bluuebunny/crossref_metadata_2025 huggingface dataset:
Reduced efficacy of anthelmintics in young compared with adult horses
Authors: HERD R. P. , GABEL A. A.
Published: April 2010

Studies on a Thoroughbred breeding farm in Ohio from 1982 to 1988 demonstrated the value of three anthelmintic pastes (ivermectin, oxibendazole, pyrantel pamoate) in controlling benzimidazole resistant cyathostomes (small strongyles) in adult horses. However, a comparison of drug efficacy in suppressing faecal egg counts for the full period between treatments showed a significant reduction in efficacy of all drugs in yearling horses compared with adults. Mean faecal egg counts of adult horses were generally kept below 100 eggs per gram (epg) of faeces when using oxibendazole or pyrantel pamoate at four to five week intervals and ivermectin at eight week intervals. By contrast, mean counts of young horses rose as high as 655 epg (oxibendazole), 729 epg (pyrantel pamoate) and 852 epg (ivermectin) within the same time period after treatment. Individual counts of treated yearlings sometimes exceeded 3,000 epg. Three distinct mechanisms appeared to be involved in the poor results in young horses. These were 1) anthelmintic refuge, 2) anthelmintic resistance, and 3) anthelmintic avoidance.
A tracheoscopic technique for obtaining uncontaminated lower airway secretions for bacterial culture in the horse
Authors: DARIEN B. J. , BROWN C. M. , WALKER R. D. , WILLIAMS M. A. , DERKSEN F. J.
Published: April 2010

Transtracheal aspirate (TTA) aerobic microbiology culture results from 30 ponies were compared to protected catheter brush (PCB) culture results obtained from the same ponies. The PCB procedure resulted in significantly fewer (P<0.05) isolates than those obtained by the TTA procedure and the PCB procedure resulted in significantly more samples with no bacteria growth than the TTA procedure. To address the possibility that the volume of tracheobronchial secretion obtained by PCB was insufficient as a microbiological sample, a sterile, double‐sheathed, protected aspiration catheter (PAC) was developed. Comparisons were made between TTA and PAC aerobic microbiology culture results from 18 pneumonic foals and weanlings. There were no significant differences between the PAC and TTA procedures with respect to the number of bacteria isolates. It was concluded that the PAC technique may be used as an alternative to TTA for isolation of equine pulmonary bacteria and may be the preferred procedure because of the reduced risk of complications associated with the TTA.
Variation in conformation of Swedish Warmblood horses and conformational characteristics of élite sport horses
Authors: HOLMSTRÖM M. , MAGNUSSON L.‐E. , PHILIPSSON J.
Published: April 2010

The variation in conformation of 356 Swedish Warmblood horses is described, using a quantitative method of measuring horses. Thirty‐three of the horses were élite dressage horses, 28 were élite showjumpers, 100 were riding school horses and 195 were unselected four‐year‐olds. Most horses had a long body form. The average height at the withers was 163.4 cm. Sixty per cent of the horses had a bench knee conformation, 50 per cent had a toe‐in conformation of the forelimbs and 80 per cent had outwardly rotated hind limbs. The majority of these deviations were mild or moderate. Conformation was influenced by sex and age. Mares were smaller and had longer bodies and shorter limbs. The élite dressage horses and showjumpers had larger hock angles and more sloping scapulas than other horses. The showjumpers also had smaller fetlock angles in the front limbs. It is suggested that the larger hock angles among the elite horses may be because hocks with small angles are more prone to injury, and because small hock angles may negatively influence the ability to attain the degree of collection necessary for good performance in advanced classes.
Plasma theophylline concentration and lung function in ponies with recurrent obstructive lung disease
Authors: McKIERNAN B. C. , KORITZ G. D. , SCOTT JACQUELINE S. , BERNEY CATHY , ROBINSON N. E.
Published: April 2010

Six ponies with recurrent obstructive lung disease were studied during two separate 60 min periods while receiving constant equal volume infusions of either aminophylline or sterile water. Dynamic lung compliance, pulmonary resistance, respiratory rate, tidal volume, blood gas tensions and heart rate were measured. Plasma samples were obtained for determination of theophylline concentrations before, and at 10 min intervals during, the infusion period. Excitability was assessed subjectively at these same time periods. The plasma theophylline concentrations in ponies were well predicted by a previously published model of theophylline pharmacokinetics in the horse. Sterile water had no effect on lung function. Aminophylline produced significant changes in lung function compared to baseline values, including a decrease in resistance at 30 min when the mean plasma theophylline concentration was 59 ± 14 μmol/litre and an increase in compliance at 60 mins at a mean plasma theophylline concentration of 102 ± 23 μmol/litre. Excitement was noted between 40 and 50 mins in all ponies (mean plasma theophylline concentration 74 ± 20 and 84 ±24 μmol/litre, respectively). Heart rate increased at 50 mins. The therapeutic range for intravenous (iv) theophylline concentration in ‘heavey’ ponies therefore appears to be between 59 and 84 μmol/litre when aminophylline is administered iv. Below 59 μmol/litre there was no consistent bronchodilator activity and above 84 μmol/litre excitement and tachycardia limited the usefulness of the drug.
Specific immunotherapy in the treatment ofCulicoideshypersensitive horses: A double‐blind study
Authors: BARBET JOY L. , BEVIER DIANE , GREINER E. C.
Published: April 2010

