Immunity and prevention
Prevention is boring, cheap and unglamorous, and it is the reason most pets never see the inside of an emergency clinic.
Vaccination, in plain terms
Vaccines are divided into core — recommended for essentially every animal of that species because the diseases are severe, widespread or transmissible to people — and non-core, given based on where you live and how your pet spends its time.
| Species | Typically core | Often discussed as non-core |
|---|---|---|
| Dog | Distemper, adenovirus, parvovirus, rabies where required | Leptospirosis, kennel cough complex, Lyme |
| Cat | Panleukopenia, feline herpesvirus-1, calicivirus, rabies where required | Feline leukaemia virus, especially for outdoor cats |
| Rabbit | Myxomatosis and rabbit haemorrhagic disease in regions where they circulate | Regional variations |
| Ferret | Distemper, rabies where required | Regional variations |
Young animals get a series rather than a single shot, because protective antibodies passed from the mother interfere with the vaccine and fade at an unpredictable age. That is why the series continues to around sixteen weeks and why a booster follows some months later — not because more is better, but because you cannot know which dose was the one that took.
After the initial course, modern guidance for many core vaccines is a booster every three years rather than annually, while rabies intervals are set by law. Annual health examinations remain valuable regardless of whether a vaccine is due that year.
Fleas, ticks and worms
Parasites are not only unpleasant. Fleas cause allergic skin disease and transmit tapeworm; ticks transmit serious bacterial disease; some roundworms infect humans, particularly children. This is one area where a standing routine beats reacting to a problem.
What routine control looks like
- Use products prescribed for the species and current weight. Recheck the weight band as a puppy grows.
- Treat all pets in the household, not only the one that itches. Fleas live in the house far more than on the animal.
- Wash bedding hot and vacuum thoroughly — most of a flea population is eggs and larvae in the carpet, not adults on the pet.
- Check for ticks after every walk in long grass or woodland, and remove them with a proper tick hook rather than fingers or oil.
- Follow a worming schedule appropriate to age, diet and local risk, including heartworm prevention where it is endemic.
Wellness exams and screening
A healthy-animal appointment is not a formality. Roughly a quarter of apparently well pets have something found on a routine examination, and animals age fast enough that a year is a long gap.
- Adults: a full examination once a year
- Seniors: twice a year — a year is a large fraction of what remains
- Baseline blood and urine values while healthy, so later results have something to be compared against
- Blood pressure in older cats, which is quick and frequently abnormal
- Weight and body condition recorded every visit
Bring information the vet cannot get from the animal: what it eats and how much, water intake, any change in appetite, litter tray or toilet habits, and a phone video of anything intermittent. A ten-second clip of an odd gait or a cough is worth more than a paragraph of description.
Gut health and the microbiome
A large share of immune tissue sits in the gut wall, and the bacterial community living there is part of how the immune system calibrates itself. This is a genuinely active research area, which means it is also full of marketing claims that run well ahead of the evidence.
What is well supported: sudden diet changes disrupt the gut, so transitions should be made over five to seven days by mixing increasing proportions of the new food. Antibiotics disturb the microbiome and are worth using only when genuinely indicated. Adequate fibre matters, and for rabbits and guinea pigs, a constant flow of grass hay is not optional — their entire digestive system stops without it.
Household hygiene and shared disease
A small number of infections pass between pets and people. The risk is low and easily managed, but it is highest for infants, pregnant people, the elderly and anyone immunosuppressed — and those are exactly the households where a sensible routine is worth writing down.
- Wash hands after handling animals, litter, bedding and raw pet food.
- Scoop litter trays daily and change them out fully on a regular schedule.
- Keep food preparation surfaces separate from feeding bowls and raw diets.
- Wash bowls daily in hot water — a biofilm builds up within a day.
- Cover sandpits and clean up faeces from the garden promptly.
Why stress belongs on this page
Chronic stress raises cortisol, and sustained cortisol suppresses immune function. This is not a soft claim — it is why shelter animals develop respiratory infections during their first fortnight, and why feline idiopathic cystitis flares when a new cat appears in the neighbourhood.
Which means the mental health page and this one are the same page seen from different angles. Predictable routines, control over their own space, somewhere to hide and adequate resources — separate food, water, litter and resting places for each animal in a multi-pet home — are immune support as much as any supplement.
Common questions
Do adult pets need vaccines every year?
Not necessarily. Many core vaccines are now boosted every three years after the initial series, while rabies intervals are set by law and some non-core vaccines are annual. The annual health examination is still worthwhile even in a year with no vaccine due.
Should indoor cats be vaccinated?
Generally yes. Panleukopenia is hardy and can be carried indoors on shoes, respiratory viruses are near-universal, boarding and vet stays require proof, and an indoor cat that escapes is an unvaccinated cat outdoors.
Can I skip flea treatment in winter?
Usually not. Central heating keeps flea life cycles running year-round indoors, and tick activity now extends through mild winters in many regions. Ask your vet what the local season actually looks like.
Are 'immune boosting' supplements worth it?
For a healthy pet on a complete diet, there is little evidence they help, and some supplements interact with medication. Vaccination, parasite control, good food, weight control and low chronic stress are what measurably support immune function.