Age To Spay Or Neuter, Ovary Sparing Spay, Vasectomy, Cancer Links

heart murmur in dogs

What’s the ideal age to spay or neuter a puppy? I recently read an article that indicated that doing it too early can lead to serious hormonal and health problems because of the way the procedure is performed on dogs. Alternatively are there vets that are qualified to do a tubal ligation in Canada as opposed to the typical spaying methods?

~ Christina

Dr Sara Chapman

Dear Cristina,

This is a very good question. Our knowledge about the issues surrounding neutering is increasing, as more studies examine disease incidence in neutered and non-neutered (intact) animals. We are realizing that surgical removal of the gonads (gonadectomy) – spaying or ovariohysterectomy in females, and castration in males – is not the universally benign procedure that veterinarians and pet owners have believed.

A study in February 2013 compared the incidence of joint disease and cancers in Golden Retrievers.

This generated a lot of discussion in the veterinary world, and a very good summary appeared in the Journal of the American Veterinary Medical Association.

There have been numerous other studies exploring the link between neutering and disease incidence. Dr. Root Kustritz, a prominent reproductive specialist, published literature reviews in 2007 and 2012, examining this issue.

She summarizes the advantages and disadvantages as follows:

Advantages of gonadectomy include decrease in reproductive tract disease, including pyometra and mammary neoplasia in bitches and queens, and testicular neoplasia and prostate disease in male dogs. Other advantages include: decrease in pregnancy and parturition-related disorders including metritis, mastitis and dystocia; decrease in hormone-associated disorders such as vaginal prolapse in bitches and mammary hypertrophy in queens; and decrease in undesirable sexual behaviours. Disadvantages of gonadectomy include surgical and anaesthetic complications, increased risk of neoplasia of various organ systems, increased incidence of some musculoskeletal and endocrinologic disorders, obesity and urinary incontinence in bitches.

How, then, does this affect my sterilization recommendations for dogs? It is very important that all dogs which are not intended for breeding should not be bred. Animal shelters may try to prevent this with early gonadectomy, yet as we have seen, there are negative health effects of this practice. The best option is to sterilize animals, while still retaining their gonads and sex hormones. This is not routinely done, though the Parsemus Foundation has information about these procedures, including a list of vets who offer these options.

For bitches, the ideal procedure is an ovary sparing spay. This surgery removes the entire uterus and cervix, leaving the ovaries. The bitch can then no longer become pregnant or develop uterine diseases. A tubal ligation should never be performed on a female dog. Elderly bitches have an up to 25% incidence of pyometra (uterine infection) a life-threatening disease. Intact female dogs, unlike humans, have progressive thickening of the uterine wall as they age, due to repeated stimulation by progesterone; this is why bitches develop pyometra and people don’t. That is why any sterilization procedure in bitches which allows the bitch to retain her ovaries must include removal of the entire uterus, to prevent pyometra later in life.

Bitches spayed in this way will still act like they are in heat (flagging, being lovey, and permitting mounting), and they will be attractive to males, but there will be no significant vaginal discharge. My own Bernese Mountain Dog bitch had an ovary sparing spay at 5 years of age. I did not intend to breed this bitch again, and I wanted to eliminate her risk of pyometra, a serious problem of older Berner bitches. It was particularly important to me that my bitch retain her ovaries, as Berners have a high incidence of cancer, like Goldens. The surgery is no more difficult than a conventional spay, just a little different, requiring complete removal of the cervix. The practice owner where I consult, Dr. Sue Maturo, performed the surgery. My girl recovered beautifully from the surgery.

I have also had a young male Bernese Mountain Dog vasectomized, so that he could retain the beneficial effect of the sex hormones on his bone / joint development. This pup was not acceptable for breeding purposes, so I wanted to ensure that he was sterile. It was not a difficult surgery, though more involved than a castration, as care was required to isolate and ligate the vasa. This surgery was performed by a theriogenologist (reproductive specialist) The pup’s recovery was quicker than from a conventional neutering. He is now an adult, and like most intact males that are properly trained and handled, he has no behaviour problems, and his owner does not have to worry that he could cause an unwanted pregnancy.

It may not be possible or practical for everyone to have these procedures performed on their dogs. In such cases, the Golden Retriever study referenced above indicated that spaying or castrating after sexual maturity – at least one year for small breeds, up to two years of age for large and giant breeds – was associated with a decrease in joint problems and some decreased cancer incidence compared to dogs neutered before puberty.

In conclusion, I would urge all pet owners to seek out vasectomy or ovary sparing spay for their dogs, if at all possible. If this is not possible, please wait until after sexual puberty to neuter your dogs. For bitches, wait at least two months after a heat cycle, and at least one month before the next cycle is expected. This will ensure that the procedure is performed during the diestrus period, when hormonal influence is the lowest.

S.F. Chapman DVM, MRCVS, VetMFHom

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