Factors influencing the development of stereotypic and redirected behaviours in young horses: findings of a four year prospective epidemiological study

Stereotypies are invariant and repetitive behaviour patterns that seemingly have no function, which tend to develop in captive animals faced with insoluble problems and may be indicative of reduced welfare. A 4 year prospective study of the factors influencing the development of stereotypic and redirected behaviours (abnormal behaviour) in a population of 225 young Thoroughbred and part-Thoroughbred horses was conducted between 1995 and 1999. Abnormal behaviour affected 34.7% of the population. Multivariable analysis showed that foals of low- or middle-ranking mares were less likely to develop abnormal behaviour than foals of dominant mares (rate ratio (RR) 0.23, P<0.01; RR 0.48, P<0.01, respectively). Weaning by confinement in a stable or barn was associated with an increased rate of development of abnormal behaviour, compared with paddock-weaning (RR 2.19, P<0.05), and housing in barns, rather than at grass after weaning, was associated with a further increase (RR 2.54, P<0.01). Specific stereotypic and redirected behaviours were then considered as separate outcomes. Crib-biting was initiated by 10.5% of horses at median age 20 weeks, weaving by 4.6% of horses at median age 60 weeks, box-walking by 2.3% of horses at median age 64 weeks and wood-chewing by 30.3% of horses at median age 30 weeks. Wood-chewing developed at a lower rate in horses born to subordinate or mid-ranking mares than in horses born to dominant mares (RR 0.29, P<0.01; RR 0.41, P<0.01, respectively), and at a higher rate in horses kept in barns or stables rather than at grass after weaning (RR 4.49, P<0.001; RR 1A6, P<0.001, respectively). Feeding concentrates after weaning was associated with a 4-fold increase in the rate of development of crib-biting (RR 4.12, P = 0.02). The results of this study support the idea that simple changes in feeding, housing and weaning practices could substantially lower the incidence of abnormal behaviour in young horses.     

BLOOD GLUTATHIONE PEROXIDASE ACTIVITY IN HORSES IN RELATION TO MUSCULAR DYSTROPHY AND SELENIUM NUTRITION

The activity of glutathione peroxidase, a selenium containing enzyme, was measured in the blood of horses to determine its usefulness as an indicator of selenium status. In 15 horses the enzyme activity was positively related to the blood selenium concentration (P<.001, r - 0.98) over the range of enzyme activities of 8.2 to 140 units (μmoles NADP-oxidised/min/gHb) and selenium concentrations of 0.24 to 2.74 μmol/k1. In a group of 8 horses which 2 foals had died with lesions of muscular dystrophy the enzyme activity increased from a mean of 11.8 units before treatment with selenium to 34.5 units after 2 intravenous injections of sodium selenite given one month apart. Another group of 8 horses grazing paddocks adjacent to this affected group did not receive any selenium treatment and had a mean enzyme activity of 11.9 units. Blood glutathione peroxidase activity was measured in 50 pasture-fed horses and 180 stallfed horses. The range of activities found (7 to 158 units) indicated that selenium intake in horses varied widely between localities. All pasture-fed horses grazing areas where muscular dystrophy had occurred in foals had low activities (less than 20 units). In stall-fed horses the enzyme activity was influenced by selenium treatment, and horses which had been treated usually had higher activities than horses in the same stable with no history of selenium treatment. It was concluded that blood glutathione peroxidase is a suitable indicator of selenium status in horses.     

Studies on serum tocopherol, selenium levels and blood glutathione peroxidase activities in calves with white muscle disease

For the purpose of clarifying the cause of white muscle disease (WMD) in calves, tocopherol and selenium levels and blood glutathione peroxidase (GSH-Px) activity were measured on 10 calves with WMD and nine of their dams. The main clinical symptoms of the 10 calves with WMD were motor disturbances including recumbency and stiffness. Serum enzyme activities (GOT, GPT, CPK, LDH) in calves with WMD increased markedly, and this increase was also observed in some of their dams. Serum tocopherol levels of calves with WMD were low, 70% of which showing deficient levels of less than 70 micrograms/100 ml. Serum selenium levels of all the calves were lower than 35 ppb, indicating a deficiency, and were accompanied by low blood GSH-Px activity. alpha-Tocopherol and selenium concentrations in organs were very low. Dams of calves with WMD showed low serum tocopherol levels, 22% of which indicating deficient levels below 150 micrograms/100 ml. Serum selenium levels in dams showed a marked decrease to under 20 ppb, and also low blood GSH-Px activity. Feedstuffs supplied in the farms to affected calves indicated very low alpha-tocopherol contents (below 3 mg/100g DM) and low selenium concentrations below 50 ppb in DM. It was concluded that WMD in calves was attributable to nutritional muscular dystrophy caused by deficiencies in tocopherol and selenium in feedstuffs supplied to their dams.     

