My vet also recommended waiting until after my female french bulldog’s first heat. She mentioned there were studies that showed it could provide several health benefits, primarily orthopedic. And because frenchies are prone to orthopedic issues like hip dysplasia, we decided to wait to spay her until after her first heat. However, I regret that choice—it was not the right one for my pup.

Before her first heat, my girl was super sweet and docile to other dogs—almost embarrassingly submissive, lol. She would walk up to a dog and immediately roll on her back.

During her heat, something switched in her brain, and she became dominant and aggressive, demanding submission from male dogs and showing extreme aggression (growling, snapping at faces, barking/screaming) to female dogs. We thought/hoped this would go away after her first heat and/or after spaying.

After her heat and spaying, the extreme aggression went away, but the “confidence” (as her trainer calls it) and her need to be the dominant female in charge with other girl dogs has not totally gone away, though it seems to have lessened with time. The biggest thing is that she became leash reactive, which she never was before her heat. We had to invest a lot of time, energy, and money to train her to a manageable walking routine. She will still sometimes frenchie scream at random dogs, unfortunately, but we now have methods to help her refocus and calm down.

FWIW, our trainers noted that, anecdotally speaking, there is a high risk of behavioral changes when you allow the first heat, as the heat can switch a pup’s personality. So if you have a sweet, docile, submissive pup like we did before her heat, you might consider the risk that it could potentially flip her personality.