Iron deficiency in stabled Dutch warmblood foals

Forty-three Dutch Warmblood foals were divided at random into 3 rearing groups immediately after birth: a box-rest group, a box-rest with exercise group, and a pasture group. All stabled foals (box-rest and exercise groups) were fed freshly cut grass harvested from the same pastures on which the pasture group foals were grazing. Blood samples were obtained monthly for CBC and biochemical analyses. At 1-3 months of age, the foals at pasture were active but the foals in the box-rest and exercise groups were listless. Mean hemoglobin concentrations, PCVs, blood iron concentrations, and saturation of total iron binding capacity were significantly lower (P < .05) in the box-rest group (11.3+/-1.2 g/dL, 33+/-3%, 123+/-67 microg/dL, and 18+/-9%) and the exercise group (11.6+/-1.5 g/dL, 34+/-4%, 101+/-61 microg/dL, and 15+/-10%) compared with the pasture group (14.0+/-0.8 g/dL, 42+/-3%, 212+/-67 microg/dL, and 32+/-10%). Oral supplementation of iron to all foals resulted in significant increases in the values of these variables in the box-rest group and exercise group at 4-5 months of age, and the stabled foals were as active as the foals at pasture. In the pasture group, no significant changes occurred. Management practices clearly influence the iron state in young growing foals from 1 to 3 months of age, and although not a frequent cause of anemia in the horse, an absolute deficit of body iron may occur in stabled foals fed freshly cut grass.     

Effects of exercise on biomechanical properties of the superficial digital flexor tendon in foals.

OBJECTIVE: To determine the effects of exercise on biomechanical properties of the superficial digital flexor tendon (SDFT) in foals. ANIMALS: 43 Dutch Warmblood foals. PROCEDURE: From 1 week until 5 months of age, 14 foals were housed in stalls and not exercised, 14 foals were housed in stalls and exercised daily, and 15 foals were maintained at pasture. Eight foals in each group were euthanatized at 5 months, and remaining foals were housed together in a stall and paddock until euthanatized at 11 months. After euthanasia, SDFT were isolated and fit in a material testing system. Mean cross-sectional area (CSA) was measured and traction forces recorded. Normalized force at rupture (force(rup)), normalized force at 4% strain, strain at rupture, stress at 4% strain (stress(4%stain)), and stress at rupture were compared among and within groups. RESULTS: At 5 months, mean CSA and normalized force(rup) were significantly greater and stress(4%strain) significantly less in the pastured group, compared with the other groups. At 11 months, CSA and normalized force(rup) were not significantly different among groups, because force(rup) increased significantly from 5 to 11 months in the nonexercised group and decreased significantly in the pastured group. CONCLUSIONS AND CLINICAL RELEVANCE: Exercise significantly affected the biomechanical properties of the SDFT in foals. Evenly distributed moderate- and low-intensity exercise at a young age may be more effective for development of strong, flexible tendons in horses than single episodes of high-intensity exercise superimposed on stall rest. This effect may impact later susceptibility to SDFT injury.     

Effects of exercise on the diameter of collagen fibrils in the central core and periphery of the superficial digital flexor tendon in foals

OBJECTIVE: To determine the effects of exercise on collagen fibril diameter distribution in the superficial digital flexor tendon (SDFT) of foals. ANIMALS: 43 Dutch Warmblood foals. PROCEDURE: From 1 week until 5 months of age, group-1 foals (n = 14) were housed in stalls and not exercised, group-2 foals (14) were housed in stalls but were exercised, and group-3 foals (15) were maintained at pasture. Biopsy specimens were collected from the SDFT at 2 months, and 8 foals in each group were euthanatized at 5 months. Remaining foals were housed together in a loose stall and paddock until euthanatized at 11 months. After euthanasia, specimens were collected from the SDFT; all specimens were analyzed by use of electron microscopy. Collagen fibrillar index (CFI), mass average diameter (MAvD), and area dependent diameter (ADD) were compared among groups. RESULTS: Exercise-related differences in fibril distribution were not detected among groups at 2 months. At 5 months, ADD in peripheral specimens was significantly greater in group 1 than group 3. At 11 months, MAvD in core specimens was significantly less in group 3, compared with the other groups. However, in peripheral specimens, MAvD was significantly less in groups 2 and 3. CONCLUSIONS AND CLINICAL RELEVANCE: Collagen fibril restructuring in the SDFT of foals is in part an exercise-driven process. Withholding exercise may cause a delay in fibril development that can be partially overcome by increasing exercise at a later age. Exercise type may also affect remodeling of the SDFT in foals.     

