Dietary molybdenum as a putative copper antagonist in the horse

Four horses were stabled and fed a diet of hay ad libitum, and 2 kg oats per animal per day, for a month. The basic diet was then supplemented with molybdenum, at a rate of 20 mg/kg dry matter for 4.5 months. For one month of this period the diet was supplemented also with sulphur at a rate of 1.2 g/kg dry matter. Analyses of jugular blood samples, obtained at intervals varying between two and 20 days, showed no evidence of a decline in total plasma copper or of an increased proportion of trichloroacetic acid (TCA) insoluble copper in plasma over this period. In separate studies, two other horses were given 99molybdenum (molybdate, 20 to 28 mg Mo, 4 mCi per animal) per os, initially while being fed the basic diet and later while maintained on the molybdenum supplemented diet. 99Molybdenum appeared rapidly in plasma, but the radioactivity was then quickly cleared (half-life 7 to 10 h). The 99molybdenum present was identified as (99Mo)-molybdate. There was no evidence of the persistent, protein-bound (99Mo)thiomolybdates which appear in ruminants. These studies indicate that increased dietary molybdenum is unlikely to interfere with copper metabolism in horses.     

Use of a continuous, local infusion of bupivacaine for postoperative analgesia in dogs undergoing total ear canal ablation

OBJECTIVE: To determine whether addition of a continuous, local infusion of bupivacaine would improve postoperative analgesia in dogs undergoing total ear canal ablation. DESIGN: Randomized controlled trial. ANIMALS: 16 dogs undergoing total ear canal ablation (12 unilaterally and 4 bilaterally with > 1 month between procedures). PROCEDURE: Dogs were randomly allocated to receive morphine (0.25 mg/kg [0.11 mg/lb]) at the end of the procedure (10 procedures) or morphine and a continuous, local infusion of bupivacaine (0.13 to 0.21 mg/kg/h [0.06 to 0.1 mg/lb/h]; 10 procedures). Dogs were observed for 48 hours after surgery. Additional doses of morphine were administered up to every 4 hours in dogs with signs of severe pain. RESULTS: Temperament, sedation, analgesia, and cumulative pain scores were not significantly different between groups any time after surgery. Recovery score was significantly higher for dogs that received bupivacaine than for control dogs 2 hours after extubation but not at any other time. Serum cortisol concentration was not significantly different between groups at any time but, in both groups, was significantly increased at the time of extubation, compared with all other observation times. Total number of additional doses of morphine administered was not significantly different between groups. Bupivacaine was not detected in the plasma of any of the dogs that received the local bupivacaine infusion. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that addition of a continuous, local infusion of bupivacaine did not significantly increase the degree of postoperative analgesia in dogs that underwent total ear canal ablation and were given morphine at the end of surgery.     

