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1.
ObjectivesThe aim of this study was to obtain echocardiographic measurements and establish reference ranges for 14 parameters in Standardbred racehorses in training.BackgroundSeveral studies have been published about cardiac measurements in Thoroughbreds, Standardbreds, National Hunt horses, Warmbloods and ponies; however, not all parameters have been published for the Standardbred trotter in training.Animals, materials and methodsThirty normal Standardbred racehorses in training were assessed by two-dimensional echocardiography (2-D) and M-mode echocardiography using standardized imaging planes. Mean values, standard deviations, 95% confidence interval for the means and 95% confidence interval for the cardiac parameters measured in the population were calculated. Furthermore, a general linear model was constructed using sex, age and body weight (bwt) of the horses as independent variables and the echocardiographic measurements as dependent variables. Multivariate linear regression analysis was performed with the level of significance at p < 0.05 for all the null hypotheses.ResultsReference ranges were established for 14 echocardiographic parameters in Standardbred racehorses. Weak linear relationships between echocardiographic measurements and body weight were observed for LVIDd, LVIDs, LVFWs, and AOD. Linear regressions on these parameters were used to calculate the 95% confidence intervals for the predicted values.ConclusionsThe data collected in this study provide reference values for the evaluation of Standardbred racehorses in training. Body weight has a negligible affect on most echocardiographic parameters in this homogeneous population, but did mildly influence the results of left ventricular and aortic measurements.  相似文献   

2.
Kerstin  Hansson  DVM  Jens  Häggström  DVM  PhD  Clarence  Kvart  DVM  PhD  Peter  Lord  BVSc  FRCVS 《Veterinary radiology & ultrasound》2002,43(6):568-575
Two-dimensional (2-D) echocardiographic measurement of the left atrium (LA) has the potential to be more accurate than the standard M-mode method, because the LA body can be measured. We evaluated a 2-D method for measuring LA and aorta (AO) in a right parasternal short-axis view and compared it to the M-mode method. An index for LA size (LA/AO) was calculated in 166 cavalier King Charles spaniels, 56 normal and 110 dogs with mitral regurgitation (MR) of varying degrees secondary to chronic valvular disease. In normal dogs, the AO-2-D and LA/AO-2-D did not correlate to body weight (BW) or BW2; whereas, all M-mode values and the LA-2-D were significantly (p < .05) related to both BW parameters. In normal dogs, there was no difference between M-mode and 2-D indices. For all dogs (normal and dogs with MR) there was an 11% bias between the M-mode and 2-D index with the LA/AO-2-D being higher than the LA/AO-M. The association between the mean and the difference of the indices demonstrated a quadratic relationship. Dogs with a mean LA/AO of 2.0-2.5 showed the largest difference between the two indices. Small values for the 2-D coefficients of variation for respiration and stage of diastole were found; 3.4 and 3.1%, respectively. The 2-D index is more sensitive to LA enlargement than the M-mode index.  相似文献   

3.
ObjectivesThe objectives of this study were (1) to assess the potential effect of body weight (BW), age, and gender on the most commonly used echocardiographic and conventional Doppler variables in a large population of healthy Cavalier King Charles Spaniels (CKCS), and (2) to establish the corresponding reference intervals (RI).Animals134 healthy adult CKCS.MethodsUltrasound examinations were performed by trained observers in awake dogs. M-mode variables included left ventricular (LV) end-diastolic and end-systolic diameters, LV free wall and interventricular septal thicknesses at end-diastole and end-systole, and LV fractional shortening (FS%). The left atrium (LA) and aortic (Ao) diameters were measured using a 2D method, and the LA/Ao was calculated. Pulsed-wave Doppler variables included peak systolic aortic and pulmonary flow velocities, mitral E and A waves, and E/A ratio. Effects of BW, age, and gender on these 15 variables were tested using a general linear model, and RIs were determined by applying the statistical procedures recommended by the Clinical and Laboratory Standards Institute.ResultsA significant BW effect was observed for all variables, except LA/Ao, FS%, and mitral E/A ratio. A significant but negligible effect of gender and age was also observed for 5/15 and 4/15 of the tested variables, respectively. Only the BW effect on M-mode variables was considered as clinically relevant and the corresponding regression-based RIs were calculated.ConclusionsBody weight should be taken into account when interpreting echocardiographic values in CKCS, except for LA/Ao, FS%, and mitral E/A ratio.  相似文献   

4.
For echocardiography to become a reliable tool for the diagnosis, monitoring and prognosis of cardiac diseases in cattle, it is necessary to determine normal values of echocardiographic variables and their changes during the growth of healthy animals. In this study, 53 echocardiographic protocols were collected from 17 healthy Friesian calves during their period of growth. The protocol consisted of the measurement or calculation of 10 dimensional and six functional variables from M-mode long axis views of the heart. The relationships between these variables and age, body-weight and body surface area were analysed. Most of the dimensional parameters increased significantly with body size and were best predicted by an allometric regression. However, the functional indices did not change with growth, and the normal values obtained in this study may be applied to calves of any body weight.  相似文献   

5.