Effects of vitamin E and selenium administration on pregnant,heavy draft mares on placental retention time and reproductive performance and on white muscle disease in their foals

This study investigated the effects of administering vitamin E and selenium to pregnant heavy draft horsemares on the incidence of retained placenta and postpartum reproductive performance and on the prevention of the white muscle disease in their foals. In study A, 1,000 mg of vitamin E and 50 mg of selenium (E-SE 20 mL) were given to 22 mares 3 weeks before expected parturition (335 days counted from last mating), whereas 28 mares were used as controls. In study B, E-SE were administered 2 weeks before expected parturition at 2 dose levels, with 25 mares receiving 20 mL E-SE, 19 mares receiving 10 mL, and 29 mares kept as controls. Vitamin E and selenium were assayed in serum collected from some of the mares before administration of E-SE and again postpartum and from the foals immediately after birth. Serum selenium concentrations before E-SE administration were deficient (<65 ng/mL) in all mares (n = 48) but were increased in the postpartum sample from treated mares regardless of the dose or timing of administration (n = 31) (P = .05). Only study B mares were deficient in vitamin E prepartum, and both dose levels of E-SE had corrected this in the postpartum sample (P = .01). All foals were selenium deficient regardless of whether their dams had received E-SE or not, although concentrations were higher in foals from treated study A mares than from controls (P = .05). Mares with the highest selenium concentrations prepartum (40 ng/mL and over) had shorter placental retention times than mares with lower selenium concentrations (P = .05) and did not respond to E-SE with a further reduction in retention time. By contrast, mares with prepartum selenium concentrations between 20 and 40 ng/mL tended to respond to E-SE with a shortened placental retention time (P = .07). E-SE administration reduced the mean number of days from parturition to last mating (nonpregnant term) in study B mares (P = .05) and in mares with adequate prepartum vitamin E concentrations (>300 g/mL, P = .05). We conclude that maintaining high level serum vitamin E and selenium concentrations of prepartum mares is expected to increase fertility of selenium-deficient mares. Therefore, the regimen of vitamin E and selenium administrations to selenium deficient mares should be developed.     

Studies on serum tocopherol and selenium levels and blood glutathione peroxidase activities in lambs with white muscle disease

For the investigation of the cause of white muscle disease (WMD), tocopherol (Toc) and selenium (Se) levels and blood glutathione peroxidase (GSH-Px) activities were examined using lambs with WMD and their ewes. Serum Se levels of 4 lambs with WMD were low under 30 ppb, lambs showing very low levels below 15 ppb. The serum Se level was correlated with blood GSH-Px activity showing remarkably low activities in the lambs with WMD. Se contents in the organs of lambs with WMD were lower than those of control lambs, and particularly liver Se contents were deficient levels below 50 ppb. Serum Toc levels were normal, but alpha-Toc contents in organs showed very low levels, especially in the liver. The serum Toc and Se levels and blood GSH-Px activities of their ewes and other sheep kept in the same farm revealed similar results to those of lambs with WMD. Feedstuffs supplied on the farm showed the deficient level of the Se content below 50 ppb and a very low level of alpha-Toc. It was concluded that WMD of lambs in Hokkaido was nutritional muscular dystrophy resulted from deficiencies of Toc and Se to their ewes.     

