Exam 2 Flashcards
Lameness Exam
o Walk
o Slow steady trot
o 2-beat symmetrical gait
o increased stress and concussion
o Smooth, flat, hard surface
o Straight line and small circles
o Examine moving toward and away, as well as from the side
o May need to see during activity where lameness identified
Features of a Lameness Gait
o Consistent- pain every time the limb is used
o Regularly irregular
o Decreased stride length
o Decreased concussion
o Occurs the same every stride
o May seem inconsistent when only seen during specific activity, but should be consistent within that activity
Features of a Mechanical Gait
o Consistent
o Repeated every stride
o More irregular
o Less subtle gait alteration than a lameness gait
Features of a Neurologic Gait
o Inconsistent
o Irregularly irregular
o Foot flight, stride length, and concussion may vary with every stride
o Very common
o Easy to confuse with lameness
o Neurologic and lame
Signs of Forelimb Lameness
o Head nod
o Unequal concussion
(louder on sound limb)
o Shoulder drop
(lower when weight on sound leg)
o Decreased stride length
Define: Unequal Concussion, Head Nod, Fetlock Drop
Unequal Concussion
* Landing heavier on the sound leg
Head nod
* up when lame leg hits, down on the sound leg
Fetlock drop
* lower on the sound leg
* Shortened cranial phase of stride
Why Work in a Circle
o Used to exacerbate mild lameness
o Usually makes lameness of inside leg more noticeable
o Increased strain on lateral side of inside leg and medial side of outside leg
o If pain is equal on both limbs no head nod
Signs of Rear Limb Lameness
o More difficult to recognize
o Cannot tell source by how horse travels
o Unequal concussion
o Hip hike
up when lame leg hits ground
o Fetlock drop lower on sound leg
o Swinging leg in or out
o Shortened stride
o Head nod down on forelimb diagonal to lame hind limb
Nerve Blocks for Lameness Localization
o carbocaine(best), lidocaine, bupivicaine -> wait 10 mins
o Can start with any suspect joint
o If no clues-start distally and work your way up
o May need to perform additional blocks on another day
o Localizes lameness to a smaller area
Common Causes for Forelimb Vs Rear Limb Lameness
Common Forelimb Lameness
o Sore feet
o Navicular Syndrome/ Palmar Heel Pain
o Carpal or fetlock arthritis
o Tendinitis
o Suspensory desmitis
o OCD
Common Rear Limb Lameness
o Distal tarsitis
o OCD
o Suspensory desmitis
o Sore feet
What do these look like? Fibrotic Myopathy, Stringhalt, Shivers, Upward Fixation of Patella, Rupture Peroneus Tertius
Fibrotic myopathy
o Fibrous band of tissue
o Horse brings foot forward and then slaps down
Stringhalt
o Hyperflexion of one leg when walking
Shivers
o Spastic “shivering” when trying to backup
Upward fixation of patella
* Dragging toe
Ruptured peroneus tertius
* Floppy leg
* Can extend hock while flexing stifle
Objectives of Fracture First Aid
o Relieve stress, pain, and anxiety
o Preserve nerves and blood vessels
o Protect soft tissue and prevent bone penetration of the skin
o Prevent further damage to bones
o FIRST THING STABILIZE
Sedation for Fractures
Acepromazine:
* Limit use to only animals without signs of shock!
* mares and geldings to decrease ataxia of other sedatives
Butorphanol:
* Good analgesia, may cause excitement if given alone
Xylazine:
* predictable and safer in animal with shock
Detomidine:
* longer duration of action than Xylazine
What to do if Bone is coming out of skin on Fx
o CLEAN
o Clip?
