Parasitic skin disease of farm animals Flashcards
Important common parasites of sheep?
- Psoropties ovis (sheep scab mite) – Severe and contagious
- Myiasis (blowfly strike) – massive welfare concern
- Lice – Less severe than sheep scab but associated with debility and weight loss
- Ticks – vector for Louping ill, S.aureus, TBF
- Head Flies – important for horned sheep
- Keds – uncommon and not a big issue
- Nasal Bots – uncommon, unpleasant when they do occu
Important common parasites of cattle?
- Lice – 4 species of louse – (1 biting, 3 sucking)
- Mites – chorioptes mainly on tail head, self-limiting, also occasional rare cases of sarcoptic or psoraoptic mange which are more severe
- Ticks – Vector for TBF and Babesia
- Flies – vector for Morexella bovis and Summer mastitis pathogens
- Warble Fly – Notifiable in Scotland (no uk outbreaks since 1990,
- Worms – Onchocerca – not a big issue clinically
Name the biting and sucking lice?
What is cattle lice treatment?
- Pour-on synthetic pyrethroid preparation such as deltamethrin. Kills everything
- Pour-on group 3-ML anthelmintics (ivermectin, doramectin and eprinomectin). Kills everything
- Injectable group 3-ML anthelmintics (ivermectin, doramectin and eprinomectin) will remove all sucking lice and >98% of biting lice.
- All cattle in direct contact must be treated. Treat at start of winter housing period.
What is sheep lice treatment?
- Pour-on synthetic pyrethroid preparation such as deltamethrin or cypramethrin. Kills biting lice
- Organo-phosphate dips (not sprays or jet systems) kills everything including humans so be very careful that correct PPE and protocols are used
- All sheep in direct contact must be treated. Treat at start of winter housing period
- NB: unlike cattle injectable ML wormers are not effective against biting sheep lice
- No injectable suitable for sheep lice treatment
What is this?
Pinkeye disease
Infectious Bovine Keratoconjunctivitis (IBK) aka newforest disease
- Agent: the bacterium Moraxella bovis
- Vector: Face fly
- Disease: 4 stages
-
Signs: corneal ulcers,
- oedema, lacrimation, opacity
- epiphora
- Treatment: Antibiotics
- (Routes; IM, SC, topical, subconjunctival)
- Prevention: Fly control with topical SP eg
Permethrin
What is this?
Blowfly strike (ovine cutaneous myiasis)
- Agent: blowflies (Lucilia spp., Calliphora spp., Phormia spp.)
-
Risk factors:
- Climatic conditions (warm & wet ),
- breed susceptibility – heavy dense fleece
- Wet or dirty fleece – easy for larvae
- Treatment:
- Insecticides (SP’s and OP’s)
- Prevention long acting SP’s (synthetic pyrethroids) and Insect Growth Regulators (IGR’s – no good for treatment only prevention)
- Non-chemical prevention - genetic selection (wool shedding breeds), early shearing, dagging and good endoparasite control
What is the impact of warble fly?
- Gadding behaviour: Flies cause harassment to cattle, which become (1) restless leading to physical injuries and (2) depressed, leading to decreased production and growth
- Ectopic migration & Paralysis: caused esp. by wrong treatments
- Damage caused by warbles
- Downgrade of the hide caused by perforations of skin by breathing larvae
- Reduced reproduction: caused by large number of warbles under skin in spring
How should warble fly be managed?
Treatment:
- OPs - 98% effective in autumn and less efficient in spring
Control:
- In 1978 – Legislation was introduced to dress all obvious warble-infested cattle in spring
- First 5 years of eradication, the incidence reduced from 34% to 0.02%
- Since 1990 no living larvae have been found on British Cattle.
- Have been eradicated, but still notifiable
- All imported cattle must be treated on arrival
Outline surface and burrowing mites?
Where are characteristic locations of chorioptic mange?
Chorioptic Mange (tail mange, leg mange, scrotal mange)
What is seen here?
Sheep scab
Psopties. Ovis
- Notifiable in Scotland
- Legal requirement to treat or slaughter in all parts of the UK
- Oval-shaped mites identified by their three-segmented pedicels and funnel-shaped suckers.
How is sheep scab treated?
(Organo-Phasphate plunge dipping)
- diazinon
- difficult to perform compare to injections
- NB: Moxidectin resistance now reported in P.ovis (big problem means roundworms are now not sensitive)
ML (macrocyclic lactone) injections
- One injection of doramectin or moxidectin afford minimum 17 to 28 days residual protection
- adds the constraint of having to move the treated sheep onto scab-free pasture immediately after treatment, because of the time it takes (~10 days) after endectocide treatment before all P. ovis mites are killed
What is the life cycle of ixodes ricinus tick?
Name two main types of livestock tick?
Discuss which ticks act as vehicles for disease-causing agents?
Give some d/dx for this lesion description
Lesion description
Alopecia (fleece loss)
Dirty fleece due to scratching
Erythema & hyperaemic skin
Serous exudation & crusting
Excoriation due to self inflicted trauma
NB Lesions usually start at the shoulder and move caudally & ventrally. The skin at the centre of the lesion becomes keratinised with thickened corrugations.
Draining lymph nodes are enlarged (esp pre-scapular or pre-femoral)
