Traumatic cervical spinal cord injury: a prospective clinical study of laryngeal penetration and aspiration.

STUDY DESIGN: Prospective cohort study. OBJECTIVES: Dysphagia is a relatively common secondary complication in patients with traumatic cervical spinal cord injuries (TCSCI). The purpose of this study was to determine the incidence of aspiration and penetration in patients with acute TCSCI. SETTING: Tampere University Hospital, Tampere, Finland. METHODS: A total of 46 patients with TCSCI were evaluated with a videofluoroscopic swallowing study (VFSS). Rosenbek's penetration-aspiration scale (PAS) was used to classify the degree of penetration or aspiration. The medical records of each patient were systematically reviewed. RESULTS: Of the 46 patients, 85% were male. The mean age at the time of the injury was 62.1 years. Most patients had an incomplete injury (78%), and most of them due to a fall (78%). In the VFSS 19 (41%) patients penetrated and 15 (33%) aspirated. Only 12 (26%) of the patients had a PAS score of 1 indicating that swallowed material did not enter the airway. Of the patients who aspirated, 73% had silent aspiration. CONCLUSION: The incidence of penetration or aspiration according to VFSS is high in this cohort of patients with TCSCI. Therefore, the swallowing function of patients with acute TCSCI should be routinely evaluated before initiating oral feeding. VFSS is highly recommended, particularly to rule out the possibility of silent aspiration and to achieve information on safe nutrition consistency.

Clinical correlates of cerebral diffusion tensor imaging findings in chronic traumatic spinal cord injury.

STUDY DESIGN: Prospective clinical case-control study. OBJECTIVES: The aim of this study was to use diffusion tensor imaging (DTI) to assess the state of cerebral white matter tracts after spinal cord injury (SCI). The DTI metrics were evaluated in relation to neurological deficits and to the size and level of the spinal cord lesions. SETTING: Tampere University Hospital, Tampere, Finland. METHODS: Thirty-four patients (n=34) with clinically complete and incomplete SCI were evaluated using the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI). DTI metrics (fractional anisotropy (FA) and apparent diffusion coefficient (ADC)) were calculated for multiple levels along the course of the corticospinal tract. The state of the spinal cord after injury was assessed using conventional magnetic resonance imaging (MRI). DTI parameters were compared with 40 orthopedically injured control subjects. RESULTS: Statistically significant differences in the DTI values between patients and controls were detected in the posterior area of the centrum semiovale. In this area, the FA values were lower in the patients compared with controls (P=0.008). For patients with clinically complete injury, the difference was even more significant (P=0.0005). Motor and sensory scores of the ISNCSCI correlated positively with FA and negatively with ADC values of the centrum semiovale. A moderate association was observed between the macroscopic changes in the spinal cord and the DTI abnormalities in the centrum semiovale. CONCLUSION: In patients with chronic SCI, DTI changes can be observed in the cerebral white matter. These alterations are associated with the clinical state of the patients.

Centralized spinal cord injury care in Finland: unveiling the hidden incidence of traumatic injuries.

STUDY DESIGN: Population-based prospective study. OBJECTIVES: To determine the incidence and evaluate the characteristics of newly injured patients with traumatic spinal cord injury (TSCI) admitted to two of the three national spinal cord injury (SCI) centers during the first year after the centralization of SCI care in Finland. SETTING: Oulu and Tampere University Hospital SCI centers, Finland. METHODS: The designated rehabilitation teams evaluated all of the patients with a new SCI and persisting neurological symptoms. The data were recorded according to the International Spinal Cord Injury Core Data Set. RESULTS: In a 1-year period, 77 new patients with TSCI were admitted to the study centers serving a population of 3 065 946. In the whole catchment area, the mean annual incidence of TSCI was 25.1 per million, and in the hospital districts of the SCI centers, the incidence was even higher, at 38.1 per million. The mean age of the patients was 58.7 years. Falls were the leading cause of injury (64.9%), and the injury resulted in tetraplegia in 70.1% of the cases. Alcohol use was a contributing factor in 39% of the cases in the entire sample and in 58.6% of cases among patients aged younger than 60 years. CONCLUSION: The incidence rates of TSCI were markedly higher than expected, demonstrating the previously hidden morbidity. The epidemiological features of TSCI appeared to follow the trends in developed countries, highlighting the increasing incidence of cervical lesions due to falling among the elderly. The results need to be confirmed in an extended follow-up.

