bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of high‐intensity exercise on plasma catecholamines in the Thoroughbred horse
Authors: SNOW D. H. , HARRIS R. C. , MACDONALD I. A. , FORSTER C. D. , MARLIN D. J.
Published: April 2010

In Study 1, a single speed test of 6 to 12 m/sec was performed for 2 mins at an incline of 5° on a high‐speed treadmill (single‐step test). Only one speed was performed per session and blood samples were taken before and after the test. In Study 2 horses cantered for 1 min at increasing speeds of 6 to 13 m/sec on an incline of 3° (multiple‐step test). Blood samples were taken before exercise, throughout the test and during recovery.

In the single‐step test plasma concentrations of adrenaline and noradrenaline both increased at speeds of 9 m/sec, as did blood lactate. Mean concentrations of adrenaline and noradrenaline at the end of the 12 m/sec test were 153 and 148 nmol/litre, respectively. Plasma concentrations were similar over all speeds although there was a tendency for the increase in noradrenaline to be greater than that of adrenaline at the lower speeds. The multiple‐step test resulted in smaller increases in both adrenaline and noradrenaline. Although again closely correlated, increases in adrenaline were 20–30% greater than those for noradrenaline.

In both exercise models, changes in plasma adrenaline and noradrenaline values with exercise showed an exponential relationship to plasma lactate. A plasma half‐life of less than 30 secs was indicated during recovery from the multiple‐step test. Changes in adrenaline and noradrenaline were much greater than previously recorded in man and emphasise the importance of catecholamines in mediating the physiological response of the horse to exercise.
Outcome of treatment in 23 horses with progressive ethmoidal haematoma
Authors: GREET T. R. C.
Published: April 2010

This paper describes the outcome of treatment in 23 horses with an ethmoidal haematoma. In 22 cases a diagnosis could be made by endoscopic means alone but in 1 horse the lesion was confined to the maxillary sinus and a diagnosis was made only at surgery. One horse was destroyed at the owner's request but the other 22 underwent radical excision of the lesion via a facial flap approach under general anaesthesia. Post‐operative haemorrhage was controlled by nasal packing with a gauze bandage and this was removed between the 2nd and 4th post‐operative day. One horse died from encephalitis the day after surgery. Other complications included facial wound dehiscence, sequestration and suture periostitis. Of 21 horses followed up post‐operatively there was definite recurrence of lesion in 2 cases and possibly a third. However, in 18 horses there was no evidence of recurrence (follow up times were 2 to 85 months). It is suggested that radical excision of the lesion provides an effective means of treatment.
Effect of dietary biotin supplement on equine hoof horn growth rate and hardness
Authors: BUFFA E. A. , VAN DEN BERG S. S. , VERSTRAETE F. J. M. , SWART N. G. N.
Published: April 2010

Over a 10‐month period, 24 randomly selected riding horses were fed various amounts of biotin. Statistically significant improvements in growth rates and hardness of hooves were produced by biotin supplementation. Greater growth rates and hardness were achieved at a daily dose of 15 mg than at 7.5 mg. Increased hoof hardness was greatest in the hoof quarters and toe. No ring formation occurred in hooves of horses fed biotin intermittently.
Ultrasonographic and histopathological findings in equine superficial digital flexor tendon injury
Authors: MARR CELIA M. , McMILLAN I. , BOYD J. S. , WRIGHT N. G. , MURRAY M.
Published: April 2010

The ultrasonographic and histopathological findings in 12 normal and 28 injured superficial digital flexor tendons, with lesions ranging in duration from 2 days to 15 months, were compared. A consistent relationship between the ultrasonographic and histological findings was demonstrated. The echogenicity of lesions, the distinctness of their delineation from the surrounding tissue, and the presence and arrangement of the linear echoes were useful features by which to assess the ultrasonograms. Acute lesions were anechoic, a complex mixture of anechoic and hypoechoic areas, or diffusely hypoechoic. These appearances represented haemorrhage, fibrolysis and early granulation tissue. Fibroplasia and granulation tissue produced well to moderately well defined hypoechoic lesions. Chronic fibrosis was characterised by heterogeneously echogenic areas which were poorly defined from the surrounding tissue and had irregularly‐arranged linear echoes on longitudinal images. Intratendinous scar formation resulted in multiple hyperechoic foci. Extensive peritendinous lesions were readily apparent on ultrasonograms, but intertendinous adhesions were more difficult to assess, and produced ill‐definition of the borders between the superficial and deep digital flexor tendons.
A method for loading equine platelets with the fluorescent calcium indicator Fura‐2: ADP induces a rise in the cytosolic free calcium ion concentration
Authors: POOLE A. W. , HEATH M. F. , SAGE S. O. , EVANS R. J.
Published: April 2010

Equine platelets in platelet‐rich plasma were incubated with the fluorescent indicator dye, Fura‐2‐AM (Fura‐2‐acetoxymethyl ester) and the degree of loading of the cells with the dye and the extent of hydrolysis of the ester was assessed by quantitative fluorimetry and by thin‐layer chromatography respectively. Under these conditions the cells loaded poorly with Fura‐2 to a concentration of 4 μM. The technique was validated by demonstrating adequate loading of human platelets with Fura‐2, to a concentration of 250–300 μM, using the same method. The removal of plasma from the extracellular medium was important for successful loading of the cells with the dye since washed cells resuspended in a physiological salt solution loaded adequately with Fura‐2 to a concentration of 190 μM. Cells loaded as such showed a resting [Ca2+]i of 129 nM and a concentration‐dependent rise in [Ca2+]i to a transient maximum of 350 nM when stimulated by the pro‐aggregatory agonist adenosine 5′‐diphosphate (ADP).
A retrospective evaluation of laminitis in horses
Authors: HUNT R. J.
Published: April 2010

