Why do puppies need immunizations? When they are born and breast feed from their mom, she passes some immunity to diseases to them. What is this? The mom, if she developed immunity to the diseases by getting her shots, can pass this to the puppies. But after about 6-8 weeks they will need to be immunized for several diseases that affect puppies. Then we need to give them booster shots on a regular basis. Just like little children to be vaccinated on a regular basis (I won't get into the politics of people refusing to immunize their children). Just as it is important for humans it is important for our pets. Immunizations is not the only reason one takes their pet to see the Veterinarian. Our pets need to be spayed and neutered too. But pets get problems like tummy problems, heart worms and later other organ problems. The Vet usually gives the pet a treatment for heart worms to prevent this from happening. If heart worms get into a pet, they grow and literally grow all over the heart and squeeze it. So we must nip this in the bud. Immunize before there are any signs of the illnesses. Doing this, shows your pets how much you love them and want them to be around for a long time.