Here's why visual clues aren't reliable:
* Spay surgery involves removing the ovaries and uterus, but the external appearance of the vulva remains largely the same.
* Dogs can have other medical conditions that might affect their appearance, such as infections or tumors.
* Some owners choose not to remove the external genitalia during spaying, leaving the vulva intact.
While it's impossible to tell for sure, there are a few indirect indicators that might suggest a dog is spayed:
* Lack of heat cycles: A spayed dog will not go into heat (estrus) as an intact female dog would.
* Behavioral changes: Spayed dogs often become calmer and less likely to exhibit behaviors associated with heat cycles, such as restlessness, vocalizing, and attracting males.
* Microchip information: Some microchips contain information about a dog's spaying status.
* Identification tags: Some owners put tags on their dogs that say "spayed."
Remember, it's always best to respect a dog's privacy and ask the owner if you have any questions about their health or medical history.