o Cover in water soluble dressing & sterile bandage
Ideal Splint for Fracture
o Stabilize joint above & below
o Neutralize damaging forces
o Minimally cumbersome
o Easy to apply
o Does NOT require general anesthesia
o Economical/accessible
o PVC, oak boards, etc
o metal is not usually a good choice
Things to Remember about Fractures of the Phalanges & Distal Metacarpus
o Biomechanically dominated by the angle of the Metacarpal joint
o Principal bending focus becomes the fracture site rather than the joint
o Splint must include neutralizing both the bending forces of the Metacarpal joint as well as the fracture site
How to: Splint a Fracture of the Phalanges or Distal Metacarpus
o Don’t put joint in normal anatomical position
o Dorsal cortices of the bones should be aligned in a straight line ->
o Apply a light bandage (~1/2 inch thick) to the distal limb ->
o Tape splint (PVC or board) to dorsal aspect of distal limb from carpus to toe ->
o Splint should align dorsal cortices of bones & neutralize suspensory apparatus ->
o Apply cast material over splint
Important things to know about Fractures of the Mid-Forelimb
o medial aspect of the radius is not protected by muscle
o the skin is easily penetrated by a fracture and must be protected
Splint Fractures of the Mid-Forelimb
o Apply a Robert Jones from elbow to ground (3x diameter of limb)->
o Apply a lateral splint extended up the lateral side of the shoulder
o Tape securely to the proximal forelimb at the level of the axilla (prevents the distal limb from abducting)
Important things to know about Fractures Proximal to Cubital Joint
o Scapula, humerus and ulna are well protected by muscle -> stabilize the fracture and protect the skin
o disarms the triceps apparatus -> impossible for horse to fix elbow for weight bearing
o splint carpus in extension so horse can use limb for balance & ambulation
Important things to know about Fractures of the Mid & Proximal Metatarsus (Hind Limb)
o Splints are placed caudally and laterally over a Robert Jones bandage
o Robert Jones should be less extensive than on the forelimb to help keep the splints in place
o splints extend from the calcaneal tuber to the ground
Important things to know about Fractures of the Tarsus & Tibia (Hind Limb)
o Very difficult to adequately stabilize
o Reciprocal apparatus causes tarsus to flex and extend each time the stifle flexes and extends
o Stifle flexion causes fractures of the tibia or tarsus to override
o Splinting can minimize lower limb abduction-adduction and trauma
o Use Robert Jones with a single extended lateral splint that extends over the angle of the hock
o in proximal fractures splint should extend to the point of the hip
Important things to know about Fractures of the Humerus
o Do not need external stabilization
Antibiotics & Analgesia for fractures
Antibiotics for Open Fractures
o Penicillin + Gentocin
o Cefazolin + Gentocin
Analgesia For Fractures
o Phenylbutazone
o Butorphanol
o IM Detomidine
Transporting Horse w/ Fracture
o hay net may be best for keeping horse calm
o Space minimized to support the animal on all sides
o Forelimbs should be transported backwards
o Hindlimbs transported forward
o Head and neck should be left free or loosely tied for balance
Sequestrum; Pathophysiology, Clinical Signs, Diagnosis, Treatment
Pathophysiology
* Piece of dead bone that has become separated during the process of necrosis from the sound bone
* Most secondary to trauma and are infected
* Or develop secondary to vascular compromise of the cortex (periosteum)
Clinical Signs
* +/-lameness
* Localized heat and swelling
* Persistent drainage with tract
Diagnosis
* Radiographs at 12 days usually demonstrate separated bone
* Bone usually is not completely separated until 3 weeks
Treatment
* Surgical removal
* May be done standing in selected cases
* Fragment should be removed and the granulation bed débrided to healthy tissue
* +/- Antibiotics
Septic Arthritis/Tenosynovitis; Risk factors, Clinical Signs, Diagnosis
Risk Factors
* More common in foals w/ bacteremia/septicemia
* Standardbred
* Intra-articular injections
* Failure of passive transfer
* Systemic sepsis
Clinical Signs
* Lameness
* Transient fever
* Joint effusion
Diagnosis
* Arthrocentesis
* Usually >30,000 WBCs w/ 80% degenerative
* TP > 3
* gram stain slides
* culture
* rads for rule out & determine prognosis
Septic Arthritis/Tenosynovitis; Common Bacteria, Treatment, Prognosis
Common Bacteria
* E. coli
* Strep
* Staph (post injection or sx)
* Anaerobes
Treatment
* Broad spectrum antibiotics 2-3 wks post infection
* Joint lavage
* Hyaluronana IV or IA to reduce inflammation & DJD
Prognosis
* Better in adults than foals
Joint Lavage
o Indicated in ALL cases of septic arthritis
o Use needle, arthroscopy, or arthrotomy
o Sterile balanced electrolyte solution
When/How to Use Open Drainage of Joints
o chronic sepsis or cases that do not respond to joint lavage
o 3-5 cm arthrotomy incisions
->
o Drain into sterile bandage which is changed 1-2x daily
o When upper joints are involved cross tie to prevent contamination
Regional Perfusion of Antibiotics
o Maximize tissue penetration of antibiotic around joint
o Use 1g Gentamicin diluted to 30-60ml
o Place tourniquet above & maybe below target site ->
o Inject antibiotics into vein distal to site or into medullary cavity
Polymethylmethacrylated MOA
o Used to impregnate Antibiotic into tissue
o Antibiotic release is based on diffusion concentration gradients
Epiphyseal Osteomyelitis; Signalment, Pathophysiology, Diagnosis
o Part of the polyarthritis or polyosteomyelitis syndrome in young foals
o Usually <2mo old
Pathophysiology
* Pooling of blood in the venous sinusoid at the junction of the epiphyseal bone and cartilage ->
* Sluggish blood flow encourages bacteria to lodge and establish at this site
Diagnosis
* Septic arthritis of adjacent joint
* Arthrocentesis & culture
* Radiographs now and in 7 days
* CT shows early changes
* MRIs best
Golden Period
o Time it takes for bacteria to multiply 10^6 bacteria per gram of tissue
Factors that Favor Wound Infection
o Contamination with feces (10^11 bacteria per gram)
o Contamination with soil (as little as 100 microorganisms per gram)
o Virulence of offending bacteria
o Reduced local defense mechanisms due to damaged blood supply, foreign body presence, or necrotic tissue
Wound Lavage; What to use, figure out if the joint is involved
What to use
* balance between antimicrobial action and tissue cytotoxicity.
