bluuebunny/crossref_metadata_2025 huggingface dataset:
Distribution of ground reaction forces of the concurrently loaded limbs of the Dutch Warmblood horse at the normal walk
Authors: MERKENS H.W. , SCHAMHARDT H.C.
Published: April 2010

The distribution of the ground reaction forces (GRF) over the concurrently loaded limbs of the normally walking horse was determined from ‘representative’ GRF patterns of all limbs, which were plotted in correct time order after analysis of simultaneously taken high‐speed film. This procedure visualises the GRF patterns of each of the four limbs in relation to the GRF pattern(s) of the one or two concurrently loaded limb(s) during a complete stride. In 15 clinically sound horses the mean averaged GRF data and temporal stride parameters showed an almost complete symmetry between both the forelimbs and both the hindlimbs and resulted in a load distribution during the first half of the stride being almost identical to those in the second half of the stride. The transverse horizontal force (Fx) was maximum during the unilateral support phase. No more than one limb at a time contributed to either the deceleration or acceleration longitudinal horizontal (Fy) force. The total vertical (Fz) force of the concurrently loaded limbs during a complete stride fluctuated between 7 to 12 N/kg body weight. In a left forelimb lame horse, the decreased GRF amplitudes were compensated by increased GRF amplitudes in the three other limbs during both the swing phase and stance phase of the lame limb. Due to alterations of both GRF data and temporal stride parameters of the lame limb, as well as the three other limbs, the distribution of the GRF during the complete stride was changed dramatically.
Effect of exercise on the partitioning of equine respiratory resistance
Authors: ART T. , SERTEYN D. , LEKEUX P.
Published: April 2010

Pleural, tracheal, pharyngeal and mask pressures as well as airflow and tidal volume of five ponies on a treadmill (incline 8.3°) were recorded simultaneously while resting, walking, trotting slowly, trotting fast, after standing for 30 secs and 5 mins after the end of the exercise. The curves obtained were used to calculate total pulmonary resistance (RL), lower airway resistance (RLA) and upper airway resistance (RUA). The latter was also divided into nasal resistance (Rnas) and laryngeal plus extrathoracic tracheal resistance (Retr+lar). Furthermore, the inspiratory and expiratory components of each of these R values were estimated. Levels of RL, RLA and RUA were increased significantly during exercise but, during the recovery period, the values were significantly lower than those pre‐exercise. RUA represented 82 per cent of RL at rest and this percentage did not change significantly during and after exercise. The nasal resistance to RUA ratio was always higher than 0.5. The fact that RL increased with exercise intensity was due to the increase of RUA during inspiration, and mainly a result of the increase of RLA during expiration. At fast trot, RLA represented 5 and 50 per cent of RL during inspiration and expiration respectively. It was concluded that heavy exercise induces in ponies an increase of RL, one reason for which could be the partial collapse of the extrathoracic and intrathoracic airways during inspiration and expiration respectively.
Detomidine: A preliminary analysis of its duration of action in the horse by variable interval responding
Authors: WOOD T. , WECKMAN T. , WOODS W. E. , TOBIN T. , DOUGHERTY J.
Published: April 2010

Variable interval (VI) reinforcement scheduling is a specific type of operant conditioning that is sensitive to drug effects even when overt clinical signs of the drug have diminished. Six horses were conditioned to break a light beam with a head‐bobbing movement and this behaviour was reinforced with a reward of clean oats (approximately 30 mg/reinforcement). Initial training procedures included familiarisation with the behavioural equipment and fixed‐ratio reinforced scheduling. To establish baseline rates of behaviour, the horses were converted to a variable interval (60 sees) reinforcement schedule and kept on this schedule for the remainder of the study. A within subjects cross‐over design was used with three treatments counterbalanced with the six horses. Detomidine (40 μg kg body weight, xylazine (1.1 mg/kg bodyweight) and saline (10 ml) were administered intravenously on Monday mornings with VI responding rates measured during a routine 30 min session each day from Monday to Friday. Responses and reinforcements were recorded and dispensed by use of an electromechanical relay system wired to an electric eye, an automatic feeder and a programming and recording system. Xylazine produced a small decrease in responding rates at 1 h post dose, while detomidine treated horses showed a dramatic decrease in responding rates after 1 h and a lingering effect at 24 h. No long range effects were seen with either treatment and all horses returned to baseline responding rates by 48 h post dose.
Application of cloned fragments of equine herpesvirus type‐1 DNA for detection of virus‐specific DNA in equine tissues
Authors: MORRIS CLAIRE M. , FIELD H. J.
Published: April 2010

Tissue specimens obtained from equine herpesvirus‐1 (EHV‐1), subtype 1‐infected aborted foetuses were analysed for the presence of virus DNA by means of Southern blot and dot blot hybridisations. The specificity of the methods was confirmed although the sensitivity was inferior to classical techniques such as virus isolation. However, the possibility of detecting the state of the virus DNA and the ability to distinguish between subtypes were important features, and the dot blot method was shown to have potential for a rapid diagnostic test. This report demonstrates some potential practical applications of hybridisation methods for studying the pathogenesis and epidemiology of EHV‐1 but also reveals limitations of the techniques.
Characterisation of IgE‐mediated histamine release from equine basophilsin vitro
Authors: MAGRO A. M. , RUDOFSKY U. H. , SCHRADER W. P. , PRENDERGAST J.
Published: April 2010

