Multiple limb lameness

Question 1

Types of multiple limb lameness (& their signalment, potential causes, etc)

Answer 1

• generalised osteoarthritis
• panosteitis
• septic arthritis
• Lyme dz (Borrelia burgdorferi)
• endocarditis and associated polyarthritis
• pulmonary osteopathy
• metaphyseal osteopathy
• rickets
• nutritional hyperparathyroidism
• osteogenesis imperfecta
• immune mediated arthritis

Question 2

What is the most common cause of multiple limb lameness?

Answer 2

• immune mediated arthritis

Question 3

Generalised OA - signalment, cause

Answer 3

• seen in the older dog
• little evidence of a genetically determined generalised OA
• hence this condition primarily arises in breeds which suffer from concurrent developmental dz such as elbow dysplasia, hip dysplasia or acquired dz such as cruciate rupture
  -> this is secondary OA

Question 4

Panosteitis - what is it? signalment

Answer 4

• inflammatory condition in multiple long bones
• most common in the young male (<2y) GSD

Question 5

Septic arthritis - how can it occur? presentation in young vs older animals

Answer 5

• in the younger animal it occurs in multiple joints
• in the older animal a single joint
• may occur following surgery or via haematogenous spread

Question 6

Pulmonary osteopathy - what is it? aetiology?

Answer 6

• a paraneoplastic syndrome with proliferative new bone on the limbs
• aetiology not clearly determined but may arise from vagal stimulation arising from arteriovenous shunting

Question 7

Metaphyseal osteopathy - what is it?

Answer 7

• inflammatory condition seen in young dogs
• characteristic radiographic changes
• prognosis is good to far

Question 8

Rickets - prevalence, what is it associated with?

Answer 8

• seen occasionally
• associated with poor diet as well as lack of sunlight

Question 9

Nutritional hyperparathyroidism - cause, what does it cause?

Answer 9

• all meat diet (high in phosphorus, low in calcium) in young animal
• poorly mineralised bones with multiple folding fractures and collapse of vertebrae

Question 10

Osteogenesis imperfecta - what is it?

Answer 10

• rare inherited dz which results in multiple fractures due to abnormal formation of bones

Question 11

Multiple limb lameness - signalment and hx clues

Answer 11

Age
- e.g. young dogs are more prone to vaccine associated polyarthritis, panosteitis and viral causes such as calicivirus infection in the cat

Breed predilections
- e.g. Sharpei fever
- sulphonamide induced polyarthritis in the Doberman (Dobermans shouldn’t have sulphonamides due to high prevalence of developing polyarthritis after administration)

Recent vaccination or drug administration
- e.g. potentiated sulphonamides

Recent tick exposure
- although Borrelia infection may not become apparent for 2-5months

Recently imported from abroad

Question 12

Clinical presentation

Answer 12

• generalised lameness in multiple joints sometimes with a shifting lameness
• may be worse in 1 limb but the animal should be seen to have poor movement generally with short stride lengths
• the joints may be visually or palpably swollen and painful on manipulation
• there may be accompanying muscle pain
• the animal may be systemically unwell with pyrexia
• there may be a hx of previous episodes
• other signs may accompany the lameness such as respiratory or GI signs

Question 13

Further investigations

Answer 13

• radiography
• arthrocentesis
• serology
• echocardiography & blood culture
• CSF tap
• liver/kidney/muscle/skin biopsies

Question 14

Radiography

Answer 14

• variable in its helpfulness e.g. rheumatoid arthritis will demonstrate a destructive pattern but systemic lupus erythematosus and idiopathic forms only soft tissue swellings
• radiograph other body systems such as lungs for pulmonary osteopathy and pulmonary adenocarcinoma in the cat
• radiograph all the joints showing CS and others
• radiographic and CS may not coincide in panosteitis

Question 15

Arthrocentesis

Answer 15

• generally performed on the more distal joints i.e. carpus, elbow, tarsus and stifle
• these are the more commonly affected joints
• laying the pt on 1 side and tapping all those on the non-dependent side is an easy way to proceed
• joint fluid may be watery, have a low viscosity and be obviously turbid
• normal gross appearance doesn’t rule out the condition
• cytology for immune mediated dz shows increased white cells, predominantly neutrophils as would a septic polyarthritis or vector borne dz such as Lyme dz
• collect for cytology, protein estimation and culture
• bacterial culture is best achieved by collecting into blood culture medium
• make smears of the joint taps, air dry and examine in house
• if there is evidence of a polyarthritis collect samples for serology or PCR for infectious conditions (e.g. Borrelia burgdorferi (Lyme dz), Brucella, Leishmania and Ehrlichia in the imported dog and serology for rheumatoid and anti-nuclear factor
• joint taps are obligatory for the investigation of the pyrexic animal even if the CS are not suggestive of polyarthritis

Question 16

Joint tap - how to

Answer 16

• aseptic skin preparation and technique
• collect into EDTA and plain tubes
• make smears and examine in house
• collect sample into blood culture media if suspect sepsis

