Vaccinations: Does My Pet Really Need Them? (Part 2)

One of the most common questions we hear from pet owners is: "My pet was vaccinated as a puppy or kitten. Do they still need boosters?" The short answer is: sometimes. Research has shown that immunity from some vaccines lasts much longer than we once believed. For many core vaccines, protection can persist for several years after the initial puppy or kitten series and the first adult booster.

As a result, modern vaccination protocols no longer recommend giving every vaccine to every pet every year. Instead, veterinarians use evidence-based, risk-based vaccination schedules tailored to each individual animal. However, immunity is not always lifelong. Some diseases stimulate long-lasting immune memory, while others require periodic boosters to maintain adequate protection. Every pet is also different — their age, health status, immune response, lifestyle, and exposure risk all influence how often vaccination may be needed. A booster may be recommended to strengthen immunity when protection may be declining, to protect animals that did not respond adequately to previous vaccinations, to help maintain herd immunity within the pet population, or to protect against diseases where immunity is known to be shorter-lived. Vaccination is therefore not a one-size-fits-all procedure — the best vaccination plan is the one tailored to your individual pet.

For dogs in South Africa, the core vaccines protect against several serious diseases. Canine Parvovirus ("Parvo") is a highly contagious viral disease that causes severe vomiting, bloody diarrhoea, dehydration, and often death, particularly in puppies. The virus can survive in the environment for many months and remains one of the most common fatal infectious diseases seen in South African veterinary practice. Canine Distemper Virus is a serious viral disease affecting the respiratory, gastrointestinal, and nervous systems — it can cause pneumonia, seizures, paralysis, and death, and dogs that survive may be left with lifelong neurological problems. Infectious Canine Hepatitis affects the liver, kidneys, eyes, and blood vessels, with clinical signs ranging from mild fever and vomiting to severe liver failure and sudden death.

Rabies is a viral disease that is almost always fatal once clinical signs develop and can infect all mammals, including humans. Because South Africa remains a rabies-endemic country, this vaccine is one of the most important for both animal and public health. Canine Parainfluenza Virus is one of the major causes of kennel cough, causing coughing and respiratory illness particularly where dogs frequently mix. Bordetella bronchiseptica is another important contributor to kennel cough and is especially recommended for dogs attending kennels, training classes, dog shows, grooming parlours, or doggy day-care facilities. Leptospirosis is a bacterial disease spread through contaminated water, rodents, and wildlife that can cause severe kidney and liver disease and may also be transmitted to humans — the risk varies according to geographic location and lifestyle.

For cats, the core vaccines address equally serious diseases. Feline Panleukopaenia ("Cat Parvo") is a highly contagious and often fatal viral disease causing severe gastrointestinal disease, immune suppression, and dehydration, particularly in kittens. Feline Herpesvirus (FHV-1) is one of the primary causes of cat flu — infected cats often become lifelong carriers and may experience recurrent flare-ups during times of stress. Feline Calicivirus (FCV) is another common cause of cat flu, with signs including sneezing, nasal discharge, oral ulcers, fever, and respiratory disease. As in dogs, rabies vaccination remains extremely important in South Africa because of the ongoing risk to both animals and humans.

Additional cat vaccines are recommended based on lifestyle. Feline Leukaemia Virus (FeLV) suppresses the immune system and increases the risk of cancers, anaemia, and secondary infections — it is primarily recommended for cats that spend time outdoors or have contact with other cats. Chlamydia felis is a bacterial infection that commonly causes conjunctivitis and upper respiratory disease, especially in multi-cat households and catteries.

Young animals receive temporary protection from their mothers in the form of antibodies. These maternal antibodies are transferred during late pregnancy and through colostrum (the first milk) after birth. While they provide valuable early protection, they gradually decline and usually disappear between 14 and 16 weeks of age. The problem is that maternal antibodies can also interfere with vaccination — if antibody levels are still high when a vaccine is given, they may neutralise the vaccine before the puppy or kitten has a chance to develop its own immunity.

Unfortunately, there is no practical way to know exactly when maternal antibodies will disappear in an individual animal. One puppy may respond to vaccination at 8 weeks of age, while another may still have protective maternal antibodies at 14 weeks. Several factors influence this, including the mother's level of immunity, how much colostrum was received shortly after birth, the order in which the puppies or kittens nursed, and the specific disease involved. This is why we vaccinate puppies and kittens several times between 6 and 16 weeks of age — the aim is to ensure that, as soon as maternal antibodies decline to a low enough level, the immune system can respond and develop long-term protection. In simple terms, the vaccination series is designed to make sure no puppy or kitten falls through the immunity gap.

Vaccination recommendations have changed considerably over the past two decades. Modern veterinary medicine has moved away from automatic annual vaccination and towards individualised, evidence-based preventative healthcare. What has not changed are the diseases themselves. Parvovirus still kills puppies. Panleukopaenia still kills kittens. Distemper still causes devastating neurological disease. Rabies remains fatal to both animals and humans. The goal of vaccination is not to vaccinate more often than necessary — it is to provide the right protection, at the right time, for the right patient. In Part 3, we will explore vaccine reactions, common vaccine myths, titre testing, natural immunity, and how veterinarians weigh vaccine risks against vaccine benefits for each individual pet.