Serological responses of mares and weanlings following vaccination with an inactivated whole virus equine herpesvirus 1 and equine herpesvirus 4 vaccine

Equine herpesvirus 1 (EHV-1) is a major cause of respiratory disease and abortion in horses worldwide. Although some vaccines have been shown experimentally to reduce disease, there are few reports of the responses to vaccination in the field. This study measured antibody responses to vaccination of 159 mares (aged 4-17 years) and 101 foals (aged 3-6 months) on a large stud farm with a killed whole virus EHV-1/4 vaccine used as per the manufacturer's recommendations. Using an EHV glycoprotein D (gD)-specific ELISA and a type-specific glycoprotein G (gG) ELISA, respectively 13.8 and 28.9% of mares, and 42.6 and 46.6% of foals were classed as responding to vaccination. Additionally, 16.4 and 17.6% of mares were classified as persistently seropositive mares. Using both assays, responder mares and foals had lower week 0 mean ELISA absorbances than non-responder mares and foals. Responder mares were ten times more likely to have responder foals, and non-responder mares were six times more likely to have non-responder foals than other mares using the gG ELISA. Mares aged 7 years or less and foals aged 4 months or more were more likely to respond to vaccination than animals in other age groups. There was no association between response of mares and the number of previous vaccinations received and persistently seropositive mares did not respond to vaccination. This study documents the responses of mares and foals to vaccination in a large scale commercial environment in 2000, and suggests that knowledge of antibody status may allow a more selective vaccination strategy, representing considerable savings to industry.     

断奶前马驹与母马粪便菌群多样性分析

试验旨在探究断奶前马驹和母马粪便菌群多样性,为丰富此阶段马驹肠道菌群多样性提供依据。选取5匹5岁（2胎）、平均体重（453.34±54.23）kg、健康的纯血马母马,以及母马所生的5匹马驹,出生日期相近（±5 d）,平均体重（185.65±9.54）kg,3公2母。母马和马驹在相同环境下饲养,母马日粮组成及营养水平相同,马驹除哺乳外采食的粗饲料和精料补充料相同。马驹6月龄断奶,在断奶前1周用灭菌收粪袋采集母马和马驹的粪便样品。结果显示,母马粪便中菌群α多样性Chao1和ACE指数显著高于马驹（P < 0.05）,分别比马驹高18.94%和15.62%;母马与马驹共有的菌种数为1 399个,母马与马驹特有的菌种数分别为150和68个;在门水平,母马与马驹粪便中排在前十的菌分别是厚壁菌门、变形菌门、拟杆菌门、放线菌门、广古菌门、疣微菌门、螺旋体菌门、Unidentified_Bacteria、纤维杆菌门和无壁菌门,母马粪便中厚壁菌门丰度显著高于马驹（P < 0.05）;拟杆菌门母马比马驹高33.93%,差异不显著（P > 0.05）。由此可见,母马粪便菌群多样性显著高于断奶前马驹;母马与断奶前马驹粪便主要菌是厚壁菌门、拟杆菌门和变形菌门,母马粪便中厚壁菌门和拟杆菌门丰度均高于断奶前马驹。     

The influence of age and gender on haematological parameters in Lipizzan horses

Haematological parameters [red blood cell count (RBC), white blood cell count (WBC), packed cell volume (PCV), haemoglobin concentration, mean cell volume (MCV), mean cell haemoglobin (MCH) and mean cell haemoglobin concentration (MCHC)] in resting Lipizzan horses were determined for 143 stallions, 104 mares and 25 foals. The mean RBC and WBC values in Lipizzans were in the lower part of the normal range for warm-blooded horses. The mean PCV, MCV and MCH values were higher, but the mean haemoglobin concentration and MCHC values were lower than reported for other warm-blooded horses. In foals, the mean RBC, WBC, PCV, haemoglobin concentration and MCHC values were higher, whereas MCV and MCH were lower than in older animals. Results indicating a significant decrease in WBC (P < 0.01) and an increase in MCV, MCH and MCHC (P < 0.05) with increasing age are consistent with some other reports on warm-blooded horses. The age-related variations in RBC and PCV were less marked. Contrary to some reports, RBC (P < 0.01), WBC and haemoglobin concentration (P < 0.001) were higher in Lipizzan stallions than in mares, but differences in MCHC, MCH and MCV were insignificant. The specific haematological values determined in Lipizzans are presumably a result of selection and should be taken into consideration when dealing with this race of horses.     