Introduction

To report normal echocardiographic variables from a population of healthy Salukis in North America.

Animals

The study included 83 healthy adult Salukis from North America with structurally normal hearts.

Methods

All animals underwent a full physical examination and two-dimensional, M-mode, and Doppler echocardiography using the right parasternal and left apical views with the left ventricular volumes calculated using the Simpson's method of discs. Echocardiographic variables were compared among sex, body surface area, and body weight (BW) using linear regression. The 95% predictive intervals were calculated for both unadjusted and BW-adjusted data.

Results

No relationship between sex and the echocardiographic variables was noted. Predictive intervals for echocardiographic variables are presented for 22 echocardiographic variables. Linear regression suggested that 16 of those variables were associated with BW. The 95% predictive intervals of echocardiographic variables adjusted for BW are reported.

Conclusions

The data from this study provide breed-specific echocardiographic reference values for Salukis.  相似文献   

6.
Allometric scaling of M-mode cardiac measurements in normal adult dogs   总被引：1，自引：0，他引：1  
Indices for M-mode measurements in dogs usually have been based on the assumption that a linear relationship exists between these measurements and body weight (BW) or body surface area (BSA). The relationships between the geometry of 3-dimensional objects do not support this assumption. The purposes of this study were to retrospectively examine M-mode data from a large number of dogs of varying sizes and breeds that were examined by a large number of ultrasonographers, to use the allometric equation to determine the appropriate BW exponent required to predict these cardiac dimensions, and to determine normal mean values and prediction intervals for common M-mode variables. Linear regression analyses of data from 494 dogs (2.2-95 kg) revealed a good correlation between M-mode measurements and BW after logarithmic transformation of the data (r2 = .55-.88). Most variables were most closely related to an index of body length, BW(1/3), although the exponent that best predicted diastolic and systolic left ventricular wall thicknesses was closer to 0.25. No variable indexed well to BW or BSA. With these data, appropriate mean values and prediction intervals were calculated for normal dogs, allowing veterinarians to correctly and appropriately index M-mode values. The equations developed from this study appear to be applicable to adult dogs of most breeds.  相似文献   

7.
Gentamicin sulfate, equivalent to 4 mg of gentamicin base/kg of body weight, was administered IV to 6 Thoroughbred foals on day 1 (12 to 24 hours of age) and at 5, 10, 15, and 30 days after birth. On day 40 after parturition, gentamicin was given to the mares at a dosage similar to that used in foals. Decay of serum gentamicin concentrations was best described by a 2-compartment model. Among foals, the overall elimination rate constant at 30 days of age was significantly (P less than 0.05) greater than at days 1, 10, and 15. There was, however, no difference in the overall elimination rate constant between foals and mares. The volume of distribution (Vd), determined on the basis of total area under the disposition curve, did not change between day 1 and day 30. Mean values of Vd of foals were between 1.5 and 2.5 times higher than the mean Vd of the mares; however, only values from the foals at days 5 and 10 were significantly greater. Both age and interindividual differences were reflected in the total body clearance (ClB) of gentamicin. Total body clearance of gentamicin of foals on day 1 was less than that of foals on days 5, 10, and 30. Additionally, C1B of gentamicin on day 15 was less than that on day 30. There was no significant difference between ClB of foals and mares except for the day-30 group, which had a higher clearance rate than did the adults. Protein binding of gentamicin was less than 30% in all groups, and there were no apparent age-related differences.  相似文献   