* 10ml Betadine 10% per liter of irrigation fluid = 0.1%
* 25ml Chlorahexidine 2% per 975 mL of irrigation fluid = 0.05%
* homemade saline = 8tsp salt/1gallon H2O or 10ml/L
* may use antibiotics but should use before closure
Is the joint involved?
* Do arthrocentesis
* Don’t go through contaminated wound
Proud Flesh; What is it? Pathophysiology, Treatment
o Wounds at or below carpus & tarsus
o Normal process due to lack of skin, motion, infection
o Must eliminate underlying issues
Pathophysiology
* Fibroblasts & endothelial cells + no nerves ->
* Needed as scaffold for epithelial migration ->
* Resistant to infection
Treatment
* Trim
* Topical corticosteroids
Management of Wounds at the Coffin Joint
- Stop bleeding
- Assess the ENTIRE horse
- Clean wound
- Local anesthesia
- Assess for synovial envolvement
- Bandage or cast
Extensor Tender Lacerations; Clinical Signs, Treatment
Clinical Signs
* Knuckiling
* Quickly learn to place correctly
Treatment
* Debride aggressively
* May need splint/cast/shoe if horse is knuckling
* Rarely suture extensor tendon
Repairing Comminution
o must have 6 cortices proximal and distal to fracture
o must have 180 degrees of cortices to carry weight
o P1 fractures must have an intact strut of bone spanning the fetlock and pastern joints for internal fixation
Placing Lag Screws
o Drill glide hole (outside diameter of the screw) near cortex ->
o Drill thread hole (core diameter of the screw) ->
o Counter sink ->
o Measure ->
o Tap (create threads in far cortex) ->
o Place and tighten screw
Locking Compression Plate
o Every screw = 1mm fracture compression (up to 4)
Open Fractures & Repair
o Reduce survival by 50%
Indirect Bone Healing
o Callus formation due to unstable mechanical environment caused by motion
Strain & Mechanisms to Decrease Strain
o Strain = ratio of change in gap width over total width of gap
o More change in gap -> less good healing
Mechanisms for reduction
* Fragment end resorption increases width of gap -> decreases ratio of change -> decreases strain
* Number of fracture lines decreases strain on any individual fracture line
* Sequential formation of stiffer tissues in the fracture gap
Worst Fractures for Healing
Displaced, comminuted fractures of the
* femur,
* humerus,
* proximal tibia
* proximal radius in adult horse
Options for Correcting Angular Limb Deformities
o Controlled Exercise (wind swept foals)
o Corrective Shoeing (lateral or medial bending)
o Cast Application
o Growth Acceleration
o Growth Retardation
o Deformity of bones
Names of Direction of Angular Limb Deformity
o ^ valgus
o v verus
Treatment Timing for Angular Limb Deformities
Fetlock
Medical – 4wks
Surgical – 2mo
Distal tibia
Medical – 4mo
Surgical – 4-6mo
Distal radius
Medical – 4-6mo
Surgical – 6mo
Periosteal Stripping
o Inverted T-shape in periosteum above physis
o Done on side hoping to accelerate growth
o Controversial
Options for Growth Retardation
o Both must be CAREFULLY monitored
Bridge
Screws above and below physis parallel to joint surface
Retards growth across physis on that side
Wire must get tight before change
Transphyseal
Screw bridging physis
Quicker than bridge
Congenital Hyperextension; What is it? Treatment
o Hyperextension of fetlock
o Laxity at flexors
Treatment
Exercise
Shoes
Cautious w/ bandaging (do not use rigid)
Congenital Contracted Tendons Treatment
- Analgesics
- Oxytetracycline IV (once hydrated!)
