A vet’s top tips for dealing with fleas, ticks and other parasites

Darina Schweizer

16.4.2026

Translation: Katherine Martin

Fleas, worms and ticks are lurking everywhere. Veterinarian Tobias Vögtli explains what pet owners can do about it – and when parasites become a concern in dogs and cats.

Animals are a joy to bring into your home. At least if they’re fluffy and have four legs. Having creepy-crawlies piggyback their way into your home on your cats and dogs, however, is a maddening experience.

Dr Tobias Vögtli, a veterinarian and Head of Medical Affairs at VetTrust (website in German), knows his way around the world of fleas, ticks and worms. I set up an interview to ask him all about it.

Tobias Vögtli, which parasites most commonly affect pets?
The most common ectoparasites found on the skin of dogs and cats are fleas, ticks and mites. Ones living inside the body include roundworms, hookworms and tapeworms as well as Giardia and coccidia (links in German).

I’ve heard horror stories about diarrhoea caused by Giardia. How infectious is it?
In healthy adult animals, the risk is fairly moderate. Young animals, however, get these infections relatively frequently. Their immune systems aren’t fully developed yet. Parasitic infections are especially common in animals that live in groups, for example in animal shelters or breeding facilities.

Why’s that?
In some places, hygiene standards are lower, making transmission more likely.

Speaking of transmission, where do most animals contract parasites?
Worm eggs are often found in soil, faeces or on contaminated surfaces. If animals sniff or lick them, they can become infected. Fleas are transmitted either from one animal to another or through eggs. Ticks are mainly found in grassy areas and forests.

Ticks are a good one to talk about – they can be really dangerous to humans. Is that the case for animals too?
Ticks pose a health risk to dogs. Cats don’t usually react as severely, though. They often just experience local inflammation at the site of the bite.

What illness might a dog develop after a tick bite?
They could get babesiosis (page in German), which, in Switzerland, is found in regions such as Doubs or around Lake Biel and Lake Neuchâtel. However, anaplasmosis is also relatively common (page in German).

What about Lyme disease?
Lyme disease infections do happen, but only some infected dogs show symptoms. When symptoms do develop, dogs with the disease occasionally have trouble walking and experience joint pain. Early summer meningo-encephalitis (ESME) can occur in dogs, but it’s rare overall (page in German).

Can indoor cats also be affected by parasites?
Yes. In theory, they could get infected if parasites are brought into your home on clothing or shoes.

And in practice?
Indoor-only cats are at very low risk of developing parasitic infections. That risk increases slightly if you live in a rural area and your cat has access to prey such as birds, small mammals or stray cats – for example, from a balcony. Or when outdoor clothes and shoes are worn inside the home.

How can you tell if an animal has been infected?
Worm infections usually go unnoticed. They might occasionally manifest as diarrhoea, a dull coat or an animal seeming not quite right. Most of the time, however, the symptoms don’t stand out.

In which situations are the symptoms more noticeable?
Fleas typically cause itching and skin changes. Giardia often causes diarrhoea and general unwellness. Tick-borne diseases can cause symptoms such as fever and bloody urine. Anaplasmosis and Lyme disease cause symptoms such as fever, difficulty walking or weakness.

As a layperson, I could easily get those symptoms and illnesses mixed up.
Yes, that happens a lot. Gastrointestinal illnesses, for instance, are sometimes mistaken for food intolerances, while babesiosis or anaplasmosis are sometimes incorrectly assumed to be autoimmune diseases. Skin problems caused by fleas are often mistaken for allergies. So if your pet’s experiencing skin issues, you should always rule out a parasitic infestation first.

Should you book a vet’s appointment straight away if you suspect your pet’s infected?
If they have symptoms such as fever, stomach pain or blood in their urine, yes. If it’s fleas we’re talking about, going to the vet isn’t absolutely necessary.

Why not?
Since fleas are usually visible, you can start treating the problem yourself right away. Though it’s still a good idea to ask your vet for advice over the phone. The important thing to bear in mind is that most of the fleas won’t be on your pet. If you don’t treat your furniture and blankets too, your pet will soon be reinfected.

How are intestinal parasites diagnosed and treated?
Vets either examine faecal samples under a microscope or use antigen tests. Ideally, they should analyse multiple samples to boost accuracy. If the test is positive, they deworm the animal.

I imagine antigen tests are pretty expensive…
Yes, a comprehensive diagnostic workup is usually more expensive than deworming. However, it might be worth doing to spare sensitive or anxious animals unnecessary procedures.

Many pet owners routinely deworm their pets. How often should they be doing that?
It’s recommended to deworm cats and dogs at least four times a year. However, that frequency will depend on the individual animal’s risk. Cats that hunt mice or birds should be dewormed more often, whereas indoor-only cats don’t need to be dewormed as regularly.

Are there any downsides to long-term deworming?
Side effects are rare and usually mild, such as temporary diarrhoea or vomiting. We no longer give blanket recommendations to people to deworm their pets without first determining if the treatment’s needed. Instead, it’s better to tailor a deworming treatment to the animal’s lifestyle, age and risk factors.

Isn’t it possible for animals to develop a resistance to deworming treatments?
In theory, that could be possible with frequent unnecessary treatments. However, it’s not a major contributing factor at the moment.

In supermarkets and online, you can buy tablets, spot-on treatments or collars designed to treat skin parasites. Would you recommend those?
To a certain extent. Many modern, effective medications require a prescription. Over-the-counter products vary hugely in their effects and uses. You should consult a vet when you’re deciding which one to go for. Especially if your pet has a sensitive disposition or if you have kids at home.

Why do you need to be extra careful if you have children?
They often come into close contact with pets through playing with and cuddling them. As a result, the active ingredients can get onto their hands and into their mouths via a pet’s skin or fur. Tablets are safer in that respect.

Can parasites be transmitted to humans via medications in the way you’ve just described?
Generally speaking, it’s rare – but it is possible. Fleas are the most likely culprits, since they can bite humans as well. Roundworms are worth mentioning here too; in rare cases, their larvae can migrate within the human body. Fox tapeworms mostly infect dogs that eat prey or raw slaughter byproducts. Giardia can be transmitted to humans, but only certain strains.

That’s reassuring to hear. How can you prevent human transmission in the first place?
When it comes to skin parasites, taking consistent preventative measures is crucial. Pet owners should avoid areas with high tick populations whenever possible and use preventive treatments such as spot-on solutions or tablets year-round. The same goes for fleas.

What about intestinal parasites?
Those are more difficult to prevent, as animals can easily become infected while out for a walk. It’s important to remove dog poo whenever possible and either have regular faecal exams performed or deworm your dog routinely.

Have your pets ever contracted parasites? What remedies helped? Let me know in the comments.

Darina Schweizer

Senior Editor

Darina.Schweizer@digitecgalaxus.ch

I love everything with four legs or roots – especially my rescue cats Jasper and Joy and my collection of succulents. I’m happiest following the scent of stories about police dogs and cat groomers – or cultivating thoughtful tales in garden flea markets and Japanese gardens. more

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