Lameness (Yr 4) Flashcards
what are the common causes of lameness in sheep relating to the feet?
footrot (scald, benign, virulent)
CODD
white line disease
toe granuloma
foot abscess
interdigital hyperplasia
overgrown, foreign bodies
what is benign footrot also known as?
scald or interdigital dermatitis
what is the main pathogen associated with scald (benign footrot)?
Dichelobacter nodosus (also Fusobacterium necrophorum)
what are the clinical signs of scald (benign footrot)?
lameness
interdigital skin inflamed/discharging
smells
(no horn under-running or separation)
what predisposes sheep to benign footrot (scald)?
interdigital moisture/damage (warm wet conditions)
high stocking rates (housing)
what is virulent footrot?
interdigital dermatitis plus progressive under-running of sole starting medially
how do horns with virulent footrot appear?
grey necrotic pungent smelling sole
what is the primary aetiological agent of footrot?
Dichelobacter nodosus
is Dichelobacter nodosus anaerobic or aerobic?
anaerobic
what are the virulence factor of Dichelobacter nodosus?
fimbrae (allows movement)
proteases (necrosis of horn)
how can benign footrot (scald) be treated?
oxytetracycline spray
formalin/zinc sulphate foot bath
(systemic antibiotics not necessary)
how is virulent footrot treated?
long acting oxytetracycline or amoxicillin (first line)
macrolides if you want longer acting (tilmicosin…)
do not trim
treat quickly and isolate
should lame sheep with footrot have their feet trimmed?
no - delays healing and spreads disease
what does CODD stand for?
contagious ovine digital dermatitis
how lame are sheep with CODD?
severe lameness
how does CODD appear clinically?
ulcerative/proliferative lesion begins at coronary band
progressive under-running of hoof wall downwards
hoof sloughs off
how is CODD graded?
1 - coronary band lesion
2 - <50% horn capsule separated
3 - >50% hoof capsule separated
4 - healing but still active
5 - healed
can CODD lesions heal?
yes - but hoof often left deformed
how deep does infection of CODD spread?
can reach bone
what is the causative agent associated with CODD?
treponeme bacteria (same as digital dermatitis in cattle)
Dichelobacter nodosus and Fusobacterium necrophorum also found
what are the risk factors for CODD?
late summer to early autumn
lush, wet pasture with high stocking
how is CODD treated?
isolate
long acting amoxicillin (treat until cure)
macrolide for second line longer acting
what is the five point plan?
vaccinate twice yearly with footvax
treat lame sheep quickly
biosecurity
reduce environmental challenge
cull chronically lame sheep
what is footvax for?
footrot (Dichelobacter nodosus)
what can footvax be used for?
prevention and treatment of footrot (can be used in an outbreak)
some protection against CODD
what is the issue with the footrot vaccination?
oily adjuvant so can cause lumps/abscesses (don’t use near shearing or lambing)
what is the typical footvax protocol?
2 doses 4-6 weeks apart then 6 monthly boosters
what biosecurity should be taken for foot lesions for bought in stock?
isolate and treat with footvax
return if signs of footrot/CODD
what is white line disease?
separation of white line
when may white line disease lead to lameness?
when sensitive tissue gets exposed or impacted with stones/mud
abscess formation (tracks up the horn)
how can white line disease be treated?
no infection - leave or trim slightly
abscess - trim to drain pus
what causes a toe granuloma?
overtriming (chronic irritation/infection)
chronic foot disease
how are toe granulomas treated?
intravenous regional anaesthesia
cut off and cauterise granulation tissue
how is interdigital hyperplasia treated?
trim and clean
(antibiotics if secondary infection present)
what predisposes sheep to laminitis?
high energy/concentrate diet
how is laminitis treated?
treat underlying disease
NSAIDs
what causes a pedal joint abscess?
interdigital infection spreads into the interphalangeal joint structures, pus then tracks abaxially to emerge at the coronary band
what are the clinical signs of pedal joint abscesses?
severe lameness
swollen, warm foot
widened interdigital space
purulent discharge
how can pedal joint abscesses be treated?
flush and antibiotics
digit amputation
where do you disarticulate for a digit amputation?
between P1 and P2
what is strawberry footrot?
proliferative scab lesion of distal limb usually caused by orf or dermatophillus
how is strawberry footrot treated?
systemic/topical antibiotics (penicilin)
move to dry area
what causes white muscle disease?
selenium and vitamin E deficiency
what animals is white muscle disease seen in?
young, rapidly growing lambs
how does white muscle disease present?
stiff and reluctant to move
swollen/painful skeletal muscles
how can white muscle disease be diagnosed?
raised glutathione peroxidase in blood
what are some causes of infectious arthritis?
neonatal infections (Streptococcus dysgalactaie)
tick pyaemia (Staphylococcus aureus)
Erysipelothrix
