1. External Parasites of Dogs, Cats, and Large Animals

2. External Parasites of Dogs and Cats (Arthropods)
Parasites with jointed appendages or feet
Acarines (Mites)
Sarcoptes scabei (scabies mites)
Otodectes cynotis (ear mites)
Demodex cani (hair follicle and sebaceous gland)
Cheyletiella parasitivorax (walking dandruff mite)
Trobicula (chiggers)
Ticks (acariasis; otoacariasis; 1-host; 3-host; many-host)
Relative to veterinary parasitology, arthropods include a wide variety of creatures with “jointed feet,” such as centipedes, millipedes, crustaceans, insects, and mites and ticks.

3. Sarcoptes scabei (Scabies)
Diagnosed by superficial skin scraping on glass slide containing a drop of mineral oil
At the end of some of the legs is a long, unjointed pedicel (straight stalk) with a tiny sucker on its end
Deep skin scraping, adult Sarcoptes scabei mite.

4. Demodex canis Deep skin scraping and microscopic identification
Unique morphology
Carrot-shaped; resembles an eight-legged alligator
Predilection site: long, thin, confining hair follicle
Deep skin scraping, adult Demodex canis, the follicle mite of dogs.

5. Cheyletiella parasitivorax
Walking dandruff mite
Intense pruritis; puppies, kittens, and humans; less intense in rabbits
Highly contagious
Topical and systemic treatment
Adult mite, Cheyletiella parasitivorax, “walking dandruff.”
Mites are approximately 0.5 mm in length, with a unique appearance—a bell pepper shape, with a pair of accessory hooks on capitulum (head).
At the end of each leg is a tiny comb-like structure.

6. Trombicula (Chiggers)
Warm-blooded animals, both avian and mammalian
Parasitic stage: six-legged larval chigger
Feed off host skin and drop off; they do NOT burrow in
After dropping, molt into free-living eight-legged nymph
Therapeutic shampoos
Shown here: Six-legged larval Trombicula species. The larval chigger is the only parasitic stage in the life cycle of this ectoparasite.

7. Ticks Thousands of different species
Affect almost every species of warm-blooded animal (mammals and birds)
One-host ticks
Two-host ticks
Three-host ticks
Many-host ticks
See Table 14-2 for characteristics of common tick-borne diseases.
Dogs are very susceptible to tick bites and tick-borne diseases.
Important to use tick preventative product on dogs.
When removing a tick from the pet's skin, it is important that residual tick mouthparts not be left behind or secondary infections may result.

8. Ticks
Although ticks are commonly thought of as insects, they are actually arachnids similar to scorpions, spiders and mites. All ticks have four pairs of legs for a total of eight legs as adults and have no antennae. Adult insects by comparison have three pairs of legs (6six total legs) and one pair of antennae. Ticks are parasites that feed on the blood of their host, which can be an animal or a human.

9. Ticks
Ticks are efficient carriers of disease because they attach firmly when sucking blood, feed slowly and may go unnoticed for a considerable time while feeding. Ticks take several days to complete feeding.
Because cats are fastidious groomers, it is rare to see more than one or two ticks on a cat. If you observe numerous ticks, this could be a sign of illness in your cat (cats that are ill usually don't groom themselves).

10. Different Types of Ticks
What are the different types of ticks?
There are two groups of ticks, sometimes called the "hard" ticks (Ixodidae) and "soft" ticks (Argasidae). Hard ticks, like the common dog tick, have a hard shield just behind the mouthparts (sometimes incorrectly called the "head"); unfed hard ticks are shaped like a flat seed. Soft ticks do not have the hard shield and they are shaped like a raisin. Soft ticks prefer to feed on birds or bats, and are seldom found on dogs or cats.
Although there are at least 15 species of ticks in North America, only a few of these species are likely to be encountered by your cat. They include the:
1. American dog tick
2. Lone star tick
3. Deer or Blacklegged tick
4. Brown dog tick
Other tick species may be encountered in various regions. Ask your veterinarian if you need additional information about a specific species.

