Bovine Musculoskeletal Flashcards
What are the top 3 issues affecting dairy herds in the UK?
Lameness, mastitis and fertility
What is the impact of lameness on cow welfare?
Pain and discomfort
Susceptibility to other disease
Yields
Reproductive performance
Behavioural changes
What are the behavioural changes caused by lameness?
- Increased lying times – longer bouts
- Which can cause a reduced feed intake
- Suppression of oestrus expression
- Can cause reduced visits to robot in automatic milking systems
What are the direct costs of lameness in cows?
Treatment cost
Vet time
Farmer time
Milk discard
Decreased milk yield
What are the indirect costs of lameness in cows?
Increased risk of culling
Effects on fertility
Risk of further lameness cases
Risk of secondary disease
What is the best way to identify the prevalence of lameness in UK dairy herds?
Mobility scoring
What is the cost of lameness to the average UK dairy herd?
- If the average case costs £330 and the average case of lameness “lasts” 5 months
- So a lame cow costs £2.20 per day
- Average 200 cow herd with 25% lameness = £110 a day = £40,150 a year
Define the coronary band, wall and periople.
Coronary band – junction between skin and shorn, produced the wall horn
Wall – formed at a rate of 5mm/month, migrates down hoof
Periople – junction between skin and horn at coronary band , arms waxy coat to hoof
Define the sole, white line and heel.
Sole – formed for papillae on sole, wall and sole meet at white line
White line – join between wall and sole, point of weakness
Heel – soft sponge horn
Describe the position of the pedal bone/P3.
- Centrally within hoof, mainly attached to dorsal wall
- Flexor tendon attached to palmar/planter edge
- Navicular bone between tendon and P2
What is the function and position of the corium/stratum germinativum?
Produces horn
- Fills space between sole and P3, vulnerable to pinching
- Blood vessels, nerves and other support structures - very sensitive
If the digital cushion is made from fat and connective tissue in which animals may the digital cushion be less effective?
Old and thin cows and heifers
Describe the structure of the laminae in the bovine foot.
- Junction between the wall and P3
- Sensitive dermal laminae from P3
- Insensitive epidermal laminae from hoof wall
- Interdigitate like interlacing fingers
- Suspends P3 within the hoof capsule
- Affected by hormonal changes around calving
What is the normal size of the hoof?
Anterior wall – 80mm (60-90mm)
Anterior wall to ground – 45-50˚
Heel height – 25-35mm in young, 30-45mm in old
Why does it take time for the horn of the bovine foot to repair?
Slow growth rates – approximately 5mm per month
What is hoof growth rate affected by?
- Loading - increased loading = increased growth)
- Claw - outside > inside on the hind feet
- Nutrition
- Age
- Breed
Where do wall and sole growth originate?
Wall growth – starts from the coronary band, downwards to the toe
Sole growth – starts from the sole corium (quick), downwards and forwards
What are the cow factors of horn wear?
Horn quality
Hoof conformation
Limb conformation
Udder size and structure
What are the external factors of horn wear?
Underfoot conditions – surface abrasiveness, slurry dept
Management factors – walking distances, foot trimming, housing programme
What are the factors affecting horn quality?
- Lameness
- Damage to the corium or coronary band
- Underfoot conditions
- Foot bathing
- Systemic illness (hardship lines)
- Nutrition – low biotin or high concentrates
- Breed and age
Describe normal weight bearing on the hoof.
Should have weight bearing around the outside of the foot, around the outside of the foot and onto the heel, shouldn’t be any on the sole so shouldn’t have any pinching.
Describe normal weight bearing of the limbs and claws.
Forelimbs – 60% bodyweight, more on inside claw, larger inside claw
Hindlimbs – 40% bodyweight, more carried on outside claw, large outside claw
Where is somewhere you don’t really get overgrowth on the bovine foot?
Heels
What is the result of toe overgrowth?
- The wall is worn more rapidly at the heel, heel undermined by slurry heel in winter
- Further overgrowth at toe = NWB
- Shifts weight further back (45˚)
- Sole corium pinched, pain whilst walking
- Sole bruising/haemorrhage causes inflammation and sole ulceration
What is the result of sole overgrowth?
Overgrowth at the toe leads to thickening of the sole
What may cause the disparity in claw size when weight bearing on the lateral hind claw?
- Irritation and sole overgrowth
- Increased pressure and pain in lateral claw
- Abduction of the limb
- Increased weight on medial claw, decreased wear on lateral claw
- Overgrowth at toe forces hocks together
- Decreased weight bearing on lateral claw
If a cow is walking on an overgrown claw, what structure is at risk of being damaged?
Corium
What is the aetiology of septic arthritis in calves?
Tertiary spread of infection, umbilicus or generalised bacteraemia - T. pyogenes, E. coli, Strep. spp., Staph. spp. and Salmonella
What are the clinical signs of septic arthritis in calves?
Lameness followed by joint heat, pain and swelling
How is septic arthritis in calves usually diagnosed?