In vitroIgE‐mediated histamine release by equine blood basophils was characterised as the basis for a screening test for immediate hypersensitivity responses in horses. The responses are initiated by inducing agents that are capable of crosslinking or bridging the membrane‐bound IgE molecules. The release process is complete within 40 mins.In vitrohistamine release is dose‐dependent, with a submaximal response at less or greater than the optimal dose of inducing agent. Exogenous calcium is required but not magnesium; the optimal release calcium concentration is 1.0 to 1.5 mM. If an IgE‐mediated inducing agent is added in the absence of exogenous calcium, the basophils become desensitised. The pH and temperature optima for release are physiological (pH 7.4, 37°C). Histamine release is potentiated by deuterium oxide.
The nutritional status of pregnant and nonpregnant mares grazing South East Queensland pastures
Authors: GALLAGHER J. R. , McMENIMAN N. P.
Published: April 2010

It has been reported that the increasing nutritional demands from mid to late pregnancy of grazing mares may not be met when these stages of gestation coincide with pastures being affected by frost. It was established in this study that grass/legume pastures could support the nutritional requirements of brood mares by providing digestible energy intakes of 68.0 and 91.7 MJ/day and digestible nitrogen intake of 91.2 and 138 g/day during mid and late pregnancy, respectively.
Plasma cell numbers in uteri of mares with persistent endometritis and in ovariectomised mares treated with ovarian steroids
Authors: WATSON ELAINE D. , STOKES C. R.
Published: April 2010

Immunoglobulins A, G and M were localised by immunoperoxidase staining of endometrial sections from ovariectomised mares. Treatment with progesterone or oestradiol‐17β did not significantly affect numbers of cells secreting any of the isotypes. Mares with persistent endometritis did not have significantly greater numbers of endometrial plasma cells than genitally‐normal mares.
Preferred landing sites of Culicoides species (Diptera: Ceratopogonidae) on a horse in Israel and its relevance to summer seasonal recurrent dermatitis (sweet itch)
Authors: BRAVERMAN Y.
Published: April 2010

Six hundred and twenty culicoides of five species were collected from a bait horse at Kannot, Israel, between April and September 1986. Seventy‐two per cent of the midges were collected from the belly and 27 per cent from the dorsal aspect of the body, ie, the sweet itch summer seasonal recurrent dermatitis (SSRD) zone. Midges were active mainly from half an hour prior to half an hour after sunset. Only Culicoides puncticollis, C imicola and C schultzei group were collected in considerable numbers. While C imicola was present continuously throughout the season, the appearance of the two other species was intermittent. Ninety‐five per cent of C schultzei group and approximately 100 per cent of the C puncticollis prefer to land on and most probably bite the belly. Culicoides imicola showed a clear preference for the dorsal ridge which overlaps the (SSRD) itch zone, and 70 per cent of the midges were collected there, while 28 per cent were collected from the belly. A considerably high proportion of the midges of this species were parous, ie, part of the population lived long enough to bite more than once. Skin temperature measurements showed the belly to be the warmest part of the body. Wind speeds of two to three knots reduced the number of midges collected. The findings of this study, together with a previous one (Braverman et al 1983), incriminate C imicola as the likely principal agent of SSRD in Israel.
Circulatory and muscle metabolic responses to draught work compared to increasing trotting velocities
Authors: GOTTLIEB M. , ESSÉN‐GUSTAVSSON B. , LINDHOLM A. , PERSSON S. G. B.
Published: April 2010

Circulatory and muscle metabolic responses were studied in 10 horses which all performed incremental draught work at a low trotting speed on a treadmill (D‐test) and also exercise with gradually increasing velocities (S‐test). Exercise was continued until the horses could no longer maintain the weights above the floor or maintain speed trotting without changing gait to a gallop. Muscle biopsies were taken from the gluteus and the semitendinosus muscles before, and immediately after, exercise. The heart rate (HR) increased linearly with both increasing draught resistance and velocity and reached mean values of 212 and 203 beats/min, respectively. Blood lactate levels increased exponentially to mean values of 12.9 and 7.9 mmol/litre in the two tests. Both HR and blood lactate levels were significantly higher at the cessation of work in the D‐test compared to the S‐test. The relationship between HR and blood lactate response in the S‐test was similar to that in the D‐test. The red cell volume was determined after a standardised exercise tolerance test and was significantly correlated both to the weightloading and to the velocity, producing a HR of 200 beats/min. The changes seen in muscle glycogen and glucose‐6‐phosphate were similar in the two tests, whereas significantly higher lactate levels and lower creatine phosphate and adenosine triphosphate levels were seen in the D‐test compared to the S‐test. It was concluded that high oxidative capacity is of importance both for fast trotting and for draught work. Glycolysis with lactate accumulation and Phosphagen breakdown is greater during a shorter trotting distance and at a much lower trotting speed during exercise with incremental draught loading, than during exercise with increasing velocities.
Equine neutrophil locomotion in response toStreptococcus zooepidemicus
Authors: PYCOCK J. F. , ALLEN W. E.
Published: April 2010

