Locomotor Flashcards
Clinical exam
Observation from a distance
Symmetry, posture, conformation (poor conformation doesn’t necessarily mean lameness)
Significant variations are usually obvious
Clinical exam
Gait observation
Patient moving away, towards and across you
Possibility of circling and turning to exaggerate abnormalities
Which limb? Characterise and score problem
Clinical Exam
Manipulation of joints
Moving the joint and limb in a controlled fashion to determine:
- Range of movement/abnormal movement
- Pain related to movement
- Load or unload specific structures in the limb
Safety factor
Maximum stress a structure withstand until breakage
OVER
Stress it is most likely to undergo during its lifetime
Factors of failure
Force/stress: magnitude, frequency, speed of loading, duration of loading
Influenced by: body mass, speed, gait
Constraints during locomotion
Need to support against gravity, force only produced when limb in contact with ground
Increase in speed - shorter stance, higher force
Ligaments in equine distal limb
Superficial digital flexor tendon SDFT
Deep digital flexor tendon DDFT
Distal accessory ligament DAL
Suspensory ligament SL
Flexor tendon muscles
Highly pennate
Muscle fibres about 1cm
Limited capacity for length change
Tendons
7% energy release as heat (horses)
Gallop tendons about 45 degrees C
Kills some cells but not tendon cells
Predilection for tendon core injuries
Joints - function
Relative movement of limb segments
Shock absorbers
Joints - horse
Reduction of phalanges, fusion of bones -> movement in sagittal plane only Interlocking configuration (ridges/grooves) - collateral ligaments -> restriction of movement without muscular control -> decrease in metabolic cost
Hoof (equine)
Horn capsule - protection but no expansion
Mechanical function - shock absorption, support and grip, propulsion
Constraints - resistance to abrasion, protection of senstive structures
Hoof (equine) - protective mechanisms
Shape of solar surface allows heel movement
Suspension of distal phalanx: forces transferred via distal border of hoof wall
Digital cushion: shock absorption and frog movement
Hoof sliding
Rotation and translation of the DIP joint
Duty factor
Ratio of stance and stride time
All stance phases critical to injury
1st impact: large accelerations, low forces
- likely to result in bruising to the soft tissues
- ‘vibrations’ good for bones??
2nd impact: low acceleration, high forces
- important to allow for a natural braking action
Support: large vertical force
- up to 2.5x body weight per limb
- excessive dorsiflexion of the fetlock means tendon stress
Force usually acts parallel to the long bones
Very tight safety factors in equine limb
High speed exercise
Increase tendon strain:
- reduced fatigue life
- potent stimulus for changes in structural properties
Trade off:
- providing stimulus and exceeding the mechanical capacity
- estimated fatigue life of around 10,000 cycles
Shifting of the PZM (point of zero movement)
Increase of moment around DIP
Increase in stress by the DDFT on navicular bone
Compensatory decrease in fetlock extension - unloading of the DDFT
Hindlimb: also point of force laterally in late stance -> shortening of moment arm around DIP
Mediolateral imbalance
Mediolateral wedge (6mm wide) moves PZM towards elevated side of the foot
Lateral extensions, trailer shoes in bone spavin:
- horses attempt to unload the dorsomedial aspect of small tarsal joints by redistributing weight to plantarolateral aspect of the foot
Assumed mechanism: redistribution of weight by rotating the foot or by helping the horse weight-bear on the lateral side of the foot
Alternate explanation: horse forced to move ‘normally,’ no unloading of painful tissues - eliciting the repair process
Heel wedges
Move PZM towards the heels
Reduce DIP moment arm, unloading DDFT and navicular bone (NB)
Give longer support through stance
Increase DIP joint pressure
Shift articular contact area dorsally
Increase in pressure may directly result in pain, can cause damage by changing vascularisation to the synovium and cartilage function triggering a cascade of detrimental pathways
Collapsed/underrun heels
Tubules start bending when grown distal to the distal phalanx
Impairment of natural hoof deformation and blood flow
Application of carbon fibre patches beneficial
Cow Lameness
History questions
Which lactation? How long calved? Previous (foot) problems? How long has she been lame? Treatment? Is she pregnant? Is she milking?