Association of growth, feeding practices and exercise conditions with the prevalence of Developmental Orthopaedic Disease in limbs of French foals at weaning

Developmental Orthopaedic Disease (DOD) in limb joints of horses is frequent and is a common cause of pain and lameness. DOD is a multifactorial disease involving genetics, growth, feeding practices and exercise conditions leading to joint injuries. However, there is no clear understanding of the contribution of each factor. The aim of this cohort study was to assess the adjusted effects of breed and gender, growth, feeding practices and exercise conditions on the prevalence of DOD in the limbs of foals at weaning and on the prevalence restricted to osteochondrosis (OC).Twenty-one farms in Normandy, France, were convenience sampled and enrolled in a cohort study. The study sample consisted of 401 foals from 3 breeds, followed from the 8th month of pregnancy of the mares until weaning period at approximately 6 months of age of the foals. Stud farms were regularly visited to collect growth, feeding practices and exercise conditions data. The carpus, the front and hind digits, the hock and the stifle of the foals were X-rayed at the end of follow-up. Foals were categorised as affected or unaffected by DOD or by OC. Two mixed-effects logistic regression models were used to determine risk factors for DOD or OC, adjusting for clustering by farm.Of the 378 foals with complete data, 47% (95% CI: 42–52) were affected by DOD and 36% (95% CI: 31–41) by OC. Risk was significantly increased for DOD and for OC in Warmblood foals compared to Thoroughbreds (OR 2.8; 95% CI: 1.2–6.5 for DOD, OR 2.9; 95% CI: 1.1–7.5 for OC), in foals with a high wither height at 30 days of age, and in foals with a rapid increase of wither height (for DOD only). Exercise conditions such as large area of pasture, some irregular exercise, or some batch changes were also significant risk factors for DOD or OC. No association was found with quantitative feeding practices; it was likely due to the limited variability of horse regimens and to the partial inclusion of nutritional effects in other factors such as breed and growth. In order to reduce the prevalence of DOD or OC in foals, following the growth and reducing nutritional supply in subjects growing fast, limiting the pasture areas offered and providing a regular exercise to foals seems appropriate. To our knowledge, to date the assessment of adjusted effects of potential risk factors for DOD has never been proposed.     

Effect of exercise on development of capillary supply and oxidative capacity in skeletal muscle of horses

OBJECTIVE: To determine whether postnatal development of oxidative capacity and capillary supply of skeletal muscle is affected by various movement regimens in horses. ANIMALS: 35 foals. PROCEDURES: Dutch Warmblood foals were allocated into 3 groups (box stall rest, box stall rest with training, and free pasture exercise). Training comprised an increasing number of gallop sprints from 1 week after birth to 22 weeks of age. From 22 to 48 weeks, the 3 groups were combined and allowed to exercise freely. Capillary supply (diffusion index [ie, area supplied by 1 capillary]), citrate synthase (CS) activity, and succinate dehydrogenase (SDH) activity were measured in biopsy specimens of deep gluteus medius muscle. RESULTS: During the first 22 weeks, diffusion index increased in all 3 groups (the training and pasture groups had a smaller increase, compared with the box stall rest group), total SDH activity increased in the training and pasture groups and decreased in the box stall rest group, and CS activity decreased in all groups. The effect of the various movement regimens on the diffusion index remained after the groups were combined. CONCLUSIONS AND CLINICAL RELEVANCE: Withholding of exercise had a negative effect on the capillary supply (ie, diffusion index increased) that remained after box stall rest was discontinued and on oxidative capacity. Box stall rest with training prevented the negative effects and eventually had the same positive effect as pasture exercise.     

