Parasites of Dogs and Cats Part 2: Arthropods and Protozoa

Insects  Trichodectes canis (Biting louse)  Linognathus setosus (Sucking louse)  Ctenocephalides (Flea)  Cuterebra (Rodent Bot Fly)

Trichodectes canis (Biting louse)  Found as felicola sustratus in the cat  Cause roughened hair coat, itching and dermatitis  May act as intermediate host to Dipylidium caninum

Linognathus setosus (Sucking louse of dogs)  Causes skin irritation, itching, dermatitis, alopecia, anemia, roughened hair coat  Usually transmitted by direct contact, but all life stages may be transmitted by fomites  Are species specific

Ctenocephalides (Flea)  Infest dogs and cats  Vector for Dipylidium caninum, tularemia, plague, etc.  Die at temperatures below 20 F for 48 hours or at temperatures above 120 for several days  Over 200 species of fleas worldwide  Severe infestations can cause anemia

Cuterebra (Rodent Bot Fly)  Infests rodents, companion animals and occasionally humans  Larval stage that infests skin  Acts as an irritant  Migration may be fatal  Have a cutaneous lump with a breathing hole  Use care when extracting as crushing larva may result in anaphylaxis

Arachnids  Sarcoptes scabiei (Scabies)  Demodex canis (Demodectic mange)  Otodectes cynotis (Ear mites)  Cheyletiella (Walking dander mite)  Rhipicephalus sanguineus (Brown dog tick)  Dermacentor variabilis (American Dog tick)  Amblyomma americanum (Lone Star tick)

Sarcoptes Scabiei (Scabies)  Found as Notoedres cati in cats  Causes intense itching, dry and thickened skin.  Is contagious to humans and other pets  Mites burrow under the skin so may be difficult to diagnose  Diagnose through a skin scraping  Usually have “ventral blowout”

Demodex canis (Demodectic Mange)  Rare in cats  Causes areas of alopecia on head, neck, forelimbs.  Can be localized or generalized.  Diagnosed with skin scraping.  Is not contagious  Small numbers considered normal on skin flora  Genetic predisposition

Otodectes cynotis (Ear mites)  Intense pruritis of the ear canal.  Can be found on any area of the body  Feed on epidermal debris and are easily transmitted

Cheyletiella (Walking Dander mite)  Causes mild alopecia and pruritis  May cause dermatitis in humans  Ingest keratin debris and tissue fluids  Have enormous hook like accessory mouthparts  Are visible to the naked eye

Rhipicephalus sanuineus (Brown dog tick)  Vector for canine babesiosis and canine ehrlichiosis  May cause anemia or tick paralysis when found in large numbers

Dermacentor Variabilis (American Dog Tick)  Feeds on small mammals but can also feed on dogs and humans  Vector for Rocky Mountain Spotted Fever, tularemia, and can cause tick paralysis in animals and humans

Anblyomma americanum (Lone Star tick)  Gets name from white spot on apex of scutum  Feeds on animals and humans  May be vector for Rocky Mountain Spotted Fever and tularemia.  Vector of Ehrlichia

Protozoa  Neospora caninum (Neospora)  Isopora (Coccidia)  Giardia canis (Giardia)  Toxoplasma gondii (Toxo)  Sarcocystis (Sarcocystis)

Neospora caninum (Neospora)  Transmitted transplacentally or orally  May cause ascending paralysis  A type of coccidia

Isopora (Coccidia)  Diarrhea in kittens and puppies.  May be fatal  One of most commonly diagnosed protozan disorders in puppies and kittens.  Rarely a problem in mature animals  Very small in comparison to other parasites

Toxoplasma gondii (Toxo)  May cause transient diarrhea in cats  Highly pathogenic to humans, especially fetus in utero

Sarcocystis  Not very pathogenic in cats  Very pathogenic in sheep

Giardia canis (Giardia)  Causes diarrhea  Occur as cysts or trophozoites in fecal flotation.  May also be tested for through a snap test now available.