Why is my dog so nervous?

[Tinytigertail]

We rescued our dog a couple of months before lockdown. Over the last year or so, her behavior has really changed. She can be quite snappy and growly with other dogs, she's clingy and always underfoot and she has started to bark really loudly if someone comes to the door or even just walks past. She's started to go crazy when the postman knocks, to the point where our mail is getting damaged with l tooth marks. There is usually someone at home with her for most of the day and she is walked at least once a day. We tried one of those plug in things to soothe her and it did nothing. Any suggestions to calm her down a bit? She seems to be getting worse.

Have you taken her to the vets?

What breed is she? And how old?

Depending on breed and age it could be illness and/or injury. Or it could be lack of exercise (a known reason for why dog behaviour can get really bad) or mental stimulation if she's a particular breed...

She's a mixed breed, looks like she has some Jack Russell and maybe some Staffy in the.mix, but can't be sure. We don't know how old she is, as she was found, unchipped and wandering the streets. Our vet estimates that she is around 6 years old. I haven't taken her to the vet yet, as these changes have sort of crept up on us. Perhaps she does lack some mental stimulation, she's quite a clever little thing.

Ah! Staffies and Jacks are really intelligent, so it could well be that. Maybe add some mental stimulation to her daily schedule and potentially another 15 minute walk? Both are high energy breeds (1-2 hours a day) so one walk a day might not be cutting it and sometimes it's easy not to realise you've cut back on walks (a few minutes here or there suddenly adds up) and that, actually, your dog really needs more.

I'd also check in with a vet though if she's not shown any improvement in a week. It could well be under-stimulation (my dogs have always gone mental if they don't get enough 'mental exercise') but it could also be pain (particularly if the barking is more aggressive than it is 'alerting') - so it's best to be 100% sure and cover all bases.

I hope that's vaguely helpful :)

Please get her vet checked, and see what they say. My guess would be she's under stimulated and needs another walk or some brain games/ fun training. Could you take her to something she would enjoy, maybe give agility a go, or man trailing (I have no idea not knowing her whether she would be suitable or enjoy this sort of thing).
I buy marrowbones for a rainy day for my (large breed) dog, then stuff them with mashed frozen veg/wet dog food and freeze - I always have about 6 in the go in the freezer. The new marrowbones keep him chewing for about an hour. Then I take them away and wash them and stuff them. Warning: they are very fattening but clean teeth extremely well.
Nina Ottosson does some fab toys and puzzles for dogs too, or hide her kibble (if she is fed kibble) in old toilet roll or kitchen role tubes and squish the ends in then hide again in old Amazon boxes, he has to use his nose. Sniffing and hunting all drains the brain. I also feed my dog half his morning kibble scattered in the garden/grass and he has to find it-this gives me time to get up in peace and get ready. He loves this game. Always is a we and a poo on this time, too.
I take the rest of her kibble out with me each morning and use it as training treats. We train every single day - even just a simple 'wait' once or twice, or recall.
I also play 'find it' with him and hide the kibble in various places on our walks. I vary the walks so he doesn't get bored. We have fun. Your dog sounds lovely - have a Google - there are so many games you can play.

Thank you both for some excellent advice. As of tomorrow, we are back to two walks a day. We will also try the trick of giving half her kibble in more interesting ways. I'll also look for some toys that might keep her occupied. If there is no improvement in a week, I'll book her in for a check up at our vets. I'll report back!

I think she needs to see the vet regardless - you should always get behavioural changes checked out sooner rather than later.