Core dog vaccines protect against four diseases: distemper, parvovirus, adenovirus (which causes infectious hepatitis), and rabies. These are recommended for every dog regardless of where they live or how they spend their time. Most dogs receive the first three together in a single combination shot, commonly called the DHPP or DA2PP vaccine, with rabies given separately.
The Four Core Diseases
Each core vaccine targets a disease that is widespread, highly contagious, or nearly always fatal once contracted. Canine distemper attacks the respiratory, digestive, and nervous systems and kills roughly half the adult dogs it infects, with even higher death rates in puppies. Parvovirus destroys the lining of the intestines, causing severe bloody diarrhea and dehydration that can kill within days. Adenovirus type 1 causes infectious hepatitis, leading to liver failure, and adenovirus type 2 contributes to respiratory illness. Rabies is fatal in virtually 100% of cases once symptoms appear, and because it spreads to humans, vaccination is required by law in every U.S. state.
The Combination Shot: DHPP Explained
Rather than giving four separate injections, veterinarians bundle most core protection into one combination vaccine. You’ll see it labeled DHPP, DAPP, or DA2PP on your dog’s records. The letters stand for distemper (D), adenovirus or hepatitis (A or H), parainfluenza (P), and parvovirus (P). Parainfluenza is technically a non-core component, but it’s included in almost every combination product sold.
The DA2PP version targets adenovirus type 2 specifically, which also triggers cross-protection against adenovirus type 1. In practical terms, the different labels cover the same ground. The national average cost for this combination vaccine is about $42 per dose, though prices vary by clinic and region.
Puppy Vaccination Schedule
Puppies receive their core vaccines in a series of three rounds, spaced several weeks apart. This isn’t because one dose doesn’t work. It’s because antibodies passed from the mother interfere with the vaccine in unpredictable ways during the first few months of life. Giving multiple doses ensures that at least one lands during the window when the puppy’s own immune system can respond.
The typical timeline looks like this:
- 6 to 8 weeks: First doses of distemper and parvovirus
- 10 to 12 weeks: DHPP combination vaccine
- 16 to 18 weeks: Final DHPP dose, plus the first rabies vaccine
That last dose at 16 weeks or later is the most important one in the series. Puppies vaccinated only at younger ages may still have maternal antibodies blocking a full immune response. A booster is then given one year after the final puppy dose to lock in long-term protection.
Adult Booster Schedule
After the one-year booster, adult dogs need core vaccines no more often than every three years. This applies to distemper, parvovirus, and adenovirus. Published research shows these vaccines provide a minimum of three years of immunity, and controlled studies at the University of Wisconsin found that many dogs maintain protection for seven to nine years after vaccination, confirmed by direct challenge with live virus.
Rabies boosters follow a slightly different path. The first rabies vaccine is a one-year product, meaning your dog needs a booster 12 months later. After that, most states accept a three-year rabies vaccine. Your local laws dictate the exact schedule, and rabies is the one vaccine where legal requirements override clinical judgment.
Core vs. Non-Core Vaccines
Non-core vaccines are recommended based on your dog’s lifestyle and geography rather than given to every dog universally. The most common ones include:
- Bordetella: Protects against a major cause of kennel cough. Typically recommended for dogs that visit boarding facilities, groomers, dog parks, or daycare.
- Leptospirosis: Guards against a bacterial infection spread through contaminated water that can cause liver and kidney failure, and can also infect humans. Recommended for dogs that hike, swim, or camp, though urban dogs exposed to puddles contaminated by rat urine are also at risk. The average cost is about $34 per dose.
- Lyme disease: Relevant mostly in the northeastern U.S. and other regions with high tick populations. Transmitted through tick bites and can cause lameness, kidney disease, and fever.
- Canine influenza: Recommended for dogs that travel to shows or frequently interact with unfamiliar dogs. Symptoms range from mild cough to severe pneumonia.
In areas where a non-core disease is especially common, some veterinary practices treat that vaccine as functionally core. Leptospirosis, for example, is increasingly recommended across broader regions as cases rise in urban settings.
Titer Testing as an Alternative
If you’re uncomfortable revaccinating an adult dog on a fixed schedule, titer testing offers another option. A titer test measures antibody levels in your dog’s blood to determine whether existing immunity is still strong enough to protect against a specific disease. Point-of-care test kits are available for distemper, parvovirus, and adenovirus, and they correlate well with gold-standard laboratory methods.
Both the WSAVA and AAHA vaccination guidelines support titer testing as a valid way to assess whether a dog truly needs a booster. The presence of antibodies to distemper, parvovirus, or adenovirus is a reliable indicator of protection. Some veterinarians simply follow the every-three-years schedule, while others check titers first and only revaccinate when levels drop below a protective threshold. Either approach is considered appropriate. Titer testing does cost more than a vaccine dose, so it’s worth weighing the expense against your comfort level with routine boosters.
Rabies is the exception. Because rabies vaccination is a legal requirement, most jurisdictions do not accept a titer result in place of a current vaccine certificate.
Side Effects and Safety
Serious reactions to core vaccines are rare. A large Japanese survey of over 57,300 vaccinated dogs found that 359 experienced adverse events of any kind, a rate of about 0.6%. The most common reactions were skin-related (hives, facial swelling, itching), occurring in roughly 43 out of every 10,000 dogs. Digestive symptoms like vomiting or diarrhea appeared in about 28 per 10,000. Anaphylaxis, a severe allergic reaction requiring emergency treatment, occurred in roughly 7 per 10,000 dogs. One death was recorded in the entire study.
Mild side effects like low energy, slight fever, or tenderness at the injection site for a day or two are common and resolve on their own. Smaller dogs tend to have slightly higher reaction rates than larger breeds. If your dog has had a reaction to a previous vaccine, your vet can adjust the protocol, sometimes by spacing out individual components or premedicating with antihistamines.