A Beagle -Shepherd ??? Well... you just HAVE to post pix of your two now with all that lead up!
Agreed ~ over the counter wormers not only don't work well AND more importantly, they can be toxic nightmares.
The other thing I wonder is whether or not his brother might be eating all his food while you aren't watching. I have a hoover for a dog
and she will happily eat everyone's food within a five mile radius if allowed. In my house Bridie (the Hoover) eats in a different room until all meals are done ~ then she's allowed to 'clean up'.