11. External Parasites of Cattle
Types of External Parasites
Ticks
Mites
Flies
Lice
Bots

12. Ticks Hosts 2 types All types of livestock
Major threat to cattle and horses
2 types
Soft ticks: outer shell is soft
Feed rapidly and then leave host.
Hard ticks: outer shell is hard
Feeds slowly and takes a large meal.
Drops from host to lay eggs.

13. Ticks Hard Shell Ticks Lone Star Tick: in wooded and brushy areas.
Problem in the spring and summer
Gulf Coast Tick: found in gulf coast area
Problem in late summer and early fall

14. Ticks Soft Shell Ticks Life Cycle
Spinose Ear Tick: Attaches deep within the ear
Not a problem in Texas, it is a big pest in other states.
Life Cycle
Adults lay eggs that hatch into larvae
Larvae find hosts such as birds
Larvae becomes Nymphs
Nymphs attach to host (Livestock) and become adults

15. Ticks
Damage
Cause inflammation, itching, and swelling at the site of the bite.
Ticks suck animals blood which can result in anemia, weight loss, and even death.
Ticks can also create wounds that can become infected if not taken care of.
Spread diseases.

16. Ticks Symptoms Usually found by visual inspection.
Livestock will rub on objects, and sometimes carry their heads in an unnatural position.
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17. Mites Hosts: All livestock 2 Types Life Cycle
Surface mites- Stay on the surface of animal
Burrowing mites-Burrow into the skin
Life Cycle
Spend entire life on host
Adult lays eggs that hatch into larvae
Larvae molt & become nymphs
Nymphs molt and become adults

18. Mites
Damage
Hair comes out and skin can become rough and crusty.
Also can be called mange or scabies
Symptoms
Falling hair and rough, red skin can become visible.
Animals will scratch on anything

19. Lice Hosts: All species of livestock
There is only one species that affects swine.
Spread by animal to animal contact
2 types
Sucking lice- larger and take blood meals
Biting Lice- feed on dead skin and feathers

20. Lice Hogs Sheep Hog Louse- Only species that feeds on hogs
Sheep Biting Louse
Sheep Sucking Body Louse
Sheep Foot Louse
Hog Louse

21. Blowfly (screwworm) Hosts: All livestock Blowfly: the adult stage
Screwworm: larval stage
Life Cycle
Blowfly lays eggs around and on wounds
Eggs hatch into larvae or maggots (which feed on living flesh)
Larvae drop to ground & burrow in soil & pupate
Flies emerge after pupal stage

22. Blowfly (Screwworm) Damage Symptoms Causes weight loss
Permanent injury
Death
Symptoms
Unpleasant odor from wound
Enlargement of wound
Seepage of blood from the wound

23. Cattle Grub (Heel Fly)
Host: Mainly cattle, but they have been found on other species of livestock
Emerge in late winter, spring, or summer
Mainly a nuisance to cattle

24. Cattle Grub (Heel Fly) Life Cycle Adult fly lays eggs on hairs of legs
Eggs hatch into larvae which penetrate into the hosts body
Migrate until they reach the back
Grubs cut breathing holes & feed on fleshy skin
Reach maturity & burrow through the hide and drop to the ground
Grub goes into the ground and pupates
Fly emerges

25. Cattle Grub (Heel Fly) Damage Symptoms
Can cause economic loss from hide damage and decreased milk production.
Decreased amount of feeding time
Symptoms
Cattle run from the flies
Visible swelling of the grubs on the back of the animals

26. Horn Fly Host: Mainly cattle, but will attack other species.
Mainly a nuisance
Blood sucking species
Life Cycle
Female lays eggs in manure
Hatch into larvae that mature and pupate
Young flies emerge and become adults quickly

27. Horn Fly Damage Symptoms
Bites and sucks blood from the back, neck, head, and belly of the host
Can result in transmission of disease
Annoys the animal causing weight loss
Symptoms
Can be easily seen on the animals
They can cover an animal in the spring and summer

