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  • Author or Editor: Dr. David M. Bolt x
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in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate the effects of triamcinolone acetonide (TA), sodium hyaluronate (HA), amikacin sulfate (AS), and mepivacaine hydrochloride (MC) on articular cartilage morphology and matrix composition in lipopolysaccharide (LPS)-challenged and unchallenged equine articular cartilage explants.

Sample Population—96 articular cartilage explants from 4 femoropatellar joints of 2 adult horses.

Procedures—Articular cartilage explants were challenged with LPS (100 ng/mL) or unchallenged for 48 hours, then treated with TA, HA, AS, and MC alone or in combination for 96 hours or left untreated. Cartilage extracts were analyzed for glycosaminoglycan (GAG) content by dimethyl-methylene blue assay (ng/mg of dry wt). Histomorphometric quantification of total lacunae, empty lacunae, and lacunae with pyknotic nuclei was recorded for superficial, middle, and deep cartilage zones.

Results—LPS induced a significant increase in pyknotic nuclei and empty lacunae. Treatment with TA or HA significantly decreased empty lacunae (TA and HA), compared with groups without TA or HA, and significantly decreased empty lacunae of LPS-challenged explants, compared with untreated explants. Treatment with AS or MC significantly increased empty lacunae in unchallenged explants, and these effects were attenuated by TA. Treatment with MC significantly increased empty lacunae and pyknotic nuclei and, in combination with LPS, could not be attenuated by TA. Content of GAG did not differ between unchallenged and LPS-challenged explants or among treatments.

Conclusions and Clinical Relevance—Treatment with TA or HA supported chondrocyte morphology in culture and protected chondrocytes from toxic effects exerted by LPS, AS, and MC.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To examine factors associated with short- and long-term prognosis for horses undergoing repeated celiotomy within 14 days after the first colic surgery.

Design—Retrospective case series.

Animals—95 horses that had undergone 2 celiotomies within a 14-day period between 2005 and 2013 at 3 equine referral hospitals.

Procedures—Historical, clinical, and laboratory data were compared between horses that did not survive and horses that did survive to hospital discharge (short-term survival rate) and to > 3 and > 6 months after hospital discharge (long-term survival rates).

Results—Strangulating small intestinal lesions were the most common finding during the first celiotomy (60/95 [63.2%]), and persistent gastric reflux was the most common reason for the second celiotomy (56/95 [58.9%]). Reasons for a second celiotomy were not associated with survival rate. For horses that had long-term follow-up, 22 of 92 (23.9%) survived > 6 months after hospital discharge. Two of 13 horses with intestinal resections during both surgeries survived to > 6 months after hospital discharge. Compared with horses not undergoing intestinal resection, significantly fewer horses requiring resection during 1 or both surgeries survived to hospital discharge and to > 3 and > 6 months after hospital discharge. Incisional infections occurred in 68.4% (26/38) of horses that survived to hospital discharge, and 31.6% (12/38) developed incisional hernias or dehiscence.

Conclusions and Clinical Relevance—Results indicated that the prognosis for horses undergoing repeated celiotomy is guarded, and intestinal resection negatively affects the long-term survival rate.

Restricted access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To assess analgesia, inflammation, potency, and duration of action associated with intra-articular injection of triamcinolone acetonide (TA), mepivacaine hydrochloride, or both in metacarpophalangeal (MCP) joints of horses with experimentally induced acute synovitis.

Animals—18 horses.

Procedures—Both forelimbs of each horse were injected with lipopolysaccharide (LPS) 3 times. After the first LPS injection, 1 forelimb of each horse was treated with intra-articular injection of mepivacaine (80 mg; n = 6), TA (9 mg; 6), or mepivacaine with TA (same doses of each; 6) 12 hours after the initial LPS injection. Contralateral limbs served as control limbs. Joint pain was assessed via lameness score and measurements of vertical force peak and pain-free range of motion of the MCP joint. Periarticular edema was evaluated. Degree of synovial inflammation was determined via synovial fluid analysis for WBC count and total protein concentration. Samples of plasma and synovial fluid were analyzed for TA and mepivacaine concentrations.

Results—Each injection of LPS induced lameness and joint inflammation. Mepivacaine effectively eliminated lameness within 45 minutes after injection, regardless of whether TA was also administered, whereas TA reduced lameness, edema, and concentration of synovial fluid protein after the second LPS injection, regardless of whether mepivacaine was also injected. Treatment with TA also induced higher WBC counts and mepivacaine concentrations in synovial fluid, compared with results for mepivacaine alone.

Conclusions and Clinical Relevance—Results suggested TA is a potent analgesic and anti-inflammatory medication for acute synovitis in horses and that simultaneous administration of mepivacaine does not alter the potency or duration of action of TA.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To develop a quantitative method of interpreting tibial scintigrams of Thoroughbred racehorses with tibial stress fractures that may facilitate diagnosis of fractures and to provide prognostic information regarding future performance of affected horses.

Animals—35 Thoroughbred racehorses.

Procedures—Static bone-phase scintigrams of tibial stress fractures were quantitatively analyzed by use of ratios of the mean radionuclide counts per pixel in a region of interest (ROI) drawn around the area of increased uptake of radiopharmaceutical to mean counts per pixel in a second ROI drawn around an apparently normal area of the tibial diaphysis. In horses with unilateral fractures, ratios for the contralateral tibia were determined by use of 2 ROIs drawn at the same positions as the ROIs in the fractured tibia. Ratios were compared between fractured versus apparently normal tibias, between horses that returned to racing versus those that did not, and among horses with various grades of lameness. The association between ratios for fractured tibias and intervals between diagnosis and return to racing was also assessed.

Results—Mean ratio of ROIs in apparently normal tibias was 1.35 (95% confidence interval [CI], 1.21 to 1.50); that in tibias with stress fractures was 3.55 (95% CI, 2.50 to 4.60). These ratios were significantly different. None of the associations between ratios for fractured tibias and grades of lameness or performance outcomes were significant.

Conclusions and Clinical Relevance—Tibial stress fracture scintigrams can be quantitatively analyzed. A prospective study with a controlled rehabilitation period is necessary to evaluate the possible applications of this method.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine functional and morphologic changes in palmar digital nerves after nonfocused extracorporeal shock wave (ESW) treatment in horses.

Animals—6 horses.

Procedures—The medial and lateral palmar digital nerves of the left forelimb were treated with nonfocused ESWs. The medial palmar digital nerve of the right forelimb served as a nontreated control nerve. At 3, 7, and 35 days after treatment, respectively, 2 horses each were anesthetized and nerves were surgically exposed. Sensory nerve conduction velocities (SNCVs) of treated and control nerves were recorded, after which palmar digital neurectomies were performed. Morphologic changes in nerves were assessed via transmission electron microscopy.

Results—Significantly lower SNCV in treated medial and lateral nerves, compared with control nerves, was found 3 and 7 days after treatment. A significantly lower SNCV was detected in treated medial but not lateral nerves 35 days after treatment. Transmission electron microscopy of treated nerves revealed disruption of the myelin sheath with no evidence of damage to Schwann cell bodies or axons, 3, 7, and 35 days after treatment.

Conclusions and Clinical Relevance—Nonfocused ESW treatment of the metacarpophalangeal area resulted in lower SNCV in palmar digital nerves. This effect likely contributes to the post-treatment analgesia observed in horses and may result in altered peripheral pain perception. Horses with preexisting lesions may be at greater risk of sustaining catastrophic injuries when exercised after treatment. (Am J Vet Res 2004;65:1714–1718)

Full access
in American Journal of Veterinary Research