Science Hound

inloversmeeting asked: I don't know if you've talked about this before, but I've been struggling to parse through information on juvenile spay/neuters in dogs - I know shelters push for it for population control and I've seen a number claim that there are no long term physiological or behavioural effects, but I've also seen quite a few people I know in the dog world argue that juvenile sterilization doesn't allow them to fully develop. do you have any resources regarding this that you could share?

snootsprite:

dogs-on-logs:

thelazypetowner:

pawsitivelypowerful:

Yes! Here’s two links to two studies done by UC Davis. One done on GSDs and one on Golden Retrievers.(Click the breed names for the links).

And here’s another article that sites sources at the bottom. Link.

Here are the ones I have.

- Reproductive Capability is Associated with Lifespan and Cause of Death in Companion Dogs: http://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0061082
- Early Spay-Neuter: Clinical Considerations: http://www.tc.umn.edu/~rootk001/early_spay_neuter_article.pdf
- Early-age neutering of dogs and cats in the United States (a review): https://www.ncbi.nlm.nih.gov/pubmed/11787153
- Gonadectomy effects on the risk of immune disorders in the dog: a retrospective study: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5146839/
- Early Spay-Neuter Considerations for the Canine Athlete: One Veterinarian’s Opinion: http://www.caninesports.com/uploads/1/5/3/1/15319800/spay_neuter_considerations_2013.pdf
- Neutering Dogs: Effects on Joint Disorders and Cancers in Golden Retrievers: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0055937
- Neutering of German Shepherd Dogs: associated joint disorders, cancers and urinary incontinence: http://onlinelibrary.wiley.com/doi/10.1002/vms3.34/full
- Determining the optimal age for gonadectomy of dogs and cats: https://www.avma.org/News/Journals/Collections/Documents/javma_231_11_1665.pdf
- Long-term outcome of gonadectomy performed at an early age or traditional age in dogs: https://www.avma.org/News/Journals/Collections/Documents/javma_218_2_217.pdf
- Effect of gonadectomy on subsequent development of age-related cognitive impairment in dogs: https://www.avma.org/News/Journals/Collections/Documents/javma_219_1_51.pdf
- Long-Term Health Effects of Neutering Dogs: Comparison of Labrador Retrievers with Golden Retrievers: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0102241
- The Spay/Neuter Controversy and Topics in Genital Surgery: http://vetfolio.s3.amazonaws.com/bc/1d/831cd1f54b539492b4855b811b2e/the-spay-neuter-controversy-and-topics-in-genital-surgery-pdf.pdf
- Long-term risks and benefits of early-age gonadectomy in dogs: https://www.avma.org/News/Journals/Collections/Documents/javma_224_3_380.pdf
- Long-Term Health Risks and Benefits Associated with Spay / Neuter in Dogs: https://www.researchgate.net/publication/237315791_Long-Term_Health_Risks_and_Benefits_Associated_with_Spay_Neuter_in_Dogs
- Mammary Tumors in Dogs: http://www.veterinarypartner.com/Content.plx?A=1350
- A retrospective study of pyometra at five RSPCA hospitals in the UK: 1728 cases from 2006 to 2011: http://veterinaryrecord.bmj.com/content/173/16/396
- Breed variations in the occurrence of pyometra and mammary tumours in Swedish dogs: http://www.ivis.org/proceedings/iscfr/2012/74.pdf?LA=1
- Breed risk of pyometra in insured dogs in Sweden: http://onlinelibrary.wiley.com/doi/10.1111/j.1939-1676.2001.tb01587.x/abstract

Correlation of neuter status and expression of heritable disorders (2017) - 90,090 dog health records:

https://www.researchgate.net/publication/317284794_Correlation_of_neuter_status_and_expression_of_heritable_disorders

An update on the risks and benefits of neutering in dogs (2018) https://www.magonlinelibrary.com/doi/abs/10.12968/vetn.2018.9.3.150

Slightly related since many tumblr ppl seem concerned about hips because of a couple of studies:

Effect of a commercially available fish-based dog food enriched with nutraceuticals on hip and elbow dysplasia in growing Labrador retrievers https://www.researchgate.net/publication/324543059_Lavoro_Canadian_Antonella_Volta

I did neuter research for another forum but I’ll repost it here.  Some of these might’ve been posted already but I’m going to keep them since I had comments on them and the primary research links to the abstracts. I hate paywalls and I hate that I couldn’t evaluate each study thoroughly (no I’m not paying $30-$50 to rent a paper for 24 hrs).

Warning: This is very long and not my area of expertise, so I have no idea how credible these labs are or the journals the research is printed in. I also don’t have access to the articles themselves so I can’t tell you if the conclusions they draw in the abstract are accurate for the data they presented in the paywalled article. Not all the papers state their n or define neuter status as early/late/etc.

