bluuebunny/crossref_metadata_2025 huggingface dataset:
Instant centres of rotation of equine limb joints and their relationship to standard skin marker locations
Authors: LEACH D. H. , DYSON SUE
Published: June 2010

The instant centres of rotation (ICRs) of each limb joint, other than the coxofemoral joint and those of the digits, were calculated for eight clinically sound horses from tracings of radiographs according to the method of Reuleaux (1963).

The majority of ICR positions coincided with the attachment sites of the collateral ligaments. The ICR of the scapulohumeral joint, which does not have collateral ligaments, was caudodistal to the caudal part of the greater tubercle of the humerus. The ICR for the femorotibial joint was located just caudal to the femoral attachment of the collateral ligament.

The location of the ICRs calculated for the two joint carpal joint complex was displaced caudad during extreme flexion of the carpus and differed from those calculated separately for either the antebrachiocarpal joint or the intercarpal joint. Interpretation of these ICR positions was confounded by complex spatial motion changes which occur between the carpal bones.

The sites used for skin marker positions in equine locomotion and conformation research generally agree with the ICR positions, particularly for the humeroradial, tarsocrural, and metacarpo‐ and metatarsophalangeal joints. Traditional marker sites used for the scapulohumeral and femorotibial joints would result in overestimation and underestimation respectively of the caudal joint angles.

Inaccuracy of marker placement, together with movement of skin markers and non‐planar motion during joint angulation, limit accurate biokinematic measurement of limb joint angles during locomotion and conformation analysis.
Arthrodesis of the equine distal tarsal joints by perforated stainless steel cylinders
Authors: ARCHER R. M. , SCHNEIDER R. K. , LINDSAY W. A. , WILSON J. W.
Published: June 2010

Perforated stainless steel cylinders filled with autogenous cancellous bone were implanted in the distal tarsal joints of four horses. Graft cell survival was poor two weeks after surgery in one horse. In two horses, at 10 months there was partial arthrodesis of the joints with incorporation of the implants into the osseous union. The implants were filled with vascularised woven bone. These two horses were sound nine months after surgery. One horse fractured its third tarsal bone and was still positive to a hock flexion test 12 months after surgery.
Detection of early pregnancy in mares by the Rosette Inhibition Test and measurement of serum progesterone
Authors: BRANCO M. D. L. , KUCHEMBUCK M. R. G. , PAPA F. O. , FILHO E. P. CAMPOS
Published: June 2010

Early pregnancy factor (EPF) appears to be a protein complex that depends on pregnancy. It has been detected in the serum of several animal species using the Rosette Inhibition Test. In the present study 30 adult, Mangalarga mares with normal reproductive activity were divided into two groups: an experimental group which were mated and/or inseminated, and an unmated control group. In the experimental group, blood samples were taken on the 7th, 14th and 21st days after ovulation. In the control group, blood samples were collected from seven mares in oestrus and eight in dioestrus. In the control group the Rosette Inhibition Titre (RIT) ranged from 3 to 8 × 103, whereas in the experimental group a RIT higher than 8 × 103 was considered an indication of the presence of EPF. Serum progesterone concentrations on Day 7 were equal to or greater than those measured in the mated mares on Day 14 or Day 21.
Allyl trenbolone and flunixin meglumine treatment of mares with repeated embryonic loss
Authors: DARENIUS KERSTIN , FREDRIKSSON G. , KINDAHL H.
Published: June 2010

Two mares being monitored in a project concerning early foetal death failed to maintain their pregnancies despite improved management. They repeatedly lost their conceptuses so one was treated with allyl trenbolone and the other with flunixin meglumine from Day 10 of gestation. Treatment with allyl trenbolone until Day 70 of gestation maintained pregnancy despite regression of the primary corpus luteum and the resulting low levels of endogenous progesterone in peripheral plasma during one month; secondary corpora lutea developed at the expected time. In the other mare with a history of premature release of prostaglandin F2α, treatment with flunixin meglumine until Day 60 of gestation inhibited prostaglandin F2α synthesis and luteal function was maintained.
Patterns of growth and regression of ovarian follicles during the oestrous cycle and after hemiovariectomy in mares
Authors: SIROIS J. , BALL B. A. , FORTUNE J. E.
Published: June 2010