Effects of CD28 blockade on subsets of naïve T cells in cats

OBJECTIVE: To determine whether human CTLA4-Ig ([hu]CTLA4-Ig) inhibits costimulation-dependent lymphocyte proliferation in vitro, compare the effects of (hu)CTLA4-Ig with cyclosporine and steroids on CD4+ and CD8+ T-cell lymphocyte proliferation, and determine whether memory T-cell function remains intact in the presence of (hu)CTLA4-Ig. ANIMALS: 29 cats. PROCEDURE: Peripheral blood mononuclear cells (PBMCs) were stimulated with concanavalin A (costimulation-dependent mitogen) or phorbol 12-myristate 13-acetate and ionomycin (costimulation independent mitogens) alone or in the presence of (hu)CTLA4-Ig, cyclosporine, or dexamethasone; effects of these treatments on lymphocyte proliferation were assessed by incorporation of thymidine labeled with tritium or flow cytometry. Antigen-specific proliferation was determined by stimulating PBMCs from 2 healthy cats seropositive for Toxoplasma gondii with soluble Toxoplasma antigen alone or in the presence of (hu)CTLA4-Ig or cyclosporine. RESULTS: (hu)CTLA4-Ig inhibited costimulation-dependent lymphocyte proliferation in vitro but had no effect on costimulation-independent lymphocyte proliferation. Compared with mitogen alone, (hu)CTLA4-Ig caused a significant decrease in responder frequency and proliferative capacity of CD4+ T cells; however, the effect on CD8+ T cells was not significant. Cyclosporine alone or with dexamethasone had a significantly greater suppressive effect on responder frequency and proliferative capacity of CD4+ and CD8+ T cells, compared with (hu)CTLA4-Ig. Compared with cyclosporine, (hu)CTLA4-Ig appeared to have a sparing effect on antigen-specific proliferation of memory CD4+ and CD8+ T cells. CONCLUSIONS AND CLINICAL RELEVANCE: (hu)CTLA4-Ig selectively inhibited costimulation-dependent proliferation of lymphocytes in vitro and had a sparing effect on antigen-specific proliferation of memory cells. The specificity of its mechanism of action suggests that (hu)CTLA4-Ig may prevent allograft rejection but leave memory responses to previously encountered antigens intact.     

Effects of a whole-body spandex garment on rectal temperature and oxygen consumption in healthy dogs

OBJECTIVE: To determine whether a full-body spandex garment would alter rectal temperatures of healthy dogs at rest in cool and warm environments. DESIGN: Prospective study. ANIMALS: 10 healthy dogs. PROCEDURES: Each dog was evaluated at a low (20 degrees to 25 degrees C [68 degrees to 77 degrees F]) or high (30 degrees to 35 degrees C [86 degrees to 95 degrees F]) ambient temperature while wearing or not wearing a commercially available whole-body spandex garment designed for dogs. Oxygen consumption was measured by placing dogs in a flow-through indirect calorimeter for 90 to 120 minutes. Rectal temperature was measured before dogs were placed in the calorimeter and after they were removed. RESULTS: Rectal temperature increased significantly more at the higher ambient temperature than at the lower temperature and when dogs were not wearing the garment than when they were wearing it. The specific rate of oxygen consumption was significantly higher at the lower ambient temperature than at the higher temperature. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that wearing a snug spandex body garment does not increase the possibility that dogs will overheat while in moderate ambient temperatures. Instead, wearing such a garment may enable dogs to better maintain body temperature during moderate heat loading. These results suggest that such garments might be used for purposes such as wound or suture protection without causing dogs to overheat.     

Biomechanical comparison of cortical radial graft versus ulnar transposition graft limb-sparing techniques for the distal radial site in dogs

OBJECTIVE: To compare the biomechanical properties of radial graft (RG) versus ulnar transposition graft (UTG) limb-sparing techniques in the dog. STUDY DESIGN: Cadaveric study. ANIMALS: Six pairs of normal canine thoracic limbs. METHODS: In each pair of limbs, 1 limb was subjected to the RG technique and the other to the UTG technique. Limbs were tested in axial loading until failure. Modes of failure and biomechanical properties were compared between the 2 groups. Percent coverage of the metacarpal bone by the plate was retrospectively compared between the limbs that failed by fracture of the metacarpal bones and those that did not. RESULTS: RG limbs had significantly greater stiffness, yield load, maximum load, maximum energy, and post-yield energy. All UTG limbs failed by cranial bending of the plate. Half of the RG limbs failed by caudal bending of the plate and half by fracture of the third metacarpal bone at the distal end of the plate. Limbs with <80% plate coverage of the metacarpal bone were significantly more likely to fail by metacarpal fracture. CONCLUSIONS: The RG technique was biomechanically superior to the UTG technique under the conditions studied. At least 80% plate coverage of the metacarpal bone should be achieved. CLINICAL RELEVANCE: Exercise restriction and coaptation bandages should be considered for patients undergoing the UTG technique to minimize potential biomechanical complications.