Penicillin and quarantine questions

I swear I'm not suppose to ride my mare. 6 years of thing after thing. Anyways, onto the latest problem:

Last Saturday a friend dropped her one mare and her yearling off at my dad's place. My dad boards out a few horses for friends and my friend's horses had been a few days without feed (she wasn't notified, she went out after a few long days of work to find out he wasn't feeding them anymore) so she brought them out. These two were pastured with a mare and a gelding that have been hauled into the town's indoor every Sunday. All horses on this property had their yearly vaccines last spring and the property is miles away from the indoor arena. Its just a public riding area that does have some boarding.

I was out at my dad's today and I noticed that her yearling was a little snotty. I just assumed it was because she had her head buried in her hay when I walked up. She was alert and nickering and following me around. She went ahead and wiped her nose on my mare's face. Everything else seemed all fine and dandy.

When I got back home I sent a message to my friend teasing her that she owes my mare a face wash and then she got all concerned, asking if the yearling or the other mare had a cough or anything else. Turns out a pretty nasty flu is going around the indoor arena right now and the one mare that was pastured with the other two came down with it yesterday. The other horse just has a very slight cough. So that is 4 days after the mare and yearling, who never were off the property to go to the infected arena, came into contact with my mare.

Back in the spring my friend was suppose to give my mare her yearly vaccines along with the other barn full when we boarded together. Now she doesn't remember if she actually got around to my mare and I don't remember confirming. Stupid I know, but its done and there is nothing I can do about it now other than make sure I see the needle go in and write it down on my calendar from now on.

She has her horses that were at the indoor on a run of penicillin now and will probably start her other two on penicillin if tomorrow when my dad checks on them there is any snot or cough.

Should I put my mare on antibiotics even without symptoms?
And what other good choices are there that are not penicillin?
Last time she had penicillin injections she broke out in hives. I'd also prefer something oral that can be mixed in feed because I can't be out there everyday and dad really doesn't want to give my horse shots. If only she was a cow.

I was suppose to be moving her to a new barn on the 5th. When I am out there for my lesson on Monday(barn's horse) I am going to tell the barn manager everything, but if my mare stays symptom free until the 5th, what are the odds she is carrying? I've been waiting for this spot to open up for awhile and the BM did me a big favor by bumping me up to the top of the waiting list, so I'm quit ticked I might loose it now.

I don't know much about colds and other equine sicknesses, so I have so many questions in my head. Like on average how many days does a horse exposed to a sick horse develop symptoms if it is going to get sick?
How many days after the symptoms clear up would it be considered safe to be exposed to other horses?
Is it to late to quarantine the possible sick yearling and mare? They are in with 3 other horses and my mare is just across the fence from them.
Is there even anything in a typical yearly vaccine that would have protected my mare?
And what I feel sad not knowing after 14 years of learning everything I can about horses, whats the difference between a horse flu and cold?

I'm calling the vet tomorrow to see what she has to say, but until then I still have so many questions.

Thank you to anyone who reads this and extra thanks to anyone who takes time to answer my one hundred and one questions.

Well if it is a Virus that is going around your barn, Penicillin will do nothing. If its a Bacterial infection...then penicillin is a good choice.

But you first need to find out from your vet exactly what type of infection is running through the herd. If its viral...not much can be done but to let it run its course, and give medication for the symptoms..i.e zev for a cough etc.

Its much like us...if you go to the doctor w a cold...they aren't going to give you antibiotics (or they shouldn't!)...but if you have a bacterial infection such as bronchitis or pneumonia then yes a form of penicillin usually will nip it in the butt

If she is breaking out in hives with Penicillin then you should consider getting some sulfa tablets from your vet. They are taken orally and can be used for up to about 14 days (Penicillin can be used long term).
I stock my vet kit with sulfas and then if I call the vet and he says "put him on antibiotics" I can just mix up a batch and start them.

Anyways, as far as actually treating whatever this is, it depends on what it is! I would at least call the vet. If it is flu or rhino then I would start on antibiotics. If it's a cold there really is not much you can do besides wait.
Take the horse's temp and vital signs (respiration/heart beat) and report that to the vet.

Good luck!

Good news is it never did reach my dad's farm.
It'd be 10 days now since the yearling was dropped off and not a single creature at dad's farm has any snots, sniffles, coughs or fevers.

The yearling must have just had hay up her nose like I originally thought, and the mare that she may have gotten sick from cleared up in a couple days. I guess she is really bad for licking everything she is tied to, so it's not surprising she would pick up anything possible some horse could have brought in. But when you actually look at the dates, odds were slim. The mare was at the indoor Jan 9, the yearling was moved out to dad's the 22nd, the mare was next at the indoor the 23rd and then got sick on the 26. That's just to great of time span for the mare to have picked something up the 9 and then not show symptoms until the 22.

The ones at the arena sounds like they were just quarantined and let everything run its course. My friend just dosed penicillin as a precautionary I guess.

Thanks you two!
And I'll remember about the sulfa tablets.

Another question, is which is more common? Viral or bacterially?