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FARM ANIMAL > 3.1.4: Farm animal dermatology > Flashcards

3.1.4: Farm animal dermatology Flashcards

1
Q

Where are Chorioptes mites generally found?

A
  • On and around the tail head
  • Cases are generally self-limiting
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2
Q

What is the causative agent of sheep scab?

A

Psoroptes ovis (mite)

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3
Q

Clinical signs of biting lice

A
  • Decreased BCS/ DLWG -> too busy itching to eat
  • Damaged skins/ fleece damage and loss
  • Pruritus
  • Excoriation
  • Severe infestations can result in anaemia
  • Biting lice can look similar to sheep scab but sheep don’t itch as much as they do with scab
  • May be asymptomatic
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4
Q
A

Lice in cattle
Bovicola bovis
* Commonest
* Chewing louse
* Found on head

Haemtopinnus eurysternus
* Sucking louse
* Found around the horns

Linognathus vituli
* Sucking louse
* Found around the head area

Images: hair loss, skin is not too erythematous

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5
Q

True/false: lice are very common and a concern for mixed-species farms.

A

False
* Lice are very common!
* However they are species-specific so not a concern for mixed species.
* Lice cannot live off the host. They are typically worst in winter when cows have thick coats. Sheep-shearing in summer decreases the population by 30-50%.

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6
Q

Diagnosis of lice

A
  • Visual inspection - can be seen with the naked eye
  • Direct microscopy of hair samples
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7
Q

How can you treat mites in cattle?

A

Options
* Pour-on synthetic pyrethroid e.g. deltamethrin - kills everything
* Pour-on group 3-ML anthelmintics e.g. ivermectin, doramectin, eprinomectin -> kills everything
* Injectable group 3-ML anthelmintics e.g. ivermectin, doramectin, eprinomectin -> removes all suckling lice and >98% biting lice

All cattle must be treated - treat at start of winter housing period.

Consider the impact on GI parasite resistance with these different options.

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8
Q

Deltamethrin is
a) a synthetic pyrethroid
b) a group 3-ML anthelmintic
c) a group 2-LV anthelmintic

A

a) a synthetic pyrethroid

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9
Q

Ivermectin, doramectin and epinomectin are all examples of:
a) Synthetic pyrethroids
b) Group 1-BZ anthelmintics
c) Group 2-LV anthelmintics
d) Group 3-ML anthelmintics

A

d) Group 3-ML anthelmintics

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10
Q

What options do you have for treating lice in sheep?

A

Options
* Pour-on synthetic pyrethroid e.g. deltamethrin, cypermethrin -> kills biting lice
* Organophosphate dips -> kills everything including humans so take care to ensure correct usage and PPE

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11
Q

Flies can act as vectors for which bacterial ocular disease in cattle? What is the causative agent?

A

Infectious bovine keratoconjunctivitis (IBK)
a.k.a. Pinkeye disease
* Causative agent = Moraxella bovis
* Vector: face fly, feeds on tears and rapidly spreads throughout herd

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12
Q

Clinical signs of IBK

A
  • Corneal ulcers
  • Oedema
  • Lacrimation
  • Opacity
  • Epiphora
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13
Q

Treatment and control of IBK

A
  • Antibiotics (oxytetracycline or penicillin): IM injection is equally as effective as subconjunctival
  • NSAIDs (meloxicam)- very painful!

Control
* Fly control e.g. fly tags/ pour-on synthetic pyrethroids e.g. permethrin -> lasts for several months

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14
Q

What are Onchocerca and what are the clinical signs of infection? How do you treat this?

A

Onchocerca: thin, white worms found in the eye of cattle.
* Vectors: blackfly, Culicoides
* Causes ocular infection: acute oedematous necrosis to chronic granulomatous changes, marked fibrosis and mineralisation
* Treatment: systemic ivermectin + NSAIDs
* Not currently present in UK

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15
Q

Species of blowfly

A
  • Lucilia spp
  • Calliphora spp
  • Phormia spp.
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16
Q

Risk factors for blowfly strike

A
  • Climatic conditions (warm and wet)
  • Breed susceptibility (heavy dense fleece)
  • Wet or dirty fleece -> easy for larvae to survive (dirty fleece may be caused by PGE)
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17
Q

Clinical signs of blowfly strike

A
  • Agitated sheep with area of discoloured wool
  • If you itch the area, sheep nibbles in the air
18
Q

Treatment of blowfly strike

A
  • Insecticides: synthetic pyrethroids and organophosphates
  • Animals can be very sick -> electrolytes, propylene glycol, 3-5 days broad spectrum antibiotics (e.g. penicillin + something else)
  • NSAIDs (meloxicam)
19
Q

Prevention of blowfly strike

A
  • Long-acting synthetic pyrethroids and IGRs
  • Non-chemical prevention: genetic selection for wool-shedding breeds, early shearing, dagging, good endoparasite control
20
Q

Causative agent of warble fly

A
  • Hypoderma bovis
  • Hypoderma lineatum

Warble fly has been eradicated from the UK and all imported cattle must be treated on arrival. Still notifiable in Scotland.

