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in Journal of the American Veterinary Medical Association

Summary

The effects of intra-articular administration of methylprednisolone acetate (mpa) on the healing of full-thickness osteochondral defects and on normal cartilage were evaluated in 8 horses. In group-1 horses (n = 4), a 1-cm-diameter, full-thickness defect was created bilaterally in the articular cartilage on the dorsal distal surface of the radial carpal bone. Cartilage defects were not created in group-2 horses (n = 4). One middle carpal joint was randomly selected in each horse (groups 1 and 2), and treated with an intra-articular injection of 100 mg of mpa, once a week for 4 treatments. Injections began 1 week after surgery in group-1 horses. The contralateral middle carpal joint received intra-articular injections of an equivalent volume of 0.9% sodium chloride solution (scs), and served as a control. Horses were evaluated for 16 weeks, then were euthanatized, and the middle carpal joints were examined and photographed. Synovial and articular cartilage specimens were obtained for histologic and histochemical evaluation.

Gross morphometric evaluation of the healing defects in group-1 horses revealed that 48.6% of the defect in control joints and 0% of the defect in mpa-treated joints was resurfaced with a smooth, white tissue, histologically confirmed as fibrocartilage. This replacement tissue was a firmly attached fibrocartilage in control joints and a thin fibrous tissue in mpa-treated joints. The articular cartilage in joints treated with mpa had morphologic changes, including chondrocyte cluster formation, loss of palisading architecture, and cellular necrosis in both groups of horses. Histochemical (safranin-0) staining intensity was reduced significantly (P < 0.05) in all layers of articular cartilage in mpa-treated joints in groups 1 and 2. In the replacement tissue, intense safranin-0 staining was found only in the chondrocyte clusters deep in the tissue of control joints, confirming fibrocartilage repair. Intra-articular administration of mpa in this dosing regimen thus induced degenerative changes in normal articular cartilage and resulted in histomorphologic changes in the repair of full-thickness articular osteochondral defects in horses.

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in American Journal of Veterinary Research

Abstract

Objective—To determine the effects of rapid small-volume fluid administration on arterial blood pressure measurements and associated hemodynamic variables in isoflurane-anesthetized euvolemic dogs with or without experimentally induced hypotension.

Design—Prospective, randomized, controlled study.

Animals—13 healthy dogs.

Procedures—Isoflurane-anesthetized dogs were randomly assigned to conditions of nonhypotension or hypotension (mean arterial blood pressure, 45 to 50 mm Hg) and treatment with lactated Ringer's solution (LRS) or hetastarch (3 or 10 mL/kg [1.4 or 4.5 mL/lb] dose in a 5-minute period or 3 mL/kg dose in a 1-minute period [4 or 5 dogs/treatment; ≥ 10-day interval between treatments]). Hemodynamic variables were recorded before and for up to 45 minutes after fluid administration.

Results—IV administration of 10 mL/kg doses of LRS or hetastarch in a 5-minute period increased right atrial and pulmonary arterial pressures and cardiac output (CO) when dogs were nonhypotensive or hypotensive, compared with findings before fluid administration; durations of these effects were greater after hetastarch administration. Intravenous administration of 3 mL of hetastarch/kg in a 5-minute period resulted in an increase in CO when dogs were nonhypotensive. Intravenous administration of 3 mL/kg doses of LRS or hetastarch in a 1-minute period increased right atrial pressure and CO when dogs were nonhypotensive or hypotensive.

Conclusions and Clinical Relevance—Administration of LRS or hetastarch (3 or 10 mL/kg dose in a 5-minute period or 3 mL/kg dose in a 1-minute period) improved CO in isoflurane-anesthetized euvolemic dogs with or without hypotension. Overall, arterial blood pressure measurements were a poor predictor of the hemodynamic response to fluid administration.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To provide an updated evaluation of the efficacy and safety of sometribove zinc suspension (rbST-Zn), a form of recombinant bovine somatotropin, in lactating dairy cows.

Design—Meta-analysis.

Sample—26 studies published in peer-reviewed journals or reviewed by a regulatory agency.

Procedures—To be included, a study had to involve the use of the rbST-Zn formulation available to US producers in accordance with the label instructions for treatment initiation (57 to 70 days postpartum), dose (500 mg, q 14 d), and route (SC).

Results—For cows treated with rbST-Zn, mean milk, 3.5% fat-corrected milk, fat, and protein yields were increased by 4.00, 4.04, 0.144, and 0.137 kg/d (8.8, 8.89, 0.32, and 0.30 lb/d), respectively; however, the concentration of milk components did not change. Pregnancy proportion for the first 2 breeding cycles was increased by 5.4%, and pregnancy proportion for the duration of the trial was reduced by 5.5% for rbST-Zn–treated cows, compared with proportions for untreated cows. Mean body condition score (1 to 5 scale) was reduced by 0.06 points during the period of rbST-Zn use for treated cows. Administration of rbST-Zn had no effect on milk somatic cell count, the number of days to pregnancy, or inseminations per pregnancy; rates of fetal loss, twins, cystic ovaries, clinical lameness, lameness lesions, or traumatic lesions of the integumentary system; and odds of clinical mastitis or culling.

Conclusions and Clinical Relevance—Results indicated that rbST-Zn administration to dairy cows effectively increases milk production with no adverse effects on cow health and well-being.

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in Journal of the American Veterinary Medical Association
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in Journal of the American Veterinary Medical Association
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in Journal of the American Veterinary Medical Association