A survey of reproductive performance in Thoroughbred mares and morbidity, mortality and athletic potential of their foals

A survey was performed to evaluate the reproductive performance of Thoroughbred mares, estimate risks of dystocia and of morbidity and mortality in foals during the first year post partum and their physical acceptability at age one year. The study population consisted of registered Thoroughbred mares and their foals owned by residents of 4 Western Canadian provinces. Owners were identified using information obtained from the North American Jockey Club, and questionnaires were mailed regarding mares bred in 1988 and their foals born in 1989. Eighty-three per cent of mares were reported to be pregnant at some stage following breeding, and 80% of pregnant mares subsequently gave birth to live foals. Estimates of morbidity and mortality were greater than previously reported, 25% of foals had health problems and 5% died during the first 2 weeks postpartum. Twenty-seven per cent of foals surviving 2 weeks were reportedly affected by some health problem between age 15 days and one year, and 6% died during this period. The case fatality rates of horses with upper respiratory tract infections and diarrhoea were much lower than case fatality rates for infectious diseases occurring less frequently. The rate of death or euthanasia among horses with musculoskeletal problems was relatively high after age 2 weeks. Foals with health problems up to age 2 weeks, or between age 15 days and one year were 5 to 7 times more likely to be classified as physically unacceptable for athletic use. Angular limb deformity was the health problem most commonly reported in foals receiving unacceptable physical assessments, and assessments of longterm athletic potential were apparently not affected by the occurrence of infectious diseases.     

An unusual case of generalized soft-tissue mineralization in a suckling foal

An atypical case of severe soft-tissue mineralization in a 3-week-old foal from a herd of Andalusian horses is described. The herd clinical history and the laboratory findings were compatible with a diagnosis of secondary hyperparathyroidism due to a mineral imbalance in the diet (low calcium and high phosphorus intake). Mares showed a marked increase in serum parathyroid hormone (PTH) approximately 10 times normal levels. Serum PTH was marginally elevated in foals. Clinical signs (unthriftiness, painful joints, lameness in one or more limbs, and stiff gait) were more pronounced in foals than in mares. Two foals died and necropsy of one of them revealed extensive soft-tissue mineralization of arterial walls and pulmonary parenchyma. Clinical signs in mares and foals resolved by 4 weeks after diet adjustment.     

A comparative analysis of the acoustic structure of separation calls of Mongolian wild horses (Equus ferus przewalskii) and domestic horses (Equus caballus)

In equines, calls given by foals or mothers when they are seeking contact with each other or by stallions seeking contact with other group members could be classified as affiliative or separation calls when a reunion follows the vocalizations. To investigate how domestication can affect the characteristics of vocalizations produced by equines, separation calls produced by Przewalski's (Przw) horses and Mongolian domestic horses (MDH) living in the same habitat were recorded, spectrally analyzed, and compared. Species-specific acoustic differences were found in the separation vocalizations of mares and foals. In particular, the second and third formants of the calls emitted by Przw mothers were significantly higher in frequency than those emitted by Mongolian domestic mothers, whereas the same acoustical variables were significantly lower in Przw foals than Mongolian domestic foals. Second and third formants have a significant effect on discriminating separation calls emitted by mares and foals from these different equine species. With the exception of the duration of the call, no significant species-specific differences in acoustic parameters were observed in separation calls emitted by stallions. Bioacoustic analysis can discriminate 2 different species that can be affected by their environment, evolution, and social organization.     

Immunoglobulin isotypes in sera and nasal mucosal secretions and their neonatal transfer and distribution in horses

OBJECTIVE: To determine concentrations of IgA and IgG subclasses in serum, colostrum, milk, and nasal wash samples of adult horses and foals. ANIMALS: Seven 2-year-old Welsh ponies, 27 adult mixed-breed horses, and 5 Quarter Horse mares and their foals. PROCEDURE: Serum was obtained from ponies and adult horses. Colostrum and milk were obtained from mares and serum and nasal wash samples from their foals immediately after parturition and on days 1, 7, 14, 28, 42, and 63. Nasal wash samples were also obtained from 23 adult horses. Concentrations of immunoglobulins were determined by use of inhibition ELISA. To determine transfer of maternal isotypes to foals, concentrations in colostrum and milk were compared with those in foal serum. Serum half-lives of isotypes in foals were also determined. RESULTS: IgGb was the most abundant isotype in serum and colostrum from adult horses, whereas IgA was the predominant isotype in milk. The major isotype in nasal secretions of adult horses and foals > or = 28 days old was IgA, but IgGa and IgGb were the major isotypes in nasal secretions of foals < or = 14 days old. Serum half lives of IgGa, IgGb, IgG(T), and IgA in foals were 176, 32, 21, and 3.4 days, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: The early immunoglobulin repertoire of neonatal foals comprised IgGa, IgG(T), and IgA; endogenous synthesis of IgGb could not be detected until 63 days after birth. The restricted repertoire of immunoglobulins in foals may influence humoral immune responses to vaccination.     