To increase our understanding of the regulation of ovarian follicular development during the oestrous cycle, 13 mares were used in two experiments. In Experiment 1, the pattern of growth and regression of individual follicles, 15 mm or more in size, was monitored daily during 17 oestrous cycles by real‐time ultrasonography. Each examination was recorded on videotape to ensure accurate monitoring of individual follicles. Results indicated that the development of such follicles occurs in waves, with the most common pattern being one follicular wave per oestrous cycle (12 of 17 cycles). An alternative pattern of two follicular waves per cycle was observed in mares with (n=3) and without (n=2) dioestrous ovulations. The ovulatory follicle appeared earlier in the cycle in mares with one wave than in mares with two waves (Day 6.3 ± 0.9 vs Day 11.0 ± 1.2, respectively; p<0.01). Also, the ovulatory follicle was the largest follicle for a longer period of time in mares with one wave than in mares with two waves per cycle (9.5 ± 0.6 vs 5.8 ± 0.3 days, respectively; p<0.01). Mares with one follicular wave had shorter cycles than those with two waves per cycle (18.2 ± 0.6 vs 21.6 ± 0.5 days, p<0.001). In both cases, the interval between the appearance of the ovulatory follicle and its ovulation was, on average, 10 to 12 days. Overall, a negative correlation was found between the relative size of the ovulatory follicle at the beginning of the follicular phase and the length of the follicular phase (r=‐0.91, p<0.001). To study the control of follicular recruitment, patterns of follicular growth were monitored in nine mares following removal of the ovary bearing the presumptive ovulatory follicle (Experiment 2). Hemiovariectomies were performed between Day 14 of dioestrus and the fourth day of oestrus. Follicular dynamics were characterised by the development of one follicular wave that produced one to three ovulatory follicles in seven of nine mares. The ovulatory follicle reached 15 mm or more 6.3 ± 1.5 days following surgery and the interval from hemiovariectomy to ovulation was 13.7 ± 1.3 days. Two of nine mares hemiovariectomised on Day 14 failed to undergo complete luteolysis after the ovary bearing the ovulatory follicle, but not the corpus luteum, was excised. These mares had not ovulated by 30 days after surgery, although follicular waves producing ovulatory size follicles were observed. This study indicated that the development of ovarian follicles 15 mm or larger in the mare occurs in waves, with a more common pattern of one wave and an alternative pattern of two waves per oestrous cycle.
Differences in protein content of uterine fluid related to duration of progesterone treatment in ovariectomised mares used as embryo recipients
Authors: HINRICHS KATRIN , KENNEY R. M. , SHARP D. C.
Published: June 2010

Ovariectomised, progesterone‐treated mares were used to test the effect of two different durations of progesterone treatment on pregnancy rate after embryo transfer, and to examine the effect of duration of progesterone treatment on the secretion of uterine proteins. Ovariectomised mares were assigned to one of two groups: ‘synchronous’ mares, given progesterone from two days after the date of ovulation of a potential donor mare; or ‘asynchronous’ mares administered progesterone from five to seven days before the predicted date of ovulation of a potential donor mare. The day of ovulation of a given donor mare was designated Day 0. Four procedures were performed using both synchronous and asynchronous mares: no transfer; sham transfer at Day 7; embryo transfer at Day 7 resulting in pregnancy on Day 14; and embryo transfer at Day 7 resulting in no pregnancy at Day 14. Uterine fluid was collected from the recipient mares either at Day 7, or seven days after embryo, or sham, transfer (Day 14). This schedule resulted in uterine fluid being recovered after the mares had been treated with progesterone for three different durations: five days (synchronous recipients flushed at Day 7); 12 to 15 days (synchronous recipients flushed at Day 14 or asynchronous recipients flushed at Day 7); and 19 to 21 days (asynchronous recipients flushed at Day 14). Total concentration of protein in uterine fluid tended (P= 0.08) to increase with the duration of progesterone treatment, and the main effect of procedure also tended (P = 0.06) to affect protein content. Acid phosphatase content of uterine flushings was significantly (p<0.05) affected by duration of progesterone treatment, being ten‐fold higher after 19 to 21 days of treatment than after five days of treatment. Characterisation of proteins in uterine fluid by two‐dimensional polyacrylamide gel electrophoresis did not reveal striking qualitative differences in protein patterns, except for a protein apparent in uterine fluid from the two mares treated with progesterone for five days only (synchronous, no‐transfer group). This protein was not observed at other stages.
Histological aspects of uterine involution in the post parturient, ovariectomised, embryo‐recipient mare: a model for the study of involution
Authors: SERTICH PATRICIA L. , HINRICHS KATRIN , KENNEY R. M.
Published: June 2010

This paper compares uterine involution in intact and ovariectomised embryo recipient mares after foaling. There was no difference in the rate of uterine involution between the two groups and on Day 1 post partum intact and ovariectomised mares both have degenerating microcaruncles in the Stratum compactum. At this time the endometrial glands are tortuous and distended along their entire length. By Day 7 post partum the only remaining evidence of the microcaruncle is an area of condensed stroma containing siderophages and a few other mononuclear cells and covered by an intact epithelium. By Day 10 to 11 the cystic glandular distention has resolved.
An attempt to use progesterone treated XO mares as embryo recipients
Authors: PASHEN R. L. , DOWNIE C. , McCUE P.
Published: June 2010

XO mares were evaluated as potential embryo transfer recipients. In the first part of the study, they were treated with oestrogen and progesterone for 10 and 14 consecutive days. During this course of steriod treatment, their endometria changed in histological appearance from anoestrous to dioestrous and their peripheral plasma progesterone levels rose from below 0.3 ng/ml to above 2 ng/ml. Plasma LH concentrations also rose during the period of oestrogen administration but declined again to baseline when progesterone treatment began. Urinary oestrogen concentrations rose and fell in conjunction with oestrogen treatment. In the second part of the study 16 Day 7 embryos were transferred non‐surgically to seven XO mares given daily injections of progesterone and 12 embryos were transferred to eight ovariectomised mares treated similarly with progesterone. Pregnancies were established in five of the ovariectomised mares but not in any of the XO mares. The possible reasons for the failure to establish pregnancy in the XO mares are discussed.
Results from an embryo transfer programme with Mangalarga mares in Brazil
Authors: FLEURY J. J. , NETO J. B. F. COSTA , ALVARENGA M. A.
Published: June 2010

