Osteosarcoma in Dogs: Bone Cancer Causes, Symptoms & Treatment

Osteosarcoma is the most common form of bone cancer in dogs, a serious and aggressive disease primarily affecting large and giant breeds. Although it also occurs rarely in cats, it is uncommon, particularly in smaller dog breeds such as toy dogs. This guide will help you understand osteosarcoma, recognise early signs, and navigate treatment choices to support your beloved pet.

What is Osteosarcoma?

Osteosarcoma is a malignant tumour originating in the bone cells. It represents over 95% of bone tumours in dogs, growing rapidly and destroying bone tissue. It frequently develops in the long bones around joints like the shoulder, wrist, above the hock, and below the knee.

Which Dogs Are Most At Risk?

Large and giant breeds such as Great Danes, Irish Wolfhounds, German Shepherds, and Rottweilers are significantly more prone to osteosarcoma. While any dog can develop the cancer, these breeds' genetic predisposition and size contribute to higher susceptibility. Middle-aged dogs, typically between six to eight years old, are the most commonly affected.

What Causes Osteosarcoma?

The exact cause is unknown. Genetics appear to contribute, especially in larger breeds, but osteosarcoma is not considered strictly hereditary. Other possible risk factors include previous bone trauma, fractures, or infections. Environmental influences like radiation exposure might also play a role.

Recognising Symptoms of Osteosarcoma

Early symptoms can be subtle and easily mistaken for arthritis or injury. They include:

• Persistent lameness or limping
• Swelling or lumps near joints or bones
• Pain causing reluctance to move or play
• Behavioural changes such as irritability or lethargy
• Loss of appetite or weight loss

Regularly check your dog’s limbs for lumps or swelling and pay attention to any changes in mobility.

Diagnosing Osteosarcoma

Diagnosis requires a thorough veterinary examination. Imaging such as X-rays helps identify bone lesions and tumours. Additional tests might include blood work, biopsies, and bone scans to confirm malignancy and assess spread.

Treatment Options and Prognosis

While osteosarcoma is aggressive and challenging to cure, early intervention can prolong survival and improve quality of life. Treatment options include:

• Amputation of the affected limb, often combined with chemotherapy, which can halt local spread and ease pain. Despite the impact, many dogs adapt well to life with three legs and continue to enjoy active lives.
• Chemotherapy to target cancer cells, sometimes alongside surgery or as palliative care to manage symptoms.
• Radiation therapy for pain relief in some cases.
• Palliative care focussing on pain management and comfort when curative treatment is not possible.

The prognosis remains serious; osteosarcoma often spreads to lungs early. Typically, only around 10% of dogs survive beyond twelve months after diagnosis. Owners should prepare for lifestyle adjustments and close veterinary support.

Promoting Responsible Dog Ownership

Understanding osteosarcoma’s impact highlights the importance of regular veterinary check-ups, early symptom recognition, and making informed decisions about treatment and care. While the condition affects mostly large breeds, responsible breeding, health screening, and attentive pet care are key to supporting dogs' wellbeing.

Further Support

If your dog shows symptoms or receives a diagnosis of osteosarcoma, consult your vet promptly for a detailed assessment and discuss all treatment and care options to ensure the best possible outcome for your pet.