Monitoring distances travelled by horses using GPS tracking collars

Objective The aims of this work were to (1) develop a low-cost equine movement tracking collar based on readily available components, (2) conduct preliminary studies assessing the effects of both paddock size and internal fence design on the movements of domestic horses, with and without foals at foot, and (3) describe distances moved by mares and their foals. Additional monitoring of free-ranging feral horses was conducted to allow preliminary comparisons with the movement of confined domestic horses. Procedures A lightweight global positioning system (GPS) data logger modified from a personal/vehicle tracker and mounted on a collar was used to monitor the movement of domestic horses in a range of paddock sizes and internal fence designs for 6.5-day periods. Results In the paddocks used (0.8–16 ha), groups of domestic horses exhibited a logarithmic response in mean daily distance travelled as a function of increasing paddock size, tending asymptotically towards approximately 7.5 km/day. The distance moved by newborn foals was similar to their dams, with total distance travelled also dependent on paddock size. Without altering available paddock area, paddock design, with the exception of a spiral design, did not significantly affect mean daily distance travelled. Feral horses (17.9 km/day) travelled substantially greater mean daily distances than domestic horses (7.2 km/day in 16-ha paddock), even when allowing for larger paddock size. Conclusions Horses kept in stables or small yards and paddocks are quite sedentary in comparison with their feral relatives. For a given paddock area, most designs did not significantly affect mean daily distance travelled.     

Passive transfer failure in horses: incidence and causative factors on a breeding farm

A prospective study was performed to determine the incidence and associated maternal and managemental factors of failure of passive transfer (FPT) in foals on a breeding farm. The zinc sulfate turbidity test (ZSTT) and latex agglutination test (LAT) were compared for accuracy in estimating serum immunoglobulin (Ig)G of foals, as determined by single radial immunodiffusion (SRID). Complete past and present foaling histories of 136 Standardbred mares were obtained. All foalings were witnessed by farm attendants, and colostral samples were collected from mares within 2 hours after parturition. Foals that did not rise and nurse were supplemented with colostrum from the dam, using a bottle or nasogastric tube. Serum samples were prepared from foals and mares between 24 and 36 hours after parturition, and from some mares 45 to 90 days before parturition. Serum IgG concentrations of mares and foals and colostral whey were determined, using SRID. Serum IgG also was estimated in foals, using ZSTT and a commercially available LAT. Four of the 136 foals (2.9%) had FPT (serum IgG less than or equal to 400 mg/dl). Serum IgG concentrations in foals significantly correlated with colostral IgG (P less than 0.001). A significantly larger proportion of foals with FPT were bottle-fed their colostrum (P less than 0.01). Month of parturition, mare age, parity, number of barren seasons, incidence of assisted births or retained placenta, or prepartum serum IgG concentrations did not significantly affect colostral IgG concentrations or serum IgG concentrations in foals. As serum IgG concentrations in foals decreased and as colostral IgG concentrations decreased, the proportion of mares that prelactated significantly (P less than 0.01) increased.(ABSTRACT TRUNCATED AT 250 WORDS)     

Induction of parturition in mares: effect on passive transfer of immunity to foals

Parturition was induced in 11 mares, using a synthetic prostaglandin. Eight mares, not treated, were used as controls. There was no significant difference between the serum immunoglobulin G (IgG) concentrations of the treated and control mares. The concentration of IgG in the colostrum of treated mares compared favorably with that reported for naturally foaling mares. Four foals from treated mares died or were euthanatized because of weakness during the 1st 24 hours after birth. The mean IgG concentration in the surviving foals from treated mares at 24 to 36 hours of age was 1,561 mg/100 ml, which was significantly (P less than 0.01) lower than the mean concentration of 2,731 mg/100 ml in foals from control mares. The mean serum IgG concentration in foals from control mares was significantly (P less than 0.01) greater than that of their dams, whereas the mean serum IgG concentration of the foals from treated mares was significantly (P less than 0.01) lower than that of their dams.     