Question 17

Appearance of synovial fluid

Answer 17

Examine gross appearance and volume
- colour and gross appearance
- viscosity-stringing?
- protein mucin clot time
- cell count
- cell morphology
— activity foamy macrophages - consistent with degenerative joint dz
— neutrophils - consistent with sepsis or if multiple joints a polyarthritis

Always interpret the synovial findings in the light of clinical signs

Question 18

Serology - use

Answer 18

RF, ANF, Borrelia, Brucella, Ehrlichia (RF and ANF are neither specific nor sensitive tests for rheumatoid arthritis or SLE)
Dx snap test can be used of the detection of Ehrlichia, Lyme, Dirofliaria and Anaplasma infections

Question 19

Echocardiography and blood culture - use

Answer 19

• if suspect a polyarthritis secondary to an endocarditis

Question 20

CSF tap - use

Answer 20

• if suspect concurrent immune mediated meningitis

Question 21

Liver/kidney/muscle/skin biopsies - use

Answer 21

• if suspect more widespread immune mediated dz

Question 22

Immune mediated polyarthritis - forms and their examples

Answer 22

Erosive forms
- rheumatoid arthritis
- Chronic feline erosive progressive polyarthritis
- more aggressive and serious form

Non-erosive forms
- immune-mediated polyarthritis (4 types)
- systemic lupus erythematosus
- feline non-erosive chronic progressive polyarthritis
- breed associated e.g. Sharpei fever and juvenile onset polyarthritis of Japanese akitas
- drug and vaccine associated polyarthritis’ e.g. sulphonamide and post-vaccinal
- polyarthritis/myositis and polyarthritis/meningitis syndromes

Question 23

Types of immune mediated non-erosive polyarthritis

Answer 23

Type I
- no underlying dz detected
- idiopathic
- most common form

Type II
- associated with infection elsewhere e.g. respiratory or urinary tract infection
- may spontaneously resolve with tx of the underlying condition or require immunosuppression

Type III
- associated with GI dz

Type IV
- associated with neoplasia e.g. myeloproliferative dz

Non-erosive chronic progressive polyarthritis in cats
- may be the same condition as the erosive form just a different manifestation of the same dz process

All present similarly clinically

Question 24

Types of non-erosive polyarthritis - vaccine reactions - what to do?

Answer 24

• may recur and benefits must be weight against potential risks when advising re subsequent vaccinations
• particularly after the calicivirus vaccine

Question 25

Types of non-erosive polyarthritis - systemic lupus erythematosus

Answer 25

- multi-system involvement with anaemia, leucopenia, thrombocytopenia, myositis, meningitis, glomerulonephritis - ANF positive and if 3 organ systems involved then a positive diagnosis - prognosis is poor

Question 26

Shar Pei fever - prevalence, onset, signs, tx

Answer 26

- common (as many as 1 in 4) and characteristic of the breed - juvenile onset - pyrexia - swollen hock joint although swelling is primarily periarticular - later development of renal amyloidosis and renal failure - tx symptomatically with pain relief, etc, potentially steroids to reduce inflammation

Question 27

Juvenile onset polyarthritis of Japanese Akitas - prevalence, signalment, prognosis

Answer 27

- less than 1y/o - poor prognosis - reasonably uncommon

Question 28

Rheumatoid arthritis - signs, diagnosis, prognosis

Answer 28

- sever and debilitating - destructive with radiographic lucencies - loss of articular surfaces and collapse of joint space and subluxation of the joints - RF (rheumatoid factor) positive but this can occur with other diseases - synovial biopsies show typical changes - several diagnostic criteria need to be satisfied to make this diagnosis - prognosis is poor and euthanasia is often required but is better in the cat

Question 29

Erosive forms of polyarthritis - signalment, signs, prognosis

Answer 29

- the erosive and non-erosive forms may be the same condition - a rare condition most common in the young male - a destructive polyarthritis - in both forms there is a marked proliferative reaction around the joints - joint subluxations can accompany the dz - an aggressive and debilitating condition - responds poorly to tx

Question 30

Polyarthritis and endocarditis - cause, signs, diagnosis, tx

Answer 30

- frequently sites as a cause of polyarthritis (septic and immune mediated) but uncommon or rarely diagnosed with a poor prognosis - intermittent pyrexia, lethargy and weight loss associated with several bacterial isolates - rapidly developing cardiac murmur often diastolic with aortic and mitral valves most commonly affected with an anaemia and leucocytosis - associated thromboembolism (both infected material and thrombi) which can result in renal failure - diagnosed by echocardiography and blood culture (at least 3 samples taken at periods of pyrexia - tx: long courses of antibiotics (based on culture) and anti-thrombotic

Question 31

Tx of joint associated limb lameness'

