Bryan T. Torres

Effects of meloxicam on plasma iohexol clearance as a marker of glomerular filtration rate in conscious healthy cats

OBJECTIVE To investigate the effect of therapeutic dosages of meloxicam on the plasma clearance of iohexol in healthy, euvolemic, conscious cats fed a sodium-replete diet. ANIMALS 6 healthy adult neutered male cats. PROCEDURES For each treatment period in a masked, randomized, crossover study, cats were administered either no treatment or meloxicam. Iohexol clearance studies were performed before the treatment period began (baseline) and on the final day of the treatment period. Iohexol concentrations were determined by use of a high-performance liquid chromatography assay, and plasma iohexol clearance as a marker of glomerular filtration rate was calculated by use of a 1-compartment model. RESULTS No significant treatment effect was detected. Mean +/- SE iohexol clearance for cats administered meloxicam (3.31 +/- 0.27 mL/min/kg) was not significantly different from mean baseline value for the meloxicam treatment period (3.07 +/- 0.32 mL/min/kg). CONCLUSIONS AND CLINICAL RELEVANCE In this study, short-term meloxicam administration did not measurably alter the glomerular filtration rate as assessed via plasma clearance of iohexol. This suggests that renal prostaglandins in cats did not have a measurable effect on glomerular filtration rates in healthy, euvolemic, conscious states as determined on the basis of methods used in this study.

Effects of Firocoxib and Tepoxalin on Healing in a Canine Gastric Mucosal Injury Model

BACKGROUND Little is known about the effect of dual cyclooxygenase (COX) and lipoxygenase inhibition on canine gastric mucosal healing. OBJECTIVE This study compares the effects of putative dual COX and 5-lipoxygenase inhibition with that of COX-2 selective inhibition on gastric mucosal lesion healing in dogs. ANIMALS Six normal adult mixed-breed research dogs. METHODS Gastric body and pyloric lesions were induced by endoscopic biopsy. Dogs were treated with tepoxalin, firocoxib, or placebo for 7 days in a randomized 3-way crossover study design. Healing was evaluated on days 2, 4, and 7 of treatment by endoscopic lesion scoring. Eicosanoid concentrations in plasma and at the lesion margins were determined on days 2, 4, and 7. Repeated measures analyses were performed. All hypothesis tests were 2-sided with P < .05. Multiple comparisons were adjusted using Tukeys test. RESULTS Significant treatment differences were noted in the pyloric lesion area measurements. Overall, the firocoxib group had larger lesions than the placebo (P= .0469) or tepoxalin (P= .0089) groups. Despite larger pyloric lesions in the firocoxib group, mucosal prostaglandin production did not differ significantly from placebo. In contrast, the tepoxalin group had significantly lower pyloric mucosal prostaglandin production compared with the firocoxib (P < .0001) or the placebo (P < .0001) groups but pyloric lesions were not significantly larger than those of the placebo group (P= .7829). CONCLUSION COX-2 inhibition by firocoxib slowed wound healing by a mechanism independent of prostaglandin synthesis. Suppression of mucosal prostaglandin production by tepoxalin did not alter mucosal lesion healing compared with placebo.

Comparison of Canine Stifle Kinematic Data Collected with Three Different Targeting Models

OBJECTIVE To model the kinematics of the canine stifle in 3 dimensions using the Joint Coordinate System (JCS) and compare the JCS method with linear and segmental models. STUDY DESIGN In vivo biomechanical study. ANIMALS Normal adult mixed breed dogs (n=6). METHODS Dogs had 10 retroreflective markers affixed to the skin on the right pelvic limb. Dogs were walked and trotted 5 times through the calibrated space and the procedure was repeated 5 days later. Sagittal flexion and extension angle waveforms acquired during each trial with all 3 models (JCS, Linear, and Segmental) were produced simultaneously during each gait. The JCS method provided additional internal/external and abduction/adduction angles. Comparison of sagittal flexion and extension angle waveforms was performed with generalized indicator function analysis (GIFA) and Fourier analysis. A normalization procedure was performed. RESULTS Each model provided consistent equivalent sagittal flexion-extension data. The JCS provided consistent additional internal/external and abduction/adduction. Sagittal waveform differences were found between methods and testing days for each dog at a walk and a trot with both GIFA and Fourier analysis. After normalization, differences were less with Fourier analysis and were unaltered with GIFA. CONCLUSIONS Whereas all methods produced similar flexion-extension waveforms, JCS provided additional valuable data. CLINICAL RELEVANCE The JCS model provided sagittal plane flexion/extension data as well as internal/external rotation and abduction/adduction data.

