Flashcards in Sheep lice and keds Deck (29)
What are the symptoms of Psoroptes ovis? Which species does it affect?
Intense itching, rubbing, scratch, nibbling
Sheep - rarely cattle and horses
What are the distinguishing features of Psoroptes ovis?
Long setae (hair like strucutres)
Jointed pedicles with 3 part trumpet
Thumb print pattern on dorsum (all mange mites)
How long do Psoroptes mites live for? How many eggs do they lay? How long is their life cycle?
Are Psoroptes burrowing or non-burrowing?
Non-burrowing - feed at surface of skin
What are all mange mites sensitive to? What type of fleece does this mean they struggle to survive on?
Sensitive to desiccation
Struggle to survive on longer fleece
What are Psoroptes lesions like? Where are the mites found?
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
Psoroptes lesions spread rapidly and cover most of the body in weeks. What does this cause?
Chronic exudative superficialities dermatitis
Describe the pathogenesis of psoroptes ovis?
Type I hypersensitivity due to antigens in mite faeces
Causes chronic skin changes, hyperkeratosis, aural haematomas, intense irritation, decreased weight gain, seizures, death
How is psoroptes ovis diagnosed?
Clinical signs, skin scraping
What is sheep scab also known as? What is it caused by?
What are the symptoms of sheep scab?
Scratching against walls
Wool in mouth
What can be used to test for Sheep scab?
Nibble reflex - sheep respond to back scratching with lip and tongue movements
How is sheep scab transmitted?
Direct contact, contaminated environment, fomites
How long do Psoropes ovis survive off the host?
What introduces sheep scab to a flock?
Poor fencing, mixing flocks, contaminated lorries
What season is Sheep Scab usually seen?
Shearing in Summer reduces population
Where are the sites of mites on sheep, that act of reservoirs?
What is the treatment for Sheep scab?
OPs - dip in Diazinon
Injectable MLs - ivermectin
What species of Psoroptes is found in rabbits? Where is it usually localised and what does it cause?
Ears - causes mange in auditory canal
Where about on sheep do Chorioptes bovis usually affect?
Lower limbs, abdomen
What are the 3 species of lice found in sheep? Which is biting and which is sucking?
Damalinia ovis (body louse)
Linognathus pedals (foot louse)
Linognathus ovillus (face louse)
What are the symptoms of lice in sheep?
Restlessness, rubbing, stopping feeding, wool loss if heavy infestation
What do lice lesions attract?
How are lice controlled in sheep?
Remove wool rom housing
What is the weird looking half tick half lice? What species is this?
What is the morphology of sheep keds?
Flattened like lice
Short legs with stout claws
True flies but no wings
Where do larvae of Melophagus ovinus develop?
Become pupa in wool
Emerge 2-5 weeks later
How are sheep keds transmitted? What do they cause?
Pruritis, loss of condition