Lecture 29 4/8/25 Flashcards
Which sedative medications can be used to safely restrain an equine patient and limit secondary trauma?
-xylazine
-detomidine
-acepromazine
-butorphanol
What are potential systemic problems that can occur in patients with musculoskeletal issues?
-hypovolemic shock due to hemorrhage
-fluid and electrolyte losses with sweat
-resp. compromise with head, neck, and thoracic injuries
-systemic infection and/or endotoxemia with severe and/or chronic infections
What is most important regarding the musculoskeletal exam?
-localizing the injury and identifying affected anatomy
-determine the level of weight bearing
Which diagnostics are primarily used for musculoskeletal problems in equine?
-radiographs
-ultrasound
-advanced imaging
What are the causes of non-weight bearing lameness in horses?
-foot abscess* (most common)
-fracture*
-septic synovial structure*
-luxation
-lacerations of support structures
-lacerations/punctures of hoof
-laminitis
What are the characteristics of fractures in equine patients?
-present with acute, severe, non-weight bearing lameness
-diagnosed with rads
-most require referral
-prognosis varies with location, open vs closed, and athletic ability/expectations
-must be stabilized prior to transport
What are the characteristics of synovial sepsis?
-common emergency
-causes significant inflammation
-osteoarthritis and cartilage damage are common outcomes
-potential for loss of function or life
-commonly caused hematogenously in foals and via penetrating wounds in adults
What are the types of septic arthritis based on structure involved?
-synovitis: joints
-tenosynovitis: tendon sheaths
-bursitis: bursas
Why are the distal limbs prone to synovial infections?
combination of many synovial structures and poor soft tissue coverage; even small wounds can lead to infection
How can iatrogenic septic arthritis best be prevented?
adequate disinfection, aseptic technique, and client communication with every joint surgery or injection
What is the pathogenesis of septic arthritis?
-direct introduction of bacteria
-low fluid shear
-bacteria adhere, reproduce, and cause infection
What are the potentiating factors for septic arthritis?
-foreign material
-devitalized tissue
-number and nature of organism
-immune response
What is the pathophysiology of septic arthritis?
-colonization incites inflammation
-degradation of hyaluronan, collagen, and proteoglycan
-synoviocytes and chondrocytes are activated
-effusion forms
-fibrin formation
-pannus tissue formation
-cartilage matrix breakdown
-chondrocyte death
-persistent osteoarthritis
What are the clinical signs of septic arthitis?
-acute, severe, non-weight bearing lameness
-joint effusion
-possibly elevated digital pulses
-elevated acute phase proteins (fibrinogen, SAA)
Why is synoviocentesis done in joints with suspected septic arthritis?
-evaluation of wound communication
-fluid collection and analysis for cytology
-sample collection for culture (gold standard)
What is assessed on synovial fluid analysis?
-color and quality
-nucleated cell count and cytology
-total protein
-SAA
-culture and sensitivity
What is normal vs abnormal for synovial fluid color and quality?
*normal:
-yellow
-clear
-viscous
*abnormal:
-red, orange, or bright yellow
-opaque
-fibrinous
-non-viscous
What is normal vs abnormal for synovial fluid nucleated cell count and cytology?
*normal:
-</= 3,500 cells/uL
-primarily mononuclear cells on cytology
*abnormal:
-5,000 to 30,000+ cells/uL
*definitive for sepsis:
-> 90% neutrophils
-bacteria present
What are the characteristics of total protein in synovial fluid?
-normal is less than 2 g/dL
-animals are more likely to survive if TP is less than 6 g/dL
When should infection be suspected based off cell count and total protein results?
total nucleated cell count of 20,000 cells/uL or more combined with a TP greater than 3.5 g/dL
What are the characteristics of SAA?
-increases with both non-infectious and septic arthritis
-not affected by repeat centesis
-peripheral SAA typically used to evaluate clinical course rather than diagnose
What are the characteristics of culture and sensitivity of synovial fluid?
-gold standard for diagnosis
-poor sensitivity
-also possible to do PCR
-Staph. aureus and mixed infections are most common
What is evaluated on rads when concerned about septic arthritis?
-look for fractures and osteomyelitis
-gas indicates communication
-can use contrast for better results
What is evaluated on ultrasound when concerned about septic arthritis?
-soft tissue injury
-joint capsule thickening
-synovial effusion
-fibrin accumulation in fluid
What are the treatment steps for septic arthritis?