The variations of white blood cell count in Lipizzan horses

Total and differential leucocyte counts (lymphocytes, neutrophils, monocytes, eosinophils and basophils) were measured in 140 stallions, 101 mares and 25 foals of Lipizzan breed. The values fell in the normal ranges for warm-blooded horses. Differences between mares and stallions were not significant with the exception of foals, having higher white blood cell, neutrophil, lymphocyte, monocyte and basophil values in females than in males. Foals exhibited an age-related increase of total leucocyte count during the first 4 months of life, accompanied by a decrease in neutrophil and increase in lymphocyte and eosinophil counts. In mares and stallions, the total number of leucocytes, lymphocytes, monocytes and basophils significantly decreased but the number of neutrophils and eosinophils remained almost unchanged with age gain.     

Early exercise advances the maturation of glycosaminoglycans and collagen in the extracellular matrix of articular cartilage in the horse

REASON FOR PERFORMING STUDY: Training at a very young age may influence the characteristics of the collagen network of articular cartilage extracellular matrix (ECM) in horses. OBJECTIVES: To investigate whether increasing workload of foals results in significant changes in the biochemical composition of articular cartilage ECM. METHODS: Thoroughbred foals (n = 33) were divided into 2 different exercise groups from age 10 days-18 months. One group (PASTEX; n = 15) was reared at pasture; the other (CONDEX; n = 18) underwent a specific additional training programme that increased workload by 30%. At mean age 18 months, 6 animals from each group were subjected to euthanasia. The proximal articular surface of the proximal phalanx of the right hindlimb was examined for the presence of damage using the cartilage degeneration index (CDI). Samples were taken from 2 sites with known different loading patterns. Slices were analysed for DNA, glycosaminoglycans (GAG), collagen and post translational modifications of collagen (formation of hydroxylysylpyridinoline [HP] and pentosidine crosslinks, and hydroxylysine [Hyl]), and exercise groups and different sites compared. RESULTS: There were no differences in CDI between PASTEX and CONDEX animals, indicating the absence of extra joint damage due to the exercise regimen. There were site-related differences for most biochemical variables, corroborating earlier reports. All biochemical variables showed differences between PASTEX and CONDEX groups at one of the sites, and some at both. GAG and collagen levels were lower in the CONDEX group whereas Hyl, HP crosslinks and pentosidine crosslinks were higher. CONCLUSIONS AND POTENTIAL RELEVANCE: A measurable effect of the conditioning exercise was demonstrated. The margin between too much and too little work when training foals may be narrower than intuitively presumed.     

Changes in fibre type composition of gluteus medius and semitendinosus muscles of Dutch Warmblood foals and the effect of exercise during the first year postpartum

In order to obtain broader insights into the equine musculoskeletal system, we studied the fibre type composition of 2 locomotory muscles in biopsies from Dutch Warmblood foals taken at 3 different ages in the first year postpartum. The muscle fibre types were determined histochemically as well as immunohistochemically. ATPase-characterised IIB fibres appear to express either IId or type lIa plus IId myosin heavy chain (MHC). A high percentage of fibres classified as IIA with ATPase expressed both fast types of MHC. The type I classification by the 2 methods matched almost completely. There was an increase with age of fibres expressing I and IIa MHC in the gluteus medius. At the same time, there was a decrease of fibres expressing IId MHC and fibres co-expressing MHC IIa and IId. MHC expression of the semitendinosus muscle did not change over time at first, but from age 22-48 weeks there was a decrease in the percentage of type IId fibres. In general, the gluteus medius contained more type I fibres but fewer type IId fibres compared to the semitendinosus. At most ages the fibre type compositions of both muscles correlated with one another. To examine the effect of exercise, one-third of the foals were given box rest, one-third received training and one-third kept at pasture during the first 22 weeks of life. The 3 exercise groups differed in their fibre type composition; however, these differences could not be attributed to the effect of exercise.     

