Dog Heartworm Treatment

I’ve been observing white 1/4 white worm-like things in my dog’s feces. They don’t appear to be moving, and they’re not consistent. They also seem to come out of his anus at night, his bed sometimes has shriveled up little versions of them. They look like small grains of rice. I brought a sample into the vet for a fecal test, and they said he doesn’t have worms. Any ideas on what this could be?

I wanted to know what type of worm it is

I got a 12 week old puppy from the human society yesterday and they gave him a parvo shot along with his other normal puppy shots (?) and a heart worm shot. We got him home and the first hour or so he was very playful and energetic but after that he slept the rest of the day. He only ate and drank very little. During the night he threw up 2-3 times and has no other symptoms. This morning we to him to the Vet and they did a feces parvo test. It came back positive. We took him back to the humane society but they told us the parvo shot can cause the (false) positive test results. I called another animal clinic, for a second opinion, and they agreed with the humane society in that it could be just the shots effecting him and that a false positive on the parvo test is likely.
I have searched the internet and I can’t find any information on the false positive after the shots. If anybody has any information please let me know. For now we are keeping him for a couple of days to see how he feels or acts. I really want to save this dog but don’t have the money for parvo treatment.
Thanks for your help.

After we got a puppy, we both started having symptoms of aggressive cramps while defecating. We both examined our feces, and I made sure it wasn’t moving, OR worms(because we took our dog to the vet, and she had hookworms–she is done with antibiotics, and is clean of worms). My symptoms went away in 3 days. He still has his and frankly, his looks a lot more gross than mine did. Looks very white and mucus-like. I’ve done the research. I know it’s nothing something he ate, for we eat the same meals and I dont have it any more. It has been going on for about 1 week. Any suggestions? I can only assume it’s infection, or bacterial disease.

He ate a little of it before I even knew what he was doing. There are a lot of stray cats around here and I’m concerned that he’ll get worms from it. He is on Heartgard, of course, but that doesn’t cover all types of worms. Should I have him fecal tested right away, or just look for symptoms? I think some types of intestinal worms don’t have symptoms though, right? I’m confused.