Sixty Mangalarga mares aged two to 28 years were used as donor mares in an embryo transfer programme. They were inseminated on alternate days during oestrus with fresh extended semen collected from a fertile Mangalarga stallion. Non‐surgical embryo recovery was performed on Day 7, 8 or 9 after ovulation (Day 0), using three consecutive uterine flushes of 500, 250 and 250 ml of Dulbecco's phosphate buffered saline. Embryos were transferred surgically to recipient mares between Days 4 and 9 post ovulation. The overall embryo recovery rate was 52.3 per cent (90/172). The recovery rate from seven mares under three years old was 85.0 per cent (17/20), whereas the rate from 34 mares aged three to 18 years was 64.4 per cent (58/90), and from 19 mares more than 18 years old was only 24.1 per cent (15/62). The overall pregnancy rate for the recipient mares at Day 50 was 78.9 per cent.
Transfer of cryopreserved equine embryos to progestin‐treated ovariectomised mares
Authors: SQUIRES E. L. , SEIDEL G. E. , MCKINNON A. O.
Published: June 2010

Good to excellent quality embryos between 160 and 980 μm in diameter were recovered 6.5 to 7 days after ovulation and washed in Dulbecco's phosphate‐buffered saline plus 10 per cent foetal calf serum (PBS). Embryos were frozen in 0.5 ml French straws and seeded at −6°C. Embryos of 200 μm diameter or less were placed in 10 per cent glycerol in PBS and cooled from −6 to −30°C at 0.3°C/min, then to −33°C at 0.1°C/min. They were then plunged into liquid nitrogen. Embryos larger than 200 μm were frozen either 1) in 10 per cent glycerol plus 8.6 per cent sucrose with cooling at 0.5°C/min from −6 to 25°C followed by plunging, or 2) in 15 per cent glycerol plus 15 per cent sucrose and placed between gel‐containing cold packs in a household freezer at — 25°C for 30 mins followed by plunging. Embryos were thawed for 20 sees in a 37°C water bath or held in air for 20 sees prior to thawing in a 37°C water bath for 20 sees. Glycerol from embryos frozen in the household freezer was removed in steps of 12, 9, 6, 3 and 0 per cent glycerol, all with 10 per cent sucrose, 6 mins/step. Glycerol was removed similarly for other treatments but the first two steps were omitted. Embryos were evaluated morphologically (1 = excellent, 5 = severely degenerate) prior to transfer to the uterus of ovariectomised mares between 24th November and 9th January. Mares were given 0.044 mg/kg bodyweight altrenogest for at least six days. Four pregnancies were established after transferring eight embryos 200 μm or less, demonstrating that progestin‐treated, ovariectomised mares can serve as recipients for frozen embryos during the non‐breeding season. However, only two of 24 larger embryos resulted in pregnancy. No difference was detected in the two methods of cooling, but post‐thaw embryo quality was markedly improved (p<0.01) by holding straws in air for 20 sees prior to placing them in a water bath.
Bisection of equine embryos
Authors: McKINNON A. O. , CARNEVALE E. M. , SQUIRES E. L. , CARNEY N. J. , SEIDEL G. E.
Published: June 2010

Three experiments were designed to evaluate methods of bisecting equine embryos. Viability of demi‐embryos was compared to whole embryosin vitroandin vivo.In Experiment 1, Day 6 embryos were bisected either using a standard micromanipulation technique or a manual split of embryos that were adhered to a petri dish. Viability was assessed by culturein vitro.Bisected embryos in both groups increased in size during culture and developed normally. In general, manual bisection was accomplished with less difficulty and time than the micromanipulation method. Eleven additional embryos were bisected manually and both halves transferred surgically into the same recipient (Experiment 2). More pregnancies were obtained from transfer of twin whole embryos (16/22) compared to bisected, demi‐embryos (5/22). In Experiment 3, 30 embryos were bisected manually; 15 were encapsulated in agar chip. Both halves were transferred non‐surgically to each recipient. Fifteen whole embryos were transferred non‐surgically to recipients as controls. The number of vesicles per original embryo was greater for whole embryos than for demi‐embryos in agar chips.
Iridial hypoplasia (aniridia) accompanied by limbic dermoids and cataracts in a group of related Quarterhorses
Authors: JOYCE J. R. , MARTIN J. E. , STORTS R. W. , SKOW L.
Published: June 2010

The clinical, gross and microscopic ophthalmic lesions of iridial hypoplasia, limbic dermoids and cataracts in a Quarterhorse stallion and a group of its offspring are described. It is proposed that the lesions in the stallion were the result of an independent mutation and that the defects were transmitted to its offspring by an autosomal dominant gene.
Tonometric and tonographic studies in the normal pony eye
Authors: SMITH PATRICIA J. , GUM G. G. , WHITLEY R. D. , SAMUELSON D. A. , BROOKS D. E. , GARCIA‐SANCHEZ G. A.
Published: June 2010

Tonometric and tonographic techniques were evaluated in the normal pony and compared to other species. Applanation tonometry was utilised to calculate the ocular ridigity of the normal equine eye. The mean intraocular pressure for the pony eye was established as 23.5 mm Hg (sd ±4.5). Comparing the non‐anaesthetised and anaesthetised pony eye (xylazine‐ketamine and glycerol guaiacolate) no significant change in intraocular pressure occurred (P<0.49). Mean aqueous outflow facility was 0.88 μl/min/mm Hg (sd ±0.65) which is significantly higher (P<0.01) than the canine and human species. The ocular rigidity values for the pony eye were higher which indicates that the eye is more rigid than either the canine or human eye.
Application of a standardised treadmill exercise test for clinical evaluation of fitness in 10 Thoroughbred racehorses
Authors: SEEHERMAN H. J. , MORRIS ELISABETH A.
Published: June 2010