Case records of 202 horses treated for laminitis were reviewed with the intent of determining the long‐term outcome and correlating this with digital radiographic findings and with the degree of pain associated with the laminitis. At long‐term follow‐up 57 horses had returned to athletic soundness (Group 1), 20 horses were intermittently lame (Group 2), 19 horses had permanent severe lameness (Group 3), 97 were dead (Group 4), and 9 were lost to follow up. Using simple regression analysis, functional outcome did not correlate with the degree of rotation (R2= 0.004) or the presence of distal displacement (R2= 0.139). Functional outcome did correlate with the clinical grade of laminitis (R2= 0.504). Horses in Group 1 had significantly less distal phalangeal rotation (5.89 ± 6.48 degrees) than did horses in Group 2 (11.10 ± 8.19) and Group 3 (14.50 ± 10.80), but were not significantly different from Group 4 horses (7.49 ± 6.57). Of 96 surviving horses, 23 had evidence of distal displacement compared with 54 of 97 non‐survivors. Based on these results, horses that develop distal displacement of the distal phalanx are more likely to die than are horses without distal displacement; however, the presence or absence of distal phalangeal displacement and the degree of distal phalangeal rotation cannot be used to predict the outcome of a horse with laminitis. Clinical assessment is a more reliable means of determining the final outcome and should be given precedence over radiographic findings.
Characterisation of equine influenza isolates from the 1987 epizootic in India by nucleotide sequencing of the HA1 gene
Authors: GUPTA A. K. , YADAV M. P. , UPPAL P. K. , MUMFORD JENNIFER A. , BINNS M. M.
Published: April 2010

Two A/Equi‐2 (H3N8) isolates were obtained during the 1987 Indian equine influenza epizootic. The sequence of the Ludhiana/87 HA1 gene revealed that this isolate was very similar to recent European and North American isolates of equine influenza. In contrast, the Bhiwani/87 HA1 gene was nearly identical to the Miami/63 prototype H3 sequence. These results support the antigenic analysis previously carried out on these isolates using monoclonal antibodies. However, the finding that Bhiwani/87 is so similar to Miami/63, coupled with the finding that equine H3N8 influenza viruses have previously been shown to evolve along a single lineage, suggests that Miami/63 virus from either a vaccine or laboratory source may be the origin of the Bhiwani/87 isolate.
Recognition ofPneumocystis cariniiin foals with respiratory distress
Authors: AINSWORTH DOROTHY M. , WELDON A. D. , BECK KATHY A. , ROWLAND P. H.
Published: April 2010

Five 3‐month‐old foals presenting with fever and respiratory disease were found to have pulmonary abscesses with patchy to diffuse alveolar and interstitial pneumonia on post‐mortem examination. All affected foals had evidence ofRhodococcus equiinfection and had few to abundantPneumocystis cariniicysts in the sections of affected lung. Of the 5 foals examined radiographically, 3 had a distinct reticulonodular (miliary) pattern which may aid in the ante‐mortem diagnosis ofP. cariniipneumonia (PCP). Leukocyte counts of foals with PCP were significantly greater than in the control group of foals with uncomplicated bacterial pneumonia. Foals with PCP tended to be more tachypnoeic than the control foals and 4 of the 5 PCP+ foals appeared dyspnoeic before death. The ante‐mortem recognition of PCP may be expedited by bronchoalveolar lavage and successful treatment of foals with PCP may require the administration of adequate levels of potentiated sulphonamides.
An immunohistological study of MHC Class II expression and T lymphocytes in the endometrium of the mare
Authors: WATSON ELAINE D. , DIXON C. E.
Published: April 2010

The distribution of T lymphocytes and of cells bearing MHC Class II antigens in the endometrium of the mare was studied using an avidin‐biotin‐peroxidase staining method. The cells within the endometrium which expressed MHC Class II were macrophages, lymphocytes, monocytes, dendritic cells, epithelial cells and endothelial cells. MHC Class II expression increased significantly (P<0.05) in the luminal epithelium and tended (P=0.0573) to increase in the subepithelial layers during oestrus. Numbers of T lymphocytes did not differ between oestrus and dioestrus. MHC Class II expression and T lymphocyte numbers were not significantly different in samples collected on Day 14 of dioestrus and on Day 14 of pregnancy. The presence of endometritis greatly increased MHC Class II expression and T lymphocyte numbers within the endometrium.
Muscle characteristics in Standardbreds of different ages and sexes
Authors: RONÉUS MERIKE
Published: April 2010

Biopsy samples were taken from the middle gluteal muscle in 107 healthy Standardbred horses. The horses were separated according to sex and divided into 4 age groups (1, 2, 3 and 4–6 years). The proportion of Type I fibres increased with age (from 16 to 20%), irrespective of sex. The proportions of Type IIA and IIB fibres varied with age and differed between stallions and mares. Type IIA fibres increased in mares from 37 to 47% and in stallions from 40 to 48% and Type IIB fibres decreased from 49 to 34% in mares, and from 43 to 30% in stallions. Mares and stallions did not differ in enzyme activities, which changed with age. The activity of citrate synthase increased from 30 to 62 mmol/kg/min and that of lactate dehydrogenase decreased from 1,930 to 1,565 mmol/kg/min. The relative area of each fibre type was measured in biopsy samples from 7 mares and 7 stallions aged 1 year and 7 mares and 11 stallions aged 4–6 years. The relative areas of Type IIA and IIB fibres changed with age and differed between sexes. The relative area of Type IIA fibres increased in mares from 30 to 35% and in stallions from 33 to 47% and that of Type IIB fibres decreased in mares from 63 to 54% and in stallions from 55 to 38% between the ages of 1 and 4–6 years. This study shows that age influences enzyme activities, the relative number of Type I fibres, the Type IIA/IIB fibre ratio and the relative areas of Type IIA and IIB fibres in the middle gluteal muscle of Standardbreds. It also shows that stallions have a higher Type IIA/IIB fibre ratio and a higher relative area of Type IIA fibres and a smaller relative area of Type IIB fibres compared with mares.
Effect of stabling on bronchoalveolar cells obtained from normal and COPD horses
Authors: TREMBLAY G. M. , FERLAND CLAUDINE , LAPOINTE J.‐M. , VRINS A. , LAVOIE J. P. , CORMIER YVON
Published: April 2010

