Adding new pullet to a flock and a injured chicken

I've had 4 chickens for a little less than a year now. Recently one was attacked by a dog
We are not sure she is going to live. She is avoiding her food and water. And for some reason seems blind in one eye.
No visible injuries but she is limping. She has improved a little over the last 3 days and can walk around now. But yeah, I haven't seen her drink or eat anything.
Any advice on that weird blindness thing would be good. Has any one had that before?
We had a accidental 5th chicken for a short time when they were pullets. And that one was a different breed and from a different flock and was rejected by the original 4.
She got the same blindness thing and we had to put her out of her missery after hand feeding for a week.
She just got more and more blind until you had to dip her beak to get her to find the water you were holding right in front of her.
Really weird and I can't find anything online about chickens loosing their vision due to stress.

My second question is about adding a new pullet to the flock if my chicken does die.
I don't want a repeat of the first accidental bird. I've read some stuff about keeping them separate but so they can see each other for a few days.
And I will try and get the same breed so that they look similar to the older birds. I've read that these birds (brown shavers) tend to be a bit "racist", ha! (chicken breedist?).

But other than that I was just going to let the pullet loose after a few days and hope for the best.

Looking forward to all your advice!

I have no knowledge about chicken blindness, but with a rapid internet search I don't see any obvious links to major disease, but I do see a link to nutritional deficiency.  This can also cause lethargy and lameness in birds, though I'm not suggesting her lameness wasn't caused by the dog.

Knowing how she was injured by the dog would help to better her odds.  I had a chicken get chomped by a dog once; it grabbed her around the back and bit into her ribs, under the wings.  Her back was all messed up and everything was bruised and green.  I didn't know beans about herbal healing or alternative medicine at the time, but I used tea tree oil on her wounds every day, kept her in a carrier, and she healed and lived a few more years before dying of internal laying.  I'm not saying to use tea tree oil.  I'm just saying that's what I did in that case, but I'm also saying I didn't actually know what I was doing, it just happened to work in that case

So can you identify her injuries?  Do you have photos?  Is she bruised or punctured?  If there is a nutritional issue going on that would complicate her healing.  Maybe a good starting point would be to get some vitamins down her.  One of the articles I glanced at said blindness can be caused by Taurine deficiency.  I don't know how true that is but it may be worth reading up on and verifying.

As far as adding a bird, every flock is unique in dynamic.  I've known people who keep hens that will KILL any new bird they try to introduce, no matter how much controlled introduction they tried.  (imo, that hen should be culled, not worth the headache, but not my flock!).  My first chicken flock grew a few times in bursts of 2-4.  At one point I had 6 hens who had integrated flawlessly with one another and had lived together for a year, and out of nowhere they were all bullying the smallest hen so badly she was reduced to hiding in a tree.  Nothing I could do would stop them.  I tried adding 3 more hens and it 'kinda helped' but it was still out of balance.  I finally added my first rooster, for 10 birds total, and the hen-hen aggression stopped in its tracks.  Fastforward many years and thousands of birds later, I've never had trouble since, but I've also never been rooster-less since, because I breed the birds.  I'm not saying a rooster is the ideal solution, nor the only solution, nor that it would work for everyone, but that helped my situation.  
Then take my neighbors; they have their first flock of 4.  They tried to add a grown hen and their girls were out for blood on this new hen.  So they gave the hen to me and kept their 4.  Then they raise a bunch of male meat birds in an isolated pen this spring, and one ends up being a hen, so they experimentally throw her in with the 4 ladies.  Right as rain.  The girls don't care, don't bully her at all.  So then they added a rooster to the mix and hey, everyone's chill with him, too!  The 4 girls liked these 2 new comers I guess!

Birds are silly creatures.  The best you can do is try it out, be cautious, take whatever precautions you feel you need to, and watch their interactions.  Pecking order scraps are normal, but my rule of thumb is that there is no need to draw blood.  If someone's out for blood it's a problem.  If they're just kicking and wrestling, it's okay.  And integration can go on for several days, too!  Keeping a close eye on the flock dynamics is the best way to keep everyone safe.  But with any luck, they'll take the new girl with ease!  