Mid-term results for three contemporary total knee replacement designs - a comparative study of 104 patients with primary osteoarthritis.

AIMS: The purpose of this study was to compare retrospectively the mid-term clinical and radiological results of three contemporary knee designs in cohorts operated on in the same hospital during the same time period. MATERIALS AND METHODS: We evaluated mid-term clinical and radiographic outcome of three contemporary total knee designs (the AGC V2, the Duracon and the Nexgen) in 104 consecutive patients (129 knees) operate on for primary knee osteoarthritis at our hospital. The mean indexed age at the time of the operation was 69.2 years (range, 49.3 to 81.1 years). The mean follow-up time was 6.0 years (range, 0.2 to 7.9). All patients were followed for at least three years or until the first revision. In the survival analyses, the end point was defined as, revision for any reason. RESULTS: The Kaplan-Meier survival analysis showed a 98% (95% CI 94-100) survival rate for the NexGen, a 98% (95% CI 93-100) for the AGC and a 90% (95% CI 81-99) for the Duracon design at six years. Both the mean KSS for pain, KSS for function and the mean clinical knee score improved significantly in all three groups. There was no difference between the three designs in mid-term survivorship. CONCLUSIONS: Most of the revisions could be directly linked to perioperative surgical errors. In conclusion, the most recently introduced knee replacements of the present study (Duracon and Nexgen) did not show any clinically significant benefit over the older design (AGC) in the mid-term.

Acute BRSV infection in young AI bulls: effect on sperm quality.

Bovine respiratory syncytial virus (BRSV) infection is an important part of the calf pneumonia complex, occasionally affecting even adult cattle. However, the pathogenicity of BRSV in animals older than 6 months is often neglected. Finland is free of many contagious diseases in farm animals, and this gives a good opportunity to study the effects of specific pathogens on bovine reproduction. This report describes the deteriorating effects of BRSV epizootics on sperm morphology and fertility of young dairy bulls (n = 79) at a bull station. More than half of the young bulls had a clinical respiratory disease caused by BRSV during their quarantine when they were 6 months old. Four of seven subsequent quarantine groups were affected. Six months later, when these seropositive bulls (n = 54) came into semen production, they had poorer sperm morphology, and the proportion of normal spermatozoa was 74.1% in BRSV-seropositive animals compared with 81.2% in seronegative bulls (n = 25) (p = 0.035). Field fertility was also slightly affected, the 60-day non-return rates were 75.2% and 76.8% for BRSV seropositive and seronegative bulls respectively (p = 0.014). Potential reasons for lowered sperm quality are discussed here.

Quality of stallion semen obtained by a new semen collection phantom (Equidame) versus a Missouri artificial vagina.

A study was performed to test a new semen collection device (Equidame phantom) that fractionates the ejaculate by comparing the quality of semen obtained by the Equidame phantom with that obtained by a Missouri artificial vagina. Semen from 4 Finnhorse stallions was collected 4 times per stallion by both methods. Half of the ejaculate was frozen and the other half extended and loaded into 2 Equitainer transport containers (24- and 48-h samples). Motility parameters were determined by a Hamilton-Thorn motility analyzer after cooled storage for 24 and 48 h and again after freezing/thawing. Raw and chilled semen samples were cultured and the number of bacterial colonies counted after incubations of 24 and 48 h. After a 24-h incubation the number of colony-forming units (CFU) in raw semen was significantly higher (P<0.01) when collected by the Missouri artificial vagina than by the Equidame phantom. After cooled storage, 75% of the semen samples contained no bacteria after an incubation of 24 h, and 69% yielded no growth after 48 h. The sperm-rich fractions (Cup 2) collected by the Equidame phantom had lower mean volumes (22.1 +/- 2.3 mL [+/- SEM] versus 101.6 +/- 9.3 mL) and significantly higher mean sperm concentrations (218.0 +/- 25.8 x 10(6) vs 86.2 +/- 8.1 x 10(6) cells/mL; P<0.05) than the total ejaculates collected by the Missouri device. The total and progressive motility of chilled and frozen-thawed semen did not differ significantly between collection methods. The Equidame phantom yielded semen that was of a lower bacteriological colony counts, but had sperm motility similar to that of semen collected with the traditional method by the Missouri artificial vagina.

Recovery rate and quality of embryos from mares inseminated after ovulation.

