ectoparasites sheep

Species

·    Psoroptes ovis (sheep scab)

o  Itching/scratching, biting at flanks, restlessness, loss of wool, exudative

·    Chorioptes ovis (chorioptic mange)

·    Demodex ovis (demodectic mange)

·    Sarcoptes scabei var ovis (sarcoptic mange)

Sheep scab/scabies

Impacts:

·    Itching, scratching, biting at flanks

·    Loss of wool

·    Exudative and pruritic skin lesions

·    Skin covered in scabs, skin excoriations

·    Secondary skin infections, severe pain

·    Weight loss

Diagnosis:

·    Skin scrape – oval shaped mites with funnel suckers

·    Blood sample for ELISA – identify antigens in subclinical carriers

Treatment:

·    OP dip

·    ML injection – moxidectin (but resistance), doramectin

Control issues:

·    Safety of chemical control measures (e.g. OP dips)

·    Resistance of mites to MLs

·    Sub-clinical infestation – spread disease without showing clinical signs

·    Biosecurity issues

Prevention:

·    Quarantine new animals

·    Serology – high sens and spec

Species

Sucking:

·    Linognathus vituli

·    Pedalis

Biting:

·    Bovicula ovis

Lifecycle

·    Simple and direct – all on host

Impacts

·    Itching, rubbing, licking

·    High burden of sucking = anaemia

·    Decreased BCS/DLWG

·    Damaged skin/fleeces

Diagnosis

·    See with naked eye

·        Usually affect animals that have something else going on – consider underlying diseases

Treatment

·    Pour on synthetic pyrethroid – deltamethrin

·    OP dips – PPE required

Most common species

·    Ixodes ricinus – 3 host life cycle

Impacts

As vectors for disease:

·    Louping ill – weaned lambs/yearlings

o  Encephalomyelitis ® death, seizures, paralysis (zoonotic)

·    Tickborne fever – immunosuppressive disease

o  Pyrexia, anorexia, depression, abortion

·    Tick pyaemia – staphylococcal infection following immunosuppression

o  Lameness, paralysis and death in lambs

Species

·    Lucilla sericata most common

Myiasis

Clinical signs:

·    Separation from flock, restlessness

·    Pruritus

·    Discoloured wool, unpleasant smell

Treatment:

·    Synthetic pyrethroids

·    Shear and clean affected areas

·    NSAIDs for pain relief

Prevention:

·    Reduce sheep susceptibility

o  Mechanical control measures – dagging, shearing

o  Chemical control measures – OP dips, synthetic pyrethroids (prevention + tx, pre-shearing), IGRs (prevention only, post-shearing)

o  Reduce faecal soiling

o  Monitor open wounds

·    Reduce fly abundance