Bronchoalveolar lavages (BAL) were performed before and after 3 weeks of housing in 5 horses suffering from COPD and 5 normal horses. In the two groups, the total number of cells recovered remained unchanged after stabling. The most common cell populations in BAL fluid of control animals were alveolar macrophages (46.4%) and lymphocytes (44.9%). The percentage of neutrophils increased after stabling from 8.7% to 27.6%. In COPD horses, lymphocytes predominated (40.7%) in animals at pasture with neutrophils increasing from 29.4% to 71.6% after stabling. After fractionation by Percoll density gradient, alveolar macrophages and neutrophils from normal and COPD horses had a similar density distribution. After stabling, these cells from normal horses were increased in the low density layers, while those from COPD horses were predominantly in the hyperdense layers. Therefore, BAL cells obtained from COPD animals at pasture and after stabling differ from those of control horses in the same environment, not only in their populations but also in their buoyant densities. These differences could be related to different states of cellular activation and perhaps be responsible for disease activity in the COPD horses.
Clinical and pathological features of thoracic neoplasia in the horse
Authors: MAIR T. S. , BROWN P. J.
Published: April 2010

Thirty‐eight horses with confirmed thoracic neoplasia included 28 (37.7%) with lymphosarcoma, 4 (10.5%) with metastatic renal cell carcinoma, 2 (5.3%) with primary lung carcinoma, 2 (5.3%) with secondary squamous cell carcinoma from the stomach, 1 (2.6%) with pleural mesothelioma, and 1 (2.6%) with malignant melanoma.

The major clinical features included weight loss, inappetence, dyspnoea and coughing, but in cases of lung metastases, they related more to the primary site of tumour formation. Haematological and serum biochemical abnormalities were non‐specific. Specific pre‐mortem diagnosis was made in 14 horses; this was most readily achieved when exfoliated neoplastic cells were present in pleural fluid.
Clinical syndrome and diagnosis of hyperkalaemic periodic paralysis in Quarter Horses
Authors: NAYLOR J. M. , JONES V. , BERRY S‐L.
Published: April 2010

Of the 16 horses studied, 14 belonged to a family previously shown to be susceptible to hyperkalaemic periodic paralysis (HPP), and 8 were shown to have HPP. Diagnosis of HPP by electromyographic detection of myotonic discharges or by oral administration of KCl to induce clinical signs and hyperkalaemia had similar reliability and gave the same result in 80% of cases. KCl had to be administered at doses up to 0.2 g/kg bodyweight to produce signs in some horses. KCl challenge testing was more time consuming than EMG and resulted in one fatality. Overall, electromyography and potassium challenge testing together gave the most accurate diagnosis. Horses were more likely to manifest signs of HPP if they were immature. There was no sex predisposition. The most frequent sign of HPP was muscle fasciculation. Other signs were sweating, muscle spasm, and weakness. Respiratory rate increased greatly during some attacks. Attacks of muscle fasciculation without hyperkalaemia were observed in 2 HPP‐affected horses. Affected horses had a greater frequency of spontaneous clinical abnormalities, due mainly to trailering problems, traumatic abrasions and episodes of continuous muscle fasciculation. Hyperkalaemia was confirmed in only one of these instances.
Responses of horses affected with chronic obstructive pulmonary disease to inhalation challenges with mould antigens
Authors: McGORUM B. C. , DIXON P. M. , HALLIWELL R. E. W.
Published: April 2010

Eight control and 8 asymptomatic COPD‐affected horses were given, on separate occasions, inhalation challenges with extracts ofMicropolyspora faeni, Aspergillus fumigatusandThermoactinomyces vulgaris. All horses were also given nebulised phosphate‐buffered saline (PBS) challenges and ‘;natural challenges’ (NCs), i.e. exposure to hay and straw, as control challenges. Responses were assessed by clinical, pulmonary mechanics, arterial blood gas tensions, arterial blood pH and bronchoalveolar lavage fluid cytological examinations.

PBS challenges had no effect on control or COPD‐affected horses, while NC induced COPD only in the COPD‐affected horses. Pulmonary disease, similar to naturally occurring COPD, was induced, only in the COPD‐affected horses, byM. faeniandA. fumigatuschallenges, thus implicating these organisms in the aetiology of equine COPD. The role ofT. vulgarisin the aetiology of equine COPD could not, however, be determined because theT. vulgarischallenges, in addition to inducing pulmonary disease in 4 COPD‐affected horses, induced pulmonary disease in 2 control horses which had been unaffected by NC.