BEHAVIORAL EFFECTS

The influence of breed and environmental factors on social and solitary play in dogs (Canis lupus familiaris).
https://www.ncbi.nlm.nih.gov/pubmed/28702755
Claimed that mixed groups of neutered/intact dogs played more than neutered-only or intact-only groups. Surprising result to me, no n listed.

Age, sex and reproductive status affect boldness in dogs.
https://www.ncbi.nlm.nih.gov/pubmed/23778256
In Australian dogs: Males bolder than females, young bolder than old, intact bolder than neutered.

Factors associated with canine resource guarding behaviour in the presence of dogs: A cross-sectional survey of dog owners.
https://www.ncbi.nlm.nih.gov/pubmed/28274585
Neutered males more likely to display resource guarding aggression. n=3068

Mandatory desexing of dogs: one step in the right direction to reduce the risk of dog bite? A systematic review.
https://www.ncbi.nlm.nih.gov/pubmed/28130398
Neutering reduces risk of dog bites.

Effect of gonadectomy on subsequent development of age-related cognitive impairment in dogs.
https://www.ncbi.nlm.nih.gov/pubmed/11439769
2001 study, small n. Intact males had slower progression of cognitive impairment compared to neutered males.

Risk factors for canine cognitive dysfunction syndrome in Slovakia.
https://www.ncbi.nlm.nih.gov/pubmed/26927954
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4772312/
2016 study, small n (~200). Claims diet, size, and age more important to canine cognitive dysfunction syndrome.

Prevalence and risk factors of behavioural changes associated with age-related cognitive impairment in geriatric dogs.
https://www.ncbi.nlm.nih.gov/pubmed/19200264
2009, small n (325). Female and neutered dogs worse off than male and intact dogs. Smaller dogs more likely to show age-related impairment.

Length of time domestic dogs (Canis familiaris) spend smelling urine of gonadectomised and intact conspecifics.
https://www.ncbi.nlm.nih.gov/pubmed/28689817
Neutered dog pee is confusing to tester dogs and they sniff it longer. I can’t believe this got funding.

PHYSICAL EFFECTS

***Correlation of neuter status and expression of heritable disorders.***
https://www.ncbi.nlm.nih.gov/pubmed/28560045
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5445488/
Good review of neutering risks and benefits. It also had many references to follow up in their paper. Neutering increased risk for certain cancers, ruptured anterior cruciate ligament, epilepsy, etc. Neutering decreased risk for some congenital conditions. N over 90k

Neutering dogs: effects on joint disorders and cancers in golden retrievers.
https://www.ncbi.nlm.nih.gov/pubmed/23418479
Hip dysplasia doubled in neutered males (10%), CCL seen in neutered animals (5% males, 8% females) but not intact animals, 10% neutered males had lymphosarcoma (3x higher than intact males), hemangiosarcoma 8% in late-neutered females (4x higher than intact or early-neutered female), mast cell tumors in 6% in late-neutered females. N=759

The role of neutering in cancer development.
https://www.ncbi.nlm.nih.gov/pubmed/25174910
Brings up point that cancer findings may be breed specific, also societal issues related to pet overpopulation occur means we need neutering available as an option.

Gonadectomy effects on the risk of immune disorders in the dog: a retrospective study.
https://www.ncbi.nlm.nih.gov/pubmed/27931211
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5146839/
Sex steroids are important for immune function! Neutering increased risks of atopic dermatitis, autoimmune hemolytic anemia, hypoadrenocorticism, hypothyroidism, immune-mediated thrombocytopenia, inflammatory bowel disease. They also discussed how you can induce a lot of these diseases in mouse models by removing the gonads. N is over 90k again

Long-term health effects of neutering dogs: comparison of Labrador Retrievers with Golden Retrievers.
https://www.ncbi.nlm.nih.gov/pubmed/25020045
Neutering increased cancer rates and joint disorders in labs and goldens. Cancer increase was worse in neutered female goldens.

Neutering of German Shepherd Dogs: associated joint disorders, cancers and urinary incontinence.
https://www.ncbi.nlm.nih.gov/pubmed/29067194
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5645870/
Joint disorders - Intact males 7%, neutered males 21%, intact females 5%, neutered females 16%. Mammary cancer higher in intact females 4% compared to neutered females 1%. Urinary incontinence found in 7% of neutered females, not found in intact females. N = 1170

Gonadectomy in immature dogs: effects on skeletal, physical, and behavioral development.
https://www.ncbi.nlm.nih.gov/pubmed/2045340
From 1991 and n is very small. Growth plates closure delayed in neutered dogs. Early neutered males found to be more active and excitable than intact males.