Presenting signs
Differentiated from other joint pathologies, such as intra-articular fractures
How is septic arthritis uncommonly diagnosed in calves?
For unresponsive cases or where worried about AMR:
- Arthrocentesis – large volumes of turbid, clotted fluid containing large amounts of protein and many PMN’s
- Aseptic samples for culture
How is septic arthritis in calves treated?
- 2 weeks of broad spectrum parenteral antibiotics – amoxicillin, oxytetracycline
- NSAIDs
- Less commonly - open joint lavage, best prognosis if performed in acute stage
What is the prognosis of untreated septic arthritis in calves?
Severe joint damage
How is septic arthritis in calves prevented?
Good calving hygiene and application of topical naval dressing
What is the occurrence and cause of septic arthritis in older animals?
Uncommon. Similar to joint ill, often penetrating injury
What is the aetiology of hip dislocation?
- Usually seen in adult cows after traumatic abduction (“partial splits”) of hind legs
- Soon after calving, when relaxation of ligaments maximal
- Femoral head displaced craniodorsally in most cases
What are the clinical signs and presentation of hip dislocation?
- Down cows – with history of recent calving/seeing slipping
- Acute onset lameness, usually non weight bearing
- Craniodorsal dislocation – the pelvis and hips will often appear asymmetrical if viewed from behind
How are hip dislocations diagnosed?
Manipulation of leg, which can be difficult with large muscle mass = restriction movement and crepitus
Usual triangle of the pelvis can become much reduced and hip pops out, moving cranially and dorsally
How is hip dislocation treated?
Depends on size/weight of animal and how soon after dislocation we see them:
- Euthanasia if non-reducible (majority of cases)
- Replaced by manipulation (if small/light weight)
How are hip dislocations replaced by manipulation?
- Soon after dislocation
- Heavily sedated (xylazine)
- Forcible replaced by combination of rotation to loosen the soft tissue contraction, leverage and pressure on the femoral head
What is the prognosis of hip dislocations?
Good provided cases are uncomplicated (no fractures) and replacement attempted early
Poor if dislocated for a while
Name 2 aetiological agents of mycoplasma arthritis. What do each cause?
Mycoplasma bovis – arthritis
Mycoplasma wenyonii – hind limb oedema
What is the pathogenesis of mycoplasma bovis arthritis?
- Cow to cow spread – close and repeated contact over short distances
- Asymptomatic carriers?
- Mastitis, calf respiratory disease
What is the pathogenesis of mycoplasma wenyonii arthritis?
- Blood borne
- Spread in herd vaccination?
- Udder oedema, lymphadenopathy, pyrexia
What are the clinical signs and presentation of mycoplasma arthritis?
- Severe arthritis in calves and adult cattle
- Severe lameness
- With/without one or more swollen lower limb joints in which damage rapidly occurs
- In conjunction with mastitis?
How is mycoplasma arthritis diagnosed?
- Antibody tests
- Culture?
- PCR
- Based on signs if known to be present in a herd
How is mycoplasma arthritis treated?
Oxytetracycline or tylosin
Name 4 rare bone and joint diseases that can affect cows.
Hip dysplasia
Osteomyelitis
Patellar luxation
Generative joint disease
Describe hip dysplasia in cows.
Gradual onset hindlimb lameness in growing animal 4-12 months
Describe osteomyelitis in cows.
Uni or multifocal, possible salmonella related in calves, penetrating trauma in adults
Distinguish dorsal and medial/lateral patellar luxation in cows.
Dorsal – sporadic, mature cattle. Leg held out stiff/behind, suddenly snaps forward in jerky action, may be intermittent
Medial or lateral – rare, congenital. Stifle collapses when weight borne, unilateral or bilateral may be secondary to femoral nerve paralysis
What are the most common causes of bovine lameness in the foot?
Sole ulcers
White line disease
Local sole bruising
Digital dermatitis
Foul in the foot
What structure protects the corium from pinching by P3?
The digital cushion
What is the aetiology of sole ulcers?
- Happening inside the foot that has worked its way out – insult takes a while to be seen as it grows from the corium
- Disruption of claw horn formation
- Weight of cow borne through suspension of P3 in hoof capsule. Relaxation of supporting structures around calving, which allows this caudal movement of P3
- Compounded by standing on concrete, thin cows (= thin digital cushion), poor conformation/insufficient routine foot trimming
- Pinching
What causes pinching of the corium between P3 and sole?
- Hoof overgrowth
- Underdeveloped digital cushion in heifers
- Standing on hard surfaces
- Relaxation of support for P3 around calving
- Shape of P3
What is the result of pinching between P3 and the sole?
Degeneration of corium in coriosis > poor quality horn production and cessation of horn production
Sole haemorrhage
Distinguish mild and sever sole ulcers.
Mild sole ulcers = incorporation of blood into horn = sole haemorrhage
Severe (standard) sole ulcers = horn production completely arrested = sole ulcer
What are the clinical signs of sole ulcers?