The neutrophil is involved in the defence of the mare's uterus against micro‐organisms. The ability ofStreptococcus zooepidemicusand its growth products to induce shape changes or directional locomotion (Chemotaxis) of equine neutrophils was investigated; no effect was found.
Use of high‐speed cinematography and computer generated gait diagrams for the study of equine hindlimb kinematics
Authors: KOBLUK C. N. , SCHNURR D. , HORNEY F. D. , SUMNER‐SMITH G. , WILLOUGHBY R. A. , DEKLEER V. , HEARN T. C.
Published: April 2010

High‐speed cinematography with computer aided analysis was used to study equine hindlimb kinematics. Eight horses were filmed at the trot or the pace. Filming was done from the side (lateral) and the back (caudal). Parameters measured from the lateral filming included the heights of the tuber coxae and tailhead, protraction and retraction of the hoof and angular changes of the tarsus and stifle. Abduction and adduction of the limb and tarsal height changes were measured from the caudal filming. The maximum and minimum values plus the standard deviations and coefficients of variations are presented in tabular form. Three gait diagrams were constructed to represent stifle angle versus tarsal angle, metatarsophalangeal height versus protraction‐retraction (fetlock height diagram) and tuber coxae and tailhead height versus stride (pelvic height diagram). Application of the technique to the group of horses revealed good repeatability of the gait diagrams within a limb and the diagrams appeared to be sensitive indicators of left/right asymmetries.
Serum amyloid A protein (SAA) in horses: objective measurement of the acute phase response
Authors: PEPYS M. B. , BALTZ MARILYN L. , TENNENT GLENYS A. , KENT JOYCE , OUSEY JENNIFER , ROSSDALE P. D.
Published: April 2010

A sensitive and precise immunoassay for equine serum amyloid A protein (SAA) was established and used to determine, for the first time, the circulating concentration of this protein in health and disease. As in other species, equine SAA was present only at trace levels in healthy animals but behaved as an extremely sensitive and rapidly responding acute phase reactant following most forms of tissue injury, infection and inflammation, objectively reflecting the extent and activity of disease. Measurements of SAA should make a significant contribution to diagnosis and management of viral and bacterial infection in horses, and routine serial assays could provide an objective criterion for monitoring prospectively the general health of horses in training and racing.
Androgen and oestrogen response to a single injection of hCG in cryptorchid horses
Authors: SILBERZAHN P. , POURET E. J.‐M. , ZWAIN I.
Published: April 2010

Androgen (testosterone and androstenedione) and oestrogen (oestradiol −17β and oestrone) concentrations were measured by radio‐immunoassay in the peripheral plasma of two geldings (five‐years‐old), three bilateral cryptorchids (two, two and a half, and five‐years‐old) and three normal intact stallions (four, five and five and a half‐years‐old) before and after a single injection of 10,000 iu human chorionic gonadotropin (hCG). In the stallions, hCG administration resulted in an immediate sharp increase of conjugated oestrogens and a more gradual increase of unconjugated androgens. In the cryptorchids, the unconjugated androgens increased following a similar pattern to that observed in the stallions, but reached lower peak values, whereas the conjugated oestrogens showed only a very slight increase. In the stallions and cryptorchids, the maximum oestrogen levels were reached two days after injection, whereas the maximal levels for androgens were reached a day later. In the geldings, hCG injection had no effect on plasma steroid levels. It is suggested that the measurement of unconjugated androgens (testosterone or/and androstenedione) before and three days after intravenous injection of 10,000 iu hCG may prove useful for the diagnosis of cryptorchidism or exploration of testicular function in stallions.
Pneumonia, lung abscesses and pleuritis in adult horses: a review of 51 cases
Authors: MAIR T. S. , LANE J. G.
Published: April 2010

Case records are reviewed of 51 adult horses in which a diagnosis of pneumonia, pulmonary abscess or pleuritis had been made. Forty‐five horses were aflicted with pneumonia and/or pulmonary abscesses; in 11 of these the infection was primary, whereas in 34 it was secondary to another disease process (inhalation of food or saliva, thoracic trauma, generalised infection, airway disease, neoplasia or thromboembolism). Of the 11 horses with primary pulmonary infections, 10 appeared to be associated with a previous episode of stress; this took the form of long distance travel in eight cases. There was a statistically significant association between primary pneumonia and/or lung abscesses and the use of the horses, with the highest incidence in showjumpers. Eighteen horses had pleuritis, of which 12 were secondary to pneumonia or pulmonary abscesses, two to thoracic trauma and one to generalised avian tuberculosis. Three cases of primary pleuritis were identified.
Evaluation of three strip tests for measuring electrolytes in mares' pre‐partum mammary secretions and for predicting parturition
Authors: OUSEY JENNIFER C. , DELCLAUX MARIA , ROSSDALE P. D.
Published: April 2010

Three strip test kits which measure calcium and/or magnesium in mares' mammary secretions were compared and assessed for their accuracy in:‐ 1) measuring these electrolytes compared to standard laboratory measurements, and 2) predicting the time of parturition. Daily samples of mammary secretions were obtained pre‐partum from 35 Thoroughbred mares and allocated a score. Measurement of mammary secretion calcium and/or magnesium by the strip tests and laboratory methods correlated significantly (P<0.001). The results obtained for prediction of parturition were analysed by two methods. Method i) indicated that the majority of mares had a maximum score on the day of birth. However, the second method of analysis included all pre‐partum scores and this demonstrated that maximum scores occurred on more occasions prior to the day of birth than on the day of birth itself. The number of nights spent attending mares, and the percentage of occasions when foaling was missed, were also calculated for given strip test scores. The results indicate that the test kits are not particularly accurate in predicting time of parturition although they are a reliable means of measuring mammary secretion calcium and/or magnesium. It is suggested that the test kits may be more helpful by indicating when it is not necessary to attend mares at night.
Monorchidism in the horse
Authors: PARKS A. H. , SCOTT E. A. , COX J. E. , STICK J. A.
Published: April 2010

