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Objective—To determine concentrations of tritiated polysulfated glycosaminoglycans (3H-PSGAG) in serum, urine, and the superficial digital flexor tendon (SDFT) of rabbits after IM administration and molecular weight of 3H-PSGAG recovered from the SDFT.

Animals—Twenty-five 12-week-old New Zealand White rabbits.

Procedure—Rabbits were given a single dose of 3H-PSGAG (1.1 mg/kg [70 mCi of specific activity/kg] of body weight) IM. At each of 5 sample times (2, 24, 48, 96, and 192 hours), 5 rabbits were randomly selected and sedated, and blood and urine samples were collected. Rabbits were then euthanatized, and the SDFT were immediately harvested from the hind limbs. Scintillation spectrometry was used to detect concentration of 3H-PSGAG in fluid and tissue samples. Gel-filtration chromatography was used to determine molecular weight of recovered 3H-PSGAG.

Results—Mean concentrations of 3H-PSGAG in SDFT, serum, and urine were greatest 2 hours after administration. Tritiated PSGAG could be detected in all samples collected 192 hours after administration. Gel-filtration chromatography confirmed that 3HPSGAG detected in SDFT samples was high molecular weight PSGAG.

Conclusions and Clinical Relevance—Results indicate that PSGAG is distributed to the SDFT, serum, and urine after IM administration in rabbits. Further study is needed to determine whether the same is true in horses and to determine what effect, if any, PSGAG has on inflammation of the SDFT. (Am J Vet Res 2000;61:20–23)

Full access
in American Journal of Veterinary Research


Objective—To determine the feasibility of the use of Fourier-transform infrared (FTIR) spectroscopy within the midinfrared range to differentiate synovial fluid samples of joints with osteochondrosis from those of control samples.

Animals—33 horses with osteochondrosis of the tarsocrural joint and 31 horses free of tarsocrural joint disease.

Procedures—FTIR spectroscopy of synovial fluid was used. Sixty-four synovial fluid samples from the tarsocrural joint were collected. Of these, 33 samples were from horses with radiographic evidence of osteochondrosis of the tarsocrural joint and 31 from control joints. Disease-associated features within infrared spectra of synovial fluid were statistically selected for spectral classification, and the variables identified were used in a classification model. Linear discriminant analysis and leave-one-out cross-validation were used to develop a classifier to identify joints with osteochondrosis.

Results—12 significant subregions were identified that met the selection criteria. The stepwise discriminant procedure resulted in the final selection of 6 optimal regions that most contributed to the discriminatory power of the classification algorithm. Infrared spectra derived from synovial fluid of joints with osteochondrosis were differentiated from the control samples with accuracy of 77% (81% specificity and 73% sensitivity).

Conclusions and Clinical Relevance—The disease-associated characteristics of infrared spectra of synovial fluid from joints with osteochondrosis may be exploited via appropriate feature selection and classification algorithms to differentiate joints with osteochondrosis from those of control joints. Further study with larger sample size including age-, breed-, and sex-matched control horses would further validate the clinical value of infrared spectroscopy for the diagnosis of osteochondrosis in horses.

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in American Journal of Veterinary Research


Objective—To compare the effects of xylazine bolus versus medetomidine constant rate infusion (MCRI) on cardiopulmonary function and depth of anesthesia in dorsally recumbent, spontaneously breathing, isoflurane-anesthetized horses.

Design—Prospective, randomized crossover study.

Animals—10 healthy adult Standardbreds.

Procedures—Horses were premedicated with xylazine or medetomidine IV. Anesthesia was induced with diazepam and ketamine and maintained with isoflurane for 150 minutes. For the xylazine treatment, end-tidal isoflurane concentration was maintained at 1.7%, and xylazine (0.2 mg/kg [0.09 mg/lb], IV) was administered as a bolus at the end of anesthesia. For the MCRI treatment, end-tidal isoflurane concentration was maintained at 1.4%, and medetomidine (0.005 mg/kg/h [0.0023 mg/lb/h], IV) was infused throughout anesthesia. Physiologic data (ie, heart rate, respiratory rate, rectal temperature, bispectral index, and electromyographic values) were compared between treatments with xylazine bolus versus MCRI.

Results—Heart rate was lower, but mean arterial blood pressure was higher from 20 to 40 minutes with MCRI treatment, compared with conventional treatment with xylazine. Respiratory rate and rectal temperature were greater with MCRI treatment. Bispectral index was lower with MCRI treatment from 80 to 150 minutes, and electromyographic values were lower with MCRI treatment from 30 to 150 minutes.

Conclusions and Clinical Relevance—In isoflurane-anesthetized horses, premedication with medetomidine followed by administration of medetomidine as a constant rate infusion resulted in decreased heart rate, higher arterial blood pressure from 20 through 40 minutes after induction of anesthesia, and better preserved body temperature, compared with conventional treatment with xylazine. Greater depth of anesthesia and muscle relaxation were seen with MCRI treatment, despite the lower isoflurane concentration.

Full access
in Journal of the American Veterinary Medical Association


Objective—To evaluate use of infrared spectroscopy for diagnosis of traumatic arthritis in horses.

Animals—48 horses with traumatic arthritis and 5 clinically and radiographically normal horses.

Procedures—Synovial fluid samples were collected from 77 joints in 48 horses with traumatic arthritis. Paired samples (affected and control joints) from 29 horses and independent samples from an affected (n = 12) or control (7) joint from 19 horses were collected for model calibration. A second set of 20 normal validation samples was collected from 5 clinically and radiographically normal horses. Fourier transform infrared spectra of synovial fluids were acquired and manipulated, and data from affected joints were compared with controls to identify spectroscopic features that differed significantly between groups. A classification model that used linear discriminant analysis was developed. Performance of the model was determined by use of the 2 validation datasets.

Results—A classification model based on 3 infrared regions classified spectra from the calibration dataset with overall accuracy of 97% (sensitivity, 93%; specificity, 100%). The model, with cost-adjusted prior probabilities of 0.60:0.40, yielded overall accuracy of 89% (sensitivity, 83%; specificity, 100%) for the first validation sample dataset and 100% correct classification of the second set of independent normal control joints.

Conclusions and Clinical Relevance—The infrared spectroscopic patterns of fluid from joints with traumatic arthritis differed significantly from the corresponding patterns for controls. These alterations in absorption patterns may be used via an appropriate classification algorithm to differentiate the spectra of affected joints from those of controls.

Full access
in American Journal of Veterinary Research