Cardiovascular,Colloid Osmotic Pressure,and Hemostatic Effects of 2 Formulations of Hydroxyethyl Starch in Healthy Horses

Background

Lower molecular weight and molar substitution formulations of hydroxyethyl starch (HES) solutions might maximize cardiovascular function and colloid osmotic pressure (COP) and minimize adverse effects on coagulation.

Hypothesis/Objectives

To compare effects of 1 low and 1 high molecular weight and molar substitution HES solution on cardiovascular variables, COP, and hemostasis in normal horses.

Animals

Eight healthy adult horses.

Methods

Randomized, crossover designed study: 10 mL/kg bolus of 6% HES (600/0.75) (hetastarch) (HS), 6% HES (130/0.4) tetrastarch (TS), and 0.9% NaCl (NS). Variables recorded included central venous pressure (CVP), noninvasive arterial blood pressure, packed cell volume (PCV), COP, and automated platelet analysis (CT).

Results

Central venous pressure was increased for 8 hours after all treatment (baseline = 8.4 ± 3.8; 8 hours = 10.3 ± 3.5 cm H₂O; P < .001). HS and TS produced an increase in systolic arterial pressure (HS = 109.1 ± 11.9; TS = 109.5 ± 10.9 mmHg) and mean arterial pressure (HS = 80.4 ± 13.0; TS = 82.3 ± 10.1 mmHg) compared to NS (SAP = 103.2 ± 13.2 [P = .023]; MAP = 74.2 ± 11.4 mmHg [P = .048]). PCV decreased transiently with HS (baseline = 37.1 ± 4.4%; 1.5 hours = 31.6 ± 3.9%) and TS (baseline = 38.4 ± 3.9%; 1.5 hours = 32.2 ± 3.3%), but not NS (P = .007). COP was greater with HS (1 hour; 24.0 ± 2.1 mmHg) and TS (8 hours; 25.9 ± 2.1 mmHg) than NS (1 hour = 20.8 ± 2.6; 8 hours = 22.9 ± 3.1 mmHg; P < .001). CT was greater at 8 (HS = 178.6 ± 36.9; TS = 121.9 ± 33.3; NS = 108.3 ± 23.6 seconds) and 24 hours (HS = 174.2 ± 41.7; TS = 100.8 ± 26.0; NS = 118.7 ± 38.7 seconds; P < .001) in horses receiving HS than TS or NS.

Conclusion and Clinical Importance

Both TS and HS resulted in more effective volume expansion and arterial pressure support than NS. TS produced a more sustained effect on COP with shorter duration of adverse effects on platelet function than HS.     

Use of multisite quantitative ultrasonography for noninvasive assessment of bone in horses

OBJECTIVE: To evaluate the usefulness of multisite quantitative ultrasonography for noninvasive assessment of bone in horses. SAMPLE POPULATION: 12 healthy horses and both forelimbs from 8 clinically normal horses. PROCEDURE: For in vivo measurements, various regions of interest (ROI) were examined on the third metacarpal bone, radius, and tibia. Precision error for speed of sound (SOS) measurements was obtained by measuring each ROI of 4 horses 10 times with probe repositioning. Additionally, 3 operators measured each aspect of the third metacarpal bone of 6 horses 5 times each. For ex vivo measurements, third metacarpal bones were examined at 9 ROI, and SOS measurements were performed before and after soft tissue removal. One ROI of a single forelimb was subjected to 96 ex vivo measurements with 3 different contact media. RESULTS: The lateral aspect of the third metacarpal bone had significantly higher SOS values than the dorsal and medial aspect of the third metacarpal bone. No difference was obtained between SOS values of the lateral and medial aspect of the radius. The tibia had significantly higher SOS values than the lateral aspect of the radius and the dorsal and medial aspect of the third metacarpal bone. Intraoperator coefficients of variation ranged from 0.62 to 3.15%, and interoperator coefficients of variation ranged from 0.78 to 2.70%. Values of SOS were highest when silicone oil was used as the contact medium. CONCLUSIONS AND CLINICAL RELEVANCE: Speed of sound measurements obtained by quantitative ultrasonography in axial transmission mode can be used to precisely measure superficial cortical bone properties of third metacarpal bone, radius, and tibia in horses.     

