Parasites Which Cause Skin DiseaseIn small animal practice I see a large number of dogs which are suffering from itchy skin (pruritic skin). In many cases the problems are caused by external parasites, most commonly the flea.
When faced with a dog which is suffering from itchy skin I always look for external parasites which may be causing the irritation before I do any further investigations. In the vast majority of dogs suffering in this way I will find fleas are the cause of the problem. A dog with itchy or pruritic skin may be observed grooming or scratching itself excessively. Sometimes the problem is only noticed when skin rashes, hot spots or bald patches appear.
When a dog is presented to me with itchy skin, bald patches or eczema I always ask if the dog is being treated for fleas. Even if the owner has never seen fleas on the dog it is still possible that they are present and causing the dog to itch due to an allergic reaction to their bites. If your dog has bald patches of skin, especially along the back or the groin and inner thighs then always consider fleas to be a potential cause. Likewise, if your dog has eczema most vets will suggest a flea control regime be implemented regardless of whether you have seen fleas or not. (There is a very simple test which you can perform at home to check if fleas are present on your dog: Put a large piece of damp, white tissue paper under your dog. Comb your dog's coat thoroughly, especially the back and rump areas over the tissue paper. Search for brown specks of debris on the white paper which absorb water and produce a reddish ring around them. These specks are flea faeces and indicate the presence of fleas on your pet.) For much more information about fleas and their control see the section on fleas.
Although fleas are the most frequent parasites to cause pruritus (itchiness) in dogs there are a number of others which often cause problems. Ticks often cause localised itching and may also cause other problems since they are capable of spreading several diseases. For example, Lyme disease is spread by ticks. Granulomatous lesions may also form where a tick has bitten a dog.
Lice are seen less commonly than fleas or ticks. They may cause pruritus in dogs. Often the whole body is affected and some areas of inflammation and hair loss may be noticed. The lice themselves are only about 1mm in length and it is often easier to spot the eggs which are attached to the base of the hair shafts. The eggs are an off white colour and look a bit like dandruff or scurf, but they are stuck to the hair and will not come away from the shaft as dandruff would.
Various mites may infect the skin of dogs. Cheyletiella is a mite which may cause intense itching, together with dandruff and scaling skin. It seems to particularly affect the back. Otodectes cyanotis or the ear mite may also cause your dog some irritation. It sometimes causes irritation to the ear flaps as well as to the inside of the ear canal. Neotrombicula autumnalis or the harvest mite is another external parasite which may give your dog itchy skin.
There are many external parasites which cause dogs to have problems with itchy skin. The product I generally choose to control such parasites is Frontline which comes as a spot on preparation or a pump action spray. I find it very effective if it is used according to the manufacturers instructions. There are also other products on the market which are very effective against external parasites and your own vet will be able to give you more information and direct you to a product which is suitable for your pet. If your dog has very sore patches of skin or hair loss associated with external parasites then further medication to relieve the itching and also possibly to treat secondary bacterial infections may be necessary. Your vet will be able to give you further advice if your dog has a problem with its skin.
© Samantha Coe. All rights reserved. Further information, news and pet-related healthcare articles are available at vetbase.co.uk
Questions Answered
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dog skin problem (na) (12-Feb-07 07:10PM)
Edward asks:
Hi. My dog has been scratching himself lots, his skin is pink in colour. He scratches his nose just below his eyes until it draws blood, and has made his armpits ... view
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Dry skin (dog) (25-Jan-07 08:43AM)
Sam asks:
When i groom Zeus, i can feel like dry flaky skin on his back, more towards the tail, and he tends to get agitated when i brush this area, you can ... view
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Both dogs keep itching and it is driving me mad one black lab and other a boxer have been treated and also bedding and surrounding areas but can't find anything. ... view
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Be Be is a healthy 3 year old female cocker, but has flakes in her coat which I assume is from her skin? Use a nurtraderm shampoo but does not clear ... view
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skin problem (na) (20-Apr-07 09:58PM)
Tori asks:
My West Highland Terrier is scratching and rubbing the base of her tail on her back. There is nothing to see; no redness or anything. ... view
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Large red blisters appear with dry skin (dog) (28-Jan-07 03:09PM)
Elizabeth asks:
My dog's skin seems to be infected with round red blisters that dry and the skin flakes off. His skin also feels very bumpy below these blisters. Is this a ... view
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Cat skin problem (na) (01-Feb-07 01:42PM)
Emma asks:
My cat who is 8 months old has been continually scratching. I assumed it was fleas and recently got him a flea collar. However since he has had the collar his ... view
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Itching (dog) (27-Sep-07 02:00AM)
 Marie asks:
Jasper has itching on his lower back above the base of his tail. He has a large scab about 4 inches in diameter but he doesn't have fleas. What causes this ... view
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hot spots (dog) (26-Mar-07 05:41PM)
Tobi asks:
Breed: Australian shepherd-Heeler
Age: 8 years old
Issue: He's had hot spots on his abdomen/groin area for a few years now. They are now blackened. ... view
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dog chewing his leg (dog) (26-Feb-07 09:53PM)
Colin asks:
My dog will not stop chewing at one of his rear legs. He has broken the skin. I had a 'lampshade' on him for about 3 weeks at a ... view
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The skin on my royal python's belly is dry, brown and flakey and seems to be dead. ... view
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My dog has had these spots for a couple of months now and they are lumps cross spots. We are not sure if it is the new Frontline that we are ... view
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Owen asks:
Hi there,
My Northern Pine Snake hasn't gone to the toilet for almost 2 weeks. Am starting to worry about him, He has had 3 small Rats and a Chick in ... view
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Fur loss (rabbit) (01-Feb-07 04:12PM)
Rose-hannah asks:
What causes a male rabbit to lose his fur? Patches of skin are showing and fur is becoming very thin as if the rabbit is going bald? ... view
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Skin problem (dog) (03-Feb-07 10:02PM)
Sharrice asks:
We have only had these two pups for 2 weeks. They have scabs, are itching like mad and Charley has bald patches appearing on his back. ... view
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Overgrooming (cat) (26-Feb-07 09:59PM)
Michele asks:
Why is my cat over-grooming. She does not have flea problem. Have tried Feliway but she runs off. How can I cure her ... view
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Dry nose (dog) (25-Jan-07 11:07AM)
Pat asks:
Red has a dry flakey nose sometimes is this anything to worry about. ... view
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Change in behaviour (dog) (10-Feb-07 08:47AM)
Renette asks:
For the past 2 weeks my dog has been acting strange and unacceptable. He is very aggressive towards us; attacks us. He wants to hump our little jack ... view
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SKIN PROBLEM (dog) (27-Jan-07 09:44PM)
Peter asks:
Scabs under stomach area. ... view
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