Methods and normal values for echocardiography in adult dairy cattle

ObjectiveThe objective of the study was to report normal ultrasonographic appearance and intra-cardiac dimensions in two dairy breeds and to calculate cardiac output (CO) using echocardiography.BackgroundIntra-cardiac dimensions, time indices and CO estimation have not previously been reported in adult cattle.Animals, materials and methodsEchocardiograms were obtained from healthy adult dairy cows (10 Jersey (J) and 12 Holstein Friesians (HF)) in the body weight range of 400 to 700 kg. Standard echocardiographic images were obtained from the left and right hemithoraces. Velocity time integrals were obtained in order to calculate CO using pulsed wave Doppler of aortic flow in the J cows. Measurements obtained included pulmonary artery and aortic diameters, left and right ventricular diameters (and calculated fractional shortening and left ventricular ejection fraction), left atrial size and time indices assessing valve function.ResultsHF cows had significantly (p < 0.05) larger pulmonary artery and aortic diameters, larger left atrial diameters and left ventricular internal diameters during diastole, but these were not different when corrected for body weight. Left and right ventricular dimensions, adjusted for body weight, were significantly larger (p = 0.02 and p = 0.035 respectively) in J cows when compared to HF cows. No differences were noted in the time indices between the two groups. No significant differences were noted in intra-operator variability and the only significant difference in inter-operator variability was in measurement of the pulmonary artery (p = 0.03; ICC = 0.63).ConclusionsIt is possible to obtain repeatable, reliable echocardiograms in order that meaningful intra-cardiac dimensions can be obtained in adult dairy cattle.     

Comparison of two insulin protocols for diabetic dogs undergoing cataract surgery

Objective To evaluate the effectiveness of two insulin doses to maintain an acceptable range of blood glucose concentrations (70–200 mg dL^?1) in the peri‐operative period in diabetic dogs. Animals Twenty‐four diabetic dogs with a median weight of 20.6 kg and a median age of 8 years old. Methods The dogs were randomly assigned to receive either 25 or 100% of their normal insulin dose subcutaneously on the morning of surgery. The anesthetic and feeding protocols were standardized. On the day before surgery, venous blood was collected for measurement of β‐hydroxybutyrate, cholesterol, glucose, glycosylated hemoglobin, hematocrit, total plasma protein and urea nitrogen. On the day of surgery, blood glucose concentrations were measured prior to anesthesia, prior to the start of surgery, 1 and 2 hours after beginning of surgery, 1 hour after extubation, at 16 : 00 hours and at 20 : 00 hours. β‐hydroxybutyrate concentrations were measured at 20 : 00 hours that day. At 08 : 00 hours the following day, β‐hydroxybutyrate and glucose concentrations were measured. The significance of differences between groups was tested with Wilcoxon's two‐tailed rank‐sum test, Chi‐square test and Fisher's exact test. Results There were no differences in insulin treatments, clinical signs, concurrent diseases and most clinicopathological parameters between the two groups of dogs at entry to the study. The 25% dose group had blood glucose values of 296 (102–601) mg dL^?1 at 16 : 00 hours and 429 (97–595) mg dL^?1 at 20 : 00 hours on the day of surgery. The 100% insulin dose group had lower corresponding values of 130 (55–375) mg dL^?1 (p = 0.04) and 185 (51–440) mg dL^?1 (p = 0.004). No other differences (p < 0.05) were detected between the two groups. Conclusions The administration of a full dose of insulin is only marginally advantageous for reducing glucose to normal (70–120 mg dL^?1) after anesthesia but neither dose consistently induced glycemic values in an acceptable range (70–200 mg dL^?1) or normoketonemia. Clinical relevance Blood glucose should be measured immediately before anesthesia and periodically throughout the peri‐operative period in all diabetic dogs because presurgical subcutaneous administration of 25 or 100% of the normal insulin dose resulted in unpredictable blood glucose concentrations.     

Body fluids and exercise: Physiological responses (part I)