- Lameness
- Haemorrhagic discolouration means complete cessation of horn production at sole ulcer site
- Lateral claw of hind feet, medial claw of fore feet
- Possible secondary infection
- Deep digital sepsis in extreme cases
How are sole ulcers treated?
- Decrease pressure on pinched corium
- Corrective trimming and decrease height of affected claw and dish
- Remove underrun
- Foot blocks
- NSAIDs
What is the prognosis of sole ulcers that are not simple horn overgrowth?
Chronic coriosis may require regular corrective trimming. Deep digital sepsis, chronic bony changes
How are sole ulcers and coriosis prevented?
- Regular foot trimming to prevent overgrowth
- Good underfoot conditions
- Avoid standing times – rubber mats, turn them out
- Nutrition and BCS (thin cows go lame)
What is the aetiology of white line disease?
- Junction of sole and wall = area of weakness
- Dirt and stones impact causing infection carried through to corium
- White line seals over meaning infection is trapped
- Pus is produced and expands within potential space causing pain
- Abscess may progress – usually under running the sole, occasionally up the wall. Eventually pus breaks out, usually at heel or coronary band
What are the clinical signs of white line disease?
- Lameness
- Lateral claw more commonly affected
- Swelling – advanced with/without large abscess
- Leg abducted to bear weight on medial claw
How is white line disease diagnosed?
- Impaction and abscess if trimmed and explored
- Black holes
- Pain if “tweak” claw with hoof testers
How is white line disease treated?
- Trim and balance both claws
- Explore impacted white line, drain abscess, remove under run sole (at least enough to prevent re impaction)
- Foot blocks
- Parenteral antibiotics if necrotic corium
- NSAID
How long are blocks left on and why?
Wouldn’t leave block on for longer than a month so that not too much weight and pinching is put through the claw with the block on it
When are white line disease lesions harder to treat?
Tracks up wall
Deep digital sepsis
How is white line disease prevented?
- Underfoot condition – sharp stones, rough concrete, not being bathed in slurry that would cause feet to not be hard enough
- Avoid walking long distances on hard surfaces or rough tracks
- Biotin in the diet – hardens the white line
What is the aetiology of digital dermatitis?
- Spirochete bacteria
- Likely deep tissue invasion
- Spreads in contaminated slurry/water
- Fomite spread e.g. knives
- Subclinical carrier status
What are the clinical signs of digital dermatitis?
- Interdigital area behind heel bulbs
- Small circular (1-4 cm), moist browny grey exudative areas of epidermal liquefaction and matting of the surrounding hair
- Raw dermal granulation tissue if diphtheritic debris cleaned – intensely painful
- “Papilliform” form – long thick strands of keratin protrude from the underlying granulation bed
- Variable lameness
How is digital dermatitis treated on an individual level?
- Clean – anaerobic bacteria so cleaning and exposing to air will often cure
- Topic antibiotic – oxytetracycline sprays, soluble powders such as lincospectin, tylan?
- Topical non-antibiotic – copper/zinc containing gels
- Systemic antibiotics
How is digital dermatitis treated at herd level?
- Ensure feet are clean first
- Treatment bath
- Antibiotics not representative of good AM use
What is the prognosis of digital dermatitis?
- Good
- Front of foot causes damage to periople, which impairs production of wall, causing under running and vertical wall cracks
- Herd immunity seems to develop over time
- Herd eradication unlikely
How is digital dermatitis prevented?
- Improve housing hygiene with increased scraping
- Hygiene of foot trimming equipment
- Foot bathing
- Disinfectant
- Quarantine of new stock
What is the effect of involvement of non-healing sole ulcers and white line lesions?
- Acute onset, severe claw lesions
- Stippled appearance
- Seen in herds with DD presence
- Difficult and unrewarding to treat
- Can result in digit amputation
What is the aetiology of foul in the foot/foul interdigital necrobacillosis?
- Acute necrotising inflammation of interdigital skin
- Fusobacterium necrophorum +/- Secondaries (T. pyogenes, Streptococcus spp.)
- Damage to skin – FB’s, rough underfoot condition
What are the clinical signs of foul interdigital necrobacillosis?
- Sudden onset moderate to severe lameness
- Swelling of soft tissues above and around the coronary band and between the digits - forced apart
- Swollen, hot, inflamed and painful to the touch
- “Split” which discharges pus and lumps of necrotic tissue
- Swelling may track higher up the leg as infection invades
How is foul interdigital necrobacillosis treated?
- Check interdigital space for FB’s
- NSAID
- Parenteral antibiotics – milking/beef, cost/withdrawal
What antibiotic would be appropriate to choose to treat Fusobacterium necrophorum (and others)?
Amoxicillin and oxytetracycline – gram negative
How is foul interdigital necrobacillosis prevented?
- Improve underfoot conditions – increased mucking out
- Formalin foot baths