Blood volume and rate of growth in Standardbred foals

Curriculum vitae paper - Sune G.B. Persson (1931-2009)

Sune Persson was born in Landskrona Sweden in 1931 and grew up on the west coast of Sweden. He graduated from the Royal Veterinary College in Stockholm in 1960 and in 1967 received his PhD entitled ‘On blood volume and working capacity in horses’. Sune pursued an academic career devoted to internal medicine and exercise physiology. He rapidly became Professor of Medicine in 1979 as the veterinary school moved from Stockholm to the Swedish University of Agricultural Sciences in Uppsala.

Growth curves from birth to weaning for Thoroughbred foals raised on pasture

AIM

To mathematically describe the growth of a population of Thoroughbred foals reared on pasture in New Zealand from birth to weaning.

METHODS

Twice-monthly liveweight data (including birthweight; BW) from 218 foals (98 colts and 120 fillies) born over a 6-year period, and reared on four different pasture types, were available for analysis. Data truncated to the time of weaning (107-217 days old) provided 3,200 data points. After testing for non-linearity of the relationship of age and liveweight (LW), five non-linear regression equations were tested for goodness of fit.

RESULTS

Colts and fillies had similar BW, weaning ages, weaning weights (WW) and average daily gain (ADG) between birth and weaning (ADG b-w). Weaning age explained 48% (p<0.001) of the variation in WW and 11% (p<0.001) of the variation in ADGb-w. After correction for weaning age, BW explained 16% (p<0.001) of the variation in WW and 6% (p<0.001) of the variation in ADG b-w. The best fit of age and LW was the polynomial equations based on Akaike's information criteria (AIC), residual variance (RV), residual standard deviation (RSD), and coefficient of determination (R2). The most accurate, biologically sound representation of growth was provided by Brody's type equation: LW = [b0- (b0-BW) x e(-b1 x age)], and an equation including BW: LW = [((b0 x BW x age) + BWb1)b2], that was developed in this study (b0 is an intercept, b1 and b2 are regression coefficients, and e is the base of natural logarithms). The advantage of the Brody's equation is that ADG at a given LW can simply be calculated as: ADG (kg/day) = (b0 x b1)-b1 x LW.

CONCLUSIONS AND CLINICAL RELEVANCE

The similarity of the present data with growth data from the Northern Hemisphere provides further recognition that foals reared on pasture can grow as well as foals reared in grain-based systems in the Northern Hemisphere. BW provides a logical set point for the explanation of growth of the foal up to weaning, rather than the use of polynomial equations, which do not fully describe the biology of growth, even though they provide an accurate mathematical description.

Nutritional Support for Neonatal Foals

In recent years, equine neonatal medicine has made significant advances. The importance of nutritional support for the sick neonatal foal has been recognized, and methods of providing that sup-port have been developed. Today, the clinician has many options when designing a nutritional plan for the neonatal foal. When the foal's gut permits, enteral diets are an inexpensive source of nutrients. Under conditions where the gut requires rest, methods for delivering nutrients by the parenteral route have also been developed. In this article, the nutrition of the normal and sick foal is described. Guidelines for designing a nutritional plan are also reviewed.

Total blood volume in the normally performing Standardbred trotter: age and sex variations

The purposes of this study were to elucidate the influences of age and sex on the mass specific blood volume parameters: total blood volume (TBV/BW, ml/kg), plasma volume (PV/ BW, ml/kg), total red cell volume (CV/BW, ml/kg) and maximal packed cell volume (PCV, l/l, i.e. after total mobilisation of the splenic red cell reservoir) and to establish reference values for these in normally performing Standardbred trotting race horses. In total 205 horses were studied. They were all, according to their owners and/or trainers, performing satisfactorily in racing or training for shortly impending racing. Blood volume determination was done with the Evans blue dye dilution technique after exercise induced emptying of the spleen. Both age and sex were found to influence variation of these parameters significantly, with the possible exception of PV/BW, whereas the primary variation appeared to be in CV/BW. It was concluded that taking age and sex dependent variations into consideration will render prediction of normal values for the blood volume parameters in the athletic Standardbred trotter more reliable and the detection of abnormal deviations more precise if five age and sex groups are used for comparisons.