Evaluation of a three-dimensional kinematic model for canine gait analysis

OBJECTIVE To evaluate a 3-D kinematic model of the hind limb developed by use of a joint coordinate system in dogs. ANIMALS 6 clinically normal adult mixed-breed dogs. PROCEDURES 17 retroreflective markers were affixed to the skin on the right hind limb of each dog. Eight infrared cameras were arranged around a gait platform to record marker locations as dogs were recorded moving through the calibrated space 5 times during a walk and trot at velocities of 0.9 to 1.2 m/s and 1.7 to 2.1 m/s, respectively. Local and global coordinate systems were established, and a segmental rigid-body model of the canine hind limb was produced. Dynamic 3-D joint kinematic measurements were collected for the hip, stifle, and tarsal joints. RESULTS Sagittal (flexion-extension), transverse (internal-external rotation), and frontal (abduction-adduction) plane kinematic measurements were acquired during each trial for the hip, stifle, and tarsal joints. CONCLUSIONS AND CLINICAL RELEVANCE The joint coordinate system allowed acquisition of 3-D kinematic measurements of the hip, stifle, and tarsal joints of the canine hind limb. Methods were described to model 3-D joint motion of the canine hind limb.

Comparison of overground and treadmill-based gaits of dogs

OBJECTIVE To compare overground and treadmill-based gaits of dogs. ANIMALS 5 clinically normal adult mixed-breed dogs. PROCEDURES To obtain dynamic gait data, 30 retroreflective markers were affixed bilaterally to specific regions of the hind limbs and pelvis of each dog. For each dog, 3-D joint motion data (sagittal [flexion and extension], transverse [internal and external rotation], and frontal [abduction and adduction] planes of motion) for the hip, femorotibial, and tarsal joints were acquired during walking and trotting through a calibrated testing space overground or on a treadmill. Comparison of data was performed via generalized indicator function analysis and Fourier analysis. RESULTS Both overground and treadmill-based gaits produced similar waveforms in all planes of motion. Fourier analysis revealed no difference between overground and treadmill-based gaits in the sagittal plane of motion; however, small differences were detected between overground and treadmill-based gaits in the other 2 planes of motion. Additionally, femorotibial joint motion during walking did not differ among planes of motion. Generalized indicator function analysis was able to detect differences between overground and treadmill-based gait waveforms in all planes of motion for all joints during walking and trotting. CONCLUSIONS AND CLINICAL RELEVANCE In dogs, overground and treadmill-based gaits produced similar waveform shapes. Of the 3 planes of motion evaluated, only sagittal plane kinematic gait data were unaffected by mode of ambulation as determined via Fourier analysis. Sagittal kinematic gait data collected from dogs during overground or treadmill-based ambulation were comparable. However, analysis methods may affect data comparisons.

The effect of marker location variability on noninvasive canine stifle kinematics.

OBJECTIVE Evaluate the effect of marker placement on kinematics of the canine stifle in 3 distinct hindlimb models. STUDY DESIGN In vivo biomechanical study. ANIMALS Normal adult mixed-breed dogs (n=5). METHODS Ten retroreflective markers were affixed to the skin on the right rear leg of each dog to establish normal stifle kinematics. Four additional markers were placed around the greater trochanter (GT), 2 m cranial, caudal, dorsal, and ventral to evaluate single marker placement variability on kinematic model data. Dogs were walked and trotted 5 times through the calibrated space. Sagittal flexion and extension angle waveforms were acquired during each trial with 3 models that were produced simultaneously during each gait. The GT marker was reassigned to 1 of the 4 additional locations (cranial, caudal, dorsal, and ventral) to alter the kinematic model. Comparison of sagittal flexion and extension angle waveforms was performed with Generalized Indicator Function Analysis. RESULTS Each model provided consistent equivalent sagittal flexion-extension data. Analysis revealed statistically significant differences between all GT locations. The differences were greatest in the cranial and caudal locations for all models. CONCLUSIONS Deviation of the GT marker in the cranial/caudal direction from an anatomically normal position produces a greater degree of difference than deviation in a dorsal/ventral direction.

Revision of cemented total hip arthroplasty with cementless components in three dogs.

OBJECTIVE To report revision of cemented total hip arthroplasty failure with cementless components in 3 dogs. STUDY DESIGN Clinical case reports. ANIMALS Dogs with total hip arthroplasty failure (n=3). METHODS Cementless total hip arthroplasty revision was performed in 3 dogs with previously cemented femoral and acetabular components. All dogs required revision of the femoral component and 1 dog also required revision of the acetabular component. RESULTS Revisions resulted in a stable functional prosthesis with successful bone integration. CONCLUSIONS Use of cementless components may be a viable option for revision of loosened cemented prosthesis after explantation of failed cemented canine total hip replacements. CLINICAL RELEVANCE Failed canine-cemented total hip arthroplasties can be successfully revised with cementless components.

