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Flashcards in Equine MSK diseases Deck (100)
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List the causes of equine synovial sepsis in adults

- Trauma
- Post injection
- Post-surgery
- Idiopathic


What is the most common cause of synovial sepsis in foals?

- Haematogenous spread of infection
- Septicaemia next most common cause


What are the most common pathogens identified in equine synovial sepsis?

- Aerobic or facultative anaerobes
- E. coli, Streps, Staphs
- If traumatic, often mixed infection including Clostridia


How may trauma lead to synovial sepsis in the horse?

- Direct inoculation of the joint
- Abscess erosion into joint after initial injury
- Osteomyelitis


What condition would the following findings be indicative of in a horse?

- Warm joint
- Joint effusion
- Localised oedema/cellulitis
- Pain on palpation and flexion
- Marked lameness


Describe the appearance of an open joint with synovial sepsis in horses

- Active discharge of synovial fluid from wound
- Viscous synovial fluid initially, the becomes more watery
- Lameness less severe vs. closed


Describe the appearance of a closed joint with synovial sepsis in horses

- 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


Outline the method for synoviocentesis in horses

- 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


What is a potential complication for synoviocentesis in chronic wounds in horses?

Cellulitis may be extensive, preventing access to joint


In which cases is synovial proliferation most likely to occur in horses?

- Fetlock proximal pouches, tarsocrural joints
- Chronic synovitis
- Chronic infection
- Open joints where most of fluid has drained


What should be used to collect the synovial fluid from synoviocentesis in a horse?

EDTA, +/- culture bottle


Outline how synovial proliferation can be overcome in order to obtain a sample from synoviocentesis in a horse

- 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)


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

- 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


How can it be determined whether or not a wound is communicating with the joint space in horses?

- 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


What should be done prior to removing a needle following synoviocentesis in horses?

- 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


When is radiogrpahy indicated in the investigation of synovial sepsis in horses?

- Where there is a chance of osteomyelitis
(all foals)
- Any causes of blunt trauma
- Possibility of fracture
- Foreign body


If radiography is performed prior to synoviocentesis, what does gas in the joint capsule indicate in horses?

Open joint


Outline the role of ultrasonography in the investigation of synovial sepsis in horses

- Identify radiolucent foreign bodies
- Soft tissue damage e.g. SDFT in plantar calcaneal injuries, DDFT in medial hock and tarsal sheath injuries


What are the principles of synovial sepsis treatment in horses?

- Must be ASAP and aggressive
- Systemic and intra-articular antibiotics
- Joint lavage and drainage


What are the options for lavage in a case f synovial sepsis of a horse?

- Through and through lavage
- Arthroscopic lavage
- Repeated open lavage and drainage


Outline the aspects that must be ensured when performing through and through lavage for a case of synovial sepsis in a horse

- 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


What portals should be used for through and through lavage of a tarsocrural joint in synovial sepsis in a horse?

- Dorsomedial
- Dorsolateral
- Plantaromedial
- Plantarolateral
- Move ingress through all of these


When if through and through lavage for synovial sepsis not a good option?

- Chronic or concurrent infection
- Heavy gross contamination e.g. distal limb lacerations in hunting field
- Fractures or foreign bodies that need further treatment


Outline the advantages of using arthroscopy for lavage for synovial sepsis in a horse

- 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


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


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


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


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


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


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