Ectoparasites

Sarcoptes (Scabies)

Common in dogs (elbows and ear flaps) and pigs (external ear canals). Spread by foxes. Separate spp. in cats and in guinea pigs (rare). Zoonotic. Adult females burrow in epidermis causing hypersensitivity, very itchy. 2-3 week survival off host.

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Knemidokoptes

'Bird scabies'. Live in scales on legs/feet, scales thicken and are itchy. Not very common but spreads quickly within a colony.

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Psoroptes

Sheep scab. Long pretarsus. wool loss. Can survive in environment for up to 18 days (infective source in environment). When treating be careful of shared ground (eg. fence posts) and treat whole flock. Also rabbit spp. and ear spp. in livestock.

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Chorioptes

Common in cattle and horses (NOT pets). Pasterns rubbed sore (also found on base of tail perineum and udder). 3 weeks survival off host.

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Otodectes

ONLY in pets (dogs, cats, carnivores). Not very common- normally only in young and welfare cases. Found deep in the ear canal. Very motile, causes accumulation of ear wax.

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Demodex

Lives in hair follicles deep in dermis, only causes disease in immune compromised. Highly host specific, cannot live off host and does not transfer between hosts except when suckling (except cats). Hair loss, skin goes grey then black, smell, crusty

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Cheyletiellidae

Infects rabbits, dogs, cats. Zoonotic. Not very common due to flea treatments. Transfer easily between hosts, v. motile, 'walking dandruff'. Survive up to 10 days off host.

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Neotrombicula

Berry bugs/harvest mites. Only larvae that causes skin disease in animals (6 legs!). Seen as orange spots on skin (accumulations). Hypersensitivity and pruritis. No direct transfer- infection from being in same area as pets.

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Mesostigmatid (gamesid) mites- red mite

Poultry. V. tough, survive without food for months. Ingest blood (nymph and adult). Generally found in environment not on host (feed at night). Short life cycle (7 days). 34 weeks survival off host- hygiene between batches important!

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Mesostigmatid (gamesid) mites- northern fowl mite

Poultry. Entire life cycle on host. Short life cycle (5-12 days), only 1-3 weeks survival off host (easier to kill off than rm). Quite rare compared to rm. As with rm: irritant, anaemia, death. Transmits Salmonella, Mycoplasma, Avipox virus.

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Give 3 orders of insect

lice, fleas, flies

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Describe the differences in appearance between Psoroptes and Chorioptes

Psoroptes: funnel shaped suckers, 3-jointed pedicel, pointed mouthparts, rounded male mating parts. Chorioptes: 'wine glass suckers', short unjointed pedicels, rounded mouthparts, square ended male mating parts.

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What organ is used during tick questing?

Haller's organ, chemical olfaction helps sense host.

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Gasterophilus spp.

Eggs on horse's legs, horse ingests eggs, larvae found in horse's stomach. Detach and are excreted in faeces. Probably dosen't cause disease and are sensitive to wormers.

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Lucilia sericata

Blowfly strike. Fast development- inspect sheep every day. Careful of faeces around the perineum. Warmth/wet increase likelihood. Common in sheep and rabbits. Rabbits: dental issues decrease grooming, high starch diet=diarrhoea.

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Tebanidae

Horse fly (also bite other species). Painful bites, cause allergic reaction. Strong fliers.

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Musca autumnalis

Face fly (non-biting). Feed on secretions of the eyes, nose and mouth in cattle and sheep. Transmit bacterial infections eg. infectious Bovine keratoconjunctivitis (new forest eye). Difficult to control.

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Culicoides

Biting midges. Cause of sweet itch (hypersensitivity, crusting around tail/mane). Aquatic larva- keep horses away from ponds etc. Larva overwinter. Weak fliers but can be blown long distances by the wind (Schmallenburg, bluetongue from the continent)

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Dermacentor reticulatus

Marsh tick. Reticulated pattern on back, crenulations around back. 3 host tick. preferred hosts: dog, cat, wildlife. Exotic- uncommon in UK. Transmits Babesia Canis.

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Rhipicephalus sanguineus

Brown dog tick/kennel tick. Exotic. Transmits protozoal pathogens inc. Babesia Canis. Lives inside house/kennel, prefers: warmth, low humidity. life cycle completed in 3 months, can diapause for a year in cold.

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Ixodes ricinus

Sheep/deer tick. 3 host tick. Most common UK tick in livestock and pets. Active from 6oC but optimum at 17- 20oC (spring). Found in rough land, v. tough, can survive in environment for months.

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What are the main features of insects?

Segmented body: head, thorax, abdomen. 3 pairs of jointed legs. Tough exoskeleton for protection (epidermis, 3 x cuticle, waxy waterproof layer). Seta (hairs) allow sensation from outside. Breath via spiracles/stigmata.

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What are the main features of mites?

Body, legs (both=idiosoma), mouthparts (gnathosoma). 4 pairs of legs (except larvae which have 3 pairs).

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Describe the pathology of ticks

blood loss (anaemia if many present), Inflammation (salivary antigens), skin lesions, lower productivity (if many), unhappy, tick paralysis (exotics- salivary toxins,neurological issues), disease vectors

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Ectoparasites

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