
One of my girls gets very hormonal when pregnant, normally a happy girl but as soon as she's in season or pregnant she turns really grumpy! She's never snapped, but just growls and barks which makes it a bit difficult when people come to see her to see what her pups will turn out like........lol. She even growls at her mum when she gets close, she was the same once the pups were born too, but soon settled down!
I'm sure it's just her hormones, as long as she seens ok in herself and you've no worries about her then she's probably feeling fat and fed up!
If you are worried then take her to the vet and get her checked over!