21
Q

Clinical signs of warble fly

A
  • Gadding behaviour: flies harass cattle, causing them to become restless, charge around, become depressed -> reduced production and growth
  • Ectopic migration and paralysis -> risk if wrong treatment used! Larvae migrate to the wrong place and damage nerves.
  • Downgrade of hides caused by larvae
  • Reduced reproduction -> larvae emerge in spring -> cow will not stand to be mounted as painful
22
Q

Treatment of warble fly

A
  • Organophosphates 98% effective in autumn, less effective in spring
23
Q
A

Sarcoptes spp.

24
Q
A

Demodex spp.

25
Q
A

Chorioptes spp.

26
Q
A

Psoroptes spp.

27
Q
A

Sheep scab
Causative agent: Psoroptes ovis

Legal requirement to treat or slaughter in UK. Notifiable in Scotland.

28
Q
A

Psoroptes ovis
Causative agent of sheep scab

29
Q

True/false: Psoroptes ovis can survive off the host.

A

True
Mite can survive off the host for 15 days

30
Q

Clinical signs of sheep scab

A
  • Extreme pruritus
  • Rubbing
  • Head tossing
  • Wool loss
  • Wounds
  • Rapid loss of condition
  • May see seizures
31
Q

Diagnosis of sheep scab

A
  • Mites just visible to naked eye
  • Skin scrape around edge of lesion -> look on the leading edge (caudally or ventrally) because lesion starts on the shoulder
  • Blood coproantigen ELISA -> good for early disease (2 weeks post infection can be detected); can sample a portion of the flock and see if present
32
Q

Treatment options for sheep scab

A
  • Organophosphate plunge dipping (diazinon) -> need correct PPE and correctly dip sheep. The only way if you have ML-resistance.
  • ML injections but this does not provide much residual protection (doramectin/moxidectin provides some, ivermectin none) -> there is some resistance
33
Q

Control challenges of sheep scab

A
34
Q

Control of sheep scab

A
  • Quarantine treatment to avoid bringing in scab
  • OP dipping
  • Serology to detect infection early
35
Q
A

Chorioptic mange (a surface mite)

36
Q

Consequences of tick infestations

A
  • Spread of infectious disease
  • Poor BCS
  • Weight loss/ reduced milk yields
  • Hide/ fleece damage
  • Intense irritation -> associated behavioural issues
  • Lesions and opportunistic bacterial infections
  • Prolonged infestation -> small granuloma formation due to retention of mouth parts of salivary secretions
37
Q

Tick control

A
  • Avoid buying in naïve animals
  • Pour on synthetic pyrethroids e.g. deltamethin, cypermethrin OR organophosphate dips
  • Avoid tick-borne pastures if possible/ pasture improvement and scrub clearance
38
Q

Causative agent of tickborne fever

A

Anaplasma phagocytophilum (a rickettsia)

39
Q

What is tick pyaemia?

A
  • Lambs 2-12 weeks old
  • La,bs are infected by anaplasmosis and this causes immuno-suppression
  • There is then opportunistic by S. aureus through bite wounds/ umbilicus -> leads to abscesses
  • Can look like joint ill but tick pyaemia occurs at weeks (not days) old
40
Q

Clinical signs of Babesia in cattle

A

Babesia = redwater fever. Spread by ticks.
* Pyrexia
* Severe haemolytic anaemia -> haemoglobinuria
* Potentially death

41
Q

Types of photosensitisation

A
  • Direct photosensitisation: defect in metabolism of RBCs or plants e.g. St John’s wort
  • Secondary photosensitisation: animals will liver damage that means they do not breakdown chlorophyll adequately.
  • Local photosensitivity: reaction to the sap of some plants.
42
Q

Treatment of photosensitisation

A
  • NSAIDs
  • Removal to cool shaded housing
  • Fly control
  • Treatment of liver failure

FARM ANIMAL (56 decks)

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