At what age should you neuter a male dog

Some dog breeds have higher risk of developing certain cancers and joint disorders if neutered or spayed within their first year of life. Until now, studies had only assessed that risk in a few breeds. A new, 10-year study by researchers at the University of California, Davis, examined 35 dog breeds and found vulnerability from neutering varies greatly depending on the breed. The study was published in the journal Frontiers in Veterinary Science.

“There is a huge disparity among different breeds,” said lead author Benjamin Hart, distinguished professor emeritus at the UC Davis School of Veterinary Medicine. Hart said there is no “one size fits all” when it comes to health risks and the age at which a dog is neutered. “Some breeds developed problems, others didn’t. Some may have developed joint disorders but not cancer or the other way around.”

Researchers analyzed 15 years of data from thousands of dogs examined each year at the UC Davis Veterinary Medical Teaching Hospital to try to understand whether neutering, the age of neutering, or differences in sex when neutered affect certain cancers and joint disorders across breeds. The joint disorders examined include hip dysplasia, cranial cruciate ligament tears and elbow dysplasia. Cancers examined include lymphoma; hemangiosarcoma, or cancer of the blood vessel walls; mast cell tumors; and osteosarcoma, or bone cancer.

In most breeds examined, the risk of developing problems was not affected by age of neutering.

Breed differences by size and sex

Researchers found that vulnerability to joint disorders was related to body size.

“The smaller breeds don’t have these problems, while a majority of the larger breeds tend to have joint disorders,” said co-author Lynette Hart, professor at the UC Davis School of Veterinary Medicine.

One of the surprising exceptions to this was among the two giant breeds — great Danes and Irish wolfhounds — which showed no increased risk to joint disorders when neutered at any age.

Researchers also found the occurrence of cancers in smaller dogs was low, whether neutered or kept intact. In two breeds of smaller dogs, the Boston terrier and the shih tzu, there was a significant increase in cancers with neutering.

Another important finding was that the sex of the dog sometimes made a difference in health risks when neutered. Female Boston terriers neutered at the standard six months of age, for example, had no increased risk of joint disorders or cancers compared with intact dogs, but male Boston terriers neutered before a year of age had significantly increased risks.

Previous studies have found that neutering or spaying female golden retrievers at any age increases the risk of one or more of the cancers from 5 percent to up to 15 percent.

Discuss choices with veterinarians

Dog owners in the United States are overwhelmingly choosing to neuter their dogs, in large part to prevent pet overpopulation, euthanasia or reduce shelter intake. In the U.S., surgical neutering is usually carried out by six months of age.

This study suggests that dog owners should carefully consider when and if they should have their dog neutered.

“We think it’s the decision of the pet owner, in consultation with their veterinarian, not society’s expectations that should dictate when to neuter,” said Benjamin Hart. “This is a paradigm shift for the most commonly performed operation in veterinary practice.”

The study lays out guidelines for pet owners and veterinarians for each of 35 breeds to assist in making a neutering decision. Read the full list here.

Other authors include Abigail Thigpen with UC Davis School of Veterinary Medicine, and Neil Willits with the Department of Statistics in the UC Davis College of Letters and Science. Research support came from the Canine Health Foundation, the UC Davis Center for Companion Animal Health and Versatility in Poodles.

The decision whether or not to have your dog neutered can be daunting and there can be a lot of contradictory information available on the subject. We recommend that both male and female dogs are neutered (castrated for males and spayed for females) from four months of age on health grounds. We base this recommendation on the best scientific evidence available.

Male dogs 

The procedure involves removing your dog’s testicles under a general anaesthetic, which usually just requires your pet to be with us as a day patient. Castration will prevent your dog from being able to mate with a female dog, resulting in pregnancy, and it also may curtail undesirable behaviour. We also recommend that your pet is protected against lungworm before his surgery and we suggest applying Advocate treatment at least one month before his surgery is booked.

Benefits of neutering a male dog

• Eliminates the risk of your pet developing testicular cancer, which is the second most common tumour in male dogs. This is particularly important if your dog is found to have a cryptorchid (undescended) testicle. We also offer the option of Laparoscopic surgery (“keyhole” castration) for pets which suffer from abdominally retained testicles
• Neutering also protects your pet against prostatic diseases commonly seen in unneutered dogs including inflammation and overgrowth of the prostate gland.
• Unneutered dogs can be prone to developing hernias, in particular “perineal hernia” a painful condition which makes it very difficult for the sufferer to pass motions and requires specialist surgery to correct. Castrating your pet will prevent your pet from developing this condition.

Female dogs

The procedure involves removing your dog’s ovaries, or “ovariectomy” (OVE) under a general anaesthetic and this usually just requires your pet to be with us as a day patient. In the UK it is more traditional to remove the ovaries and womb, (“ovariohysterectomy” or OVH), however we prefer the OVE procedure as we believe it results in a quicker surgery with less damage to tissue. However, if during the surgery we find any abnormality of the womb, we will undertake a full OVH at no extra charge and it should be noted that this may be more likely in older pets.

Both OVE and OVH will result in your pet no longer coming into season or being able to have puppies and the OVE procedure confers the same health benefits as OVH. We also offer the option of laparoscopic ovariectomy (“keyhole” spay), which confers additional benefits for your pet .We also recommend that your pet is protected against lungworm before her surgery and we suggest applying Advocate treatment at least one month before the date or her surgery.

Benefits of neutering a female dog  

• Spaying your dog can reduce the chance of her developing mammary gland tumour (breast cancer), the most common type of malignant tumour in female dogs. This effect is directly associated with the timing of surgery, with the maximum protective effect achieved if your dog is spayed before her first season and it has been shown that this protective effect is reduced after the first season and with each subsequent season.
• Spaying your dog also eliminates the risk of your pet developing an infection of the womb (pyometra), a life-threatening condition that often requires emergency surgery when the patient is very ill. Pyometra is a very common condition and studies have shown that one in four unspayed female dogs will develop pyometra by the age of ten years old.
• OVE eliminates your pet’s chances of developing ovarian cancer.
• Although pregnancy and whelping are natural processes, just as with humans, things can go wrong and can be dangerous for your pet. Many dogs need assisted births, which can result in large veterinary bills. Neutering eliminates the risk of accidental pregnancy and its associated health risks and costs. It also avoids the necessity of finding homes for puppies, when shelter charities already have to deal with too many unwanted dogs. 
• Unspayed dogs will come into heat, which usually happens every six months. During this time she will be attractive to male dogs and will be pursued and harassed by them for up 10 days. Neutering will prevent your pet coming into heat and the inconvenience and difficulties of keeping her separate from male dogs.
• Once a female dog has had a season, she will go on to produce pregnancy hormones, whether she has been mated or not. This can result in her showing signs of false pregnancy ("pseudo-pregnancy”) about 8-9 weeks after her season which can include enlargement of her mammary glands, milk production and behaviour changes with nesting and sometimes aggression. Occasionally these signs can be severe and need veterinary treatment to resolve. Spaying will prevent your pet from developing pseudo-pregnancy

How much does dog spaying/neutering cost ?

Your pet spaying/neutering costs will vary according to the weight of your dog and the type of neutering involved 

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