Adaptation of Equine Locomotor Muscle Fiber Types to Endurance and Intensive High Speed Training

Skeletal muscle constitutes the largest organ system in the mammalian body and is essential for movement and force generation. Muscle tissue has the unique ability to adapt and remodel with regular exercise. Adaptation of equine contractile apparatus to exercise training with a different character occurs at the structural to the cellular and molecular levels and depends on age, breed, and sex. In Andalusian and Arabian horses from 3 months to 24 years of age, it was found that the mean cross-sectional area occupied by IIA and IIX fibers was greater in stallions than in mares. In muscle of Dutch Warmblood foals from birth to 1 year of age, a significant number of fibers coexpress either developmental and type IIa or cardiac–alpha and type I myosin heavy chain (MyHC) isoforms. Endurance training results in increased mitochondrial density, capillary supply, changes in key metabolic enzymes, and increased maximal oxygen uptake and promotes a transition from type II to type I muscle fiber. In horses, prolonged aerobic exercise training has been shown to induce a further decline in the percentage of type IIx MyHC isoform expression and an increase of type I and IIa MyHC isoform expression. Short-duration, high-intensity exercise training stimulates type IIA and hybrid (IIA/IIX) fibers. Therefore, intensive high-speed trotting facilitates muscle fiber hypertrophy and increases the oxidative capacity of type IIX fibers.     

Evaluation of consistency of jumping technique in horses between the ages of 6 months and 4 years

OBJECTIVE: To determine whether differences in jumping technique among horses are consistent at various ages. ANIMALS: 12 Dutch Warmblood horses. PROCEDURE: Kinematics were recorded during free jumps of horses when they were 6 months old (ie, no jumping experience) and 4 years old (ie, the horses had started their training period to become show jumpers). Mean +/- SD height of the horses was 1.40 +/- 0.04 m at 6 months of age and 1.70 +/- 0.05 m at 4 years of age. RESULTS: Strong correlations were found between values from 6-month-old foals and 4-year-old horses for variables such as peak vertical acceleration generated by the hind limbs (r, 0.91), peak rate of change of effective energy generated by the hind limbs (r, 0.71), vertical velocity at takeoff (r, 0.65), vertical displacement of the center of gravity during the airborne phase (r, 0.81), and duration of the airborne phase (r, 0.70). CONCLUSIONS AND CLINICAL RELEVANCE: Although there are substantial anatomic and behavioral changes during the growing period, certain characteristics of jumping technique observed in na?ve 4-year-olds are already detectable when those horses are foals.     

Influence of age of horse on results of quantitative electromyographic needle examination of skeletal muscles in Dutch Warmblood horses

OBJECTIVE: To determine the influence of age on results of quantitative analysis of electromyographic (EMG) needle examination in the subclavian, triceps, and lateral vastus muscles of Dutch Warmblood horses. ANIMALS: 7 healthy young Dutch Warmblood horses (range, 13 to 18 months old), 7 healthy adult Dutch Warmblood horses (range, 4 to 10 years old), and 7 healthy elderly Dutch Warmblood horses (range, 18 to 21 years old). PROCEDURE: An EMG needle examination was performed to evaluate insertional activity, spontaneous activity, and motor unit action potential (MUAP) variables. Although all horses were conscious, young horses were sedated prior to examination. RESULTS: Mean insertional activity in young horses was significantly lower than in elderly horses. Pathologic spontaneous activity was rarely found in young and adult horses but was frequently evident in all muscles in all elderly horses. The MUAP duration and amplitude were significantly lower in all muscles of young horses, compared with values for adult and elderly horses. The MUAP duration and number of phases and turns were significantly lower in adult horses than in elderly horses. Group differences for percentages of polyphasic and complex MUAPs were also found. The 95% confidence intervals for MUAP duration, MUAP amplitude, and number of phases and turns for the subclavian, triceps, and lateral vastus muscles were significantly lower in young horses than in adult or elderly horses. CONCLUSIONS AND CLINICAL RELEVANCE: Age of the horse being examined should be considered when EMG examination is performed.     

