Parasite skin diseases of cattle

Question 1

parasites infections of cattle of most concern to us

Answer 1

• Warbles
• Lice!
• Chorioptes!
• Sarcoptes
• Psoroptes
• Demodex

Question 2

macrocyclic lactones for cattle and admin methods

Answer 2

1. ivermectin > pour-on, injection
2. doramectin > injection
3. eprinomectin > pour-on, injection

Question 3

ivermectin milk and meat withdrawl

Answer 3

POUR-ON
- milk withdrawl: 60 days
- meat withdrawl: 49 days
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INJECTABLE
- milk withdrawl: 60 days
- meat withdrawl: 35 days

Question 4

doramectin milk and meat withdrawl

Answer 4

INJECTABLE
- milk withdrawl: 60 days
- meat withdrawl: 40 days

Question 5

eprinomectin milk and meat withdrawl

Answer 5

POUR-ON
- milk withdrawl: 0 days
- meat withdrawl: 0 days
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INJECTABLE
- milk withdrawl: NA
- meat withdrawl: 120 days

Question 6

hypoderma bovis and lineatum
- what are they?
- when do we see them?

Answer 6

• Hypoderma bovis (northern cattle grub)
• Hypoderma lineatum (common cattle grub, heel fly)
• used to be seen February-April in southern Ontario
• now very uncommon - more common < 2 years of age

Question 7

hypoderma species cause what lesion? due to what part of their life cycle?

Answer 7

subcutaneous swellings = “warbles”
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- cutaneous perforation (1-2 months)
- larva emerges and pupates in ground (~5 weeks)
> hypoderma bovis, hypoderma lineatum

Question 8

H. bovis
- how and where they lay eggs?
- winter resting site?

Answer 8

H. bovis
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eggs laid:
- singly
- lower / upper body
> hatch in a few days
- move winter resting site in epidural fat in spinal canal (late fall, stay for 2-4 months)
> migration to skin (feb-march)

Question 9

H. lineatum
- how and where they lay eggs?
- winter resting site?

Answer 9

H. lineatum
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eggs laid:
- in rows
- legs / lower body
> hatch in a few days
- move winter resting site in esophageal submucosa (late fall, stay for 2-4 months)
> migration to skin (feb-march)

Question 10

pathogenic significance of hypoderma

Answer 10

1. Tissue damage > trimming
2. Downgrading of hide/carcass
3. Disturbance to cattle (“gad”)
   * decreased milk yield and growth rate

Question 11

hypoderma preventative therapy and timing

Answer 11

• after fly laying activity ceases BUT before larvae reach winter resting sites
• September to November in Ontario:
  Use systemic insecticide:
• all macrocyclic lactone formulations
  !!!Don’t treat with macrocyclic lactone December to February!!!

Question 12

adverse reaction following hypoderma treatment
when does it occur? what do we see?

Answer 12

(3 hours-3 days)
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1. Anaphylaxis-like reaction - rare
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2. Local inflammation
(a) vertebral canal syndrome (H. bovis):
- edema/inflammation > paresis, ataxia (b) esophageal syndrome (H. lineatum):
- edema/inflammation > dysphagia, drooling, bloat, metabolic acidosis

Question 13

pediculosis in cattle - clinical signs

Answer 13

• low numbers = subclinical
• restless, scratching, licking
• rough coat / poor condition
• alopecia
• hide damage
• anemia (sucking lice – calves)
• decreased milk and growth rate
• nits/lice?

Question 14

main biting louse of bovines? behaviour and anatomic locations?

Answer 14

• feed on exfoliated epithelium/ cutaneous debris
• very mobile
• Damalinia bovis - “cattle biting louse”
  > poll, shoulder, back, rump, tail

Question 15

main sucking lice of bovines? what do they feed on? what anatomic locations do they like best?

Answer 15

• feed on blood + tissue fluid
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  (a) Linognathus vituli - “long nosed cattle louse”
  – shoulder, back, rump, ribs, abdomen
  (b) Solenopotes capillatus - “little blue cattle louse”
  – muzzle, neck
  (c) Haematopinus eurysternus - “shortnosed cattle louse”
  – poll, neck, shoulder, back, tail head

Question 16

pediculosis epidemiology, life cycle and seasonality

Answer 16

• confined to host
• eggs (“nits”) hatch in 5-14 days
• egg > adult = 3-6 weeks
• young cattle – more heavily infested
• breed in narrow temperature range
  > seasonal periodicity:
• very low numbers in summer
• breeding starts in fall
• heaviest infestation – winter/early spring
• apparent self-cure in spring

Question 17

pediculosis treatment and control?

