Non-infectious causes of lameness in cattle

Question 1

General causes of lameness

Answer 1

• sole ulceration
• white line dz
• digital dermatitis
• local sole bruising
• foul in the foot
• interdigital hyperplasia
• FB penetration
• heel horn erosion
• heel abscess

Question 2

Claw horn lesions - 2 examples

Answer 2

• sole ulceration
• white line dz

Question 3

Historical view of laminitis linked to claw horn disruption lesions

Answer 3

• initial systemic metabolic insult (rumen acidosis) causing vascular dysfunction in the hoof
  -> degeneration at the dermal-epidermal junction in the laminar region of the hoof and loss of structural integrity
  -> movement of P3 with compression of the sole corium
  -> development of lesions in the horn capsule; discolouration in the sole and white line
• but laminitis doesn’t correctly describe the pathology i.e. there is no inflammation of the laminae
• it has not proved possible to induce/reproduce this aetiology experimentally

Question 4

True or false: acidosis is not a primary cause of sole haemorrhages

Answer 4

• true

Question 5

Aetiology and pathogenesis of claw horn lesions

Answer 5

• claw horn dz is a pressure lesion

Question 6

What causes excess pressure on the dermis?

Answer 6

• the calving effect: e.g. milk yield & energy balance
• environmental factors (including hoof overgrowth): e.g. standing/walking surfaces, standing/lying times, track surfaces/maintenance
• changes to the normal structures in the hoof: e.g. digital cushion thickness, BCS, previous lameness & long-term pathology

Question 7

The digital cushion

Answer 7

• 3 cylindrical parallel orientated bodies
• capsule of connective tissue filled with fat
• high in mono unsaturated fat
• fully develop during the 2nd lactation (fat content increases with age)
• the thickness of the digital cushion is linked to BCS (fat cow = thick cushion, thin cow = thin cushion)

Question 8

Normal weight bearing

Answer 8

• heel bulbs (particularly the lateral claw) makes 1st contact (elastic horn reduced initial shock)
• digital cushion and sole and heel dermis act to dissipate concussive forces
• elastic tissues expand laterally when compressed transferring energy to the wall (high tensile strength)
• majority of weight then transferred to the wall
• weight distributed equally between claws (but medial claw slightly smaller)
• prolonged exposure to concrete flattens and increases the width of the lateral claw
• this transfers part of the load to central part of the sole increasing the pressure on the dermis
• overgrowth of the lateral claw further increases pressure in this area
• prolonged standing on hard surfaces increases the pressure on the dermis

Question 9

The suspensory apparatus

Answer 9

• collagen fibres run from P3 and anchored in the dermal lamellae and hence to the claw capsule
• suspend the pedal bone within the hoof capsule by transferring and distributing the load
• hence the suspensory apparatus determines the degree of compression of the sole dermis
• the quality of the collagen fibres and connective tissues is critical, any deterioration will cause sinkage and/or rotation of the pedal bone

Question 10

Bone changes to P3

Answer 10

• UoN research has demonstrated that animals with a lifetime hx of lameness have greater bone development on P3
• thought that new bone forms in response to an episode of claw horn lesion
• new bone formation is almost always associated with an inflammatory process and suggests that inflammation is a key component of the aetiopathogenesis of claw horn dz
• new bone exacerbates the problem further by compressing the germinal epithelium increasing the likelihood of dz

Question 11

What does the self-perpetuating downward spiral of dz explain?

Answer 11

• why dz is predominantly seen in older cows, and animals which have had previous lameness events
• once dz becomes chronic, cows are more difficult to tx and less likely to recover
• it often takes time for the benefits of herd intervention programmes to become apparent

Question 12

Treating claw horn lesions

Answer 12

• treatment trim + block + anti-inflammatory shows best results

Question 13

Impact of treating early

Answer 13

• shorter time to tx
• less severe foot lesions
• less likely to have future tx
• reduced prevalence of lameness at 4w
• delayed tx = poorer outcomes

Question 14

Early and effective tx

Answer 14

• requires regular mobility scoring = early detection
• lift and treat within 48h
• block and NSAID where necessary

Question 15

Risk factors for sole lesions

Answer 15

• walking and standing for long periods on hard surfaces, esp in the post-calving period
• hoof overgrowth
• periparturient increase in the movement of the pedal bone
• loss of fat from the digital cushion and new bone formation on P3