Fourteen privately owned horses completed a six month, controlled, double‐blind trial to assess the efficacy of immunotherapy using an aqueous extract of whole, unfedCulicoides variipennisin the treatment ofCulicoideshypersensitivity. Selected horses had a history of a seasonal, pruritic dermatitis, clinical signs and distribution compatible withCulicoideshypersensitivity, failed to improve in response to ivermectin therapy, and reacted to several dilutions ofCulicoidesextracts without significant reactivity to other possible allergens including insects, moulds and feeds. One horse from the control group (n=8) and one from the test group (n=6) improved. Statistically, there was no significant difference between horses onCulicoidesantigen and control horses. In each group, four owners thought that their horses had improved.
Naloxone‐induced abdominal distress in the horse
Authors: KAMERLING S. G. , HAMRA JENA G. , BAGWELL CLEO A.
Published: April 2010

Endogenous opioid peptides have been implicated in the regulation of pain perception, behaviour, gastrointestinal activity and other physiological responses. However, the functional role of these peptides in the horse has yet to be elucidated. The opioid antagonist, naloxone, is often administered to infer endogenous opioid effects. In the present study, naloxone (0.75 mg/kg bodyweight) was administered to eight Thoroughbred racehorses and a number of behavioural and autonomic responses were measured. Naloxone produced rapid onset diarrhoea, restlessness, abdominal checking, tachycardia, tachypnoea, paradoxical yawning and diaphoresis. These responses described an acute abdominal distress syndrome similar to spasmodic colic. Results from this study suggest that, in the horse, endogenous opioids: 1) influence behaviour, 2) modify intestinal activity and sensation, and 3) if perturbed, may be involved in pathophysiology of colic.
The excretion of theobromine in Thoroughbred racehorses after feeding compounded cubes containing cocoa husk ‐establishment of a threshold value in horse urine
Authors: HAYWOOD P. E. , TEALE P. , MOSS M. S.
Published: April 2010

Thoroughbred geldings were fed racehorse cubes containing a predetermined concentration of theobromine in the form of cocoa husk. They were offered 7 kg of cubes per day, divided between morning and evening feed, and food consumption was monitored. Urinary concentrations of theobromine were determined following the consumption of cubes containing 11.5, 6.6, 2.0 and 1.2 mg per kg of theobromine, to verify whether or not such concentrations would produce positive urine tests. Pre‐dose urine samples were collected to verify the absence of theobromine before each experiment. It became apparent from the results of the first three administrations that the limit of detection of theobromine, using such procedures, would be reached at a feed level of about 1 mg per kg theobromine. Therefore the final administration, using cubes containing 1.2 mg per kg theobromine, was singled out for additional analytical work and quantitative procedures were developed to measure urinary concentrations of theobromine. It was anticipated that the results would form a basis for discussions relating to the establishment of a threshold value for theobromine in horse urine. The Stewards of the Jockey Club subsequently gave notice that they had established a threshold level for theobromine in urine of 2 μg/ml.
The stress response to anaesthesia in ponies: barbiturate anaesthesia
Authors: TAYLOR POLLY M.
Published: April 2010

Information on the equine stress response to anaesthesia and surgery is sparse but offers a promising approach to elucidating the high anaesthetic risk in this species. Previous work has shown that halothane anaesthesia induces substantial metabolic and endocrine changes. This paper reports the effects of barbiturate anaesthesia. Anaesthesia was induced with thiopentone in six ponies and no further agents were given. They stood within 30 mins. On another occasion, these animals, and three further ponies, were anaesthetised with pentobarbitone and anaesthesia was maintained for 2 h. No surgery was performed on either occasion. Plasma concentrations of glucose, lactate, non esterified fatty acids, cortisol, insulin, catecholamines and adrenocorticotrophic hormone were measured at the same time intervals in both groups before, during and after anaesthesia. There were no significant changes in hormones or metabolites during either period of anaesthesia and normotension was maintained. This was in marked contrast to the substantial stress response and hypotension under halothane anaesthesia in the same ponies. These results suggest that barbiturates may induce less of a stress response than halothane in horses. Recovery after 2 h of pentobarbitone anaesthesia was poor, precluding its clinical use. The need for a non‐cumulative intravenous agent or a non‐hypotensive volatile agent for use in equine anaesthesia is discussed.
Metabolic and hormonal changes associated with arthroscopic surgery in the horse
Authors: ROBERTSON SHEILAH A. , STEELE CYNTHIA J. , CHEN CHAO‐LING
Published: April 2010

The effect of general anaesthesia and arthroscopic surgery on blood glucose and lactate, plasma non‐esterified fatty acids, insulin, beta‐endorphin and cortisol was investigated in seven horses. Animals were premedicated with xylazine and anaesthesia was induced with guaifenesin and sodium thiamylal and maintained with halothane vaporised in oxygen. Blood samples were collected in the pre‐, intra‐ and post operative period. Induction of anaesthesia was associated with a transient hyperglycaemia and a significant rise in plasma insulin levels. Plasma insulin values fell during surgery but showed a significant increase post operatively. Surgery stimulated a small but significant rise in plasma beta‐endorphin and cortisol values but these had returned to baseline values in the early post operative period. No changes in blood lactate were recorded.
Effect of low‐dose butorphanol on halothane minimum alveolar concentration in ponies
Authors: MATTHEWS NORA S. , LINDSAY S. L.
Published: April 2010

