Hi OP. Your hens should settle back after a while. Poultry Spice is also a good thing to include with their food or with a warm mash if they are going through a moult or time of stress, or introducing new hens. I'm sure they will recover from the trauma of the dogs.
What I was going to say though was about introducing the new hens you get. If you haven't ever done it before you need to be really careful. If you've been reading up on it then you will be getting an idea that it won't be necessarily straight forward.
I've had hens for nearly 8 years and in that time I built up from 2 old hens my neighbour gave me (which didn't lay regularly) to up to 16. Although I've currently only got 13 girls. I've introduced new hens to the flock every couple of years to ensure I've got good egg supply, so I've got very mixed ages, and have gone through introduction quite a few times.
Some people swear on putting new hens in the coop after dark so that they wake up with the new hens in with the old birds. I've never found that to help. I was told when I was new to hen keeping to introduce half of the existing flock (which didn't help me, I just had 2 traumatised and terrified new hens). In your case that would be 1 hen which is definitely not a good idea. You need it to be at least 2 new ones, and don't think 'Oh its not working, maybe I'll get a few extras to see if that helps.' It won't. I did that and went from 2 terrified new hens to 6 living in terror of my neighbour's donated hens who totally dominated them. It was a very long summer and at the time I had all eight free ranging in my garden with plenty of space to get away from each other. The original 2 were established pair and terrorised the others!
The only successful and stress-free way I've been able to do Introduction is to have 2 separate hen houses and you need either 2 enclosures or divide a large enclosure in half. Keep the birds separate, but put all their food and water next to the boundary so that they come and eat and drink next to each other over a week. Likewise any corn feed each flock at the same time on either side of the boundary. Try hanging any goodies like cabbages on the boundary so they get used to sharing up close. Then when you've done that for a number of days, introduce 1 of your hens (the least dominant the better) in with the new girls under supervision. There will be some argy bargy but if you are there you can stop it if it gets really nasty. Also if there's serious ongoing pecking try Anti pecking spray and Battles poultry coal tar on affected areas especially if any bad wounds.
Even if I'm introducing 4 or 6 new hens I only put one of the established flock in. It might be for very limited time and it might be you have to do this a number of times over a few days before you leave the older bird in there to spend the night. I then tend to add another one of the flock in and let that settle before adding a number of the others in gradually. Last September I was given 4 new hens by someone who couldn't cope with them and did the usual process. However I also had a temporary Omlet fence around the lawn which they hadn't had access to for a while and opened the gates to the 2 enclosures (you might not be able to do that with the Bird Flu restrictions) and they had limited daily access to that before being given corn to get them back in enclosures. The lawn area meant there was alot of space to avoid each other and the existing flock was distracted by grass and digging in flowerbeds. Within a couple of weeks of doing that they were mainly all in the one enclosure at night and then very soon in the one coop.
Don't know if that helps OP, but hope it goes ok.