Answer 17

• if clinical, treat all animals in group at same time
• if short residual activity retreat in 14-16 days - not necessary with ivermectin pour-on as significant residual activity
• examine quality of nutrition
• single preventive treatment in fall / when housed for winter
• macrocyclic lactone pour-ons: biting + sucking lice
• macrocyclic lactone injectables: ONLY sucking lice

Question 18

good pour-on options for pediculosis in lactating cattle? what is their residual activity?

Answer 18

• eprinomectin - Eprinex Pour-On
• permethrin - Boss Pour-On, Vetolice
• cyfluthrin - CyLence Pour-On
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• No residual activity for any of these (retreat in 14-16 days)

Question 19

Beef cattle – additional compounds for lice aside from those used in dairy:

Answer 19

(a) Pour-ons:
* ivermectin
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(b) Injectables: (ONLY for sucking lice)
* ivermectin, doramectin
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(c) Back rubber - malathion

Question 20

chorioptic mange of cattle
- how common?
- who gets it?
- lesions?
- dx
- signs

Answer 20

• commonest mange of cattle
• usually housed animals (dairy cattle)
• lesions - tail head, perineum > ?
• tend to remain localised
• allergic exudative dermatitis
• usually a few animals in group = clinical
• scrapings: large #s mites
• pruritus > economic impact ?

Question 21

chorioptes bovis - epidemiology
- when do we see them? when dont we?
- signs?
- transmission?
- age?

Answer 21

• more active late winter/early spring
• generally disappears at pasture in summer
• infected animals commonly subclinical * summer persistence = pasterns ?
• transmission = direct contact + ?
• rare on animals < 6 months

Question 22

chorioptes - preventative treatments, timing

Answer 22

• fall
• treat all/some cattle + clean environment ?
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  1. Macrocyclic lactone pour-ons
  2. Permethrin - Vetolice, Boss Pour-On > these are extra-label but have sero milk withdrawl
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• eradication from herd = problematic

Question 23

sarcoptic mange in cattle
- pathogen
- how common?
- significance?
- site preference?

Answer 23

Sarcoptes scabiei var bovis
* uncommon
* potentially severe mange
* site preference of mite ?
– neck, brisket, inner thighs, root of tail > whole body
* zoonotic
Note: not reportable in USA or Canada

Question 24

Sarcoptic mange - cattle
- clinical signs and impact

Answer 24

• red papules + erythema
• intense pruritus
• thickened skin, alopecia
• scabs on skin
  …………V…………
  (a) decreased milk yield, weight loss
  (b) decreased growth rate
  (c) downgrading of hide

Question 25

sarcoptes life cycle, activity, transmission, who is susceptible

Answer 25

• life cycle = 10-14 days
• adult mites don’t survive > few days off host
• most active in cold, wet weather
• transmission mainly by direct contact ?
• poor condition = more susceptible

Question 26

sarcoptes diagnosis

Answer 26

• large # deep skin scrapings

Question 27

sarcoptes treatment

Answer 27

1. All macrocyclic lactone formulations
2. (a) clean/disinfect all pens
   (b) leave building vacant + dry for 3 weeks

Question 28

Psoroptic mange (Psoroptes ovis)
- how common
- site preference
- signs

Answer 28

• very uncommon
• site preference ?
  – neck, withers, root of tail > generalised
  – persistent intense pruritis

Question 29

psoroptes epidemiology
- how they cause damage
- life cycle length
- transmission
- optimal environment

Answer 29

• piercing mouthparts > skin damage
• hypersensitivity to saliva/feces antigens
• life cycle = 10-20 days
• transmission = direct + indirect
• optimum condition = moist + cool temperature

Question 30

Psoroptes Dx

Answer 30

• mites readily demonstrated in scrapings
  Note: not reportable in USA or Canada

Question 31

demodex bovis
- how common
- signs
- sites
- lesions
- who gets them?
- transmission

Answer 31

• uncommon ?
• usually subclinical
• papules/pustules (1-30 mm)
• brisket, lower neck, forearm, shoulder
• usually no alopecia/pruritus
• hair follicles/sebaceous glands distended – cheesy content
• nodules typically do not persist > 7 weeks
• typically adult dairy cattle – late winter, spring
• transmission = direct contact