Minimum alveolar concentration (MAC) for halothane was measured before and after administration of intravenous butorphanol (0.022 and 0.044 mg/kg in bodyweight in nine yearling Shetland ponies. Arterial blood pressure, heart rate, respiratory rate, expired CO2and rectal temperature was also measured. Even though mean MAC values decreased 10 and 9 per cent after the low and high doses respectively, they were not statistically different from those measured prior to butorphanol. Halothane MAC values increased after butorphanol in two ponies, both animals increasing locomotor activity and demonstrating apparent central nervous system stimulation. No significant differences were seen in any variable measured after butorphanol administration.
A scanning electron microscopic study of the equine upper respiratory tract
Authors: PIRIE MYRTLE , PIRIE H. M. , WRIGHT N. G.
Published: April 2010

The surface features of the upper respiratory tract of 20 clinically normal horses of various ages and types were studied with scanning electron microscopy. In the rostral part of the nasal cavity, there was a wide zone of non‐ciliated epithelium whereas, caudally, the surface was well ciliated. This latter type of epithelium extended into the nasopharynx and guttural pouches although scattered areas of non‐ciliated microvillous cells were also found.
An ultrastructural study of the equine lower respiratory tract
Authors: PIRIE MYRTLE , PIRIE H. M. , CRANSTON SHEILA , WRIGHT N. G.
Published: April 2010

The surface features of the lower respiratory tract of 20 clinically normal horses of different ages and types were studied with scanning electron microscopy. Parallel light microscopical and transmission electron microscopical studies were also carried out. The ciliary carpet was virtually complete from the trachea to the lobar bronchi. In small bronchi, ciliation was less complete allowing numerous non‐ciliated mucous cells to become obvious. The terminal bronchioles, populated mainly by non‐ciliated bronchiolar epithelial cells, had an abrupt junction with alveolar ducts. Interalveolar pores were common particularly in older horses.
Ultrastructural findings in horses with chronic obstructive pulmonary disease (COPD) II: pathomorphological changes of the terminal airways and the alveolar region
Authors: KAUP F.‐J. , DROMMER W. , DAMSCH S. , DEEGEN E.
Published: April 2010

Extensive light and electron microscope studies (transmission and scanning electron microscopy) of the bronchioles and alveolar region, in 28 horses suffering chronic obstructive pulmonary disease (COPD) and eight control horses, revealed good correlation between clinical severity and morphological changes. In the bronchiolar epithelium the non‐ciliated bronchiolar epithelial (Clara) cells, in particular, showed ultrastructural alterations and, even in the mild stages of disease, these presented degenerative changes and lack of differentiation. Together with loss of granulation in the Clara cells and metaplasia of the goblet cells, cells were seen with unusual intracytoplasmic lamellar inclusion, the number of which increased sharply with clinical severity. The focal changes in the alveolar region were necrosis of type I epithelial cells, alveolar fibrosis of varying degrees with type II epithelial transformation and emphysema or hyperinflation, with an increase in Kohn's pores. Some horse also showed morphological signs of interference with the surfactant system, in the form of marked cysts with lamellar structure. The alveolar changes were mostly in the peribronchiolar region and were, therefore, interpreted as reactive processes. No conclusions as to the aetiology of equine COPD can be derived from these morphological investigations.
Cardiopulmonary effects of xylazine sedation in the foal
Authors: CARTER S. W. , ROBERTSON SHEILAH A. , STEEL CYNTHIA J. , JOURDENAIS D. A.
Published: April 2010

Six healthy foals underwent instrumentation for measurement of the cardiopulmonary effects of sedation with 1.1 mg/kg bodyweight xylazine hydrochloride given intravenously. Responses to xylazine in foals at 10 and 28 days of age were not significantly different. Foals became sedate and markedly ataxic, and four of the six foals became recumbent. Heart rate decreased significantly but no arrhythmias were detected. Arterial blood pressure increased initially and then fell significantly below pre‐injection values. Changes in respiratory airflow, upper airway obstruction and respiratory noise were noted in the initial 20 mins of sedation, after which respiratory rate fell, tidal volume increased, and minute volume decreased gradually. Arterial blood gas tensions and pH did not change significantly during the 120 mins following xylazine administration. Control studies showed no significant changes. All foals recovered uneventfully.
Anatomical validation of two‐dimensional echocardiography in the horse
Authors: VÖRÖS K. , HOLMES J. R. , GIBBS CHRISTINE
Published: April 2010

This study was performed on 15 horses to validate the cardiac anatomy as imaged with two dimensional echocardiography (2DE) and to determine the accuracy of intracardiac measurements. 2DE images were recorded in five horses in life with a Diasonics DRF100 ultrasound system and a 3.5 MHz transducer in different tomographic planes. After slaughter, the hearts were fixed in 10 per cent formalin. To comparein vivoandin vitroresults, the specimens were suspended in a water‐filled tank and 2DE images were made using the same transducer positions as in life.In vitro2DE and autopsy measurements of the same planes and parameters were also taken on a further 10 hearts, and the results were statistically compared. Thein vivo2DE images corresponded well with bothin vitro2DE recordings and anatomical sections. Repeatable imaging of each tomographic plane was possible on the post mortem hearts using intracardiac reference points. Comparison of parameters measured duringin vitro2DE and autopsy demonstrated a significant correlation between all 2DE and autopsy data (r: 0.879 to 0.926; P<0.001). Repeated 2DE measurements of each parameter showed a good reproducibility with coefficients of variation (CV%) varying between 4.6 to 10.6 per cent. The results suggest that 2DE is a reliable method for accurate anatomical evaluation of the equine heart and show the potential application of quantitative two dimensional echocardiography in the living horse.
Scintigraphic evaluation of digital circulation during the developmental and acute phases of equine laminitis
Authors: TROUT D. R. , HORNOF W. J. , LINFORD R. L. , O'BRIEN T. R.
Published: April 2010