Serum lactoferrin and immunoglobulin G concentrations in healthy or ill neonatal foals and healthy adult horses

BACKGROUND: Lactoferrin is a colostral glycoprotein with antimicrobial properties. HYPOTHESES: (1) Serum lactoferrin and immunoglobulin G (IgG) concentrations are correlated and increase in healthy foals after ingestion of colostrum; (2) compared to healthy foals, ill foals will have lower lactoferrin concentrations that correlate with their IgG concentration, neutrophil count, the diagnosis of sepsis, and survival; and (3) plasma concentrations of lactoferrin will be less than serum concentrations. ANIMALS: Healthy foals (n = 16), mature horses (n = 10), and ill foals 1-4 days old (n = 111) that were examined for suspected sepsis were used for blood collection. Colostrum was obtained from 10 healthy mares unrelated to the foals. METHODS: Blood was obtained from the healthy foals at birth and 1-3 days of age and from the ill foals at admission. Serum IgG was quantified by single radial immunodiffusion (SRID). Lactoferrin concentrations in colostrum and blood were determined by an enzyme-linked immunosorbant assay. The sepsis score, blood culture results, neutrophil counts, and survival were obtained on ill foals. RESULTS: The mean colostral lactoferrin concentration was 21.7 microg/mL. Compared to values at birth, serum IgG (18+/-2 versus 2,921+/-245 mg/dL, SEM) and lactoferrin (249+/-39 versus 445+/-63 ng/mL, SEM) concentrations were significantly greater in healthy foals 1-3 days old. Serum lactoferrin concentration in 1-3-day-old healthy foals was not different from mature horses or ill foals. IgG and lactoferrin concentrations were significantly correlated only in healthy foals. Serum lactoferrin concentrations were significantly lower in ill neutropenic foals. The serum IgG concentration was significantly lower in ill foals as compared to healthy foals. Only serum IgG was significantly less in ill foals with a positive sepsis score and in nonsurvivors, Plasma lactoferrin concentrations were lower than serum concentrations, although values were significantly correlated. CLINICAL IMPORTANCE: Although both serum IgG and lactoferrin concentrations increase in healthy foals after ingestion of colostrum, only serum IgG is significantly correlated with the sepsis score and outcome.     

Administration of RRR‐α‐tocopherol to pregnant mares stimulates maternal IgG and IgM production in colostrum and enhances vitamin E and IgM status in foals

This study assessed the effect of a vitamin E supplement given to pregnant mares on immunoglobulins (Ig) levels in foals. In addition, the fatty acid (FA) content and composition of the mares’ milk was assessed. Milk α‐tocopherol concentrations were compared between pregnant Danish Warmblood mares (n = 17) given a daily oral supplement of 2500 international units (IU) RRR‐α‐tocopherol in the last 4 weeks of pregnancy and a group of unsupplemented mares (n = 17) receiving 170–320 IU vitamin E daily originating from the feed. Milk α‐tocopherol was higher in supplemented mares (36.7, 12.4 and 9.8 μmol/l respectively) in relation to control mares (13.1, 6.4 and 5.8 μmol/l on days 1, 2 and 3 respectively; p < 0.001). Milk IgG was higher on days 2 and 3 post‐partum (PP) in supplemented mares (1.03 and 0.73 mg/ml respectively) in relation to control mares (0.79 and 0.56 mg/ml respectively; p < 0.05). Milk IgM was higher on days 2 and 3 post‐partum (PP) in supplemented mares (0.19 and 0.17 mg/ml) in relation to control mares (0.13 and 0.11 mg/ml respectively; p < 0.05). Plasma α‐tocopherol in foals was higher from supplemented mares on days 1, 2 and 3 (5.7, 14.8 and 19.2 μmol/l respectively) in relation to foals from control mares (3.6, 6.1 and 7.6 respectively; p < 0.001). Foal plasma IgM was higher from supplemented mares on day 3 (0.50 mg/ml) in relation to foals from control mares (0.32 mg/ml; p < 0.001). The total FA content in milk was highest on day 1 (21.6 g FA/kg milk) in relation to days 2 and 3 (13.6 and 13.5 g FA/kg milk respectively; p < 0.001). In conclusion, a daily oral supplement of 2500 IU RRR‐α‐tocopherol increased α‐tocopherol content in mare milk and foal plasma, IgG and IgM in mare milk and IgM in foal plasma.     

