Worm Advice

How Pets and People Get Parasites

So, you’ve been introduced to the 15 most common parasites you need to be aware about. Now you need to know how your pet, and even yourself and family, can get these unwanted parasites.

Many pet owners are unsure of how these tiny, mysterious creatures end up infesting their dog or cat. A pet with a typical, everyday routine is unlikely to flag up an obvious answer as to how parasites get on or inside your pets. Knowing these details makes prevention a whole deal easier.

Generally, outdoor cats and dogs are much more likely to get parasites than indoorpets. This is because they are exposed to an environment and to other animals where parasites may be rife. Indoor pets can still get parasites, so it is important to use preventative treatments and check for parasites in your pet regardless of how often they go outdoors. Many indoor pets can contract parasites from some kind of contact with another household pet who does go outdoors, e.g. direct contact, through faeces, infested bedding, etc.

Getting fleas


  • Fleas can be caught through contact with another animal who has fleas – recurrence commonly occurs when not every animal in the household is treated or if an ‘outsider’ animal with fleas makes contact with your pet

  • Sometimes the environment is infested with fleas, either in bedding, blankets, and fabrics or even in little nooks and crannies around your home – the reason why treated pets becoming re-infested

  • When fleas lay eggs, which they do quickly and in large numbers, this contributes to further infestation

  • The presence of fleas in your home or pet means you are more at risk of being in contact with them and getting bitten, usually around the ankle

Ending up with ticks


  • Dogs are most at risk to ticks because they are more likely to be taken out for walks to explore wildlife

  • Ticks are present in undergrowth, tall grass and the wildlife kinds of places a pet would love to wander around and get stuck into, which is when and where ticks get onto the animal and burrow into their skin

  • Some people even have ticks present in their gardens, especially if you have hedgehogs.

  • People can also be affected by ticks and suffer from the same diseases ticks carry – ticks are contracted in the same way as with pets

How ear mite infestations happen

  • Pets being infested with ear mites can get them easily as they are very contagious

  • Ear mites can pass from one animal to another just through them having contact with each other

  • Due to their high level of contagiousness, ear mites easily reoccur even after treatment

  • Outdoor pets are more likely to bring home ear mites and infect other pets in the home

  • Re-occurrence is likely if you do not treat all pets in your home

  • Ear mites can live off the animal’s body for a brief period of time, so it’s possible for pets to be infested or re-infested through carpets, rugs, bedding, blankets and other similar objects your pet has had direct contact with

  • Seldom do people get ear mites from their pets

Pets being invaded by tapeworms

  • Dogs and cats are curious and like to explore and eat things they shouldn’t, so tapeworms are easily contracted by your pet ingesting a small animal that is infested with it

  • There is a higher risk of tapeworm for pets who hunt and rummage around in the wild, or dogs that reside in farms

  • Pets can also get tapeworms by ingesting fleas – fleas can carry tapeworm and often enter your pet’s system when they groom themselves

  • As both indoor and outdoor pets can get fleas, tapeworm is a risk for both indoor and outdoor animals

  • Some pets may be able to contract tapeworm by contact with raw contaminated meats or carcasses

  • Humans can accidentally ingest tapeworm eggs if, for example, they somehow swallow a flea riddled with tapeworm

Getting roundworms


  • Your pet is able to get roundworms by ingesting infested roundworm eggs that are present in the environment

  • Mothers can infect their litter through their milk when feeding and some kittens and puppies can be born with an infestation of roundworms

  • Roundworms are also contracted by cats or dogs that engage in hunting behaviour and end up digesting whole or part of an infected host – these are often birds or rodents

  • Humans can also be at risk of getting roundworms through other means, which are normally via pet faeces or soils that have been contaminated with roundworms

  • Health problems for humans with roundworm can be serious, so keep yourself, others and children away from areas where animal faeces are/have been/could be present, and always wash your hands thorough after contact with soil.

