Objective—To study chondrotoxic effects of
enrofloxacin (ENR) and ciprofloxacin hydrochloride
(CFX) on canine and equine articular chondrocytes in
culture and to compare the effects with that of cultivation
in Mg2+-free medium.
Sample Population—Chondrocytes from articular
cartilage of 4- and 6 -month old dogs and 2- to 4- year-old
Procedure—Chondrocytes were cultivated with 10,
40, 80, and 160 μg of CFX/ml, 10, 50, 100, and 150 μg
of ENR/ml, or in Mg2+-free medium. A live-to-dead
test was performed to test cytotoxic effects.
Morphologic changes were evaluated by electron
microscopy. An attachment assay was used to test
the ability of chondrocytes to adhere to collagen type-
II coated-chamber slides in the presence of CFX and
with Mg2+-free medium.
Results—Chondrocytes cultivated in quinolone-supplemented
medium or Mg2+-free medium had a
decreased ability to adhere to culture dishes. Cell
shape and the actin and vimentin cytoskeleton
changed in a concentration-dependent manner. These
effects were not species-specific and developed with
both quinolones. On day 1 of culture, adhesion of
chondrocytes to collagen type II was reduced to 70
and 45% of control values in the CFX treatment and
Mg2+-free treatment groups, respectively. On day 5 of
culture, adhesion of chondrocytes was reduced to 45
and 40% of control values in the CFX treatment and
Mg2+-free treatment groups, respectively.
Conclusion and Clinical Relevance—In vitro, chondrotoxic
effects of quinolones appear to be the result
of irregular integrin signaling and subsequent cellular
changes. Drug concentrations leading to morphologic
changes in vitro may be achieved in articular cartilage
in vivo. (Am J Vet Res 2001;62:704–708)
Objective—To describe the anatomic and histologic features of the collateral ligaments (CLs) of the metacarpophalangeal (MCP) and metatarsophalangeal (MTP) joints in cadaveric limbs obtained from nonlame horses and to compare the histologic findings with the ultrasonographic appearance of the CLs.
Sample—Medial and lateral CLs of the MCP and MTP joints of 28 limbs (16 forelimbs and 12 hind limbs) from 9 adult nonlame horses euthanized for reasons unrelated to the study.
Procedures—26 limbs of 8 horses were examined by ultrasonography immediately after euthanasia. Postmortem gross and histologic examinations were performed for all 28 limbs. Histologic and ultrasonographic images were graded and compared.
Results—Ultrasonographically, the mean ± SD depth and width of the superficial CL were 5.1 ± 0.7 mm and 20.5 ± 1.7 mm, respectively. On histologic examination, only 125 of 319 (39%) specimens obtained from 56 medial and lateral CLs appeared normal. Histopathologic findings varied from mild changes in cellular density and collagen fiber orientation to severe fibrocartilaginous metaplasia. The degree of CL lesion severity increased distally, and the lateral CL was affected more frequently than was the medial CL. Ultrasonographically detectable abnormalities were not correlated with the histologic findings.
Conclusions and Clinical Relevance—In horses, histologic abnormalities within the CLs of the MCP and MTP joints may be an adaptive response to joint hyperextension and compression and might predispose horses to desmopathy and ligament failure in the event of trauma. Ultrasonography did not detect morphologic changes of the CL matrix. For an accurate diagnosis of subclinical lesions, more sensitive imaging techniques (eg, MRI) should be considered.