- Toe extension
- Splints/casts
- Surgery for flexor carpi ulnaris & ulnaris lateralis tendons
Distal interphalangeal joint contracture; What? Cause, Treatment
- Most common acquired Flexural Deformity
- Coloqually called club foot
Cause
* Contracture of the deep digital flexor tendon
Treatment
* Transection of the inferior check ligament (desmotomy)
* + concurrent & repeated trimming of hoof to lower the heel
Distal interphalangeal joint contracture; Medial Vs Lateral Approach
Medial
* Cosmetic
Lateral
* Easier
* Less wrap around of check ligament
* Can result in entrapment of medial palmer artery (bad)
Osteochondrosis; Signalment, Most Common Joints, Pathogenesis, Histo Lesions
Signalment
* 5-25% of horses affected
* Warmbloods, thoroughbreds, QHs
Most Common Joints
* Tarsocural
* Femoral patellar
* Metacarpalphalangeal
Pathogenesis
* Genetic predisposition +
* Too much dietary energy, high phosphorous, high zinc +
* Biomechanical overload ->
* Vascular compromise to nourishing vessels of epiphyseal cartilage ->
* Failure of ossification & retained growth cartilage ->
* Retained cartilage plugs die
Histilogic Lesions
* Persistent chondrocytes in mid-late hypertrophic zone
* Failure of vascular invasion
* Osteogenesis
OCD Lesions Vs Subchondral Bone Cysts
OCD
* Flap develops in areas of shear forces
Cysts
* Develop in areas of weight bearing
OCD of Tarsocrural Joint; Signalment, Location, Symptoms, Diagnosis, Treatment
Signalment
* All ages but mostly <3yo
Location
* Distal intermediate ridge of tibia > lateral trochlear ridge > medial malleolus
Symptoms
* Often present w/ synovial effusion
* Lameness rare
Diagnosis
* Rads of dorsomedial plantarolateral oblique (DMPLO)
Treatment
* Surgical removal if clinical
* May recover on own
Osteochondrosis of Femoropatellar Joint; Symptoms, Locations, Prognosis
Clinical Signs
* Lesions stabilize by 8mo old & show signs at 3yr old
* Often occur bilaterally
* Joint effusion
* Variable lameness
Common locations
* Lateral trochlear ridge
* Maybe medial trochlear & patella
Prognosis
* Dependent on extent of damage in trochlear groove
Subchondral Bone Cysts; Locations, Clinical Signs, Treatment
Locations
* Usually medial femoral condyle
* Maybe lateral condyle or proximal tibia
* Usually bilateral
Clinical Signs
* Detected once in training
* Can result from trauma
Treatment
* Sx debridement
* Injection of cyst w/ steroids
* Rest
* Transcondylar Screw across cyst (best)
Foot Abscess; Affected Area, Clinical Signs, Causes, Diagnosis
Area
Between sensitive & insensitive laminae
Clinical Signs
Warm
Increased digital pulses
Sensitive to hoof testers
Severe lameness
Acute onset
Causes
Sole bruising
Penetrating injury of foot
“hot nail” nail from shoe in wrong place
Migration of infection from white line
Diagnosis
May use nerve blocks
ID of abscess tract
Foot Abscess; Treatment
Create small hole to drain & follow tract to completion
DO NOT expose too much solar corium
If abscess won’t open yet
* Soak in warm water & Mg Sulfate
* Poultice of Epsom salt or Mg Sulfate
* Extensive sole resection & hospital plate
Once Open
* Flush tract w/ iodine ->
* Pack w/ small amount iodine soaked gauze ->
* Soak 1-2x/day for 2d
* Check tetanus status
* NSAIDs
Gravel; Pathophysiology, Clinical Signs, Diagnosis, Treatment
Pathophysiology
Similar to hoof abscess
Ascending infection from white line
Usually associated w/ previous pathology of white line
Clinical Signs
Swelling at coronary band
Lameness
Heat
Pain
Swelling
Drainage at coronary band
Diagnosis
Rads
Treatment
Debridement of hoof wall
Radical hoof wall resection
Laminitis; Pathophysiology, Signalment, Causes, Clinical Signs, Treatment
Pathophysiology
Inflammation or edema of sensitive lamellae ->
Breakdown & degeneration of union btwn horny & sensitive laminae ->