How your pet can get heartworms

  • Your pet is very unlikely to contract heartworm if residing in Britain

  • Heartworm can be contracted if you take your pet to other countries where it is present

  • Infected mosquitoes bite animals and infest them with heartworm

  • Humans can be infested via mosquitoes too, but the chances of this occurring is rare



Mosquitoes have the potential to carry heartworms and can infect animals abroad through their bite.

Animals contracting lungworm

  • Pets can get lungworm by ingesting small animals that are infected with lungworm, and these are usually snails, slugs or similar creatures

  • Although southern areas of the UK are known to have infected slugs and snails the rest of the UK is now a potential risk for lungworm

  • Pets don’t always directly eat infected hosts, but ingest the areas where they are present such as grasses, water or chewing or licking items, e.g. toys left in the garden that snails and slugs have slid over, their slime can carry the parasite

  • Lungworm is not contracted through direct contact from another animal

  • Humans are not known to be able to contract lungworm

Developing hookworm


  • Pets can get hookworm by ingesting hookworm larvae that is present in the environment

  • Almost 70% of foxes are considered to have fox hookworm, which means dogs can get the worms themselves by having contact with fox faeces

  • Hookworm can also be transmitted by the ingestion of infected creatures that have the hookworm larvae inside them

  • This larvae is also capable of piercing the skin and therefore causing an array of skin problems and infection

  • In certain countries hookworm larvae can cause skin infections in humans – this normally happens on the feet due to the lack of protective shoes

Catching biting lice

  • Biting lice are caught when one infested animal has direct contact with another

  • Biting lice on a dog is unlikely to be caught by cats, and vice versa – the lice are particular as to which hosts they live upon

  • As they are animal specific, biting lice on a cat or dog will not infest a human

  • Re-infestation can occur if other animals of the same species are not treated and items in direct contact with the infested pet are not cleaned

How pets get sarcoptic mange mites


  • Sarcoptic mange mites are caught through direct contact with another animal who has the mites

  • Due to their immensely contagious nature, they spread quickly and easily

  • Unfortunately, humans can catch sarcoptic mange mites if they have enough contact with their pet, which will end up causing skin problems when the mite burrows in your skin

Having demodex mites

  • Harmless quantities of demodex mites are actually present in the majority of cats and dogs after being passed on by their mothers and there is no need to worry about this – it is natural

  • A harmful demodex infestation occurs when your pet’s immune system is reduced due to ill health so it becomes unable to limit the amount of mites present

  • Demodex canis reside on dogs, demodex cati on cats, and humans have their very own kind for themselves, too!

Transmitting whipworm

  • Whipworm eggs are picked up in the environment and eaten by your pet, this is how they are transmitted to your pet

  • An infected animal will have the eggs present in their faeces and, if eaten by another animal that animal will become infected

  • Humans can ingest these whipworm eggs and become infected, but this seldom occurs

Being infected with fox lungworm

  • Fox lungworm is contracted by the pet consuming snails and slugs that are infected with the parasite

  • Foxes with fox lungworm can also shed the larvae for it to be picked up by your dog in the environment

  • This parasite cannot be contracted by people

The life cycles of parasites

Looking at the life cycles of parasite can show you how they infest animals and the journey they take to complete their life.


The flea: A female flea is capable of laying around 500 eggs during her lifetime. This life cycle needs to be interrupted in order to stop your pet from being infested. The cycle begins when the female flea lays her eggs. These eggs then hatch into larvae between 2 and 16 days later and these larvae survive on the animal’s blood while growing larger. When the larvae has developed further, it then forms a pupae over the space of a few weeks. Individual pupa hatch into mature fleas. This flea will need to find food and this is likely to be blood from your pet. Once the flea lands on your pet, they lay eggs and the cycle restarts. This cycle thrives in warmer environments, with a colder climate slowing the whole cycle down.