The aim of this study was to evaluate the quality of embryos and their recovery rate from mares inseminated at different intervals after ovulation. Finnhorse and warmblood mares were inseminated with fresh semen 8 to 16 h, 16 to 24 h, or 24 to 32 h after ovulation. Control mares were inseminated before ovulation. Sixty-seven embryo flushings were performed between Days 7 and 9 after ovulation/insemination. Thirteen mares were not flushed, but their uteri were scanned for pregnancy on Days 14 to 16. Embryo recovery rates decreased as time from ovulation to insemination increased, although embryo quality remained normal as evaluated by morphological criteria and mitotic index. However, postovulatory insemination in this trial appeared to delay embryo development, since the embryos recovered from mares inseminated after ovulation were appreciably smaller and at an earlier stage of development than control embryos recovered from mares inseminated prior to ovulation. Part of this delay in embryo development in the postovulation group could be due to the time needed for sperm capacitation. In addition, as the time from ovulation to insemination increased, embryo development might have been further delayed by defects in the aging oocyte.

A novel automated fluorometric assay to evaluate sperm viability and fertility in dairy bulls.

The artificial insemination (AI) industry is in need of an objective and rapid, but inexpensive method to evaluate frozen thawed bull semen ejaculates. This study presents a new fluorescence method that uses an automatized fluorometer and fluorophore stain propidium iodide that stains only those cells with damaged membranes. The fluorescence of the semen sample and the totally killed subsample were measured simultaneously, and viability was calculated. Every semen batch was analyzed before use in AI. For fertility evaluation, the nonreturn rates (NR%) obtained from 92,120 inseminations with the analyzed batches were recorded from 166 bulls (436 batches). This study confirms a 3.9% better NR% for the Finnish Holstein-Friesian breed than for Finnish Ayrshire. There was a clear seasonality in NR%: it differed (5.3%) significantly, being best in summer to autumn (June to October) and lowest in winter (January to March). The fluorometer method was fast and easy. The correlation between the total number of viable spermatozoa in an insemination dose and field fertility was low but significant (r = 0.051, P = 0.016), suggesting that the plasma membrane integrity evaluation can serve as a cost-beneficial quality control method of frozen-thawed semen at bull stations.

Some effects of multiple administration of detomidine during the last trimester of equine pregnancy.

Detomidine was given to 11 pregnant mares at 3 week intervals during the last trimester of pregnancy. Maternal and fetal electrocardiographs were recorded and fetal activity studied by transabdominal ultrasonography, before and 2 h (2, 5, 10, 20, 30, 60, 90 and 120 min) after injection. After parturition, the foals were examined and weighed. Maternal and fetal heart rate showed an initial decline after detomidine administration. Maternal heart rate in the treatment group were lower already 2 min after injection, but a reduction in fetal heart was first seen 5 min after detomidine administration. Mean fetal heart rate at 2 min after detomidine injection was 109, 104, 95 and 90 beats/min, whereas at 5 min it was 80, 76, 72 and 66 beats/min in the 2nd, 3rd, 4th and 5th examination session, respectively. The heart rates did not revert to the control values during follow-up. Decline and recovery patterns were quite similar during all examination sessions. The mares exhibited conductive disturbances 2 min after detomidine administration, but fetal heart rhythm remained regular. Fetal activity was decreased at 5 min but had reverted to control values about 90 min after detomidine administration. Administration of detomidine (0.015 mg/kg) to healthy pregnant mares at 3 week intervals during the last trimester had no measurable detrimental effects on the outcome of pregnancy.

Serum profiles of vitamins A, E and D in mares and foals during different seasons.

Twenty mares and 15 foals of the Finnhorse breed were used to determine serum levels of vitamins A, E and D during different seasons. Monthly serum samples were analyzed from mares for 22 mo and from foals for 13 mo after birth. The horses were kept on pasture from early June until early October and in stables during the winter months. Seasonal differences (P less than .001) were found in serum retinol, retinol to protein ratio, alpha-tocopherol and alpha-tocopherol to cholesterol ratio. Values were lowest from February through May and highest from June through August. Serum levels of retinol and alpha-tocopherol of the foals were much lower (P less than .001) than in mares during the first 4 mo of life. As in the mares, serum levels of retinol and alpha-tocopherol decreased (P less than .001) in winter. At 1 yr of age, serum levels of these vitamins increased rapidly on pasture to values that were close to those found in adult horses. Serum 25-hydroxyvitamin D levels were very low throughout the year. However, a small seasonal variation also was found in 25-hydroxyvitamin D concentrations in the mares. Serum 1,25-dihydroxyvitamin D levels in pregnant mares in winter were similar to those found in lactating mares in summer. These levels also were low compared with those in animals of other species.(ABSTRACT TRUNCATED AT 250 WORDS)

Vitamin A, E and D nutrition in mares and foals during the winter season: effect of feeding two different vitamin-mineral concentrates.

