Sheep lice and keds

Question 1

What are the symptoms of Psoroptes ovis? Which species does it affect?

Answer 1

Intense itching, rubbing, scratch, nibbling

Sheep - rarely cattle and horses

Question 2

What are the distinguishing features of Psoroptes ovis?

Answer 2

Pointed mouth 
Long setae (hair like strucutres)
Long legs
Jointed pedicles with 3 part trumpet 
Thumb print pattern on dorsum (all mange mites)

Question 3

How long do Psoroptes mites live for? How many eggs do they lay? How long is their life cycle?

Answer 3

1 month
100
16 days

Question 4

Are Psoroptes burrowing or non-burrowing?

Answer 4

Non-burrowing - feed at surface of skin

Question 5

What are all mange mites sensitive to? What type of fleece does this mean they struggle to survive on?

Answer 5

Sensitive to desiccation

Struggle to survive on longer fleece

Question 6

What are Psoroptes lesions like? Where are the mites found?

Answer 6

Inflammation, serous exudate, scale and crust. Centre is thick and crusty, vesicle ruptures to form moist yellow pustule
Mites found on moist skin at edge of resin

Question 7

Psoroptes lesions spread rapidly and cover most of the body in weeks. What does this cause?

Answer 7

Chronic exudative superficialities dermatitis

Question 8

Describe the pathogenesis of psoroptes ovis?

Answer 8

Type I hypersensitivity due to antigens in mite faeces
Causes chronic skin changes, hyperkeratosis, aural haematomas, intense irritation, decreased weight gain, seizures, death

Question 9

How is psoroptes ovis diagnosed?

Answer 9

Clinical signs, skin scraping

Question 10

What is sheep scab also known as? What is it caused by?

Answer 10

Psoroptic mange

Psoroptes ovis

Question 11

What are the symptoms of sheep scab?

Answer 11

Pruritic, irritation 
Scratching against walls
Wool loss
Weight loss
Stood alone 
Depressed
Wool in mouth

Question 12

What can be used to test for Sheep scab?

Answer 12

Nibble reflex - sheep respond to back scratching with lip and tongue movements

Question 13

How is sheep scab transmitted?

Answer 13

Direct contact, contaminated environment, fomites

Question 14

How long do Psoropes ovis survive off the host?

Answer 14

2 weeks

Question 15

What introduces sheep scab to a flock?

Answer 15

Poor fencing, mixing flocks, contaminated lorries

Question 16

What season is Sheep Scab usually seen?

Answer 16

Autumn/Winter

Shearing in Summer reduces population

Question 17

Where are the sites of mites on sheep, that act of reservoirs?

Answer 17

Axilla (armpit)
Ears
Skin folds

Question 18

What is the treatment for Sheep scab?

Answer 18

OPs - dip in Diazinon

Injectable MLs - ivermectin

Question 19

What species of Psoroptes is found in rabbits? Where is it usually localised and what does it cause?

Answer 19

Psoropotes cunicoli

Ears - causes mange in auditory canal

Question 20

Where about on sheep do Chorioptes bovis usually affect?

Answer 20

Lower limbs, abdomen

Question 21

What are the 3 species of lice found in sheep? Which is biting and which is sucking?

Answer 21

Damalinia ovis (body louse)
Linognathus pedalis (foot louse)
Linognathus ovillus (face louse)

Question 22

What are the symptoms of lice in sheep?

Answer 22

Restlessness, rubbing, stopping feeding, wool loss if heavy infestation

Question 23

What do lice lesions attract?

Answer 23

Blowflies

Question 24

How are lice controlled in sheep?

Answer 24

Shearing
Quarantine
Remove wool rom housing

Question 25

What is the weird looking half tick half lice? What species is this?

Answer 25

Sheep keds

Melophagus ovinus

Question 26

What is the morphology of sheep keds?

Answer 26

Flattened like lice
Short legs with stout claws
5mm
True flies but no wings

Question 27

Where do larvae of Melophagus ovinus develop?

Answer 27

Inside female
Become pupa in wool
Emerge 2-5 weeks later

Question 28

How are sheep keds transmitted? What do they cause?

Answer 28

Direct contact

Pruritis, loss of condition

Question 29

What season are sheep keds usually present? Do they transmit pathogens?

Answer 29

Winter

Transmit non-pathogenic Trypanosoma melphagium