Dog Testicular Cancer Symptoms: What to Know

A testicular tumour may present as one testicle becoming larger, firmer, or uneven compared with the other. A dog may also have scrotal swelling, discomfort, skin changes, reduced fertility, or hormonal changes such as hair loss and darker skin. An undescended testicle can be located in the groin or abdomen rather than the scrotum. Infection, trauma, twisting, fluid, and other non-cancerous conditions can cause similar findings, so appearance does not establish a diagnosis.

Book a veterinary appointment for any new testicular change, scrotal swelling, or unexplained hormonal sign. Note when it began, whether it is painful, and whether the dog has an undescended testicle. The veterinarian may examine the abdomen and groin, perform ultrasound, and recommend blood tests or removal for laboratory analysis. [Testicle Removal Surgery](/treatments/surgical-oncology/orchidectomy/) is a common treatment discussion; [Chemotherapy](/treatments/systemic-therapy/chemotherapy/) or [Radiotherapy](/treatments/radiation-oncology/radiotherapy/) may be considered for selected findings. If future biological parenthood matters, ask about [Fertility Preservation](/treatments/fertility-and-assisted-reproduction/fertility-preservation/) before treatment.

Seek urgent veterinary care for sudden severe scrotal or abdominal pain, rapid swelling, repeated vomiting, collapse, inability to urinate, or marked weakness. Sudden pain can indicate twisting or another emergency that needs prompt treatment, whether or not a tumour is present.

Ask whether both testicles are in the scrotum, what the examination and ultrasound show, and whether removal is recommended. Discuss laboratory testing, recovery, hormone-related signs, fertility considerations, and whether further treatment or monitoring will be needed.