Equine MSK diseases Flashcards
1
Q
List the causes of equine synovial sepsis in adults
A
- Trauma
- Post injection
- Post-surgery
- Idiopathic
2
Q
What is the most common cause of synovial sepsis in foals?
A
- Haematogenous spread of infection
- Septicaemia next most common cause
3
Q
What are the most common pathogens identified in equine synovial sepsis?
A
- Aerobic or facultative anaerobes
- E. coli, Streps, Staphs
- If traumatic, often mixed infection including Clostridia
4
Q
How may trauma lead to synovial sepsis in the horse?
A
- Direct inoculation of the joint
- Abscess erosion into joint after initial injury
- Osteomyelitis
5
Q
What condition would the following findings be indicative of in a horse?
A
- Warm joint
- Joint effusion
- Localised oedema/cellulitis
- Pain on palpation and flexion
- Marked lameness
6
Q
Describe the appearance of an open joint with synovial sepsis in horses
A
- Active discharge of synovial fluid from wound
- Viscous synovial fluid initially, the becomes more watery
- Lameness less severe vs. closed
7
Q
Describe the appearance of a closed joint with synovial sepsis in horses
A
- Usually penetrating injury with original entry wound sealed
- No discharge of synovial fluid
- Joint distension and pressure
- Removal of fluid allows alleviation of distension and lameness
8
Q
Outline the method for synoviocentesis in horses
A
- In field or hospital
- Must be aseptic: clip, surgical scrub (>3min contact time for chlor-hex or pov-io), sterile equipment, sterile gloves, no touch technique
- Sedate horse
- Enter away from wounds/cellulitis/dermatitis/source of infection
- Large bore needle
- Leave in place for further tests/adminisitration of antibiotics
9
Q
What is a potential complication for synoviocentesis in chronic wounds in horses?
A
Cellulitis may be extensive, preventing access to joint
10
Q
In which cases is synovial proliferation most likely to occur in horses?
A
- Fetlock proximal pouches, tarsocrural joints
- Chronic synovitis
- Chronic infection
- Open joints where most of fluid has drained
11
Q
What should be used to collect the synovial fluid from synoviocentesis in a horse?
A
EDTA, +/- culture bottle
12
Q
Outline how synovial proliferation can be overcome in order to obtain a sample from synoviocentesis in a horse
A
- Gentle aspiration and infusion of air to move synovial fronds from end of needle
- Go for most dependent/distended point
- Avoid areas of synovial proliferation
- Infuse small amounts of saline and re-aspirate (will alter all parameters)
13
Q
What would the following joint fluid analysis results suggest in a horse?
- Yellow, turbid appearance
- Total protein 46g/l
- Watery viscosity
- WBC: 57x10^9/L, 91% neutrophils
- pH 7.0
A
- Synovial sepsis
- Normals: clear/slightly yellow, clear
- Total protein 10-20g, infected >40g/l
- Viscosity: form 2.5-5cm string from fingers, 5-7cm string from syringe
- WBC count: 0.2x10^9/l, <10% neutrophils, some lymphocytes and mononuclear cells
14
Q
How can it be determined whether or not a wound is communicating with the joint space in horses?
A
- Inject 50-200ml of sterile isotonic electrolyte solution
- If joint not involved, should achieve moderate degree of distension
- Move horse a few steps so joint is flexed and extended
15
Q
What should be done prior to removing a needle following synoviocentesis in horses?
A
- Drain excess fluid and administer intra-articular antibiotics
- Even if is to go under GA and flush, will make horse more comfortable and improve chance off recovery
16
Q
When is radiogrpahy indicated in the investigation of synovial sepsis in horses?
A
- Where there is a chance of osteomyelitis (all foals) - Any causes of blunt trauma - Possibility of fracture - Foreign body
17
Q
If radiography is performed prior to synoviocentesis, what does gas in the joint capsule indicate in horses?
A
Open joint
18
Q
Outline the role of ultrasonography in the investigation of synovial sepsis in horses
A
- Identify radiolucent foreign bodies
- Soft tissue damage e.g. SDFT in plantar calcaneal injuries, DDFT in medial hock and tarsal sheath injuries
19
Q
What are the principles of synovial sepsis treatment in horses?
