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External Parasites of Dogs & Cats & Prevention

Ticks and Fleas are probably the most common external parasites seen on pets. However, that is not to say that they are the only ones you need to think about controlling. Various mites, lice and flies may also deserve attention.

The threat of external parasites to your pet will vary according to your geographical location and the type of pet you own. Some of them (e.g some species of ticks) can act as carriers (vectors) of disease agents and pass that disease onto your pet, while others may not act as a vector but may themselves cause a problem (e.g. fleas).

In cats and dogs, fleas are perhaps the most common external parasite problem encountered by pet owners. Fleas have been around for a very long time and know a thing or two about species survival so getting rid of a flea problem is never easy.

Fleas   Fleas are a challenge!”

In cats and dogs, fleas are perhaps the most common external parasite problem encountered by pet owners. They have been around for a very long time and know a thing or two about species survival so getting rid of a flea problem is never easy.

Keep the following in mind when tackling fleas on your cat or dog.

They are an environmental problem, not a pet problem. Yes, you will see the fleas on your pet, but those you see are a very small proportion of the total flea population in your pet environment (approx 1% visible to you VS 99% hidden in the environment!). The implication of this is that you cannot hope to beat a flea problem by only treating the pet - you have to include the environment in your plans.

Fleas need blood meals to survive and breed. They are also photophobic (don't like bright sunlight). So that patch of sand in the middle of your garden 20m from the dogs kennel is unlikely to be the source of your flea problem. Fleas like warm, humid areas out of direct sunlight.

Dogs and cats are the preferred host for the normal pet flea (C. felis). If you have pets but find fleas jumping onto you for a blood meal then you have a huge infestation on your hands. The exception to this observation is if you move into somewhere that has not been occupied for a while then newly hatched fleas will jump on anything to get a blood meal.

One should not stop the "anti-flea" drive over winter. As it gets cooler, the flea lifecycle takes longer to complete and the presence of fleas may be less obvious. However, the lifecycle rarely stops altogether, even in very cold climates because then the pets are often inside the house with central heating.

You might not actually see any real live fleas on your pet (this is particularly true of cats because they groom so frequently). But your pet may still have a flea problem. If your dog or cat is scratching a lot and has some hair loss, especially just above the tail on the lower back, then look for little black and/or white grains in the coat. These are flea feces (black) and flea eggs (white) and their presence means that there are fleas on your pet - even if you can't see any! It doesn't automatically follow however that getting rid of the fleas will sort out the hair loss problem. Alas, it is often more complicated than that but reducing the flea load will always be beneficial to a scratching pet.

Fleas, signs of fleas, or a skin reaction to fleas may be present on a single e.g. dog in your household, while your other dogs look fine. You cannot only treat the affected animal to get rid of the fleas. You must treat all the dogs (and cats) in the household and the environment or you are going to lose the battle.

Very young animals can literally be sucked (almost) dry of blood if they have a very heavy flea burden. This can obviously be life threatening on its own, and is often made worse by a concurrent worm infestation.

What do you use to treat for fleas? By now I hope you realize there is more to this than simply buying a flea collar! There are a wide range of products available for treating both pets and the environment. Remember though that the formulations for dogs are usually different to those for cats - either in terms of the active ingredient or the dosage. Make sure you consult your Veterinarian to establish what is safe for your pet - cats can be particularly susceptible to some of the chemicals used to control fleas.

Whatever you use to treat the environment, it is best to start with a thorough mechanical cleaning before you apply any sort of chemical. Vacuuming, using only a nozzle to ensure good suction into carpet pile and cracks between floor boards, will remove a significant number of the non mobile flea eggs and pupae present in the environment. Outside, remove moist and rotting vegetation, cut the grass short and try to expose damp, shady areas to as much sunlight as possible.


While fleas can give rise to a bunch of skin problems in cats and dogs and can act as the intermediate host for a tapeworm, ticks are vectors for some nasty diseases like,Lyme Disease, Rocky Moutain Fever,  Canine Ehrlichiasis and Canine and Feline babesiasis. These diseases don't occur everywhere and so it is a good idea to find out from your vet what tick-borne diseases are present in the area where you live and what  are symptoms if your pet becomes infected.

Apart from these diseases, a tick bite can cause skin irritations in some sensitive animals and can exacerbate an existing skin sensitivity problem.

In areas where ticks occur, they are usually more of a dog problem than a cat problem simply because of the cats grooming habits. It is a good idea to check your dog for ticks after they have been out on walks, especially if they have been into the bush and walked through long grass. You might find 2 apparently different types of ticks. One will be small (the size of a match head) and flat and the other will be grey in color and often quite large (pea-sized).The first is the male tick and the second is the female after having had a blood meal.

Treatment of a tick infestation is usually less complicated than treating for fleas. If the ticks are unattached, you can simply remove them from your pet with a pair of tweezers. If you live in an area where ticks are prevalent, then regular topical products may be needed. Again, be aware that cats can be very sensitive to the various anti - tick products and therefore it is essential that you consult a veterinarian to ensure the product is safe for your pet before using it.


A:  Demodex mange
These mites are considered to be normal inhabitants of dog skin. Pups acquire the mites from the dam while suckling. Most pups will not show any clinical symptoms of infestation. However, if they do, most cases resolve before one year of age. Demodectic mange beyond that age indicates an immune deficiency.

Two forms of demodectic mange can be seen. The first is a localized form. Here one gets a small patch (or patches) of hair loss and the skin can become slightly crusty. This form can heal without treatment. The second form is a generalized form where large areas of the dog's skin is affected. This is obviously a more severe form but again, in dogs under one year, recovery can be complete.

Diagnosis is made by skin scraping and treatment can be prolonged, especially in the case of generalized demodectic mange.

Demodectic mange is rare in cats but the same general principles and descriptions apply to cats. I personally saw few cases of cats with compromised immune system.

B.  Sarcoptic mange
Again, these are far more common in dogs than in cats. They cause intense itching and are highly contagious. They are transmitted by direct contact with an infected animal or infected e.g. grooming tools. They can also be transmitted to humans and cause an intense itch and rash that is self limiting unless there is constant re-infection by contact with an infected pet.

Intensive scratching, hair loss and inflammed skin, especially on the ears, leg joints and throat, are characteristic clinical signs. Diagnosis is by deep skin scraping.


Not very common in either dogs or cats and usually associated with animals in poor condition. They can cause severe  irritation leading to scratching and hair loss. They lay eggs that look like little white grains of sand attached to the shaft of a hair. Lice are easily killed by most insecticides.


Various flies can transmit some diseases. In most pets and households though they usually represent a nuisance rather than a disease threat.  Biting flies in particular can make any animals existence miserable and for this reason alone they are worth controlling. Control measures should start with keeping the environment as clean as possible and can include a host of natural and synthetic products that you apply to the animal and/or environment.


Please remember, that whichever External Parasites you are treating, it is vital that you understand that most of the preparations you use are poisonous (otherwise they wouldn't kill the parasite!) and can harm your pet if not used correctly.

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