Question: Can I give my dog dried/crushed olive tree leaves to de-worm him and how much do I give him please?
Answer: You certainly can try, but the dosage would have to be found by trial and error. It may require too much making the food unpalatable.
As a starting point, for a smaller dog (up to 15 kg) give 1g per day of dried leaves. For a toy breed you could halve this.
For a larger dog (over 15kg), give 2 grams per day, increasing by 1 gram for every 15kg above this. If this is insufficient, increase by 50-100%. As leaves contain variable amounts of active constituents the results would depend on the leaves.
Two grams of leaves is very roughly a level tablespoon when broken into pieces (not crushed).