Answer 31

Non-immune mediated - if the underlying cause can be identified treat this e.g. antibiotics for septic arthritis and endocarditis Immune mediated - tx of the underlying cause in Types II, III & IV may result in the resolution of the signs but often immunosuppression is required - generally immunosuppression is required - management requires frequent monitoring particularly of liver enzymes and white cell and platelet levels - side effects of tx are common including myelosuppression and hepatopathies Analgesia Salvage procedures If medical management were to fail then surgical techniques can be employed including arthrodesis and joint replacements Arthrodesis and joint replacements have to be managed carefully as the underlying process will continue in other joints On occasions euthanasia will be the most appropriate option

Question 32

Immunosuppressive agents

Answer 32

Prednisolone - mainstay of tx - side effects common including PUPD, hepatopathies - start on 2-4mg/kg then reduce to minimum effective dose Azathioprine - used when preds are ineffective - not to be used in cats Chlorambucil - can cause myelosuppression Methotrexate - used with leflunomide in the tx of rheumatoid arthritis in cats Cyclosporin, cyclophosphamide, levamisole

Question 33

Analgesia for immune mediated joint dz

Answer 33

- NSAIDs to be avoided if using corticosteroids - paracetamol (in the dog) and opiates - bedinvetmab (Librela) and frunevetmab (Solensia) monoclonal antibody to nerve growth factor - weight reduction and hydrotherapy to maintain joint health

Question 34

Myopathies - categories

Answer 34

- inflammatory - non-inflammatory

Question 35

Myopathies - CS

Answer 35

In addition to the CS seen in polyarthritis there may be - muscle atrophy - reduced muscle tone and local reflexes - dysphonia, dysphagia and regurgitation - megaoesophagus - pyrexia in inflammatory myopathies - pain in the temporal muscles and a reluctance to open the mouth with a masticatory muscle myositis (eosinophilic temporal myositis) or, after a few weeks, marked muscle atrophy

Question 36

Inflammatory myopathies - examples

Answer 36

- masticatory muscle myositis (MMM) - immune mediated dz e.g. SLE or associated with polyarthritis - protozoal infections e.g. toxoplasma and neospora

Question 37

Non-inflammatory myopathies - examples

Answer 37

- genetic disorders e.g. Labrador myopathy (floppy Labrador) - corticosteroid induced (endogenous and exogenous) - endocrine associated e.g. Cushing's disease and hypothyroidism - metabolic abnormalities e.g. phosphofructokinase deficiency in the Springer spaniel

Question 38

Inflammatory and non-inflammatory myopathies - diagnosis

Answer 38

- CE - blood samples including CPK (creatinine phosphokinase), electrolytes, lactate and pyruvate - thyroxine for hypothyroidism or MMM antibodies if suspect masticatory myositis - acetylcholine receptor antibody serology for myasthenia gravis - toxoplasma and neospora serology - radiography for megaoesophagus - muscle biopsy (most important diagnostic step) to be send to Royal Dick School of Veterinary Studies, Easter Bush pathology - skin biopsy if associated skin lesions seen in dermatomyositis in the Shetland and Rough collie

Question 39

Muscle biopsy

Answer 39

- taken from the quadriceps, biceps femurs or triceps (0.5x0.5x1cm portions) - if suspect neuromuscular dz then cranial tibialis (on the lateral aspect of the proximal tibia) is a good muscle to biopsy - careful tissue handling is essential - samples are collected along the length of the fibres - they're placed in 10% formalin for H&E staining and also a fresh sample can be sent wrapped in moist gauze and cooled for freezing prior to electron microscopy

Question 40

Inflammatory myopathies - tx

Answer 40

- antibiotics for protozoal infections e.g. clindamycin - immunosuppressive doses of corticosteroids if autoimmune dz suspected

Question 41

Non-inflammatory myopathies - causes

Answer 41

Many different causes have been reported Breed associated - e.g. Labrador retriever (floppy Labrador) (centronuclear myopathy) - consider in any young animal (<6m) with generalised weakness or muscle atrophy/hypertrophy with accompanying dysphonia, dysphagia and megaoesophagus - a genetic test is available from Laboklin labs - diagnose with muscle biopsy - no tx Metabolic associated - e.g. phosphofructokinase deficiency in springer spaniels, pyruvate kinase deficiency in Basenjis, WHWT, Sussex and Clumber spaniels - anaemia with jaundice and bilirubinuria are more prominent signs - little evidence that dietary modifications help these conditions - avoid strenuous exercise and hyperthermia - a genetic test is also available at Laboklin Endocrine associated - e.g. hypothyroidism, Cushing's dz, hypoadrenocorticism, hyperthyroidism - treat the underlying condition Exogenous corticosteroid administration

Question 42

Myotonias - examples, signs, tx

Answer 42

- myotonia of chow chows - myotonia of miniature schnauzers - also reported in the cat - increased tone and poor relaxation after muscle stimulation - persistent dimpling after percussion with a hammer - walk a bit like a robot: take short, rigid strides - tx: procainamide mixelitine and phenytoin -- anti-dysrhythmic, allows relaxation of the muscles