A
- Must be ASAP and aggressive
- Systemic and intra-articular antibiotics
- Joint lavage and drainage
20
Q
What are the options for lavage in a case f synovial sepsis of a horse?
A
- Through and through lavage
- Arthroscopic lavage
- Repeated open lavage and drainage
21
Q
Outline the aspects that must be ensured when performing through and through lavage for a case of synovial sepsis in a horse
A
- Large vols. of fluid (3-5L for small joints, 5-10L for large joints)
- Ensure joint distended and flushed (finger over needle end or close flushing catheters to prevent premature drainage)
- Multiple portals and rotate for lavage and drainage
- Adminster fluids under pressure
- Ensure wound is explored, flushed and debrided
22
Q
What portals should be used for through and through lavage of a tarsocrural joint in synovial sepsis in a horse?
A
- Dorsomedial
- Dorsolateral
- Plantaromedial
- Plantarolateral
- Move ingress through all of these
23
Q
When if through and through lavage for synovial sepsis not a good option?
A
- Chronic or concurrent infection
- Heavy gross contamination e.g. distal limb lacerations in hunting field
- Fractures or foreign bodies that need further treatment
24
Q
Outline the advantages of using arthroscopy for lavage for synovial sepsis in a horse
A
- Allows visualisation and surgical manipulation of regions e.g. heavily contaminated regions
- Removal of fractures/foreign bodies
- Debridement of osteomyelitis
- Resection of synovial proliferation in chronic cases
- Can facilitate further surgical intervention as required
25
In what cases is arthroscopic lavage for synovial sepsis in horses indicated?
- Infection is chronic or recurrent
- Heavy gross contamination
- Fractures or foreign bodies that need further treatment
- Wounds >24yrs old
26
In what cases is repeated open lavage for synovial sepsis in horses indicated?
Chronic, refractory or heavily contaminated cases, or to maintain arthrotomy wounds for continuous drainage
27
What are the disadvantages of repeated open lavage in the treatment of synovial sepsis in horses?
- Very expensive
- Time consuming
- Difficult to maintain sterility
- Chronic inflammation means poor prognosis for return to athletic function
28
Justify the use of systemic antibiotics in the treatment of synovial sepsis in horses
In most cases there is another source of sepsis, cutaneous wound, cellulitis or osteomyelitis which may not be affected by intra-articular antibiotics
29
Justify the use of intra-articular antibiotics in the treatment of synovial sepsis in horses
Reach 1000x the concentration of systemic antibiotics without systemic side effects
30
Identify the systemic antibiotics that are commonly used in the treatment of synovial sepsis
- Broad spec based on C+S
- Penicillin + aminoglycoside
- Or 3rd gen cephalosporins
- Enrofloxacin alternative option (not licensed, not for animals <3yo or lactating mares)
- Gentamicin most effective and least toxic given 6.6mg/kg IV SID
31
Identify the antibiotics that are used intra-articularly in the treatment of synovial sepsis in horses
- Gentamicin
- Amikacin
- Sodium penicillin
- Ceftiofur
32
Give alternative options to the typical antibiotics used in the treatment of synovial sepsis in horses
- Impregnated PMMA beads
- Bio-absorbable slow release drug
- Regional perfusion
33
Outline PMMA beads in the treatment of synovial sepsis in horses
- Best for low motion/chronically infected joints
- Slow release of anitbiotics over 2 weeks
- Only gentamicin available commercially, but can make own
- Mechanical effect can be consideration for long term issues in high motion joints
34
Outline bio-absorbable slow release antibiotics in the treatment of synovial sepsis in horses
- Commercially available only gentamicin impregnated collagen (high cost)
- Good for refractory cases
- Suitable in high motion joints, tendon sheaths
35
Outline regional perfusion of antibiotics in the treatment of synovial sepsis in horses
- Tourniquet and intravenous/intraosseus injection
- Most suitable for foals, or horses under GA
- Higher concentrations achieved with intra-articular administration
36
Describe the analgesia used in the treatment of synovial sepsis in horses
- Must use NSAIDs
| - DMSO
37
Explain why NSAIDs must be used in the treatment of synovial sepsis in horses