The course of some bone remodelling plasma metabolites in healthy horses and in horses offered a calcium-deficient diet

An inquiry was carried out to assess the concentrations of plasma metabolites related to bone remodelling in 21 saddle horses of Warmblood breed aged 4-26 years, five draught horses of Ardennes breed aged 4-10 years, and 10 Ardennes foals aged 9-11 months. They were fed according to normal feeding practice in Belgium. The changes in some bone remodelling plasma metabolite concentrations were studied when an unbalanced diet was offered and later corrected for four Warmblood horses. Bone formation was evaluated by bone alkaline phosphatase (BALP), total alkaline phosphatase (TALP) and osteocalcin (bone gla-protein, OC). Bone resorption was assessed by hydroxyproline (HYP). Total calcium, ionized calcium, phosphorus (P) and 25-hydroxyvitamin D3 [25-(OH)D] concentrations were more or less constant. The comparison of four bone remodelling factors between the Ardennes and Warmblood horses showed higher concentrations in the Ardennes breed. Bone marker concentrations decreased according to age. The correction of the unbalanced Ca : P diet induced inconsistent effects at plasma level. The interpretation of the different bone parameters appeared to be difficult if not associated with other parameters such as a complete anamnesis and clinical examination of the animal in addition to dietary evaluation.     

Effect of gender and exercise on haematological and biochemical parameters in Holsteiner horses

The objective of this study was to assess the influence of exercise of average intensity in the haematological and biochemical values, as well as acidic resistance of erythrocytes in mares and stallions of Holsteiner breed. A total of seventeen horses of Holstein breed (seven mares and 10 stallions aged 6 years) were used in this study. The blood samples were assessed for haematocrit (HCT) value, haemoglobin concentration (HGB), the amount of red blood cells (RBC), white blood cells (WBC), platelets (PLT), leucogram, mean corpuscular haemoglobin concentration (MCHC), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), red cell distribution width (RDW) and platelet distribution width (PDW). Serum concentrations of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) as well as oxidative stress biomarkers were analysed. Stallions showed a significant increase in leucocytes and granulocytes amount, as well as erythrocytes, haemoglobin and haematocrit levels after exercise test. Pre‐exercise level of mean corpuscular haemoglobin concentration was higher in stallions. At the same time, mares showed significant decrease in platelet volume after exercise test. Physical effort in stallions leads to significant increase in aspartate aminotransferase activity. Trained mares and stallions showed a decrease in lipid peroxidation after exercise. Exercise also caused increase in oxidative modified protein of erythrocytes in stallions indicating by exercise‐induced oxidative stress. The resistance of erythrocytes in 0.1 m HCl was similar between females and males. No statistically significant differences in the percentage of haemolysed erythrocytes before and after exercise were observed.     

The influence of exercise during growth on ultrasonographic parameters of the superficial digital flexor tendon of young Thoroughbred horses

