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.
Objective—To determine prevalence and radiologic
and histologic appearance of vesicourachal diverticula
in dogs without clinical signs of urinary tract disease.
Animals—50 dogs between 4 months and 17 years
old representing 22 breeds that had been euthanatized
for unrelated reasons; none of the dogs had a
history or clinical signs of urinary tract disease.
Procedure—Retrograde positive-contrast radiography
was performed, and radiographs were examined for
macroscopic diverticula. Necropsy specimens from
the urinary bladder vertex were examined by means
of light microscopy for diverticula and signs of inflammation.
Results—17 of the 50 (34%) dogs had vesicourachal
diverticula, and 1 additional dog had a urachal cyst.
Fifteen of the 17 diverticula were macroscopic; surface
area of the diverticulum could be measured radiographically
in 13 of these dogs and ranged from 1 to
90 mm2. The remaining 2 diverticula were microscopic.
Sixteen diverticula were intramural and 1 was
extramural. Light microscopic signs of bladder wall
inflammation could be detected in 5 dogs, 4 of which
had macroscopic diverticula.
Conclusions and Clinical Relevance—Results suggest
that a high percentage of dogs without clinical
signs of urinary tract disease may have vesicourethral
diverticula. Further studies are needed to determine
the clinical relevance of vesicourethral diverticula in
dogs. (J Am Vet Med Assoc 2005;226:383–386)
OBJECTIVE To investigate the effect of lipopolysaccharide (LPS) on type VII collagen– cleaving matrix metalloproteinases (MMPs) in the lamellar tissue of extracorporeally perfused equine limbs.
SAMPLE 10 right forelimbs and 3 left forelimbs collected from 10 adult horses after slaughter at a licensed abattoir.
PROCEDURES Extracorporeal perfusion of the isolated equine limbs was performed for 10 hours under physiologic conditions (control-perfused limbs; n = 5) and with the addition of 80 ng of LPS/L of perfusate (LPS-perfused limbs; 5). Lamellar tissue specimens were then collected from the dorsal aspect of the hooves. Additionally, corresponding control specimens were collected from the 3 nonperfused left forelimbs. Immunohistochemical analysis was performed on paraffin-embedded tissue blocks with antibodies against total (latent and active) MMP-1, MMP-2, MMP-8, and MMP-9 as well as antibody against active MMP-9. Intensity of immunohistochemical staining was scored, and stain distribution in the lamellar tissue was noted.
RESULTS Staining intensity of total and active MMP-9 was significantly increased in LPS-perfused versus control-perfused limbs. No such difference was identified for MMP-1, MMP-2, and MMP-8.
CONCLUSIONS AND CLINICAL RELEVANCE Of the 4 MMPs that are capable of degrading type VII collagen, MMP-9 was the only one for which production increased in the lamellar tissue of isolated equine limbs perfused with versus without a clinically relevant concentration of LPS. These results suggested that MMP-9 may be involved in initiation of pathological changes in lamellar tissue in endotoxin-induced laminitis, whereas MMP-1, MMP-2, and MMP-8 may be less relevant.