There are many opinions out there on when a dog should be desexed. Whilst shelters and councils promote early desexing to reduce unwanted pregnancies, many now believe delaying desexing can be beneficial.
As veterinarians we believe in science and as such we base our recommendations on the most recent evidence-based research around this issue. There is a LOT of information out there on this topic so we’ve tried to summarise it for you. Here are the facts:
FOR ALL DOGS:
- Many of the studies regarding desexing have looked at specific breeds and as such specific-breed recommendations are now considered. A great summary can be found in this investigation.
- Studies regarding age of desex and incidence of Hip Dysplasia vary in results and the latest suggest desexing has no effect on risk of hip dysplasia.
- Desexing doubles the risk of cranial cruciate ruptures in both male and female dogs but age at time of desex does not effect this incidence.
- Desexing doubles the risk of osteosarcoma tumours but age at time of desex does not effect this incidence.
- Desexing later than 6 months of age significantly increases their council registration fee in NSW.
- Desexing increases lifespans.
- Desexing reduces the risk of behavioural issues such as roaming, marking or inter-dog aggression.
FOR FEMALE DOGS:
- Desexing drastically reduces (99.5%) the risk of malignant mammary tumours when performed prior to their first oestrous (i.e. their first period). If performed before their second oestrous the risk is reduced by 92% but after the this the risk remains the same regardless of when desexing is performed.
- Desexing all but eliminates the risk of life-threatening uterine infections (called pyometra) that are common in entire female dogs.
- Female dogs desexed after 3 months old are less likely to develop urinary incontinence than those desexed prior to 3 months old.
- The occurrence of certain types of cancer including lymphoma, mast cell tumours and haemangiosarcomas were found to be higher in desexed females.
- Desexing eliminates the issue of dealing with a bitch on heat including bleeding, vocalising and confinement.
- A recent study showed that the absence of oestrogen in desexed females was associated with accelerated brain aging (i.e. more prone to “dementia”-type symptoms later on in life).
- Desexing mature female dogs is a much larger, more complicated surgery than puppies due to the reproductive tract being well developed and highly vascular leading to an increased risk of bleeding during and after surgery. Because of this mature female desexes are likely to cost significantly more than if the procedure was performed at 6 months old
FOR MALE DOGS:
- Desexing prevents testicular and epididymal disorders such as cancer, torsion or inflammation. Testicular cancer is common and often malignant in intact male dogs.
- Desexing male dogs prevents benign prostatic hyperplasia and inflammatory processes of the prostate.
- Desexing male dogs increases the risk of prostate cancer.
- For those male dogs exhibiting adverse behaviours e.g. intermale aggression, roaming, mounting or marking desexing earlier (e.g. 6 months) can reduce this behaviour and temperament should be a really important consideration when determining age to desex.
What we surmise from this information is that breed, sex and temperament play an important role in determining what age to desex as well as an owner’s financial limitations and these factors should be discussed with your vet to come up with an appropriate desexing age specific to your dog.
References
Gonadectomy in immature dogs: effects on skeletal, physical, and behavioural development.
Determining the optimal age for gonadectomy of dogs and cats.
Gonadectomy in Cats and Dogs: A Review of Risks and Benefits.
Factors influencing canine mammary cancer development and postsurgical survival
Association between ovariohysterectomy and feline mammary carcinoma.
Long-term risks and benefits of early-age gonadectomy in dogs.
A population study of neutering status as a risk factor for canine prostate cancer
Correlation of neuter status and expression of heritable disorders.
Canine ovariohysterectomy and orchiectomy increases the prevalence of ACL injury.
Host related factors for canine osteosarcoma
