bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of strain and stress in the equine hoof capsule using finite element methods: comparison with principal strains recorded in vivo
Authors: THOMASON J. J. , McCLINCHEY H. L. , JOFRIET J. C.
Published: April 2007

Finite‐element (FE) methods have great potential in equine biomechanics in evaluating mechanical stresses and strains in tissues deep within the hoof. In this study, we critically assessed that potential by comparing results of FE analyses of capsular strain with in vivo data. Nine FE models were developed, corresponding to the shape of hooves for which in vivo principal strain data are available. Each model had the wall, laminarjunction, sole and distal phalanx (PIII). In a first loading condition (LC1), force is distributed uniformly to the bearing surface of the wall to determine reaction forces and moment on PIII. These reaction forces were subsequently applied to PIII in loading condition 2 (LC2) to simulate loading via the skeleton. Magnitude of the force resultant was equivalent to the vertical force on the hoof at midstance. Principal compressive strains ε2 were calculated at the locations of 5 rosette gauges on the real hooves and are compared with the in vivo strains at midstance.

FE strains were from 16 to 221% of comparable in vivo values, averaging 104%. All models in this, and reports by other workers, show predominance of stress and strain at the toe to a greater extent than in the real hoof. The primary conclusion is that FE modelling of strain in the hoof capsule or deeper tissues of individual horses should not be attempted without corroborating experimental data.
Dynamics in serum of the inflammatory markers serum amyloid A (SAA), haptoglobin, fibrinogen and α2‐globulins during induced noninfectious arthritis in the horse
Authors: HULTÉN C. , GRÖNLUND U. , HIRVONEN J. , TULAMO R. ‐M. , SUOMINEN M. M. , MARHAUG G. , FORSBERG M.
Published: April 2007

Despite the importance of noninfectious joint diseases in equine medicine, little is known about the acute phase response which may be elicited if the local inflammatory process of noninfectious arthritis is sufficiently strong, Therefore the aim of this study was to monitor the systemic inflammatory response during experimentally‐induced noninfectious arthritis by studying the dynamics in serum of the acute phase proteins serum amyloid A (SAA), haptoglobin, fibrinogen and α2‐globulins. Twenty‐four Standardbred horses, age 3–7 years, found healthy on thorough clinical, radiological, haematological and serum biochemical examination, were injected aseptically into the right midcarpal joint with amphotericin B. Blood samples were drawn before induction of arthritis (0 h), and at 8, 16, 24, 36 and 48 h postinduction and then on Days 3, 4, 5 and 15 postinduction. All horses developed lameness with joint effusion and joint heat as well as increased respiratory rate, heart rate and body temperature. The lameness started to decline after 24–36 h and, in most animals, systemic signs disappeared on Day 2 postinjection. The concentration of the acute phase proteins increased following induction of arthritis. The SAA concentrations were higher than baseline concentrations from 16 h postinduction and were maximal at 36–48 h (227 times baseline concentration). The haptoglobin concentrations were higher than baseline concentrations from 24 h and were maximal at 48–96 h (1.14 times baseline concentration). The maximal concentrations of fibrinogen were seen between 36–72 h postinjection and increased on average 0.87 times from baseline concentrations. The fibrinogen concentrations were higher than baseline concentrations from 24 h postinjection. α2‐globulins concentrations showed a minor in crease and increased 0.55 times from baseline concentrations. The markers had returned to baseline concentrations by Day 15.

Our results demonstrate that amphotericin B‐induced arthritis in a single joint gives rise to a systemic acute phase response measurable as increased concentrations in serum SAA, haptoglobin, fibrinogen and α2‐globulins during the first 2 weeks of the condition and, thereby, that such an increase need not be indicative of infectious arthritis. Further research should be aimed at determining whether chronic noninfectious arthritis in the horse gives rise to increased acute phase protein concentrations in serum.
Ultrasonographic anatomy and biometric analysis of the thoracic and abdominal organs in healthy foals from birth to age 6 months
Authors: ALEMAN M. , GILLIS C. L. , NIETO J. E. , RENAUDIN C. D. , BEA J.
Published: April 2007

