Deworming your dog with medication has certain risks if it is done without supervision, which is why we always recommend that you are not the one to deworm him, but that you go to a veterinarian. He may suffer side effects depending on whether he is a puppy or not, a large or small dog, or the number of parasites he has. One of them is to expel some blood while pooping, which you will see in his stools.
Anyway, that your dog makes bloody poop right after deworming him is not always associated with the medications he has taken, because this is rare. It is more likely that he swallowed something that caused a wound or that he had an illness. In any case, the solution you have to adopt is to always go to a veterinarian.
My dog is pooping blood and diarrhea, dog has bloody but acting norma...The treatment for diarrhea with blood in dogs cannot be based on home remedies. Do not ask yourself 'what can I give to him' and go urgently to your veterinarian, as it might be something serious.
How long after worming puppy are worms expelled?
Puppies are very sensitive to antiparasitic drugs, so if they start to bleed after taking them it is because the drug affected him badly; hurting him and you urgently needs to see a doctor. It can also be the case that he has so many parasites at the time of eliminating them that they accumulate in the intestinal tract, causing an obstruction and a wound, which is why the blood appears in his stools.
In conclusion, if you detect blood in the poop of your dog, you always have to go to a veterinarian. If your furry is a puppy always perform deworming under the supervision of a specialist. As a last recommendation, if he is an adult, you should also go to a veterinarian before doing it on your own. These drugs are very aggressive and cannot be administered lightly.