Neutering Male Dogs: Right Age, Benefits, and Recovery

What neutering involves

In a routine neuter, the vet removes both testicles through a small cut near the scrotum. The dog is under general anesthetic and receives pain relief during and after the operation. Most dogs go home the same day.

The scrotum is usually left in place, so at first it can look as if the testicles are still there. It shrinks over the following weeks. Two small swellings near the base of the penis, called the bulbus glandis, are normal glands. They can swell when a dog is excited and are sometimes mistaken for testicles.

There are alternatives. A hormone implant can switch off testosterone for a period of time without surgery, and its effects wear off. Some vets suggest it as a trial, to see how a dog's behavior changes before a permanent decision. Ask your vet whether it suits your dog.

The right age depends on size

For many years, most male dogs were neutered at around six months. Current guidelines are more tailored. The American Animal Hospital Association suggests about six months for dogs expected to weigh less than 45 pounds as adults. For larger dogs, it suggests waiting until growth stops, roughly 9 to 15 months of age.

The reason is the joints. Studies from the University of California, Davis, followed thousands of dogs and found breed and size differences. In mixed-breed dogs expected to weigh 20 kilograms, about 44 pounds, or more, neutering before one year was linked to more hip dysplasia, elbow dysplasia and torn cruciate ligaments. The risk was often up to three times that of dogs left intact. In mixed-breed dogs under 20 kilograms, no such increase was found. No rise in the cancers studied was seen in mixed-breed dogs of any weight group.

Breed matters too. In Labrador Retriever males, for example, joint disorders affected about 6 percent of intact dogs and about 13 percent of dogs neutered before six months. In a few breeds, early neutering was also linked to higher rates of some cancers. In many small breeds, the age of neutering made little difference to these risks. Very large breeds, such as Great Danes, finish growing late, so their owners may be advised to wait longer still.

Guidelines also say that other factors count. If later vet care is uncertain, or the dog lives where an unplanned litter is likely, earlier surgery may be the better choice. Your vet can weigh these points for your dog.

Health benefits

• Removes the risk of testicular cancer
• Lowers the risk of prostate enlargement and prostate infections later in life
• Lowers the risk of benign tumors around the anus, called perianal adenomas
• Lowers the risk of perianal hernias, a weakness in the muscles beside the anus
• Ends the chance of fathering unplanned litters

Dogs with an undescended testicle, called cryptorchidism, have a special reason to be neutered. Testicles normally drop into the scrotum within the first couple of months, and if one has not appeared by six months it is very unlikely to come down. A retained testicle has a much higher risk of becoming cancerous and can also twist, which can be life-threatening. The surgery is more involved, because the vet may need to search the groin or the belly, but it is strongly recommended. The condition is inherited, so affected dogs should not be bred.

Effects on behavior

Neutering mainly changes behaviors driven by testosterone. In a study of adult dogs neutered because of problem behavior, roaming, mounting and urine marking indoors improved by at least half in 60 percent or more of dogs. Fewer than a third of the dogs showed marked improvement in aggression, and fear of objects did not change. The dog's age at surgery did not predict how much he improved.

That means neutering is not a cure for aggression or fear. Some behavior is simply learned and continues after surgery. Testosterone can also give nervous dogs a little extra confidence. In some anxious or fearful males, neutering may make them more fearful or more likely to react when stressed. If your dog has a behavior problem, talk to your vet and a qualified behavior professional before deciding on timing. Our guide to dog aggression explains where to start.

A confident, well-socialized dog is very unlikely to change in personality. He will still play, learn, guard the house and love his family.

Surgery day

Your vet will tell you when to stop food, usually the evening before. Water is often allowed until a few hours before surgery. Follow your own clinic's instructions, because they vary. Tell the team if your dog has been unwell recently or is taking any medicines.

At the clinic, the vet examines your dog, and many clinics run a blood test before the anesthetic. Your dog will have a sedative and pain relief, then the anesthetic. Most dogs come home later the same day, still a little sleepy.

Recovery at home

Most dogs feel better within a day or two, but the wound needs rest to heal. Plan for 7 to 10 days of quiet time.

• Give him a warm, quiet place to rest on the first night, away from children and other pets.
• Offer a small meal that evening. Some dogs skip a meal after surgery, and that is usually fine.
• Use a cone or a recovery suit to stop him licking or chewing the wound, usually for 7 to 14 days.
• Keep him on a leash for short toilet walks only. Avoid running, jumping, stairs and rough play.
• Do not bathe him or let him swim until your vet says the wound has healed.
• Check the wound a few times a day.
• Go to every follow-up visit. Stitches that do not dissolve are usually removed 7 to 14 days after surgery.

Call your vet if you notice any of the following.

• Bleeding or discharge from the wound
• Redness or swelling of the wound or the scrotum
• A wound that opens, or missing stitches
• Not eating 24 hours after surgery
• Vomiting, diarrhea or trouble passing urine
• Weakness, being unable to stand, or low energy that lasts more than two days
• Signs of pain that do not settle with the medicine your vet gave

Weight after neutering

Neutered dogs need fewer calories than intact dogs, often about 30 percent fewer. If you keep feeding the same amount, weight creeps up. Weigh your dog every few weeks after surgery, adjust portions with your vet's help, and keep up daily exercise once he has healed. In a large study of Labrador Retrievers in the UK, overweight was more common in neutered males than in intact males. See our guide to overweight dogs and cats for practical tips.

Common myths

• "He should father one litter first." There is no evidence that breeding benefits a male dog.
• "Neutering will make him lazy and fat." Weight gain comes from too much food and too little exercise, which you can control.
• "He will lose his personality." Well-socialized dogs keep their character.
• "It will fix every behavior problem." It helps behaviors driven by hormones, such as roaming and marking, much more than fear or aggression.
• "He is too old." Neutering older dogs is generally safe, and it can still protect against prostate and testicular problems. Your vet will check his health first.

Neutering and rescue dogs

Unneutered males roam in search of females, and roaming dogs are more likely to be hit by cars, hurt in fights or lost. Every unplanned litter also needs homes, and not every puppy finds one. At Paw Squadron, every dog we rescue sees a vet and is dewormed. If you adopt a male dog who is not yet neutered, ask your vet about the right age and method for his size and breed. For the female side of the same decision, read our guide to spaying female dogs, and for joint problems in large dogs, see hip dysplasia.

Find more practical guides in PawPedia, or read our FAQ for questions about adopting from us.