Fleas, ticks and other creepy crawlies

There are a number of common skin parasites of the dog including fleas, lice, ticks and mites.


What can fleas do to my dog?

Fleas are small parasitic insects that feed by sucking blood from your dog. During feeding, they inject a small amount of saliva into the skin and many dogs become sensitised (or allergic) to this resulting in intense irritation.

The severity of the irritation is related to the degree of hypersensitivity of your dog rather than the number of fleas on the body – so a very sensitive dog may suffer intense irritation even though you may not always see a flea!
The dog's response to the intense itching is to chew, lick, or scratch.  This causes hair loss and can lead to open sores or scabs on the skin, which may subsequently become secondarily infected with bacteria.

The area most commonly involved is over the rump (just in front of the tail), although all areas of the body can be affected. In long standing cases, the skin can become thickened and dark in colour. Large infestations of fleas may lead to anaemia, and fleas are also responsible for transmitting tapeworms to your pet.

How do fleas breed?

The adult fleas live on the dog and can be seen moving quickly over the surface of the skin with the naked eye. They suck blood and their droppings are small dark and comma-shaped. The female flea lays eggs and these drop off into the environment (including carpets, bedding and upholstery) together with the droppings.

The eggs hatch into larvae which then feed from the deposited droppings. Once mature, the larvae pupate and new adult fleas then emerge that can re-infest your dog. This whole life cycle can take as little as 14 – 21 days. Though your dog can become infested with fleas when contacting other infected animals, the greatest risk of infestation comes from newly emerged fleas in the environment.

How would I know if my dog has fleas?

A dog that is sensitive (allergic) to flea bites will show typical signs of intense skin irritation with self-inflicted sores and hair loss (especially along the back by the tail head). The adult fleas are small but are visible to the naked eye and may be seen moving quickly over the skin.

The characteristic comma-shaped droppings may be seen – if in doubt comb the dog’s skin so these droppings fall onto a wet white surface and they will dissolve to give a red colour.

Some people can become sensitised to flea bites, so if a family member suffers from the typical red sores, it is likely there are fleas present in the environment. Dogs that are not allergic to the flea saliva may carry fleas without scratching or showing the typical skin sores. These can be a source of infestation in a multi-pet household.

How do I control fleas?

The very nature of the flea life cycle means that your dog is very likely to come into contact with fleas in the environment. Treatments should therefore be given on a regular basis and the aim is to control the problem rather than achieve a once-and-for-all cure.

There are a wide range of products available which vary in efficacy and the way they are applied. In general they may aim to either:

  • Kill the adult fleas on the dog
  • Kill the larvae in the home environment
  • Prevent the flea eggs hatching by making them sterile

An effective flea control programme involves the use of a product (or combination of products) with a dual action – killing both the adult fleas on your dog AND the immature stages within the home environment.

It is important to treat all contact dogs and cats where possible. Your veterinarian will advise on the range of effective products available. “Off the shelf” supermarket products may not be as effective.

Does my dog need any other treatment for fleas?

Killing the fleas and controlling the larvae in the environment as discussed above is the main control method. For any allergy, avoiding further exposure is the ideal. However, because of the skin damage caused, any secondary infection may need treatment.

Your veterinarian may also advise medication to reduce the irritation and so avoid further skin damage while the flea control programme is taking effect. Your veterinarian may also suggest de-sensitisation in which an extract of flea saliva is injected into the dog in tiny amounts over a prolonged period of time.

What can Fleas do to me?

Fleas need dog or cat blood to breed. However, they can accidentally bite humans who may become sensitised to the bites. Sensitised individuals show symptoms varying from a mild rash to severe allergic reactions.


Ticks attach to the body for about 5-10 days and feed by sucking blood. They can cause a reaction at the attachment site, or anaemia if in large numbers.

They can potentially transmit a number of serious infectious diseases such as ................. This is especially a problem in Southern Europe, but is becoming a more widespread problem as pets are allowed to move more freely throughout Europe.

There are a number of products that are effective at killing ticks. In addition, some repel the ticks before they bite, and so may be preferable in areas where tick borne diseases are prevalent.


Lice crawl slowly on the surface of the skin and can be seen by the naked eye. They cause marked irritation of the skin. They are not transmissible to humans. Your veterinarian can advise on the best treatment.


Mange is a skin disease caused by tiny parasites called mites. These are not visible to the naked eye and so a microscope is needed to see them.  The two common types in dogs are sarcoptic mange and demodectic mange. It is important to differentiate them as they require different treatments a carry a different prognosis.


What causes sarcoptic mange?

Sarcoptic mange is caused by a mite that burrows just beneath the surface of the skin. This causes intense irritation of the skin such that the dog will chew and scratch constantly. Eventually, the skin will become thickened and will darken due to pigmentation. The areas most commonly affected are the belly, the legs and face (especially the ears and around the eyes). u

Is it contagious to other dogs?

