This flea and tick season, don’t let parasites get to you – or to your pets. Lucy Jones spoke to the experts for simple advice on making a dog-owning home a pest-free zone.
The cat flea (Ctenocephalides felis) is the most common type of flea that infests dogs, cats, humans and other mammals.
There are four stages in the life cycle of a flea – egg, larva, pupa and adult. The time it takes for the life cycle to be completed is heavily dependent on weather and temperature. At 30 degrees Celsius the entire life cycle, from egg to adult, takes only two weeks.
Fleas can be a difficult parasite to eradicate because they are so well adapted to the Australian climate and because different stages in their life cycle require different treatment.
Flea eggs account for around 50 per cent of the flea population. They are white, almost round and about the size of a grain of salt. Unlike the eggs of many other insects, flea eggs are not sticky, and their smooth shells allow them to fall off their hosts into the environment.
Eggs usually hatch within one to 10 days depending on humidity, but can survive for up to two years in grass, soil, carpet, bedding, or even between floorboards. They are extremely resilient, able to survive heat, cold, drying out and household chemicals, so are difficult to kill.
Topical treatments containing (S)-methoprene can kill flea eggs on the dog and remain active for a month. In the home, aerosol ‘bombs’ containing an insect growth regulator (IGR) may be useful in preventing the eggs from hatching, and frequent vacuuming helps remove eggs. Despite containing powerful insecticides, flea treatments are safe for use on animals when used as directed.
“They work on the nervous system of the flea and, being an insect, they have a different nervous system to mammals,” explains veterinarian Dr Liia Kelman.
“It’s a lock and key system – insects have one lock and mammals have another, so the one key can’t be used to open them both.”
Newly hatched larvae are approximately 1-2mm long and will grow to around 6mm. They are segmented, transparent and white, and resemble small maggots. Larvae avoid light, so will usually be found in cracks and crevices of floors or bedding. They feed on the faeces of adult fleas, which is mainly dried blood of the host, and other organic debris.
Though they account for around 35 per cent of the flea population, larvae are highly vulnerable and can only survive in conditions of high humidity. Topical or spot-on flea treatments, rinses and sprays containing imidacloprid quickly kill larvae and adult fleas.
The larval stage usually lasts between five and 11 days, depending on the availability of food and climatic conditions. After this time, the larvae spin a protective cocoon around themselves and pupate.
Mature larvae pupate within an oval, white, loosely woven cocoon and make up 10 per cent of the flea population. The sticky outer layer of the cocoon quickly becomes coated with debris, giving it greater camouflage.
In ideal conditions pupation is complete within five to 14 days, however the adult flea may remain inside the cocoon for up to several months. Hatching is triggered by warm and humid weather, carbon dioxide emitted by animals or humans, or vibrations.
According to Dr Kelman, none of the chemical sprays available are able to penetrate the pupal cocoon. This means that adult fleas may continue to emerge from the cocoons unharmed for weeks after treatment with a chemical spray. The cocoons are also extremely difficult to remove due to their sticky coating and irregular shape; vacuuming will typically remove only 10-15 per cent from the environment.
Though they make up only five per cent of the flea population, adult fleas are responsible for the itching and irritation.
Adult fleas are 2-5mm long and dark reddish brown, and have thin, flat bodies ideal for moving through fur. They are wingless but have strong hind legs that allow them to jump up to 100 times their own body length. Upon hatching from their cocoons, adult fleas can begin feeding on their hosts in as little as seven seconds.
Adult females begin laying eggs within 36 to 48 hours of arriving on their hosts and can lay from 20 to 50 eggs a day, amounting to over 2000 in a lifetime. Untreated, an adult flea can live for up to 100 days. The key to breaking the flea life cycle is to kill the adult fleas before they can lay eggs.
Flea baths, flea powders, insecticide sprays and topical treatments are designed to kill adult fleas on your pet within 24 hours, ideally before they are able to reproduce.
Oral flea treatments are also effective on adult fleas as they are passed on via the bloodstream when the flea bites the dog. They can work in as little as 15 minutes.
In Australia, paralysis ticks (Ixodes holocyclus) are found mainly along the eastern seaboard; they prefer bushy, native terrain and long grass.