-broad spectrum antimicrobials
-anti-inflammatories
-wound care
-synovial lavage via needle lavage or arthroscopy/tenoscopy/bursoscopy
What are the characteristics of endoscopic treatment for septic arthritis via arthroscopy/tenoscopy/bursoscopy?
-allows for high volume fluid lavage
-can physically remove debris, fibrin, and necrotic tissue
-allows for thorough evaluation of joint
-requires GA
-expensive
What are the characteristics of needle lavage as treatment for septic arthritis?
-allows for high volume fluid lavage via “through and through” technique
-preferably performed under GA but can use regional analgesia
-may provide similar outcomes to arthroscopy
-needles are too small to remove fibrin clots
-cannot fully evaluate joint
What is the prognosis for septic arthritis?
-85 to 93% will survive to discharge
-56 to 81% will return to previous level of function
What are negative prognostic indicators in septic arthritis?
-delayed treatment
-elevated synovial total protein
-more than 1 endoscopic procedure
-presence of osteomyelitis
-owners unrealistic regarding cost and return to function
What are the characteristics of foot abscesses?
-acute, non-weight bearing lameness
-bacterial penetration leads to infection in region of sensitive laminae
-pressure build up causes severe pain
-will be hoof tester positive
-can do rads
What are the steps to treatment for foot abscesses?
-establish ventral drainage
-remove necrotic tissue
-daily flush/soak with disinfectant
-bandage foot
-systemic antibiotics NOT necessary
What are the characteristics of hoof puncture wounds?
-risk injury and contamination of deep structures
-can impact P3, DIP joint, DDFT, tendon sheaths, navicular bone, and navicular bursa
-emergency!
-penetrating objects are contaminated and wound seals quickly
-referral often required
Why should puncture wounds be radiographed before removing the penetrating object?
the penetrating object will show exactly which structures have been impacted
What are the steps of a street nail procedure for treating hoof punctures?
-regional block
-remove horn
-resect DDFT
-curette bone
How are the synovial structures impacted by puncture wounds treated?
-joint/synovial lavage
-endoscopic treatment
What is the aftercare for hoof punctures?
-multiple lavages may be needed
-bandage changes
-regional limb perfusions
-systemic antibiotics
-anti-inflammatories
What is the prognosis for hoof punctures?
-guarded
-improved outcome with surgical management
What are the characteristics of lacerations/degloving injuries?
-extensive avulsion injuries that expose bone and damage blood supply
-damage to periosteum occurs; interferes with granulation tissue formation and bone proliferation; leads to sequestrum
-wounds expand for 11 to 21 days before granulation tissue and myofibroblasts counteract expansion
-heal more slowly than wounds on trunk
-heal faster in ponies
What is the standard treatment for lacerations/degloving injuries?
-thorough exam of patient
-analgesia
-clean
-explore
-debride
-close +/- drain
-prepare owners; closure will dehisce
What are the characteristics of bone sequestrums?
-periosteal trauma leads to ischemia and necrosis
-avascular bone becomes sequestered by granulation tissue from viable bone
-bacterial colonization occurs
-body attempts to get rid of avascular/infected bone; leads to persistent exudate
What are the characteristics of rads as a diagnostic for bone sequestrum?
-will see sclerotic segment of bone surrounded by radiolucent osteolysis
-should radiograph wounds with exposed bone 10 to 14 days after injury to check for sequestrum
What is the treatment for bone sequestrum?
removal after formation of involucrum
What are the characteristics of cellulitis?
-disseminated infection under skin
-clinical signs include severe swelling/stovepipe limb, lameness, and possible fever
-diagnosed via rads, ultrasound, and culture
-do NOT perform synoviocentesis; will introduce infection
What is the treatment for cellulitis?
-systemic antibiotics
-NSAIDs
-sweat bandages
-identify, lance, and lavage abscess pockets
What are potential complications of cellulitis?
-contralateral limb laminitis (overuse)
-skin necrosis
-septic synovial structures
-hoof capsule evulsion
What are the layers of a bandage?
-primary layer consisting of dressing that is secured to wound with gauze
-secondary layer that pads the wound
-tertiary layer that is porous to air and waterproof; applied distal to proximal
What are the characteristics of tetanus?
-caused by Clostridium tetani
-anaerobic and spore-forming
-abundant in soil
-produces neurotoxin
-superficial wounds can result in clinical tetanus
What are the AAEP guidelines for tetanus vx in adults presenting with wounds?
-no need for vx. if vaccinated within last 6 months
-revaccination needed if vaccinated over 6 months ago
-tetanus antitoxin and full vaccination needed if unvaccinated or vaccine history unknown
