Objective—To determine clinical findings in and outcome
of horses with fractures of the second or fourth
metacarpal or metatarsal bone that underwent segmental
ostectomy, leaving the proximal and distal portions
of the bone undisturbed.
Design—Retrospective case series.
Procedures—Medical records were reviewed, and
information on signalment, affected bone, lesion
type, surgical procedure, amount of bone removed,
and surgical and postsurgical complications was
obtained. Follow-up information was obtained
through telephone conversations with owners, trainers,
and referring veterinarians.
Results—One horse had a fracture involving the distal
third of the second metacarpal bone; 13 had fractures
involving the middle third of the second
metacarpal bone (n = 4), fourth metacarpal bone (5),
or fourth metatarsal bone (4); and 3 had fractures
involving the proximal third of the second (2) or fourth
(1) metacarpal bone. Affected portions of the bones
were surgically resected, leaving the proximal and distal
portions undisturbed. All horses returned to previous
performance levels without evidence of lameness.
Cosmetic results were good to excellent.
Conclusions and Clinical Relevance—Results suggest
that horses with a complicated injury of the proximal,
middle, or distal portion of the second or fourth
metacarpal or metatarsal bone may be successfully
treated by means of segmental ostectomy of the
abnormal portion of the bone. (J Am Vet Med Assoc
Objective—To determine hyaluronan concentrations in peritoneal fluid from healthy horses and horses with sudden signs of severe abdominal pain and to identify the cellular sources of hyaluronan within the peritoneal cavity.
Animals—7 client-owned horses that were evaluated for sudden signs of severe abdominal pain, 6 healthy teaching horses, and 13 euthanized horses (11 with no abdominal disease and 2 that had undergone abdominal surgery 2 weeks previously for a different study).
Procedures—Abdominal fluid was collected from the client-owned and teaching horses. Hyaluronan concentrations were determined with an ELISA. Equine mesothelial cells were aseptically harvested from euthanized horses immediately after euthanasia, cultured, and processed for western blot immunoassays to detect expression of the following mesothelial cell markers: cytokeratins 8 and 18, vimentin, calretinin, mesothelin, and CD44. A reverse transcriptase–PCR assay was used to detect genetic expression of hyaluronan synthase-2 (HAS-2) from cultured and native equine tissue.
Results—The mean ± SD abdominal hyaluronan concentration in peritoneal fluid from horses with signs of abdominal pain (1,203.3 ± 46.3 ng/mL) was significantly greater than that in healthy horses (228.4 ± 167.3 ng/mL). Harvested cells were maintained, and immunoblotting analyses confirmed expression of the mesothelial markers. Gene expression of HAS-2 from cultured mesothelial cells and fibroblasts was confirmed.
Conclusions and Clinical Relevance—Peritoneal hyaluronan concentration was much higher in horses with severe abdominal pain than in healthy horses. Cultured equine mesothelial cells and fibroblasts can produce hyaluronan through HAS-2. Future investigation should focus on establishing the effect of exogenous hyaluronan administration on mesothelial cell function in horses with abdominal disease.
Objective—To determine the response of cortical bone to a multicomponent and nanostructural polymeric matrix as a drug delivery system for enhancing bone healing.
Animals—20 healthy adult crossbred goats.
Procedures—A 3.5-mm-diameter unicortical defect was created in each tibia (day 0), and goats (4 goats/group) were treated as follows: not treated (control group), grafted with the matrix, grafted with antimicrobial (tigecycline and tobramycin)–impregnated matrix, grafted with recombinant human bone morphogenetic protein type 2 (rhBMP-2)–impregnated matrix, or grafted with antimicrobial- and rhBMP-2–impregnated matrix. Elution kinetics of antimicrobials was monitored through plasma concentrations. Bone response was assessed with radiographic scoring (days 1 and 30) and dual-energy x-ray absorptiometry (days 1, 14, and 30). Goats were euthanized on day 30, and histomorphologic analysis was performed. Categorical variables were analyzed with a generalized linear model, and continuous variables were analyzed with an ANOVA.
Results—Plasma antimicrobial concentrations indicated continued release throughout the study. Radiography and dual-energy x-ray absorptiometry did not reveal significant differences among treatments on day 30. Periosteal reactions were significantly greater surrounding bone defects grafted with rhBMP-2–impregnated matrix than those not treated or grafted with matrix or with antimicrobial-impregnated matrix; periosteal reactions were similar in bone defects grafted with rhBMP-2–impregnated matrix and antimicrobial- and rhBMP-2–impregnated matrix.
Conclusions and Clinical Relevance—The matrix served as an antimicrobial delivery system and stimulated bone proliferation when rhBMP-2 was present. Antimicrobial and rhBMP-2 can be used concurrently, but the presence of antimicrobials may affect the performance of rhBMP-2.
Objective—To determine microradiographic appearance,
bone histomorphometry, and mineral density of
the long bones of the metacarpophalangeal joint in
horses after immobilization followed by remobilization.
Animals—5 healthy horses.
Procedure—One forelimb of each horse was immobilized
in a fiberglass cast for 7 weeks, followed by 8
weeks of increasing exercise. Calcein and oxytetracycline
were administered IV during the immobilization
and exercise phases, respectively, for bone labeling
and analysis after euthanasia. Sagittal sections of
metacarpal bones and proximal phalanges were
examined via radiography, dual energy x-ray absorptiometry,
histomorphometry, and bone label analysis.