The absence of pulmonary disease in control horses afterM. faeni, A. fumigatusand NC challenges suggests that equine COPD is a pulmonary hypersensitivity, rather than a non‐specific toxic response.
Clinical pharmacokinetics of amikacin in hypoxic premature foals
Authors: GREEN SHERRIL L. , CONLON P. D.
Published: April 2010

The pharmacokinetics of amikacin, administered iv at 7 mg/kg, every 8 h, were evaluated over the first 48 h of hospitalisation in 7 critically ill hypoxic premature foals and compared with those in 8 full‐term nonhypoxic critically ill neonatal foals. The pharmacokinetic data were used to calculate dosage schedules that would maintain the plasma amikacin concentrations in individual foals within a target range of ≥15 μg/ml but <30 μg/ml for peak values and ≤3 μg/ml for trough values. The results indicated a statistically significant increase in the amikacin serum half‐life (5.39 ± 3.46 h) and smaller elimination rate constant (0.17 ± 0.09 h−1) in premature foals. The pharmacokinetic derangements required increasing the dose to 8.5–10.5 mg/kg bwt in 6 of 7 premature foals and an increase in the dosage interval to 12–24 h in all 7 foals. Overall, the total dosage of amikacin was decreased in the hypoxic, premature foals so that target peaks and troughs could be maintained.

Our findings suggest that prematurity and hypoxia are variables related to a prolonged serum half‐life of amikacin in hypoxic, premature foals. Although there was no evidence of amikacin‐induced nephrotoxicity in any of these foals, daily monitoring and tailoring of the dose schedule to the individual foal are strongly advised.
Cardiovascular effects of thoracic compression in horses subjected to euthanasia
Authors: HUBBELL J. A. E. , MUIR W. W. , GAYNOR J. S.
Published: April 2010

Six horses scheduled for euthanasia were instrumented for the measurement of blood flow by thermodilution, pulmonary arterial, right atrial and arterial blood pressures and collection of arterial blood for pH and blood gas analysis. The horses were anaesthetised with intravenous (iv) thiamylal sodium (10 mg/kg) and placed in right lateral recumbency. After euthanasia with an overdose of pentobarbitone sodium (100 mg/kg, iv) and loss of the electrocardiogram and arterial pulse pressure, thoracic compression at rates of 40, 60 and 80 compressions/min was instituted. Thoracic compression was accomplished by an investigator who delivered a blow to the chest wall with his knee while dropping from a standing or crouching position. Compression rates of 40, 60 and 80/min produced blood flows of 5.65 ± 0.5, 6.33 ± 1.11 and 8.28 ± 2.16 litres/min, respectively. Compression rates of 80/min produced significantly (P<0.05) greater blood flows and mean arterial blood pressures than did slower rates. The blood flows produced by 80 thoracic compressions/min were approximately 50% of those reported for deeply anaesthetised horses and while not sufficient to sustain life might be used to prolong life in order to facilitate distribution of resuscitative drugs to vital tissues.
Characterisation of osseous bodies of the distal phalanx of foals
Authors: KANEPS A. J. , O'BRIEN T. R. , REDDEN R. F. , STOVER S. M. , POOL R. R.
Published: April 2010

The distal phalanx and metacarpal physis of both forelimbs of 32 Thoroughbred foals 3–32 weeks of age were radiographed to identify those limbs with osseous bodies at a palmar process (PP) of the distal phalanx. Osseous bodies (ossicles) were identified radiographically in 19% of the foals. Sixteen of the 32 foals were selected for microradiographic and histological evaluation: 6 foals with radiographic evidence of ossicles and 10 foals without. Fourteen ossicles of the PP were observed radiographically. Ossicles were either a triangular bone fragment at the palmar aspect of the distal angle of the PP, or an oblong bone fragment separated from P3 by a radiolucent line extending 1–3 cm from the incisure of the PP to the solar margin. One foal had radiographic evidence of bilateral distal metacarpal physitis.

Seventeen of 35 PPs examined microradiographically were considered normal, in that the dorsal and solar cortices were thin with trabecular bone orientated parallel to the cortical surfaces, and there was a depression in the dorsal cortical surface (i.e. parietal sulcus). Abnormal microradiographic findings in the other 18 PPs included a fracture line extending from the dorsal cortical surfaces and trabecular bridging of the fracture gap. The fracture line was often continuous with the parietal sulcus. Microradiographic evidence of a fracture was found in 75% of foals evaluated.

Normal histological findings in 16 PPs included thin dorsal and solar cortices with trabeculae orientated parallel to the cortical surfaces, parallel‐fibred dense connective tissue attachments of the deep digital flexor tendon to the solar cortical surface, and a neurovascular bundle associated with the parietal sulcus. Abnormal histological findings of the other 20 PPs included: a fracture line extending from the dorsal to solar cortical surfaces, trabecular bridging of the fracture gap, and fibrocartilage which was within the fracture gap and orientated parallel to the longitudinal axis of the gap. Histological findings consistent with a fracture were found in 69% of foals evaluated.

It was concluded that ossicles of the PP in foals 3–32 weeks of age are fractures, not all of which are visible radiographically.
The airway response of horses with recurrent airway obstruction (heaves) to aerosol administration of ipratropium bromide
Authors: ROBINSON N. E. , DERKSEN F. J. , BERNEY C. , GOOSSENS L.
Published: April 2010

The airway response to aerosol administration of the anticholinergic agent ipratropium bromide was determined in 8 horses with recurrent airway obstruction (heaves). The reversibility of airway obstruction was confirmed by measuring lung function before and during stabling; and by determining the response to atropine administration (0.02 mg/kg bwt intravenously). The dose‐response to ipratropium bromide was determined using a Williams square design experiment in which 25, 50 or 75 μg ipratropium bromide/ml (4 ml/100 kg bwt) or the same volume of vehicle was administered to each horse by nebulisation. Lung function was measured before and 1 and 4 h after nebulisation. Vehicle had no effect on lung function. Ipratropium decreased the maximal change in pleural pressure during tidal breathing (ΔPplmax) and pulmonary resistance (RL) and increased dynamic compliance (Cdyn). At the 1 h measurement period, the effect on RLand Cdynwas dose‐dependent. A separate experiment demonstrated that the duration of action of ipratropium was between 4 and 6 h.
Paravertebral thoracolumbar anaesthesia in 10 horses
Authors: MOON PAULA F. , SUTER C. M.
Published: April 2010

