Orthopedic Considerations

Bitches spayed at 7 weeks  had significantly delayed closure of growth plates as  compared to those spayed at 7 months, and those spayed at 7 months  had significantly delayed closure of growth plates as compared to those left intact.

In a study of 1444 Golden Retrievers, bitches and dogs spayed or neutered at less than a year of age  were significantly  taller than those spayed or neutered after a year of age.

In a study of 203 agility dogs,  the  tibia and radius and ulna were significantly  longer than the femur and humerus, respectively, in dogs that were spayed or neutered at or prior to 8 months   of age as compared to intact dogs.

Several studies have shown that spayed and neutered dogs have a significantly higher prevalence of  CCL  rupture  even when controlling for body size.

Dogs that were neutered at least  6 months prior to a diagnosis of hip dysplasia were 1.5 times more likely to develop hip dysplasia than
sexually intact dogs.

Spayed/neutered dogs had 3.1 times higher incidence of  patellar luxation.

Dogs that have been spayed or neutered  at or before puberty can often  be identified by their longer  limbs, lighter bone structure, narrower chests and narrower skulls than intact dogs of the same breed  This  differential growth frequently results in significant alterations in body proportions and particularly the lengths (and  therefore weights) of certain bones relative to others.

For example, if the femur has achieved its genetically  determined normal length at 8 months, prior to a dog being spayed or neutered, but the tibia ( which normally  stops growing at 12 to 14 months of age) continues to  elongate for several months after that point because of the  removal of the sex hormones, then  the relationship between the femur and tibia will be different than what was  genetically determined.

This may result in  an abnormal angle  at the stifle and a longer (and therefore heavier) tibia placing increased stress on the cranial cruciate ligament (of the knee or stifle joint).
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It is well known that  spayed and neutered dogs  are more likely to be overweight or obese than sexually intact dogs, and this can be a contributing factor to  orthopedic diseases.