Six horses with monorchidism, identified at surgery for cryptorchidectomy, are reported. All six presented with a single scrotal testis. Following surgical removal of one testis, they were either hormonally, anatomically or behaviourally determined to be geldings. Three other horses reported in the literature are reviewed. Of these nine cases of monorchidism, eight were thought to be caused by testicular degeneration and one by testicular agenesis. The vaginal process was present in all of the former and absent in the latter. The left side was involved in five of these eight horses. In seven, the epididymis was absent and, in the remaining two, only the epididymal tail was present. The condition was thought to be congenital in the six horses in this series. A surgical approach to identify accurately monorchid horses is described.
Australian Stringhalt ‐ epidemiological, clinical and neurological investigations
Authors: HUNTINGTON P. J. , JEFFCOTT L. B. , FRIEND S. C. E. , LUFF A. R. , FINKELSTEIN D. I. , FLYNN R. J.
Published: April 2010

An investigation of 78 cases of typical Australian Stringhalt from 52 properties in Victoria was carried out from 1985 to 1987. Horses were either examined in the field (n = 52), referred to the Veterinary Clinical Centre (n = 13) or clinical details were obtained verbally (n = 13). In addition 10 cases of false or atypical stringhalt were examined. Detailed soil and pasture analysis was carried out on 14 properties where Australian Stringhalt had occurred. Information was also obtained on epidemiology of the condition from a survey of practitioners. Fifty of the 52 cases examined in the field occurred in horses that were dependent upon poor quality unimproved dry pasture. In all but a few cases, there was no pasture improvement or fertiliser application, leading to the development of weed‐dominated pastures, particularly by flatweed, Hypochaeris radicata. The range of clinical signs exhibited by horses with Australian Stringhalt was described and a grading system proposed to classify horses according to severity of signs. Laryngeal abnormalities were present in 10 of 11 cases examined endoscopically and these horses exhibited increased electromyographic (EMG) activity in the long digital extensor muscle at rest and during hindlimb flexion. To a large extent, the EMG changes disappeared and digital extensor muscle atrophy improved in two horses that were monitored to recovery. Deep peroneal nerve conduction studies in four horses with Australian Stringhalt showed a substantial reduction in nerve conduction velocity and when stimulated at 50 Hz were unable to sustain activation of the long digital extensor muscle. EMG and evoked responses appeared to be sensitive indicators of the state of the disease. Spontaneous recovery over a period ranging from a few days to over 18 months occurred in 78 per cent (45 out of 58) of field cases available for follow up, although eight horses were destroyed on humane grounds or for pathological investigation.
Analysis of post mortem aqueous humour chemistry in the horse, with particular reference to urea nitrogen and creatinine
Authors: CANTOR G. H. , PALMER G.H. , FENWICK B. W.
Published: April 2010

The concentrations of several post mortem aqueous humour chemical constituents were compared with ante mortem serum chemical values in the horse. Urea nitrogen and creatinine values in post mortem aqueous humour were good predictors of ante mortem serum values. Aqueous humour urea nitrogen increased only slightly and creatinine did not change significantly for up to 24 h after death. Formulae were derived for calculating estimated ante mortem serum urea nitrogen and creatinine from aqueous humour values obtained after death. These results from normal horses identify analytes that are accurate predictors of ante mortem serum values. Determination of post mortem aqueous humour urea nitrogen of creatinine may assist in interpretation of the functional significance of equivocal histological lesions in the kidney.
The arterial supply of the navicular bone in adult horses with navicular disease
Authors: RIJKENHUIZEN ASTRID B. M. , NÉMETH F. , DIK K. J. , GOEDEGEBUURE S. A.
Published: April 2010

A macroscopical, arteriographical and histological study was made of the arterial supply of the navicular bones of horses with clinical and/or radiographic signs of navicular disease. Based on the clinical and radiological findings the navicular bones of 40 Warmblood horses are divided into four different groups. In the pattern of the arteriogram obvious changes are noticed: an imbalance and a distal to proximal shift between the distal and proximal arterial supply occur, indicating a reduction of the distal blood supply with a compensatory reaction of the proximal, medial and lateral supply. The changes in the pattern of the arteriogram are histologically defined by arterio(lo) sclerosis and newly formed arteries. The presence of radiologically visible nutrient foramina is associated with a changed pattern in the arteriogram, increased bone remodelling and fibrosis. Ischaemia and increased pressure (hypertension and/or increased intra‐articular pressure) are considered to be responsible for changes in form and number of radiologically visible nutrient foramina.
Navicular bone disease: a comparative histomorphometric study
Authors: ØSTBLOM L. , LUND C. , MELSEN F.
Published: April 2010

