Arthritides in domestic species Flashcards
What are arthritidies?
Conditions causing pain and dysfunction related to joints
What is arthritis?
What are 3 examples of included conditions?
Inflammation/degeneration of the joint
- Includes: osteoarthritis, immune-mediated arthritis, infective arthritis
What is a Diarthrodial joint
A specialised joint consisting of a synovial cavity allowing articulation between two or more bones
What are some examples of Diarthrodial joints?
- Ball and socket (e.g. coxofemoral)
- Hinge or ginglymus (e.g. elbow)
- Gliding (e.g. tarsometatarsal)
- Pivot (e.g. atlantooccipital)
Why are joint diseases important to animals and their owners?
- Cause of pain and suffering: welfare/duty of care
- Costs to client
- Loss of function/athletic use
What are the effects on clients when their pet has a joint disease?
- Animals living longer/emotional attachment
- Drug costs e.g. NSAID use
- Milk/productivity losses to farmer
What is the most common cause of euthanasia with horse insurance claims
Joint disease
What is the most common type of joint disease?
Degenerative joint disease
What type of motion is provided by diarthrodial joints?
Frictionless, pain-free motion
What are the overall components of a normal synovial joint
- Diarthrodial joints
- Hyaline cartilage covered bones
- Synovial fluid
- Fibrous joint capsule
Articular cartilage has a close relationship with … within the synovial joint
Subchondral bone
What is synovial fluid made of?
Ultrafiltrate of plasma plus protein (hyaluronic acid)
Describe the components of the fibrous joint capsule
- Synovial membrane
- Nerves and blood vessels
- Supportive ligaments/tendons e.g. collateral, muscular
What is osteoarthritis?
Degenerative condition ultimately leading to cartilage breakdown and loss of function (end-stage)
Describe the structure of articular cartilage
Highly specialised tissue: predominately extracellular matrix with a low density of articular chondrocytes
What is the function of chondrocytes?
Maintenance of the matrix
What are the components of the matrix?
Collagens (80-90% type II), proteoglycans and water
What are the functions of collagens and proteoglycans within the matrix?
- Collagens confer shear resistance
- Hydrated proteoglycans provide compression
Osteoarthritis is thought of as a disease of which part of the synovial joint?
Articular cartilage
Which tissues contribute to the disease progression/clinical signs of osteoarthritis?
- Articular cartilage
- Subchondral bone
- Synovial membrane
- Joint capsule
- Ligaments
- Fat pad
What are some possible predisposing factors for osteoarthritis?
- Exercise/ trauma/ biomechanics
- Developmental orthopaedic disease
- Obesity
- Genetics
- Sepsis
- Repeat medications
- Ageing
What processes occur within a joint with osteoarthritis?
- Neoangiogenesis
- Neurogenesis
- Synovial fibrosis and inflammation
- Osteophyte formation
- Subchondral bone remodelling
What questions should be asked when obtaining the history of a patient with osteoarthritis?
- Age, signalment, use, breeding
- Level of exercise
- Determine onset and progression of disease
- Response to medication
- Other medical issues (e.g. immune mediated)
Describe the clinical exam of a patient with osteoarthritis?
General physical examination:
• TPR, thoracic auscultation etc
• Assessment of body condition, conformation, muscling
Lameness examination:
• Observation, palpation, manipulation and movement
• Pain, thickening, effusion, range of motion
Name some radiographic signs of osteoarthritis
- Soft tissue swelling
- Osteophytosis
- Enthesiophytosis
- Subchondral bone sclerosis
- Intra-articular mineralisation (e.g. meniscus)
- Fragmentation/joint mice
- Collapsed joint space
- Subchondral bone cysts
What are the 4 aims of osteoarthritis therapy?
- Provide analgesia
- Control articular inflammation
- Limit damage to articular tissues
- Promote healing of damaged cartilage – the Holy Grail!
What are some considerations/factors for the efficacy of treatments for osteoarthritis
- Heterogeneity of the disease
- Poor correlation between imaging and disease process
- Lack of reliable indicators of disease process
- Inter-animal variation
- High expectations/demands of owners
What are the conservative methods for managing a patient with osteoarthritis?
- Rest/restricted activity
- Weight loss
- Exercise
Which drugs can be used to medically manage osteoarthritis?
- NSAIDs
- Corticosteroids
- Hyaluronic acid
- Pentosan polysulphate
- Bisphosphonates
- Nutraceuticals
What are the main benefits of NSAIDs?
Anti-inflammatory, anti-pyretic, analgesic
Anti-inflammatory and analgesic effects of NSAIDs is via ?
Cycloxygenase (COX) inhibition
Name some NSAIDs used in SA practice
- Carprofen (Rimadyl)
- Meloxicam (Metacam)
- Phenylbutazone
- Paracetomol/codeine (Pardale V)
- Firocoxib (Previcox)
Name some NSAIDs used in equine practice
- Phenylbutazone (Equipalazone)
- Flunixin (Finadyne)
- Firocoxib (Equiox)
- Carprofen (Rimadyl)
- Ketoprofen (Ketofen)
How do corticosteroids work in the body?
- Bind to cytoplasmic and nuclear receptors
- Inhibit cytokines (eg. IL-1)
- Altered signalling pathways and gene expression
What are the pros/cons of corticosteroid use?
- Variability in efficacy and duration of action
- Cheap and effective
- Potential steroid-induced arthropathy reported (repeat usage)
Hyaluronic acid is a normal component of?
Synovial fluid and articular cartilage
What are the actions of hyaluronic acid?
- Chondroprotection (reduces chondrocyte apoptosis)
- Anti-inflammatory
- Stimulate proteoglycan synthesis
- Mechanical effect (improves viscosity)
- Limits subchondral bone changes
- Analgesia (bind to stretch receptors)
Pentosan polysulphate is marked as a DMOAD, what does that stand for?
