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Y4 Farm - Lameness > Infectious causes of lameness > Flashcards

Infectious causes of lameness Flashcards

1
Q

Bovine digital dermatitis - background

A
  • also called ‘Mortellaro disease’, ‘Papillomatous digital dermatitis’, ‘digital papillomatosis’, ‘raspberry heel’, ‘hairy heel warts’, ‘verrucose dermatitis’
  • now endemic in the UK
  • cattle (dairy & beef), sheep, goats
  • herd prevalence can exceed 30% (up to 50%)
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2
Q

Bovine digital dermatitis - impact

A
  • animal (& human welfare): uncomfortable and painful (active stages), decrease farmer morale
  • economic: DD-affected cow £335.15
  • production: 0.5-0.75kg/ day milk loss
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3
Q

Bovine digital dermatitis - aetiology

A
  • 3 groups of anaerobic spirochetes bacteria repeatedly found in lesions
    – group 1: Treponema medium / vicentii-like
    – group 2: Treponema phagedenis like
    – group 3: Treponema pedis (previously T.denticola/putidum)
  • bovine foot/skin microbiotia
  • +/- opportunist spirochetes bacteria invaders
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4
Q

Bovine digital dermatitis: bacterial survival

A
  • aerobic bovine faeces for 1d (15 mins - 6d)
  • viable on hoof knife blades for 2h
  • survive in pH 5.5-9.0 anaerobic culture
  • not viable after 15 mins in aerobic straw or sand (5% lime)
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5
Q

Bovine digital dermatitis - epidemiology

A
  • lesion on infected animal main reservoir (possibly only)
  • the slurry may be a reservoir of infection (footprint)
  • lesions can develop within 21 days (inoculation)
  • initial skin pathology to clinical lesion: 133d (average)
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6
Q

Bovine digital dermatitis - clinical signs

A
  • typical: appear on the plantar surface of the hind foot (95%)
  • occasional: heal bulb, interdigital space between claws, coronary band at the front of the foot, around accessory digits
  • hind foot ~80-90% vs front feet ~10-20%
  • mild lameness -> moderate/severe if treated
  • only 39% of cows with severe lesions are associated with lameness, with the risk of underestimating the PDD true herd prevalence
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7
Q

Bovine digital dermatitis - M-score M0

A
  • normal, healthy skin
  • no visible lesion
  • no sign of dd
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8
Q

Bovine digital dermatitis - M-score M1

A
  • early stage
  • focal active
  • red-grey
  • surface is moist
  • less than 2cm diameter
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9
Q

Bovine digital dermatitis - M-score M2

A
  • acute
  • bright red or red-grey
  • ulcerative
  • painful lesion
  • more than 2cm diameter
  • can have a proliferative stage as well (excessive hyperkeratotic epidermal growth), is sometimes accompanied by increased heel height
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10
Q

Bovine digital dermatitis - M-score M3

A
  • healing
  • non-painful
  • firm brown/black scab
  • often seen after topical tx
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11
Q

Bovine digital dermatitis - M-score M4

A
  • chronic stage
  • non-painful
  • dys/hyper-keratotic overgrowth
  • brown-grey colour
  • clearly circumscribed lesion
  • ‘wart-like’ overgrowth
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12
Q

Bovine digital dermatitis - M-score M4.1

A
  • chronic M4
  • with reactivation M1
  • i.e. chronic M4 stages showing a new red M1 lesion developing within the M4 lesion
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13
Q

Bovine digital dermatitis - diagnostics

A
  • clinically, the observation trimming chute is considered the gold standard
  • milk parlour scoring, but cannot assess front feet in the parlour
  • mirror
  • boroscope
  • bulk tank milk: antibodies, can differentiate between prevalence of less than 10%, 10-40%, 40+%, not often used
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14
Q

Bovine digital dermatitis - individual treatment

A
  • clean, remove matted hair and scab
  • dry the lesion
  • apply topical: antibiotic or non-antibiotic tx
  • +/- bandage – remember to remove
  • repeat applications (e.g. 3d) to improve recovery
  • parenteral antibiotics are effective but may not be cost effective or justifiable
    – antibiotics with lowest MIC for treponema’s include penicillin, ampicillin and oxytetracycline
  • care: spread of infection to other animals on foot trimming equipment (disinfect tools)
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15
Q