Scintigraphy was used to evaluate digital circulation at 24 h intervals in 11 control horses and in nine horses affected with acute laminitis created by administration of a high‐starch ration. Following intra‐arterial injection of technetium‐99m macroaggregated albumin into the brachiocephalic trunk, static images were acquired of the right front foot. Dynamic radionuclide angiograms and static blood pool images were also obtained after jugular vein injection of technetium‐99m diethylenetriamine pentaacetic acid. These procedures were performed on standing horses, using either minimal or no tranquillisation. Images were analysed quantitatively for parameters indicative of circulation to the whole foot and to specific regions within the foot. There was no evidence of reduced total blood flow to the lamellae during either the developmental or acute phases of laminitis. Total flow tended to increase throughout the peripheral/external regions of the foot, but statistically significant elevations were consistently present only within the lamellae. The increased total blood flow to the lamellae may have been due to elevated capillary flow and/or elevated arteriovenous shunt flow. This study did not support lamellar ischaemia as the primary cause of acute equine laminitis.
In vitroresponses of equine digital vessels to dopamine and fenoldopam
Authors: BAXTER G. M. , MOORE J. N. , TACKETT R. L.
Published: April 2010

Thein vitroresponses of isolated vascular preparations of digital arteries and veins obtained from healthy anaesthetised horses were determined for dopamine and fenoldopam. The digital vessels were harvested, cut into 4 mm vascular segments, suspended in tissue baths and attached to force‐displacement transducers. Dose‐response studies between 10−8and 10−4M concentrations were performed for all drugs. The change in tension of each vascular ring was measured in grams of force. The reactivity between palmar and plantar digital vessels and baseline vascular responses were determined for dopamine. The vascular responses of dopamine were compared toin vitrodata for other known vasoconstrictor agents. The mechanism of vasoconstriction induced by dopamine was further defined using prazosin, a specific competitive alpha‐1 adrenoceptor antagonist. The vasodilating ability of fenoldopam, a dopamine‐1 (DA‐1) receptor agonist, was also determined using noradrenaline‐ preconstricted vascular segments from palmar digital vessels. The effective concentration to produce 50 per cent of the maximal response (EC50) and the maximal contraction in grams of force per milligram of the vascular ring (g/mg) were calculated. There were no differences in the reactivity between the palmar and plantar digital vessels. Dopamine produced intense constriction in arteries and veins but only at very high molar concentrations. Prazosin decreased significantly the sensitivity of the veins to dopamine (increased the mean EC50values) but not the arteries. Prazosin had no effect on the maximal contractions of the vessels. Fenoldopam produced very little relaxation of either the arteries or veins. These results suggest that dopamine produces constriction in equine digital arteries and veins and that the constriction is only partially mediated by alpha‐1 adrenoceptors. Also, fenoldopam produced minimal DA‐1 receptor activation in these peripheral vessels.
Squamous cell carcinoma of the equine external genitalia: a review and assessment of penile amputation and urethrostomy as a surgical treatment
Authors: HOWARTH S. , LUCKE V. M. , PEARSON H.
Published: April 2010

A retrospective analysis was performed on 48 cases of suspected neoplasia involving the equine external genitalia. Forty nine squamous cell carcinomata (SCC) and 23 squamous papillomata (SP) were identified. Two cases of epithelial hyperplasia and one case of habronemiasis were also recognised histopathologically. The glans penis was the most common site of tumour development accounting for 53 per cent of cases of SCC and 61 per cent of SP. The urethral diverticulum, urethral process or urethra was involved in 27.6 per cent (8/29) of cases of SCC. Twelve per cent (5/41) of cases of SCC were confirmed to have metastatic involvement of the local lymph nodes. Papillomata showing pre‐malignant changes were identified in five cases. Seventy five per cent (36/48) of the animals presented were ponies. All were geldings, mean age 16.5 years. Penile amputation and urethrostomy, preputial ablation and proximal urethrostomy or local excision were used in the surgical management of these animals; three cases were inoperable and destroyed at presentation. Oedema, haemorrhage and stenosis of the urethrostomy site were encountered as post operative complications. Sixty six per cent (6/9) of animals with SCC of the glans penis (without urethral involvement), which had a known history over the follow up period, treated by penile amputation and urethrostomy survived for longer than 18 months. Similarly, of those with urethral involvement only 28.6 per cent (2/7) survived for a similar follow‐up period. SCC not uncommonly affects the external genitalia of aged pony geldings and frequently the glans penis. If the lesion is identified before local metastasis occurs, penile amputation and urethrostomy is indicated and the prognosis is favourable.
Muscle disorders in the horse: a retrospective study
Authors: FREESTONE J. F. , CARLSON G. P.
Published: April 2010

Case records of horses with muscle disorders presenting to the Veterinary Medical Teaching Hospital of the University of California, Davis, over a nine year period were evaluated. The objectives of the review were to identify the common myogenic muscle problems and their clinical features. Muscle disease of idiopathic aetiology following exercise was by far the most common condition noted. Other causes of myogenic muscle disorders included congenital, infectious, immune‐mediated and nutritional factors.
Muscle fibre type composition in untrained and endurance‐trained Andalusian and Arab horses
Authors: LOPEZ‐RIVERO J. L. , MORALES‐LOPEZ J. L. , GALISTEO A. M. , AGUERA E.
Published: April 2010

