Farm animal skin disease Flashcards
How are farm animal skin diseases classified? Examples?
PRIMARY - parasite (lice, mites), bacterial (erysipelas, dermatophilus), viral (CSF, PMWS/PDNS/PRRS), fungal (ringworm)
SECONDARY - underlying disease (photosensitivity), underlying deficiency (Cu)
Dx - skin disease
Hx CS + phases of presentation Skin scrape (until bleeding) Microbiology) Case vs. herd
External parasites affecting farm animals
- Lice
- Mites
- flies
- midges
- (ticks - usually local irritation only)
Tx - external parasites (cattle, sheep, pigs)
- MLs - ivermectin (injectable, pour-on)
- Synthetic pyrethroids (SP) - cypermethrin, deltamethrin
- Organophosphates (OP) - diazinon
- Amidines - amitrax
- IGRs - cyromazine (‘Vetrazin’ pour on)
Name cattle lice
- Bovicola bovis* (CHEWING, rest are sucking)
- Linognathus vituli
- Haematopinus eurysternus
- Solenopotes capillatus
How do you tell apart chewing and sucking lice
CHEWING: narrrow head
SUCKING: broad head
CS - lice
- pruritus (especially B. bovis)
- hair loss (rubbing, neck, back, shoulders, flank, tail base)
- anaemia (sucking lice)
- winter
- heavy infections only (severe)
- productivity affected (small liveweight gain change, variation)
- leather affected (‘light spot and fleck’ decreases value)
Epidemiology - lice
- numbers increase in cool months
- peak in early spring
- decline with coat shedding, solar radiation, high temps
- commonest in housed cattle
Dx - lice
- visible to naked eye (good light)
- microscope (differentiate type)
Tx- lice
JUSTIFIED?
- peak # and CS often precede natural decline
- sucking lice (esp calves or debilitated animals) warrant tx
- best time to tx is autumn (no lice visible, numbers low)
- MLs very effective (kill all sucking lice - injection and pour on), reduce B.bovis dramatically (pour on only)
- SP pour ons too (deltamethrin, cypermethrin)
Name cattle mites
- Sarcoptes scabei *
- Chorioptes bovis
- Demodex bovis
- Psoroptes ocis
Describe bovine sarcoptic mange
- Sarcoptes scabei
- causes ‘head and tail’ mange
- housed cattle
- head and neck low # but problem is hypersensitivity
- any age
- severe and acute onset possible
- TRANSMISSION: direct contact, fomites (a few days)
Dx - sarcoptic mange
- CS *
- skin scrape (low ~, sample lesion margin)
- skin biopsy ( because burrowing mite)
- Differentiate from psoroptic and chorioptic mange
Tx - sarcoptic mange in cattle
MLs
Outline psoroptic mange - cattle
- occasional cases
- imported belgian blues
- beef > dairy
- hypersensitivity reaction
- long legs
- lesion appears more acute and severe than sarcoptes
CS - chorioptic mange in cattle
- -> ‘tail mange’
- HLs, udder, perineum, tail (head/neck)
- housed cattle
- v common
- pruritus (not severe)
- winter
CS - demodectic mange - cattle
- common, rarely diagnosed
- hide damage (greatest problem)
- NO pruritus
- LITTLE hair loss
- occasionally develop into multiple nodules +/- secondary infection (face, neck, shoulders)
- blotchy lesions
Outline warble fly -cattle
- not a strict parasite (can complete LC without cow)
- notifiable
- flies lay eggs –> irritation, larval migration –> decreased growth/production, larvae reach skin –> extensive damage
Name 2 lice affecting sheep
- Bovicola ovis = Sheep body louse*
- Linognathus ovilus
CS - sheep body louse (Bovicola ovis)
- SEVERE fleece derangement
- rubbing, biting wool
- more important in merinos and related
- increased incidence in UK since compulsory dipping stopped/
Epidemiology - sheep body louse
- number increase in long-wool
- decline dramatically at shearing
- reduced by solar radiation (unless protected by fleece)
Dx - sheep body louse
Part wool and examine the near skin (lice should be visible)
Tx - sheep body louse
- shear
- apply insecticides (pour on OR saturation dip but only once)
Describe saturation dips
- for tx of sheep body louse
- do once (fats in wool allow slow release of chemical)
- plunge
- showers and spray races not encouraged in UK anymore and no products available.
List sheep mites - 5
- Psoroptes ovis (main mite in sheep)*
- Sarcoptes scabiei
- Demodex ovis
- Psorobia ovis
- Chorioptes bovis (bovine tail mange)
CS - sheep scab /psoroptic mange
- pustules, then spreading moist lesions
- fleece becomes matted
- extereme pruritus
- can become very extensive
- NOTIFIABLE in Scotland (recent eradication)
- mites visible with naked eye, just (smaller than lice)
- severe –> thin sheep + death
Epidemiology - sheep scab / psoroptic mange
- mites can multiply very rapidly
- winter more favorable to mite than summer
- sometimes infections are latent over summer
Tx and control - sheep scab
- plunge dip (OP solution)
- ML (injection)
- (pour-on tx NOT effective)
- (spray races and showers NOT effective as would require dipping for 1 minute, cypermethrin withdrawn in UK)
- pastures, fences, buildings are a source of reinfection for up to 15 days
Describe plunge dips and sheep scab
- WON’T work if tx time too short (1 minute), heads not wet (dipped twice), dip becomes heavily fouled, strength is too low or not replenished properly
- uses Diazonin (an OP) - nasty so PPE essential
List MLs for tx of sheep scab
- Doramectin (IM, once, 300microg/kg)
- Ivermectin (SC, twice, 7 d apart, 200 microg/kg)
- Moxidectin (SC, twice, 10d apart, 200 microg/kg for 28 d, lasts 28 d for prevention)
- THESE DRUGS ARE FOUR TIMES THE PRICE OF PLUNGE DIPS
Another name for blowfly strike
cutaneous myiasis
Outline blowfly strike
- UK important
- sheep distress
- slow death
- much loss of productivity
- prevention very costly
Where does blowfly strike affect?
SHEEP. primary flies lay eggs in moist wool, inflamed
- PREDILECTIONS: breech (faeces), body, wounds, head (base of horns)
- larvae feed on skin surface –> extensive skin damage
- toxaemia follows due to skin necrosis and absorption of bacterial toxins
- secondary/ tertiary flies may invade subsequently
Tx - blowfly strike
- clip surrounding hair
- clean tissue
- remove visible maggots
- apply insecticide (Coopers Spot on = deltamethrin)
- supportive tx sometimes indicated in severe cases (AB)
Prevention - blowfly strike
- lamb tail docking to reduce ‘breech strike’
- Cyromazine (Vetrazin) / Cypermethrin
Which lice affects pigs?
one species only - Haematopinus suis
very large
can transmit ASF and swine pox
Tx - Haematopinus suis - pigs
- OPs, twice, 14 d interval
- Also MLs (blood-sucking)
What mite affects pigs?
Sarcoptes scabei
- sarcoptic mange is serious
- chronic - severe hyperkeratinisation
- ivermectin effective
- 10-60% prevalence
- affects piglet growth
- eradicated in some countries