- Reduce joint pain
- Increase mobilisation
- Decrease joint stiffness
- Decrease Pg release
- reduce collagen joint destruction
- reduce risk of contralateral limb laminitis
38
Discuss the use of DMSO in the treatment of synovial sepsis in horses
- Administered into lavage solution
- Provides analgesia and anti-inflammatory effects
- Care with handling
39
Discuss bandaging in the management of synovial sepsis in a horse
- Essential, along with wound care
- Maintains sterility, provides comfort, optimal wound healing
- First layer should be sterile
- Bandage keep clean and dry to avoid reintroducing infection
40
Outline the post-operative care in a case of synovial sepsis in a horse
- Rest essential, but not complete box rest
- Once active inflammation resolved: passive flexion, gentle hand walking, in hand grazing
- Physiotherapy
- Gradually increase exercise
41
Explain the importance of passive flexion, hand walking etc. in the post-op care for synovial sepsis in horses
- Mobilise joint
- Improve drainage and lymphatic flow
- reduce oedema
- Promote lubrication
- Decrease capsulitis
42
What additional drugs can be used in the management of synovial sepsis in horses for long term treatment? How should these be used?
- Hyaluron, PsGAGs, low dose corticosteroids
- Best once infection resolved
- Any route other than intra-articular
43
Discuss the prognosis for synovial sepsis in adult horses
- Very good with appropriate treatment
- Prognosis for resolution of infection adn return to athletic function: >80%
- Prognosis for return to athletic function reduced in horses with pre-existing arthritis and articular damage
- Bony damage, osteomyelitis, severe contamination, wounds that cannot be closed, chronic wounds: worse prognosis
- Site of infection affects prognosis
44
Which sites are typically associated with a worse prognosis following synovial sepsis in mature horses?
- Distal tarsal joints
- Calcaneal bursal
- Navicular bursal infections
45
Outline the prognosis for synovial sepsis in foals and identify factors affecting the outcome
- 50% for resolution of infection, only 30% achieve racing performance
- Septicaemia, osteomyelitis and hypogammaglobulinaemia affect outcome
46
Where do tendon sheaths occur and what is their function?
- Points of friction, occur wherever tendons cross high motion joints e.g tarsal and carpal joins
- Surround and protect, enabling tendon to glide smoothly
47
Describe the tendon sheaths of the fetlock joint (name, location, structure)
- Common digital synovial sheath
- Reaches from distal cannon to middle phalanx
- Palmar aspect has 9 pouches
- Encloses superficial and deep flexor tendons
48
Describe the appearance of swelling of the fetlock tendon sheath
- Most easily visible proximal and palmar to fetlock joint
| - Also known as windgalls
49
What are tendon bursae?
- Fluid filled sacs that facilitate sliding at major pressure points e.g. between bones and muscles/tendons/ligaments or between skin and bones/muscles/tendons/ligaments
- Synovial structures with synovial membrane and synovial fluid
50
Explain the presence of synovial bursae
- Presence inconstant depending on mechanical challenges, age, body condition
- Trauma can lead to acquired bursae
51
Briefly outline the structure of tendons
- Collagen fibrils organised into fibres, then organised into parallel bundles
- Primary bundles (fibres) and secondary bundles (fascicles)
- Structure maintained by loose connective tissue - endo-, peri- and epitenon
52
Compare the roles of the endo-, peri- and epitenon
- Endo: holds fibres together to form fascicles
- Peri: holds fascicles together
- Epi: surrounds the whole tendon
53
Describe the structure of the point of insertion of tendons
transition from tendon to bone via fibrous cartilage which becomes progressively mineralised towards the bone
54
Explain the function of the patellar ligaments of the equine stifle
Locks stifle and maintains limb in a weight bearing position with minimal muscular effort
55
Explain the function of the cruciate ligaments of the stifle
Resist cranio-caudal movement of the stifle
56
Explain why ligaments have poor ability to heal
- Low metabolic funciton
- Poorly vascularised
- Poor innervation
57
Where does failure of tendons and ligaments commonly occur and why?