Results—Radiography revealed loss of bone mineral
opacity in the subarticular regions of the immobilized
metacarpal bones and phalanges and subchondral
lesions in metacarpal bones in 2 horses. In phalanges,
a significant decrease in subarticular volumetric bone
mineral density was detected. There was significantly
less bone volume and calcein-labeled bone surface
and more vascular volume and oxytetracycline-labeled
bone surface in immobilized phalanges, compared
with contralateral phalanges.
Conclusions and Clinical Relevance—Eight weeks
of exercise after single-limb immobilization is insufficient
for recovery of volumetric bone mineral density.
During immobilization and remobilization, the subchondral
and trabecular bone appear to be actively
remodeling. (Am J Vet Res 2002;63:276–281)
Objective—To evaluate clinical effects of immobilization
followed by remobilization and exercise on the
metacarpophalangeal joint (MPJ) in horses.
Animals—5 healthy horses.
Procedure—After lameness, radiographic, and force
plate examinations to determine musculoskeletal
health, 1 forelimb of each horse was immobilized in a
fiberglass cast for 7 weeks, followed by cast removal
and increasing amounts of exercise, beginning with
hand-walking and ending with treadmill exercise.
Lameness examination, arthrocentesis of both MPJ,
single-emulsion radiographic examination, nuclear
scintigraphic examination, ground-reaction force-plate
analysis, and computed tomographic examination
were done at various times during the study.
Results—All horses were lame in the immobilized
MPJ after cast removal; lameness improved slightly
with exercise. Force plate analysis revealed a significant
difference in peak forces between immobilized
and contralateral limbs 2 weeks after cast removal.
Range of motion of the immobilized MPJ was significantly
decreased, and joint circumference was significantly
increased, compared with baseline values,
during the exercise period. Osteopenia was subjectively
detected in the immobilized limbs. Significant
increase in the uptake of radionucleotide within
bones of the immobilized MPJ after cast removal and
at the end of the study were detected. Loss of mineral
opacity, increased vascular channels in the subchondral
bone, and thickening within the soft tissues
of the immobilized MPJ were detected.
Conclusions and Clinical Relevance—Results indicate
that 8 weeks of enforced exercise after 7 weeks
of joint immobilization did not restore joint function or
values for various joint measurements determined
prior to immobilization. (Am J Vet Res 2002;63:282–288)
Objective—To determine whether ether-a-go-go
(ERG) potassium channels are expressed in equine
gastrointestinal smooth muscle, whether ERG channel
antagonists affect jejunal muscle contraction in
vitro, and whether plasma cisapride concentrations in
horses administered treatment for postoperative ileus
(POI) are consistent with ERG channels as drug targets.
Sample Population—Samples of intestinal smooth
muscle obtained from 8 horses free of gastrointestinal
tract disease and plasma samples obtained from
3 horses administered cisapride for treatment of POI.
Procedure—Membranes were prepared from the
seromuscular layer of the duodenum, jejunum, ileum,
cecum, large colon, and small colon. Immunoblotting
was used to identify the ERG channel protein.
Isolated jejunal muscle strips were used for isometric
stress response to ERG channel blockers that included
E-4031, MK-499, clofilium, and cisapride. Plasma
concentrations of cisapride were determined in 3
horses administered cisapride for treatment of POI
after small intestinal surgery.
Results—Immunoblotting identified ERG protein in all
analyzed segments of the intestinal tract in all horses.
The selective ERG antagonist E-4031 caused a concentration-
dependent increase in jejunal contraction.
Clofilium, MK-499, and cisapride also increased jejunal
contraction at concentrations consistent with ERG
channel block; effects of E-4031 and cisapride were
not additive. Peak plasma cisapride concentrations in
treated horses were consistent with ERG block as a
mechanism of drug action.
Conclusions and Clinical Relevance—The ERG
potassium channels modulate motility of intestinal
muscles in horses and may be a target for drugs. This
finding may influence development of new prokinetic
agents and impact treatment of horses with POI.
(Am J Vet Res 2003;64:267–272)
Objective—To determine history, physical and diagnostic
examination findings, medical treatment, and
outcome of horses with open injuries to the digital
flexor tendon sheath treated with the assistance of
Procedure—Medical records of 20 horses with open
injuries to the digital flexor tendon sheath were
reviewed. Signalment, history, physical and diagnostic
examination results, bacteriologic culture and susceptibility
testing results, surgical and medical treatments,
and follow-up examination results were determined.
Outcome was determined by use of telephone
interview or physical examination.
Results—All horses were treated with tenoscopicassisted
lavage and débridement. Eighteen horses
survived, and 2 were euthanatized during treatment.
All horses were either grade-4 or grade-5 lame before
treatment. Ten horses returned to previous use. Four
horses were considered mildly lame and in athletic
use. Three horses were considered mechanically
lame and are in use with reduced expectations. One
horse was lost to follow-up after being sold. One
horse was euthanatized for financial reasons and 1
because of complications from regional sepsis.
Conclusions and Clinical Relevance—Tenoscopy
appears to be a useful modality in the treatment of
open injury to the digital flexor tendon sheath in horses.
Direct viewing, guided débridement, and targeted
large-volume lavage are advantages obtained with
intrathecal arthroscopy. Tenoscopy, when combined
with antimicrobial and anti-inflammatory treatment,
appears to offer a good chance of survival for affected
horses. (J Am Vet Med Assoc 2002;220:1823–1827)