Muscle biopsies were taken from the middle gluteal muscle of 68 stallions (52 Andalusian [AN] and 16 Arab [AR]) ranging from six to 12 years of age. Seventeen AN horses and eight AR horses were untrained, while the remainder underwent active endurance training for 6 months. Fifteen AN horses were moderately endurance‐trained while the other 20 AN horses and eight AR horses were strongly endurance‐trained. Percentages of type I and type II fibres were similar in all groups (P>0.05). The group of horses with the hardest training had a higher percentage of type HA fibres (AN P<0. 01; AR P<0.02) and a lower percentage of type IIB fibres (P<0.05 for AN and AR) than the untrained horses. All trained horses had a higher percentage of type IIB oxidative fibres and a lower percentage of type IIB non‐oxidative fibres than the untrained horses (P<0.01 for both). These results suggest that the proportions of type I and type II fibres are highly stable within a given breed, but the stimulus of training facilitates changes both in contractile properties and, particularly, in the oxidative capacity of type II subgroups.
Preferential denervation of the adductor muscles of the equine larynx I: muscle pathology
Authors: DUNCAN I. D. , AMUNDSON J. , CUDDON P. A. , SUFIT R. , JACKSON K. F. , LINDSAY W. A.
Published: April 2010

The laryngeal muscles of 18 horses were examined histologically. The neurogenic changes found in each muscle were scored by four reviewers and the results evaluated statistically. Fifteen of these horses had endoscopic evidence of abnormal laryngeal function, three of which were defined as having adductor paralysis. Measurement of muscle fibre area in two horses with idiopathic laryngeal hemiplegia (ILH) was performed. In the quantitative study of neurogenic change, the adductor muscles were more significantly affected than the abductor muscle. This was also true in the clinical cases of ILH where measurement of muscle Fibre area demonstrated that the lateral cricoarytenoid (adductor) muscle showed a wider range of pathological changes than the dorsal cricoarytenoid muscle (abductor). Those horses with the most severe muscle pathology also had the most abnormal endoscopic findings. The propensity for denervation of the adductor muscles should provide clues as to the pathogenesis and natural history of horses with sub‐clinical laryngeal disease and ILH.
Preferential denervation of the adductor muscles of the equine larynx II: Nerve pathology
Authors: DUNCAN I. D. , REIFENRATH P. , JACKSON K. F. , CLAYTON M.
Published: April 2010

The terminal branches of the recurrent laryngeal nerve (RLN) of three normal ponies and six horses with sub‐clinical laryngeal disease were examined qualitatively and quantitatively in an attempt to explain the preferential denervation of the laryngeal adductor muscles in the neuropathy of idiopathic laryngeal hemiplegia (ILH). The myelinated fibre spectra of all the motor nerve fibres in the left and right abductor and adductor branches of the RLN in three normal ponies were measured. The density of myelinated fibres was also calculated. There was no significant difference between the larger group of myelinated fibres in the adductor or abductor branches. In the six horses with laryngeal hemiparesis, however, there was a marked preferential loss of the medium/large size myelinated fibres in the left adductor branch, although nerve fibre densities were not significantly different. While no simple morphometrical feature was found to explain the selective muscle denervation, the greater loss of large diameter myelinated fibres in the adductor branches confirms the earlier observation of adductor muscle susceptibility in the neuropathy of ILH.
An outbreak of Equid herpesvirus abortion in New South Wales
Authors: CARRIGAN M. , COSGROVE P. , KIRKLAND P. , SABINE MARGARET
Published: April 2010

Thirty‐three of the 44 mares on a Thoroughbred stud in New South Wales aborted or lost foals within one day of birth. Gross pathological and histological changes were in keeping with Equid herpesvirus I (EHV‐1) abortion. In the six foals that underwent virological examination, EHV was isolated and typed as EHV‐1 by restriction endonuclease analysis. EHV‐1 abortion had not occurred previously on this stud and the source of the infection was not identified.
An investigation of the incidence of chronic obstructive pulmonary disease (COPD) in random populations of Swiss horses
Authors: BRACHER VERENA , von FELLENBERG R. , WINDER CHRISTINE N. , GRUENIG GABRIELE , HERMANN M. , KRAEHENMANN A.
Published: April 2010

The incidence of Chronic Obstructive Pulmonary Disease (COPD) in Switzerland was determined in three groups of horses selected at random. Group A (97 horses) and Group B (93 horses) had no history of respiratory disease, but Group C (113 horses) had a history of lower respiratory tract disease. All horses were examined by auscultation of the respiratory tract under forced, breathing, endoscopic examination of the upper and lower. respiratory tract, arterial blood gas analysis at rest and cytological examination of respiratory secretions (RS). Fifty‐four per cent of the horses in Group A and 54.8 per cent of Group B were diagnosed as suffering clinical COPD and only 12.4 per cent of horses in Group A and 8.6 per cent in Group B had no detectable abnormalities in their lower respiratory tracts. In Group B, 19.4 per cent were considered to be suffering from parasitic pulmonary disease indicated by elevated numbers of eosinophils in their RS. Pharyngeal lymphoid hyperplasia was exhibited in 70.1 per cent of Group A and 74.2 per cent of Group B. Cytological examination of RS was useful to determine if the secretions found in the trachea originated from the upper or lower respiratory tract. Arterial blood gas analysis revealed no significant differences between healthy horses and those with subclinical or mild COPD.
Osteochondritis dissecans of the tarsocrural joint: results of treatment with arthroscopic surgery
Authors: McILWRAITH C. W. , FOERNER J. J. , DAVIS D. M.
Published: April 2010

