External Dog Parasites: How to Identify Them

Posted by Argos, 6 January 2014, last updated 17 August 2022.

Parasites in dogs can be separated into two main categories; internal parasites and external parasites. Some types of dog parasites will cause minimal problems to your pet whereas some result in consequences that can be life-threatening. For the health and well-being of your dog it is essential that you protect your pet with appropriate and effective preventative treatments on a regular basis.

When you think of external dog parasites, you may think of fleas that cause your dog to itch and scratch themselves. But there are many other types of external parasites to be aware of.

Here, we will provide you with an overview of the common UK parasites and the potential problems they may cause. If you are travelling abroad with your dog, then you should seek further advice from your vet on the parasite risk abroad.

Vets checking dog for external parasites

What are external parasites in dogs?

External dog parasites live either on top of or within your dog’s skin. A parasite benefits by deriving nutrients at its host’s expense. Some external dog parasites may only cause superficial skin problems, but some may be carriers for other organisms that can be a problem in themselves.


In the majority of infestations, the fleas on dogs are actually cat fleas. They can be found on any dog and appear as small brown fast-moving parasites that readily jump up to 150 times their body length.

Fleas can cause severe allergies in sensitive dogs resulting in a severe itch, hair loss (mainly down the back) and often a secondary skin infection. All pets in the household must have treatment for fleas, not just the allergic ones. It is essential that the environment is also treated. Your dog is merely a restaurant to the flea, your home is the hotel where most of the life stages live. It is advisable to ensure that any pet that has had contact with fleas is wormed against Dipylidium, a tapeworm that the fleas can carry.


Lice infestations are seen most commonly in young, old and debilitated dogs. They are transmitted through contact. There are two types of lice: sucking lice which feed on blood and if severe can lead to anaemia and biting lice that feed on skin. Adults and their eggs or ‘nits’ can often be seen on the dog’s hair shafts with the naked eye. Both types of lice on dogs lead to a scurfy, dry coat and sometimes cause itchiness. Lice treatment is simple with the appropriate product, also be sure to treat the environment.


Ticks on dogs are a common type of external parasite. Ixodes are the most common types of ticks found in the UK. Dogs often pick them up whilst walking in grassland, scrub and shrubs mainly between March and November. They look like round, dark swellings attached to the skin and are often mistaken for growths.

In general, they cause only a local reaction on the skin, but they can carry several dangerous diseases, namely, Lyme disease in the UK (Erlichiosis and Babesiosis can occur in areas of Europe). A number of flea treatments will protect against ticks and care must be taken if any attempt is made to remove to ensure the mouth parts are not left behind as this can cause a reaction and possibly infection to result.

Ear mites

The most common ear mites in dogs are Otodectes cynotis, which feeds on the waxes and oils in the dog’s ear canal. Often a dark, black debris can be seen and if left untreated can lead to red, irritated and infected ear made worse by the dog’s shaking and scratching.

The three-week life-cycle can make ear mite treatment for dogs with drops lengthy and frustrating, but spot-on flea treatments are available that with some ear cleaning make the problem easy to treat provided caught early and no secondary problems e.g. infection has developed that would require veterinary treatment.


Often referred to as ‘walking dandruff’. The mite is frequently seen walking through the animals coat carrying skin scales and to the naked eye looks like dandruff on the move. Transmission is via direct contact between animals and they can bite humans often leaving small itchy, red bumps. Problems caused by the mites range from nothing to intense itching, dry flaking skin and hair loss mainly down the back. Many modern flea treatments will eliminate the cheyleytiella on dogs. All in contact pets and the environment must be treated.

Sarcoptes or scabies

The Sarcoptes mite, or the itch mite, burrows into and completes its whole life-cycle in the skin. It may affect any dog and can bite people. It results in a very severe itch and the most common sites are the ears, elbows, armpits, hocks and underside of chest/abdomen.

Many dogs will have balding ears with scaly edges that, when rubbed, are intensely itchy. Hair loss and infection quickly develop due to the scratching and prompt diagnosis and treatment is essential. Skin scrapes and blood tests can be used to diagnose. Often skin scrapes will give false negatives and the blood test results are not immediate, so treatment for dog mites is often started based on the clinical signs.

Several spot-on flea treatments can be used but veterinary attention may be required for any secondary problems e.g. infection. In areas of known cases or high fox population then regular prevention is advised as is treatment of environment/bedding as the mite can live off the dog for a few days.


The Demodex mite lives within the skin/hair follicles. Transmission is via prolonged contact e.g. from mother to pup during suckling and so the first signs of patchy baldness tend to be around the face, muzzle, forelimbs, eyes. A large number of dogs will carry the mite and show no signs but for some they cause a problem. If minor, pups will often ’grow out of the problem’ as their immune system matures. For others, and in adults, secondary infection can develop and unless dealt with medically can become severe. Sometimes in adults there can be an underlying immune system problem that makes the disease hard to treat. Diagnosis for demodex in dogs is done via a skin scrape in the consult room. Demodex mites treatment can be lengthy and require a number of repeat visits and tests. It is advisable not to breed from any dog that has suffered from Demodex. They do not live on humans.

However, some of these parasites can cause itchiness and cause/carry other illnesses (e.g. Lyme Disease) in humans, so consult your doctor if you are worried.

It is always best to regularly groom your dog and check for any kind of external parasite. The sooner you find them, the sooner you can treat your dog before severe infections or problems take into effect.

Knowing how to detect parasites in your dog is important for their health. It’s also important to protect yourself from unexpected vet bills should your dog become ill, with Argos Pet Insurance provided by Pinnacle Insurance plc. Explore our dog insurance policies today.

Share this with your friends Apple download app image Apple download app image