Welcome to the board, mahmood! We'd love to see pics of your pup if you have some to share! Donut sounds adorable!!
We've had a number (over a dozen individuals and 3 breeds) of dogs, neutered after varying lengths of time (from 9 mos to 2 yrs) and we've never had any of them get aggressive from it. (Lili was just spayed last Thurs at the age of 2 after her second heat, so I guess the jury is still out on her.) If anything, they end up a little more laid back, but mostly they stay about like they were before the procedure. If there
were changes, they were minimal.
Our dogs were bigger--labs, springers, and English setters, so I have no experience with smaller breeds, but my feeling is that if your dog is well-adjusted and happy now, she'll continue that way after her spay.
The only negative effect we've noticed in our neutered fems is spay incontinence. Of the 6 fems (not including Lili, since we won't know for a few months after the hormones leach from her system), 5 of them needed treatment with Proin for minor leakage. Interestingly, they responded to well under the recommended dosage, and as long as they got their daily meds, it wasn't a problem. We were running a bit above the average--I've seen figures that say about 30% of fems develop the problem after spay.