Cow Lameness
Score 0
Walks with even weight bearing and rhythm on all four feet with a flat back
Long fluid strides possible
Cow Lameness
Score 1
Steps uneven (rhythm or weigh bearing) or stride shortened affected limb(s) not identifiable immediately
Cow Lameness
Score 2
Uneven weight bearing on a limb that is immediately identifiable and/or obviously shortened strides (usually with an arch to the centre of the back)
Cow lameness
Score 3
Unable to walk as fast as a brisk human pace
Cannot keep up with healthy herd
Dutch 5 step foot trimming
1 Create a foot angle of 52 degrees 2 Create balance between claws 3 Transfer weight from sole on to the wall, toe and heel 4 Remove weight from painful claw 5 Remove loose or sharp horn
Examination of lame foot - cow
Visible lesions on sole, wall, heel and skin
Heat
Pain with hoof testers and finger pressure on soft tissues
Feel and look between claws
Softening above coronary band or in heel
Redness (skin)
Smell
Sole ulcers
Treat early - how early?
Dutch 5 step method
Antibacterial treatment
NSAIDs
Nursing and clean yard
Promote wound healing - nothing that cauterises
Prognosis - generally ok, recurrence next lactation, reduced fertility and life span in herd, milk should recover in several weeks
Effective herd interventions - sole ulcers
Increase straw bedding to 1 bale/10 cows/d in cubicles
Heifer comfort group 16 weeks vs cubicles
White line - treatment
Drain pus, pare out to allow good drainage, cut away dead horn (can be done 2 weeks later), apply a block, NSAIDs especially if local swelling of corium, apply antibacterial product
Generally good prognosis unless infected with Treponemes
White line presentation
Diseased horn affecting the junction between the sole and wall, including bruising (haemorrhage), separation (fissure), abscessation and ulceration
These are generally considered to be stages of a disease process
The last stage - wall ulcer - is usually recorded separately due to the severe and chronic pain associated with it
Digital dermatitis - treatment
M1: clean, dry (paper towel), topical oxytetracycline spray (3d)
M2: as above but debride with gauze/paper towel ad consider bandaging with antibacterial agent
M3 and M4: clean, debride/debulk (under local as necessary) bandage with antibacterial agent
Herd: Footbathing, Slurry management, Biosecurity
Foul (in-the-foot)
An acute bacterial infection of the SC tissues characterised by symmetrical swelling, separation of the claws and interdigital skin necrosis yielding pungent odour
Often associated with FB or sand between the claws
Super foul is a severe per-acute form, possibly involving mixed bacterial infections
Clean/debride interdigital space
Disinfect
Licensed inj antibiotic
Corkscrew claw
Bony swelling deep to abaxial coronary band is diagnostic
Not to be confused with gross claw overgrowth
Reshape foot as best as possible
Claw amputation
Parenteral antibiotics
NSAIDs and IVRA
Prep
Incise into interdigital space - 2-3cm, skin fold
Embryotomy wire - out then obliquely upwards
Curette and remove any excess tissue
Melolin and pressure dressing
Redress at 48 hour, 96 hour, 7d then leave open
Block on unaffected digit
Arthritis in piglets
Rare in outdoor pigs
Sporadic opportunist infection in individuals - strep, staph, E.coli - through wounds (tail, teeth, skin wounds, navel)
Group outbreaks - Strep suis type 14 via tonsils
2d - weaning
Can’t stand, dog sitting, enlarged joints, death
Diagnosis: Bacteriology
Treatment: penicillin, ampicillin, lincomycin, ketoprofen, or euthanasia
Lameness in growers - pigs
Injury - fractures, osteochondrosis dessicans, pantothenic acid def. (rare), Ionophore toxicity (rare)
Infectious:
- Mycoplasma hyosynoviae
- Mycoplasma hyopneumonia or hyorhinis polyarthritis (and pneumonia)
- Erysipelas (zoonosis, note skin lesions)
Diagnosis: history, exam, PM, paired serology
Treatment for infectious: tiamulin, tylosin, lincomysin
Lameness in adult pigs
30% sow culls due to lameness
Physical lameness:
- Cartilaginous pathology (osteochondrosis, osteochondritis, dyschondroplasia or degenerative joint disease (DJD))
- Bony path leading to weakness and fracture (osteomalacia)
Infectious arthritis:
- Erysipelas, Mycoplasma spp.