Long-term outcome of gonadectomy performed at an early age or traditional age in dogs.
https://www.ncbi.nlm.nih.gov/pubmed/11195826
4 year study, found no differences in small n of dogs physically or behaviorally between early and late neuter. Early neuters were more prone to infectious diseases however.

Endogenous gonadal hormone exposure and bone sarcoma risk.
https://www.ncbi.nlm.nih.gov/pubmed/12433723
http://cebp.aacrjournals.org/content/11/11/1434.long
Big n (71k), 2002 study. Neutered animals way more likely to develop bone sarcoma.

Long-term risks and benefits of early-age gonadectomy in dogs.
https://www.ncbi.nlm.nih.gov/pubmed/14765797
2004, n= 1842. Female dogs shouldn’t be spayed until after 3 months due to urinary incontinence. Early neutered had increased hip dysplasia, noise phobias, sexual behaviors. Claimed neutered animals had decreased obesity, separation anxiety, escape behaviors, and less fear related inappropriate elimination.

Canine ovariohysterectomy and orchiectomy increases the prevalence of ACL injury.
https://www.ncbi.nlm.nih.gov/pubmed/15577502
2004, n=3218. Neutered animals had higher incidence of anterior cruciate ligament rupture compared to intact animals.

Determining the optimal age for gonadectomy of dogs and cats.
https://www.ncbi.nlm.nih.gov/pubmed/18052800
http://avmajournals.avma.org/…/10.2460/javma.231.11.1665
2007 review that talks about cancers, cats, dogs, incontinence, and desirable behaviors that pet owners want.

Differences in the proportion of collagen and muscle in the canine lower urinary tract with regard to gonadal status and gender.
https://www.ncbi.nlm.nih.gov/pubmed/18703223
Neutering increases collagen and decreases muscle proportions found in neutered animals lower urinary tract. Could explain why spayed females experience incontinence.

Effects of gonadectomy on prolactin and LH secretion and the pituitary-thyroid axis in male dogs.
https://www.ncbi.nlm.nih.gov/pubmed/18996577
I didn’t understand this one well, but it seems like if there is a dopamine-2 receptor agonist treatment used in a neutered male long term they may be at higher risk of hypothyroid issues?

Effect of the gonadal status and the gender on glycosaminoglycans profile in the lower urinary tract of dogs.
https://www.ncbi.nlm.nih.gov/pubmed/21777968
In neutered dogs glycosaminoglycans (GAG) profiles were altered in bladder tissues and the lower urinary tract. Neutered females had more consistent changes in GAG composition and concentrations than neutered males.

Evaluation of the risk and age of onset of cancer and behavioral disorders in gonadectomized Vizslas.
https://www.ncbi.nlm.nih.gov/pubmed/24432963
2014, n=2505. Neutering increased risk of mast cell cancer, lymphoma, other cancers, fear of storms. Dogs neutered at less than 6 months of age had increased risk of developing behavioral disorder. Earlier neutering also meant earlier onset and diagnosis of cancers and behavioral disorders.

Effect of age at gonadectomy on the probability of dogs becoming overweight.
https://www.ncbi.nlm.nih.gov/pubmed/23822081
n=1930. Neutered animals at greater risk of being overweight.

A literature review on the welfare implications of gonadectomy of dogs.
https://www.ncbi.nlm.nih.gov/pubmed/28467742
http://avmajournals.avma.org/…/10.2460/javma.250.10.1155
Comprehensive (free) review that talks about cancer, behaviors, and orthopedic diseases. It also talks about lifespan studies and population management.

Survey of veterinary practice policies and opinions on neutering dogs.
https://www.ncbi.nlm.nih.gov/pubmed/20382933
Vets in Great Britain can’t agree on when to neuter dogs.

Complications of ovariohysterectomy and orchiectomy in companion animals.
https://www.ncbi.nlm.nih.gov/pubmed/21889699
Complications associated with neutering.

Pyometra and its complications.
https://www.ncbi.nlm.nih.gov/pubmed/2520100
Complications from not neutering females.

Canine pyometra: What is new?
https://www.ncbi.nlm.nih.gov/pubmed/27807901
More pyometra warnings.

Energy requirements of adult dogs: a meta-analysis.
https://www.ncbi.nlm.nih.gov/pubmed/25313818
Neutered animals have lower caloric requirements than intact animals.

Markers of Oxidative Stress in Dogs with Myxomatous Mitral Valve Disease are Influenced by Sex, Neuter Status, and Serum Cholesterol Concentration.
https://www.ncbi.nlm.nih.gov/pubmed/28132441
One marker of oxidative stress was found at higher levels in neutered dogs with myxomatous mitral valve disease. The other investigated markers were not influenced by neuter status.