Mostly within the muscle or within the bone at the site of attachment - biomechanically very strong, attachments are weak points
58
Where do the flexor tendons of the equine distal limb originate?
Caudomedial humerus
59
Where does the suspensory ligament of the equine distal limb originate and insert?
- Origin: Palmar carpal ligament and metacarpal bone
| - Insertion: sesamoid bones (extensor branches)
60
Explain the value of ultrasonography of the equine distal limb?
- Structures involved can be identified
- Degree and extent of injury can be assessed
- Healing/response to treatment can be monitored
61
Describe the grading for changes in echogenicity in tendon injuries
- Type 1: slightly less echogenic than normal
- Type 2: half echogenic and half anechoic
- Type 3: mostly anechoic
- Type 4: completely anechoic
62
Describe the fibre pattern/alignment scoring using in ultrasonography for tendon injuries in horses
- 0: >75% fibres aligned parallel to target path
- 1: 50-75% of fibres aligned parallel to target path
- 2: 25-50% fibres aligned parallel to target path
- 3: <25% fibres aligned parallel to target path
63
Describe the normal ultrasonographic appearance of the SDFT
- Homogenic and echogenic
- Slightly less echogenic than DDFT
- NB training can cause 10% increase in CSA and mild decrease in echogenicity
64
Describe the normal ultrasonographic appearance of the DDFT
- Homogenic and echogenic
- Increased echogenicity compared with SDFt
- Hypoechoic region in hindlimb at insertion of ALDDFT
- Bilobed apperance in pastern
65
Describe the normal ultrasonographic appearance of the ALDDFT
Homogenous and echogenic
66
Describe the normal ultrasonographic appearance of the suspensory ligament
- Heterogenous: muscle, connective tissue, fat and ligament fibres
- Can contain hypoechoic areas (compare to contralateral limb)
- Branches are homogenous and echogenic
67
Compare the ultrasonographic appearance of a chronic healing tendon lesion vs. an acute lesion
Chronic healing lesions lack hypoechoic regions typically associated with acute lesions, but may remain grossly enlarged variable healing
68
Which transducer frequency should be use for ultrasonography of equine distal limb?
10MHz
69
What is the purpose of stand-off pads used in ultrasonography?
- Increase distance between transduce and superficial structures
- Adjust to uneven contours
70
When taking a history for lameness, what lameness specific questions should be considered?
- Prior lameness?
- Duration of lameness
- Onset and change in lameness
- Last shoeing
- Exacerbated by anything?
- Medications and response to treatment
- Any previous evaluations and if so, what was found?
71
In a lameness workup, what factors are of particular importance in the physical examination?
- Conformation
- Foot balance
- Distal limb conformation
- Comparative observation
- Posture (e.g. toe pointing?)
- palpation of hoof, FL, HL, soft tissues, synovial effusion, ROM
72
Briefly outline the palpation of soft tissues in the investigation of lameness
- Palpate flexed and extended
| - Looking for tendinitis and desmitis
73
Outline the assessment of ROM in a lameness examination (i.e the normal ROM for each joint in the limb of a horse)
- DIP cannot be assessed, PIP low motion joint cannot be assessed
- MCP joints: bulbs of heal touch ergot
- Carpus: high ROM, cannon can be brough almost parallel to radius
- Tarsus and stifle: flex together, cannon should come horizontal to ground
74
What would the ability to flex and extend the hock and stifle separately indicate in a horse?
- Are linked by peroneus tertius
- If ruptured, can flex hock and stifle separately
- Occurs secondary to hyperextension of hock
75
What signs of lameness should be looked out for in a dynamic lameness evaulation in the horse?