Twelve horses suffering from navicular bone disease were examined in a prospective, controlled histomorphometric study for six months. The objective was to compare the histology of navicular bones from untreated animals to those treated with the egg‐bar shoeing technique. These data were compared to similar sections from three normal animals. The current investigation provided quantitative support to previous findings concerning clinical improvement. Detailed histology, changes in bone morphometry and pathophysiological reactions are discussed.
Laryngotracheal lesions following routine orotracheal intubation in the horse
Authors: HEATH R. B. , STEFFEY E. P. , THURMON J. C. , WERTZ E. M. , MEAGHER D. M. , HYYPPA T. , Van SLYKE G. L.
Published: April 2010

Sequelae of routine orotracheal intubation under clinical conditions were characterised in 38 healthy horses presented at three veterinary medical teaching hospitals. Four of these were necropsied and their tissues studied histologically. To minimise variation, 30 mm id cuffed silicone endotracheal tubes or Cole cuffless tubes were used in all patients. Fibreoptic endoscopic examination of upper respiratory and tracheal areas was accomplished pre‐intubation, immediately post extubation and after 24 h. Endoscopy revealed that intubation was associated with laryngeal and/or tracheal lesions in all horses. Observations included abundant tracheal mucus, epithelial ecchymoses, basement membrane haemorrhage and mucus covered diphtheritic membrane plaques. Histological examination of lesions from the upper respiratory system of the four necropsied horses confirmed that the damage was comparable to that associated with tracheal intubation and reported in other species.
Further experiences with non‐surgical correction of nephrosplenic entrapment of the left colon in the horse
Authors: KALSBEEK H. C.
Published: April 2010

Non‐surgical correction of nephrosplenic entrapment of the left colon was attempted in 27 cases. In two cases the method failed and a laparotomy was necessary. Two other horses had a recurrence, one of which underwent laparotomy because of torsion of the caecal body.
The influence of corticosteroids on sequential clinical and synovial fluid parameters in joints with acute infectious arthritis in the horse
Authors: TULAMO RIITTA‐MARI , BRAMLAGE L. R. , GABEL A. A.
Published: April 2010

Infectious arthritis was induced experimentally in one tarsocrural joint of six horses by intra‐articular injection of 1 mlStaphylococcus aureus‐saline suspension with the addition of 200 mg methylprednisolone acetate. The corresponding contralateral joint was injected with 1 ml of saline with the addition of 200 mg methylprednisolone acetate, and served as a control. The purpose of the experiment was to examine the effect of corticosteroids on the acute clinical signs of infectious arthritis, and the associated changes in synovial fluid, to separate the effects of a steroid injection from those of infection alone. This should aid early diagnosis of infection. The progression of the infectious arthritis was assessed over nine days by clinical examination and sequential synovial fluid analysis. The corticosteroids masked the clinical signs in some horses for up to the third day although changes in the synovial fluid were present earlier. Cellular changes preceded biochemical changes initially. Leucocyte counts showed a significant increase in cell numbers after infection was established. Persistent neutrophilia, over 90 per cent, together with a pH under 6.9 were the most consistent findings in the infected synovia. Total protein values were lower in infected joints with, than those without, corticosteroids; although there was a progressive rise in total protein concentration throughout the experiment in both groups. Serum and synovial glucose difference and synovial lactate had very little diagnostic value because significant increases due to the corticosteroids were documented in the control joints.
Isolation of A/Equi‐2 virus during 1987 equine influenza epidemic in India
Authors: UPPAL P. K. , YADAV M. P. , OBEROI M. S.
Published: April 2010

Processing of nasal materials from clinical cases during the 1987 influenza epidemic in Northern and Central India resulted in the isolation of two haemagglutinating agents; one each from donkeys and horses at Bhiwani in Haryana State and Ludhiana in Punjab State, respectively. These were typed as Influenza A/Equi‐2 viruses by haemagglutination inhibition test. The two isolates were designated as A/Equi‐2/Bhiwani/1/87 and A/Equi‐2/Ludhiana/1/87. The Bhiwani/87 isolate was confirmed to have H3N8 antigenic structure and was indistinguishable from the Miami/63 strain of A/Equi‐2 virus. However, the A/Equi‐2 Ludhiana/87 isolate was closely related to the Fontainebleau/79 strain of A/equi‐2 virus.
The construction of the heart bar shoe and the technique of dorsal wall resection
Authors: EUSTACE R. A. , CALDWELL M. N.
Published: April 2010

This paper describes a method of fabricating and fitting heart bar shoes and a technique of dorsal hoof wall resection. The rationale behind the treatments and criteria for their use are described. Radiographic technique is also discussed. This article reports the treatment of a series of clinical cases described in an accompanying article (p370).
Effect of Palosein (superoxide dismutase) and catalase upon oxygen derived free radical induced degradation of equine synovial fluid
Authors: AUER D. E. , NG J. C. , SEAWRIGHT A. A.
Published: April 2010