Repair of transverse process fractures of multiple lumbar vertebrae in an adult dairy cow

Objective: To report lumbar vertebrae transverse process fracture repair using a narrow 3.5 mm limited contact dynamic compression plate (LC‐DCP) in an adult dairy cow. Study Design: Case report. Animals: A 3‐year‐old Holstein cow. Methods: Under general anesthesia, fractured left transverse processes of lumbar vertebrae 2–4 were repaired using internal fixation. A narrow 3.5 mm LC‐DCP was contoured and secured to the spinous process and the transverse process of each fractured vertebra. Results: Fractured transverse processes of the lumbar vertebrae were successfully repaired and the cow discharged 10 days after surgery. At 10 months after surgery, the cow was declared reserved champion at a regional show. Conclusion: A paramedian approach and muscle splitting can be used to repair multiple lumbar transverse process fractures using internal fixation with an excellent cosmetic outcome.     

Accreditation for freedom from ovine brucellosis

The results of operating a voluntary ovine brucellosis accreditation programme in 14 stud and 9 commercial flocks in the Manawatu district is reported. From a total of 1992 CF test results there were 47 positive and 14 suspicious reactions; a total of 61 reactions (3.06%). Fifty six of these occurred in rams vaccinated during the previous 12 months, and only one further ram with epididymitis had a suspicious, and then a positive, CF test and is assumed to have had brucellosis (0.05%). One of the remaining three suspicious reactions was confirmed as a false suspicious, and the other two remain unclassified as either true or false. It was concluded the CF test is both highly sensitive and specific, and that the official acceptance of accreditation schemes is an urgent priority for the sheep industry.     

Cross-species reactivity of seven monoclonal antibodies with equine lymphocytes by flow cytometry

The recognition of equine lymphocyte antigens by monoclonal antibodies (mAbs) directed against human CD11a, CD18, CD21, CD23, CD29 and DR, as well as mouse CD23 was studied by flow cytometry. Unlike anti-CD11a, -CD21, -CD23 and DR mAbs, anti-CD18 and CD29 mAbs labelled the same percentage of horse peripheral blood lymphocytes (PBL) as human PBL. Double-staining with anti-horse immunoglobulin antibodies showed that anti-CD21 and -CD23 mAbs are mainly bound to peripheral blood B lymphocytes. The seven mAbs were also tested on the lymph node and thymus cells. The molecular targets of anti-CD11a, CD18 and CD29 mAbs were confirmed by immunoprecipitation of the membrane proteins. Our results suggest that anti-CD18, -CD29 and -DR mAbs recognise similarly expressed molecular homologues on equine cells, but that anti-CD11a, -CD21 and -CD23 mAbs recognise either different molecules or homologues that are expressed at different levels on horse cells.     

Risk assessment of the introduction of Rift Valley fever from the Horn of Africa to Yemen via legal trade of small ruminants

Rift Valley fever (RVF) is a mosquito-borne viral zoonosis of increasing global importance. Occurring since 1930 across Africa, it was detected for the first time in Saudi Arabia and Yemen in September 2000, leading to human deaths and major losses in livestock populations. Assuming the virus has not survived in Yemen or has been circulating at a low level, authors qualitatively assessed the likelihood of “re-introduction” of RVF into Yemen through the legal importation of small ruminants from the Horn of Africa. The overall probability of introduction was assessed very low to medium, increasing during festival periods and higher when considering a direct transmission exposure as compared to a vectorial transmission exposure. The uncertainty was considered to be medium underlining important gaps in information that need to be fulfilled in the region. Options to reduce the risk are proposed and discussed, including possible improvements of the current Yemeni quarantine system.