Cats and dogs provide unwitting hosts for all sorts of parasites, from fleas and ticks to various mites and worms. Happily, all can be prevented and treated with veterinary pesticides readily available from supermarkets, pet suppliers and your local vet.

But the choice is bewildering. For any given parasite there are many different treatments, and while many products treat more than one pest, none treats all, so you'll need a combination of products – ideally without doubling up.

This buying guide lists widely available parasite treatments for dogs and cats, so you can see at a glance what it treats and how to use it.

On this page:

• What's bugging your pet?
• Tablet vs spot-on vs collar vs…
• Products for cats
• Products for dogs

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What's bugging your pet?

Fleas

Fleas are most common in warm humid areas, and while more prolific in summer, they are found year-round in many parts of Australia. Flea bites cause discomfort and distress through itching, and some dogs and cats can develop hypersensitivity or an allergy. Fleas also host tapeworms, infecting your pet if they eat them. Most dogs and cats need flea treatment – indoor cats may be an exception.

Your options for flea control include tablets, chews, liquids applied to the back of the animal's neck (often called spot-ons or line-ons), sprays, collars impregnated with pesticide, powders and shampoos.

Different chemicals have different actions:

• Some treat existing fleas only, but act fast, relieving your pet's immediate misery. But new fleas can jump aboard pretty quickly afterwards.
• Some affect adult fleas when they bite the animal – so existing fleas and any new adult fleas that come along are killed.
• Some interfere with the flea life cycle, making eggs unviable.

Some products combine chemicals to do all of the above, while some products have one or two actions.

If the infestation is bad, you might start with a fast-acting adult flea killer, and use other measures for longer-term protection – ask your vet for advice. It's much easier to prevent an infestation than eradicate one, so get your control measures in place early.

In addition to your pets, you usually need to treat the whole environment, indoors and out, to get rid of them – this could be as simple as washing and vacuuming, or it may need powders and flea bombs.

Flea populations can become resistant to certain chemicals. Your vet is best placed to know about the options that will suit your local area.

Ticks

While fleas are annoying, ticks can be deadly. The paralysis tick occurs mainly in spring and summer in Eastern Australia, and is found in long grass and the bush. Tick protection isn't necessary for all dogs and cats, and depending on where you live, may not be needed all year round – your vet can advise you on the situation in your local area. No tick preventative is 100% effective, so you still need to check your pet every day.

Treatments for dogs may contain permethrin-based chemicals that are poisonous for cats, so don't use them interchangeably. Consider using a cat-safe product on your dog if you have a cat as well.

Flea and tick treatments can have side effects, especially vomiting and diarrhoea. But ticks, and sometimes even fleas, can also make your dog very sick. It's a question of weighing up the risks of the medicine versus the risks of non-treatment in consultation with your vet.

Heartworm

Heartworm is a particularly nasty parasite transmitted by mosquitoes – so even indoor pets can be affected. While dogs are the natural hosts, cats can also get heartworm, and even though they're usually not as severely affected, it can still be fatal.

Heartworm medication works by killing off the immature forms of heartworm, so it works retrospectively and must be taken continuously – most are monthly treatments, but weekly and daily treatments are available. An injectable slow-release heartworm medicine, which works for up to a year, is also available from your vet.

Lungworm

Lungworm larvae may be present in slugs and snails, and if eaten, pets may be infected with worms that make their way to the lungs, where they block airways and make breathing difficult. Most dog wormers don't claim to treat lungworm, although some cat wormers do. Research conducted internationally has found moxidectin, which is found in some heartworm treatments for dogs, to be effective against lungworm, but this claim can't be made for dogs on packaging in Australia. Check with your vet as to whether it's an issue in your area, and discuss the best preventative treatment.

Intestinal worms

There are various intestinal worms that can infect dogs and cats, with hook worms, round worms (ascarids), whip worms (mainly in dogs) and tapeworms being the main groups. Symptoms can include diarrhoea, bloody stools, weight loss, anaemia, pot belly, dry hair and/or general poor appearance. If left untreated, worm infestations can be fatal. Worms can be picked up from the mother (either in utero or via milk), from the environment (infected stools), from eating infected prey (lizard or mouse), or, in the case of tapeworms, from fleas. Worms can also be transmitted to humans.

There's no one chemical that can treat all intestinal worms – tapeworms are treated with a different chemical (praziquantel) to other worms.

Tablet vs spot-on vs collar vs…

Different forms of product may suit your pet better than others.

• Tablets can be hard to give, especially to cats. They can usually be crushed and added to food, but you need to make sure your pet eats all the food, and watch that your pet doesn't spit out or vomit up the medicine afterwards.
• If your pet swims (or is bathed) a lot, a tablet or chew may be a better option – even water-resistant products may lose their effectiveness through consistent wetting.
• Chews can work well for dogs, as long as they don't swallow them whole (break them up if that's a risk).
• Some cat medicines come in syrup form, and can be squirted straight into the mouth, or mixed into food.
• Spot-ons are good for pets that won't take medicine by mouth, but may not be a good idea if you have kids – patting or cuddling the pet without washing their hands afterwards may mean they inadvertently eat it. The chemicals may also rub off on furniture and bed clothes, again posing a contact risk for kids.
• Like spot-ons, flea and/or tick collars may also pose risks for children touching their pets.
• Given the importance of heartworm prevention for dogs, an annual dose of injectable heartworm medicine from your vet may be the best option if you're forgetful.

Cost

• While convenient, supermarkets may not necessarily be the cheapest place to buy products. Check out (online) pet supplies stores, or ask your local vet if they have generic brand products that are cheaper than big brands.
• Combination products can be cheaper than buying them separately. On the other hand, it can be difficult to compare the cost of combined products with separates, because it depends on the ingredients (for example, newer and potentially more effective flea treatments are more expensive than older ones) and the cost of supplying what's missing – there's no all-in-one that covers everything. And that's before you take the cost variations from retailer to retailer into account.
• Because of their vastly varying sizes, products for dogs come either in a standard dose size (for example, one tablet per 10kg) or different doses per tablet, according to the size of the dog. If it's a standard dose and you have a large dog, remember to take the number of tablets needed into account when you work out the cost per dose. 
• If you have two small dogs, they may be able to have half a dose each from a large dog dose, and that can save money. However, not all dosages can be safely halved – check with your vet.

Are flea, tick and worm treatments safe?

Safety is also a consideration. In September 2018 the US Food and Drug Administration (FDA) released a statement warning about the risk of tremors and seizures in animals treated with products containing drugs in the isoxazoline class, which are used to combat fleas and ticks. However, the FDA said it still considers the products "safe and effective". 

Of the products listed below, the FDA highlighted Bravetco, Nexgard and Simparica (which contain drugs in the isoxazoline class) as possible health risks.

Products for cats

Products for dogs

Stock images: Getty, unless otherwise stated.

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