Successful Cementless Cup Reimplantation Using Cortical Bone Graft Augmentation after an Acetabular Fracture and Cup Displacement

OBJECTIVE To report repair of a periprosthetic acetabular fracture with concurrent component displacement after cementless total hip arthroplasty (THA). STUDY DESIGN Clinical case report. ANIMALS Dog (n=1) with an acetabular fracture after THA. METHODS Acetabular repair was performed on a highly comminuted periprosthetic acetabular fracture after cementless THA. A bulk, structural corticocancellous autograft from the ipsilateral ilial wing was used for repair and reconstruction of the dorsal acetabular wall before reimplantation of a cementless acetabular component. RESULTS Repair of a periprosthetic acetabular fracture with a bulk structural autograft was successful in reconstruction of the dorsal acetabular wall and in reestablishing a stable, functional cementless THA acetabular prosthesis. CONCLUSIONS Structural corticocancellous autografts from the ilium can be successfully used in repair of periprosthetic acetabular fractures after THA. CLINICAL RELEVANCE Structural corticocancellous grafting from the ilium can be considered as a treatment option for repair of periprosthetic acetabular fractures after THA.

Comparison of two methods for analyzing kinetic gait data in dogs

OBJECTIVE To compare results of single-point kinetic gait analysis (peak and impulse) with those of complete gait waveform analysis. ANIMALS 15 healthy adult mixed-breed dogs. PROCEDURES Dogs were trotted across 2 force platforms (velocity, 1.7 to 2.1 m/s; acceleration and deceleration, 0.5 m/s(2)). Five valid trials were recorded on each testing day. Testing days 1 and 2 were separated by 1 week, as were days 3 and 4. Testing days 1 and 2 were separated from days 3 and 4 by 1 year. A paired t test was performed to evaluate interday and interyear differences for vertical and craniocaudal propulsion peak forces and impulses. Vertical and craniocaudal propulsion force-time waveforms were similarly compared by use of generalized indicator function analysis (GIFA). RESULTS Vertical and craniocaudal propulsion peak forces and impulses did not differ significantly between days 1 and 2 or days 3 and 4. When data were compared between years, no significant differences were found for vertical impulse and craniocaudal propulsion peak force and impulse, but differences were detected for vertical peak force. The GIFA of the vertical and craniocaudal force-time waveforms identified significant interday and interyear differences. These results were identical for both hind limbs. CONCLUSIONS AND CLINICAL RELEVANCE Findings indicated that when comparing kinetic data overtime, additional insight may be gleaned from GIFA of the complete waveform, particularly when subtle waveform differences are present.

Effects of firocoxib, meloxicam, and tepoxalin administration on eicosanoid production in target tissues of healthy cats.

OBJECTIVE To evaluate the effects of firocoxib, meloxicam, and tepoxalin administration in healthy cats by measuring the ability of stimulated tissues to synthesize eicosanoids ex vivo. ANIMALS 8 healthy adult male cats. PROCEDURES In a blinded, randomized, crossover study design, cats were treated with firocoxib (1 mg/kg, PO, q 24 h), meloxicam (0.05 mg/kg, PO, q 24 h), tepoxalin (5.0 mg/kg, PO, q 12 h), or a placebo for 8 days. Blood samples and gastric and duodenal mucosal biopsy specimens were collected on days 0 (baseline; immediately before treatment), 3, and 8 of each treatment period. Thromboxane B2 (TXB2) concentrations were measured in serum, and prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) concentrations were measured in plasma. Prostaglandin E1 (PGE1) synthesis, PGE2 synthesis, and LTB4 concentrations were measured in mucosal biopsy specimens. A 21-day minimum washout period was observed between treatments. Repeated-measures analyses were performed. RESULTS Firocoxib and meloxicam administration resulted in a lower plasma PGE2 concentration than at baseline on days 3 and 8 of administration, whereas tepoxalin administration did not. Tepoxalin administration resulted in a lower serum TXB2 concentration and pyloric and duodenal PGE1 synthesis on both days, compared with baseline and placebo administration. Neither firocoxib nor meloxicam administration altered pyloric or duodenal PGE1 synthesis on either day, compared with placebo administration. Tepoxalin administration also resulted in lower pyloric mucosal LTB4 concentrations on both days, compared with baseline values. CONCLUSIONS AND CLINICAL RELEVANCE Firocoxib and meloxicam administration had no effect on cyclooxygenase-1 activity, whereas tepoxalin administration resulted in inhibition of cyclooxygenase-1 and 5-lipoxygenase.