The caudal border of the last rib was used as a reliable point of orientation while performing paravertebral thoracolumbar anaesthesia (PTLA) on 10 horses undergoing standing flank laparotomy. The local anaesthetic in all horses was 2% lidocaine. The PTLA procedure was completed in 9.8±1.8 mins (mean ± sd). Sedation was provided by a combination of intravenous morphine with xylazine or detomidine. Overall analgesia, provided by the combination of PTLA and sedation, was rated as excellent in 2 horses and good in 6 horses. In the remaining 2 horses, overall analgesia was rated as fair because of incomplete analgesia at the ventral portion of the incision. Total time, from start of PTLA to end of surgery was 143.5±24.2 mins. Five horses responded mildly to suturing of the ventral portion of the incision. Apart from 1 horse which developed transient, unilateral hindlimb weakness intraoperatively, no other complications were noticed. We conclude that PTLA can easily be performed in the horse and, combined with systemic sedation, is an effective and safe method of providing analgesia for standing flank laparotomy.
In‐vitro susceptibility to antimicrobial drugs of bacterial isolates from horses in The Netherlands
Authors: ENSINK J. M. , VAN KLINGEREN B. , HOUWERS D. J. , KLEIN W. R. , VULTO A. G.
Published: April 2010

Minimum inhibitory concentrations (MICs) of 30 antimicrobial agents (including the hitherto unreported antimicrobial agents doxycycline, minocycline, vanomycin, 3 quinolones and 3 combinations of antimicrobial agents) for isolates ofSalmonellaspp. (20),Escherichia coli(17),Klebsiellaspp. (8),Proteusspp. (7),Pseudomonas aeruginosa(7),Actinobacillus equuli(5),Rhodococcus equi(4),Streptococcus zooepidemicus(23),Streptococcus equisimilis(6),Streptococcus equi(4), coagulase‐positiveStaphylococcusspp. (20) andTaylorella equigenitalis(19) were determined using the agar dilution method. All isolates were of equine origin.

MICs were compared with recommended MIC breakpoints. The results indicate that, for some of the pathogenic bacteria evaluated, susceptibility testing of isolates from the individual patient is essential to determine an appropriate antimicrobial treatment.
Measurement of 24‐h gastric pH using an indwelling pH electrode in horses unfed, fed and treated with ranitidine
Authors: MURRAY M. J. , SCHUSSER G. F.
Published: April 2010

A glass combined pH‐reference electrode was placed in the stomachs of 5 adult horses and pH was recorded every 6 mins for 24 h while (1) feed and all bedding materials were withheld for 24 h (unfed), (2) horses had free access to Timothy grass hay for 24 h (fed), and (3) horses had free access to Timothy grass hay and were treated with ranitidine, 6.6 mg/kg body weight, orally, every 8 h for 48 h (fed + ranitidine). There was a significant (P= 0.007) difference in median 24‐h gastric pH amongst the 3 protocols, the value being 3.1 in fed horses and 1.55 in unfed horses (P= 0.05) and 4.6 in fed + ranitidine horses (P= 0.05 compared with fed horses).

The percentage of pH readings <2.0 was significantly greater (P= 0.05) in unfed (76%) than in fed (30%) horses, and in fed horses than in fed + ranitidine (9%) horses. The percentage of readings >2.0, 3.0, 4.0, 5.0 and 6.0 were each significantly (P= 0.05) greater in fed + ranitidine horses than in fed horses, and in fed than in unfed horses. There was no difference (P= 0.13) between median gastric pH values from different times of day in unfed horses (00:00 to 06:00 h, 1.5; 06:00 to 12:00 h, 1.6; 12:00 to 18:00 h, 1.7; and 18:00 to 24:00 h, 1.5).

We conclude that gastric acidity is greatest when horses do not have access to feed material and that ranitidine effectively suppresses gastric acidity in horses under conditions of free access to hay.
Retrospective analysis of the results of 151 exploratory laparotomies in horses with gastrointestinal disease
Authors: PHILLIPS T. J. , WALMSLEY J. P.
Published: April 2010

Of 149 horses that underwent 151 exploratory laparotomies for gastrointestinal disorders from September 1987 to May 1991, 107 (72%) were discharged from the hospital: 100 (66%) survived for >7 months, 94 of which returned to their intended use. Survival rate (64/80) for horses with caecum/large colon obstruction was significantly (P=0.003) higher than for horses with small intestinal obstruction (33/64). Prolonged surgery was associated with significantly (P<0.001) lower survival rates than short surgical time. In the large intestine, survival rate (15/29) for strangulated obstructions was significantly (P<.0.001) lower than for simple obstructions (52/58). Generalised septic peritonitis (9 horses) and bowel obstruction associated with adhesions (8 horses) were the most frequent fatal post‐operative complications. The rate (6/44) of post‐operative adhesions after small intestinal obstruction was significantly (P=0.006) higher than that (2/68) following large intestinal obstruction. The rate (8/55) of post‐operative adhesion formation in horses that required enterotomy/enterectomy was significantly (P=0.003) higher than that (0/57) in horses that did not require gut wall incisions. Incisional suppuration developed in 42 horses and occurred with a significantly (P=0.028) higher rate (32/72) after caecum/large colon lesions than after obstruction at other sites, (10/42) but was not associated with known contamination at the time of surgery (P=0.806).
Diagnosis and prediction of cervical vertebral malformation in Thoroughbred foals based on semi‐quantitative radiographic indicators
Authors: MAYHEW I. G. , DONAWICK W. J. , GREEN S. L. , GALLIGAN D. T. , STANLEY E. K. , OSBORNE J.
Published: April 2010

