and fibrosarcoma. May cause facial swelling, drooling, or reluctance to eat.

Oral Squamous Cell Carcinoma in Dogs – Cornell Vet

Oral Tumors of Small Animals- ACVS

Mammary Tumors

Common in unspayed female dogs and cats. These can be benign or malignant and usually appear as lumps near the belly.

Squamous Cell Carcinoma in Cats

Often found on the nose, ears, or mouth. Linked to sun exposure in light-colored cats.

Squamous Cell Cancer in Cats – Cornell Feline Health Center

More Types of Cancer in Pets – AAHA

How We Diagnose Cancer at Heartland Veterinary Hospital

Physical Exam & History

We start with a detailed exam and discussion of any recent changes you’ve noticed.

Fine Needle Aspiration (FNA)

A minimally invasive way to collect cells from a mass for analysis.

What Is FNA? – Today’s Veterinary Practice

Cytology vs. Biopsy – VetBloom

Biopsy

Surgical collection of tissue for definitive diagnosis, especially important for deeper or ambiguous masses.

Biopsy & Tumor Diagnosis – AAHA Oncology Guidelines

Diagnostic Imaging

We use X-rays and ultrasound to assess tumor spread or check internal organs. For complex cases, we may recommend CT or MRI.

Small Animal Ultrasound – UC Davis

Cancer Treatment Options for Pets

Every pet is different, and treatment depends on the type, location, and stage of the cancer—as well as your goals and your pet’s quality of life.

Surgery

Used to remove tumors when possible. This may be curative for benign or localized cancers.

Chemotherapy

Often used for systemic or aggressive cancers like lymphoma. Pets tolerate chemo much better than people, often with minimal side effects.

Radiation Therapy

Helps treat tumors that cannot be surgically removed, such as brain or nasal cancers.

Immunotherapy

Some cancers, like melanoma, respond well to vaccine-based treatments that help the immune system target abnormal cells.

Palliative Care

When cure isn’t possible, we focus on keeping your pet comfortable with pain management, appetite support, and tailored care.

Preventing Cancer in Pets: What You Can Do

While not all cancers are preventable, these steps can reduce your pet’s risk:

  • Routine checkups: Early detection is key
  • Spay/neuter: Reduces the risk of mammary and testicular cancers
  • Healthy diet & weight: Obesity is a risk factor for certain cancers
  • Avoid toxins: Keep pets away from secondhand smoke, pesticides, and unsafe household products
  • Limit sun exposure: Especially for light-skinned pets prone to skin cancer

Let Us Be Your Partner in Pet Health

Cancer is a frightening diagnosis, but you don’t have to face it alone. At Heartland Veterinary Hospital, we offer compassionate support, advanced diagnostics, and tailored treatments to help your pet live as comfortably—and as long—as possible.

If you’ve noticed any concerning changes in your dog or cat, don’t wait. Contact us today to schedule an exam.

Helpful Resources for Pet Owners