The effects of feeding two different vitamin-mineral concentrates on serum levels of vitamins A, E and D and some growth indicators were examined in 30 pregnant mares and 30 foals. One concentrate contained vitamins A and E and the other did not. Both contained vitamin D3. No differences (P greater than .05) in serum levels of retinol and alpha-tocopherol were observed between the feeding groups in the mares, whereas in the weanlings serum levels of dietary vitamins A and E increased (P less than .01) during late winter and early spring. However, the values did not increase to levels found in summer. Serum 25-hydroxyvitamin D levels were very low (compared with animals of other species) in October, decreased (P less than .05) in winter and increased somewhat during the spring. The decrease in January was more pronounced in horses receiving vitamin concentrates containing less vitamin D. These results are interpreted to indicate that, in Finland, the commonly used amounts of dietary vitamins A and E or their bioavailability in vitamin-mineral concentrates are not sufficient to maintain serum concentrations in winter even close to the levels found in horses on pasture. Vitamin D status of horses is difficult to study due to very low serum levels of 25-hydroxyvitamin D.

Biochemical indicators of bone formation in foals after transfer from pasture to stables for the winter months.

Serum alkaline phosphatase activity and serum concentrations of osteocalcin, free thyroxine, protein, and cholesterol were measured in 14 foals monthly from birth to 1 year of age. A transient decrease (P less than 0.05) in alkaline phosphatase activity and osteocalcin, free thyroxine, and cholesterol concentrations was found in November after transferring the horses from pasture to stables for the winter months. During the 2 subsequent months, serum alkaline phosphatase activity and osteocalcin concentration increased slightly. Protein concentration was highest in late fall and decreased (P less than 0.001) in April and May, suggesting inadequate protein nutrition during the winter months. The data were interpreted to indicate a substantial slowdown of bone formation in foals after transfer from pasture to stables. Factors influencing bone formation may include a decrease in physical activity and in serum free thyroxine concentration.

Serum IgG antibody concentrations against environmental microbes in mares and foals during different seasons and effect of stabling practices.

Over periods of 22 and 14 months, IgG antibody concentrations in serum samples obtained monthly from 14 mares and 19 foals, respectively, were measured by use of ELISA against antigens of the following environmental microbes: Aspergillus umbrosus, Penicillium brevicompactum, Rhodotorula glutinis, Absidia corymbifera, Aspergillus fumigatus, Humicola grisea, Micropolyspora faeni, and Thermoactinomyces vulgaris. The mares and foals were on pasture from early June until early October, then were stabled during the winter season until the following June. In the mares, increased antibody concentrations against most microbes were observed typically in midwinter and late spring when the horses were stabled; antibody concentrations against R glutinis, however, peaked in August. Concentrations differed between the summer and winter seasons and, in most instances, between 2 consecutive years and correlated with amounts of rainfall during the previous harvest season. In the foals, circulating passively acquired antibodies disappeared within 3 to 4 months after birth. During the first year of life, substantially increased autogenous antibody concentrations were observed only against R glutinis. Antibody concentrations against the other microbes increased gradually toward the end of the indoor season. In a group of foals transferred indoors in autumn, 6 weeks later than the other foals, antibody concentrations were lower when measured in December. Results supported the view that, to minimize exposure to microbial spores during the winter season, horses should be kept outdoors as much as possible and attention should be focused on improving the ventilation in stables and the quality of feeds and beddings.

Post-partum ovarian activity in Finnhorse mares with special reference to seasonal effects.

