100% Organic Pumpkin Seeds
Pumpkin seeds are a natural dewormer, they are part of the GOURD family and contain am amino acid called cucurbitin which paralyses parasites and expels them from the body.
They are high in fibre, a great source of calcium and promote urinary health. 
Pumpkin seeds need to be ground or cut up to release the amino acids for worm prevention. Buying whole seeds is the safest way to buy as pre-ground products have the ability to grow mould, which could be a danger to your dog. I recommend grinding up a week's worth and store in a sealed jar.
The feeding rate is 1/2 teaspoon per 10kg of body weight and feed 3-4 times a week. Feeding these as part of a natural worm prevention regime will help to naturally prevent worm burdens without the need for harsh chemicals. If you are unsure if your dog has worms, then a worm count from a poo sample can be done.