External Parasite CD I

Hookworm Dermatitis of a Siberian Husky confined to a dirt based run and affected with Ancylostoma caninum shows lesions of chronic hookworm dermatitis on all feet. There is alopecia, erythema, swelling and crusting.

Cuterebra palpebral fistula in the neck of a Persian kitten.

• Cuterebra 
• The larvae from before, removed from fistula.

Eye of 6 wk German Shepherd dog with circular, ulcerated lesion below the lower lid. This is the mouth of a fistula containing cuterebra larvae. The mouth parts of the larvae can be seen as two dark objects in the center.

• The 18 mm larvae can be seen after it has been pulled off of its cyst-like fistula.
• Notice the wound after surgical enlargement.

Only whitish scar remains after the wound had healed without lid malformation.

Fly Dermatitis on a German Shepherd dog's pinna. Hemorrhagic crusts from oozing serum and blood results from the rasping mouth parts of stable flies.

• A. Fly Dermatitis on a German Shepherd dog's pinna
• b. Otitis externa on a dog. There is edema, erythema and purulent exudation.
• c. Dark brown, waxy exudate and crusts in the ear of a dog with ear mites. (Otodectes cynotis)
• d. Filmy adherent crusts characteristically form in rabbit's ears infected with ear mites. (Psoroptes cuniculi)

Lice - Linognathus setosus (adult male)

Lice - Linognathus setosus (adult female)

Flea - Ctenocephalides felis adult

Adult flea - Ctenocephalides felis on human skin

Adult female flea - Ctenocephalides felis. Note the orange color.

Ctenocephalides felis head and pronotum showing one antenna and the genal and pronotal combs.

• Stages of life cycle (right to left)
• Adult female with egg, adult mate, mature larvae ready to pupate (white), young larvae after 15th blood meal (Red). The pupa is not illustrated.

Chronic flea allergy dermatitis in a Pekingese, showing alopecia, hyper pigmentation and cutaneous hypertrophy on the lower back and tail head.

• Flea Allergy Dermatitis
• After many sessions of affliction, area of the lower back and tail becomes hairless, thickened, gray and folded.

Macrophotograph of white flea eggs and dark brown fecal crusts on a piece of blue paper. Newly hatched flea larvae find the available fecal crusts a handy source of food.

Numerous miliary flea allergy lesions (Miliary Dermatitis) clustered on the back of this cat.

Other common sites of the miliary lesions are the neck and throat.

Flea Allergy Dermatitis (canine) distribution pattern; back and stomach.

Microscopic appearance of adult, larva and egg stages of Cheyletiella yasguri (one about to hatch)

Tongue depressors parting hair on mid-back of corgi puppy showing Cheyletiella yasguri "walking dandruff'

Hair parted with Cheyletiella yasguri

Adult female Trichodectes canis

Localized demodicosis. A single alopecia patch at the commissure of the lips.

Generalized pyogenic demodicosis. Distribution of the lesion in a rapidly advancing case.

Demodicosis in a cat. Only the eyelids and periocular area are affected. Infections with Demodex cati are usually mild.

Localized demodicosis distribution pattern

Generalized demodicosis distribution pattern

Chihuahua showing extensive erythema, alopecia and crusting typical of generalized demodicosis with pyoderma.

• Whippet with acute pyodermas of face, lips, and
• eyelids. Secondary to generalized demodicosis.

Typical distribution of lesions of face and extremities, generalized demodicosis.

Egg of Demodex canis

Demodex canis- two adults. Note 4 pairs of developed legs.

Adult and larvae of Demodex canis - three pairs of stubby legs

Nymph of Demodex canis- 4 pairs of stubby legs

Adult and immature forms of Demodex canis

The margin of ear (pinna) is a characteristic site. (Demodex canis)

Erythematous papules above the belt line characterize the temporary invasions of human skin by Sarcoptes scabiei var. canis

Canine scabies distribution pattern

Sarcoptes mites and an egg. Small brownish pellets are the mites' fecal material.

Adult Sarcoptes scabiei var. canis

Eggs of Sarcoptes scabiei obtained from a mineral oil scraping from the ears' pinna of a dog with canine scabies. Note the legs of the developing larva within the egg in the center. Dark fecal pellets from adult mites can be seen touching the egg in the center. Positive diagnosis of scabies can be made from finding these eggs.

• Canine scabies for weeks after onset in a Japanese Spaniel. Fourteen dogs in a kennel were affected. This illustrates the typical distribution pattern.
• Pic 2 = Close view of the same patient showing areas on the elbow where diagnostic skin scraping was made. The typical popular "rash" is well illustrated in this view.

• Dry crusted lesions on the edges of the ears and face are typical of feline scabies.
• Pic 2 = Thickened skin with dry, adherent crusts shown on the area clipped of hair for better visualization.

Dry crusted gray lesions on the skin of the elbow of an ocelot

Feline scabies distribution pattern

Adult Notoedres cati. (Feline Scabies) Note that this mite is somewhat smaller than Sarcoptes scabiei.

Otitis externa in a dog. There is edema, erythema and purulent exudation.

Dark brown waxy exudate and crusts in the ear of a dog with ear mites - Otodectes cynotis

Larger male of Otodectes cynotis

Nymph of Otobius megnini the spinous ear tick

• Rear legs and hindquarters of beagle with Pelodera Dermatitis. The involved areas are alopecia and erythema.
• Pic 2 = Ventral chest and abdomen of patient Bloody areas are sites of skin scrapings

• Lateral hock and thigh of patient with Pelodera Dermatitis.
• Pic 2 = Close view of skin of patient showing intense erythema, multiple pustules and alopecia.

Pelodera strongyloides a free living nematode. This parasite larvae resembles the hookworm larvae.

Angio-neurotic Edema an anaphylactic reaction seen with vaccines and bee stings.

Sarcoptes scabiei male, the "itch" mite of dogs

Notoedres cati, the sarcoptic mange mite of cats.

Notoedres cati

Chorioptes bovis male. Very similar in appearance to Psoroptes.