Farm animal skin disease Flashcards Preview

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Flashcards in Farm animal skin disease Deck (38):
1

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)

2

Dx - skin disease

Hx
CS + phases of presentation
Skin scrape (until bleeding)
Microbiology)
Case vs. herd

3

External parasites affecting farm animals

* Lice
* Mites
- flies
- midges
- (ticks - usually local irritation only)

4

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)

5

Name cattle lice

* Bovicola bovis* (CHEWING, rest are sucking)
- Linognathus vituli
- Haematopinus eurysternus
- Solenopotes capillatus

6

How do you tell apart chewing and sucking lice

CHEWING: narrrow head
SUCKING: broad head

7

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)

8

Epidemiology - lice

- numbers increase in cool months
- peak in early spring
- decline with coat shedding, solar radiation, high temps
- commonest in housed cattle

9

Dx - lice

- visible to naked eye (good light)
- microscope (differentiate type)

10

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)

11

Name cattle mites

* Sarcoptes scabei *
- Chorioptes bovis
- Demodex bovis
- Psoroptes ocis

12

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)

13

Dx - sarcoptic mange

* CS *
- skin scrape (low ~, sample lesion margin)
- skin biopsy ( because burrowing mite)
- Differentiate from psoroptic and chorioptic mange

14

Tx - sarcoptic mange in cattle

MLs

15

Outline psoroptic mange - cattle

- occasional cases
- imported belgian blues
- beef > dairy
- hypersensitivity reaction
- long legs
- lesion appears more acute and severe than sarcoptes

16

CS - chorioptic mange in cattle

--> 'tail mange'
- HLs, udder, perineum, tail (head/neck)
- housed cattle
- v common
- pruritus (not severe)
- winter

17

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

18

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

19

Name 2 lice affecting sheep

* Bovicola ovis = Sheep body louse*
- Linognathus ovilus

20

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/

21

Epidemiology - sheep body louse

- number increase in long-wool
- decline dramatically at shearing
- reduced by solar radiation (unless protected by fleece)

22

Dx - sheep body louse

Part wool and examine the near skin (lice should be visible)

23

Tx - sheep body louse

- shear
- apply insecticides (pour on OR saturation dip but only once)

24

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.

25

List sheep mites - 5

* Psoroptes ovis (main mite in sheep)*
- Sarcoptes scabiei
- Demodex ovis
- Psorobia ovis
- Chorioptes bovis (bovine tail mange)

26

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

27

Epidemiology - sheep scab / psoroptic mange

- mites can multiply very rapidly
- winter more favorable to mite than summer
- sometimes infections are latent over summer

28

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

29

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

30

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

31

Another name for blowfly strike

cutaneous myiasis

32

Outline blowfly strike

- UK important
- sheep distress
- slow death
- much loss of productivity
- prevention very costly

33

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

34

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)

35

Prevention - blowfly strike

- lamb tail docking to reduce 'breech strike'
- Cyromazine (Vetrazin) / Cypermethrin

36

Which lice affects pigs?

one species only - Haematopinus suis
very large
can transmit ASF and swine pox

37

Tx - Haematopinus suis - pigs

- OPs, twice, 14 d interval
- Also MLs (blood-sucking)

38

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