In a previous study, times from parturition to the first ovulation were followed in 55 Finnhorse mares on the basis of milk progesterone determinations. Ninety-six per cent of mares had ovulated by day 20 post-partum. If intervals of more than 19 days are excluded from the data, the time from parturition to 1st ovulation was 117 days. However, in cases of foaling before and after the beginning of June the times were 13.0 days and 8.8 days, respectively (p less than 0.001). Long intervals (over 16 days) occurred mainly before 1st May (in 6 out of 7 cases). In a 2nd study, 25 post-partum Finnhorse mares were examined by rectal palpation and ultrasonic scanning. Five and 7 days post partum, but not 2 days post partum there was a statistically significant difference between ovulatory ovaries and non-ovulatory ovaries regarding size of whole ovary and the largest follicle. Six to 8 days before the first post-partum ovulation, the size of the preovulatory follicle was greater in mares which had foaled before the middle of May (32 mm) than in those which had foaled after the middle of May (20 mm) (p less than 0.05). Within 2 days before ovulation there was no statistical difference between the sizes (43 mm and 42 mm, respectively). The growth rate was therefore slower in cases of early foaling (1.8 mm/day) than in cases of late foaling (3.7 mm/day).

Onset of luteal activity in non-foaling mares during the early breeding season in Finland.

The luteal activity in mares was studied in the Equine Research Station (ERS) and in trotting stables (TS) in South-Finland. The mares were Standardbreeds in the TS and mainly Finnhorses in the ERS. Between January and June blood was collected once a week for serum progesterone determinations. The mares in the ERS were distributed in 1 of 3 groups: three-years old not yet in training (N = 38), brood mares (N = 21) and mares in training (N = 47). A 4th group was the mares in training in the trotting stables (N = 73). Every 5th mare in the ERS and every 4th mare in the trotting stables were cycling already at the beginning of the year. Onset of luteal activity in anoestrous mares was most common in the middle of May. Over 95% of the mares were cycling at the beginning of June. In the ERS 40% of the Finnhorse mares in training were cycling through the winter. The three-years old and the brood mares were all anoestrous during winter. They started to cycle on average before the middle of May. Anoestrous training mares started before the middle of April. Anoestrous Finnhorse mares began to cycle later than warm blooded mares in all of the groups studied. Mares which had foaled the previous year were more often anoestrous during the winter than dry mares. The time of year when cycling began in a particular mare tended to be the same from year to year (p less than 0.01).

Effect of 19-norandrostenololylaurate on serum testosterone concentration, libido, and closure of distal radial growth plate in colts.

The long-term effect of anabolic steroid was investigated in 3 experiments. In experiment I, 500 mg of 19-norandrostenololylaurate was given to 5 colts and a dose of 100 mg to another 5 colts every 3rd week. Six colts served as untreated controls. The animals were 12-16 months old at the start, and 24 months at the end of treatment. In experiment II, a dose of 1 mg/kg was given every 3rd week to 4 colts and 0.3 mg/kg every week to another 4 colts. Six colts served as controls. The colts were treated from 7 months to 12 months of age. In experiment III, 1 mg/kg of steroid was given every 3rd week to 3 foals between 3 and 8 months of age. Three foals were used as controls. Libido and hCG-induced serum testosterone concentrations were studied after the cessation of treatments, up to 3 or 4 years of age. Closure of the right distal radial growth plate was determined between 21 and 36 months of age. Treated colts had lower testosterone levels 4.5 months after cessation of treatment in experiment I (p < 0.001) and experiment II (p < 0.05) when compared with the corresponding control groups. Two years after treatments in experiment I, hCG-induced testosterone levels were higher in treated colts than in untreated controls, but the difference was not statistically significant. The treatments had no effect on libido. The anabolic steroid treatment did not cause premature closure of epiphyseal growth plates in any of the experiments, but closure appeared to be delayed. It was concluded that anabolic steroids have long term effects on reproduction. Their influence on serum testosterone can last for years after cessation of treatment, and they can delay the closure of growth plates which can cause increased susceptibility to cartilage injury during exercise.

Onset of luteal activity in foaling and seasonally anoestrous mares treated with artificial light.

