Page 1598 - Cote clinical veterinary advisor dogs and cats 4th

804 Polyarthritis

distal) should arouse suspicion. Confirmation from nonseptic arthritis (only occasionally with NSAIDs (e.g., meloxicam 0.1 mg/kg
rests on arthrocentesis with fluid analysis of mul- are organisms seen), although the presence PO q 24h).
VetBooks.ir changes. Further testing (tick titers, cultures, ○ Culture: synovial fluid cultures are often Chronic Treatment 2
of degenerate or toxic neutrophils suggests
tiple joints and radiography to evaluate erosive
septic arthritis.
• IMPA: prednisone/prednisolone 1.1 mg/kg
screening for cancer) is required to identify an
underlying cause and guide management. Suc-
> 25 kg; [p. 609] for body surface area
70%). When septic arthritis is suspected,
cessful management requires that any underlying negative (false-negative rates of 20%- PO q 12h (20 mg/m PO q 12h for dogs
cause be identified and treated. A diagnostic and consider additional cultures of synovial conversion) until resolution of signs (usually
treatment approach is presented on p. 1441. membrane, blood, and/or urine. Special 2-4 weeks), then slowly reduce the dose and
media may be required to culture L-form administer q 48h. Average of 3-6 months
Differential Diagnosis bacteria and Mycoplasma. but rarely lifelong treatment is required.
• Neurologic disease (e.g., spinal cord or brain • Titers and/or polymerase chain reaction • If glucocorticoid’s adverse effects are marked
disorders, neuromuscular diseases) (PCR): B. burgdorferi, E. ewingii, A. or high doses are necessary to suppress
• Muscular disease (e.g., polymyositis) phagocytophilum, Bartonella spp, Leishmania signs, consider other immunosuppressive
• Orthopedic disease (e.g., bilateral cranial • Echocardiogram: suspected bacterial endocar- drugs such as azathioprine, leflunomide,
cruciate ligament rupture, degenerative joint ditis (e.g., heart murmur, especially if recent cyclosporine, cyclophosphamide, with lower
disease) onset and/or diastolic [p. 294]) dosages of glucocorticoids.
• Cardiac disease (e.g., pericardial effusion) • Serum antinuclear antibody and rheumatoid • Shar-pei fever requires intermittent long-term
• Metabolic disease (e.g., hypoglycemia, factor: suspected SLE or rheumatoid arthritis, treatment.
hypocalcemia) respectively; the tests have limited accuracy. • Septic arthritis: antibiotics required until 2
• Hematologic disease (e.g., acute blood loss) • Cerebrospinal fluid tap (pp. 1080 and 1323) weeks after infection has resolved; often a
if meningitis is suspected minimum of 6 weeks.
Initial Database • Thoracic radiographs and abdominal ultra-
• Orthopedic (p. 1143) and neurologic (p. sound exam to evaluate remote infection, Nutrition/Diet
1136) exams to rule out other disorders GI disease, or neoplasia Caloric control is necessary to avoid weight gain
• CBC, serum biochemistry profile, urinalysis by patients receiving glucocorticoids.
○ Anemia and leukocytosis are common in TREATMENT
idiopathic polyarthritis but are nonspecific. Drug Interactions
Thrombocytopenia may suggest vector- Treatment Overview Consult a formulary for possible interactions.
borne infection. Treatment depends on cause. Sometimes, despite
○ Serum chemistry profile to assess organ treating the underlying cause, a course of pred- Possible Complications
function nisone is required to resolve the polyarthritis. • Secondary infections from immunosuppres-
○ Proteinuria may be indicative of GN For cases of IMPA, immunosuppressive doses sive drugs
(immune mediated) or amyloidosis of predniso(lo)ne are the treatment of choice, • Prednisone has many potential adverse effects.
• Radiographs to distinguish erosive from and after resolution of clinical signs, usually • Azathioprine: myelosuppression, hepatotoxic-
nonerosive polyarthritis within 2 weeks, glucocorticoids should be slowly ity, acute pancreatitis; avoid in cats
○ Erosive polyarthritis is characterized by tapered over 4-6 months. Insufficient dosages • Leflunomide: hepatotoxicity, gastrointestinal
subchondral bone destruction, seen as and/or administration for insufficient periods upset, cytopenias
an irregular joint surface or punched-out are important causes of treatment failure.
erosion of bone at the joint space (p. 888). Recommended Monitoring
In advanced cases of joint deformity, loss of Acute General Treatment • Primarily resolution of clinical signs; ideally,
mineralization of the epiphysis and calcifica- • Doxycycline 10 mg/kg PO q 24h for 28 repeat arthrocentesis to see if cell counts have
tion of soft tissues of the joint may be seen. days for tick-borne infections, Mycoplasma, returned to normal.
Often affects distal joints most severely. and L-form bacteria • Monthly CBC, liver enzymes for animals
○ Nonerosive polyarthritis has no bony ○ Instruct clients to administer a bolus of receiving immunosuppressive drugs.
abnormalities; signs of joint effusion and water or morsel of food after each dose
soft-tissue swelling may be apparent. to enhance esophageal transit. PROGNOSIS & OUTCOME
• Prednisone/prednisolone 1.1 mg/kg PO
Advanced or Confirmatory Testing q 12h initially for nonerosive and erosive • Nonerosive IMPA: good to guarded, ≈30%
• Arthrocentesis (p. 1059); two or more joints noninfectious IMPA of cases relapse and may be difficult to
should be sampled. • Cyclosporine or leflunomide are effective control or may require lifelong treatment
○ The tarsi and carpi are especially useful alternative treatments for IMPA. • Juvenile hereditary arthritis of Akitas: very
because of frequency of involvement and • Broad-spectrum antibiotics (e.g., amoxicillin- poor; does not respond to immunosuppres-
ease of access. clavulanate 22 mg/kg PO q 12h) or sive therapy
○ Gross appearance: normal synovial fluid is cephalosporins (e.g., cephalexin 22 mg/kg • Calicivirus infection of cats: excellent; gener-
viscous (tenacious), scant in volume, and PO q 8h [dogs], 20 mg/kg PO q 12h [cats] ally resolves in 3 days with supportive care
clear, whereas synovial fluid of animals or cefadroxil 22 mg/kg PO q 12-24h [dogs • Noninfectious erosive arthritis: guarded;
with polyarthritis is generally thin/watery and cats]) pending cultures in suspected or arthrodesis or splints may improve quality
and may be copious (several milliliters) confirmed cases of septic arthritis of life
and potentially turbid (more so with • Surgical joint lavage and drainage sometimes • Infectious arthritis: provided the arthritis is
infectious/septic polyarthritis). are required for septic arthritis. nonerosive and the infection can be treated,
○ Synovial fluid analysis: neutrophils pre- • Analgesia may be required, but avoid com- the prognosis is good.
dominate in inflammatory polyarthritis bination of nonsteroidal antiinflammatory
(distinguishing them from the more drugs (NSAIDs) and glucocorticoids. Pain PEARLS & CONSIDERATIONS
common degenerative arthropathies), and often resolves quickly with appropriate treat-
total cell counts are always > 3000/mcL, ment of IMPA or vector-transmitted disease. Comments
often ≥ 40,000/mcL. Cytologic exam is Shar-pei fever or other arthropathies not • Polyarthritis should be suspected in any
seldom helpful in distinguishing septic treated with glucocorticoids may be treated animal that is reluctant to walk or in any

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