Question 16

Herd level control - preventing claw horn lesions

Answer 16

• promote lying -> cubicle comfort
• post-calving period -> cubicle training heifers, fresh cow groups
• limit standing times -> collecting yards (split cows into more groups or increase parlour size)
• surfaces -> rubber matting (throughout unit or where cows stand for long periods)
• cubicle size -> 90cm lunge zone, 10cm Bob zone
• NSAIDs at calving
• routine foot trimming
• provide periparturient animals with the best accommodation to minimise risk during this period
• minimise BCS loss to peak yield

Question 17

Cubicle training for heifers

Answer 17

• cubicle training during rearing
• provide at least 1 month in cubicles before they calve
• expose to concrete before they calve if they will be on concrete post-calving -> allows the foot to adapt to the post calving environment

Question 18

Cubicles for the fresh cow group

Answer 18

• provide ‘best’ cubicles at a low stocking rate or very clean straw yard for 4-6w after calving
• reduce pressure on feet during risk period
• reduces stress during the post calving period

Question 19

Routine foot trimming (aim, who, when)

Answer 19

• aim: to maintain optimal weight bearing and foot balance
• who? farm staff (with appropriate training), foot trimmers (must be trained, ideally fully qualified)
• when?
  1. timed trim: all feet of all cows examined and trimmed at specific time e.g. pre-calving, peak-lactation, dry off
  2. a number of cows with obviously overgrown feet selected on a routine bassi (therefore not all cows examined)
  3. all cows trimmed in batches (often by a lay foot trimmer)
  4. whole herd is trimmed annually by a lay foot trimmer

Question 20

Calving effect

Answer 20

• periparturient increase in the movement of the pedal bone

Question 21

How to prevent loss of fat from the digital cushion and new bone formation on P3

Answer 21

• minimise BCS loss to peak yield
• manage diets (esp of high yielding dairy cows) to: avoid subacute rumenal acidosis (SARA), providing a source of high quality long fibre, minimise BCS loss to peak yield
• identify and tx animals early to limit the impacts of dz - mobility scoring every 2w

Question 22

Risk factors of white line dz

Answer 22

• poor underfoot conditions/track conditions
• turning sharply, shearing forces
• periparturient increase in the movement of the pedal bone
• loss of fat from the digital cushion and new bone formation on P3

Question 23

Prevention of WLD - poor underfoot conditions/tracks

Answer 23

• improve cow tracks
• repair damaged yards
• gateways and water troughs
• forcing/pressurising cows forward -> increases lameness, prevents them watching and controlling their foot placement
• repair damaged concrete
• presence of FBs/stones

Question 24

The ideal track

Answer 24

• cushioned for comfort
• wide (3.5m)
• no sharp turns, steep sections or bottle necks
• quick drying and free draining
• free of sharp grit
• free of material that can trap between the claws
• good grip
• not overly abrasive
• cheap
• for cow use only (no vehicles)

Question 25

Prevention of WLD - turning sharply, shearing forces

Answer 25

- turning sharply or slipping on concrete may weaken the white line - remove: narrow doorways, bottle necks, blind alley (bullying), overcrowding - slipping: grooving concrete provides good foot purchase, 6-10mm deep, 10mm wide, 40mm between grooves

Question 26

Bullying

Answer 26

- linear hierarchy - dominance is mainly dependent on age (older=more dominant), size (larger=more dominant), weight (heavier=more dominant) - expressions of dominance and fighting are more common when: mixing groups, group sizes are large? cows compete for a limited resource

Question 27

Biotin (B7)

Answer 27

- 20mg/cow/day added to diet - can be included in concentrate at the mill of added separately to a total mixed ration - multiple studies have demonstrated a reduction in the incidence of WLD (approx 1/2 the risk) - high yielding cows fed high concentrate diets suffer subacute rumenal acidosis (SARA) -> this may lead to a reduction in B vitamin production, supplementation may be particularly important in these animals

Question 28

Healthy feet programme risk assessment tool guide

Answer 28

- low infection pressure: hygiene, biosecurity, foot bathing - good hoof shape, horn quality and digital cushion: genetics, nutrition, foot trimming, BCS, moisture - early detection, prompt effective treatment: equipment, training, mobility scoring, time management, trimming protocols - low forces on feet (good cow comfort, good cow flow): housing, heat stress, stockman ship, time budgets, floor surfaces, tracks