Why the First Eight Weeks Are a Biological Window
A puppy is born with borrowed immunity. Maternal antibodies passed through colostrum, the first milk, give a newborn temporary protection against diseases the mother has been vaccinated against or exposed to. According to research published in the journal Veterinary Immunology and Immunopathology, this maternal immunity begins to wane between six and eight weeks of age, creating a window where the puppy is increasingly vulnerable and where active vaccination must begin. The problem is that residual maternal antibodies can also partially neutralise a vaccine if it is given too early, which is why the schedule is timed the way it is, not arbitrarily, but around this immunological handover.
In India, the additional complication is disease pressure. Parvovirus, distemper, and leptospirosis circulate widely in street dog populations in most Indian cities. A puppy that goes unvaccinated past eight weeks in an environment like Mumbai, Delhi, or Chennai is not facing a theoretical risk. It is facing a near-certain one.
The Core Vaccination Schedule, Week by Week
The schedule below reflects guidelines from the Bombay Veterinary College and is broadly consistent with what most Indian veterinarians follow. Your vet may adjust timing based on the puppy's breed, weight, and local disease prevalence.- 6 weeks: First combination shot (DHPPi, Distemper, Hepatitis, Parvovirus, Parainfluenza)- 9 weeks: Second DHPPi booster plus Leptospirosis (Lepto)- 12 weeks: Third DHPPi booster, Leptospirosis, and Rabies (first dose)- 16 weeks: Fourth DHPPi booster and Rabies (second dose, completing the primary series)- 1 year: Annual boosters for all of the aboveAfter the one-year mark, most vets recommend annual boosters for Rabies and Leptospirosis, with DHPPi moving to every three years depending on the vaccine brand used (core vaccines like Nobivac and Vanguard are registered for three-year intervals in adult dogs).
What Each Shot Actually Blocks
Distemper is a morbillivirus, the same family as measles in humans, and attacks the respiratory, gastrointestinal, and central nervous systems. Puppies that survive distemper often carry permanent neurological damage: seizures, muscle twitches, and a characteristic hardening of the nose and paw pads called hyperkeratosis. There is no cure. The vaccine is the only protection.Parvovirus targets the rapidly dividing cells lining the intestinal tract, stripping them away and causing severe haemorrhagic diarrhoea, vomiting, and sepsis. A 2019 study in PLOS ONE found case fatality rates in unvaccinated puppies ranging from 30% to 91% depending on access to intensive care. In India, where 24-hour veterinary ICU access is limited outside major metros, the upper end of that range is realistic. The virus also survives in soil for up to a year, which means a puppy can contract it from a park, a building compound, or a pavement without ever making direct contact with an infected dog.Hepatitis (Canine Adenovirus Type 1) attacks the liver, kidneys, and eyes. The eye symptom, a temporary blue cloudiness called "blue eye", is actually caused by the immune response to the virus, not the virus itself. Leptospirosis is bacterial, not viral, spread through the urine of infected animals including rats. In India's monsoon season, when waterlogging is common across cities like Kolkata and Mumbai, Leptospirosis exposure risk spikes sharply. It is also zoonotic: it can infect humans.Rabies requires no introduction. Under the Prevention of Cruelty to Animals Act and various state municipal bylaws, rabies vaccination is legally mandatory for pet dogs in India. The vaccine is effective. An unvaccinated dog that bites a human triggers a public health protocol that often ends with the dog being quarantined or euthanised.
The Deworming Calendar
Internal parasites are a separate problem from the vaccine-preventable diseases, but the schedule runs in parallel and is just as critical. Puppies are frequently born with roundworms (Toxocara canis) already present, larvae can cross the placenta and infect a puppy before birth. A study published in the Indian Journal of Animal Sciences found roundworm infestation rates above 70% in puppies under three months in urban Indian shelter populations.The standard deworming protocol:- 2 weeks: First deworming (fenbendazole or pyrantel pamoate)- 4 weeks: Second dose- 6 weeks: Third dose (typically coincides with first vaccination visit)- 8 weeks: Fourth dose- Then monthly until six months of age- After six months: every three months, lifelongBeyond roundworms, Indian puppies are commonly exposed to hookworms, whipworms, tapeworms (via fleas), and Giardia. A broad-spectrum dewormer covering multiple parasite types is standard. Heartworm prevention, delivered as a monthly tablet or topical, should begin by eight weeks in regions where mosquito populations are high, which includes most of peninsular India through the monsoon months.Tick and flea prevention is not a dewormer, but it belongs in this conversation because ticks in India transmit Ehrlichia and Babesia, both of which can be fatal in puppies and neither of which has a vaccine. Monthly spot-on treatments or tick collars are the only protection.
After the Primary Series: What Ongoing Immunity Actually Looks Like
Vaccination does not create permanent immunity in every dog. Titre testing, a blood test that measures the actual level of antibodies circulating in a dog's system, can tell you whether a booster is genuinely needed or whether the dog is already protected. This is standard practice in the UK and the US and is available at several veterinary diagnostic labs in India, including Suburban Diagnostics and Oncquest. It is more expensive than a booster shot, but it avoids over-vaccination in dogs that are already immune.The annual booster visit is also the right time to check for intestinal parasites via a faecal float test, update the tick and flea protocol, and assess whether the dog's lifestyle, more time outdoors, a move to a new city, contact with street dogs, warrants adding vaccines like Bordetella (kennel cough), which is not part of the standard Indian schedule but is recommended for dogs that board, attend training classes, or visit dog parks.The schedule is not a bureaucratic checklist. Each shot targets a specific biological threat with a specific mechanism of harm. A puppy that completes the primary series on time has an immune system that has been formally introduced to its most likely killers, and has learned, at the cellular level, how to fight them.
