My dog's testicles are suddenly much bigger. What could be wrong?

Swollen testicle can be due to torsion, allergic reaction or infection. i would recommend having it checked by your vet ASAP, if the swelling is too large you will need to take him to the emergencies if your vet is not open today.

I see that your dog is unneutered - one condition that can come on suddenly and be extremely painful is called testicular torsion. Basically, one of the testicles becomes twisted inside the scrotal sac, cutting off the blood supply and causing swelling and intense pain. Based on your description, I would be concerned about this possibility and would recommend getting your dog to a vet as soon as possible, since he is in a lot of distress and there is really nothing that can be done at home to help. Other possibilities would include a scrotal or testicular infection, a tumor, or even a scrotal hernia.

The picture does not show anything concerning but I would continue to monitor for any sweliing or discomfort which may indicate a painful infection or assymetry which can indicate a tumour. Rapid increase in size can occur with scrotal hernias which although rare are a surgical emergency.

This can be from an injury, infection or cancer. I expect this is painful also so please take Breezer in for an exam. They can feel the testicle, check him over to see if there are other problems then decide a course of treatment. With an infection or injury medication may heal this but if it's a tumor then having Breezer neutered may be recommended. I'm especially concerned since it is getting bigger daily so please take him in soon. Thanks for using Petco Pet Education Center, formerly Petcoach to help you care for Breezer.

Yes, your dog's testicles should be approximately the same size. One can be a tiny bit smaller, but there should not be a huge difference. Your dog needs to be seen by a veterinarian as he could have a testicular tumor, a testicular torsion, an abscess or orchitis or brucellosis. Please take him to a vet ASAP.

Thanks for using Petco Pet Education Center, formerly Petcoach! I am worried about this. I would advise that you go ahead and give a dose of the Benedryl and then get him into the vet as soon as possible- tonight with the ER vet is ideal. This could signal an allergic reaction, or a viral/bacterial infection. But I am most worried about something extremely painful such as a testicular torsion (where the testicle twists on itself, cutting of blood flow and causing swelling). If you can’t get to the vet tonight, ice the testicle for 5-10 minutes every 2-64hours to help with pain and swelling. Place a paper towel or thin cloth between the ice pack and his scrotum. Best wishes to you and Boi!

Your dog's testicles should have descended when he was a much younger dog. The fact that you're just noticing this now makes me very worried that something is wrong. He could have a torsion, mass, or infection. I would have him seen by a veterinarian as soon as possible. He may need to be neutered to resolve this issue.