Disease modifying osteoarthritis drug
What are the actions of Pentosan polysulphate?
- Enhances proteoglycan synthesis
- Reduction in articular cartilage fibrillation
- Fibrinolytic: improves joint perfusion
- Improves synovial fluid viscosity
- Increases release of free radical scavengers
Describe the actions of bisphosphonates
Bisphosphonates are potent inhibitors of bone resorption:
- Inhibition of osteoclasts
- May also inhibit collagenase release in chondrocytes/ synovial cells
What are neutraceuticals?
Dietary products which provides medical or health benefits, including the prevention and treatment of disease
How can osteoarthritis be surgically treated?
- Arthroscopy
- Joint replacement: hip/elbow
- Arthrodesis
What is arthroscopy?
- Assess damage
- Debride cartilage defects
- Flushing inflammatory mediators
What is arthrodesis?
- Destruction of cartilage
- Bone-bone primary healing
What are the main features of immune mediated joint disease?
- Usually present as polyarthritis and can be erosive or non-erosive (erosive = poor prognosis)
- Predominately idiopathic
- Most relate to abnormal activity of immune cells and antigen-presentation
Describe the pathophysiological events involved in immune mediated joint disease
- Early changes occur in synovium
- > Chronic antigenic stimulation
- > Antibodies to infective agents or macromolecule modification leading to inappropriate immune response
- Development of immune-complexes that get deposited or expressed within the joint creating a strong and prolonged inflammatory reaction
How is immune mediated polyarthritis diagnosed?
- Multiple limb joint pain/swelling, generalised stiffness, shifting lameness, neck pain, lethargy, PUO
- Variable and intermittent in character
- Secondary OA and fibrosis/joint deformities with chronic cases
Which test is used to manage immune mediated polyarthritis?
Synoviocentesis
During the clinical exam/diagnostics, what characteristic involvements of other systems is seen with immune mediated polyarthritis?
- Haematology/ biochemistry, thoracic/ abdominal x-ray
- Anaemia, leucopenia, thrombocytopenia, raised globulins, low albumin
- Urinalysis: proteinuria
What can be seen with diagnostic imaging in immune mediated polyarthritis?
- Early: non-specific joint effusion
- Late: erosive versus non-erosive; OA
What is the treatment of choice for immune mediated polyarthritis?
Corticosteroids
Infective arthritis is also known as?
Synovial sepsis
What is the causative agent of synovial sepsis?
Inflammatory arthropathy due to an infective organism
- Usually bacteria but occasionally fungi, mycoplasma, rickettsia, protozoa and viruses
What are the causes of infective arthritis/synovial sepsis?
- Haematogenous
- Trauma/wound
- Iatrogenic
Describe Haematogenous infective arthritis
- Often separate focus of infection identified e.g. umbilicus, pneumonia, diarrhoea, septicaemia
- More common (but not exclusively) in neonates (due to failure of passive transfer)
How can trauma/wounds be the cause of infective arthritis?
- Often seen in horses (esp. distal limb wounds due to sparse soft tissue coverage)
- Cat bites e.g. Pasteurella multocida
- Adjacent infection (e.g. complicated sole ulcer leading to septic arthritis of DIPJ in cattle)
What are iatrogenic causes of infective arthritis?
e.g. post-joint/fracture surgery or following intra-articular injection (often Staphlococcus spp.); more common in small animal surgery
Describe the pathophysiology of infective arthritis/synovial sepsis
Marked inflammatory response:
- Vasodilation and influx of neutrophils
- Release of inflammatory cytokines/enzymes
- Fibrin clots trap bacteria
- Cartilage destruction and extension to subchondral bone -> osteomyelitis
Why does the formation of fibrin clots in the pathophysiology of infective arthritis/synovial sepsis have a negative effect?
- Protects bacteria – prolonging the problem
* Reduces synovial nutrient exchange which has a negative effect on synovial function
What are the clinical signs of infective arthritis/synovial sepsis
- Acute onset, severe lameness
- Stiffness/lying down/pyrexia
- Wound near/over joint
- Pain on palpation/ articular swelling
What are 3 differential dignoses for infective arthritis/synovial sepsis ?
- Traumatic joint injury (ligament/fracture)
- Osteochondrosis
- Bursitis/hygroma/cellulitis
Which technique is used to truly diagnose infective arthritis/synovial sepsis ?
Synoviocentesis
Describe the features of normal synovial fluid
- Pale yellow, high viscosity
- w.b.c <1x109/l and total protein <20g/l
- <10% neutrophils
Describe the features of septic synovial fluid
- Serosanguinous/ turbid/ reduced viscosity
- w.b.c.>10-20x109/l and total protein >30-40g/l - Significant increase in WBC and protein
- > 90% neutrophils
What are the 3 principles of treatment for infective arthritis/synovial sepsis?
- Treat underlying cause/infective agent (don’t always know the agent though)
- Systemic and local antimicrobials
- Remove inflammatory mediators (joint lavage)
What is the cause of Lyme disease?
Tick-borne spirochaete Borrelia burgdorferi
What are the features of Lyme disease?
• Multisystemic, inflammatory disorder
- Dogs present with inflammatory, non-erosive arthropathy with shifting lameness and swollen joints
- Also reported in horses (low grade pyrexia, stiffness, joint swelling, lethargy, skin lesions)
Describe what would be seen on Synoviocentesis for a case of Lyme disease?
- Increased cell count with 80-90% PMNs
- Rare to culture B.burgdorferi (PCR or serology)
How is Lyme disease treated?
doxycycline (30 days+)