Septic laminitis: bush foot due to bacterial infection - lincomycin, NSAIDs
Scald - sheep
(70%)
Primarily caused by Fusobacterium necrophorum - in faeces
Can progress to foot-rot
Foot-rot - sheep
(30%) Dichelobacter nodosus - Present on 90% of farms - Lives for 7-10d on pasture - Lives up to 6 weeks in hoof trimmings - Infected sheep = reservoir
CODD - sheep
(25%)
Caused by Treponemes
Treatment of footrot
Oxytetracycline spray a clean foot Long acting parenteral antibiotics (Oxytetracycline, amoxicillin) Allow sheep to stand on clean concrete Ideally isolate sheep 14d Prognosis: 90% recover in 5d Scald treatment v similar
Foot bathing - sheep
Use chemicals at correct concentrations:
- 10% zinc sulphate - stand sheep for >2min
- 3% Formulin
Stand sheep for 1 hr after and then turn in field for >14d of rest
Footbvax - sheep
Vaccinate before high risk periods (usually Autumn/Spring)
Primary - twice, 6wks apart
Boost 6 monthly
Include all sheep (and rams)
Contagious ovine digital dermatitis (CODD)
Same treponemes as bovine digi
Use Tilmicosin
Footbath with lincomysin or tylosin
What is laminitis?
Failure of the attachment of the epidermal cells to the epidermal (insensitive) laminae to the underlying basement membrane of the dermal (sensitive) laminae
May occur following a failure of epithelial adhesion molecules (hemidesmosomes) which attach the epidermal cells to the basement membrane
Dysregulation of cell adhesion is most likely caused by inflammatory and/or hypoxic cellular injury
Laminitis: risk factors
Can arise in association with disease characterised by sepsis and systemic inflammation (GS disease, pneumonia and septic metritis), endocrine disorders, mechanical overload, access to pasture (can be predisposed individuals)
- Pony vs horse
- Spring and Summer
- Female
- Older
- Obesity
- Recent increase in body weight
- Recent new access to grass
- Increasing time since worming and insulin resistance
3 stages of laminitis
Developmental: contact with trigger, last about 72h, damage occurs but no clinical signs, can’t see it (may suspect)
Acute laminitis: clinical signs
Resolution or chronic laminitis: depends on diagnosis speed, treatment and response
Inflammation and laminitis
It is thought that a systemic inflammatory response that accompanies hindgut carbohydrate overload somehow initiates lamellar inflammatory response
Vascular and endothelial dysfunction - laminitis
Early stages: vascular events include digital venoconstriction and consequent laminar oedema
Venoconstriction may be caused by platelet activation and platelet-neutrophil activation resulting in the release of the vasoactive mediator 5-HT
Amines from hindgut fermentation of CHO are vasoactive
Laminitis - diagnosis
Clinical signs +/- radiography +/- endocrine tests
Clinical signs: lameness affecting two or more limbs, characteristic stance of leaning back on heels, bounding digital pulses, increased hoof wall temp, pain on hoof tester pressure of the region of the frog, palpable depression at the coronary band
Laminitis - radiographs
If concerned that P3 moved
Can be difficult is painful - nerve block, take xray machine to horses
Latero-medial xrays of feet following good foot prep - need to markers on the feet inc one on the dorsal hoof wall, starting at coronary band and one at the point of the frog
Can assess pedal bone rotation and founder distance (sinking)
Laminitis - endocrine tests
Basal ACTH
Dex suppression (not Autumn)
TRH stimulation test
Laminitis - treatment
Medical emergency
Analgesia:
- NSAIDs, such as PBZ, flunixin, carprofen etc IV/oral
- Opiates - morphine, pethadine, fentanyl (hospital)
Foot support:
- Increase bedding esp at front of stable
- Bed rest
- Frog support - bandages, lilypads, NFS etc.
