Lameness in cattle Flashcards
Distribution of lameness causes
> 90% from hoof and hoof skin
Of this 85% is hind feet and 15% front feet
Within hind feet, 85% related to LATERAL claw vs in front feet, lateral and medial = distribution
What is the suspensory apparatus of the hoof
Dense collagenous fibres that extend from P3 to lamellae of hoof wall to supend P3 within hoof capsule
What is the white line
= junction between the wall and the sole
Rate of hoof production by the corium and how does this change after parturition
5mm/month
- Slows down after parturition
How does the cow mobility score work
From 0-3
0 = good mobility
1 = slight impairment but affected limb not obvious; use preventative measures
2 = impaired mobility where affected limb identifiable - get seen within 48 hours
3 = severely impaired mobility; should be seen within 24 hours
Should ideally be done on whole herd every 2 weeks
4 most common conditions causing foot lameness
Sole ulcer
White line disease
Digital dermatitis
Foul of the foot
Basics of how sole ulcers form
Failure of suspensory apparatus + inadequacy of digital cushion changes pedal bone support
-> Allows movement of bone within hoof capsule
Get excessive force on horn producing tissues; causes sole ulcers
What can cause inadequacy of digitial cushion
In severe negative energy balance, fat may be mobilised from here
What causes white line disease
Shearing forces; when moving in unnatural directions e.g backwards or sharp exits
+ poor surfaces can tear wall from sole and weaken the white line
Factors causing failure of the suspensory apparatus
1) Laminitis: inflammation in hoof capsule due to endotoxins (e.g from metritis/toxic mastitis) + lactate, histamine (can enter circulation following ruminal acidosis); causes disruption of microcirculation in chorium; get inflammmation, ischaemic damage, oedema, haemorrhage
-> THEN: MMPs are activated which degrade collagen in apparatus
2) Hoofase = substance in hooves of periparturient animals which activates MMPs
3) Oestrogens and relaxin; released around parturition to loosen pelvic ligaments but also at on foot ones
What does position of ulcers on foot relate to
MOvement of P3
- Downward displacement/rotation –> sole haemorrhage and ulcer
- Rotation of apex causes toe ulcer
- Sinking of rear portion gives heel ulcers
Why do we get more lameness from back feet
Due to attachment of the limbs
- IN front limb the muscle-tendon sinew at shoulder acts as a shock absorbant
- IN back limbs it is skeletal attachment so shock stays in leg
Why do we get more lameness from lateral claw on back legs
Because longer than medial so more weight bearing
How can subacute ruminal acidosis affect hoof horn keratin
Production requires biotin (vit B7, vit H) which is made by ruminal microbes
- BUT don’t make as much with acidosis
What is the key predisposing cause to claw horn lesions in cattle
confinement on hard usrfaces
Why do cows go lame 2 months after parturition
Because all the risk factors are around parturition BUT takes time for deficity in hoof horn growth to show
Risk factors around parturition
> Relaxins and oestrogens cause loosening of suspensory apparatus
Risk of toxic mastitis/metritis + ruminal acidosis can contribute to laminitic changes
Standing for long periods on concrete yards for milking
Body condition loss in early lactation can cause loss of digital cushion function
What are the causative agents in digital dermatitis
Spirochetes treponema species
- Then get secondary invasion from others e.g Fusobacterium, campylobacter
M0-M4.1 scoring of digital dermatitis
0 = normal
1 = early lesions <2cm
2 = acute, active ulcerative lesions >2cm
3 = healing stage; covered in scab
4 = late chronic lesions; may be dyskeratotic or proliferative
M4.1 = CHORNIC M4 stage AND acute M1 stage
WHen to change foot bath
After 1 cow passage/L
Treatment for digitial dermatitis
Individuals: give local antibiotics and antisepsis
- If not working can give pencillin/cephalosporin systemically
Types of foot baths and size they should be
Formalin, copper, Zn, paracetic acid
should be >10cm deep to cover coronary band + 3m long to allow several steps to be taken