Clinical exercise stress testing is an important diagnostic tool for evaluating exercise intolerance and degree of fitness in human athletes. The purpose of this paper was to describe the methodology necessary to perform a clinical exercise test and report the results of performance evaluations on 10 Thoroughbred racehorses using this test. The test utilised an open flow gas analysis system for ease of use with untrained horses and a fast time response lactate analyser for rapid data analysis. Exercise test measurements used to evaluate fitness included peak oxygen consumption (mean V̇O2peak = 161.9 ± 12.9 ml/kg/min), peak heart rate (mean HRpeak = 232 ± 10 b/m), peak venous blood lactate concentration (mean LAC peak = 15.2 ± 5.8 mmol/l), peak packed cell volume (mean PCVpeak = 0.64 ± 0.3 l/l) and the maximum number of steps completed (mean STEPmax = 8.7 ± 0.5 steps). The relationship between these exercise test measurements with velocity and time post exercise was also evaluated. Change in serum creatine kinase levels resulting from exercise test were minimal (mean ΔSCK = 72 ± 53 u/l).
Pulmonary artery, aortic and oesophageal pressure changes during high intensity treadmill exercise in the horse: a possible relation to exercise‐induced pulmonary haemorrhage
Authors: ERICKSON B. K. , ERICKSON H. H. , COFFMAN J. R.
Published: June 2010

This study investigated changes in packed cell volume (PCV), pulmonary artery and aortic pressures, and the interaction between oesophageal pressure and pulmonary artery and aortic pressures during strenuous exercise in the horse. It was hypothesised that oesophageal pressure changes summate with pulmonary artery and aortic pressures during exercise and contribute to exercise‐induced pulmonary haemorrhage (EIPH). Acute treadmill exercise (10 m/sec, 3° incline) produced increases in heart rate (HR) from 50 to 202 beats/min; mean pulmonary artery pressure (PAP) from 28 to 80 mmHg; mean aortic pressure (AP) from 108 to 157 mmHg; and PCV from 0.35 to 0.52 litres/litre. EIPH was observed in three of seven horses after treadmill exercise, but no differences in the above variables were observed between the two groups of horses. Electronic subtraction of the oesophageal pressure signal from PAP and AP signals indicated peak transmural pressures of approximately 150 mmHg pulmonary and 175 mmHg aortic pressure. The elevated PAP associated with exercise appeared related more to increased HR and less to PCV (blood viscosity) or AP (bronchial). Both pulmonary artery and aortic peak transmural vascular pressures were substantially influenced by oesophageal pressure changes; peak and mean pulmonary artery and aortic pressures were significantly higher than resting pressures, and may conceivably contribute to EIPH.
Accuracy of formulae for calculating left ventricular volumes of the equine heart
Authors: LORD P. F. , CROFT M. A.
Published: June 2010

Echocardiography may be an accurate method of measuring left ventricular (LV) volumes and mass of the horse's heart. If so, studies of the heart size and hypertrophy would be possible. This study evaluated geometric models of the external and internal LV shapes, to determine which could be applied to echocardiographic measurements. We preserved 30 horses' hearts and measured their dimensions and cross sectional areas. These measurements were entered into seven formulae representing different geometric models of the ventricle and its chamber. We derived a correction factor to estimate the long axis as a fixed proportion of the external diameter, so that volumes could be determined from an M‐mode or a cross sectional echocardiogram. Statistical analysis of the regressions of known volumes against calculated volumes measured by water displacement, demonstrated that the ellipsoid formula using cross sectional areas was very accurate in representing the external shape of the left ventricle (slope = 1.01 r2 = 96.3) and its chamber (slope = 0.83, r2 = 94.3). Myocardial volume, measured by subtracting internal (chamber) volume from external volume, was also calculated accurately (slope = 1.01, r2 = 96.5). The ellipsoid formula using directly measured diameter was only slightly less accurate. LV mass could be calculated by applying the specific gravity of equine myocardium, 1.05, to the myocardial volume. Formulae recommended for evaluating are, with M‐mode echocardiography:

and with 2D echocardiography

where De is the external diameter, Di is the internal diameter, Ae the external area and Ai the internal area.
Effects of treadmill elevation on heart rate, blood lactate concentration and packed cell volume during graded submaximal exercise in ponies
Authors: SEXTON W. L. , ERICKSON H. H.
Published: June 2010

Six ponies performed a standardised exercise test on a motorised treadmill at each of three randomly assigned treadmill elevations (1, 4, or 7°). The exercise test consisted of four, 4 min increments of increasing treadmill speed from 1.0 to 3.4 m/sec. Heart rate, blood lactate concentration, and packed cell volume (PCV) were determined, during the last min of each exercise level, and at 4 and 12 mins post exercise. Regardless of treadmill elevation, no differences were observed in pre‐exercise heart rate (49 ± 2) beats/min), lactate (1.2 ± 0.1 mM), and PCV (0.32 ± 0.01 litres. During exercise, heart rate and PCV were highly correlated to treadmill speed and elevation. Peak exercise heart rates (determined at 3.4 m/sec) were 159 ± 10, 182 ± 5, and 216 ± 6 beats/min at 1, 4, and 7°, respectively, while peak PCVs were 0.37 ± 0.01, 0.40 ± 0.01 and 0.42 ± 0.02 lit/litre at 1, 4, and 7°, respectively. Blood lactate did not change significantly from pre‐exercise levels during the exercise test at a treadmill elevation equal to 1°, but increased markedly at 4 and 7°. Peak lactates were 1.9 ± 0.7, 5.3 ± 1.0, and 18.1 ± 1.5 mM at 1, 4, and 7°, respectively. There was a highly significant correlation between heart rate and lactate at all treadmill speeds and elevations. Therefore, during graded, submaximal exercise increasing treadmill elevation up to 7° results in increases in heart rate, blood lactate concentration and PCV comparable to those seen with increasing treadmill speed alone.
The effect of an acute hoof wall angulation on the stride kinematics of trotting horses
Authors: CLAYTON HILARY M.
Published: June 2010

