
Not all cavaliers get a curly coat as they get older my two older boys have exactly the same coats they had when younger
Bitches do tend to keep their coats more if spayed, but nothing you can't cope with unless she already has a very heavy coat
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They do tend to go curly if you have them clippered tho'(my friends a groomer & has had to sort out lots of clippered Cavaliers, she scissors them if the owners insist they are trimmed, but she doesn't like doing it)
Depends very much on how much coat your girl has already. I don't "do" female dogs(the bitch GSD I have is rescued & is spayed-part of the rescue rules).
You will have to keep an eye on her weight if she's a piggy(my cavaliers aren't for some reason), but if want to have her spayed go ahead as long as you & your vet are happy & her heart is ok