External Parasites I & II

Chorioptes bovis female

Otodectes cynotis female. The oval structure inside the mite is an egg.

Cheyletiella sp. the mites are large enough to be seen against a dark background and are commonly known as "walking dandruff'. These mites can be collected from the coat with transparent tape much like Oxyuris equi, the pin worm of equine.

Amblyomma americanum, the lone star tick. Gets its name from the white spot on the posterior edge of the scutum of the female tick.

Amblyomma maculatum, the Gulf Coast tick, male and female. Which is which?

Boophilus annulatus male and engorged female. Because this tick is the vector of Texas Cattle Fever, suspected Boophilus ticks should be submitted to a regulatory veterinarian for positive identification.

Dermacentor variabilis, the American Dog Tick, male and female. This is the most common tick of dogs in the most of North America. It is the principal vector of Rocky Mountain Spotted Fever in the United States.

• Ixodes scapularis female, ventral view. (East Coast intermediate host)
• Vector for Lyme Disease

Rhipicephalus sanguineus female and male. The Brown Dog Tick has a hexagonally shaped basis capitulum.

Otobius megnini, the Spinous Ear Tick, dorsal and ventral (top middle and bottom right) views.

Pediculus humanus humanus, the Human Body Louse. Can be found on animals.

Ctenocephalides larvae. Resemble fly maggot but can be identified by the presence of 2 antennae - like projections, called anal struts, on the posterior end.

Pulex irritans, the human flea. This flea may also be found on animals.

Gasterophilus intestinalis, an equine stomach bot. The spines are in a staggered pattern, two rows per segment, with the anterior row consisting of larger spines.

Gasterophilus nasalis, an equine intestinal bot. This species of Gasterophilus has a spine pattern of one large row per segment.

Hypoderma lineatum, the common cattle grub or ox warble. This larvae is found in the subcutaneous tissue on the back of cattle after a complex tissue migration.

Cochliomyia hominivorax, the American Screwworm in a wound. If screwworm infection is suspected, larvae should be submitted to state or federal veterinarians for identification.

Dermacentor andersoni male and female

Anterior end of Chorioptes bovis

Pediculus humanus humanus, (pediculus corporis) the Human louse species may be found on dogs and cats and must be differentiated from canine and feline lice

Otodectes cynotis male. This is the common ear mite of dogs and cats. Mites can be found by using an otoscope or by microscopic examination of material taken from the ear with cotton swab.

Otodectes cynotis female. The oval structure inside the mites is an egg.

Otobius megnini, the "Spinose Ear Tick", first nymph. Parasitize the ear canals of cattle, remaining in a particular host for as long as four months. Other animals also serve as host, as those of us in small animal clinics most commonly see this parasite in the ear of the dog.

Otobius megnini, second nymph

Heterodoxus spiniger from a dog.

Trichodectes canis is an extremely common parasite in the US and can often produce alopecia and other external symptoms in serve infestation.

Lice and eggs visible on the body surface of a cow.

Linognathus setosus (Anoplura-sucking lice) is another common species that affects dogs.

The family Pediculidae contains the human head louse and body louse of the genus Pediculus, and the human pubic (crab) louse of the genus Phthirus.

The two most common household species are Ctenocephalides felis and the less prevalent C. canis and they readily feed on dogs, cats and man. This slide shows flea-bite hypersensitivity reaction on the face of a cat.

This slide depicts and adult Ctenocephalides felis.

Eggs and feces of Ctenocephalides felis "the flea"

This illustration represents the Anopheles sp. mosquito, which carries Plasmodium falciparum (malaria)

Anopheles sp. mosquito

• Aedes aegypti or Stegomyia fasciata,
• vectors for "yellow fever"

Culex fatigans a vector of "dengue fever", filariasis and some non-human malaria's.

Typical Culex sp. breeding ground in Africa.

Tabanus ditaeniatus, the horse fly can transmit Anthrax, Anaplasmosis, Tularemia and Equine Infectious Anemia (swamp fever)

Musca domestica the house fly, resting on a host. 

This slide illustrates Haematobia irritans (the horn fly) lesions over the lateral thorax and abdomen.

• This slide shows a close up of Haematobia
• irritans lesion caudal to the scapula of a cow.

Sheep will scratch and rub their head, which will result in "broken heads" due to the irritation caused by of Haematobia irritans.

A large number of Haematobia irritans on the developing antlers of a deer on a commercial farm.

The tsetse fly, Glossina morsitans, has the most evolved mouth parts in all the family Muscidae

Shows a Hypoderma bovis larvae.

Subcutaneous encysted Hypoderma bovis "the oxwarble fly", also in this family Oestridae Hyopderma lineatum "the heelfly", are several times the size of house flies Muscae domestica.

The "screw worm or blow fly" Cochliomyia hominivorax larvae and adults surrounding a open wound in a sheep.

Numerous Gasterophilus intestinalis "bot flies" present in a horses' stomach.

Amblyomma americanum the "lone star tick" is very abundant in the southern U.S. and Central and South America. Amblyomma americanum is notorious for transmitting Tularemia, Rocky Mountain spotted fever, Q-Fever, Lyme disease, tick paralysis, and Lone Star Virus.

Amblyomma maculatum the "Gulf Coast Tick" is important in cattle. This tick occupies the Southern U.S. and South America; it likes to live in the ears making the host susceptible to Cochliomyia hominivorax infections.

• This slide shows red blood cells with Babesia sp. a tick born blood parasite.
• Left-immature neutrophils
• Right- mature neutrophils