The technique and results of arthroscopic surgery for the treatment of osteochondritis dissecans in 318 tarsocrural joints in 225 horses are reported. Of the 225 horses, 154 were racehorses or intended for racing. Arthroscopic surgery was an effective technique for treating osteochondritis dissecans of the tarsocrural joint. The overall functional ability and cosmetic appearance of the limbs were excellent. Post surgical follow‐up information was obtained for 183 horses, of which 140 (76.5 per cent) raced successfully or performed their intended use following surgery. Of the remaining 43, 11 were considered to still have a tarsocrural joint problem, 19 developed other problems precluding successful performance, eight were considered poor racehorses without any lameness problems identified, three were killed because of septic arthritis and two died from other causes. There was no significant effect of age, sex or limb involvement on the outcome. The size of the intermediate ridge lesions had no effect on prognosis but the presence of degenerative or erosive changes in the articular cartilage significantly decreased the prognosis. The synovial effusion resolved in 117/131 racehorse joints (89.3 per cent) and 64 of 86 non‐racehorse joints (74.4 per cent) with follow‐up. The outcome for synovial fluid resolution was significantly inferior for lesions of the lateral trochlear ridge of the talus or medial malleolus of the tibia compared to distal intermediate ridge lesions. There was no significant relationship between resolution of effusion and successful performance outcome.
Arthroscopic removal of osteochondral fragments of the palmar/plantar aspect of the metacarpo/metatarsophalangeal joints
Authors: HOUTTU JUKKA
Published: April 2010

This paper presents the results of arthroscopic surgery in 42 Standardbred trotters and three Finnish horses. Forty‐five horses were operated on. The age range was one to seven years; 73 per cent of the horses were three years old or younger. Horses showed a variety of clinical signs ranging from moderate to severe lameness at slow speeds, to obscure lameness manifesting only at high speeds. Synovial effusion of the fetlock joint was rare. In this series, 44 horses that had Type I fragments and one horse that had Type III fragments were operated on. Of the 45 horses operated on, 23 (51 per cent) returned to speed training in three months and 41 (91 per cent) returned to speed training in six months. Three of 45 (6 per cent) were lame three months after the surgery when the trainer attempted to start speed training. One of those was sound six months after the operation. The remaining two (4 per cent) stayed lame due to a lesion in the affected joint. Two of 45 (4 per cent) discontinued training for other reasons. The horse with Type III fragments returned to speed training in three months.
Relative incidence of dorsal metacarpal disease in young Thoroughbred racehorses training on two different surfaces
Authors: MOYER W. , SPENCER PAMELA A. , KALLISH MICHELE
Published: April 2010

The relative incidence of dorsal metacarpal disease was examined in two groups of Thoroughbred racehorses training on dissimilar surfaces (dirt and wood fibre). The horses and training methods appeared to be similar. The incidence of disease was significantly greater in the group training on dirt. There was no significant difference in the age distribution of incidence between the two groups and there was no association of incidence with sex or age within the training group. The number of fast miles worked by the two groups prior to the onset of dorsal metacarpal disease was lower in the group training on dirt.
Assessment of the breeding prognosis of mares using paired endometrial biopsy techniques
Authors: RICKETTS S. W. , ALONSO SILVIA
Published: April 2010

Paired endometrial biopsy samples were taken from 530 subfertile mares, before and after treatment (where indicated) and a period of sexual rest. Prognoses were made after each biopsy (Categories 1A‐4A before treatment and Categories 1B‐4B after treatment), using histopathological criteria similar to those described by Kenney and Doig (1986). Eighty‐seven per cent of the mares were assigned to first biopsy prognosis Category 3A. The second biopsy prognosis produced a more even population distribution (10, 47, 40 and 3 per cent respectively for Category 1B, 2B, 3B and 4B mares). First biopsy Category 3A and 4A mares produced mean foaling rates of 51 and 40 per cent respectively. None of the 14 second biopsy Category 4B mares delivered a live foal (12 were barren, one aborted and one suffered early foetal death). This study supports the hypothesis that a breeding prognosis assigned on the basis of two endometrial biopsy samples, taken before and after specific uterine treatment, where indicated, which takes into consideration the mare's ability to respond to treatment, is likely to be more accurate than one assigned after a single biopsy sample.
The effect of age and parity on the development of equine chronic endometrial disease
Authors: RICKETTS S. W. , ALONSO SILVIA
Published: April 2010

The results of a retrospective analysis of 3,804 endometrial biopsy specimens collected from non‐pregnant mares during the course of routine equine stud farm practice demonstrates a significant and practically useful correlation between the severity of chronic degenerative endometrial disease (CDE) diagnosed and age of mare at the time of examination. There were significant correlations between the number of foals born and the mares' barren years prior to biopsy and the severity of CDE, but the differences were not sufficiently large to be useful. Correlations between the severity of chronic infiltrative endometritis (CIE) and age or pre‐biopsy parity were minimal. The results suggest that using similar histopathological criteria to those used by Kenney and Doig (1986), mares up to nine years of age should have no signs of CDE, mares up to 13 years of age should have no more than mild signs, mares up to 15 years of age should have no more than moderate signs and mares aged 17 years or older are likely to have severe signs. We believe that these guidelines are a useful, objective aid for formulating a breeding prognosis.
Equine helminth infections: control by selective chemotherapy
Authors: GOMEZ H. HAMLEN , GEORGI J.R.
Published: April 2010