The effect of oxygen derived free radicals (ODFR) upon the specific viscosity of equine synovial fluid was studied. ODFR were generated either by a mixture of ferrous iron and EDTA (Fe/EDTA) or by a mixture of hypoxanthine and xanthine oxidase (HX/XO). Incubation of the synovial fluid with both free radical generating systems decreased its specific viscosity. When the synovial fluid was incubated with Fe/EDTA the specific viscosity of the synovial fluid was reduced rapidly. By 2 mins, it was 53±3 per cent of the original specific viscosity and by 30 mins it was reduced to 39±5 per cent. In the HX/XO system, the specific viscosity was 75±4 per cent of the original specific viscosity at 10 mins and by 50 mins it was reduced to 55±3 per cent. Palosein (superoxide dismutase) was an effective inhibitor of the free radical induced reduction of the viscosity of the synovial fluid when the free radicals were generated with HX/XO but not with Fe/EDTA. Catalase was moderately effective as an inhibitor of reduction in specific viscosity of the synovial fluid when the free radicals were generated by either system. Only minor synergy resulted when mixtures of Palosein and catalase were tested for inhibition of Fe/EDTA induced reduction in the specific viscosity of equine synovial fluid. The results indicate that Palosein may protect equine synovial fluid from the effects of the superoxide radical (02−) but not from the hydroxyl radical (OH*). It was suggested that catalase may be a more appropriate antioxidant for the treatment of inflammatory disorders of the joint because it provided moderate protection from both ODFR producing systems. In addition, it was suggested that Palosein will not directly protect equine synovial fluid in vivo against ODFR generated by iron in the absence of superoxide, although it may provide protection through a secondary role by inhibiting mobilisation of iron and the reduction of ferric ions in vivo.
The effect of phenothiazine on plasma prolactin levels in non‐pregnant mares
Authors: LOCH W. , WORTHY K. , IRELAND F.
Published: April 2010

Sixteen non‐pregnant pony mares were divided into four groups of similar age and bodyweight (bwt). Groups were randomly assigned to one of four treatments consisting of oral administration of perphenazine (0.5 and 1.0 mg/kg bwt, phenothiazine (10 mg/kg bwt) and a control group. Blood samples were taken by jugular venepuncture and plasma prolactin concentrations measured using an homologous assay for equine prolactin. Analysis of variance was conducted on data designed as a split plot over time. Perphenazine given orally (0.5 and 1.0 mg/kg bwt) increased plasma prolactin concentrations when measured 3 and 6 h following feeding (P < 0.05). Prolactin concentrations returned to normal by 11 h post drug administration. There was no response in plasma prolactin concentrations following oral phenothiazine treatment (10 mg/kg bwt). Perphenazine at the 1.0 mg/kg bwt level was discontinued after two days due to two mares exhibiting signs of hyperesthesia.
Relationships of total protein, specific gravity, viscosity, refractive index and latex agglutination to immunoglobulin G concentration in mare colostrum
Authors: WAELCHLI R. O. , HÄSSIG M. , EGGENBERGER E. , NUSSBAUMER MARLIES
Published: April 2010

A colostrum sample was collected within 24 h after foaling from 27 mares and from 10 other mares a milk sample was collected several weeks post partum. Immunoglobulin G concentrations were determined quantitatively by radial immunodiffusion and semi‐quantitatively using a commercial latex agglutination test. Total protein, specific gravity, viscosity and refractive index were determined and their relationships to the immunoglobulin G concentration analysed. All parameters correlated with the immunoglobulin G concentration. The latex agglutination test divided the colostrum samples into three groups with different means for immunoglobulin G and total protein concentrations. Specific gravity and the latex agglutination test were found to be the methods best suited for on‐farm evaluation of colostrum quality.
Experimental infection of ponies with equine influenza (H3N8) viruses by intranasal inoculation or exposure to aerosols
Authors: MUMFORD JENNIFER A. , HANNANT D. , JESSETT D. M.
Published: April 2010

Infection of seronegative Welsh mountain ponies was established by intranasal instillation or exposure to nebulised aerosol of egg grown H3N8 viruses. Pyrexia and coughing were noted following intranasal instillation and high titres of virus were recovered from the nasopharynx. Exposure to aerosol resulted in more severe clinical signs characterised by high temperatures, dyspnoea, anorexia and coughing; lower levels of virus were recovered from the nasopharynx. The severity of clinical signs and the kinetics of virus shedding were dose‐related with the minimal infectious dose being 102EID50/ml when ponies were exposed to aerosols produced by nebulisation of 20ml allantoic fluid. Full clinical signs only developed when ponies were exposed to a dose of 106EIU50/ml. It was concluded that exposure to nebulised aerosols of egg grown H3N8 viruses was a more reliable method of inducing clinical influenza than intranasal inoculation and would be more suitable for challenge studies.
Impedance plethysmography
Authors: ATTENBURROW D. P. , FLACK F. C. , PORTERGILL M. J.
Published: April 2010

The technique of impedance plethysmography is described and its application to observation of lung volume changes in the horse at exercise is discussed. The results from horse at rest show that there is a close relationship between rate of lung volume change (flow rate) and the associated impedance changes during both inspiration and expiration. Impedance changes during exercise were related to inspiration and expiration by observation of associated respiratory sounds. Artefacts related to technical difficulties are also indicated.
Effects of exercise on serum aminotransferase activity and pyridoxal phosphate saturation in Thoroughbred racehorses
Authors: REJ R. , RUDOFSKY U. , MAGRO A. , PRENDERGAST J.
Published: April 2010