- Frog and sole support - caudal 2/3
Vasoconstriction?? ACP/ice
Change diet - no grass, 1.5-2% poor quality hay, no or minimal concentrates
Prognosis of laminitis
After 8 weeks - 95% alive
Depression extending round the whole coronary band suggests sinker = 20% survival
Evidence of previous attacks = success rate decreased by 20%
Rotation >11.5 degrees = prognosis sig reduced
Founder distance >15mm = 40% chance of return to soundness
Prevention of laminitis
Number 1 priority for pasture associated laminitis - overconsumption NSC (fructan + starch + sugar) - lower in growing plants.
Pasture should be managed to encourage growth
Diet should be based on forage/fibre, not sugar/starch
Extra energy can be added with oil or unmollassed beet pulp
Various supplements recommended
Osteomyelitis
Infection of the cortical bone and medullary cavity
Technically means all three layers are affected
Osteitis
Inflammation of the cortex without involvement of the red or yellow bone marrow
Septic or aseptic
Osteomyelitis - acute
Single limb lameness, rapid onset, short duration
Often history of laceration or surgery
Clinical exam: heat, pain, swelling on palpation of bones, joint structure may be normal, febrile
Plan:
- Sedation and analgesia, flush, broad spectrum antibiotics (endomycin and tetracyclins penetrate bone well), swab, bandage
Osteomyelitis - chronic
Moderate? Intermittant? Lameness of days/weeks duration Often history of laceration or surgery Clinical exam: - Possibly heat, pain, swelling on palpation - Joint structures may be normal - Pain, discharge, sinus tract formation - Pathological fracture - becomes acute Radiography important
Bone biopsy
Jamshidi needle (like a corer) or Michelle trephine (rarely used)
Through centre of lesion, both cortex and medulla sampled
Multiple samples through same skin incision
Cytology and culture
Osteosarcome treatment options
Amputation (4 months) - doesn't treat metastases Amputation and chemo (12-14 months) Limb sparing and chemo (12-14 months) Radiotherapy (palliative only) NSAIDs/Biphosphonates (palliative only) Euthanasia (common)
Calcium deficient animal
Essential for neuro-muscular function
Serum levels highly protected
Ca10(PO4)6(OH)2 robbed to protect serum calcium
Secondary nutritional
Hyperparathyroidism
Low dietary calcium drive high PTH levels Serum calcium is often protected Bones are malformed or poorly formed Normally a problem in growing animal Usually in exotics
Secondary renal
Hyperparathyroidism
Chronic renal failure (normally adult) Decreased activation of vitamin D Lowered phosphate excretion - Phosphate binds to calcium - Serum calcium is lowered Increased PTH drive and effects on bones (soft jaw)
Metabolic bone disease of reptiles and chelonians
Low dietary availability of calcium
Decreased activation or availability of vitamin D
Esp green iguana
Diagnosis:
- Lethargy, Movement/lameness (joint swelling, limb swelling, muscular tone and atrophy)
- Radiography: joints, limbs and spine, egg binding, spontaneous fractures, swollen bones poor density, misshapen, often pliant mandibles
- Blood sample: low Ca
Treatment: Ca gluconate, dietary adjustment (2% Ca diet), UV light and/or direct sunlight - not through glass, Monitor blood Ca
Equine Rhabdomyolysis Syndrome
Muscle cramping/pain that occurs usually during or following exercise
Also called: Monday morning disease, set-fast, azoluria, myoglobinuria, tying-up
Rhabdomyolysis - lysis of muscle fibres
Clinical signs: stiff movements, pain, sweating, tachycardia, myoglobinuria, plasma CK and AST activities
Treatment of acute exertional rhabdomyolysis
Analgesics (NSAIDs, opiates)
IV or oral fluids
Diuretics - fluids and diuretics are used to maintain urine output in attempts to prevent or minimise the nephrotoxic effects of myoglobin