Athletic performance is initially enabled but then becomes limited by changes in body fluids. This subject is reviewed in three parts: physiological responses, replacement strategies, and dietary influences. The first part provides a physiological basis for understanding body fluids and typical changes during exercise, with emphasis on water and electrolytes. It describes the volume and distribution of body water, and the water shifts and changes in concentrations of electrolytes that occur during strenuous exercise, whether brief or prolonged. These changes may relate to muscle activity or reflect losses via sweat or expiration. Changes in electrolyte concentrations influence acid-base status, with decreasing concentrations of strong ions in the horse (but not most species) tending to exacerbate the acidogenic effect of exercise. Electrolyte changes during exercise also tend to exert many effects on neuromuscular excitability, with the extracellular potassium concentration likely to play a dominant role. Relative losses of water and electrolytes lead to hypo-, iso- or hyper-osmotic hypohydration. Loss of equine hypertonic sweat is conducive to hypotonic plasma, and this hypotonicity inhibits voluntary water intake. Reduction in plasma volume initially increases oxygen carriage per unit volume so favors oxygen transport but, if more extreme, risks hypotension or acute heart failure. Reduction of cellular water initially sustains plasma volume but eventually compromises performance. Hypohydration reduces the sweating rate and compromises heat elimination. Increasing muscle temperature at first improves performance (“warming up”) then induces fatigue. The regulation of body water volume is controlled to a large extent by conservation of sodium. Total water turnover is related to energy expenditure, and both variables are dependent largely on the same internal and external factors. The horse's homeostatic capacity may be influenced by diet in general or be supported by supplementation with water and electrolytes before, during or after an event. Potentially beneficial replacement strategies and dietary designs will be discussed in parts two and three of this review.     

Endotoxin release after antimicrobial treatment in sick foals is mediated by antimicrobial class

The objective of this study was to determine whether treatment with antimicrobials leads to increased serum endotoxin concentrations in sick foals and to further determine whether an effect of class of antimicrobial on endotoxin release occurs in sick foals in vivo. This was a prospective, observational study at a university equine hospital. Twenty-four foals aged 12 hours to 12 days admitted to the hospital in 2004 and 2005 were used. Blood was collected from all foals at time 0 (admission) and at 30 minutes, 8 hours, 12 hours, and 24 hours after treatment with an antimicrobial. The choice of antimicrobial was determined by the clinician caring for the foal, and any other treatment, as deemed necessary for appropriate care of the foal, was employed. For each serum sample, the endotoxin concentration was determined using the limulus amebocyte lysate assay. Those foals that received a beta-lactam alone, more specifically the cephalosporin ceftiofur, showed a significant increase in endotoxin concentration 12 hours after antibiotic administration (P = .005). An increase in serum endotoxin concentration was not seen in the first 24 hours after antimicrobial administration when foals were treated with a combination of beta-lactam and aminoglycoside antimicrobials. In conclusion, a significant increase in endotoxin concentration as a consequence of ceftiofur administration occurs in sick foals. Administration of a combination of a beta-lactam antimicrobial and an aminoglycoside did not result in a significant increase in endotoxin release. Consideration of these findings should be made when choosing antimicrobial therapy for the sick foal.     

Body fluids and exercise: Replacement strategies

Athletic performance is initially enabled but then becomes limited by changes in body fluids. This review deals with potentially beneficial interventions replacement strategies. It is the second of a trilogy on exercise with a focus on body fluids. The first part (published previously in this Journal) concerned physiological changes in body fluids likely to affect performance. These changes are certain to tax the homeostatic capacity of a competitive horse, which may be supported by supplementation with water and electrolytes before, during or after an event. The simplest replacement strategy is to completely offset depletion, so as to maintain or restore the resting status. A preferred replacement strategy emphasizes more frequent and smaller doses during an event, so as to avoid over-riding the initial beneficial changes in body fluids. Because the turning points from enabling to limiting are not well established, effective electrolyte replacement currently depends as much on the rider's development of a specific dosage regimen (amounts and times) for an individual horse as on any scientist's rational design of a flexible formula for all horses.Marketedformulas are based on sweat loss and changes in plasma. Most contain Na, K and Cl; some also have Ca, Mg, P, glucose and nutraceuticals. Attention to hyperkalemia at speeds over 4 m/s suggests the need for two formulas—one without potassium for use during an event, the other with potassium for use before and after. Illustrative studies are examined for the validity of their physiological interpretations and their practicalimplications. They indicate various advantages from the administration of hypertonic mixtures of electrolytes in pastes or slurries a few hours before as well as during and after an event, provided that the horse has ample opportunity to drink. Nevertheless, the physiology of absorption suggests that hypertonic mixtures should be regarded as unsuitable for a clinically hypohydrated horse until shown otherwise. The third part of this series will discuss the influence of nutrition and feeding management on body fluids and performance.     

Postoperative Myositis in a Neonatal Foal: A Case Report

A foal with azotemia, acidemia, and electrolyte abnormalities was diagnosed with uroperitoneum. The foal was anesthetized with isoflurane, and throughout the 4 hours of anesthesia and abdominal surgery, its mean arterial pressure ranged between 45 and 65 mm Hg. The foal developed a myopathy postoperatively and died 24 hours after surgery.     

Surgical Correction of Angular Limb Deformity of the Forelimbs of a 7-month-old Calf

Severe angular limb deformity of the forelimbs of a 7-month-old calf was treated by temporary physeal bridging of the distal radial physes using screws and wires. Marked straightening of the deformed forelegs and improvement in ambulation were noted when the calf was evaluated at three and nine months after surgery.