What are the pros and cons of neutering?

“In my busy clinic, we neuter between two and six dogs every day; neutering is among the most common operations we perform. Many internet dog groups have nothing good to say about neutering, so why do vets recommend it?

“Rescue organisations recommend neutering to prevent unwanted litters. Unfortunately, we still see several unplanned litters in our clinic every year. Usually, the mismating happens between dogs living in the same house, because people underestimate the lengths dogs will go to in order to mate — climbing out of pens, even opening doors! Owners often request neutering to prevent behavioural problems, especially in male dogs.

“There seems to be a concern that adult, entire male dogs will become aggressive, both with dogs and people. Behaviour does change when a male dog reaches adolescence, but, if properly managed, testosterone-driven aggression is relatively rare. Dogs go through swings in testosterone levels, which make their behaviour very changeable: one day they have high testosterone, and want to challenge other dogs, sniff for bitches, and may forget their training, but a few days later their testosterone might plummet, leaving them fearful of older dogs and new experiences.

“During adolescence it is important to adapt your training and socialisation depending on your dog’s state of mind. Allowing him to practise sizing up to other dogs could lead to aggressive encounters, and you might need to use the lead more often to restrict his desire to wander off after female dogs. Adult, entire male dogs do tend to urine mark more frequently on walks, but confident dogs aren’t likely to urinate indoors.

“Owners often ask if neutering their dog (of either sex) will calm it down. The answer is not really! Bouncy dogs tend to stay bouncy after neutering, and there is no evidence that working dogs lose their drive. Fearful dogs should not be neutered and help should be sought from a behaviourist. Bitch owners may worry about exercising when their dogs are in season, and about the mess they might make. In my experience, most bitches keep themselves fairly clean, but exercise may be limited.

“Vets tend to be most concerned with the health benefits of neutering, though these may not be as clear cut as once thought. Removing the testicles prevents diseases associated with them, including testicular cancer and torsion, but also reduces the risk of diseases promoted by testosterone, including perianal tumours and perineal hernias.

“Most entire males over six years old will have some degree of benign prostate enlargement (caused by benign prostatic hyperplasia or BPH), but this rarely causes symptoms. If your dog shows signs, such as difficulty in passing faeces, and is diagnosed with BPH, there are medical options as well as castration. Prostate tumours are slightly more common in neutered male dogs, but overall it remains a rare disease.

“Neutering dogs before puberty causes the growth plate in the long bones to close later, and this can lead to altered joint angles as well as taller dogs. There is a correlation between neutering and cruciate rupture in some large breeds, but factors including conformation, weight, and lifestyle could have an influence as well as neutering.

“Castration is always advised where dogs have testicles retained in the abdomen at over six months old, because the risk of testicular tumour is greatly increased.

Greater benefits of neutering dogs

“In female dogs, the health benefits of neutering are slightly greater. Entire bitches can develop phantom pregnancies after seasons; most cases are mild but some require medical treatment.

“Data from Sweden (where routine neutering is banned) suggests 25 per cent of bitches over the age of 10 will develop pyometra. This is a life-threatening condition where the womb fills up with pus, leading to sepsis. Treatment is by emergency surgery, or occasionally medical treatment, followed by surgery. Mammary tumours are more common in entire female dogs, with the risk rising significantly after the second season. Urinary incontinence is commonly seen in neutered females. Large breeds are more often affected, especially if spayed later in life.

“Overall, neutered dogs appear to live longer, however this could reflect a difference in lifestyle as much as the influence of hormones. Cancer is a bigger cause of death in neutered pets, perhaps because of their greater age. However, there is a significant increase in risk for osteosarcoma (bone tumours) in some breeds. Rottweilers may be twice as likely to develop osteosarcoma if neutered, and this breed already has a high incidence of the disease.

“There is no easy answer to the ‘should I neuter my dog, and at what age?’ question. In my clinic, we offer neutering for bitches at six months for small breeds, but recommend waiting until three months after the first season for larger or active breeds. We always suggest neutering bitches over seven. We neuter males from the age of six months, but, again, prefer to leave larger or active breeds until they are 12 to 18 months old.”

Neutering options for dogs

• Castration/ orchidectomy: Both testicles removed. Hormone levels drop after four to six weeks and male behaviours reduce.
• Vasectomy: The vas deferens, which transports sperm from the testicles to the urethra, is cut and tied off. This is an uncommon procedure in the UK and only makes the dog infertile. It doesn’t stop any male behaviours, including the desire to mate.
• Hormone implant: Six- or 12-month implants are available to block the production of testosterone. They reduce fertility after six weeks, and male behaviours usually reduce. Aggression can increase in the first weeks.

Neutering options for bitches

• Spay/ovariohysterectomy: The most common version performed in the UK. The ovaries and uterus are removed through a midline incision. Full recovery takes up to six weeks, but most bitches are acting normally after two to three days with good pain relief.
• Ovariectomy: Just the ovaries are removed, either through a midline incision, or by a laparoscopic (keyhole) technique. There is no risk of pyometra or uterine tumour, and no increased risk of mammary tumours if the whole ovary is removed. Reports suggest a faster initial recovery from laparoscopic spays, but full recovery still takes up to six weeks.
• Ovary sparing spay/tubal ligation: Very uncommon in surgeries in the UK. Like vasectomy, they only cause infertility and don’t have any of the other benefits of neutering. Anaesthetic time and surgical risk would be similar to other neutering operations.
• Medications: drugs are available to delay or stop seasons, but are used infrequently now due to their potential side effects, which include mammary tumours, pyometra, and failure of fertility to return after treatment ends.