One the common name is pin worms.
This is not a disease it is a parasite.
That's why the vet is treating it with panacur [fenbendazole] which is a wormer that is very good at getting these.
Pin worms and hook worms can 'hide' and not show up on a fecal exam. They are usually picked up through the feet.
I repeat treatment on any dog who tests positive every two weeks to a month for at least 6 months.
These worms can all of a sudden show up in huge numbers and 'eat' all the blood in a dog - called a hemolytic crises. They can kill.
Keep after the infestation in this dog - and if other dogs have been exposed to the manure even remotely [run-off, and area that was cleaned but not sanitized etc], then treat everybody.
It's nothing to be ashamed of, but it is something you have to stay on top of.
Mimi -~-~
http://am-pugs.com -~-~ "When we stop learning we die."