8.
Two-dimensional echocardiography (2DE) was performed on 22 unsedated Thoroughbred and part Thoroughbred horses weighing between 411 and 650 kg to establish normal reference values for 2DE measurements. Animals stood during examinations performed with a 3.5 MHz mechanical sector transducer using various transducer positions and tomographic planes. Right ventricular diameter (RVD), ventricular septal thickness (VSTh), aortic diameter (AoD), area of the chordal lumen of the left ventricle (CTA), left ventricular diameter (LVD) and left atrial diameter (LAD) were determined at ventricular end-diastole (Ed) and/or end-systole (Es). Fractional shortening (FS) of the left ventricle and end-systolic left atrial to aortic ratio (LAD-Es:AoD-Es) also were calculated. Echocardiographic data were related to body weight by linear regression analysis. Intra-observer variability was checked in five horses by measuring each parameter during each of 10 consecutive cardiac cycles. The 2DE data were compared with M-mode values in published reports. In the 18 horses whose weight did not exceed 551 kg, repeatable recordings of good quality were obtained, and 2DE measurements could be made using intra-cardiac reference points. Increasing body weight proved to impose substantial limitations on measurements taken with the available machine and transducer. This problem might be overcome by using probes of lower frequency or equipment with higher quality image display at greater depth. The following parameters correlated significantly to body weight: VSTh-Es (r = 0.69; P less than 0.01). AoD-Es (r = 0.64; P less than 0.01) and CTA-Es (r = 0.84; P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

9.
Twelve newborn pony foals underwent cardiovascular examinations (auscultation, arterial blood pressure measurements, electrocardiograms and M-mode echocardiograms) on their first day of life and then on Days 7, 14, 21, 30, 60 and 90. An age dependent, statistically significant, rapid increase of the arterial blood pressure in the first month was documented together with a slower decrease of the resting heart rate after two and three months of life. Innocent soft systolic murmurs were audible over the left heart base in a large number of the foals. The electrocardiograms showed age dependent increases of the PR-, QRS- and QT- intervals and a trend of the mean electrical axis in the frontal plane to rotate towards the left side. The ventricular dimensions, measured by M-mode echocardiography, increased with the growth of the pony foals. Linear regression equations were calculated for the right and left ventricular internal dimensions in relation to body weight (bwt). The other echocardiographic parameter had low correlations with bwt.  相似文献   

10.

Introduction

The aim of this study was to establish echocardiographic reference values for the equine species using allometric regression equations based on body weight (BW) and thoracic circumference (TC).

Animals

A total of 239 horses or ponies were studied, including 65 warmbloods, 33 Standardbreds, 41 Thoroughbreds, 32 Arabian horses, 28 draft horses, and 40 ponies aged from 1 day to 30 years, weighing from 18 to 890 kg, with no evidence of cardiac disease.

Methods

For each horse or pony, a two-dimensional and M-mode echocardiography was performed. Within each breed, the relationships between BW or TC and echocardiographic dimensions were examined using power regression equations. Predictions and their 95% prediction intervals were calculated for the echocardiographic measurements.

Results

Within each breed, all echocardiographic measurements showed a significant and positive relationship with a high coefficient of determination for the estimation of the regression equations using BW and TC as the main explanatory variables. Breed-specific power regression equations as well as the 95% prediction intervals were calculated for each echocardiographic measurement as a function of BW and TC.

Conclusions

In the future, the body size-corrected and breed-specific echocardiographic reference values calculated in the present study could be used to discriminate between normal and abnormal values in a given animal.  相似文献   

11.
Body weight, heart rate, and 19 M-mode echocardiographic variables were measured in 41 nonanesthetized healthy cats. Estimated limits were determined for the echocardiographic variables, and each variable was then correlated to body weight, heart rate, and the 18 other variables. A significant (P less than 0.05) positive correlation to body weight was found with aortic diameter, left atrial dimension, septal and left ventricular systolic and left ventricular diastolic wall thicknesses, and left and right ventricular diastolic and right ventricular systolic internal dimensions. Significant inverse correlation (P less than 0.05) to heart rate was found with body weight, left ventricular systolic and diastolic and right ventricular systolic internal dimensions, left atrial dimension, left atrial dimension to aortic ratio, mitral valve E point to ventricular septal separation, and left ventricular ejection time. Left ventricular shortening fraction in the short axis and velocity of circumferential fiber shortening were significantly correlated (P less than 0.05) to heart rate. Significant correlation (P less than 0.05) was also found between many echocardiographic variables.  相似文献   

