Septic Arthritis in Goats

Several joints can be involved in joint-ill, a nonspecific bacterial infection typically originating from hematogenous transmission of environmental organisms. Bacteria that have been incriminated include Trueperella pyogenes, staphylococci, streptococci, Corynebacterium spp, Actinomyces spp,Erysipelothrix rhusiopathiae, and Escherichia coli.

Environmental bacteria gain entry to the neonate’s circulation, usually via omphalitis. Other methods of entry include contamination of breaks in the skin or via the gastrointestinal or respiratory tract. Predisposing factors include lack of routine dipping of the umbilical cord; inadequate passive transfer; poor sanitation in the kidding pens; or does kidding in overcrowded, dirty conditions. E rhusiopathiae are soil-living bacteria that may persist on farms or in pens used by sheep or pigs. Mycoplasma infection is also a differential diagnosis for polyarthritis in goat kids.

With septic arthritis, one or more joints are hot, swollen, and painful. Often, the affected limbs cannot bear weight, and kids with more than one leg affected may be unable to stand. The more commonly affected joints include the carpus, shoulder, hock, and stifle joints. There may be a fever, but typically the kid remains alert and active with no reduction in appetite. Sometimes omphalitis is active or there is an abscess of the umbilical structures; however, infection may be historical and there may be no detectable abnormalities.

If the condition becomes chronic, the limbs are stiff, some joints may be ankylosed, and overall growth is poor.

The WBC count may be increased with or without a left shift. Radiographs may reveal only mild soft-tissue swelling or lysis and reaction of subchondral bone. Ultrasonographic examination often demonstrates increased synovial fluid volume and echogenicity, and associated tendon sheaths may also show evidence of infection.

Definitive diagnosis is made with arthrocentesis. Synovial fluid may be cloudy to completely opaque, watery, malodorous, or fibrinous. Grossly normal synovial fluid may still be septic, and cell counts and cytologic evaluation should be pursued. Neutrophils dominate the cell population in septic arthritis, and intracellular bacteria may be present. Clear or cloudy joint fluid with many mononuclear cells suggests caprine arthritis and encephalitis virus.

In cases where treatment will be pursued, bacteriologic culture and antimicrobial susceptibility testing is strongly recommended. Results of no growth on bacterial cultures are relatively common, even in septic arthritis, due to low bacterial load or recent antimicrobial administration.

To be successful, treatment of septic arthritis must be provided early, and when possible, antimicrobial selection should be based on results of bacteriologic culture and antimicrobial susceptibility testing. The source of bacteremia should also be resolved, and removal of abscessed or chronically infected umbilical structures must be performed if no relapse is to be expected. Treatment with parenteral antimicrobials that are likely to reach therapeutic concentrations in the synovial fluid (eg, florfenicol and macrolides) may resolve early or mild cases. In valuable animals, joint lavage with saline (0.9% NaCl) solution, intra-articular injection of antimicrobials, and regional limb perfusion may improve likelihood of success.

Some animals may be so severely affected that arthrotomy and debridement of infected bone and cartilage may be required. Even with prompt and aggressive treatment, prognosis remains guarded, especially for animals with multiple joints affected, subchondral bone infection, or exuberant fibrin production in the joint.

In commercial herds, treating severely affected kids may not be economically justified, and euthanasia should be considered. Animals that recover may have decreased growth and be unthrifty compared to their peers, and arthritis is more likely to develop later in life. Unsuccessfully treated or untreated animals will have permanent damage to the joint, resulting in contracture and inability to use the limb.

For control of septic arthritis, hygiene at parturition is essential, including a clean, dry kidding area.

The umbilical cords of newborn kids should be dipped in 7% tincture of iodine or another antiseptic solution several times over the first 24–48 hours after birth. Adequate intake of colostrum is essential, and smaller or weaker kids should be assisted to nurse or provided with banked colostrum or colostrum replacer. Umbilical infections and any other perinatal illnesses should be addressed promptly.