High speed cinematography was used to describe the stride kinematics in a group of six, sound horses subjected to two farriery treatments, designated ‘normal’ and ‘acute’ hoof angulation. Normal was defined as having the dorsal hoof wall aligned with the pastern axis, whereas the acute hoof angulation was approximately 10° lower than the normal angle for the individual horse. The acute angle was achieved by allowing the toes to grow relatively longer than the heels. The results of a multivariate analysis of variance showed significant differences between the two farriery treatments in the mode of hoof impact with the ground and the duration of breakover. The acute angulation was associated with fewer heel‐first impacts and a greater number of toe‐first impacts than the normal angulation (P<0.01). Breakover time was prolonged with the acute angulation (P<0.01). There were no significant differences between the two farriery treatments in stride length, duration of the suspension phase of the stride or duration of the stance phases of the fore or hind limbs (P>0.05). The flight arc of the toe was similar for the normal and acute hoof angles, reaching its highest point shortly after lift off, after which the toe followed a low flight path. There was an elevation of the toe in preparation for heel‐first or flat‐foot impact, but when impact was toe‐first the trace approached the ground smoothly at a more acute angle.
The role of the reciprocal apparatus in the hind limb of the horse investigated by a modified CODA‐3 opto‐electronic kinematic analysis system
Authors: VAN WEEREN P. R. , VAN DEN BOGERT A. J. , BARNEVELD A. , HARTMAN W. , KERSJES A. W.
Published: June 2010

The function of the reciprocal apparatus in the hind limb of the horse was studied by kinematic gait analysis. For recording purposes a modified opto‐electronic CODA‐3 kinematic analysis system was used. The raw kinematic data were corrected for skin displacement artifacts by use of recently developed correction models. It was concluded that contradictory findings about the coupling of tarsal and stifle joints by the reciprocal apparatus, when comparing in vitro and in vivo studies, can be fully attributed to artifacts due to the movement of the skin markers over the underlying bony structures, occurring in the in vivo experiments.
A quantitative analysis of skin displacement in the trotting horse
Authors: VAN WEEREN P. R. , VAN DEN BOGERT A. J. , BARNEVELD A.
Published: June 2010

Skin displacement was investigated at 16 sites in the front and hind limbs of four Dutch Warmblood horses at the trot. For visualisation of the bone under the skin, a measuring device mounted on a Steinmann pin driven into the bone under investigation, was employed. Mean displacements ranged from 8 mm (X‐displacements proximal and distal metacarpus) to 142 mm (Y‐displacement caudal part of greater trochanter). When compared with previously determined skin displacement patterns at walk, mean displacements at trot were of the same magnitude whereas the shape of the time‐displacement curve was different. The latter may be attributed to differences in relative duration of stance and swing phases between the walk and the trot.
Failure of passive immunisation by colostrum from immunised mares to protect foals against Rhodococcus equi pneumonia
Authors: Martens R. J. , Martens Judy G. , Fiske R. A.
Published: June 2010

The immunoprophylactic capacity of colostrum‐derivedRhodococcus equiantibodies was evaluated in pony foals experimentally infected withR. equi.Six pony mares (Group 1) were injected serially with liveR. equiduring pregnancy; a further six pony mares were not vaccinated and used as controls All (Group 2) foals were permitted to suck from their dams and the adequacy of IgG, passively transferred via colostrum, was determined by single radial immunodiffusion. The presence and relative value of R. equi specific antibodies were determined by ELISA. Mares vaccinated withR. equideveloped significantly (P<0.05) increasedR. equiantibody levels, and the principal foals from these mares had specific antibody values that were significantly (P<0.01) higher than control foals.Rhodococcus equiwere aerosolised into a caudal lung lobe of all foals at seven days of age. Clinical signs, haematological alterations, immune responses and thoracic radiographs were monitored. Foals were subjected to euthanasia and complete post mortem examinations were performed. All foals developed pneumonia as evidenced by clinical and radiographic signs. The survival rate for Group 1 foals did not differ significantly from that of control foals. Two of the six foals in each group survived the bacterial challenge. Also, there were no significant differences between groups for duration of survival, peak febrile responses, duration of fever, time from infection to onset of fever, or peak concentrations of leucocytes and neutrophils. Post mortem examinations of four foals from each group, destroyed approximately three weeks post infection because of terminal disease, revealed severe pyogranulomatous pneumonia involving primarily the caudal portion of one lung. One control foal had miliary pyogranulomatous lesions in both lungs.Rhodococcus equiwas cultured from the pulmonary lesions in these foals. Two principal and two control foals that recovered from the infections had mild pulmonary fibrosis at three months post infection.Rhodococcus equiwas not cultured from any of these foals at necropsy. The results of this investigation suggest that passive immunisation of newborn foals, by ingestion of colostrum derivedR. equispecific antibodies, does not provide adequate protection against experimental infection withR. equi.
Therapeutic effects of immune plasma in foals with Rhodococcus equi pneumonia
Authors: Chaffin M. K. , Martens R. J. , Martens Judy G. , Fiske R. A.
Published: June 2010