12.
ObjectivesTo investigate the dependence of echocardiographic ratio indices (ERIs) on age, body weight (BW) and breed/study group using individually contributed and published summarized data in dogs.BackgroundERIs allow for narrow prediction intervals of M-mode echocardiographic measurements in generic adult dogs. Breed and age-specific differences have not been examined systematically using ERI methods.Animals, materials and methodsIndividual M-mode measurements were contributed by 15 published investigators from 661 dogs, allowing direct calculation of ERIs and summary statistics for each of these breed/study groups. M-mode ERI summary statistics were estimated from published summaries of 22 additional groups that included 527 adult and 36 growing dogs. Individual two-dimensional (2DE) left atrial (LA) and aortic root (Ao) measurements were contributed from 36 dogs. ERIs were analyzed for dependence on BW, breed/study group and age.ResultsThe majority of variation among ERIs was due to differences in the breed or study technique with comparatively little dependence on BW. Age dependence of ERIs was seen in the early growth phases of young dogs, but expected values for each ERI became static long before maturity, roughly at 10–12 weeks of age. ERIs derived from individual 2DE LA and Ao measurements showed no significant dependence on BW.ConclusionsERIs are well normalized for body size and may be useful for clinical evaluation of individuals, prediction of expected M-mode and 2DE cardiac dimensions, and investigation of age or breed-specific cardiac shape changes.  相似文献   

13.
The objectives of this study were to evaluate the optimal body size variable, and to determine mathematical model that best fits echocardiographic measurements to body size in the equine species. One hundred fifty horses of various breeds, aged 1 week to 17 years, body weight (BW) 38-890 kg, and free from cardiac disease were used in this study. Based on their age (ie, younger or older than 2 years), animals were separated into two groups. In each horse, the BW, height at withers (HT), thoracic circumference (TC), and the body length were measured; the body surface area was calculated; and a standard two-dimensional and M-mode echocardiography was performed allowing classic cardiac measurements to be taken. Correlations between each echocardiographic measurement and each of the anthropometric variables were assessed via a Pearson's product-moment analysis and using linear, logarithmic, and power regression analysis in all animals and within the two groups. The dimensional, but not functional, echocardiographic measurements showed a close correlation with all body size variables, especially during growth. The relationship between cardiac measurements and body size was best described using power regression models with TC as the anthropometric variable, but the relationship was also very accurately described using BW, body surface area, or body length. In the equine species, dimensional echocardiographic reference values should be established using power regression equations on TC. Such a correction for body size could increase the diagnostic value of echocardiography in equine cardiology.  相似文献   

14.
Reasons for performing study: Few studies have evaluated the athletic prognosis of foals affected by gastrocnemius disruption. Objective: To examine the diagnosis and management of gastrocnemius disruption in Thoroughbred (TB) foals, determine short‐term survival rate and assess future racing performance. The hypothesis was that Thoroughbred foals with gastrocnemius disruption are able to perform as racehorses comparably to their age matched maternal siblings. Methods: The medical records of foals diagnosed with gastrocnemius muscle disruption were reviewed. Information on training and racing was acquired from published works and race records. Paired t tests were utilised to compare performance variables of affected racehorses to their maternal siblings in starts, earnings and earnings/start for their 2‐ and 3‐year‐old racing seasons. Fisher's exact tests were employed to determine the association between sex, limb affected, age on admission, degree of caudal reciprocal apparatus dysfunction, concurrent disease, antibiotic therapy, complications, abscess formation and likelihood of entering training or starting a race. Results: Sample size was too small to detect significant differences in performance variables between affected horses and controls. Of 28 foals, 17 (61%) presented with concomitant illness; foals without concurrent disease were more likely to achieve race training or start a race (P = 0.04); 23 (82%) were short‐term survivors defined as survival to discharge. Of these 23 survivors, 7 were aged <2 years at the time of the study. Eighty‐one percent (13/16) of the survivors that were of racing age were in training or had started a race. Conclusions: In this population, 82% of TB foals affected with gastrocnemius disruption were able to achieve training or start a race. Foals presenting for gastrocnemius disruption have a high prevalence of concurrent disease processes. Potential relevance: The assessment of athletic prognosis and treatment complications provides useful information to clinicians treating gastrocnemius muscle disruption in foals and making recommendations to clientele.  相似文献   

