Spay and Neuter: When and If ever?

[pstinard]

I was able to access the following online article about the effect of spaying and neutering on the incidence of ACL injury:

Canine Ovariohysterectomy and Orchiectomy Increases the Prev... : Clinical Orthopaedics and Related Research

Here's a table from the article (sorry for the formatting):

TABLE 1. Prevalence of ACL Injuries
Gender, Number in Sample, Number of ACL Injuries, Prevalence (%)

Female
Sexually intact, 742, 18, 2.43
Spayed, 1067, 55, 5.15
Total, 1809, 73, 4.04

Male
Sexually intact, 861, 18, 2.09
Neutered, 548, 21, 3.83
Total, 1409, 39, 2.77

Male and female
Sexually intact, 1603, 36, 2.25
Spayed or neutered, 1615, 76, 4.71
Total, 3218, 112, 3.48

It looks like the rate of ACL injury is approximately doubled in neutered males and females. Note, however, that the rate of injury is still low, and that one cannot prove that neutering was the cause of ACL injury in any particular animal. Also, these are the rates in dogs that were seen by an orthopedic specialist, so they are prescreened for having some sort of orthopedic issue.

I will look further into this article and post any additional findings about the rates in small dogs, if I can find any.

[Maximo]

Originally Posted by megansmomma

That was my point if posting the entire article. When you read the article along with this chart it kind of discredits several of the highs as being human not spay/neuter related. It was repeatedly numerous times that these states were in large or giant breed dogs as well and that there are no studies for small breed animals.

Yes, the article does discuss the human factor.

Gail did indicate that these studies were large breed dogs and that she would like to see them done for small breeds, Yorkies in particular.

[pstinard]

Originally Posted by pstinard

I was able to access the following online article about the effect of spaying and neutering on the incidence of ACL injury:

Canine Ovariohysterectomy and Orchiectomy Increases the Prev... : Clinical Orthopaedics and Related Research

Here's a table from the article (sorry for the formatting):

TABLE 1. Prevalence of ACL Injuries
Gender, Number in Sample, Number of ACL Injuries, Prevalence (%)

Female
Sexually intact, 742, 18, 2.43
Spayed, 1067, 55, 5.15
Total, 1809, 73, 4.04

Male
Sexually intact, 861, 18, 2.09
Neutered, 548, 21, 3.83
Total, 1409, 39, 2.77

Male and female
Sexually intact, 1603, 36, 2.25
Spayed or neutered, 1615, 76, 4.71
Total, 3218, 112, 3.48

It looks like the rate of ACL injury is approximately doubled in neutered males and females. Note, however, that the rate of injury is still low, and that one cannot prove that neutering was the cause of ACL injury in any particular animal. Also, these are the rates in dogs that were seen by an orthopedic specialist, so they are prescreened for having some sort of orthopedic issue.

I will look further into this article and post any additional findings about the rates in small dogs, if I can find any.

Info from the article about size of dog:

"Furthermore, dog size contributed to the probability of ACL rupture. In particular, compared with large dogs, medium (OR 0.38; p 0.001) and small dogs (OR 0.38; p 0.001) were less likely to sustain ACL injuries."

So in conclusion, neutering does increase the rate of ACL injury in small dogs, but it's not as large an effect as it is in larger breed dogs.

[107barney]

Originally Posted by pstinard

Info from the article about size of dog:

"Furthermore, dog size contributed to the probability of ACL rupture. In particular, compared with large dogs, medium (OR 0.38; p 0.001) and small dogs (OR 0.38; p 0.001) were less likely to sustain ACL injuries."

So in conclusion, neutering does increase the rate of ACL injury in small dogs, but it's not as large an effect as it is in larger breed dogs.

This says nothing about time of neutering.