Over a period of 5 years on a central Kentucky Thoroughbred stud farm 132 foals were evaluated for the presence of cervical vertebral malformation (CVM). Lateral cervical vertebral radiographs were obtained on 70 standing foals. These radiographs were evaluated semi‐quantitatively and scored numerically for the presence of stenosis of the vertebral canal, enlarged physeal growth plates, caudal extension of the dorsal border of the orifice of the vertebral canal, angular fixation, delayed ossification of bone and degenerative joint disease. From these scores a total CVM score was given for each set of radiographs. All foals were repeatedly examined for clinical signs of neurological disease. Foals with no clinical signs of CVM had maximal total CVM scores (mean ± sd) of 5.7 ± 2.8 and foals affected with CVM had maximal total CVM scores of 17.0 ± 2.8. Determination of the total CVM score was non‐invasive, inexpensive and a very accurate procedure for predicting and diagnosing the presence of CVM in Thoroughbred foals up to 1 year of age.
Correlation of racing performance with blood lactate and heart rate after exercise in Thoroughbred horses
Authors: EVANS D. L. , HARRIS R. C. , SNOW D. H.
Published: April 2010

At 2 and 5 mins after an 800‐m gallop, venous blood was collected from 26 Thoroughbred racehorses for measurement of blood lactate concentration, packed cell volume (PCV) and haemoglobin concentration. In addition, 14 racehorses were given a strenuous submaximal treadmill exercise test. Heart rates during and after exercise at 10 m/sec on a treadmill inclined at 5° were recorded. Blood samples at 2 and 5 mins after exercise were used to measure PCV, blood and plasma lactate and ammonia concentrations. Results of each exercise test were compared with the retrospective performance of horses in races, using Timeform ratings. The results of the field tests were also compared with the performance of each horse in a race 2 days later.

There were no significant correlations between any of the measurements taken after the Field test and either subsequent race performance or Timeform rating. Heart rate 4 mins after treadmill exercise was significantly correlated with Timeform rating (r =−0.565, P<0.05). Blood and plasma lactate concentrations 2 and 5 mins after treadmill exercise were all significantly correlated with Timeform. The highest correlations were with blood lactate concentrations 2 and 5 mins after exercise (r =−0.68, P < 0.01). There were no significant correlations between Timeform and heart rate during exercise at 10 m/sec, heart rates at 1, 3 and 5 mins after exercise, PCV and plasma ammonia at 2 and 5 mins, or the differences between lactate concentration in plasma or blood at 2 and 5 mins after exercise. It is concluded that the quality of Thoroughbred race performance is significantly correlated with the blood lactate concentration after strenuous submaximal treadmill exercise.
Immunocytochemical and lectin histochemical study of neuronal lesions in autonomic ganglia of horses with grass sickness
Authors: GRIFFITHS I. R. , KYRIAKIDES E. , SMITH S. , HOWIE F. , DEARY A. W.
Published: April 2010

Equine grass sickness (EGS) is a primary dysautonomia characterised pathologically by lesions in autonomic ganglia, enteric plexi and specific nuclei in the CNS. Immunocytochemistry and lectin histochemistry of the autonomic ganglia were used to determine whether abnormalities can be detected in specific proteins or cellular organelles. EGS ganglia contained a mixture of morphologically normal and abnormal neurons, the former appearing identical to cells from control animals. Affected cells showed marked disturbances in neurofilament (NF) proteins and β‐tubulin, major components of the cytoskeleton; in most neurons immunoreactivity was reduced or absent while the distribution was altered in the remainder. Staining for neuron‐specific enolase, a pan‐neuronal marker, was severely reduced or absent, as was reactivity for the catecholaminergic enzyme tyrosine hydroxylase. However, affected neurons showed a marked increase in dopamine‐β‐hydroxylase (DβH), another enzyme associated with noradrenaline synthesis. Wheat germ agglutinin and Griffonia simplicifolia B4 lectin histochemistry was used to label membranes of the Golgi apparatus, which stained as discrete curvilinear perinuclear profiles. All affected neurons showed abnormalities with either complete loss of reaction or amorphous centrally located lectin staining.

The results indicate perturbation in a wide variety of cytoplasmic and cytoskeletal proteins. In the majority of instances there is a decrease in stainable protein; the increase in DβH may indicate a failure to be transported down the axon with resultant accumulation in the perikaryon. Loss of a recognisable Golgi structure appears to be an early event in the neuropathology of EGS.
A study of 118 cases of navicular disease: radiological features
Authors: WRIGHT I. M.
Published: April 2010

Dorsoproximal‐palmarodistal oblique, lateromedial and palmaroproximal‐palmarodistal oblique radiographic projections were used with standard techniques to examine 118 horses with clinical signs of navicular disease. All radiological features which have previously been reported as significant changes in the navicular bones of horses with navicular disease were recorded. Comparisons were made between these features in lame limbs and sound limbs in unilaterally lame horses and most lame limbs and least lame limbs in bilateral but asymmetrically lame animals. Their relationship to the degree of lameness was also analysed. No relationships were identified between the characteristics of distal border synovial invaginations, flattening and/or thinning of the flexor cortex and limb distribution or severity of lameness. Defects in the flexor cortex, proximal border remodelling, medullary trabecular disruption and medullary sclerosis appeared to be related to limb affliction and severity of lameness while proximal border enthesophytes, and poor flexor corticomedullary demarcation presented evidence of a relationship to the grade of lameness. Poor flexor corticomedullary demarcation and fragmentation of the distal border were related to the severity of lameness in bilateral but asymmetrically affected horses. The presence of peri‐articular osteophytes and mineralisation of the flexor digitorum profundus were too infrequently recognised to permit meaningful data evaluation.
Age‐related characteristics of gastric squamous epithelial mucosa in foals
Authors: MURRAY M. J. , MAHAFFEY E. A.
Published: April 2010

