Page 1230 - Small Animal Internal Medicine, 6th Edition

1202 PART X Joint Disorders

BOX 69.1
VetBooks.ir Classification of Polyarthritis in Dogs

Infectious
Bacterial
Mycoplasma
Rickettsial
Lyme borreliosis
Leishmaniasis
Fungal
Viral

A Noninfectious, Nonerosive
Idiopathic immune-mediated polyarthritis (IMPA)
Systemic lupus erythematosus (SLE)
Reactive polyarthritis (bacterial, fungal, parasitic,
neoplastic, enterohepatic, drug reaction, vaccine
induced)
Breed-associated syndromes
Polyarthritis (Akita, Newfoundland, Weimaraner)
Polyarthritis/meningitis (Akita, Beagle, Bernese
Mountain dog, Boxer, German Shorthaired Pointer)
Polyarthritis/polymyositis (Spaniels)
Familial Shar-Pei fever
Lymphoplasmacytic synovitis

Noninfectious, Erosive
B
Rheumatoid-like arthritis
Erosive polyarthritis of Greyhounds
FIG 69.5
(A) Two-year-old German Shepherd dog/Labrador Retriever
cross with reactive polyarthritis. The dog was seen because
of a 3-month history of shifting leg lameness and weight idiopathic immune-mediated polyarthritis. This disorder can
loss. There was joint swelling and pain and a grade IV/VI be diagnosed only by ruling out the other causes of polyar-
diastolic cardiac murmur. Synovial fluid was inflamed but thritis, but it is the most common form of polyarthritis diag-
sterile. (B) A cardiac ultrasound study suggested infective nosed in dogs (Box 69.1). It is especially common in sporting
endocarditis of the aortic valve, which was confirmed by and large breeds. Dogs of any age can be affected, but the
postmortem evaluation. incidence peaks at 2.5 to 4.5 years. Idiopathic immune-
mediated nonerosive polyarthritis is uncommon in cats.
Serology or PCR testing may be necessary to evaluate for
systemic infections known to cause reactive polyarthritis Clinical Features
(Bartonella, Anaplasma and Ehrlichia spp). The most common manifestations of idiopathic IMPA are
Clinical signs in dogs with reactive polyarthritis typically cyclic fever, stiffness, and lameness. Multiple joints are
include cyclic fevers, stiffness, and lameness. Synovial fluid usually involved, with the small distal joints (i.e., carpus,
analysis reveals an increase in both white blood cell (WBC) hock) affected most frequently. Approximately 20% to 50%
count and the percentage of neutrophils in affected joints, of affected dogs lack palpable joint effusion or joint pain.
but synovial fluid culture is negative. Radiographically, the Cervical pain and vertebral hypersensitivity are sometimes
only finding is joint swelling. present, reflecting either intervertebral facetal joint involve-
Treatment must be directed at eliminating the underlying ment or the presence of concurrent steroid-responsive
disease or antigenic stimulus whenever possible. If this can meningitis-arteritis (see Chapter 64). Some affected dogs are
be achieved, polyarthritis usually resolves without additional not obviously lame but are evaluated because of a vague
therapy. Short-term low-dose glucocorticoid therapy (pred- history of decreased appetite or fever of unknown origin.
nisone, 0.25-1 mg/kg PO q24h) or NSAID therapy may be
warranted to control synovitis in severe cases. Diagnosis
Idiopathic IMPA is diagnosed on the basis of the results of
IDIOPATHIC IMMUNE-MEDIATED synovial fluid analysis, failure to identify an infectious cause,
NONEROSIVE POLYARTHRITIS and the absence of evidence to support a diagnosis of SLE or
Nonerosive noninfectious polyarthritis in which a primary reason to suspect reactive polyarthritis (see Fig. 69.6). A
or underlying disease cannot be identified is referred to as CBC can be normal or inflammatory. Hyperglobulinemia