PARASITOLOGY - Ectoparasites Flashcards
Why are ectoparasites typically more prevalent in housed ruminants?
Increased contact between animals
Longer hair coats
Housing provides ideal environment for ectoparasites
What are the two most common lice seen in cattle?
Bovicola bovis (chewing louse)
Linognathus vituli (sucking louse)
What is the distinctive morphological feature of bovicola bovis?
Bovicola bovis has a round head
Where on the body is bovicola bovis typically found?
Bovicola bovis is typically found on the withers, shoulders and dorsum of cattle
What are the clinical signs of bovicola bovis?
Pruritis
Hair loss
Lick marks
Lice eggs on hair shafts
Adult lice visible
What can also cause hair loss around the neck and shoulders in housed cattle?
Housed cattle can also have hair loss as a result of feed barriers, however, this will not be accompanied by pruritis
What is the distinctive morphological feature of linognathus vituli?
Linognathus vituli has a distinct long, pointed head
Where on the body is linognathus vituli typically found?
Linognathus vituli is typically found on the head, face and neck (as it is a blood feeder)
What are the clinical signs of linognathus vituli?
Dark lice (as its a blood feeder) on the neck, head and around the eyes
Anaemia (rare and only in severe cases0
How do you diagnose lice in cattle?
Assess clinical signs
Tape samples and microscope assessment
What is the most common mite seen in cattle?
Chorioptes bovis (chewing mite)
Where on the body is chorioptes bovis?
Chorioptes bovis causes tail head and heel bulb mange
What are the clinical signs of chorioptes bovis in cattle?
Pruritis
Hair loss
Self-trauma
Foot stamping
What are the less common mites seen in cattle?
Sarcoptes scabiei (burrowing mite)
Psoroptes ovis (sucking mite)
What are the clinical signs of sarcoptes scabiei?
Pruritis
Thick crusts
Hyperkeratosis
Self-trauma
Which cattle breeds are at an increased of psoroptes ovis?
Belgian Blue
Charollais
Due to their light coloured skin
What are the clinical signs of psoroptes ovis in cattle?
Moist, exudatory, inflammatory, expanding dermatitis
Pruritis
Where are psoroptes ovis mites found?
Psoroptes ovis mites are found at the periphery of the lesions (keep this in mind when doing skin scrapes)
What is the distinctive morphological feature of psoroptes ovis?
Psoroptes ovis have thin tubercles at the end of their legs
How do you diagnose mites in cattle?
Assess clinical signs
Skin scrapes and microscope assessment
What are the consequences of ectoparasites in cattle?
Welfare issue
Decreased productivity
Production losses
Poor growth rates
Decreased body condition score
Hide damage
Treatment costs
If cattle are itching, won’t be eating, ruminating etc.
How do you treat lice and mites in cattle?
Treat all animals with synthetic pyrethroids or macrocyclic lactones and keep treated animals seperate from untreated animals
But make sure to check the data sheet to ensure the drug, formulation and route of administration you’re using will work for the mite or louse you have identified. Also check withdrawal period!
What are the two most common lice seen in sheep?
Bovicola ovis (chewing louse)
Linognathus vituli (sucking louse)
How do you treat lice in sheep?
Treat all animals with synthetic pyrethroids or organophosphate dips and keep treated animals seperate from untreated animals
But make sure to check the data sheet to ensure the drug, formulation and route of administration you’re using will work for the louse you have identified. Also check withdrawal period!
What is the most significant ectoparasite in sheep?
Psoroptes ovis
Which disease is caused by psorptes ovis in sheep?
Sheep scab
(T/F) Sheep scab is a notifiable disease in the UK
TRUE.
Describe the pathogenesis of sheep scab
Antigens in the faeces of Psoroptes ovis mites causes a type I hypersensitivity reaction, stimulating skin inflammation and serous exudate secretion. This serous exudate dries to form a scab with a moist border and inflamed skin. Psoroptes mites are active at the border of the scab and as the mite population increases, the scab will extend. These scabs cause pruritus causing the host to rub and bite leading to hair loss and skin excoriation
What are the clinical signs of sheep scab?