Specimens of grossly normal gastric stratified squamous epithelial mucosa adjacent to the margo plicatus on the right side and along the greater curvature were obtained from 7 foetuses, 10 term foals and 12 foals 2–35 days old. Gastric squamous epithelium from the foetuses changed markedly during gestation. At 150–270 days, the epithelium was 8–10 cells thick, with a single layer of basal cells. Epithelial cells were polyhedral and had abundant clear or slightly stained cytoplasm. In the 300‐day foetus the basal layer was thicker, epithelial cells were polyhedral, and there was a flattened 1 cell‐thick layer superficially. In the 335‐day foetus, the epithelial cells were flat and there was a superficial layer of keratinised cells, 1–2 cells thick. In term foals, the gastric epithelium consisted of 10–12 cell layers, with 4–5 thin layers of surface keratin. Epithelial projections (papillae) were either absent or not pronounced. The gastric epithelium became thicker with increasing age, including increased epithelial cell layers, thickening of the keratinised layers, and more pronounced papillae. Desquamation was observed in the keratinised layers of gastric squamous epithelium from foals ≥2 days of age.
Histological findings in corneal stromal abscesses of 11 horses: correlation with cultures and cytology
Authors: HAMILTON HOLLY L. , McLAUGHLIN SUSAN A. , WHITLEY ELIZABETH M. , GILGER B. C. , WHITLEY R. D.
Published: April 2010

Histopathology was compared to culture results and cytology from horses with corneal stromal abscess at the Auburn University and the Ohio State University Veterinary Teaching Hospitals. Significant bacteria were not isolated in culture or seen on histopathology in any of the horses. Although most bacteria infecting equine corneas can be isolated with blood and MacConkey's agars, failure to detect bacterial growth may not rule out infection because anaerobic or intracellular bacteria would not be isolated. The inability to visualise bacterial organisms on histological sections did not rule out their presence in the tissue, because there is often destruction of bacteria by neutrophils, macrophages and antibiotic therapy greatly reducing their numbers. Fungal keratitis was diagnosed by histopathology in 4 of 11 eyes (36%) and keratitis with no aetiological agent in 7 of 11 eyes (64%). Nine of 11 horses (82%) had a prominent neutrophilic stromal infiltrate and 2 (18%) had a predominately pyogranulomatous reaction. Two of the 4 lesions that showed histological evidence of fungal infection were positive for identifiable fungi on culture and cytology. Fungal cultures of the other 2 cases with histological evidence of mycotic keratitis were negative or grew unidentifiable fungi which were considered pathogenic because, on histopathological sections, fungal hyphae were found deep in the corneal stroma surrounded by an inflammatory reaction. In 3 of 6 cases where fungi were recovered on culture, they were considered contaminants based on lack of evidence of organisms in histopathological sections. Histopathology and the use of special stains were important in the interpretation of culture and cytology results.
Distribution of Equid herpesvirus‐1 (EHV‐1) in the respiratory tract of ponies: implications for vaccination strategies
Authors: KYDD JULIA H. , SMITH K. C. , HANNANT D. , LIVESAY GEORGIA J. , MUMFORD JENNIFER A.
Published: April 2010

Twelve adult ponies and 2 conventional foals were exposed to 106.6TCID50of Equid herpesvirus‐1 (EHV‐1), strain Ab4 and samples of respiratory tract tissues were recovered. Infectious virus in tissue homogenates was detected using susceptible cell monolayers and expression of viral antigens was monitored using indirect immunoperoxidase histochemistry of paraffin sections. The results illustrated the rapid dissemination of EHV‐1 throughout the respiratory tract, with early replication in the lungs one day after exposure. Endothelial cell infection was prominent in all areas of the nasopharynx by Day 4 emphasising the role of endotheliotropism and viraemia in dissemination of this virus to sites of secondary replication. Clinical disease in the adult ponies was mild.
A survey of exercise‐induced pulmonary haemorrhage in Quebec Standardbred racehorses
Authors: LAPOINTE J. ‐M. , VRINS A. , McCARVILL E.
Published: April 2010

Sixty Standardbred horses, aged 3 to 10 years, were examined endoscopically for exercise‐induced pulmonary haemorrhage (EIPH) 1 h after racing, on at least 3 occasions. Racing time, finishing position and post exercise venous lactate concentrations were also recorded. Horses positive for tracheal blood on endoscopy were classified as having eithergrade 1EIPH (one or a few spots of blood in the trachea), orgrade 2(stream of blood). Air temperature, relative humidity and air pollutant levels were recorded on each examination day.

Of the 60 horses, 52 (87%) were EIPH‐positive on at least one evaluation out of 3 and 40 of the 52 (77%) showedgrade 2EIPH on at least one occasion. Of the 52 EIPH‐positive horses, 52% bled 3 times out of 3, 21% 2 out of 3 and 27% once. When only the first examination was considered, 37 of the 60 horses (62%) were EIPH‐positive. There was no significant relation detected between either presence or frequency of EIPH and age, sex, or gait. Horses that showedgrade 2EIPH bled significantly (P = <0.001) more frequently (mean: 83% of examinations) than horses having shown no more thangrade 1EIPH (47% of examinations).

