Updated July 28, 2022
Whether you call it neuter, spay, castrate or desex, the right time to get it done in dogs is a subject of much debate. This is because it varies from breed to breed. Recently, a study was published on the best age for neutering in Chihuahuas.
While the paper isn’t perfect (more on that later), it does provide the first evidence for Chihuahuas on choosing a time of desexing with the fewest health problems. The study compared dogs neutered at different ages for their rates of:
- hip dysplasia (HD), cruciate ligament injury (CCL) and elbow dysplasia (ED)
- lymphoma (LSA), mast cell tumour (MCT), haemangiosarcoma (HSA), osteosarcoma (OSA)
- urinary incontinence (UI)
All of these have been suspected to be linked with the age of neutering. Here’s what they found (only bold values are significant, my summary to follow):
| HD | CCL | ED | At Least One | |
| Male < 6 months | 0/26 (0) | 0/26 (0) | 0/26 (0) | 0/26 (0) |
| Male 6 – 11 months | 0/65 (0) | 1/65 (1.54) | 0/65 (0) | 1/65 (1.54) |
| Male 1 year | 0/37 (0) | 1/37 (2.7) | 0/37 (0) | 1/37 (2.7) |
| Male 2 – 8 years | 0/55 (0) | 1/55 (1.82) | 0/55 (0) | 1/55 (1.82) |
| Male Intact | 0/261 (0) | 0/261 (0) | 0/261 (0) | 0/261 (0) |
| Female < 6 months | 0/24 (0) | 0/24 (0) | 0/24 (0) | 0/24 (0) |
| Female 6 – 11 months | 0/78 (0) | 1/78 (1.28) | 0/78 (0) | 1/78 (1.28) |
| Female 1 year | 0/71 (0) | 0/71 (0) | 0/71 (0) | 0/71 (0) |
| Female 2 – 8 years | 0/106 (0) | 0/106 (0) | 0/107 (0) | 0/105 (0) |
| Female Intact | 1/297 (0.34) | 0/298 (0) | 0/297 (0) | 1/296 (0.34) |
| LSA | MCT | HSA | OSA | At Least One | |
| Male < 6 months | 0/26 (0) | 0/25 (0) | 0/26 (0) | 0/26 (0) | 0/25 (0) |
| Male 6 – 11 months | 1/63 (1.59) | 2/65 (3.08) | 0/65 (0) | 0/65 (0) | 3/63 (4.76) |
| Male 1 year | 0/37 (0) | 0/37 (0) | 0/37 (0) | 0/37 (0) | 0/37 (0) |
| Male 2 – 8 years | 0/55 (0) | 0/55 (0) | 0/55 (0) | 0/55 (0) | 0/55 (0) |
| Male Intact | 4/261 (1.53) | 4/261 (1.53) | 0/261 (0) | 0/261 (0) | 8/261 (3.07) |
| Female < 6 months | 0/24 (0) | 0/24 (0) | 0/24 (0) | 0/24 (0) | 0/24 (0) |
| Female 6 – 11 months | 0/77 (0) | 2/78 (2.56) | 0/78 (0) | 0/78 (0) | 2/77 (2.6) |
| Female 1 year | 0/71 (0) | 0/71 (0) | 0/71 (0) | 0/71 (0) | 0/71 (0) |
| Female 2 – 8 years | 0/106 (0) | 1/106 (0.94) | 0/107 (0) | 1/107 (0.93) | 2/105 (1.9) |
| Female Intact | 0/293 (0) | 2/299 (0.67) | 0/297 (0) | 0/298 (0) | 2/294 (0.68) |
UI was not reported in any of the spayed females.
If this table makes no sense, it’s mostly because there are no abnormal findings. Have a look at this one for Golden retrievers as a comparison.
Summary: The Best Chihuahua Spay & Neuter Times
There is minimal evidence that Chihuahua health problems are influenced by the age of neutering. Owners of either sex are therefore free to choose the age of desexing that suits them best.
What of the widespread belief that Chihuahuas need to be a minimum size before neutering? My strong view is that this is secondary to hypothermia under anaesthesia, and can be counteracted by effective warming devices such as the Bair Hugger.
Recommendation: 6 months for both sexes.
This is so far the only science we have for the best desexing age in Chihuahuas. Your vet, breeder or online group may have a different opinion based on their experience or personal beliefs. It’s perfectly reasonable to take their advice into consideration as well.
Problems With This Study
The authors do not mention the well-known increase in lifespan associated with desexing male and female dogs, which tends to counteract most concerns about specific cancers. The following comment in the paper is a clue that it might also have been true for this population:
Across all breeds the mean age of last entry in the record for neutered males was 5.5 years (range 3.71–6.54), for neutered females 5.7 years (range 4.21–6.97), for intact males 4.9 (range 4.15–7.11), and intact females 4.7 (range 3.41–6.32)
The study tries to also look at the rates of mammary cancer & pyometra in females, but cannot give an accurate assessment for two reasons:
- the mean ages listed above are far too young to pick up most cases
- pyometra and mammary cancer are rarely referred to university hospitals
Regardless of any concerns, the authors are to be applauded to bringing into focus one of the most common questions from dog owners. For the Chihuahua at least, they’ve made the decision a lot easier.
Related: Best Desexing Age For 35 Breeds | Desexing Choices For Dogs | Costs Of Desexing
Have something to add? Comments (if open) will appear within 24 hours.
By Andrew Spanner BVSc(Hons) MVetStud, a vet in Adelaide, Australia. Meet his team here.
I’m aquiring a Chihuahua that will be approximately 3.5 lbs when grown and have been told by the breeder to wait until he is six to eight months old to neuter. The web sites I have read say 2 to 3 lbs is necessary to withstand neutering and I’m hoping the weight will be at least three lbs at the correct age. I’m also hoping I can catch him before he starts to mark in my house! Your information was very helpful!
Hi Jessie. I strongly believe that such folk wisdom relates to deaths from hypothermia. In our clinic we are not concerned about body weight, but to be this way we have to be uncommonly fastidious about maintaining body TEMPERATURE. Choose a vet that uses a Bair Hugger device or equivalent (most or all now do).
This article has helped me so, so much. My chi puppy, Mango, turns five months tomorrow and he is getting neutered next month. I signed a six month neuter contract, so I had no choice, but I feel a lot better after I’ve read the data. I just want my baby to have a long and healthy life. He’s my ESA and he deserves the world.
I had my last chi neutered at around 2.5 years old and he lived to about 15.5 years old. He developed all the common joint issues that a lot of chis do, along with glaucoma and dental issues between 10-15 years old. I recently got 2 new chi puppies and have started to question when to get it done, I’m leaning towards 3 years because chis aren’t considered seniors until 10. I really want my chis to live the longest and healthiest lives they can. I hope they add lifespans related to neutering to another study!
Hi Kat. You can actually see the link between lifespan and neutering here. Short answer: significant benefit for females, marginal benefit for males.
Large dogs growth plates are fully developed around 2-2.5 yrs and for small dogs such as yorkies and chihuahuas they are fully developed at 1-1.5 yrs. I plan on getting my chi spayed between 12-18 months… This should give her time to accumulate all the heathy hormones she needs for a long, healthy life.
Hi Jayde. You are correct that the final age for full closure of all growth plates is likely to be as you mention. You’re welcome to wait until these ages, but there is no evidence that doing so will have any extra benefit, and there are disadvantages with later neutering to consider. It’s always worth remembering that growth occurs on a curve, not a straight line, with the vast majority occurring in Chihuahuas before six months of age.