Aminotransferase activities were measured in the serum of two‐ to three‐year‐old Thoroughbred fillies and colts during a four week period of peak training for flat racing. Aspartate aminotransferase (AspAT, EC 2.6.1.1), mitochondrial aspartate aminotransferase (m‐AspAT) and alanine aminotransferase (AlaAT, EC 2.6.1.2) activities in serum were measured and the relative proportions of apoenzyme and holoenzyme were determined. The aminotransferase activities were increased only slightly immediately following exercise. This small and immediate post exercise increase in activity did not vary greatly over the period of peak training. Measured in the presence of exogenous pyridoxal 5’‐phosphate, mean enzyme activities (iu/litre at 30°C) before exercise were: AspAT, 291; m‐AspAT, 13; AlaAT, 18. After exercise they were: AspAT, 317; m‐AspAT, 16; AlaAT, 23. Nearly all of the AspAT activity was present in the holoenzyme form (94 per cent holoenzyme) indicating excellent vitamin B6 status in these animals. Paradoxically, the AlaAT in serum from the same highly trained Thoroughbred horses was poorly saturated with pyridoxal phosphate, with nearly half of the AlaAT in most horses present in the inactive apoenzyme form (61 per cent that of holoenzyme). It is critical therefore, that exogenous pyridoxal phosphate be included in aminotransferase assays to determine the amounts of enzyme release into the peripheral circulation.
Equine synovial tendon sheaths and bursae: an histological and scanning electron microscopical study
Authors: HAGO B. E. D. , PLUMMER J. M. , VAUGHAN L. C.
Published: April 2010

The structure of equine synovial tendon sheaths and bursae has been examined by light and scanning electron microscopy. Tissue samples were obtained from horses of various types and ages with no clinical evidence of sheath or bursal disorders. The interior of both structures was lined by a cellular layer superimposed on a vascular zone supported by a fibrous layer. The pattern of cell distribution of the lining varied from site to site within the same structure depending on the nature of the underlying tissue and on the amount of movement to which the structure was subjected. The cellular layer was predominantly fibrous in nature with scanty, widely separated fibroblasts (eg where it lines the palmar ligament, tendons and paratendons). In the mesotendon and bursal extremities, where the lining is subjected to a positive degree of movement, the cellular layer was areolar in type with well established folds populated by abundant cells oval to round in shape. In foals and yearlings, the supportive layer was mainly around the areolar with patches of adipose tissue; which were gradually replaced by fibrous tissue as the animal grew.
Ultrastructural findings in horses with chronic obstructive pulmonary disease (COPD) I: alterations of the larger conducting airways
Authors: KAUP F.‐J. , DROMMER W. , DEEGEN E.
Published: April 2010

Extensive light and electron microscope studies of the conducting airways were carried out in 28 horses with varying degrees of clinically manifested chronic obstructive pulmonary disease (COPD) and in 8 horses with normal lungs. The principal ultrastructural changes were found in the ciliated cells. There was focal loss of ciliated cells, which were replaced by undifferentiated cells in a largely hyperplastic epithelium, and some horses, independent of the degree of severity of the disease, showed various types of ciliary malformation. The finding of dilated intercellular clefts and accumulations of mast cells was interpreted as morphological evidence of non‐specific mucosal hyperreactivity. Interstitial cells with intracytoplasmal crystal inclusions, the cause of which is not clear, were seen in many horses. Comparison between the clinical diagnosis and the morphological findings showed partial correlation. The ciliary loss, the appearance of peribronchial inflammatory processes and the occurrence of intracytoplasmic crystalline inclusions showed a positive correlation. In 12 of 28 cases, the severity of clinical diagnosis agreed with the degree of the morphological findings. The changes in the conducting airways were interpreted pathogenetically as reactive processes to changes in the small airways in the course of equine COPD.
Peritoneal fluid values from healthy foals
Authors: GRINDEM C. B. , FAIRLEY N. M. , UHLINGER C. A. , CRANE S. A.
Published: April 2010

Peritoneal fluid was analysed from 17 foals, aged 13 to 134 days with a mean age of 68 days. Cytologically, the peritoneal fluid was characterised by a mean total cell count of 0.45 times 109/litre (range 0.06 to 1.42 times 109/litre), rare eosinophils, rare cytophagia and variable percentages of neutrophils and mononuclear cells. These data indicate that peritoneal fluid nucleated cell counts over 1.50 times 109/litre in the foal should be interpreted as elevated. Biochemical evaluation revealed a mean biuret protein level of 12 g/litre, mean refractive index protein level of 16 g/litre and urea nitrogen concentration of 1.96 mmol/litre. There was no correlation between the foals' white blood cell and peritoneal fluid nucleated cell counts. Results of this study indicate that adult horse reference values for evaluation of peritoneal fluid are of questionable validity for foals. Diagnostically, the most important observation was that maximum peritoneal fluid nucleated cell counts in healthy foals were much lower than reported maximal reference values for adult horses (1.5 times 109/litre versus 5.0 times 109/litre or 10.0 times 109/litre).
Left ventricular volume determination in the horse by two‐dimensional echocardiography: anin vitrostudy
Authors: VÖRÖS K. , HOLMES J. R. , GIBBS CHRISTINE
Published: April 2010