Also; while, yes, keeping them together but separated with a fence is a good way for them to get used to one another- when you actually go to put her physically in with the other birds though, do it at night.  Set her up on the roost and let her wake up with the flock.  This is usually way better for the dynamics than tossing a new bird in during the day

Notwithstanding the likelihood of disease in the flock, the blindness issue could be caused by severe stress. Chickens are prone to a number of complications and a lot of them stem from stress disorders: environmental stresses like too hot/cold/windy, etc; and ‘neglect stresses’ like lack of nutrition, clean water, protection from predators, flock changes, etc.

Happy chooks produce lots of eggs.

I don’t agree that birds are silly creatures, each species has its foibles. Some breeds are indeed smarted than others. A study was conducted by the Brits that indicated the average chicken is as smart as the average dog, just they think and do things in a different pattern and manner.

[Surprising how often people mention dog attack. I’m not a dog lover, so would sooner dispatch a dog to God than have my poultry injured or killed by them – poultry provide more benefits anyway.]

Adding new birds to a flock is relatively easy:

Firstly, quarantining for a week or so is best to ensure disease prevention – observation of the bird/s, introduction to new/altered diet and conditions, checking faeces for worms, etc.

Then, place them in a cage beside the existing flock so they can interact and become familiar for a week.

After that they can be incorporated into the main flock – there will always be some fighting as they reform the pecking order, but that should only last a couple of weeks at the most.

One other thing to perhaps consider is perching space for the additional birds - the pecking order on the perch is important to them, so adequate space will be needed to avoid fighting.

Thanks Guys! That's really helpful advice.
I wonder if it could be a deficiency? Maybe one that is subclinical and symptoms only become apparent after a stressful experience?
All my chickens eat layer pellets, soaked wheat, and as many greens as I have time to bring them from my vege garden.
They also have access to my compost bin so they have all the food scraps etc. The food scraps are probably the only food source that varies by location (and thus soil profile).
So is the best bet for ensuring they get enough minerals.
They have eaten fish though! Whenever our landlord gives us an extra snapper. And that should have all the minerals in the sea. Hmmm, interesting!
I could try collecting fresh seaweed for them (if I find the time!) and see if they eat some.

I work full time so spending time on my chooks is my main limitation at the moment. Also, I rent in the suburbs which means rotating their pasture and getting a rooster are sadly out.
For now! One day I will have enough money to get a place!

The injured chook doesn't have any visible injuries. But I haven't really checked her over. I'm too worried about hurting her. I was at work when the dog got in and another tenant on the property got the dog off her.
This is day 3 after the attack (that sounds like the start of a bad sci-fi), and she is walking around the run now!
She is still not eating or drinking very well. She tries to eat perpetual spinach out of my hand if I offer it. But she is very feeble and often misses the leaf or drops the piece she pecks off.
She seems unable to peck at grain. And I have only observed her next to the water, not actually drinking it. I also spotted her having a really good stretch of one leg today, which is a good sign!

One of her eyes is a little squinty, and she holds her head on a weird angle a lot of the time. I have a feeling the dog got her by the head or neck and gave her a shake.
But a lot of improvement! Day one she just stood with her tail down and her feathers fluffed all day. The only time she moved was to have a gulp of water the I dipped her beak in.
And yesterday seemed worse because she actually tried to escape if I put food or water in front of her face. Like she would turn around and put her face in the corner.
Which in any language says fcuk off and let me die in my opinion, so I was pretty sure we were going to lose her.

But yes! walking around and eating greens, no matter how little is an improvement, and if she is improving there is hope! If she recovers I won't get another chook.
I'll keep you all posted

When I had to integrate a new chicken into the flock, what worked was to keep her in a cat carrier for 3 days, with her own food and water, inside the coop with the others. It was in the middle of winter, so that made it easier since this one refused to go out in the snow anyways. After 3 days, I let them out together and watched closely. There was some squabbling, but nothing violent. Now she's a happy member of the flock.

The cat carrier also works to isolate an injured chicken without them feeling lonely. I've noticed that when they're separated by too much, the one that's alone will start stressing to the point where she'll look like she's having an anxiety attack.

Also, some electrolytes might help the injured one recover. If she won't drink, you can dip greens and such in the solution. Or, make a small batch of oatmeal and add the electrolytes to that. They'll usually eat cooked oatmeal.