The following is a summary of a talk given by George Leslie, Chairperson of the Trustees of CCST at a meeting for Area Reps in July 2011. It is not meant to be a scientific survey, but is more a reflection of one practising vet’s views of the ectoparasites which he is likely to see on a regular basis in very often the most unlikely of dogs.

 

The phrase “my dog’s never had fleas” is a common statement by owners who just can’t believe that their dog might pick them up somewhere or that their household might harbour one or other of the following. So let me introduce you to a few friends who do actually turn up in the most unusual places, and the significance which they have for owners of Therapets.

 

CTENOCEPHALIDES FELIS ( the Flea) is very much number one. Latin scholars among you will note that Felis means cat, and the surprising thing is that the majority of cases of fleas in dogs are caused by the cat flea, but there is a Ct. Canis as we1l. They are interchangeable, difficult to tell apart and each can live out their life cycles on a dog, cat or a fox.

 

 

 

 

 

 

 

 

 

 

 

 

                     scratches itself. If they fall off outside in normal Scottish weather the survival rate is low but in warm or humid weather a large majority survive. If they fall off inside a centrally heated and double glazed room the survival rate is about 100%

 

The eggs hatch out and produce larvae which crawl into a dark space in vegetation or deep in carpets, blankets etc where after a few days they pupate and form a sticky pupa which can survive in dry warm conditions for many months. Vibration or an increase in CO2 in their close environment (as might be caused by a dog snuffling through the grass) will cause them to hatch and the wee flea will produce a prodigious jump (almost a metre) to get onto the passing dog, and the cycle goes on.

 

Fleas are an extremely successful parasite, and are increasing year on year. They will jump onto humans where they will take 2 or 3 exploratory bites, realise that they are on the wrong species and probably fall off and mostly die. However if you have 200 fleas in a room and they all take 2 or 3 bites that’s quite a lot. Most dogs which have picked up a flea will scratch and exhibit discomfort but a minority who don’t have sensitive skins may not scratch and the owner may not realise that there is a visitor in their midst. In the case of a Therpaet such a dog may go into a are home or hospital shake itself and leave a few eggs behind. We might hope that hospital cleaning services will remove the evidence, but if they don’t guess who will get the blame.

 

Next on our list is CHEYLETIELLA (the Dandruff Mite) This is a parasite which has steadily increased throughout my professional life. It is happiest in long coated dogs but even the smoothest coat will pick them up. They are often but not always associated with heavy dandruff in the coat. In most dogs they cause intense itching so owners should notice. They will pass onto humans when you are patting them or when they rub against your legs. They do not live long on humans but in those with sensitive skins they will cause a significant rash.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Next let’s look at mange mites. These are perhaps less common than they used to be, largely because of better care for pets since they are more likely to occur in dogs whose immunity is low. The first is DEMODEX CANIS . Figure 8: Courtesy of P. Forsythe www.vetdermreferrals.co.uk It is extremely widespread but only rarely causes disease. The earliest signs of a problem will be patches of hair loss with no skin irritation on the face or legs, very often occurring in puppies at puberty or bitches who are lactating or having a phantom pregnancy. Mostly these lesions are mild and self-limiting and probably do not require treatment but every so often if your dog’s immunity is low it can become serious.

 

Can Demodex pass to humans – probably not although there is a related mite called Demodex Follicularis which is common on humans. I have however included a picture of an animal care worker with an attack of Demodex Canis – so it can happen. So once again as Therapet owners we have to be careful – areas of hair loss around the face or legs should be checked as they could represent areas of increased Demodex mite activity.

 

The second mange mite is SARCOPTES SCABEI – the cause of Scabies in humans and Sarcoptic mange in dogs. Figure 11: http://www.marvistavet.com/html/body_sarcoptic_mange.html Generally Sarcoptes in the dog produces obvious skin lesions and intense irritation but certain breeds e.g. Greyhounds and Bull Terriers appear to be able to develop a sub-clinical form. In the vast majority of cases these mites will not pass from dogs to humans or vice versa but I have actually developed a mild form of Sarcoptic mange from a dog therefore as Therapet owners we should be careful.

 

The next two exhibits in our chamber of horrors are the dog lice. The first is LINOGNATHUS SETOSIS – the sucking louse, and the second is TRICHODECTES CANIS the biting louse. Trichodectes is the more common, often seen in dogs in poor condition or in puppies from less reputable kennels. It causes skin irritation and sores and the lice are easily visible crawling slowly through the dog’s coat.

 

Linognathus is more difficult to see since they move less and often appear to be skin coloured, and over the years I have seen very few cases of this louse but they are known to grumble along at a low level for a while and then have a population explosion which can literally cover the dog. I have seen dogs with this level of infestation presented as dogs with anaemia caused by the lice sucking blood (this can also happen in dogs with severe flea infestation).In both cases the lice are fussy and do not live on humans although it is always possible that some might be transferred mechanically during patting and cause a temporary irritation in a human being.

 

The last ectoparasite which we have to worry about is TROMBICULA AUTUMNALIS – sometimes referred to in England as the Chigger and in many parts of the east of Scotland as the Berry Bug. The adult parasite lives in warm moist soil where they do not interfere with humans or animals. However in later summer they do lay eggs which develop into first stage larvae which must attach themselves and suck blood from a warm blooded animal.When dogs pick them up they normally have lesions on their feet, legs and muzzle and usually intense irritation. Humans usually pick them up from direct contact with soil or vegetation, but it is possible that a dog once infected could mechanically transfer bugs directly from their skin onto in-contact humans.I apologise for the poor reproduction of the Trombicula larva which is not as colourful as some of our other pictures. However from Jul y to September be on the lookout particularly on the east coast of Scotland.

 

Finally OTODEX CYANOTIS – the Ear Mite. This parasite is common, does not pass onto humans but is an underlying cause of a large number of ear infections in the dog. A dog with even a mild infestation could react adversely to someone fondling their ears.

 

WHAT TO DO

 

The first and most important action for the good dog owner to take is regular grooming with inspection of the coat, and particularly in long haired dogs regular shampooing. Fleas are 3-4mm long and are fast moving. They rarely jump, but do move in a higglety-pigglety fashion through the coat. Even when not seen they often leave black droppings (faeces) sticking to the coat.

 

Lice are a similar size but are slow moving. Cheyletiella are often referred to as the dandruff mite and if there is a lot of dandruff one sometimes sees the dandruff moving. However a magnifying glass does help. Trombicula are often seen as small red spots on the skin. Dogs with Otodectes will usually have waxy ears. Dogs with mange will usually have skin lesions.

 

In all cases prevention is always better than a cure, and there are numerous products on the market to deal with all of the above. Unfortunately regular prevention is expensive and there is not a one-off magic bullet that kills them all with the possible exception of Ivermectin which is not licensed for general use in this country.

 

Flea treatments are the most commonly used products purchased by dog owners. Flea collars, powders and sprays are fine but sometimes cause irritation. Spot-ons are usually more effective and less likely to cause reactions. Many spot-ons cover both fleas and ticks. Advocate Spot-on covers fleas, ear mites, many internal worms, Sarcoptes and Demodex. Stronghold Spot-on covers fleas, ear mites, Sarcops and lice and many internal worms. There is a product called Amitraz which is very effective in many situations but should only be used under veterinary supervision. Cheyletiella and Trombicula probably respond well to topical sprays particularly Frontline Spray.

 

In all cases I have to advise you to take the advice of your veterinary surgeon particularly when it comes to those parasites which are less common than for example fleas and ticks.