The immunotherapeutic efficacy of specific immune plasma was evaluated in pony foals infected experimentally withRhodococcus equi. ViableR. equiwere aerosolised into the right caudodorsal lung of 10 foals at seven days of age. Immune plasma, produced by repeated parenteral administration of viableR. equito an adult donor gelding, was harvested and frozen. Group 1 (4 foals) and Group 2 (6 foals) foals received lactated Ringer's solution and immune plasma, respectively, at seven and nine days post infection. Clinical signs, haematological alterations, immune responses and thoracic radiographs were monitored throughout the study. All foals were destroyed and complete post mortem examinations were performed. All foals developed pneumonia as evidenced by clinical and radiographic alterations. Immune plasma had no significant effect on survival rate, length of survival, temperature response or peripheral blood concentrations of leucocytes, neutrophils or fibrinogen. Enzyme‐linked immunosorbent assay values forR. equi‐specific antibody and serum concentrations of IgG were significantly greater in Group 2 foals following treatment with immune plasma. Post mortem examination of three Group 1 and four Group 2 foals, destroyed because of terminal disease, revealed severe pyogranulomatous pneumonia. The two surviving Group 2 foals were free of gross pulmonary lesions and had minimal microscopic scar formation three months post infection; whereas the one surviving Group 1 foal had a large, encapsulated, caseonecrotic pulmonary mass three months post infection. This study demonstrates that the parenteral administration ofR. equiimmune plasma to foals seven days after experimental infection withR. equidoes not alleviate the clinical signs nor alter the course of disease.
Haematological changes and equine lymphocyte subpopulation kinetics during primary infection and attempted re‐infection of specific pathogen free foals with EHV‐1
Authors: Lunn D. P. , Holmes M. A. , Gibson J. , Field H. J. , Kydd Julia H. , Duffus W. P. H.
Published: June 2010

Four specific pathogen‐ (Equid Herpesvirus type 1 [EHV‐1]) free foals aged 2 to 3 months were intranasally inoculated with 7 times 107p.f.u. of EHV‐1. Virus isolation was attempted from peripheral blood and nasal mucus, and clinical signs of disease and haematological changes were monitored. Also, lymphocyte subpopulations were enumerated using flow cytometric analysis of lymphocytes identified using a polyclonal anti‐equine immunoglobulin reagent and monoclonal antibodies recognising the equine homologues of CD4, CD5 and CD8. The primary intranasal inoculation of virus resulted in an EHV‐1 infection demonstrated by viraemia, persistent nasal shedding of virus, seroconversion and clinical signs of disease. Associated with this infection there was a fall in lymphocyte and neutrophil counts, which subsequently rose to normal levels with alleviation of the clinical signs of disease. The decline in lymphocyte count resulted from a fall in T‐lymphocyte numbers only, and the subsequent increase was initially also a T‐lymphocyte‐restricted event with a later increase in the number of B lymphocytes. The fall in T lymphocyte count affected the CD4+ and CD8+ subpopulations equally; however, during the subsequent rise there was a proportionately greater increase in the CD8+ subpopulation. Following recovery from the primary infection, the foals were re‐challenged with a repeat inoculation two months after the primary infection. This second inoculation did not result in clinical disease, detectable viraemia, increased antibody titres or persistent nasal shedding of virus, suggesting an effective immune response or subclinical infection. The marked patterns of leucocyte and lymphocyte subsets of the primary infection were not evident; however, there was a definite decline in the numbers of CD8+ lymphocytes that lasted for several days. The implications of these findings are discussed.
Evidence for non‐specific immunosuppression during the development of immune responses to Equid Herpesvirus‐1
Authors: Hannant D. , O'Neill T. , Jessett D. M. , Mumford Jennifer A.
Published: June 2010

Six ponies were experimentally infected with an isolate of Equid Herpesvirus type 1 (EHV‐I) recovered from an aborted foetus. Clinical, virological and serological observations confirmed that infection was established in all ponies. EHV‐I specific cellular immune responses as measured by T cell proliferation developed in parallel with specific antibody. In contrast to this, non‐specific lymphocyte function was shown to be compromised after infection in that polyclonal T cell activation was depressed for at least 40 days. The dissociation of specific and non‐specific cellular immune responses suggests that an immunological defect may develop in horses after EHV‐I infection. The mechanism for this immunosuppression is not understood but it is unlikely to reflect a reduction in responding lymphocyte numbersin vivobecause the observed immunosuppression continued well beyond the period of transient leucopaenia commonly seen with EHV‐1.
Insulin and glucose response following oral glucose administration in well‐conditioned ponies
Authors: FREESTONE J. F. , SHOEMAKER K. , BESSIN R. , WOLFSHEIMER K. J.
Published: June 2010

Twenty‐three well‐conditioned ponies were evaluated for insulin and glucose response following oral glucose administration (1 g/kg bodyweight [bwt] as a 20 per cent solution). Ponies were defined as normal if total insulin secretion (TIS) was less than 149 μiu/ml h and the glucose concentration was below 11.1 ± 0.11 mmol/litre (200 ± 2 mg/dl) at all times following oral glucose administration. When glucose concentrations were maintained below 11.1 ± 0.11 mmol/litre, the area under the glucose curve (TG) was less than 17.4 mmol/litre/h (314 mg/dl/h). The ponies were assigned to four groups based on insulin and glucose response: Group 1 (n=7), normal; Group 2 (n=5), high insulin, normal glucose; Group 3 (n=8), high insulin, high glucose and Group 4 (n=3), high glucose, normal insulin. This classification is an initial attempt to define normal insulin and glucose response in ponies. Additional data need to be accumulated to define further insulin resistance and diabetes in ponies.
Evaluation of sodium hyaluronate therapy in induced septic arthritis in the horse
Authors: BRUSIE R. W. , SULLINS K. E. , II N. A. WHITE , COFFIN P. C. , PARKER G. A. , ANVER M. R. , ROSENBERGER J. L.
Published: June 2010