[Maximo]

Originally Posted by pstinard

I was able to access the following online article about the effect of spaying and neutering on the incidence of ACL injury:

Canine Ovariohysterectomy and Orchiectomy Increases the Prev... : Clinical Orthopaedics and Related Research

Here's a table from the article (sorry for the formatting):

TABLE 1. Prevalence of ACL Injuries
Gender, Number in Sample, Number of ACL Injuries, Prevalence (%)

Female
Sexually intact, 742, 18, 2.43
Spayed, 1067, 55, 5.15
Total, 1809, 73, 4.04

Male
Sexually intact, 861, 18, 2.09
Neutered, 548, 21, 3.83
Total, 1409, 39, 2.77

Male and female
Sexually intact, 1603, 36, 2.25
Spayed or neutered, 1615, 76, 4.71
Total, 3218, 112, 3.48

It looks like the rate of ACL injury is approximately doubled in neutered males and females. Note, however, that the rate of injury is still low, and that one cannot prove that neutering was the cause of ACL injury in any particular animal. Also, these are the rates in dogs that were seen by an orthopedic specialist, so they are prescreened for having some sort of orthopedic issue.

I will look further into this article and post any additional findings about the rates in small dogs, if I can find any.

Once again, what evidence is there that points to causation vs correlation? I think there are environmental/human factors that would be very difficult to measure, especially for small breeds.

[pstinard]

Originally Posted by 107barney

This says nothing about time of neutering.

You're right about that. The article is still a good read. I'll send you a copy.

[megansmomma]

Originally Posted by 107barney

This says nothing about time of neutering.

This is my issue with trying to link it together. The research is pretty broad and almost always done on large breed dogs. I think we also need to take into consideration the idea that when a Yorkie jumps off the couch it would be equivalent in high to a GSD jumping off the top of (picking a piece of furniture) the chest in my bedroom.

[pstinard]

Originally Posted by Maximo

Once again, what evidence is there that points to causation vs correlation? I think there are environmental/human factors that would be very difficult to measure, especially for small breeds.

The article addresses these issues in the conclusions section:

One potential source of bias in this study is that only dogs whose owners sought care for lameness were included. This potential source of bias is inherent in all retrospective studies of clinic records. Of particular concern is the possibility that some dogs in our region (e.g., strays or pets of negligent owners) never receive veterinary care of any kind, including for spaying, neutering, or treatment for lameness. If such animals were a large segment of the dog population in our region, it would tend to exaggerate the apparent prevalence of ACL injury in spayed and neutered animals in our study because a population of nonspayed, nonneutered, lame dogs was not represented. However, one also must consider that our region includes a substantial population of highly prized, nonspayed, nonneutered dogs specifically bred for show and for working, especially hunting. Owners of such animals typically seek veterinary care routinely, and especially for conditions that are highly symptomatic, such as ACL injury. Consequently, this population might be over- represented in our study, and thereby would tend to exaggerate the apparent prevalence of ACL injury in nonspayed, nonneutered animals, in opposition to the effects of the stray and neglected population. Regardless, both of these populations are likely to be small in comparison to the overall dog population in our region, and therefore unlikely to affect significantly the conclusions of this study.

Comparisons of mechanism of injury between the dog and human are difficult. The anatomy of the dog knee (stifle joint) is different from that of the human knee. The active range of motion of the dog stifle is 46°–142°,14 whereas that of the human knee is 0°–160°. Dogs have a four-legged gait, so the dynamics of running and cutting are different from humans. These differences suggest the mechanism of injury in dogs is not the same as in humans. Nevertheless, the mechanism of injury is likely to be similar, and most, or all, of the external biases affecting ACL injury introduced by human behavior are minimized in the dog.

