Our three dogs all have a rash and bleeding sores on their backs and tail, sometimes on their belly, it looks like poison oak or one of those poison plants, can dogs get poison oak ?

I see conflicting answers elsewhere online, but I tend to believe the sites that say they can, but it's uncommon.
Flea infestation can result in hair loss and sores because the dogs can only reach their rumps and tails and legs to chew there.
Are you using flea control such as drops?

I see conflicting answers elsewhere online, but I tend to believe the sites that say they can, but it's uncommon.
Flea infestation can result in hair loss and sores because the dogs can only reach their rumps and tails and legs to chew there.
Are you using flea control such as drops?

Yes, but the dogs do stay outside.

Where do you live?
I'm in New England. The wet spring has created monster mosquitoes and ticks. No fleas on my pets but they get drops. I would examine them very carefully.
Last year my dog was bare and sore around her rump from fleas because I hadn't started the drops 3 months earlier! I was so mad at the company (Frontline) that I won't use them anymore.

Where do you live?
I'm in New England. The wet spring has created monster mosquitoes and ticks. No fleas on my pets but they get drops. I would examine them very carefully.
Last year my dog was bare and sore around her rump from fleas because I hadn't started the drops 3 months earlier! I was so mad at the company (Frontline) that I won't use them anymore.

We live in Arkansas, we do have fleas and ticks, but we moved out in the country, We have a lot of poison ivy and poison oak, can dogs get poison ivy ?

We live in Arkansas, we do have fleas and ticks, but we moved out in the country, We have a lot of poison ivy and poison oak, can dogs get poison ivy ?
Yes, and here is one site of many that explains more -- Dog Poison in Dogs | Information on Canine Poison Ivy (http://www.petwave.com/Dogs/Health/Poison-Ivy.aspx)

Do you have so many dogs that they can't sleep inside at night? IF they are in a clean kennel at night then why are they in distress?

Dogs can 'get' anything we do.

Do they get regular baths, do they get regular vaccinations and vet checks?

Sorry. And don't tell me your dogs are well cared for, it doesn't appear so. Vet Check is my advise. I always have the money for my pets.