This study was conducted to determine the efficacy of sodium hyaluronate (SH) with antibiotic therapy and joint lavage for reducing acute inflammatory and degenerative changes induced by septic arthritis. Septic arthritis was induced in six adult horses by inoculating the tarsocrural joints with 1 times 104colony‐forming units ofStaphylococcus aureus. When clinical signs appeared, trimethoprimsulphamethoxazole (30 mg/kg bodyweight [bwt] daily) and phenylbutazone (4.4 mg/kg bwt sid) were administered and continued until termination of the study (Treatment Day 18). Twenty‐four hours post inoculation, all joints were lavaged with sterile lactated Ringer's solution. Following lavage, one joint of each horse was injected with 10 mg of SH, and the contralateral joint served as the control. Sodium hyaluronate treated joints showed significant reductions in lameness, tarsal circumference and synovial fluid protein and WBC concentrations. The synovial membrane of the SH‐treated joints contained less cellular infiltrate, less granulation tissue formation and retained a more normal villous structure compared with controls. The total glycosaminoglycan loss from the articular cartilage in the SH treated joints was consistently less than that from the control joints; however, this difference was not statistically significant. Sodium hyaluronate with joint lavage appears to be more beneficial than lavage alone for treatment of septic arthritis.
Cardiovascular effects of dopexamine HCI in conscious and halothane‐anaesthetised horses
Authors: III W. W. MUIR
Published: June 2010

The cardiovascular effects of serial increasing infusions of dopexamine HCI were investigated in six conscious (1, 2, 4, 6, 10 μg/kg bodyweight [bwt]/min) and eight (0.5, 1, 5, 10, 20 μg/kg bwt/min) halothane‐anaesthetised horses. Dopexamine produced dose‐dependent increases in heart rate, +dP/dtmax'‐dP/dtmaxand cardiac output, and a decrease in systemic vascular resistance in conscious and halothane‐anaesthetised horses. Mean arterial blood pressure did not change in conscious horses but increased to a maximum value at 10 μg/kg bwt/min in halothane‐anaesthetised horses. Thereafter, median artery blood flow decreased. Ventricular arrhythmias occurred in two conscious horses during the infusion of 10 μg/kg bwt/min dopexamine HCI. No cardiac arrhythmias other than sinus tachycardia were observed in halothane‐anaesthetised horses. The administration of propanolol eliminated the haemodynamic response to the infusion of 5 and 10 μg/kg bwt/min dopexamine HCI in halothane‐anaesthetised horses. The haemodynamic effects of dopexamine HCI offer specific advantages over dopamine and dobutamine for the treatment of low cardiac output states in horses.
The effects of famotidine, ranitidine and magnesium hydroxide/aluminium hydroxide on gastric fluid pH in adult horses
Authors: MURRAY M. J. , GRODINSKY CAROLYN
Published: June 2010

Gastric fluid pH was measured in five adult horses following nasogastric administration of famotidine, 0.5, 1.0, and 2.0 mg/kg bodyweight (bwt); ranitidine, 4.4 and 6.6 mg/kg bwt and an antacid containing magnesium hydroxide (40 mg/ml) and aluminium hydroxide (45 mg/ml), 120 and 180 ml. Fluid was aspirated through a 16 French nasogastric feeding tube at 15 min intervals, and pH was measured using a pH meter. Basal gastric fluid pH was measured at 20 min intervals for 6 h in each horse and, with the exception of two measurements of 4.66 and 4.17, ranged from 1.42 to 2.41, with a mean pH of 1.88 ± 0.18. The response to both ranitidine and famotidine was variable between horses and between dosages. The mean gastric fluid pH values following administration of a single dose of famotidine or ranitidine were famotidine, 0.5 mg/kg bwt, 3.63 ± 1.72; famotidine, 1.0 mg/kg bwt, 3.41 ± 1.40; famotidine, 2.0 mg/kg bwt, 4.18 ± 2.06; ranitidine, 4.4 mg/kg bwt, 4.07 ± 1.25; ranitidine, 6.6 mg/kg bwt, 5.34 ± gastric fluid pH between famotidine dose levels and between ranitidine dose levels were not significant (P>0.10). Gastric fluid pH increased to greater than 6 in three horses receiving 0.5 mg/kg bwt, five horses receiving 1.0 mg/kg bwt and three horses receiving 2.0 mg/kg bwt famotidine. Gastric fluid pH increased to greater than 6 in each of the five horses receiving 6.6 mg/kg bwt ranitidine and in four of five horses receiving 4.4 mg/kg bwt ranitidine. During the 6 h post administration, ranitidine tended to increase gastric fluid pH greater than 6 longer (166 ± 106 mins) than famotidine (98 ± 110 mins) and this difference was nearly significant (P=0.054). The response to antacid was variable and consistently short‐lived. The mean gastric fluid pH values for 6 h after administration of 120 ml or 180 ml were 2.42 ± 0.71 and 2.44 ± 0.47, respectively. Gastric fluid pH increased to greater than 6 in only two horses, for 15 and 30 mins, respectively. The increase in gastric fluid pH was significantly greater for ranitidine (P<0.001) and famotidine (P<0.02) than for antacid. The duration of the effect was significantly longer for ranitidine doses (P<0.001) and nearly so for famotidine doses (P<0.055) than for antacid.
The influence of surgery and anaesthesia on the pharmacokinetics of pethidine in the horse
Authors: WATERMAN AVRIL E. , AMIN A.
Published: June 2010

