Exam 2: Large Animal Ectoparasites

generally describe the New World Screwworm

• obligatory myiasis

• ID by dark tracheal tubes and characteristic spiracles 

• gravid females deposit >200eggs in open wounds and are aggressive in seeking them out, animals will die if left untreated

• REPORTABLE

new world screwworm eradication

• use of sterile insect technology

• gamma radiation makes sterile males that are released on mass, mate with females and ends their mating life

  • be on the look out and report any suspected cases 

prevention of myiasis in LA 

• remove carcasses and rotting food waste

• treat or remove manure

• wound care for navels of newborns, cuts, peeling brands, fly and tick bites

• in sheep, complete shearing or shearing in areas typically affected by fly strike such as the urine soaked areas between the legs and around tail and prepuce, head

• prevention through high pressure spraying of rear ends

• permethrin

generally describe Hypoderma spp flies

• botflies

• also called heel flies, gadflies, warble flies

• warbles = swellings, grubs = larvae within the warbles

• hypoderma lineatum and hypoderma bovis

treatment of hypoderma spp

• treatment given too late in the fall may cause bloat for lineatum or ataxia/posterior paralysis for bovis

• treat with ivermectin, doramectin or moxidectin (ML) immediately after adult fly activity ceases for the season

Oestrus ovis- sheep nasal botflies 

• female flies deposit larvae in or around nostrils, pupae in soil 

• heavy infections cause nasal discharge, secondary bacterial infections usually occur 

• may lower weight gains and wool production 

treat Oestrus ovis

ivermectin

prevent biting midges

• eliminate breeding sites where possible

• stable horses during peak activity dusk and dawn

• repellants on horses

  • fans in stables

prevent blackflies 

• stable horses during peak activity (daylight, still air)

• horses repellants, cattle pour ons 

• horses fly masks with ear guards, petrolium inner surface of ear 

prevent mosquitoes

• remove water sources, stock permanet water sources with minnows

• stable horses during peak activity first 2hrs after sunset

• horses repellants, cattle residual insetcicides

• residual insecticides on resting sites

• fans in stables

prevent tabanids

• locate pastures away from wooded areas

• stable horses during day

• repellants on horses

prevent house and face flies 

• eliminate breeding sites 

• spray breeding areas

• stable horses during warm sunny weather 

• horse= whole body sprays, cattle= whole body dusts, sprays or backrubbers, insecticide impregnated ear tags, space sprays 

• insecticidal resin strips, fly baits 

  • horses= fly face masks, parasitoid wasps, cattle= feed through insecticides 

prevent stable flies

• eliminate breeding sites

• horses= repellants, cattle= whole body dusts, sprays or backrubbers

• residual insecticides on resting sites

• feed through insecticides

prevent horn flies

• eliminate breeding sites where possible

• cattle = dusts, sprays, backrubber, insecticide impregnated ear tags, bruce walk through horn fly traps

describe Melophagus ovinus sheep ked 

• large palps, piercing mouthparts retracted when not feeding 

• blood feeding 

• larviparous, larva pupates rapidly and adults are permanent ectoparasites 

• blood sucking may lead to loss of condition and anemia, itch causes wool loss 

treatment/prevention of keds

• shearing

  • insecticidal dips or sprays

Linognathus vituli and Bovicola bovis lice

• cattle

• skin of head around eyes (v), neck, flanks and tail base (B)

• spread by contact, burdens are highest in late winter and early spring

• intense irritation damages hides, reduced productivity, diminished healthy

• treat woth MLs given SQ or pour over

• control with good nutrition

Haematopinus asini and Bovicola equi lice 

• horse 

• skin of head, neck, back, brisket, between legs (A), skin of neck, flanks and tail base (E)

• spread by contact, burdens highest winter and early spring 

• intense irritation causes matting and hair loss (A also anemia)

• pyrethroid based pour on insecticides 

• control= scald grooming equipment, wash blankets and rugs, clean saddlery 

factors affecting the habitat of ticks

• humidity, temperature, soil moisture

• dense vegetation , dense shade, host interaction

how to manage ticks generally

• must know biology and seasonal habits

• apply treatments during spring and summer when adults are most active

• habit modification such as brush removal, stocking chickens, fire ants

• dips most effective, also sprays, slow release implants, pir ons, spot ons

• strict adherence to federal regulations

• drug resistance to ticks, MLs

Dermacentor variablilis 

• cattle 

• major vector for R. rickettsii, F. tularemia and anaplasma spp, may cause tick paralysis in dogs and humans 

• Coumaphos and dichlorvos as sprays or backrubbers, impregnated ear tags. 

• not all products safe for dairy cattle 

Dermacentor andersoni

• cattle

• major vessel for R. rickettsii, Anaplasma, tick paralysis

• coumaphos and dichlorvos as sprays or back rubbers

• impregnated ear tags

  • not all products safe for dairy cattle

Amblyomma americanum tick

• deep, painful bite wounds that may become infested or infected, transmit E. chaffeensis and E. weingi, F. tularensis, tick paralysis

• Coumaphos and dichlorvos as sprays or backrubbers

• ear tags

• wound care

• not all products for dairy cattle

Rhipicephalis annulatus tck 

• cattle

• vector for Babesia bigemina, eradicated from US through dipping cattle

• permanet quarantine zone with surveullance program at US Mexico border 

  • dipping with Coumaphos 

Otobius megnini ticks

• cattle and horses

• larvae and nymph in the ear, adults do not feed but lay eggs in environment

• one host tick

• otitos externa

• pyrethroid insecticides in horses, acaricide impregnated ear tags, insecticidal dusts or emulsion concentrates instilled into the ear canal in cattle

Dermacentor albipiictus tick

• horses, skin

• one host tick- larvae, nymphs and adults all on single hosts

• heavy infestations can occur in long wiinter coats, debilitation and anemia possible, causes heavy losses among moose

• pyrethroid based insecticides, eliminate understory vegetation

Chorioptes bovis 

• mite 

• tail and legs, escutcheon n cows 

• contagious 

• crusty lesions with thickened skin causig irritation and restlessness

• MLs, isolate affected horses, sterilize water buckets, curry combes, brushes, ect, leave stalls vacant for 2-3 weeks 

Psoroptes ovis mite

• non-burrowing, feed on skin cells bacteria and lymph

• transmission by physical contact, survive in environment for >18d

• severe itch, exudation, scale and crust formation, excoriation, wool loss, weight loss, sheep may die

• rapid spread

• plunch dipping with head immersion, injectiable ivermectin