sheep derm Flashcards
what is the most important sheep ectopatrasite?
psoroptes ovis - sheep scab, sever and contagious
what are the mites that affect sheep?
◦ sheep scab (Psoroptes ovis) (which can be severe and contagious,) - most important for sheep
◦ chorioptic mange (Chorioptes ovis),
◦ demodectic mange (Demodex ovis)
◦ sarcoptic mange (Sarcoptes scabei var. ovis).
what flys are responsible for blowfly strike of sheep?
initiated by the greenbottle fly (Lucilia sericata).
odour from the first strike attracts Phormia terraenovae (blackbottle flies) and Calliphora erythrocephala (bluebottle flies).
what is the blowfly strike lifecycle?
◦ Each female lays up to 250 eggs that hatch after about 12 hours.
◦ After three days the mature larvae drop off the sheep and pupate in the soil.
◦ Blowfly strikes usually occur in waves. The first fly lays her eggs and the odour from this strike attracts other flies Phormia terraenovae (blackbottle flies) and Calliphora erythrocephala (bluebottle flies).
◦ They lay eggs in these areas, which hatch within 12 hours, and maggots feed on the tissue for 3 to 10 days, before dropping off to become mature flies.
* The entire life cycle from egg to adult can occur in less than 10 days in optimal conditions.
what are the signs of blowfly strike?
first signs: patch of discoloured wool and agitation.
then: separation from the flock, pruritus, restlessness, discoloration of the wool and unpleasant smell.
what is the treatment of blowfly strike?
- application of insecticides (usually synthetic pyrethroids, although organophosphate dips are also licensed for treatment) coupled with shearing and cleaning of the affected areas.
- Topical antibiotics may be used, along with systemic antibiotics in severe cases.
- NSAIDs can also be given for pain relief. (off licence)
- The rest of the flock should be closely monitored for any signs of strike.
what is the prevention of blowfly strike?
- Mechanical control measures, such as dagging, shearing or tail docking.
- Chemical control measures, such as organophosphate dips, synthetic pyrethroids or insect growth regulators.
- Reducing faecal soiling (for example by ensuring nematode control) and close monitoring of any open wounds.
- Selecting breeds with an open fleece and avoiding excessive skin folds around the breech or vulva may also help in some systems.
what are the Species of lice that affect sheep?
Sucking lice:
* Haematopinus spp.
* Linognathus spp.
Biting lice:
* Damalinia (Bovicola) spp - more common in sheep
- Biting louse is **Bovicola ovis **– it can only survive off the host for a very short period of time so spread is by direct contact. Lice like dry and cold conditions, they are killed by heat and wet conditions – pediculosis is a disease of housing when it is cold and fleece is long.
what is the treatment of lic ein sheep?
1.** Pour-on synthetic pyrethroid preparation such as deltamethrin or cypermethrin. Kills biting lice **
2. Organo-phosphate dips (not sprays or jet systems) kills everything but can cause harm to people too so be very careful that correct PPE and protocols are used
what three diseases are ticks the vectors of in sheep?
- Louping ill – mortality rate may be up to 60% in naïve flocks, 5-10% in endemic areas.
- Tickborne fever – can also affect cattle
- Tick pyaemia – a ddx for joint ill in sheep (not seen in cattle). Tick isn’t a direct vector for the bacteria but the bite allows the bacteria to enter the blood stream.
what does louping ill cause in sheep, what age of sheep does it affec the most, what is the control?
- Viral infection (RNA Flavivirus) causing encephalomyelitis resulting in death, seizures, paralysis and death.
- Most common in weaned lambs and yearlings (lambs get passive protection in colostrum).
- Mainly affects sheep and grouse, but can cause disease in other animals and is zoonotic
- Control is mainly through tick control, although vaccination can play a role (but not currently available)
what bacteria causes tickborne fever in sheep? what are the signs/what does it cause? what age of sheep is affected the lease?
- Immunosuppressive disease caused by bacteria Anaplasma phagocytophilum. Bacteria infects and destroys WBC causing leucopaenia.
- Affected animals are pyrexic, anorexic and depressed. Pregnant ewes may abort and naïve rams may become infertile.
- Lambs born in endemic areas are infected within the first 2 weeks of life and have mild symptoms. Naïve animals introduced to endemic areas show more severe signs.
what bacteria is responsible for tick pyaemia?, what age animals are normally affected, what are the signs of this?
- Staphylococcal infection of lambs (the bite gives the staph an area to enter), often following immunosuppression due to tickborne fever.
- Lambs are mainly affected at 2-12 weeks old with abscesses developing throughout the body, often in joints, tendons, muscle and brain.
- Lambs may display severe lameness, paralysis of the backend and death in severe cases. Up to 30% of lambs in a group may be affected.
what are the control techniques for ticks in sheep?
Host Control
* Avoid buying in naïve animals
* Synthetic pyrethroids (deltamethrin and cypermethrin)
◦ Better operator safety than OP dips and longer protection, but no immediate kill.
* Organophosphate dips
◦ Requires care with application, but also protects against blowfly strike, scab, lice and keds. Also provides immediate kill. but don’t last as long
Environment Control
* Active and start to feed in early spring – expose lambs while they have some passive protection.
* Avoid tick prone pastures if possible?
◦ Attempts to decrease tick population = pasture improvement
‣ drainage and scrub clearance
what do you need to do if you find sheep scap psoroptes ovis in the UK, how is this differen tin scotland?
- Notifiable in Scotland
- Legal requirement to treat or slaughter in all parts of the UK