The plasma concentration of pethidine was measured in 16 horses, after its administration intravenously (iv) at a dose rate of 1 mg/kg bodyweight (bwt). In eight animals studied before surgery, the plasma levels of the drug decreased in a biexponential manner with a distributive half life of 3 mins and an elimination half life of 57.7 mins. Total body clearance was 17.7 ml/kg bwt/min. The remaining horses were investigated immediately after a period of anaesthesia and surgery and in these animals the drug exhibited smaller volumes of distribution (V1cand Vdarea) and a significantly lower clearance rate of 12.8 ml/kg bwt/min in these animals. Correlation between the plasma concentration of pethidine and information published previously on the duration of action of the agent in the horse suggests that plasma levels of approximately 0.4 μg/ml are required to produce analgesia in this species.
Influence of feeding schedule on the absorption of orally administered flunixin in the horse
Authors: WELSH J. C. M. , Lees P. , Stodulski G. , Cambridge H. , Foster A. P.
Published: June 2010

The effects of access to hay and of restricted feeding on the pharmacokinetics of flunixin administered orally to six healthy ponies were compared in a cross‐over study. No access to feed for a few hours before and after flunixin administration resulted in rapid absorption with a mean peak plasma concentration of 2.84 ± 0.28 μg/ml attained in an average time of 0.76 ± 0.18 h, followed by an exponential decline in plasma concentration. A lower peak plasma concentration was obtained when ponies had free access to hay before and after drug dosing. The mean maximum concentration (Cmax) was 1.30 ± 0.23 μug/ml and maximum time (tmax) was prolonged to a mean time of 7.66 ± 1.74 h. Free access to hay reduced and delayed the peak plasma concentration resulting in two or three separate concentration peaks in some ponies. The mean area under the plasma concentration‐time curve was not significantly different for the two feeding regimens.
Review Article: The role of equine strongyles in the pathogenesis of colic and current options for prophylaxis
Authors: Love S.
Published: June 2010

Equine strongyles have been shown to induce alterations in both mesenteric blood flow and also intestinal motility patterns. Both of these pathophysiological events might play a role in the pathogenesis of colic and it is likely that they are interrelated. The prevalence of strongyle‐associated colic is difficult to ascertain: non‐strangulating infarction is uncommon but many other colic episodes may be induced by strongyle infections. In controlled studies and in clinical accounts worm control programmes have resulted in a reduced prevalence of colic. Current options for adequate control of equine strongyles are: interval anthelmintic treatments; strategic anthelmintic treatments; selective anthelmintic treatments; daily in‐feed treatments and pasture hygiene.
Review Article: The role of tumour necrosis factor in the pathogenesis of equine colic
Authors: Morris Debra Deem
Published: June 2010

A large body of evidence in experimental animals, people and now horses supports the hypothesis that tumour necrosis factor (TNF) is an important proximal mediator of endotoxaemia. Because morbidity and mortality of colic in horses are associated with the escape of lipopolysaccharide into the peripheral blood, TNF may be the trigger to the complex cascade of events that is ultimately deleterious to the host. Clinical trials of inhibiting TNF with monoclonal antibodies in human septic shock patients are being undertaken. A similar approach to treating colic in horses is warranted.
Morbidity associated with abdominocentesis — a prospective study
Authors: Siex Monique T. , Wilson Julia H.
Published: June 2010

Abdominocentesis is performed routinely in the assessment of the equine colic patient; however, the incidence of complications from this procedure has not been firmly established. Specific information was solicited from cases at the University of Florida Veterinary Medical Teaching Hospital (UFVMTH) whenever abdominocentesis was performed: 1) person performing tap (student, resident or faculty); 2) instrument used; 3) site and number of taps performed and 4) characteristics of fluid obtained (if any). Clinical records were reviewed to determine antibiotic usage, clinical or surgical diagnosis and evidence of bowel or body wall damage subsequent to abdominocentesis. Enterocentesis occurred in 7 cases of 124 (representing 188 abdominocentesis attempts) and resulted in peritonitis in 2 horses and abdominal wall cellulitis in one. All 7 were found to have distended bowel at the time of abdominocentesis on the basis of rectal palpation or surgery performed immediately after abdominocentesis. The peritonitis in 2 horses was resolved with antibiotic therapy (penicillin and gentamycin) as was the abdominal wall cellulitis following both broad spectrum antibiotic usage and local hydrotherapy. No greater risk of enterocentesis was associated with students. Use of needles vs teat cannulas resulted in a very slightly greater rate of enterocentesis (5.7% vs 3.1%) (no significant difference). We conclude that there is a slight risk for abdominocentesis in horses with distended bowel.
A review of 38 cases of small colon obstruction in the horse
Authors: Edwards G. B.
Published: June 2010

Of 900 horses undergoing colic surgery, 38 (4.2%) had obstruction of the small colon. The important anatomical features of the small colon, the types of obstruction encountered and the clinical signs are described together with the laparotomy findings and surgical techniques used to overcome the obstructions. Of the 38 horses, 27 (71.0%) recovered and were discharged from the hospital.