In northern parts of the country paralysis ticks can be found all year round, while in southerly areas the tick season runs from early Spring (September) to late Autumn (May).
The paralysis tick differs in appearance from other ticks. It has a light grey body, all eight of its legs originate from the front of its body, and the first and fourth pairs of legs are brown. Unfed, it is about the size of a match head, while an engorged tick swells to the size of a pea.
Paralysis ticks produce a toxin that they inject into their hosts while feeding, affecting the nerves where they join to the muscles and ultimately causing paralysis.
Symptoms may not follow a gradual progression and some animals can die suddenly in the early stages of toxicity.
Permethrin-based spot treatments kill and repel paralysis ticks on dogs. Dr Kelman advises that they must be reapplied every two weeks in tick season, compared to monthly application throughout the year, to ensure your dog has the maximum protection.
Oral preventatives are also effective but, as they enter the bloodstream of the dog and are passed on to any feeding ticks, they do require the tick to bite the dog. “No tick products on the market are 100 per cent effective,” says Dr Kelman.
“Pet owners must check their animals frequently, with daily checks during tick season or if they live in a tick prone area.”
To check your dog for ticks:
Run your fingers across its skin, moving in the opposite direction to hair growth. Check carefully all over your dog, and don’t forget folds of skin, the tops of legs, in the ears, on the tail and around the belly.
If you find a tick, remove it (see Dr Philip Brain’s tips on removing ticks, right) and continue checking your dog – there may be more than one.
The brown dog tick (Rhipicephalus sanguineus) is one of the most widely distributed ticks in the world. It is most prevalent in northern parts of Australia and is found in some inland areas of Queensland, Western Australia, New South Wales and Victoria. It is primarily a problem in the tropical and sub-tropical parts of the country, particularly during warm weather following heavy rains.
Adult brown dog ticks are flat and red-brown with tiny pits scattered over their backs. A fully engorged female brown dog tick is around 12mm in length, slow moving and can lay up to 4000 eggs after feeding, which usually hatch within weeks. Males are much smaller and actively move about.
Brown dog ticks are not as life threatening as paralysis ticks but can still cause irritating skin conditions in dogs.
Tick collars release lower doses of insecticides over time and are effective against brown dog ticks; they can provide up to five months’ control. Tick collars contain powerful chemicals and Dr Kelman recommends they be removed before swimming as they can harm aquatic life.
Also known as the scrub tick or the New Zealand cattle tick, the bush tick (Haemaphysalis longicornis) is found in the southern coastal area of Queensland, along the NSW coast and along the Murray River in north-eastern Victoria.
It can be distinguished from the paralysis tick in several ways: all pairs of legs are the same colour, the legs are finer and the mouthparts are shorter. Large infestations on an animal have been known to cause anaemia and, very rarely, death, but bush ticks are not considered particularly dangerous.
Spot treatments, rinses and tick collars are all effective against bush ticks, and repelling spot-ons will prevent their attachment.
During tick season, or if you live in a tick prone area, animals must be checked daily, says Dr Philip Brain from the Vet Specialist centre.
“Ticks will generally be found forward of the front legs, particularly on the face, neck and ears,” Dr Brain explains. “And in any areas that the dog cannot reach by biting or scratching themselves.”
If you do find a tick, Dr Brain recommends against placing any irritants such as methylated spirits, alcohol or nail polish remover onto the tick before removing – this may aggravate the tick, causing it to inject more toxin.
Try not to squeeze the tick when removing. To remove a tick place a fine pair of forceps or tweezers under the mouthparts, as close to the skin of the dog as possible and lever the tick off. Special tick removal hooks can be effective in removing the tick. It is a myth that the head of the tick must be removed or it will keep injecting poison into the dog. “Ticks have no heads, just mouthparts,” explains Dr Brain.
“If the mouthparts or feeding tube stay in the dog they will act like a small splinter and result in only a mild surface irritation before the body naturally expels them.”
Dr Liia Kelman: Veterinarian and Technical Adviser, Bayer
T: 1800 678 368
Dr Philip Brain: Small Animal Medicine Specialist, The Vet
Specialist Centre, North Ryde, NSW, and Chartered Member,
Australian Veterinary Association.
T: (02) 9888 9800