Hello and welcome to Just Answer. I am a licensed veterinarian and would be happy to answer your questions.
The viruses that cause stomach flu in people do not pass on to dogs.
How long has this been going on with him?
Is there blood in his stool again this time?
ok, so my flu isn't affecting him.
he has just started drooling this morning - for perhaps 2-3 hrs which is when i heard him start to cough and make a yacking noise like he was trying to throw up. he was doing that for perhaps an hour or two on and off.
his diarrhea started late last night and yes, he had a tiny bit of blood in his stool. i have not given him human food, i'm careful to keep the garbage out of his reach and there is nothing in the yard that he could consume that would make him sick as i'm careful to keep all chemicals etc out of his reach. i had visitors in this weekend who may have given him human food without realizing that it reallly makes him sick - i still have to check with them but i know i've told them not to give him human food but they occassionally give their dogs human food so they may have forgotten and given him some. they brought both of their dogs with them who appeared fine although the one dog had been sick a week or two ago w/ some kind of ear hematoma and bleeding nose rash.
his stomach is not distended, he ate yesterday without a problem when i gave him the boiled chicken and rice. he wanted to go outside but was straining when going so i believe he still has diarrhea. he wants to eat and he doesn't seem lethargic and has not lost any coordination. besides the drooling/attempted vomiting and the diarrhea everything else appears fine.
Colitis can have many causes including intestinal parasites, dietary indiscretion, food allergies or intolerances, metabolic disturbances from internal organ malfunctions, viruses, toxins, cancer or even stress. It is possible that even if he did not receive any human food, just the stress and change in routine of having visitors this weekend set it off. The drooling and gagging are a sign of nausea. If it continues, your veterinarian will want to know the history of his signs and will need to perform a physical exam to help rule out the other causes mentioned. A stool sample analysis is a very important part of getting to the bottom of this as intestinal parasites are one of the most common causes.
Until you can get in contact with your vet, I would fast your dog to give his GI system a rest. Since he is an adult dog, a 12-24 hr fast will not hurt him and will let his gut calm down. Continue to offer small amounts of water at a time. When you do begin feeding him again, you will want to offer frequent, small meals of something very digestible for him as you have been. These would include items like boiled hamburger or chicken and rice or pasta. No sauces or gravies, but a little non greasy broth would be OK. If the stools improve, I would continue that for a few days and then slowly wean him back onto his normal food and feeding schedule. If he won't eat, or if the diarrhea of nausea signs continue, or he just can't seem to get comfortable, I would have him examined.
When they have been going on chronically, these GI disturbances can be frustrating to diagnose and treat and sometimes we don't even find the cause, but concentrate on controlling the symptoms so our pets are comfortable. In his case, since it appears to be an acute flare up, there is no reason to think that it won't resolve completely. Make sure to get in touch with your vet if he is not improving so they can get him treated appropriately and verify that there is nothing else going on to be causing these signs.
Please let me know if you have any further questions.