Spring is when fleas, ticks and worm burdens all start climbing at once, and a lot of pets are under-protected without their owners realising it. Maybe the flea treatment ran out in July and nobody noticed. Maybe you moved house and didn’t factor in that you’re now in tick country. This is the time of year to actually check, not assume.
Why spring changes the risk
Fleas mature and multiply in warm, humid conditions (RSPCA Knowledgebase), which describes most of coastal Australia from September through to April. Paralysis ticks are generally found along the eastern seaboard from North Queensland down to Victoria, and in southern areas their season generally starts in spring (RSPCA Knowledgebase), especially in bushland, long grass and areas with wildlife hosts like bandicoots. Heartworm, spread by mosquitoes, also tracks warmer weather (American Heartworm Society). Intestinal worms are less seasonal but pets scavenging more outdoors in spring pick up eggs more often.
None of this means winter protection was pointless. It means the margin for error shrinks now. A missed dose in June might not matter much. A missed dose in October can matter a lot.
Step one: audit what you’re actually using
Before buying anything new, work out what’s currently protecting your pet and for what.
Check the packaging, not your memory
Find the box or the vial. Note the active ingredient, the date it was last applied, and what it claims to cover. Products vary a lot. Some spot-ons cover fleas and ticks. Some only cover fleas. Some oral chews cover fleas, ticks, heartworm and worms in one tablet. Assuming coverage because you’re “doing something” is the most common gap.
Work out the expiry date of protection
Many flea and tick spot-ons last about four weeks, though some last much longer, so check the label. Oral chews are typically monthly or three-monthly. Heartworm prevention is monthly (oral or spot-on) or twelve-monthly (injection, dogs only, vet-administered). Worming for adult dogs and cats is usually every three months, more often for puppies and kittens.
Simple audit table
| Parasite | Ask yourself | Typical protection window |
|---|---|---|
| Fleas | What product, when applied, does it cover eggs and larvae too? | Varies widely, from about 4 weeks to several months depending on product |
| Paralysis ticks | Is this actually included, or fleas only? | Can differ from the flea cover interval, check the label for paralysis tick cover specifically |
| Heartworm | Monthly tablet/spot-on current, or annual injection due? | 1 month or 12 months |
| Intestinal worms | Last dose date, covers roundworm, hookworm, whipworm, tapeworm? | Usually every 3 months for adults |
Common gaps owners don’t notice
- Using a flea-only product and assuming it covers ticks. Many budget supermarket options do not.
- Cats on a dog product’s schedule but the cat formulation is different strength, always check the label matches the species.
- Indoor cats skipped entirely. Fleas still hitch rides in on humans and other pets, and mosquitoes get indoors too.
- Heartworm prevention lapsed after a house move or a busy few months. Once doses are missed, you generally need to restart prevention promptly and your vet may recommend heartworm testing, because an infection can’t be detected until the worms are about seven months old (American Heartworm Society).
- Treating for fleas but never treating the house or yard, so the cycle keeps going.
- Multi-pet households where one animal gets treated and another (often the cat, or a second dog) gets forgotten.
Location matters more than most people think
Where you live and where you walk changes the actual risk, not just the general one.
Tick zones
If you’re in a paralysis tick area (coastal NSW, southeast Qld, parts of Victoria), a product that only mentions “ticks” broadly might not name paralysis ticks specifically, or might need a shorter reapplication interval for tick cover than for flea cover. Daily hands-on tick checks in spring and summer are worth doing regardless of product, run fingers through the coat, check ears, lips, between toes and around the collar. Most ticks are found forward of the front legs (RSPCA Knowledgebase).
Heartworm-prone areas
Heartworm risk tracks mosquito activity, so it’s higher in northern and coastal regions and lower but not zero further south and inland. Dogs that travel with owners to different climates need cover that matches wherever they’ve actually been, not just home.
Urban vs rural and bush-adjacent
Dogs walking daily through long grass or bushland pick up ticks and worm eggs more than dogs on footpaths. Cats with outdoor access in bush-adjacent suburbs face similar tick exposure to dogs, even though tick products for cats are less commonly discussed.
What a proper spring plan looks like
Match the product to all four parasites
Some all-in-one products cover fleas, ticks, heartworm and intestinal worms in one monthly dose. Others need two or three separate products layered together. Either approach is fine, the point is knowing which you’re running and confirming nothing has fallen through a gap between products.
Set actual reminders
Phone calendar, app, or a note on the fridge. Monthly products are the ones most often forgotten because four weeks slips past quietly. A dose that’s a week or two late isn’t a disaster, but it does open a window.
Rough cost expectations
Prices vary with the product, pack size and your pet’s weight, and bigger packs usually work out cheaper per dose. Separate products (a spot-on plus a worming tablet) can work out similar or slightly less, but require you to track two schedules instead of one.
If you’re not sure what’s suitable
- Bring the current product packaging to your vet clinic and ask them to confirm what it does and doesn’t cover.
- Mention where you live and where the pet is walked or allowed outside.
- Ask specifically about paralysis tick cover if you’re in a risk zone, don’t assume it’s included.
- For cats, confirm the product is cat-specific. Some dog flea and tick products are highly toxic to cats and can kill them (RSPCA Knowledgebase).
- If a dose has been missed for longer than the product’s stated gap, ask whether a heartworm test is needed before restarting.
Signs of a parasite problem worth acting on
- Scratching, hair loss or small black specks in the coat (flea dirt) that stain red on a wet tissue (RSPCA Knowledgebase).
- A swollen, painful tick site, wobbliness in the back legs, or a change in bark or meow (paralysis tick signs, dogs mainly but cats can be affected too).
- Visible worms or segments (like grains of rice) around the tail or in faeces.
- A mild persistent cough, tiring on walks or reduced appetite, which can suggest heartworm in dogs (American Heartworm Society).
These signs can have several causes, not just parasites, so they’re a reason to get the pet examined rather than to self-diagnose.
When to call a vet
Call straight away if your dog shows wobbly back legs, a change in voice, vomiting or difficulty breathing, these can be signs of paralysis tick toxicity and are a genuine emergency, not a wait-and-see situation. Cats with sudden lethargy, laboured breathing or collapse after being outdoors also need immediate attention. Book a routine appointment if you find fleas despite treatment, notice worms in faeces, or you’re unsure whether your current products actually cover ticks and heartworm for your area. If a preventative dose has lapsed by more than the label’s stated window, call the clinic before just resuming the schedule, they may want to test first.