15.
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16.
The effect of age on the pharmacokinetics of chloramphenicol was determined after IV administration of chloramphenicol sodium succinate (25 mg/kg of body weight) to 6 foals at 1 day and 3, 7, 14, and 42 days of age. The disposition of chloramphenicol was best described, using a two-compartment open model in all foals at all ages evaluated. Significant age-related changes were observed in values for the major kinetic terms describing the disposition of chloramphenicol in foals; the greatest changes were observed between 1 day and 3 days of age. The mean +/- SD value for elimination rate constant (beta) for chloramphenicol in 1-day-old foals (0.131 +/- 0.06 h-1) was significantly (P less than 0.005) lower than the value in 3-day-old foals (0.514 +/- 0.156 h-1), and both values were significantly (P less than 0.05) lower than values for beta in 7-, 14-, and 42-day-old foals. With increasing age, the increase in the mean value for beta resulted in decrease in the harmonic mean elimination half-time (t1/2 beta) for chloramphenicol, from 5.29 hours in 1-day-old foals to: 1.35 hours in 3-day-old foals; 0.61 hour in 7-day-old foals; 0.51 hour in 14-day-old foals; and 0.34 hour in 42-day-old foals. At 1, 3, and 7 days of age, values for t1/2 beta of chloramphenicol in a premature foal born after parturition was induced with oxytocin, were considerably longer than comparable t1/2 beta values for term foals born naturally.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

17.
OBJECTIVE: To determine whether logarithmic and polynomial models are superior to simple linear models for predicting reference values for M-mode echocardiographic variables in dogs with a wide range of body weights. ANIMALS: 69 apparently healthy adult male and female dogs of various breeds, ages (range, 1 to 12 years; median, 3.5 years), and body weights (range, 3.9 to 977 kg; median, 25.4 kg). PROCEDURE: Echocardiographic M-mode measurements of the interventricular septum, left ventricular dimension (LVD), left ventricular wall, aorta, and left atrium were obtained. Simple linear, second-order polynomial, third-order polynomial, and logarithmic regression models were determined by use of the least-squares method to describe the relationship between M-mode measurements and body weight. Differences in adjusted R2 values of logarithmic and polynomial models were tested for significance of contribution, compared with the simple linear model. RESULTS: Significant differences in adjusted R2 were found when comparing simple linear with logarithmic or polynomial models for LVD-diastole, LVD-systole, aorta, and left atrium. Differences in adjusted R2 between second-order polynomial, third-order polynomial, and logarithmic models were not significant for any M-mode measurement. CONCLUSIONS AND CLINICAL RELEVANCE: In this study, logarithmic or second-order polynomial models predicted reference values of M-mode measurements for size of the cardiac chambers better than simple linear models for dogs with a wide range of body weights. Logarithmic and polynomial models were not superior to simple linear models for M-mode measurements of cardiac wall thickness.  相似文献   

18.
AIMS: To determine the chemical body composition of Thoroughbred foals born in two consecutive years, and to investigate several techniques used to predict body composition in foals born in the second year, with particular reference to fat. METHODS: The chemical composition of 20 foals at around 160 days of age, born in two years, was determined. In vivo techniques to predict body composition were assessed in 23 foals born in Year 2, before and after euthanasia; 10 of these foals were used for chemical body composition analysis. Techniques to assess body composition in vivo included liveweight (LW), overall and regional condition scores, ultrasonic fat thickness measurements over the ribs and rump, linear measurements and bioelectrical impedance analysis. Correlations were determined between ultrasonic fat thickness, and bioelectrical impedance analysis, before and after euthanasia. Stepwise regression analysis was used to determine the relationships between in vivo techniques used to assess body composition and the chemical body composition of 10 animals. RESULTS: Foals used for analysis of chemical composition weighed between 220.5 and 260.0 kg before euthanasia. Fat content ranged from 5.5-13.0% of the partial empty bodyweight (LW less head, gastrointestinal contents, distal limbs and skin). Fillies had significantly more fat mass and percentage fat than colts (p=0.031 for both measurements). The mean chemical composition of the fat-free partial empty body was 73.2% (SD 0.6) water, 22.7% (SD 0.9) protein, and 4.1% (SD 0.4) ash. Most of the variation in the concentration of empty body water was associated with variation in the concentration of fat (p<0.001). The live animal overall condition scores were correlated with fat mass and concentration (p=0.006 and p=0.013, respectively; n=10). Condition score over the rib region was highly correlated with fat mass and fat concentration (p=0.004 and p<0.001; n=10). Ultrasound measurements taken 10 cm cranial to the tailhead and 4 cm from midline, used to assess the thickness of rump fat, were correlated with condition score (p=0.001), and explained 71% of the variation in body fat mass (p=0.002; n=10).Nearly 50% of the variation in fat-free mass and partial empty body water mass were associated with variation in the impedance indices calculated from length and bioelectrical impedance analysis measurements (p=0.023 and p=0.026, respectively; n=10). CONCLUSIONS: At around 42% of expected mature weight, fillies were significantly more fat than colts. Condition scores were correlated with partial empty body fat mass, and there was a trend for higher scores in fillies compared to colts. Much of the variation in water or protein mass of the partial empty body could be explained by variations in LW. CLINICAL RELEVANCE: Measurements of LW, rump fat and condition score are useful predictors of the chemical composition of foals at 5 months of age.  相似文献   

