Septic Arthritis
(Infective arthritis) |  |
| Etiology and Epidemiology: |
| Septic or infective arthritis results from sequestration of bacterial infection in a joint. Infection of a joint develops in 3 main ways: 1) hematogenous infection, which is common in foals, calves, and lambs (commonly referred to as navel ill); 2) traumatic injury with local introduction of infection; 3) iatrogenic infection associated with joint injection or surgery (usually in horses). Navel ill is only one example of a hematogenous route of infection, which can also be
gained from GI or pulmonary sources. |
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| Clinical Findings and Diagnosis: |
|
Septic arthritis is usually characterized by severe lameness and distention of the joint with cloudy, turbid synovial fluid that contains >30,000 WBC/mm3 and a total protein level of >4 g/dL. In foals, hematogenous osteomyelitis often accompanies septic arthritis. Septic arthritis in foals has been classified into type S (septic joint only), type P (involving osteomyelitis of the adjacent growth plate as
well), or type E (involving osteomyelitis of the epiphyseal and subchondral bone). Various organisms may be involved. In young lambs,
Actinobacillus
seminis
causes polyarthritis, as do
Chlamydophila (Chlamydia)
psittaci
and
Erysipelothrix
insidiosa
. The latter can follow docking, castration, or navel infection. Viruses and mycoplasma may also be etiologic agents in food-producing animals. In mature goats, caprine arthritis and encephalitis virus (
Caprine Arthritis and Encephalitis: Introduction) is an important cause of infective arthritis. In young goats,
C
psittaci
and
Mycoplasma
mycoides
are frequent causes. Bacterial (including
Mycoplasma
) arthritides are seen in young pigs. In newborn pigs, septic arthritis usually is due to intrauterine or navel infection with
Escherichia
coli
,
Corynebacterium
,
Streptococcus
, or
Staphylococcus
spp
. Control is best directed toward reducing the possibility of infection from the environment. Older pigs sometimes develop arthritis as a sequela of infection with
Haemophilus
,
Erysipelothrix
, or
Mycoplasma
spp
. Although diagnosis in the early stages is not difficult, the more chronic stages can be confused with articular lesions produced by dietary hypervitaminosis A. |
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| Treatment: |
| Septic arthritis requires prompt treatment to avoid irreparable damage. Systemic broad-spectrum antibiotics are indicated; the initial choice is based on the most likely pathogen but is subject to change based on culture and sensitivity tests. Systemic antibiotic treatment is often combined with intra-articular antibiotics (to achieve more effective sterilization of the joint) and other local therapy, including joint lavage (initially) and arthroscopic debridement and drainage.
Adjunctive treatment with NSAID (eg, phenylbutazone) is also done. The effectiveness of treatment is monitored carefully with clinical signs and repeat synovial fluid analyses. |
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