Objective—To compare gentamicin concentrations achieved in synovial fluid and joint tissues during IV administration and continuous intra-articular (IA) infusion of the tarsocrural joint in horses.
Animals—18 horses with clinically normal tarsocrural joints.
Procedure—Horses were assigned to 3 groups (6 horses/group) and administered gentamicin (6.6 mg/kg, IV, q 24 h for 4 days; group 1), a continuous IA infusion of gentamicin into the tarsocrural joint (50 mg/h for 73 hours; group 2), or both treatments (group 3). Serum, synovial fluid, and joint tissue samples were collected for measurement of gentamicin at various time points during and 73 hours after initiation of treatment. Gentamicin concentrations were compared by use of a Kruskal-Wallis ANOVA.
Results—At 73 hours, mean ± SE gentamicin concentrations in synovial fluid, synovial membrane, joint capsule, subchondral bone, and collateral ligament of group 1 horses were 11.5 ± 1.5 μg/mL, 21.1 ± 3.0 μg/g, 17.1 ± 1.4 μg/g, 9.8 ± 2.0 μg/g, and 5.9 ± 0.7 μg/g, respectively. Corresponding concentrations in group 2 horses were 458.7 ± 130.3 μg/mL, 496.8 ± 126.5 μg/g, 128.5 ± 74.2 μg/g, 99.4 ± 47.3 μg/g, and 13.5 ± 7.6 μg/g, respectively. Gentamicin concentrations in synovial fluid, synovial membrane, and joint capsule of group 1 horses were significantly lower than concentrations in those samples for horses in groups 2 and 3.
Conclusions and Clinical Relevance—Continuous IA infusion of gentamicin achieves higher drug concentrations in joint tissues of normal tarsocrural joints of horses, compared with concentrations after IV administration.
Objective—To determine whether joint lavage performed simultaneously with IV regional limb perfusion (IVRLP) reduces the effectiveness of IVRLP and to compare 2 types of tourniquets used for this procedure in horses.
Animals—11 adult horses.
Procedures—2 groups of 6 horses were tested by use of a pneumatic or an Esmarch tourniquet (1 horse was tested twice [once in each group]). Standing IVRLP with amikacin (500 mg) was performed for 30 minutes. Simultaneously, the metacarpophalangeal joint was lavaged with 2 L of lactated Ringer's solution and the egress fluids were collected. Samples of the distal interphalangeal joint synovial fluid and blood from the digital and jugular veins were collected at set time intervals. Amikacin concentrations in all fluids were determined via fluorescence polarization immunoassay.
Results—Less amikacin was measured in the systemic circulation with the Esmarch tourniquet than with the pneumatic tourniquet. Amikacin concentrations in the synovial fluid from the distal interphalangeal joints of the Esmarch tourniquet group ranged from 45.1 to 1,968 μg/mL and in the pneumatic tourniquet group ranged from 1.7 to 92.3 μg/mL after 30 minutes of IVRLP. Total loss of amikacin in the egress fluids from the joint lavage ranged from < 1.36 to 7.72 mg for the Esmarch tourniquet group and from < 1.20 to 1.75 mg for the pneumatic tourniquet group.
Conclusions and Clinical Relevance—On standing horses, IVRLP performed simultaneously with joint lavage resulted in negligible loss of amikacin in the egress lavage fluids. The Esmarch tourniquet was more effective in preventing loss of amikacin from the distal portion of the limb, easier to use, and less expensive than the pneumatic tourniquet.
Objective—To develop a method for continuous infusion
of gentamicin into the tarsocrural joint of horses,
to determine pharmacokinetics of gentamicin in synovial
fluid of the tarsocrural joint during continuous
infusion, and to evaluate effects of continuous infusion
of gentamicin on characteristics of the synovial
Animals—12 healthy adult horses.
Procedure—An infusion catheter consisting of flow
control tubing connected to a balloon infuser was
used. Gentamicin solution (100 mg/ml) was infused in
the right tarsocrural joint and balanced electrolyte
solution was infused in the left tarsocrural joint for 5
days. Synovial fluid and serum gentamicin concentrations
were measured by use of a fluorescence polarization
Results—17 of the 24 (71%) infusion catheters initially
placed functioned without complications for the entire
5-day infusion period. Median gentamicin concentration
in synovial fluid from treated joints during the 5-day infusion
period ranged from 287.5 to 982 μg/ml. Median
serum gentamicin concentration during this period
ranged from 2.31 to 2.59 μg/ml. Mean (± SD) elimination
half-life and total clearance of gentamicin from the
synovial fluid were 6.25 ± 1.01 hours and
1.52 ± 0.96 ml/min, respectively.