Longitudinal growth analysis of horses following limited and ad libitum feeding

Eighteen colts were assigned to one of two groups: limit or ad libitum feeding. Three periods were evaluated: 1) six to 12 months, 2) 12 to 18 months and 3) 18 to 24 months of age. At 24 months of age, ad libitum fed horses weighed 13 per cent (51 kg) more and were 3.6 per cent (5.2 cm) taller than those fed limited amounts. Total, fore and hind body mass increased quadratically irrespective of dietary treatment. Fore body mass comprised 57 per cent of total body mass for both groups and this did not change with age or dietary treatment. Heart girth was directly related (R2 = 0.96) to total body mass. Average daily gains in total body mass of ad libitum fed horses were 13 and 71 per cent more rapid (P less than 0.05) than for limit fed horses in Periods 1 and 3, respectively. Ad libitum fed horses gained hind body mass 25 per cent more rapidly (P less than 0.05) than limit fed horses only in Period 1. Growth curves of wither and croup heights were quadratic in form. Ad libitum fed horses gained 12 and 13 per cent more rapidly at the wither than limit fed horses in Period 1 and overall, respectively. Ad libitum fed horses grew 33 per cent more rapidly at the croup than limit fed horses but only in Period 2. From six to 12 months of age, the wither and croup grew two-fold and four-fold more rapidly than between 12 to 18 months and between 18 to 24 months of age, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Hematology, blood typing, and immunology of the neonatal foal

Hematologic parameters change during the first 10 days of life. Erythrocytes increase in number but decrease in size and hemoglobin concentration. The PCV, hemoglobin, and platelet count also decrease. Total blood and plasma volume and, to lesser extent, erythrocyte volume decrease. Normal neonatal foals may have immature neutrophils (up to 5 per cent bands), and their early rapid rise in neutrophil numbers may be accompanied by a lymphopenia. Monocytes, eosinophils, and basophils are all absent or low initially. Infectious processes can cause rapid and variable changes in the leukogram. However, elevation of fibrinogen levels may lag behind the development of an inflammatory process, and this parameter should not be relied on for early evidence of infection. After 12 hours of life, there is generally a decrease in serum concentrations of Na, Cl, iron, creatinine, BUN, plasma protein, and possibly calcium. LDH, SAP, P, bilirubin, and glucose concentrations are all higher in foals than in mature horses. Creatinine may actually be elevated during the first 12 hours of life and then decreases. If azotemia, hypochloremia, hyponatremia, and hyperkalemia are found, ruptured bladder with uroperitoneum should be suspected. The creatinine concentration is preferable to BUN determination for diagnosis of this condition. Blood typing is useful for diagnosis of NI, determination of blood compatability between donor and transfusion recipient, and for verification of parentage for breed registries. Several techniques are available. Several tests are available for evaluation of the foal's immunoglobulin levels and confirmation of passive antibody transfer. Because foals suffering from FPT are more predisposed to infections, their immunoglobulin status should be determined as early as possible so that additional colostrum or plasma can be administered as needed. Neonatal isoerythrolysis is uncommon but is an important immunologic syndrome that often results in a fatal hemolytic crisis. If one suspects the condition may be likely, the optimal time for testing the mare is during the last 2 weeks of gestation. If the foal's dam is shown to have alloantibodies against a panel of known erythrocyte alloantigens, prevention is possible by feeding colostrum from another mare. If a foal develops NI, further colostrum ingestion from the dam must be prevented. Good nursing care, minimizing stress, and adequate frequent feedings are essential; prophylactic antibiotics should be used, and transfusion may be necessary.