This is an issue of WHEN is the BEST time, not when is the right time. You can take your female in to spay her tomorrow if you'd like. This issue of spaying a Swiss Mountain Dog bitch PRIOR to their first heat cycle is an issue of the EXTREMLY HIGH INCIDENCE of urinary incontinece in THIS breed for all those owners and veterinarians across the country who elected to spay a Swissy female prior to their first heat cycle. No one has done any formal research on this, and someone should.....we're in the midst of data and documentation on our bigger issues......bloat, epilepsy, OCD, etc....Not only do the frequent episodes of vaginitis and UTI's in Swissy females reduce (and if not almost disappear after the onset of the first heat cycle), the incidence of incontinence throughout life also reduces. I don't want to come across as being rude, but I would just like you and your vet to also seek the opinions of the following doctors that have a lot of experience with THIS breed (Dr. Greg Svoboda, Dr. Jackson, and Drs. Beamer or Dr. Byrd) you run the risk of Aggie developing the urinary incontinence. If after consulting with these doctors they say, "what the hell, spay the dog now," then so much for the anecdotal evidence that nobody has mustered the energy or time to formalize in a documented research study yet (it will happen, it will be someone's thesis or graduate research one day).
I'm emotionally driven and feel so strongly about this after my own personal experiences with Julee and her progeny, that I only needed to be burned once to understand what others have always advised me for years, I didn't heed myself. Do what you may, I'll be here to support you regardless of the outcome, but I feel better knowing that I did the very best I could to convince you and ALL my female companion puppies I place (which is better than 90% of the pups I produce) to STRONGLY ENCOURAGE owners to push the "envelope" to the first heat cycle. Also, know that you have your own female who has developed a UTI, a full sibling that has developed a UTI (Gem), a full sibling that possibly is having some difficulty concentrating urine (Luna) and a half-sibling who is incontinent after a spay at 12 months and was completely continent for the 12 months prior to the spay........all as cards stacked against you genetically. My Julee, who developed her incontinence after 3 litters and being spay at 5 1/2 months, more than likely experienced what they call estrogen-responsive urinary incontinence (but this can happen to bitches spay at any age and is usually treated with either diethylstilbestrol, DES, or phenylpropanolamine, Proin, which act to improve the closure of sphincters in the urinary tract). Estrogen-responsive incontinence's exact pathogenisis is unknown, but most bitches clinically present for "leaking" urine when relaxed and owners notice it's onset when they find urine spotting wherever the dog typically sleeps. This type of incontinence is more typical in bigger dogs, weighing more than 44 pounds, and in dogs spay at an early age. Julee's grandaughter, Mulligan, was spay at 7 months when she had her OCD lesion surgery and she was incontinent from her recovery on (prior to her surgery there was no incontinence). Lola, half-aunt to your Aggie, developed incontinence at 6 1/2 years of age, after having three litters and was never incontinent prior to that. Lola's full sister, Gretchen, was spay at 7 months and was incontinent from that day forward, they just turned 7. All the other littermates have reported no incontinence. Lola has produced two daughters, Mattie Rose in her first litter, and Nelli in her third litter, that both have estrogen-responsive urinary incontinence. Lola produced 24 puppies total in her lifetime. There's nothing more I can really say on this issue except that I've done the best I can to be thorough and provide every ounce of information I have against spaying prior to a first heat cycle. I suppose I always have the option to revise my contract to reflect my opinions on this issue. Thank God for the males, RIGHT?!? Don't worry, they come with their own set of baggage.
Talk to other breeders, other Swissy owners, the vets I know that have the MOST experience in this 100 mile radius with THIS breed, and whoever else you can before she goes under anesthesia......I'm totally confident that whatever the result, you'll handle.