No significant differences could be detected between EIPH‐positive and EIPH‐negative races in the average racing times, finishing positions and blood lactate concentrations of the 29 horses which showed intermittent EIPH. The proportion of horses showing EIPH on each day where at least 5 horses were examined was correlated with air temperature, relative humidity, and the levels of several air pollutants on those days. There was a significant negative correlation between air temperature and proportion of EIPH‐positive horses (P = 0.0007, r2= 0.39). No significant relations were detected with relative humidity or air pollutant levels.
Experimentally‐induced synovitis as a model for acute synovitis in the horse
Authors: PALMER JAN L. , BERTONE ALICIA L.
Published: April 2010

The use of extremely small dosages of intra‐articularE. colilipopolysaccharide (LPS) endotoxin can create a model of synovitis that mimics acute synovitis in horses. Dosages of 5000 ng, 25 ng, 0.5 ng, 0.25 ng, 0.17 ng and 0.125 ng per joint were injected into various joints of a total of 6 horses. The dose response of LPS on clinical signs and synovial fluid parameters was evaluated at baseline and 12, 24, 36 and 48 h after LPS injection. Peripheral venous blood analysis was performed at baseline and at 0, 4, and 12 h after LPS injection. Dosages greater than 0.5 ng/joint resulted in clinical signs of endotoxaemia including fever, depression, inappetence and non‐weightbearing lameness. Although the total peripheral venous leucocyte count was not decreased at any dosage, the 5000 ng/joint dosage of LPS altered venous leucocyte differential resulting in an increase in the number of segmented and band neutrophils with a concomitant decrease in lymphocytes. Synovial fluid total nucleated cell count (TNC) and total protein (TP) was linearly responsive to increases in intra‐articular LPS dosages up to the 0.5 ng/joint dose. At dosages of LPS > 0.5 ng, synovial fluid mean ± s.e.m. TNC and TP were 122.0 ± 27 × 109cells/l and 59.3 ± 1.7 g/l respectively, at 12 h after injection. This may represent the maximal response of the joint to increased concentrations of LPS endotoxin over 0.5 ng/joint. The 0.125 ng dosage of LPS endotoxin resulted in a synovial fluid mean ± s.e.m. TNC and TP of 31.5 ± 4.3 × 109cells/l and 40.2 ± 2.3 g/l respectively, at 12 h after injection. At the 0.125 ng/joint dosage, horses exhibited mild to moderate effusion and warmth of the injected joint, mild resistance to palpation and agrade 2lameness. Horses at this dosage continued to bear weight on the injected limb and eat throughout the 48 h study period. By the end of the 48 h study period joint effusion was decreased and lameness was subsiding.

In a subsequent study, the response to repeated LPS at the 0.125 ng dosage was evaluated to determine the ability of the joint to respond and maintain the synovitis. Clinical and synovial fluid parameters were evaluated at baseline and 6, 12, 18, 24, 36, 48, 60, 96, 108, 144, and 156 h after intra‐articular LPS at the 0.125 ng dosage. LPS injections were repeated immediately after the 48, 96 and 144 h arthrocentesis periods in an effort to maintain the synovitis for a period of one week. Synovial fluid parameters and clinical signs of lameness and joint effusion began to wane between 36 and 48 h after each repeated injection. However, the synovial membrane was capable of responding and maintaining the clinical and synovial fluid signs of synovitis over the study period with repeated LPS injections at the same 0.125 ng/joint dosage.
Epidemiology of equineCryptosporidiumandGiardiainfections
Authors: XIAO LIHUA , HERD R. P.
Published: April 2010

Prevalence and infection patterns ofCryptosporidiumandGiardiainfections in horses were studied by a direct immunofluorescence staining method. Faecal examinations of 222 horses of different age groups revealedCryptosporidiuminfection rates of 15–31% in 66 foals surveyed in central Ohio, southern Ohio and central Kentucky, USA. Only 1 of 39 weanlings, 0 of 46 yearlings, and 0 of 71 mares were positive.Giardiainfection was found in all age groups, although the infection rates for foals were higher (17–35%). Chronological study of infection in 35 foals showed that foals started to excreteCryptosporidiumoocysts between 4 and 19 weeks andGiardiacysts between 2 and 22 weeks of age. The cumulative infection rates ofCryptosporidiumandGiardiain foals were each 71%. Some foals were concurrently infected with both parasites and excretion of oocysts or cysts was intermittent and long‐lasting. The longest duration of excretion was 14 weeks forCryptosporidiumand 16 weeks forGiardia.Excretion ofCryptosporidiumoocysts stopped before weaning, while excretion ofGiardiacysts continued thereafter.

Infected foals were considered the major source ofCryptosporidiuminfection in foals, whereas infected mares were deemed the major source ofGiardiainfection in foals. The high infection rate ofGiardiain nursing mares suggested a periparturient relaxation of immunity. The results indicated thatCryptosporidiumandGiardiainfections are common in horses.
Quantitative analysis of cyanogen bromide‐cleaved peptides for the assessment of Type I: Type II collagen ratios in equine articular repair tissue
Authors: BARR A. R. S. , DUANCE V. C. , WOTTON S. F. , WATERMAN A. E. , HOLT P. E.
Published: April 2010

Cyanogen bromide was used to solubilise and specifically fragment purified equine Type I and II collagen and equine articular surface repair tissue. The resultant peptides were separated by sodium dodecyl sulphate‐polyacrylamide gel electrophoresis and quantified by densitometric scanning. Measurement of the relative amounts of the peptides α2(I) CB3, 5 and α1(II)CB10 provided an accurate method of establishing the ratio of Type I to Type II collagen in mixtures of purified equine collagens. The method was sensitive to 6% Type II collagen when the band areas were corrected for peptide molecular weight and the number of chains in the parent tropocollagen molecule which contain that particular peptide. Use of this technique showed that repair tissue in full thickness osteochondral defects in the dorsodistal margins of the intermediate carpal bones of ponies did not contain detectable amounts of Type II collagen 11 weeks after defect induction.