The effect of ovariohysterectomy and orchiectomy on the dog is complex and results in various body changes in the animal far greater than an effect seen solely from the absence of one sex hormone. For example, bone density decreases secondary to the reduction of the influences of sex hormones on calcium deposition into the skeleton. Despite the effect on bone, none of the injured animals had a ligament-bone avulsion at the time of surgery. Whether ovariohysterectomy or orchiectomy affect weight gain is controversial, but one study showed no significant increase.21,22 Additionally, ovariohysterectomy or orchiectomy could affect the behavior of the dog.21,22 However, an ovariohysterectomized or orchiectomized dog most likely would become less aggressive, less active, or both, probably decreasing the risk for ACL injury.21,22 Although we cannot predict all of the effects that could result from canine ovariohysterectomies or orchiectomies, many of the effects are likely to decrease injury risk.

The effect of decreased sex hormones on the ACL of the dog is not known. However, alterations in sex hor- mones may affect the size, shape, or material properties of the ACL. Anterior cruciate ligament remodeling is affected by loads placed on the ligament (Wolff’s Law). The remodeling of many soft tissues, including the ACL,1,5,7,13,15,16 also is influenced by sex hormones. In humans, elevated levels of estrogen decrease collagen pro- duction of the ACL in tissue culture. Additionally, expres- sion of an ACL remodeling gene is increased, on average, in human females. Gender differences in ligament remod- eling presumably would affect the size, shape, or internal structure of the ACL, thereby affecting its ability to sustain loads without rupturing. Therefore, it is possible that by altering ligament remodeling, a decrease in sex hormones would affect the predisposition of the ACL to injury.

Ovariohysterectomy and orchiectomy increased the prevalence of ACL injuries across sizes and breeds of dogs. These findings have established an alternative model by which the effect of gonadal gender on ACL injury can be studied, and are consistent with the view that ACL injury in humans is, in part, related to gender differences in hormone production and presentation.

[pstinard]

Originally Posted by megansmomma

This is my issue with trying to link it together. The research is pretty broad and almost always done on large breed dogs. I think we also need to take into consideration the idea that when a Yorkie jumps off the couch it would be equivalent in high to a GSD jumping off the top of (picking a piece of furniture) the chest in my bedroom.

Nearly 50% of the dogs in this study were small breed:

"When dogs were controlled for size, 229 (7.12%) were large, 1053 (32.72%) were medium, 1509 (46.89%) were small, and 427 (13.27%) had an undetermined size."

[gemy]

Originally Posted by pstinard

I was able to access the following online article about the effect of spaying and neutering on the incidence of ACL injury:

Canine Ovariohysterectomy and Orchiectomy Increases the Prev... : Clinical Orthopaedics and Related Research

Here's a table from the article (sorry for the formatting):

TABLE 1. Prevalence of ACL Injuries
Gender, Number in Sample, Number of ACL Injuries, Prevalence (%)

Female
Sexually intact, 742, 18, 2.43
Spayed, 1067, 55, 5.15
Total, 1809, 73, 4.04

Male
Sexually intact, 861, 18, 2.09
Neutered, 548, 21, 3.83
Total, 1409, 39, 2.77

Male and female
Sexually intact, 1603, 36, 2.25
Spayed or neutered, 1615, 76, 4.71
Total, 3218, 112, 3.48

It looks like the rate of ACL injury is approximately doubled in neutered males and females. Note, however, that the rate of injury is still low, and that one cannot prove that neutering was the cause of ACL injury in any particular animal. Also, these are the rates in dogs that were seen by an orthopedic specialist, so they are prescreened for having some sort of orthopedic issue.

I will look further into this article and post any additional findings about the rates in small dogs, if I can find any.

Shoot looks like it is behind a pay firewall. Awh well. Thanks for posting Phil.

[ladyjane]

Let us all keep in mind that most of the time CCL injuries are due to luxating patellas which are considered to be genetic. Some of these examples and comparisons are misleading if you ask me.

The bottom line is that someone said that MOST owners should not have intact dogs and I could not agree more. The vast numbers of unwanted dogs in this county is beyond comprehension; and I think it is irresponsible for anyone who truly loves animals to advocate that ALL pet owners worry about altering their pets. Of course those are just my thoughts....and yes, I know people will spout their opinions just as I will spout mine.