Conclusions and Clinical Relevance—An infusion
catheter can be used for continuous infusion of gentamicin
into the tarsocrural joints of horses for up to 5
days. At a gentamicin dosage of 0.17 ± 0.02 mg/kg/h,
continuous intra-articular infusion results in synovial
fluid gentamicin concentrations greater than 100
times the minimal inhibitory concentration reported
for common equine pathogens. (Am J Vet Res 2000;61:407–412)
Objective—To evaluate the management of equids undergoing cryptorchidectomy at a referral hospital.
Design—Retrospective case series.
Animals—604 client-owned equids.
Procedures—Medical records of all equids undergoing surgical treatment of cryptorchidism from 1977 to 2010 were retrospectively reviewed. Analyses of breed, location of retained testes, accuracy of palpation per rectum for determining the location of retained testes, surgical technique, and postoperative complications were performed.
Results—The most frequently affected breed was the Quarter Horse (282/604 [47%]), which was significantly overrepresented. Of the 604 equids, 90 (15%) had undergone previous surgical attempts at castration. Preoperative palpation per rectum was performed in 395/604 (65.4%) patients, and was accurate in predicting the location of the retained testes in 354/395 (89.6%). Surgeons were significantly more likely to be incorrect in determining the location of the retained testis by means of palpation per rectum in patients that had undergone a prior attempt at castration. For equids with abdominal cryptorchidism (360/604 [59.6%]), the most common surgical technique was noninvasive cryptorchidectomy (298/360 [82.8%]). In unilateral cryptorchids (521/604 [86.3%]), the 2 most common sites were left abdominal (184/521 [35.3%]) and right inguinal (148/521 [28.4%]). For bilateral retention (80/604 [13.2%]), abdominal cryptorchidism was most common (48/80 [60%]). Fever was present in 138/324 (43%) equids on the first day after surgery. Postoperative fever was not significantly associated with any variables evaluated. Including postoperative (≤ 24 hours) fever, 150 of 604 (25%) patients developed postoperative complications. Excluding postoperative fever, 18 of 604 (3%) patients developed major postoperative complications; complications in 10 of 604 patients were deemed surgically related, and 3 of 604 patients died.
Conclusions and Clinical Relevance—Results indicated that cryptorchidectomy in equids performed with a variety of surgical approaches was associated with minimal postoperative complications. A history of previous attempts at castration decreased the ability to accurately predict the location of the retained testis.
Objective—To determine clinical findings, complications, and outcome of septic synovitis in which continuous intrasynovial antimicrobial infusion (CIAI) was used for local antimicrobial delivery in horses.
Design—Retrospective case series.
Animals—22 adult horses and 9 foals (horses < 1 year of age).
Procedures—Records of horses with septic synovitis that had CIAI during treatment were reviewed. The association between clinical variables and whether horses performed their intended use following treatment was determined.
Results—42 synovial cavities were treated via CIAI. Twenty-nine cases were chronic (> 7 days) in nature, 15 had been refractory to standard treatments, and 13 synovial infections had associated osteomyelitis. Mean duration from infection to initiation of CIAI was 19.7 days, and mean duration of CIAI was 6.1 days. Temporary discharge from the catheter site at the time of removal was evident in 8 horses. Dysfunction of the infusion system occurred in 2 horses and was corrected during the course of treatment. No long-term complications were reported. Thirty-nine (93%) synovial infections in 29 (94%) horses were resolved. Twenty adult horses and 8 foals were discharged from the hospital, and 19 of 24 horses with long-term follow-up performed their intended use.
Conclusions and Clinical Relevance—CIAI was a useful adjunctive treatment for septic synovitis and allowed intrasynovial antimicrobial delivery into a variety of synovial cavities.
Objective—To determine the effects of a continuous
intra-articular infusion of gentamicin on the synovial
membrane and articular cartilage in the tarsocrural
joint of horses.
Animals—6 healthy adult horses.
Procedure—A balloon infusion system attached to a
catheter placed in the plantarolateral pouch of both
tarsocrural joints in each horse was used for continuous
gentamicin solution (GM) or balanced electrolyte
solution (BES) delivery for 5 days. Cartilage and synovial
membrane specimens were collected on day 5
from 3 horses and on day 14 from the remaining 3
horses. Both infused joints from each horse were
assessed, using gross evaluation and histologic scoring
Results—Significant differences in the histologic
scores of synovial membrane specimens between
the GM- and BES-treated joints at either 5 or 14 days
were not observed. Safranin-O-fast green staining
scores were similar between cartilage specimens
from GM- and BES-treated joints. Although the synovial
membrane histologic scores and safranin-O-fast
green staining scores improved from day 5 to 14, the
changes in scores were not significant. Loss of synovial
intimal cells from villi was found more commonly
in sections of synovial membrane from GM-treated
joints, compared with BES-treated joints.