REASON FOR PERFORMING STUDY: Conditioning by early training may influence the composition of certain musculoskeletal tissues, but very few data exist on its effect during growth on tendon structure and function. OBJECTIVES: To investigate whether conditioning exercise in young foals would lead to any ultrasonographically detectable damage to the superficial digital flexor tendon or an increase in cross-sectional area (CSA). METHODS: Thirty-three Thoroughbred foals reared at pasture were allocated to 2 groups: control (PASTEX) allowed exercise freely at pasture; and CONDEX, also at pasture, began conditioning exercise from mean age 21 days over 1030 m on a purpose-built oval grass track, for 5 days/week until mean age 18 months. Foals were observed daily, and underwent orthopaedic examination monthly. Ultrasonographic images of the superficial digital flexor tendon (SDFT) at the mid-metacarpal level of both forelimbs were obtained in all foals at ages 5, 8, 12, 15 and 18 months. CSA was validated (r(2) = 0.89) by determining CSA from digital photographs of the transected SDFT surface from 12 of the horses necropsied at age 17.1 months. RESULTS: here was no clinical or ultrasonographic evidence of tendonopathy in either group and the greatest increase in mean CSA in both groups occurred between age 5 and 8 months. Across all age categories, there was no significant difference in mean CSA between the left and right limbs, or colts and fillies; there was a trend towards a larger CSA in the CONDEX group (P = 0.058). CONCLUSIONS: There was no conclusive evidence for a structural adaptive hypertrophy of the SDFT, probably because the regimen was insufficiently rigorous or because spontaneous pasture exercise may induce maximal development of energy storing tendons. POTENTIAL RELEVANCE: A moderate amount of early conditioning exercise against a background of constant exercise at pasture is not harmful to the development of the flexor tendons.     

Influence of Age on Surfactant Isolated from Healthy Horses Maintained on Pasture

Background: Surfactant alterations are described in horses after exercise, anesthesia, and prolonged transport, in horses with recurrent airway obstruction, and in neonatal foals. The effect of horse age or bronchoalveolar lavage fluid (BALF) sample characteristics on surfactant is unknown.
Objectives: To evaluate surfactant phospholipid composition and function in healthy horses, and to investigate the influence of age and BALF sample characteristics on surfactant.
Animals: Seventeen healthy horses 6–25 years of age maintained on pasture year-round.
Methods: BALF was collected by standard procedures and was assessed for recovery volume, nucleated cell count (NCC), and cytology. Cell-free BALF was separated into crude surfactant pellet (CSP) and surfactant supernatant (Supe) by ultracentrifugation. Phospholipid and protein content were determined from both fractions. CSP phospholipid composition was analyzed by high-performance liquid chromatography with an evaporative light scatter detector. Surface tension of CSP was evaluated with a pulsating bubble surfactometer. Regression analysis was used to evaluate associations between age, BALF sample characteristics, and surfactant variables.
Results: Results and conclusions were derived from 15 horses. Increasing age was associated with decreased phospholipid content in CSP but not Supe. Age did not affect protein content of CSP or Supe, or surfactant phospholipid composition or function. Age-related surfactant changes were unaffected by BALF recovery percentage, NCC, and cytological profile.
Conclusions and Clinical Importance: Older horses have decreased surfactant phospholipid content, which might be because of age-related pulmonary changes. Surfactant composition is unaffected by BALF sample characteristics at a BALF recovery percentage of at least 50%.     

Risk factors for the presence and extent of Developmental Orthopaedic Disease in the limbs of young horses: Insights from a count model

Developmental Orthopaedic Disease (DOD) in limb joints is frequent, can cause lameness and is a major cause of economic losses for the horse breeding industry. Studies on risk factors for DOD usually dichotomise the outcome to presence/absence without considering the extent of the disease, which can be appreciated by the number or the severity of the lesions. The aim of this study was to assess the effects of growth, exercise conditions and feeding practices on the number of radiographic findings (RF) of DOD in a cohort of horses, assuming that the risk factors associated with the presence of the disease and the number of RF may differ. We recruited broodmares on 21 stud farms in the Normandy region, France in 2002-2004. The stud farms were visited regularly to collect growth, exercise conditions, and feeding practices data from the end of the gestation to the weaning of the foal. The carpus, the front and hind digits, the tarsus and the stifle of the foals were radiographed at approximately six months of age. Each foal was classified according to the absence (no RF) or presence (≥1 RF) of DOD and to the number of RF. A zero-inflated Poisson model was used to simultaneously determine risk factors for presence/absence and for the number of RF of the disease. The convenience sample consisted of 378 foals, 53.1% of which did not have any RF. The mean number of RF per foal was 1.25 and the variance was 2.80. Comparing to the Poisson, negative binomial, and zero-inflated negative binomial regressions, the zero-inflated Poisson model was found to be best suited for these data. Of the 295 foals with complete data, three risk factors were significantly associated with a higher risk of being affected by DOD: high wither height increase, large group size in pasture and large pasture size. Seven risk factors were associated with the number of RF: wither height at 30 days of age, age of the mare, breed, regularity of exercise, Ca/P level in the mare and foal rations, group size in pasture, and the type and frequency of handling. This study shows that risk factors vary for the presence and extent of DOD, and that the use of a count model achieves a more detailed determination of risk factors for the presence of DOD and for the number of RF of DOD compared to the more conventional dichotomy presence/absence of the disease.     