[gemy]

Phil does the study look at or researched activity levels prior to injury, weight, other osteo presenting conditions, and or other medical conditions, did it look at breed type at all? Age of dog at injury? Subsequent other legs ACL problem?

[ladyjane]

Originally Posted by ladyjane

Let us all keep in mind that most of the time CCL injuries are due to luxating patellas which are considered to be genetic. Some of these examples and comparisons are misleading if you ask me.

The bottom line is that someone said that MOST owners should not have intact dogs and I could not agree more. The vast numbers of unwanted dogs in this county is beyond comprehension; and I think it is irresponsible for anyone who truly loves animals to advocate that ALL pet owners worry about altering their pets. Of course those are just my thoughts....and yes, I know people will spout their opinions just as I will spout mine.

EDITED TO ADD THIS

Let us all keep in mind that most of the time CCL injuries are due to luxating patellas which are considered to be genetic. Some of these examples and comparisons are misleading if you ask me.

The bottom line is that someone said that MOST owners should not have intact dogs and I could not agree more. The vast numbers of unwanted dogs in this county is beyond comprehension; and I think it is irresponsible for anyone who truly loves animals to advocate that ALL pet owners worry about altering their pets. Of course those are just my thoughts....and yes, I know people will spout their opinions just as I will spout mine.

Of interest to me is that every time someone tries to keep the numbers of homeless pets down, people who breed them go out of their way to stop it. The very people who profess to love them so much. Try to limit breeding and you hear all the fear mongering about how there won't be any more dogs. Since around 2006 (when I first became aware of this issue that is being discussed) , breeders have used this hormonal issue to try to stop the push for spay/neuter. Again, the same people who are providing irresponsible pet owners with more pets to abuse and discard, speak up to try to stop people from bringing more into the world. It disgusts me....it really does. The first time I became aware of this little "movement" was in 2005 or 2006 when someone gave me the link to that NAIA article. Note it is breeders doing this. In my opinion they are only protecting their cash cows.

[pstinard]

Originally Posted by gemy

Phil does the study look at or researched activity levels prior to injury, weight, other osteo presenting conditions, and or other medical conditions, did it look at breed type at all? Age of dog at injury? Subsequent other legs ACL problem?

Hi Gemy, if you private message me your email address, I'll email you a PDF copy of the article. But the short answer to your question is no. They divided dogs by breed size: large, medium, and small, but didn't look at individual breeds. Here is the first part of the Materials and Methods:

MATERIALS AND METHODS

The records of all dogs seen and evaluated during a 2-year period in a one-surgeon orthopaedic veterinary practice were reviewed retrospectively. Each dog was identified and was counted as one unit of observation regardless of the number of visits. No dogs were excluded from the general population in the clinic. Inclusion criteria for the ACL-injured group were a history of hind-limb lameness, a positive anterior drawer examination by the orthopaedic veterinarian, and an observed torn ACL at the time of surgery. Breed, gender, ovariohysterectomy status, and orchiectomy status were recorded for all dogs.

[pstinard]

Originally Posted by ladyjane

Let us all keep in mind that most of the time CCL injuries are due to luxating patellas which are considered to be genetic. Some of these examples and comparisons are misleading if you ask me.

The bottom line is that someone said that MOST owners should not have intact dogs and I could not agree more. The vast numbers of unwanted dogs in this county is beyond comprehension; and I think it is irresponsible for anyone who truly loves animals to advocate that ALL pet owners worry about altering their pets. Of course those are just my thoughts....and yes, I know people will spout their opinions just as I will spout mine.

I agree with everything you say here. That's why I wish there were a science forum on Yorkietalk where we could dispassionately discuss the science behind these articles without fear of someone taking a single sentence out of context and reaching the conclusion that because there are *some* bad health effects of neutering, they therefore should not have their dog neutered. I agree that overall, the benefits of neutering far outweigh the drawbacks for all dogs except for breeding stock and perhaps a few sporting dogs who have extremely conscientious owners.