Rotation or sinking of P3
Often affects front > rear
Signalment
15% of adult horses affected at some point
Most result in euthanasia
Causes
Biomechanical
Ingestion of excess grain
Grazing of lush pasture
Excessive exercise/concussion in unfit horse
Endotoxemia
Systemic Dz
Clinical Signs
Increased digital pulses
Warm/cold feet
Stance: weight on hind w/ front extended
Treatment
Stall rest
NSAIDs, Opioids
Foam support p[ads
Ice boots
Corrective trimming/shoeing
May do DDF tenotomy but only helps some
Lamellar Anatomy
Surface areas = 1sq meter
Epidermal lamellae
* Avascular & aneural
Dermal Lamellae
* Very vascular & neural
Basement Membrane
* Tough sheet of connective tissue at the interface of the lamellar
* Receptor site for growth factors, cytokines, and adhesion molecules
Phases of Laminitis
Developmental
* 24-48hrs
* You may be able to intervene but rarely seen now
Acute
* First signs of hoof pain
Chronic
* Rotation or sinking of P3
Basics of Articular Cartilage
o Mostly water
o Other part is type II collagen > proteoglycan > minerals > chondrocytes/lipids
o Avascular, aneural, alymphatic
o Matrix maintenance and turnover regulated by chondrocytes (VERY slow)
Pathophysiology of DJD
Disruption of balance between degradation and synthesis of extracellular matrix ->
Breakdown of the collagen framework ->
Reduction in proteoglycan content and alteration of proteoglycan structure ->
Increased water content ->
Increased degradative enzyme activity ->
Articular cartilage becomes softer in compression and weaker in tension ->
DJD
Cartilage has very limited ability to heal
Extrinsic Repair of Articular Cartilage
Partial thickness defects -> rarely completely heal, may not compromise joint function
Full thickness defects -> repair by in growth of subchondral fibrous tissue -> not affective for normal use
Non weight bearing heals fast than weight bearing
Repair tissue is usually Type I collagen
Osteoarthritis; Clinical Signs, Rads, Treatment
Clinical Signs
o Heat
o Pain
o Lameness
o Effusion
o Crepitus
o Decreased range of motion
OA Rads
o Periarticular osteophyte formation
o Subchondral bone sclerosis
o Subchondral bone lysis
o Narrowing of the joint space
o Ankylosis
Treatment
o CANNOT REDUCE DAMAGE
o Surgery for prevention
o Adequan
o Hyaluronan
o Corticosteroids
Adequan for Joints
PSGAG
May alter progression of DJD
Used when extensive cartilage loss
Chondroprotective
Can prolong bleeding times & potentiate infection
Give IM or IA w/ Amikacin
Hyaluronan for Joints
Hyaluronic acid
Linear polysaccharide
May decrease lameness
Anti-inflammatory
May induce production of endogenous hyaluronic acid
Corticosteroids for OA; Use, Drugs, Adverse Effects
Use
* Used to treat various arthopathies
* Onset of action is immediate
Drugs
* Methylprednisolone Acetate (Depo)
* Triamcinolone Acetonide (causes laminitis?)
Adverse Effects
* High doses can damage cartilage matrix metabolism
* Steroid arthropathy
* Post injection flare
* Potentiation of infection
Palmer Heel Pain; Signalment, Clinical Signs, Affected Areas, Diagnosis
Signalment
o Small feet
o Underrun heels
o Long toes
o Often QHs
Clinical Signs
o Blocks out w/ palmer digital nerve block
o Bilateral
o Chronic
o Progressive forelimb lameness
Areas that can be affected
o Navicular bone
o Navicular bursa
o Coffin joint
o P2, P3
o Impar ligament
o Deep digital flexor tendon
Diagnosis
o Ultrasound
o CT (best value)
o MRI (best image)
Palmer Heel Pain; Treatment
Medical
Correct hoof imbalances w/ trimming and/or shoeing
Allow hoof expansion
Short-term raise angle of hoof w/ heel wedge
Phenylbutazone
Steroid injection in coffin joint or navicular bursa
Surgical
Palmer digital neurectomy (careful they may hurt themselves)
Navicular suspensory ligament desmotomy (out of favor)
Navicular bursoscopy