A programme of selective anthelmintic therapy was used in a herd of 31 horses. Faecal egg counts were done during the months of September, November, January, March, May and the following September. Horses with ≥100 eggs per gram (epg) were treated with ivermectin, and those with <100 epg were not treated. The criteria for adequate internal parasite control in the herd was a median herd faecal egg count of ≤100 epg. Effectiveness of selective therapy was assessed by faecal egg count after nine months of treatment and was determined to be adequate when a median herd egg count of 0 epg was obtained. However, on returning from pasture the following September, median herd egg count had risen to 325 epg. A statistically significant correlation was seen in the paired September faecal egg counts of the horses in that initial September faecal egg count was predictive for the following September. Initial September faecal egg count was related to the number of anthelmintic treatments required during the period of selective therapy, whereas age of horse was not. We propose that faecal egg counts be incorporated into strategic anthelmintic programmes as an economical tool for identifying and targeting herd members predisposed to shedding elevated numbers of helminth eggs.
Antithrombin III activity in horses with colic: an analysis of 46 cases
Authors: DARIEN B. J. , POTEMPA J. , MOORE J. N. , TRAVIS J.
Published: April 2010

Antithrombin‐III (AT‐III) activity was measured at the time of admission in 46 horses referred with colic. Differences in AT‐III activities between animals treated medically or surgically and survivors or non‐survivors were compared. The mean AT‐III values for the horses treated medically (76.2 per cent), surgical survivors (69.5 per cent) and surgical non‐survivors (55.9 per cent) were significantly different from the reference value for healthy adults (92 to 108 per cent). The mean AT‐III activity of the survivors was significantly (P<0.01) greater than that of the non‐survivors. The majority of the survivors (11 of 13 horses) had AT‐III activities exceeding 60 per cent of normal, whereas that of 10 of the 14 non‐survivors was less than 60 per cent of normal. There was an apparent distinction between the survivors and non‐survivors at approximately 60 per cent of normal AT‐III activity.
Anatomical and functional communications between the synovial sacs of the equine stifle joint
Authors: REEVES M. J. , TROTTER G. W. , KAINER R.A.
Published: April 2010

The anatomical and functional communications of the synovial sacs of the equine stifle joint were evaluated in 50 stifle joints of 25 horses. Femoropatellar joint (FPJ) sacs were injected with 50 ml of gelatin‐based dye and horses were then walked for 50 m. Horses were subsequently killed, the stifle joints dissected and the location of the dye recorded. Twenty‐three horses (46 joints) had clinically normal stifle joints and in this group, anatomical communications of the stifle joints were bilaterally symmetrical in each horse. In 15 of these 23 horses (65 per cent), direct anatomical communication between the FPJ sac and the medial sac of the femorotibial joint (FTJ) was demonstrated. The FPJ sac communicated with both the medial and lateral sacs of the FTJ in four of these 23 horses (17.5 per cent). There were no anatomical communications between the FPJ sac and either sac of the FTJ in the remaining four horses (17.5 per cent). Functional communication, which was established by finding dye in the FTJ sacs where anatomical communication with the FPJ sac existed, was demonstrated in 14 of 19 horses (74 per cent). Two horses were affected with degenerative joint disease of one stifle joint. In both of these joints the FPJ sac communicated with both the medial and lateral FTJ sacs. This distribution was different from that of the contralateral joint. When performing intra‐articular anaesthesia of equine stifle joints, each synovial sac needs to be injected separately to ensure that anaesthesia of the appropriate synovial sac is obtained.
Laminitis in the pony: conservative treatment vs dorsal hoof wall resection
Authors: Peremans K. , Verschooten F. , de Moor A. , Desmet P.
Published: April 2010

The clinical and radiographic findings in 21 ponies with laminitis and its treatment and results are described. All ponies received non‐steroidal anti‐inflammatory drugs. All were fed hay and no concentrates. They were box rested for varying periods depending on clinical improvement. Dorsal hoof wall resection was performed in 11 ponies and all regained complete soundness. To shorten the period of non‐activity, working ponies were shod and the hoof wall defect was packed with technovit or a combination of glue with cotton cuttings. Ten were treated conservatively; two recovered completely, four remained lame and four were killed because of recurrent laminitis.
Pulmonary gas exchange correlated to clinical signs and lung pathology in horses with chronic bronchiolitis
Authors: NYMAN G. , LINDBERG R. , WECKNER D. , BJÖRK M. , KVART C. , PERSSON S. G. B. , GUSTAFSSON H. , HEDENSTIERNA G.
Published: April 2010

