Lymphoma in dogs: causes, symptoms and treatment guide

Lymphoma, or lymphosarcoma, is a common cancer in dogs affecting white blood cells called lymphocytes that spread through organs like the lymph nodes, spleen, bone marrow and liver. It represents up to 24% of all canine cancers diagnosed in the UK, highlighting its prevalence and the importance of awareness and early detection.

What causes lymphoma in dogs?

Lymphoma typically arises due to genetic risk factors inherited through a dog’s bloodline. A family history of lymphoma increases the risk, but environmental factors, such as exposure to toxins or pesticides, may also contribute to lymphoma development, even in dogs without ancestral history.

Which dogs are at risk of lymphoma?

While any dog can develop lymphoma, risk tends to increase from middle age onwards, generally from seven years of age, and even earlier in some giant breeds. Certain breeds have higher susceptibility, including:

• Basset Hound puppies
• Scottish Terrier puppies
• Bulldog puppies
• Boxer puppies
• Bull Mastiff puppies
• Airedale Terrier puppies
• Dachshund puppies
• Pomeranian puppies
• Chow-Chow puppies
• German Shepherd puppies
• Rottweiler puppies
• Golden Retriever puppies

Among these, Golden Retrievers are particularly at high risk, with estimates suggesting up to one in eight may develop lymphoma in their lifetime. Dachshunds and Pomeranians, while still at risk, have comparatively lower rates.

The types and stages of lymphoma in dogs

Lymphoma is classified into stages that reflect the extent and severity of cancer spread:

• Stage one: Cancer affects a single lymph node.
• Stage two: Regional lymphoma affecting lymph nodes on one side of the diaphragm.
• Stage three: Generalised enlargement of most or all lymph nodes.
• Stage four: Liver and spleen involvement, potentially alongside lymph node enlargement.
• Stage five: Advanced disease affecting bone marrow, nervous system, and other organs.

Understanding the stage is vital for prognosis and treatment planning.

The role of lymph nodes

Lymph nodes, or lymph glands, are crucial parts of the immune system. They are spread throughout a dog’s body, commonly found in the neck, armpits, abdomen, and limbs. Lymph nodes filter lymphatic fluid and help fight infection. Enlargement of these nodes is often the first sign of lymphoma.

Recognising symptoms of lymphoma in dogs

Early recognition can improve outcomes. Symptoms vary depending on lymphoma location but can be general or localised:

• Loss of appetite and weight loss
• Recurrent vomiting or digestive upset
• Lethargy and depression
• Painless swelling of lymph nodes
• Fever
• Increased thirst and urination
• Thinning or loss of coat

Lymphoma spread to lungs may cause coughing and breathing issues, while gastrointestinal lymphoma may lead to bloody stools or persistent digestive problems. Symptoms affecting skin, eyes, or nervous system vary and require veterinary diagnosis.

How is lymphoma diagnosed?

Your vet will use a combination of techniques such as:

• Fine needle aspiration or biopsy of lymph nodes or affected tissues
• Blood and urine tests
• X-rays and ultrasound scans
• Bone marrow biopsies for advanced cases

Timely diagnosis is crucial for beginning treatment and managing the disease.

Treatment options and outlook

Lymphoma is aggressive, but treatment can improve quality of life and extend survival. Without treatment, average survival is about two months. Chemotherapy is the most common treatment, sometimes achieving remission especially for early stages. Prednisone may be used to reduce symptoms but is generally not a standalone cure.

While a full cure is rare, chemotherapy can add years of comfortable life with good veterinary care and regular monitoring. Early veterinary intervention is key to providing your dog with the best chance of a good quality of life during treatment.

Supporting your dog with appropriate nutrition, pain management, and emotional care during treatment promotes their wellbeing. Always consult your vet for personalised guidance and to discuss the best treatment path for your dog's specific condition.