Conclusions and Clinical Relevance—Continuous
infusion of GM into the tarsocrural joint of horses
does not have significant effects on histologic scores
of articular cartilage or synovial membrane, compared
with those infused with BES. Continuous infusion of
GM into the tarsocrural joint of horses for 5 days is an
acceptable method for the treatment of septic arthritis.
(Am J Vet Res 2002;63:683–687)
Objective—To determine synovial fluid gentamicin concentrations and evaluate adverse effects on the synovial membrane and articular cartilage of tarsocrural joints after implantation of a gentamicin-impregnated collagen sponge.
Animals—6 healthy adult mares.
Procedures—A purified bovine type I collagen sponge impregnated with 130 mg of gentamicin was implanted in the plantarolateral pouch of 1 tarsocrural joint of each horse, with the contralateral joint used as a sham-operated control joint. Gentamicin concentrations in synovial fluid and serum were determined for 120 hours after implantation by use of a fluorescence polarization immunoassay. Synovial membrane and cartilage specimens were collected 120 hours after implantation and evaluated histologically.
Results—Median peak synovial fluid gentamicin concentration of 168.9 μg/mL (range, 115.6 to 332 μg/mL) was achieved 3 hours after implantation. Synovial fluid gentamicin concentrations were < 4 μg/mL by 48 hours. Major histologic differences were not observed in the synovial membrane between control joints and joints implanted with gentamicin-impregnated sponges. Safranin-O fast green stain was not reduced in cartilage specimens obtained from treated joints, compared with those from control joints.
Conclusions and Clinical Relevance—Implantation of a gentamicin-impregnated collagen sponge in the tarsocrural joint of horses resulted in rapid release of gentamicin, with peak concentrations > 20 times the minimum inhibitory concentration reported for common pathogens that infect horses. A rapid decrease in synovial fluid gentamicin concentrations was detected. The purified bovine type I collagen sponges did not elicit substantial inflammation in the synovial membrane or cause mechanical trauma to the articular cartilage.
Objective—To determine outcome of horses in
which cutaneous masses were removed with a carbon
Procedure—Medical records of horses with 1 or
more cutaneous masses treated with a carbon dioxide
laser were examined. Follow-up information was
obtained through telephone interviews with owners
and referring veterinarians.
Results—Cutaneous masses were classified as sarcoids
(15 horses), neoplastic masses other than sarcoids
(squamous cell carcinoma ; fibroma ; and
melanoma ), and nonneoplastic masses (6).
Minimum follow-up time was 6 months. Five sarcoids
and 2 squamous cell carcinomas recurred. Seven
(21%) horses had complications associated with
dehiscence of wounds that had been closed primarily
or failure of wound healing because of recurrence of
the mass. Twenty-six (81%) owners were satisfied
with the cosmetic appearance following surgery.
Conclusion and Clinical Relevance—Results suggest
that a carbon dioxide laser may be effective for
treatment of cutaneous masses in horses. (J Am
Vet Med Assoc 2002;220:1192–1197)
Objective—To determine the extent to which a hydroxyapatite coating promotes pin stability in the third metacarpal bone during transfixation casting in horses.
Animals—14 adult horses.
Procedures—7 horses each were assigned to either an uncoated or hydroxyapatite-coated pin group. Three transcortical pins were placed in the third metacarpal bone of each horse and incorporated into a cast for 8 weeks. Insertion and extraction torque were measured, and torque reduction was calculated. Radiography was performed at 0, 4, and 8 weeks. Lameness evaluation was performed at 2, 4, 6, and 8 weeks. Bacteriologic culture of pins and pin holes was performed at pin removal.
Results—All horses used casts without major complication throughout the study. Insertion torque was higher in uncoated pins. There was no effect of group on extraction torque. Hydroxyapatite-coated pins had lower torque reduction. Five of 15 hydroxyapatite-coated pins maintained or increased stability, whereas all uncoated pins loosened. Pin hole radiolucency, lameness grades, and positive bacteriologic culture rates were not different between groups.
Conclusions and Clinical Relevance—Hydroxyapatite coating increased pin stability within the third metacarpal bone of horses during 8 weeks of transfixation casting but did not improve pin performance on clinical assessments. Clinical use of hydroxyapatite-coated transfixation pins may result in greater pin stability; however, further research is necessary to improve the consistency of pin osteointegration and elucidate whether clinical benefits will ultimately result from this approach in horses.