Puppies are usually born with some immunity passed to them from their mothers, especially if their mothers have been properly vaccinated. Many breeders will make sure that the mother is up-to-date on her vaccinations before she is bred so she can pass along maternal antibodies to her puppies. This immunity is passed to the puppies through the placenta and when the puppies nurse from the mother within the first 48 hours and they drink some of the colostrum (the early milk that contains maternal antibodies). After the first two days the puppies will not be able to receive the antibodies from their mother’s milk.
This early immunity only lasts with puppies for a few weeks after they are born. That’s why it’s important for puppies to start getting vaccinated when they are about 5-6 weeks old. Immunity can wear off at different times for different puppies, even in the same litter. This is why puppies are given a series of vaccinations for things like parvo and canine distemper – to make sure that they are vaccinated after their immunity has worn off.
There is a time period for puppies called a “window of susceptibility” when they still have low levels of their mother’s antibodies – which can prevent a vaccination from giving them immunity – but they don’t have enough immunity to fight off a disease. During this period a puppy can get sick from parvo or one of the other diseases that are dangerous to dogs. If you have a young puppy or a litter, you need to be very careful during these weeks to make sure they are not exposed to disease. There is no way to know exactly when puppies lose their maternal antibodies and when they can get immunity from vaccinations. That’s why it’s necessary to repeat the vaccinations several times.
Ideally, puppies need to be vaccinated between about 5-6 weeks of age and 18 weeks. In most cases they will receive three combination shots during this time, followed by a booster shot when they are a year old.
The core vaccines for puppies include: distemper, canine parvovirus-2, canine adenovirus-2 (also known as hepatitis and respiratory disease), and rabies.
Other vaccines that are sometimes recommended for puppies and considered “non-core” include: leptospirosis, canine parainfluenza and Bordetella broncheseptica which cause kennel cough, coronavirus, and Borrelia burgdorferi (the cause of Lyme disease). These vaccines are not usually given to a puppy or dog unless there are circumstances which will cause them to be exposed to one of these illnesses. For instance, most dogs are not given the vaccine for kennel cough unless they are going to a dog boarding facility (where they are usually required), or some event where they will be in contact with lots of dogs that might spread kennel cough. There are lots of different versions of kennel cough (it’s like the common cold for dogs), so vaccinating against it is often not very helpful. The vaccine for Lyme disease is not always effective. It is not usually given to dogs unless they spend a lot of time in areas where there are heavy infestations of ticks. The vaccine for leptospirosis is not usually given to most dogs. It is helpful for dogs that spend a lot of time around wildlife, including drinking from water where wildlife urinates. Again, there are different versions of leptospirosis so vaccinating your dog for one strain does not protect him against others. Up to 30 percent of dogs do not respond to the vaccine.
After your dog gets his booster shots when he is one year old, many of the core vaccines for dogs are good for more than one year. Talk to your vet about how often your dog needs to be re-vaccinated for parvo, distemper, and other diseases. In most cases dogs need to get re-vaccinated every 2-3 years for these diseases but you can space the shots out so your dog doesn’t have to get all of the vaccines at one time. This can be helpful for people who are concerned about over-taxing their dog’s immune system with too many vaccinations at one time. You can get vaccinations for different diseases in alternating years.
However, every state requires dogs to be up-to-date on rabies vaccinations. Some states require yearly vaccinations and other states give you the choice of yearly vaccinations or vaccinations every three years. Check with your vet or state health or agriculture authorities to see how often rabies vaccinations are required for dogs in your state.