28. Other Flies Hosts: All species of livestock Other flies include
Horsefly
Stable Fly
Housefly
These flies bite and suck blood from the animals
Mainly a nuisance to animals

29. Horse Bots
Hosts: Horses only
Closely related to the heel fly

30. Horse Bot Life Cycle Adult fly emerges from pupae in feces
Females lay about 500 eggs on hairs of horses legs, stomach, neck, and chin.
Horse rubs or bites areas infected which stimulates hatching
Larvae enter mouth & migrate to the stomach
Larvae attach to stomach wall & mature
Mature larvae pass out of animal into feces

31. Horse Bot Damage Symptoms Can cause anemia
Reduce digestion when bots infest the horses stomach
Causes irritation to the horse
Fly is easily seen
Loss of weight
Sometimes scours
Irritated animal

32. External Parasites in Horses

33. Flies Horseflies Deer flies Stable flies Horn flies Face flies
Bot flies

34. Horseflies & Deerflies
Breed in boggy areas
Active only during the day in warm weather
Deerflies have patterned wings and are smaller
Horseflies have transparent wings

35. Stable Flies and Horn Flies
Introduced from Europe
Spend almost entire adult lives on their host (horses and cattle)
Stable flies look like house flies
Bite ankles of people, legs of horses

36. Face Flies
Non-biters
Closely resemble house flies, larger than horn flies
Feed on mucous secretions around eyes, nose, mouth
Lay eggs in fresh manure
Can transmit eye problems

37. Bot Flies Lay their eggs on legs and chests of horses
Horses lick that area ingest eggs
Eggs hatch in intestines
Internal/External parasites!
Deworming program to control bots

38. Black Flies/Midges - Onchocerca
Spread a parasitic roundworm, Onchocerca, which causes bumps to form in skin, can also be found in the eye!
Onchocerciasis in the eye of a horse. By permission from Knottenbelt DC, Pascoe RR, Diseases and Disorders of the Horse, Saunders, 2003

39. Ticks
Lyme disease
Rocky Mountain Spotted Fever

40. Lyme Disease
Spirochetal (corkscrew-shaped) bacteria – Borrelia burgdorferi
Transmitted through the bite of a deer or black-legged tick
Endemic areas for Lyme disease:
Northeast
Mid-Atlantic
Northern Midwest states
Northern California

41. Mosquitoes May be encountered day and night Many different species
Attracted to incandescent light but not to fluorescent light!

42. Lice Most common of external parasites Two varieties: Horse with lice:
Chewing/Biting – feed on skin cells
Sucking – feed on blood
Horse with lice:
Heavy dandruff
Greasy skin
Bald spots
Horses can get lice from poultry (so if you have a horse with lice, get rid of the birds) BUT not from cattle and horse lice can’t be transmitted to people

43. Lice Can cause weight loss, general unthriftiness, anemia
Winterspring problem!
Lice are host-specific and spend their entire lives on the animal!
Transmitted by direct contact
Control with pesticide

44. Mites Microscopic! Can cause mange
Sarcoptic mites (head neck, shoulders, flanks, abdomen)
Psoroptic/scab mites – skin surface  gooey scabs and crusts
Chorioptic mites  most common, seen on skin, cause scaling on legs “Clydesdale itch”
Transmission of mites is by contact; horse with mites should be isolated; dispose of infested bedding

45. Horse with psoroptic mange

46. Psoroptic Mange…

47. External Parasites Common to Goats:
Lice - Damalinia
Mites - Chorioptes, Psoroptes, Sarcoptes, Demodex
Flies - Lucilia, Calliphora, Chrysomya
Ked - Melophagus ovinus
Ticks
Nasal bot - Oestrus ovis

48. Lice - Damalinia
Goat lice affect only goats. They may survive on sheep for about 5 to 7 days, but not propagate. Lice from cattle do not affect goats.
Lice spend their whole life on the goat. Individual adult lice survive for about a month.
The spread of lice is by direct contact between goats. Crowded conditions for goats enable rapid spread. At
shows, spread can occur with shared grooming equipment, stalls or trailers.