This study was designed to evaluate the accuracy of two‐dimensional echocardiography (2DE) in determining the left ventricular volume (LVV) of the horsein vitro.After examining the shape of the left ventricular silicon rubber casts of four equine hearts, two modified Simpson's rule methods (Model A and Model B) as combinations of conical shapes and one biplane area‐length method as a single cone (Model C) were chosen for volume calculations. One long axis and three short axis planes were used for linear and area 2DE measurements, respectively. The ventricular length (L) was calculated from the chordal length (CL) by using a linear regression equation (L = 5.54 + 1.83 CL) obtained by anatomical measurement of these two parameters on 40 normal hearts. The LVV was calculated in 15 formalin‐fixed hearts from 2DE measurements with the three geometric models. Left ventricular casts were then made using silicon rubber, and their volumes were determined by water displacement. The calculated volumes were plotted against cast volumes with linear regression analysis. All calculated LVVs correlated well with the cast LVVs (R = 0.921 to 0.957; P<0.001). The highest correlation was provided by Model A which best represented the shape of the left ventricle. This model consisted of a truncated cone bordered by the area at the level of the mitral valve and by the area at the level of the chordae tendineae, plus a cone the base of which was the area at the level of the papillary muscles. The results demonstrate the applicability of 2DE for equine LVV determinationsin vitro, similar to other species. The method requires further investigation in the living horse.
Effects of five hours of constant 1.2 MAC halothane in sternally recumbent, spontaneously breathing horses
Authors: STEFFEY E. P. , WOLINER M. J. , DUNLOP C.
Published: April 2010

Circulatory and respiratory effects of five h of constant 1.06 per cent alveolar halothane in oxygen were identified in eight healthy horses, which breathed spontaneously, were otherwise unmedicated and positioned in sternal recumbency. Only a few important significant (P<0.05) changes occurred with time. Total peripheral resistance was about 15 per cent lower after two hours of constant dose halothane than after 30 mins of constant dose (P<0.05) and accounted for the significant 10 per cent reduction in mean carotid arterial blood pressure. By 5 h, the reduction in resistance and arterial blood pressure was 20 and 25 per cent respectively. Heart rate increased progressively with time and the increase became significant at 5 h (15 per cent increase). However, the heart rate change was not large enough to alter cardiac output. There were no major time‐related changes in PaO2or PaCO2. Three of four horses recovered from anaesthesia had markedly elevated serum creatine kinase levels and clinical signs of severe post anaesthetic myopathy.
Cranial thoracic masses in the horse: a sequel to pleuropneumonia
Authors: BYARS T. D. , DAINIS C. M. , SELTZER K. L. , RANTANEN N. W.
Published: April 2010

The formation of cranial thoracic masses (CTM) as a sequel to infectious pleuropneumonia is described. Using ultrasound, masses were diagnosed subjectively as abscesses or loculations. Eight of 99 cases with pleuropneumonia had CTM. Clinical signs associated with the presence of a CTM included increased heart rate, jugular distention, forelimb ‘pointing’ and caudal displacement of the heart. Techniques used for diagnostic ultrasonographic examination of the cranial thorax are described. Five of the eight horses with CTM responded to conservative medical management; the other three required percutaneous drainage of the mass to relieve worsening signs of cardiac decompensation. Improvements in cardiovascular parameters were evident within 12 h of drainage. The indications for and limitations of invasive drainage of cranial thoracic masses are discussed.
The use of the walking cast to repair fractures in horses and ponies
Authors: NÉMETH F. , BACK W.
Published: April 2010

The walking cast was used to repair 46 fractures of long bones (distal radius and tibia, metacarpus and metatarsus) and 10 fractures of first phalanx of 35 horses and 21 ponies. The walking cast proved to be highly effective. Even heavily comminuted and ‘hopeless' fractures, which could not be treated with osteosynthesis, were treated successfully, because the weight of the animal, a common failure factor in large animal orthopaedics, was relieved from the injured leg. Immediate full weight bearing was possible post operatively. In five cases the walking cast was used in combination with osteosynthesis. Infection was the main complication that caused the walking cast to fail. Osteomyelitis may also be treated with a walking cast. Because of its success rate of 57 per cent, which is impressive, considering the type of fractures treated, we recommend the walking cast for international accreditation.
A comparison of techniques to enhance the evaluation of equine laryngeal function
Authors: ARCHER R. M. , LINDSAY W. A. , DUNCAN I. D.
Published: April 2010

This study was designed to define a simple, unequivocal test for the evaluation of laryngeal function and the diagnosis of idiopathic laryngeal hemiplegia (ILH). ILH is a disorder that results from left recurrent laryngeal neuropathy and in which there is no movement of the left arytenoid cartilage and vocal fold. Laryngeal function was evaluated in seven horses using four techniques designed to stimulate laryngeal movements:‐nasal occlusion, exercise, swallowing and administration of a respiratory stimulant. In addition, the effects of sedation and twitching on the endoscopic examination were also examined. The cross‐sectional area of the rima glottidis was measured in each horse at rest and after each technique was performed. There was no statistically significant difference in the increase in area seen after nasal occlusion or exercise. Doxapram hydrochloride increased the cross‐sectional area of the rima glottidis, whereas xylazine caused a decrease. Neither of these pharmacological agents exaggerated or decreased the amount of asynchronous movement or tremoring of the arytenoid cartilages. Manual occlusion of the external nares during endoscopy is a simple, yet effective method of stimulating arytenoid function and hence diagnosing ILH.