Sarcoptic mange is highly contagious to other dogs and can be transmitted from foxes.  Although most common in puppies, it affects dogs of all ages. The dog's bedding should be discarded or if this is not possible, it should be regularly washed in hot water with bleach or one of the specific anti-scabies shampoos.

Is it contagious to humans?

The mite is contagious to humans, producing a distressing itchy skin condition known as scabies. However, the mites are not able to complete their life cycle on humans, so effective treatment of the dog will resolve the condition.

How is sarcoptic mange diagnosed?

Diagnosis is made by the appearance and distribution of the skin sores, and is confirmed by examining skin scrapings under the microscope and seeing the mites. However, a very few mites can cause extensive skin sores and so scrapings may sometimes appear negative.

How is sarcoptic mange treated?

There are a range of modern products that are effective against sarcoptic mange and your veterinarian can advise. Some spot-on flea products are also effective against sarcoptic mange, and in the UK where there is a large urban fox population, the use of these products as a routine might be considered appropriate.


What causes demodectic mange?

Demodectic mange ("demodex"), is caused by the demodectic mange mite, a microscopic parasite which lives in the hair follicles of affected dogs. All dogs (and many humans) have a few of these mites on their skin and as long as the body's immune system is functioning, they cause no harm.

The disease most often occurs when a dog has an immature immune system, allowing the mites to grow rapidly.  Therefore, this disease occurs primarily in dogs less than 12-18 months of age.   Adult dogs which have the disease usually have defective immune systems.

Is demodectic mange contagious?

No. Since the mite is found on virtually all dogs, exposure of a normal dog to one with demodectic mange is not dangerous. The development of clinical signs reflects depression of the immune system. This can result from genetic factors, and an affected dog usually comes from a litter containing other affected puppies. Sometimes the disease can occur as a result of treatment of the dog with immunosuppressant drugs including corticosteroids.

What are the signs of demodectic mange in the dog?

The skin usually shows areas of hair loss, especially around the eyes and face, though generally it is not itchy. The condition is called localized if there are only a few patches, and generalized if many areas of the body are affected.

How is demodectic mange treated?

Treatment is usually successful unless the dog’s immune system is defective. There are a range of effective products, though some can have side effects to your dog and yourself if used incorrectly – it is therefore very important to seek professional advice before treating.


Cheyletiella is a mange mite that lives on the surface of the skin. The dog become very itchy, but also produces an excessive amount of scurf (in fact the common name for the condition is “walking dandruff”).

How is it diagnosed?

The characteristic clinical signs are suggestive of the condition, but it is easily confirmed by examining a brushing of the scurf under the microscope when the mites are readily identified.

Is it contagious?

Yes – it is highly contagious from dog to dog, and is commonly seen in puppies where all the litter is affected. The mite is also contagious to humans, producing an itchy skin condition. However, the mites are not able to complete their life cycle on humans, so effective treatment of the dog will resolve the condition.


Ear mite infections occur most commonly in puppies. The irritation results in scratching and head shaking and there is usually a black discharge. The mites can be visualized directly using a special instrument used for looking in ears that incorporates a light and magnifying lens.

Your veterinarian can advise on the appropriate treatment.
The symptoms can result from other types of ear infection, and the damage caused by mites can also lead to secondary infection by bacteria or yeasts. It is therefore important that your veterinarian makes a full assessment before treatment is started.


“Ringworm” is a skin disease caused by a fungus and has nothing to do with a worm. There are several species of fungus involved and these may also affect humans. The fungal hyphae invade the hair follicles making them brittle so they break off at the level of the skin. This often results in circular areas of hair loss.

How is ringworm diagnosed?

Diagnosis is made initially from the appearance of the skin lesions. Some species of the fungus will fluoresce under an ultra-violet lamp. The most accurate diagnosis is made by placing hair samples in a special medium and checking for fungal growth. This process may take up to 3 weeks to get a result.

How is it transmitted?

Transmission occurs by direct contact between infected and non-infected individuals.  This includes dogs, cats and humans. In addition, fungal spores can be transmitted via inanimate objects (“fomites”) such as brushes and combs. These spores can survive for long periods in the environment.

Children are more susceptible than adults. Adult humans usually are resistant to infection unless there is a break in the skin (a scratch, etc.), or a moist area (eg under a watch strap).

How is it treated?

There are several methods of treatment, though the specific choice may depend on the severity of the infection, how many pets are involved, if there are children in the household, and how difficult it will be to disinfect your pets' environment.

In extensive cases it may be necessary to shave the dog completely as part of the treatment.
Response to treatment may take some time, and the dog may remain contagious for 3 weeks after the onset of treatment. Although a carrier state can exist, this usually occurs because treatment is not long enough or aggressive enough or because there is some underlying disease compromising the immune system.


© 2022 The Blue Dog
Website by 3RDS & wio