Specificity and reversibility of the training effects on the concentration of Na+,K+-Atpase in foal skeletal muscle

The purpose of the present study was to determine whether training and detraining affect the Na+,K+-ATPase concentration in horse skeletal muscles, and whether these effects are specific for the muscles involved in the training programme. Twenty-four Dutch Warmblood foals age 7 days were assigned randomly to 3 groups: Box (box-rest without training), Training (box-rest with training: short-sprint) and Pasture (pasture without training). Exercise regimens were carried out for 5 months and were followed by 6 months of detraining. Five of the foals in each group were subjected to euthanasia at age 5 months and the remaining foals at 11 months. Muscle samples were collected from the deep part of the gluteus medius, semitendinosus and masseter muscles. The Na+,K+-ATPase concentration was quantified by [3H]ouabain binding. In the Training group, the concentration of Na+,K+-ATPase in gluteus medius and semitendinosus muscle, but not in masseter muscle, showed a relative increase of 20% (P<0.05) as compared to Box foals. After detraining for the subsequent 6 months, the concentration of Na+,K+-ATPase in semitendinosus muscle remained the same, while that in gluteus medius muscle was reduced by 10%. It is concluded that: 1) short-sprint training for 5 months induced an increase of the Na+,K+-ATPase concentration in gluteus medius and semitendinosus muscles of the foal. Interestingly, this effect persisted during the 6 months of the detraining period. Whether the higher Na+,K+-ATPase concentration due to training of young foals leads to a better athletic performance when they become mature still needs to be established; 2) the factors that initiate an increase in Na+,K+-ATPase concentration following training are likely to be located in the muscle itself and 3) the training effect may last for several months after returning to normal activity, especially in muscles containing a high percentage of fast-twitch fibres.     

Evaluation of serum concentrations of biomarkers of skeletal metabolism and results of radiography as indicators of severity of osteochondrosis in foals

OBJECTIVE: To determine whether serum concentrations of biomarkers of skeletal metabolism can, in conjunction with radiographic evaluation, indicate severity of osteochondrosis in developing horses. ANIMALS: 43 Dutch Warmblood foals with varying severity of osteochondrosis. PROCEDURE: 24 foals were monitored for 5 months and 19 foals were monitored for 11 months. Monthly radiographs of femoropatellar-femorotibial and tibio-tarsal joints were graded for osteochondral abnormalities. Serial blood samples were assayed for 8 cartilage and bone biomarkers. At the end of the monitoring period, foals were examined for macroscopic osteochondrosis lesions. RESULTS: Temporal relationships were evident between certain serum biomarkers and osteochondrosis severity in foals during their first year. Biomarkers of collagen degradation (collagenase-generated neoepitopes of type-II collagen fragments, type-I and -II collagen fragments [COL2-3/4C(short)], and cross-linked telopeptide fragments of type-I collagen) and bone mineralization (osteocalcin) were positive indicators of osteochondrosis severity at 5 months of age. In foals with lesions at 11 months of age, osteochondrosis severity correlated negatively with COL2-3/4C(short) and osteocalcin and positively with C-propeptide of type-II procollagen (CPII), a collagen synthesis marker. Radiographic grading of osteochondrosis lesions significantly correlated with macroscopic osteochondrosis severity score at both ages and was strongest when combined with osteocalcin at 5 months and CPII at 11 months. CONCLUSIONS AND CLINICAL RELEVANCE: The ability of serum biomarkers to indicate osteochondrosis severity appears to depend on stage of disease and is strengthened with radiography. In older foals with more permanent lesions, osteochondrosis severity is significantly related to biomarker concentrations of decreased bone formation and increased cartilage synthesis.     