19.
Ragan  Adams  MA  DVM  Paul  Poulos  DVM  PhD 《Veterinary radiology & ultrasound》1988,29(5):217-222
A skeletal ossification index (SOI) was devised to standardize the radiographic evaluation of the carpal and tarsal regions of newborn foals (less than two weeks of age). This index was based on two radiographic views of a carpus and a tarsus. Four grades of cuboidal bone ossification were discerned: Grade 1 foals had some cuboidal bones with no ossification; Grade 2 was assigned when all cuboidal bones had radiographic evidence of some ossification; in Grade 3 the bones were small and round; in Grade 4 the cuboidal bones were shaped like the adult counterparts. Radiographs were taken of 24 neonatal foals of various gestational ages (range, 297–374 days). The relationships between the SOI and two measures of newborn foal developmental maturity, gestationai age and body weight, were assessed. There was no relationship between the sex of the foal and the SOI, but there was a relationship between the SOI and the gestational age (one-tailed Spearman's rank correlation coefficient, r = 0.748) and between the SOI and body weight (r = 0.77) for the 24 foals. For the ten foals with gestational ages less than 320 days, the relationship between body weight and the SOI was significant (r = 0.953), but the relationship between gestational age and the SOI was not significant (r = 0.605). The degree of ossification of the bones of neonatal foals that are born prematurely (< 320 days of gestation) or are "small-for-gestational age" at birth may be incomplete, and we suggest that radiographs of these regions should be made to assess ossification in foals in these two high risk groups.  相似文献   

20.
The effects of dam parity, age at weaning, and preweaning diet were examined in the ontogeny of serum insulin-like growth factor-I (IGF-I) concentrations in foals. Foals born to 13 primiparous and 19 multiparous draft-cross mares were weighed and bled near birth. About one-half of the foals in each group were weaned early (about 13 wk old); the remaining foals were weaned late (about 16 wk of age). Pooled values for serum IGF-I concentrations between birth and 17 wk of age were higher (P < 0.065) for foals born to multiparous (386 ng/ml) than to primiparous mares (237.5 ng/ml). Colts (378 ng/ml) had higher (P < 0.05) serum IGF-I concentrations than fillies (254.5 ng/ml), regardless of dam parity. Colts (173.5 kg) also tended (P = 0.12) to be heavier than fillies (159.2 kg). Weaning, whether at 13 or 16 wk of age, reduced (P < 0.05) growth rates and serum IGF-I concentrations. Serum IGF-I values recovered to preweaning values within 1–3 wk postweaning concurrent to an improved weight gain. Fifteen 1-d-old foals in a second study were fed milk replacer for 7 wk and were compared with five foals that nursed their mares for 8 wk. During the first 2 wk, replacer-fed foals (0.46 kg/d) did not gain as rapidly (P < 0.03) as mare-nursed foals (1.73 kg/d). The associated serum IGF-I values for replacer foals (139.4 ng/ml) were lower (P < 0.0001) than values for mare-nursed foals (317.4 ng/ml). Despite similarity in gains for both groups thereafter, serum IGF-I concentrations of replacer-fed foals were only 36 and 60% of values obtained for mare-nursed foals at 8 (weaning) and 18 wk of age, respectively. The intrinsic differences between mare-nursed and milk-replacer foals in serum IGF-I concentrations persisted to 1 yr of age despite similarities in dietary management and body weight of the foals. At 1 yr of age, the serum IGF-I concentration of mare-nursed foals (1,203 ng/ml) was 48% higher than that of replacer-fed foals (815 ng/ml). These data indicate that dam parity, sex of foal, and preweaning nutrition affect the ontogeny of serum IGF-I concentration in the foal. The chronic, persistent difference in serum IGF-I values created by the early nutritional management of growing animals has implications in the interpretation of longitudinal serum IGF-I studies in all species.  相似文献   

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