Moist, exudatory, inflammatory, expanding dermatitis
Pruritis
Wet, discoloured wool
Wool loss
Self-trauma
Loss of body condition
How should sheep scab be diagnosed?
Part the wool of the sheep and look for scab lesions. Take a skin scraping at the edge of the lesion in order to confirm that the species of mite present is Psoroptes ovis under the microscope
What increases risk of direct transmission of sheep scab?
Shows
Market
Brought in animals
Boundaries with neighbouring flocks
Shared grazing
What increases risk of indirect transmission of sheep scab?
Shearing equipement (if the blades aren’t cleaned properly)
Transport (if lorry hasn’t been cleaned properly)
On fences
At markets
What can be done to control sheep scab?
Ectoparasiticides
Movement control
Biosecurity
Which ectoparasiticides can be used to control sheep scab?
Organophosphate (OP) dips
Injectable macrocyclic lactones
Organophosphate (OP) dips are the gold standard
What are the advantages of organophosphate (OP) dips for controlling sheep scab?
No reported resistance of psoroptes ovis to organophosphates
Has a prolonged effect
Can wash off the antigens and improve clinical signs
Can add dye to the dip to know which sheep have been treated and which haven’t
What are the disadvantages of organophosphate (OP) dips for controlling sheep scab?
Labour intensive
Require certificate of confidence and SEPA license to use organophosphates
Why do farmers require a certificate of confidence and SEPA licence before using organophosphate dips?
Organophosphates can be toxic to humans and animals and can persist in the environment if disposed of incorrectly
What are the advantages of injectable macrocyclic lactones for controlling sheep scab?
Less labour intensive
Does not require certificates and licenses for use
Less stressful, especially for pregnant ewes
More convenient for quarantine treatment
What are the disadvantages of injectable macrocyclic lactones for controlling sheep scab?
Reported resistance of psoroptes ovis to macrocyclic lactones, and overuse of injectable macrocyclic lactones for both sheep scab and worm control can lead to the development of resistance in both psoroptes ovis mites and gastrointestinal nematodes
How do you treat sheep scab?
Treat all animals with organophosphate (OP) dips or injectable macrocyclic lactones and keep treated animals seperate from untreated animals
But make sure to check the data sheet to ensure the drug, formulation and route of administration you’re using will work for the louse you have identified. Also check withdrawal period!
What are the consequences of sheep scab?
Welfare issue
Decreased productivity
Production losses
Poor growth rates
Decreased body condition score
Hide damage
Wool loss
Treatment costs
Why is summer shearing so important for sheep?
Summer shearing removes lice, sheep ked and is helpful to reduce the risk of fly strike
When is fly strike most prevalent?
Fly strike is most prevelant during the summer
What are the risk factors for fly strike in sheep?
Diarrhoea
Late summer shearing
Wet wool
How can you control fly strike in sheep?
Ectoparasiticides
Summer shearing
Carcass disposal
Tail docking
Prevent and treat diarrhoea
Which ectoparasiticides can be used to control and treat fly strike?
Synthetic pyrethroids
Insect growth regulators (IGR)
Organophosphate (OP) dips (consider the degree of severity of the lesions before dipping them)
But make sure to check the data sheet to ensure the drug, formulation and route of administration you’re using will work for the mite or louse you have identified. Also check withdrawal period!
Which vector borne diseases transmitted by ticks are most significant in cattle?
Babesiosis (red water fever)
Which vector borne diseases transmitted by ticks are most significant in sheep?
Anaplasma (tick borne fever)
Flavivirus (louping ill)
Tick pyaemia (secondary infection of tick bite lesions by staphylococcus)
When is tick control indicated?
Tick control is indicated if you diagnose tick-borne diseases on the farm
Which ectoparasiticides can be used to control ticks?
Synthetic pyrethroids
Organophosphate (OP) dipsn
But make sure to check the data sheet to ensure the drug, formulation and route of administration you’re using will work for the mite or louse you have identified. Also check withdrawal period!
Which vector borne diseases can be transmitted by culicoides (midges)?
Blue tongue
Schmallenburg virus
Which disease can be spread by face flies?
Pink eye