Horse infection with intestinal helminths in relation to age, sex, access to grass and farm system

A 11-year survey on helminth intestinal infection of horses was done in seven provinces of southern Poland. 21,641 faecal samples were collected from horses of different age, sex, breed and management system originating from 84 farms. Age was the major factor influencing the cyathostome egg excretion, the maximum being observed in yearlings and second year horses. Parascaris was found mostly in foals and yearlings. The main factor for Anoplocephala was the access to pasture. The level of cyathostome egg shedding (EPG) could be related to sex (geldings had higher values of EPG), breed (Thoroughbred had higher EPG than other breeds), and type of farm (large farms had higher EPG than others). The change during the survey of anthelmintic treatment (from benzimidazole or pyrantel embonate to avermectins) was associated with lower cyathostome EPG, and this was probably due to partial resistance to benzimidazole. The seasonality of egg shedding (lowest from November to January included) was due to management (leaving the pasture to stable, anthelmintic treatment in October). The influence of climate on EPG was significant but small, annual rainfalls and average temperature being associated negatively and positively, respectively, with high cyathostome EPG.     

Influence of foreign stallions on the Swedish Warmblood breed and its genetic evaluation

The objective of this study was threefold: 1) To survey the use and impact of foreign stallions in the Swedish Warmblood (SWB) breed 2) To investigate the impact of including genetic groups in the genetic evaluation of the SWB and 3) To estimate the impact of incomplete pedigree information on the estimated breeding values (EBVs) for stallions. Data consisted of 189,330 horses of which 50,907 had performance information. Studbook of origin was determined for stallions with at least 5 progeny tested in Sweden. Those 757 stallions had together 116,505 progeny registered in the SWB. Genetic groups were formed according to preliminary analyses of the genetic levels in dressage and show jumping of the different populations. During the first studied period, comprising horses born before 1980, about 80% of the foals were sired by Swedish born stallions, whereas these only sired 40% of the horses born 1990–2003. In this period Holstein stallions had sired 21% of the foals and Dutch stallions (KWPN) 10%. The proportion of mares covered by foreign stallions increased after the early 1980s to about 80% in 2006. Some of the foreign populations, e.g., Holstein, Selle Francais and KWPN, have significantly affected the show jumping performance level of the SWB breed in the past although the deviation from SWB stallions has become smaller over time. Regarding dressage, no particular foreign population has consistently shown such an impact on the performance although Oldenburg stallions seem to be influential lately. The pedigree completeness (PEC values) of the horses included amounted on average to 0.845 for horses with performance data and to 0.907 for stallions with at least 15 progeny. Foreign stallions had an average PEC value of 0.858. When simulating no pedigree information available for foreign stallions, the EBVs of these stallions changed on average by 19–22 index units, which equals about one genetic standard deviation. Thus, keeping complete and correct pedigree registers is crucial for the assessment of reliable EBVs of SWB horses. Including genetic groups in the genetic evaluation of the SWB resulted in hardly any re-ranking of horses. Correlations between EBVs were about 0.99. Inclusion of genetic groups caused larger standard errors of the EBVs. Furthermore, as the pedigrees on average have great depth, and partially also because Warmblood sport horses have become a mix of many different populations, it was not recommended to include genetic groups in the model for future routine genetic evaluations of SWB.