Eight horses (mean weight 438 kg) with chronic obstructive pulmonary disease (COPD) were studied for clinical signs, ventilation/perfusion relationships (V̇A/Q̇) and lung morphology. Four horses were killed and necropsied after the study. In horses with COPD, minute ventilation was almost twice as high as normal, whereas PaO2 was significantly decreased. Cardiac output was normal, but pulmonary artery pressure and pulmonary vascular resistance were significantly increased. The V̇A/Q̇ distribution was abnormal with an increased scatter of V̇A/Q̇ ratios. However, shunt (V̇A/Q̇=0) was increased in one horse only. Ventilation of dead space and high V̇A/Q̇ regions (V̇A/Q̇>10) were increased markedly and comprised 74 per cent of minute ventilation. On lung biopsy, all horses showed chronic bronchiolitis with epithelial hyperplasia and metaplasia. Diffuse acinar hyperinflation also was evident at necropsy. There was a significant inverse correlation between the respiratory rate and the fractional ventilation of normal V̇A/Q̇ regions. Also, there was a significant agreement between the extent of bronchiolar epithelial hyperplasia in necropsy specimens of lungs and the degree of ventilation of high V̇A/Q̇ regions and dead space. The findings suggest that hyperinflation of the lung due to obstructed airways may be the common denominator of increased ventilation of high V̇A/Q̇ regions and dead space ventilation and of elevated pulmonary artery pressure in horses with COPD from chronic bronchiolitis.
Evaluation of transabdominal ultrasound‐guided amniocentesis in the late gestational mare
Authors: SCHMIDT A. R. , WILLIAMS M. A. , CARLETON C. L. , DARIEN B. J. , DERKSEN F. J.
Published: April 2010

Serial transabdominal amniocentesis was performed on eight mares in late gestation. Ultrasonography was used to identify the two placental fluid sacs and the foetus. A biopsy guide attached to the transducer allowed visualisation of the needle path during insertion. Amniotic fluid was obtained in 85 per cent of the attempts, although as mares approached parturition substantial pools of amniotic fluid were more difficult to locate. Two mares aborted during the study probably because of complications of the procedures, whereas six mares produced normal foals at term. The abortions preclude clinical use of this technique currently. However, there was sufficient success in retrieval of amniotic fluid and outcome of pregnancies to continue the study of amniocentesis in larger groups of mares to determine the clinical and research value of this technique.
Pharmacokinetic, biochemical and tolerance studies on carprofen in the horse
Authors: McKELLAR Q. A. , BOGAN J. A. , von FELLENBERG R.‐L , LUDWIG B. , CAWLEY G. D.
Published: April 2010

Carprofen, a non‐steroidal anti‐inflammatory drug (NSAID) was administered to three Thoroughbred geldings and three Shetland ponies to determine its plasma disposition and tolerance. The main pharmacokinetic characteristics of carprofen in horses and ponies were a volume of distribution of 0.08 to 0.32 litres/kg (mean ± se=0.23 ± 0.04) a systemic clearance of 26.4 to 78.5 ml/min (mean ± se=44.9 ± 8.0) and a plasma elimination half‐life of 14.5 to 31.4 h (mean ± se=21.9 ± 2.3). There was no evidence of any accumulation of carprofen in plasma when the drug was given orally at a dose rate of 0.7 mg/kg for 14 consecutive days. Carprofen was well tolerated following intravenous (iv) and oral administration. Intramuscular (im) administration resulted in elevated levels of plasma creatine kinase suggesting muscle cell damage. According to the results of this study carprofen can be regarded as a long‐acting NSAID in horses from a pharmacokinetic point of view. Either iv, im or the oral route of administration could be used to achieve high carprofen plasma concentrations.
An epidemiological study of summer eczema in Icelandic horses in Norway
Authors: Halldórdsóttir Stefania , Larsen H. J.
Published: April 2010

A survey of summer eczema was conducted on 391 Icelandic horses in Norway. The study showed a prevalence of summer eczema of 17.6 per cent in the horses investigated. Icelandic horses born in Norway where shown to be less affected with summer eczema than imported horses, 8.2 per cent and 26.9 per cent respectively (P < 0.001). There was no difference in the prevalence of summer eczema relative to gender or colour of the horse. The number of horses affected with summer eczema rose with increasing age and the number of years which had elapsed since importation. On average, Icelandic horses born in Norway developed summer eczema at the age of 5.3 years. The onset of disease for imported horses was, on average, 4.1 years after importation. The study also revealed that a significantly greater number of horses imported from Iceland to Norway during the period October to April, which has a minimal or low activity of insects (32.3 per cent), had developed summer eczema, compared with horses imported during the period May to September, when insects are more active (16.7 per cent), (P=0.044). Horses with summer eczema were shown to be significantly more affected by respiratory disease than non‐affected horses (P=0.0086). The most common sites and clinical signs of summer eczema are also described.
Small intestinal malabsorption in the horse: an assessment of the specificity of the oral glucose tolerance test
Authors: MAIR T. S. , HILLYER M. H. , TAYLOR F. G. R. , PEARSON G. R.
Published: April 2010

Specificity of the oral glucose tolerance test (OGTT) for the diagnosis of small intestinal malabsorption in the horse was assessed by comparing the results of OGTT with the results of a histopathological examination of the small intestine in 42 adult horses affected by chronic weight loss. The horses were assigned to three groups on the basis of the results of the test. Five horses were considered to have a normal OGTT absorption result (Group 1); all the horses had a histologically normal small intestine. Twenty‐five horses had a partial malabsorption result (Group 2) seven of which had normal small intestinal morphology, whereas the remaining 18 had a variety of pathological lesions including lymphosarcoma, villous atrophy, granulomatous enteritis and eosinophilic gastroenteritis. Twelve of the 42 horses had a total malabsorption result (Group 3), and all had a severe infiltrative lesion in the small intestinal wall (either lymphosarcoma or granulomatous enteritis).