Knowledge of normal renal parameters, as documented in mature horses, is essential for the accurate evaluation of abnormal kidneys. Although the ultrasonographic appearance and location of the abdominal organs in foals and the renal dimensions in neonates have been reported, there is currently no information available for the assessment of normal organ growth in foals. The objectives of the study were to describe the ultrasonographic characteristics, location and variations of the thoracic and abdominal organs with relation to age, height and weight; and provide a growth table for comparison with diseased foals. The thoracic and abdominal cavities of 10 healthy foals were evaluated at ages 1, 7, 14 and 21 days and 1, 2, 3, 4, 5 and 6 months. The equipment used was an Ausonics Opus Plus ultrasound. For every evaluation, weight and height were obtained, the foals were sedated and the area of study was clipped and cleaned. The ultrasonographic location, appearance and measurements of the different organs were recorded for each examination. The study revealed that foals age >1 month resemble the mature ultrasonographic pattern. Continual growth of the organs was observed from Day 1 to age 6 months, being faster in the first month. Organ growth was closely correlated with age, but not with sex, height or weight in healthy foals up to age 6 months. Our study has provided measurements of longitudinal organ growth in healthy foals, presented in a simple form for easy comparison with diseased individuals.
Hysteroscopic insemination of mares with low numbers of nonsorted or flow sorted spermatozoa
Authors: LINDSEY A. C. , MORRIS L. H. A. , ALLEN W. R. , SCHENK J. L. , SQUIRES E. L. , BRUEMMER J. E.
Published: April 2007

The objectives of this study were 1) to compare pregnancy rates resulting from 2 methods of insemination using low sperm numbers and 2) to compare pregnancy rates resulting from hysteroscopic insemination of 5 × 106 nonsorted and 5 × 106 spermatozoa sorted for X‐ and Y‐chromosome‐bearing populations (flow sorted). Semen was collected with an artificial vagina from 2 stallions of known acceptable fertility. Oestrus was synchronised (June to July) in 40 mares, age 3–10 years, by administering 10 ml altrenogest orally for 10 consecutive days, followed by 250 μg cloprostenol i.m. on Day 11. All mares were given 3000 iu hCG i.v. at the time of insemination to induce ovulation. Mares were assigned randomly to 1 of 3 treatment groups: mares in Treatment 1 (n = 10) were inseminated with 5 × 106 spermatozoa deposited deep into the uterine horn with the aid of ultrasonography. Mares in Treatment 2 (n = 10) were inseminated with 5 × 106 spermatozoa deposited onto the uterotubal junction papilla via hysteroscopic insemination. Mares in Treatment 3 (n = 20) were inseminated using the hysteroscopic technique with 5 × 106 flow sorted spermatozoa. Spermatozoa were stained with Hoechst 33342 and sorted into X‐ and Y‐chromosome‐bearing populations based on DNA content using an SX MoFlo sperm sorter. Pregnancy was determined ultrasonographically at 16 days postovulation. Hysteroscopic insemination resulted in more pregnancies (5/10 = 50%) than did the ultrasound‐guided technique (0/10 = 0%; P<0.05) when nonsorted sperm were inseminated. Pregnancy rates were not significantly lower (P>0.05) when hysteroscopic insemination was used for sorted (5/20 = 25%) and nonsorted spermatozoa (5/10 = 50%). Therefore, hysteroscopic insemination of low numbers of flow sorted stallion spermatozoa resulted in reasonable pregnancy rates.
Subjective and quantitative scintigraphic assessment of the equine foot and its relationship with foot pain
Authors: DYSON S. J.
Published: April 2007

It was hypothesised that in solar bone images of the front feet of clinically normal horses, or horses with lameness unrelated to the front feet, there would be less than a 10% difference in the ratio of uptake of radiopharmaceutical in either the region of the navicular bone, or the region of insertion of the deep digital flexor tendon (DDFT), compared to the peripheral regions of the distal phalanx. Nuclear scintigraphic examination of the front feet of 15 Grand Prix show jumping horses, all of which were free from detectable lameness, was performed using dorsal, lateral and solar images. The results were compared with the examinations of 53 horses with primary foot pain, 21 with foot pain accompanying another more severe cause of lameness and 49 with lameness or poor performance unrelated to foot pain. None of the horses with foot pain had radiological changes compatible with navicular disease. All the images were evaluated subjectively. The solar views were assessed quantitatively using regions of interest around the navicular bone, the region of insertion of the deep digital flexor tendon and the toe, medial and lateral aspects of the distal phalanx. In 97% of the feet of normal showjumpers, there was <10% variance of uptake of the radiopharmaceutical in the navicular bone, the region of insertion of the DDFT and the peripheral regions of the distal phalanx. There was a significant difference in uptake of radiopharmaceutical in the region of the navicular bone in horses with foot pain compared to normal horses. There was a large incidence of false positive results related to the region of insertion of the DDFT. Lateral pool phase images appeared more sensitive in identifying potentially important DDFT lesions. There was a good correlation between a positive response to intra‐articular analgesia of the distal interphalangeal joint and intrathecal analgesia of the navicular bursa and increased uptake of radiopharmaceutical in the region of the navicular bone in the horses with primary foot pain. It is concluded that quantitative scintigraphic assessment of bone phase images of the foot, in combination with local analgesic techniques, can be helpful in the identification of the potential source of pain causing lameness related to the foot, but false positive results can occur, especially in horses with low heel conformation.
A comparison of three horseshoeing styles on the kinetics of breakover in sound horses
Authors: ELIASHAR E. , McGUIGAN M. P. , ROGERS K. A. , WILSON A. M.
Published: April 2007