Assessment of copper and zinc status of farm horses and training thoroughbreds in south-east Queensland

The copper and zinc concentrations in the blood of stabled thoroughbred horses and in Australian Stock Horses mares at pasture, either late pregnant or lactating were determined by an atomic absorption spectroscopic method. The plasma concentration of the trace elements in these apparently normal horses were generally below the "normal" range. The plasma copper, caeruloplasmin copper, whole blood copper and plasma zinc concentrations in the stabled thoroughbreds were 0.76 +/- 0.19 micrograms/ml (n = 82), 0.56 +/- 0.14 micrograms/ml (n = 83), 0.75 +/- 0.18 micrograms/ml (n = 82) and 0.47 +/- 0.09 micrograms/ml (n = 83) respectively. The plasma copper and zinc concentrations of all the brood mares at pasture (pregnant and lactating) were 0.56 +/- 0.20 micrograms/ml and 0.47 +/- 0.11 micrograms/ml (n = 30). The plasma copper concentration of the pregnant group of mares (0.64 +/- 0.18 micrograms/ml; (n = 14) was greater than that of the lactating mares (0.49 +/- 0.21; (n = 16). Variation in the plasma copper concentration was also identified between stabled and farm horses, between horses of different stables and between horses of different ages. The proportion of plasma copper bound to caeruloplasmin was 73 +/- 11.8%. These low concentrations of copper and zinc in the plasma of apparently normal horses are of clinical significance since recent evidence has indicated that copper deficiency appears to promote the development of skeletal abnormalities in foals. An alternative to the use of a single plasma sample to identify the copper or zinc deficient horse was discussed.     

Serum vitamin E and blood glutathione peroxidase values of horses with degenerative myeloencephalopathy

Serum vitamin E and blood glutathione peroxidase values were determined in 40 horses with a histologically confirmed diagnosis of degenerative myeloencephalopathy and in 49 age-matched control horses with normal neurologic function. Significant differences were not detected in serum vitamin E or blood glutathione peroxidase values between horses affected with degenerative myeloencephalopathy and control horses. These findings fail to support a reported role of vitamin E deficiency as a cause of equine degenerative myeloencephalopathy.     

Clinical biochemistry of pregnant and nursing mares

BACKGROUND: Pregnancy and lactation result in increased metabolic demands. Although homeostatic mechanisms function to keep substances in blood at relatively constant levels, some changes in the concentrations of routine clinical chemistry analytes are likely to occur. OBJECTIVES: The purpose of this study was to determine what physiological changes occur in serum clinical biochemistry analytes in pregnant and nursing mares, and to determine whether the changes were substantial enough to warrant separate reference intervals for pregnant or lactating horses. METHODS: Forty-two Quarter Horse, Thoroughbred, Saddlebred, Standardbred and Morgan mares were entered into the study while pregnant. They were bled once each month through birth. Studies were continued on 20 mares until their foals were weaned. Test results were tabulated by time before or after birth. Serum biochemistry values were determined by standard methods using automated analyzers. Test results were analyzed using the Kruskal-Wallis 1-way ANOVA on ranks. If a significant difference was found (P<.05), Dunn's multiple comparison procedure was performed on all pairs. Results from pregnant and nursing mares also were compared with a reference group of 19 open, nonlactating mares. RESULTS: Serum triglyceride, potassium, creatinine, and total bilirubin concentrations were lower during lactation than during pregnancy. Serum calcium concentration also was slightly decreased at 2 time points during lactation. Triglyceride concentration was highest during midgestation, while bilirubin and creatinine values increased, and potassium and calcium remained constant during pregnancy. Serum urea concentration also remained constant during pregnancy but increased during lactation. Serum phosphate concentration was lowest during midgestation and highest during lactation. Total CO2 values were highest, and anion gaps were lowest, during midgestation. No significant differences were found in serum albumin, globulin, albumin:globulin ratio, total protein, or glucose values. When compared with the reference group of open mares, serum triglyceride, potassium, bilirubin, and total CO2 concentrations were lower, and anion gap was higher in horses that were nursing. CONCLUSIONS: Although most biochemical values remained relatively constant, significant differences were observed during pregnancy and lactation. Changes in the concentrations of triglycerides, potassium, bilirubin, total CO2, and anion gap during lactation were substantial enough to warrant separate reference intervals for lactating horses.