Page 1347 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

1322 CHAPTER 13

VetBooks.ir are present. Confirmation of an infectious synovial Eliminating the causative organism(s)
The organisms involved in synovial infections are
process is obtained through cytological evaluation
of synovial fluid. A previous intra-articular ste-
roid injection (up to 3 weeks) is a risk factor for the generally well known. Post-injection synovial infec-
tions are most commonly caused by Staphyloccocus
development of a septic joint and may also alter the aureus and post-traumatic infections by coliforms.
expected cytological findings. The interpretation of This may not always be the case, and the sensitivity
synovial fluid results should include assessment of patterns vary depending on geographical location
protein content, differential cell count and cellular and bacterial strain. Failure to obtain a positive cul-
morphological characteristics. The presence of 75% ture, which can happen in up to 50% of cases, should
or more neutrophils or toxic changes to neutrophils, not preclude an educated guess as to what antibiotics
with a compatible medical history, should be consid- may be most effective. Elimination of bacteria from a
ered evidence of synovial sepsis until proven other- synovial cavity is achieved by a combination of anti-
wise. Measurement of serum and synovial levels of microbial therapy and synovial lavage. Synovial lavage
serum amyloid A (SAA) has been used to confirm is best performed by arthroscopy, although where
the presence of sepsis and SAA plasma concentra- cost is an issue it can be carried out by a through-
tion can also be used to monitor response to treat- and-through method using needles and drip sets. In
ment. If any doubt exists pertaining to the diagnosis, refractory cases, open joint drainage may be neces-
the clinician should assume that a synovial cavity sary (Fig. 13.40). Currently, the most widely used
is infected and start treatment promptly. Failure to antibiotic combination is either penicillin or a third-
treat a synovial infection promptly may jeopardise generation cephalosporin (e.g. ceftiofur, ceftazidime),
the final outcome. together with an aminoglycoside (e.g. amikacin).
The treatment of infectious synovitis is aimed Systemic and local/regional administration of antibi-
at different areas: (1) eliminating the causative otics in cases of synovial sepsis has become a routine
organism(s); (2) diminishing the inflammatory treatment. Local/regional antibiotics are very effec-
process and providing analgesia; (3) restoring tive in eliminating bacterial infection from synovial
synovial homeostasis; and (4) rehabilitating the structures and should be included as a treatment
horse. strategy in these cases (Fig. 13.41, Table 13.6).

13.40A 13.40B

Fig. 13.40 This horse fell on the road when at exercise, lacerated the dorsal aspect of the right carpus
and subsequently had synovial fluid draining from the wound. Under general anaesthesia and after surgical
debridement/exploration of the wound, a defect in the dorsolateral aspect of the antebrachiocarpal joint was
detected. This allowed an arthroscope to be inserted into the joint for exploration and lavage (A). After the joint
was lavaged, the tendon sheath of the extensor carpi radialis was also lavaged, as this had been involved in the
trauma and was contaminated (B).