Sixty-four mares (27 foaling, 37 barren or maiden), mainly Finnhorses, were subjected to treatment with 14.5 h of light and 9.5 h of darkness, starting at the beginning of December. The onset of cycling in non-foaling mares was estimated by weekly serum progesterone determinations. All of the non-foaling mares cycled in the middle of March. They started to cycle on average in the middle of February, 11.1 weeks after the beginning of the trial. There were statistically significant differences in relation to breed (Finnhorses started to cycle 2 weeks later than warm blooded, p less than 0.02) and in relation to age (brood mares with mean age 10 years, started to cycle 10 days later than those 3 years old, p less than 0.03). However, there was no statistical significant relation to previous lactation, although lactating mares lactating up to the previous autumn started to cycle 7 days later than dry mares (p less than 0.15). Artificial insemination of 14 mares in the 2nd oestrus of the year, in March, resulted in 12 foalings in the subsequent year (86%). The following winter, all pregnant mares (N = 27) were exposed to the same kind of light treatment, starting on 1st December. The 1st mare foaled at the end of January. The time from foaling to 1st post partum ovulation was significantly longer (17.0 days) in foalings taking place within 10 weeks from the beginning of the light treatment period, than in foalings occurring after more than 10 weeks of lighting (12.1 days) (p less than 0.01).

Serum progesterone levels in mares in winter and during transitional periods.

Weekly blood samples were collected for serum progesterone determination from 68 mares during the period from September 1990 to June 1991. A total of 78% (53/68) of the mares became anoestrous: 88% (15/17) of mares with foals and 75% (38/51) of dry mares (p = 0.323). Six mares of the 15 which continued cycling showed persistent corpus luteum for 77 days on average (range 42-106 days). Anoestrus began between September and February, most frequently in December, and ended in January to June, most frequently in March. Mares with foal at foot became anoestrous in 2 separate groups, in September and in December. Anoestrus ended most frequently in February in foaled mares. The mares with foals differed significantly from the other mares both at onset (p = 0.0084) and end (p = 0.0218) of anoestrus. However, the effect of the stable was also significant at onset (p = 0.0386) and end (p = 0.0170) of anoestrus. Since all mares with foals were kept in one stable and dry mares in 4 different stables, the effect of stable and possible differing lighting conditions cannot be separated from the foal effect. The length of anoestrus was on average 101 days for lactating mares and 95 days for dry mares (p = 0.6691). In foaled mares its length was on average 159 days in mares which had entered anoestrus as early as in September-October and 62 days in mares entering anoestrus in December (p = 0.001). The effects of breed and age were not significant in any of the parameters.

The effect of sour milk as a postmilking teat dip for mastitis prevention in a dairy herd.

In a preliminary in vitro study, the growth of Staphylococcus aureus was totally inhibited during incubation for 24 h at 35 degrees C-37 degrees C in a solution of cooked commercial milk with 1% of uncooked commercial sour milk ("A piimä"). In a subsequent clinical trial, "A piimä" sour milk with 5% glycerol was used as a postmilking teat dip from February to June. Quarterly milk samples were drawn once a month aseptically from 133 cows. Percentages of pathogen positive samples and somatic cell count (SCC) from teats dipped with the sour milk were compared with those dipped with a commercial iodine teat dip and those of undipped controls. During March-June there were fewer isolations of S. aureus (2.09%) and coagulase-negative staphylococci (2.52%) in the sour-milk group than in the control group (3.09% and 4.07%, respectively). In iodine group, there were fewer isolations of S. aureus (0.83%) but more isolations of coagulase-negative staphylococci (5.26%) than in the control group. During the study period, the percentages of bacterial isolates did not differ statistically significantly between treatments, p = 0.291. The percentage of quarters with a SCC over 125,000 at the end of the study was one third lower in the sour-milk group than in the control group (16.67% and 26.23% respectively) but the difference was not statistically significant (p = 0.074). The results indicate that a sour-milk teat-dip preparation can inhibit new intra mammary infections (IMI).

Effect of timing of frozen semen insemination on pregnancy rate in mares.

Thirty-four mares were inseminated with frozen semen from one stallion during 2 oestrous cycles, every 48 h until ovulation took place and within 12 h after ovulation. Semen was frozen using the Colorado method. The insemination dose was from 200 to 400 x 10(6) progressively motile spermatozoa. Ovaries were examined every 12 h to determine time of ovulation. Examination for pregnancy was carried out using ultrasonography, 15 days after ovulation. Thirty-five per cent of mares inseminated < 24 h and 23% of mares inseminated between 24-48 h before ovulation were pregnant (p = 0.388). The pregnancy rate in all mares inseminated before ovulation was 30%. In the mares inseminated within 12 h of ovulation, it was 18% (p = 0.253). Younger mares (aged 4-10 yr) had a higher pregnancy rate (59%) than older mares (aged 11-15 yr) (23%), but the difference was not statistically significant (p = 0.057).