💉 Vaccines and Parasite Prevention for Dogs and Cats: The Basics

When puppies and kittens get their core vaccines, how boosters work, rabies, heartworm and deworming basics, and why your vet should tailor the schedule.

Updated 2026-11-01

Read this first

This guide explains the general shape of vaccination and parasite prevention for dogs and cats so you can have an informed conversation with your vet. It is not a schedule to follow on your own. The right plan depends on age, health, previous vaccines, local disease risks, and lifestyle factors such as whether a cat goes outdoors or a dog visits daycare.

Vaccines train the immune system to recognize serious infections before the animal ever meets them. Puppies and kittens receive protective antibodies from their mother, but those maternal antibodies fade unpredictably over the first months and can block a vaccine from working while they last. That's why young animals receive a series of shots a few weeks apart rather than a single dose: the series makes sure at least one lands after maternal protection has waned.

Puppy vaccines

Core vaccines for dogs protect against canine distemper, parvovirus and infectious hepatitis (adenovirus), and in most places rabies as well. These are often combined with parainfluenza and sometimes leptospirosis in a single injection; in Korea the five-way combination is commonly called DHPPL.

A widely used approach starts the series at about six to eight weeks of age, repeats it every two to four weeks, and finishes no earlier than around sixteen weeks. Depending on lifestyle and region, vets may add vaccines for kennel cough (Bordetella), canine influenza, Lyme disease or leptospirosis if it isn't already included.

Until the series is complete, a puppy isn't fully protected, so avoid high-traffic dog areas and letting them walk where unknown dogs eliminate. Socialization is still vital during this window. Carrying your puppy to experience new sights and sounds, and arranging play with healthy, fully vaccinated dogs at home, are ways to balance the two. Your vet can help you judge the risk in your area.

Kitten vaccines

Core vaccines for cats protect against feline panleukopenia, feline herpesvirus and calicivirus, usually given together as a combination often abbreviated FVRCP, plus rabies where required or recommended. Kittens commonly start at around eight weeks, receive boosters every three to four weeks, and finish the initial series at sixteen weeks or later.

The feline leukemia virus (FeLV) vaccine is often recommended for kittens and for cats that go outside or live with cats of unknown status; for strictly indoor adults, your vet will weigh the risk. Newly adopted cats are frequently tested for FeLV and feline immunodeficiency virus before vaccination.

It's tempting to skip vaccines for an indoor cat, but panleukopenia virus survives in the environment for a long time and can be carried in on shoes and clothing. Vaccinating indoor cats with the core vaccines remains standard advice.

Boosters and rabies

After the initial series, most dogs and cats receive a booster around one year later. From then on, intervals depend on the vaccine product and local guidelines; some core vaccines are given every three years for adults, while others, such as leptospirosis, are typically annual. Some clinics offer antibody titer testing to help decide whether a booster is needed.

Rabies is a fatal disease that can pass to people, and many countries and regions legally require dogs, and sometimes cats, to be vaccinated. Puppies usually receive their first rabies shot at around three months of age. Requirements for timing and booster frequency vary by jurisdiction, so follow local law and your vet's advice. If you plan to travel internationally with your pet, proof of rabies vaccination, and often a blood titer test done well in advance, is a common entry requirement.

Mild lethargy or a small lump at the injection site for a day or two is common. Facial swelling, hives, vomiting, collapse or trouble breathing after a vaccine needs urgent veterinary attention. Booking vaccines earlier in the day lets you watch your pet afterward while the clinic is still open.

Heartworm, fleas and ticks

Heartworm is a parasite spread by mosquitoes that lodges in the heart and pulmonary arteries, causing serious and sometimes permanent damage. Prevention is far safer and cheaper than treatment. Options include monthly chewables, monthly topical products and, for dogs, long-acting injections. A blood test is usually recommended before starting or restarting prevention to confirm the animal isn't already infected.

Cats can also get heartworm disease, and because treatment options for cats are very limited, prevention matters even more. Mosquitoes find their way indoors, so indoor cats aren't automatically safe.

Fleas and ticks cause itching and skin disease and can transmit other infections to pets and sometimes people. Dogs that hike or walk through long grass need reliable tick prevention, and a quick body check after outings is a good habit. Never use a dog flea or tick product on a cat unless it's labelled for cats, since some ingredients are highly toxic to them. Which pests matter most, and in which months, depends on where you live; your vet can tell you what's common locally.

Intestinal worms and keeping records

Roundworms, hookworms, tapeworms and other intestinal parasites are common in young animals and can cause diarrhea, poor growth, a pot-bellied look and, in heavy infections, anemia. Puppies and kittens are typically dewormed several times at short intervals, and adults are treated on a schedule that reflects their lifestyle and local risks. Many monthly heartworm preventives also control some intestinal worms.

Certain parasites can infect people, children in particular, so pick up feces promptly and wash hands after cleaning litter boxes or yards. A fecal test at annual checkups can reveal parasites you would never see with the naked eye.

Finally, keep every vaccine and parasite treatment in one record, whether that's the booklet from your clinic, photos of certificates, or a note on your phone listing dates and product names. Good records make it easy to switch vets, book boarding or daycare, and prepare paperwork for travel. Set calendar reminders for upcoming doses so nothing slips through the cracks.

Health and legal notes are general information and do not replace a vet or official guidance.