- Shortened strides/abnormal tracking
- Fetlock drop
- Arc of flight altered
- Abnormal landing of foot
- Head/pelvic movement (most reliable)
76
What would the following signs indicate in a horse at trot?
| Head nod when right FL placed
Lame on left fore
77
What would the following signs indicate in a horse at trot?
| Shortened strides on RH, hip rises higher on RHS
Right hind lameness
78
Identify the grade of lameness that fits with the following description:
mild, inconsistent lameness in straight line (subtle or inconsistent head nod or pelvic hike)
Grade 1
79
Identify the grade of lameness that fits with the following description: severe lameness; extreme head nod/pelvic hike; horse is lame in walk but can be trotted
Grade 4
80
Identify the grade of lameness that fits with the following description: moderate and consistent lameness (consistent head nod or pelvic hike, moving by several cm )
Grade 2
81
Identify the grade of lameness that fits with the following description: obvious, marked lameness (head and pelvis move by several cm) head and neck nod seen with HL lameness
Grade 3
82
Identify the grade of lameness that fits with the following description: severe, non-weight bearing lameness, horse cannot and should not be trotted
Grade 5
83
What may be seen when lunging a horse with a forelimb lameness?
- Exacerbation of weight bearing lameness on inside limb
- Exacerbation of swinging leg lameness of outside limb
- Distal injuries may be worse on hard, proximal injuries may be worse on soft
84
If a horse is investigated for lameness, and all other tests are negative but a flexion test is positive, how should this be interpreted?
Unlikely to be significant, if all else is negative
85
What are the options for diagnostic analgesia in the work up of lameness in horses?
- Perineural
- Intrasynovial
- Local infiltration
86
What conditions would contraindicate use of local analgesia in the investigation of equine lameness?
- Fracture
- Infection
- Temperament issues
87
What is required for intrasynovial anaesthesia for the investigation of lameness in a horse?
- 5 min sterile prep
- Sterile gloves
- Sterile technique
- Fresh bottle of anaesthetic
88
What is required in order for diagnostic analgesia to be a useful test?
Need consistent lameness
89
Describe the normal conformation of the equine forelimb when viewed from the front and from the side
- Front: limb biseced by vertical line from shoulder to ground
- Side: vertical intersects the elbow, carpal and metacarpophalangeal jionts
90
Describe the normal conformation of the equine hindlimb when viewed from the front and from the side
- Front: limb bisected by vertical line from the hip joint to the ground
- Side: vertical line from tuber ischium touches point of hock and entire plantar aspect of the metatarsus
91
What is the normal ground:dorsal hoof wall angle in the fore and hind limbs of a horse?
- Fore: 45-50˚
| - Hind: 50-55˚
92
Describe the normal mediolateral balance of a horses foot
Coronary band and weight bearing surface of the foot should be parallel to the ground and perpendicular to a vertical line that bisects the third metacarpal bone
93
What is a fluctuant swelling of the coronary band in the horse characteristic of?
Effusion of the distal interphalangeal joint
94
What is an obvious dip in the coronary band in the horse characteristic of?
Distal displacement of the distal phalanx
95
Compare the lameness on the lunge for a medial aspect of the foot vs other lesions
- Most lameness in the foot will be exacerbated when affect limb is on the inside of the circle
- If lesion is n medial aspect of foot, horse will likely be more lame when that limb is on the outside
96
Identify the flexion tests that are commonly carried out in the horse
- Distal forelimb (metacarpophalangeal joint and below)
- Proximal forelimb (carpus and above)
- Distal hindlimb (metatarsophalangeal joint and below)
- Proximal hindlimb (tarsus and above)
97
Outline the back examination in a horse
- Palpate specific muscles: stenomandibularis, brachiocephalicus - difficult, but can find and palpate fascial boundaries between 3 lanes (transversospinalis, longissimus, iliocostalis) in the Th-L region
- Palpate for pain, tension, spasm
- Flex spine - ventro, dorsi and lateroflexion, should have easy flexion over a few degrees
98
In horses, what may result from severe spasms of longissimus dorsi and other epaxial muscles on one side? How can this be identified?
- Functional scoliosis
| - Pressure over affected muscle is very painful
99
How is pain or instability of the pelvic girdle assessed in horses?
Push tuber coxae ventrally and medially using both hands
100
Discuss the use of radiography in the diagnosis of back pain in horses
- Thoracic: good, large lung fields, spinous processes and vertebral bodies easily identifiable
- Lumbar generally unrewarding
- Pelvic useful for fractures, arthritis
- Sacroiliac disease difficult to confirm radiographically