HPicture7Ticks: The tick life cycle begins by the adult tick laying eggs, of which there are typically thousands. These eggs will undergo three stages involving changes called moults – the first involves the egg turning into a larva, the second has the larva turning into a nymph, and the third has the nymph becoming an adult. At all three stages, these forms feed on lymph and blood. Some kinds of larvae and nymphs will target mammals that are small in size and feed off of them. In between moults, the two forms drop off the animal. The adult ticks are more likely to feed off larger animals, e.g. your pet! These kinds of ticks are called Dermacentor variabilis (wood tick or American dog tick) and are only found in America. Rhipicephalus sanguineus are ticks found across the globe and all stages of this tick – larvae, nymph and adult – are all known to feed off pets.

Ear mites: The life cycle of an ear mite begins with the female ear mite laying her eggs within the animal’s ear canal. It doesn’t take very long for the eggs to hatch, can be as long as three days or as short as 24 hours. This larvae develops into larva and then into a nymph until it reaches maturity as an adult. The whole cycle takes a mere 21 days to complete. These mites are caught from having direct contact from an infested animal. Such a quick cycle means many can be produced over a short period of time, explaining why they are so easily transmitted.

Lice: Unlike many parasites, the life cycle of lice occurs 100% of the time on the animal, with the host’s species being the only kind that specific lice will infest. The female attaches her eggs to the pet’s hairs. Lice eggs are called nits and they hatch between seven to 21 days. They then become adults between 21 and 28 days.

Demodex mites: The demodex mite’s entire life cycle takes place on the animal. This cycle occurs in the pet’s hair follicles, or in some cases it occurs in the sebaceous glands, or oil glands, in the skin. These mites are considered to be a natural and normal presence in the pet’s skin, with small amounts of the mite found in the majority of pets.

Sarcoptic mites: The life cycle for sarcoptic mange mites starts when a fertilised female mite gets within the pet’s skin in order to lay eggs. These eggs are laid in little channels made by the female. She will lay eggs in these channels every day for a couple of months. Once this is complete, she will die. The eggs will hatch withinfive days. The larvae burrows over a week to ten days, with a moult ultimately leading to the development of their gender. From this, the female reproduces within as little as 48 hours, sometimes taking as long as 4 days.

Heartworm: The cycle for heartworm starts off by an infected mosquito transmitting heartworm larvae into an animal through its bite. Ths larvae spreads to the animal’s body tissue and then develops into an adult heartworm. Once mature, they spread to the heart and pulmonary arteries where the females send out microfilaria into the animal’s blood. Mosquitoes, when biting and feeding from the blood, can pick this up from the blood stream, and this completes the full cycle.

HPicture8Tapeworm: The tapeworm life cycle involves a small animal ingesting the tapeworm eggs. The egg’s shell is digested which then prompts the beginning developmental step. This small animal passes on the infestation if a cat or dog hunts and eats it. Once inside the pet, further development occurs and segments are shed in the animal’s faeces. It’s this faecal matter that the small animals at the beginning of the cycle end up ingesting.

Hookworms: Many animals can get hookworms from their mother’s milk, if the mother is infested and then passes the eggs when excreting. Adult pets also ingest hookworm and pass the eggs into their faeces. Once the eggs are excreted they are in the environment and able to be picked up. Pets can become infected with the larvae by ingestion or the larvae getting into the skin, usually on the paws.

Whipworm: Whipworm larva only hatches when inside an animal. Once it does, it penetrates the large intestine wall and tissue. The eggs are excreted into the environment where they can be picked up by other animals.

Lungworm: The larvae develops in snails or slugs, which are eaten by pets. The larvae infects the animal and spreads around the body through the bloodstream to the lungs. This larvae begins to develop into adults and lays eggs. These eggs are coughed up by the animal and then swallowed backed down and digested. This then leads onto the faeces containing the larvae which is excreted out into the environment.

Roundworm: Roundworm eggs are transmitted by either ingestion of infected faeces, infection from a mother’s placenta or ingesting a mother’s infected milk. The larvae causes the pet to cough until it is coughed up and then swallowed down and digested. Worms develop fully in the gut and lay eggs. These eggs and larvae are excreted in the faeces which can then infect other animals.

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