Bovine digital dermatitis - M1 lesion tx

A
  • non-antibiotic treatment (e.g. Chelate copper-zinc Gel, salicylic acid powder)
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16
Q

Bovine digital dermatitis - M2 lesion tx

A
  • spray licensed antibiotic (oxygen/chlor-tetracycline, thiamphenicole)
17
Q

Bovine digital dermatitis - M3 lesion tx

A
  • no tx
18
Q

Bovine digital dermatitis - M4 lesion tx

A
  • non-antibiotic treatment (e.g. Chelate copper-zinc Gel, salicylic acid powder)
19
Q

Bovine digital dermatitis - M4.1 lesion tx

A
  • non-antibiotic treatment (e.g. Chelate copper-zinc Gel, salicylic acid powder)
20
Q

Bovine digital dermatitis - prognosis

A
  • if tx early it can be good
21
Q

Bovine digital dermatitis - footbath

A
  • 1L solute per cow passage
  • has to be: 50cm wide, 300cm long, 12cm deep, volume of 180L, must be cleaned and refilled after a max of 180 cow passes
  • chronic lesion major reservoir (although bacterial load in acute lesion is higher)
  • to limit the progression of the early stages (M1) to clinical disease (M2) and the recrudescence of inactive (M3 and M4) lesions
  • most common chemical used: copper sulphate (4-5%), formaldehyde (2-4%)
  • antibiotic footpaths: historically widely practiced, now considered unacceptable
22
Q

Bovine digital dermatitis - risk factors

A
  • poor hygiene
  • poor biosecurity
  • irregular foot bathing
  • moisture
  • equipment e.g. knife for all cows without disinfection between
  • floor surfaces
  • stocking density
  • dirty feet
  • poor monitoring
  • parity & lactation: dry cows less prone due to cleaner environment, commonly affected when moving from young stock farm to milking shed, first parity considered to have less immunity
23
Q

Interdigital necrobacillosis - aetiology

A
  • other names: footrot, foul, foul in the foot, claw ill, lower
  • fusobacterium necrophorum (gram-negative); 2 subspecies:
    – F. necrophorum spp necrophorum (formerly biotype A)
    – F. necrophorum spp funduliforme (formerly biotype B)
  • synergistically acting with Porphyromonas levy and Prevotella intermedia
  • +/- secondaries (A. pyogenes, Streptococcus spp.)
24
Q

Interdigital necrobacillosis - clinical signs

A
  • damage to the skin - rough underfoot condition e.g. stubble, coarse straw
  • sudden onset moderate to severe lameness
  • anorexia, drop in milk yield, weight loss and pyrexia
  • swelling of soft tissues above and around the coronary band and between the digits
  • hot, inflamed, painful
  • ‘split’ in interdigital space, which discharges pus and necrotic tissue
  • characteristic foul smell
  • swelling may track higher up the leg as the infection invades
25
Q

Interdigital necrobacillosis - risk factors

A
  • poor surfaces (abrasive, cutting, such as stones, poor tracks)
  • poor hygiene
  • warm, moist environmental conditions
  • other causes of lameness increase the risk of the dz
  • beginning of lactation (metabolic status)
26
Q

Interdigital necrobacillosis - diagnostics

A
  • signs are pathognomonic
  • swelling of soft tissue
  • painful on palpation
  • severe lameness (AHDB score 2/3)
  • swabs/biopsy can be used (suitable transport medium)
27
Q

Interdigital necrobacillosis - tx

A
  • wash and flush with plenty of clean water
  • debridement of necrotic tissue if present
  • NSAIDs
  • parenteral AB for 3-5d
    – sulphamethoxypyridazine
    – oxytet
    – penicillin/streptomycin combinations
    – tylosin
28
Q

Interdigital necrobacillosis - prognosis

A
  • good if treated early
  • otherwise poor
  • deep digital sepsis can result in aggressive cases or if left untreated
  • progression of the swelling can cause separation of the digit
29
Q
A

Y4 Farm - Lameness (11 decks)

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