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My Parsons Jack Russell terrier is five and as yet has not been spayed. The vets have told me that this is something I should do sooner rather than later (I've decided not to breed from her which I was originally going to do). The vet has said it leaves them open to a lot more nasty infections and diseases if she's not spay. I've also been assured it won't change her temperament or behaviour but I'm very unsure. Any advice would be really appreciated. Thanks.