49. Flies - Lucilia, Calliphora, Chrysomya

50. Flies - Lucilia,
It is responsible for initiating over 90 per cent of all flystrikes. The adult fly is metallic green/bronze in colour. Unlike the native blowflies, Lucilia cuprina breeds mostly on living sheep. Females are attracted to the smell of fleecerot and lay about 250 eggs in clusters in damp fleece. Body length head:abdomen is 9mm.

51. Calliphora
Calliphora stygia - the Eastern Golden Haired Blowfly - is a native brown blowfly that prefers cooler conditions. It occurs in largest numbers in spring and autumn, but may be found on sunny days in winter as well. It disappears during the heat of summer. Although this species mainly breeds in carcasses, it can be troublesome in spring - especially in does with kidding stain. Body length head:abdomen is 13mm.

52. Chrysomya
Chrysomya rufifacies, the green hairy maggot blowfly, is a secondary blowfly species. This means it normally does not strike goats or blow carcasses until primary maggots, like Lucilia or Calliphora, are already feeding. The adult fly is metallic green but can be distinguished from Lucilia by the broad bands on its rounder abdomen and by its black forelegs. The larvae, or "hairy maggots" appear dark and have sharp spines over much of the body. These maggots repel - and will actively feed on - primary maggots in carcasses. By doing this they help control Lucilia and so can be regarded as beneficial flies. However, on goats, they can cause extensive damage not only to the skin but also to the underlying tissue of struck goats. By the time these larvae reach full size on goats the animal has been struck for more than a week - initially by Lucilia, but then by Chrysomya. The very similar, but smaller, Chrysomya varipes fulfils a similar role. C. rufifacies is 9mm from head to abdomen.

53. Ked - Melophagus ovinus
Description: flat, leathery, reddish-brown insect about ¼ inch long; resembles a large tick but has only six legs and is a wingless, bloodsucking fly; a noticeable piercing mouthpart projects forward from the head.
Damage caused: blood loss from keds may cause anemia in young lambs and reduced rate of gain in older lambs; keds and their pupae in wool result in "dirty wool" classification; sheep’s immune response to keds reduces capillary flow in skin resulting in reduced quantity and quality of wool; punctures from feeding cause "cockle" and downgrades hide value.
Method of dispersal or infestation: host-to-host contact facilitated by the sheep’s close herding behavior and at breeding and nursing; keds move in great numbers from shorn adults to lambs; some dispersal between herds is via human handlers and on shearing equipment.
Seasonality: numbers are highest during cool weather, especially on previously uninfested sheep that have not yet developed a protective immune response to keds.

54. Ticks
The American dog tick is also a common pest of pets and humans in Florida. Dogs are the preferred host, although the American dog tick will feed on other warmblooded animals. The nymphal stages of the American dog tick usually only attack rodents.
The Brown dog tick seldom attacks animals other than dogs. It is most likely found where dogs are kept in or around the house. The brown dog tick is not known to transmit diseases to humans but may transmit disease among dogs.

55. One Host Tick

56. Nasal bot - Oestrus ovis
Description: Adult flies are _ to 5/8 inch long, wide-bodied, mottled yellowish to gray-brown, and quite hairy; mouthparts are rudimentary. Larvae are grublike maggots that reach one to one and one-fourth inch in length.
Domestic animals affected: sheep, goats.
Damaged caused: extreme annoyance during larviposition; later, during larval development, a snotty and sometimes bloody nasal discharge, loss of appetite, vigorous head shaking, secondary infection of the sinuses; sometimes death.
Development: complete metamorphosis: egg (hatches within female), larval stages, pupa, adult fly.
Generational time: typically one year, but spring larviposition may result in a complete developmental cycle that produces adults within 10 to 12 weeks.

57. QUESTIONS?