Fleas, ticks and the diseases they carry: a guide to year-round prevention

Fleas and ticks are among the most common ectoparasites affecting dogs worldwide — and in tropical and subtropical regions, they are active every month of the year. Beyond the immediate discomfort of a heavy infestation, both parasites transmit diseases, some of which can be serious for dogs and, in the case of certain tick-borne conditions, for people in the household too.

The case for year-round prevention rests on two pillars: the tropical environment never gets cold enough to break the parasite lifecycle, and the diseases these parasites carry are far more difficult to treat than they are to prevent. This article covers the biology of each parasite, the diseases they carry in Singapore and Australia, and the prevention options available.

Fleas: more than just scratching

The cat flea (Ctenocephalides felis) is the most common flea species on both cats and dogs in tropical Asia and Australia. Its lifecycle has four stages — egg, larva, pupa, adult — and the environmental stages (eggs, larvae, pupae) can persist in carpets, furniture and soil for months. Only about 5% of a flea infestation is visible on the dog; the other 95% is in the environment. This is why treating the pet alone rarely resolves an infestation.

• Flea allergy dermatitis (FAD): the most common skin disease in dogs; even a single flea bite causes severe itching in sensitised dogs
• Anaemia: heavy infestations, especially in puppies or small dogs, can cause clinically significant blood loss
• Tapeworm transmission: fleas are the intermediate host for Dipylidium caninum; dogs ingest fleas while grooming and develop tapeworm infections
• Bartonella (cat scratch disease): fleas can transmit Bartonella bacteria, which can affect humans

Ticks: the disease vector risk

Several tick species are relevant to dog owners in Singapore and Australia. Rhipicephalus sanguineus (the brown dog tick) is widespread in tropical Asia and transmits canine ehrlichiosis and canine babesiosis — both potentially life-threatening. In eastern Australia, Ixodes holocyclus (the paralysis tick) produces a potent neurotoxin that causes progressive paralysis, respiratory failure and death if not treated promptly.

• Canine ehrlichiosis: fever, lethargy, weight loss, bleeding disorders; can be chronic and severe
• Canine babesiosis: destroys red blood cells, causing haemolytic anaemia; can be fatal
• Australian paralysis tick (Ixodes holocyclus): produces tick toxicosis — ascending paralysis starting with hindlimb weakness, leading to respiratory failure; emergency treatment required
• Tick-borne spotted fevers: some tick species carry Rickettsia bacteria transmissible to humans

Prevention: the options

The preventive product market has expanded significantly. Options include monthly oral chewables (isoxazolines such as fluralaner, sarolaner, afoxolaner, and lotilaner — some providing up to three months protection), monthly topical spot-ons (fipronil-based and newer actives), flea-and-tick collars (providing several months of protection), and combination products that address fleas, ticks and worms together. Not all products are equally effective against all tick species — confirm with your vet that the product you choose covers the species in your area.

• Oral isoxazolines (Bravecto, NexGard, Simparica): highly effective, fast-acting; some have a three-monthly dosing interval. Availability differs by market — in Australia these are classified as over-the-counter (OTC) products by the APVMA and can be bought at pet stores and online without a prescription; in Singapore parasiticides are generally supplied through licensed veterinary channels or on veterinary advice. Choose the right product with your vet regardless of whether a prescription is legally required in your market
• Spot-on topicals: widely available; some are waterproof; variable tick efficacy depending on species
• Tick collars: Seresto (imidacloprid + flumethrin) and similar; provide months of protection; ensure correct fitting to avoid gaps. Seresto is registered and available in both Australia (APVMA-registered) and Singapore
• Environmental treatment: for flea infestations, treat the home (vacuuming, insect growth regulators) as well as the pet

Checking your dog after walks

Even with preventive treatment, regular tick checks are recommended, particularly after walks in long grass, scrub or bush. Run your fingers through the coat, paying attention to the head, neck, ears, between the toes and around the groin and tail base. Remove any tick promptly using fine-tipped tweezers or a tick hook, grasping as close to the skin as possible without crushing the body. Do not apply petroleum jelly, heat or alcohol to the tick — these methods are ineffective and may increase the risk of pathogen transmission.