Ok, that sounds like a tapeworm. It might just be one of the sections instead of the whole thing, and it might also be a different species than the one pictured.
Well, the store bought medications are still mostly effective against round worms and tapeworms. A medication containing pryantel AND praziquantel will usually get them both. There are definitely medications which can be bought over the counter at most pet stores. Typically, the mid range cost are probably more effective than the cheaper stuff.
Now, with tapeworms though, you will want to be extra sure that you don't see any fleas. Typically, the flea is part of the life cycle of most tapeworms. The flea eats the tapeworm eggs
, then the animal eats the flea and gets the tapeworms. In most cases if it is tapeworm, you'll want to treat for fleas as well. A flea bath, and a flea preventative is a good idea to prevent it in the future.Roundworms
especially can be transmitted to children and elderly adults, or those with compromised immune systems (chemotherapy, HIV for example). So, if that fits your description, you will definitely want to get a medication that will work the first time.
There are soooooo many medications that are over the counter, and again most of them will work, but to be 100% sure probably the best thing is to take the parasite you found AND a sample of your puppies pooh and have the vet test it to be sure you get the right medication. Many of the flea preventatives that are over the counter DON'T work. So you can get that at the Vet too.
Hope that helps.