A variety of horseshoe designs are believed to ‘ease’ breakover, or the unloading of the foot once the heels leave the ground. In this study, conventional toe‐clip shoes, quarter‐clip shoes, fitted to the white line at the toe, and Natural Balance horseshoes were fitted to the front feet of 9 sound Irish Draught‐cross type horses. Forceplate and video motion analyses were undertaken during trot locomotion to determine the moment arm of the ground reaction force on the distal interphalangeal (DIP) joint, the peak DIP joint moment and the peak compressive force on the navicular bone. DIP joint moment arm during breakover was reduced with both Natural Balance (mean ± s.d. 77 ± 7 mm) and quarter‐clip shoes (78 ± 9 mm) compared to the toe‐clip shoes (86 ± 6 mm) (P<0.01). Peak DIP joint moment was not significantly different (175 ± 37, 171 ± 38 and 175 ± 31 Nmm/kg, in Natural Balance, quarter‐clip and toe‐clip shoes, respectively) and neither was peak force on the navicular bone (5.52 ± 1.52, 5.79 ± 1.53 and 6.14 ± 1.47 N/kg, respectively). Breakover duration (heel off to toe off) was not significantly reduced by the Natural Balance shoes (39 ± 6 ms) or the quarter‐clip shoes (40 ± 6 ms) compared to toe‐clip shoes (42 ± 9 ms). This study has demonstrated that the use of Natural Balance shoes reduces the moment arm of the ground reaction force (GRF) during breakover but does not reduce the peak DIP joint moment or the force on the navicular bone.
Hysteroscopic insemination of low numbers of flow sorted fresh and frozen/thawed stallion spermatozoa
Authors: LINDSEY A. C. , SCHENK J. L. , GRAHAM J. K. , BRUEMMER J. E. , SQUIRES E. L.
Published: April 2007

The objective of this experiment was to determine the effects of flow cytometric sorting and freezing on stallion sperm fertility. A 2 × 2 factorial design was used to delineate effects of flow sorting and freezing spermatozoa. Oestrus was synchronised (July‐August) in 41 mares by administering 10 ml altrenogest (2.2 mg/ml) per os for 10 consecutive days, followed by 250 μg cloprostenol i.m. on Day 11. Ovulation was induced by administering 3000 iu hCG i.v. either 6 h (fresh spermatozoa) or 30 h (frozen/thawed spermatozoa) prior to insemination. Mares were assigned randomly to one of 4 sperm treatment groups. Semen was collected from 2 stallions with an artificial vagina and processed for each treatment. Treatment 1 (n = 10 mare cycles) consisted of fresh, nonsorted spermatozoa and Treatment 2 (n = 16 mare cycles) of fresh, flow sorted spermatozoa. Spermatozoa to be sorted were stained with Hoechst 33342 and sorted into X‐ and Y‐chromosome‐bearing populations based on DNA content using an SX MoFlo sperm sorter. Treatment 3 (n = 16 mare cycles) consisted of frozen/thawed nonsorted spermatozoa (frozen at 33.5 × 106 sperm/ml in 0.25 ml straws) and Treatment 4 (n = 15 mare cycles) of flow sorted frozen/thawed spermatozoa (frozen at 64.4 × 106 sperm/ml). Concentrations of sperm in both cryopreserved treatments were adjusted, based on predetermined average post‐thaw motilities, so that each insemination contained approximately 5 × 106 motile spermatozoa. Hysteroscopic insemination of 5 × 106 motile spermatozoa in a volume of 230 μl was used for all treatments. Pregnancy was determined ultrasonographically 16 days postovulation.

No differences were found (P>0.1) in the pregnancy rates for mares inseminated with fresh nonsorted (4/10 = 40.0%), fresh flow sorted (6/16 = 37.5%), frozen/thawed nonsorted (6/16 = 37.5%) and flow sorted frozen/thawed spermatozoa (2/15 = 13.3%). Pregnancy rates tended (P = 0.12) to be lower following insemination of frozen/thawed flow sorted spermatozoa. Further studies are needed with a larger number of mares to determine if fertility of flow sorted frozen/thawed spermatozoa can be improved.
An evaluation of diagnostic data in comparison to the results of liver biopsies in mature horses
Authors: DURHAM A. E. , SMITH K. C. , NEWTON J. R.
Published: April 2007

Reasons for performing study: The diagnostic value of several investigative procedures commonly used during the evaluation of suspected equine hepatopathy cases has not been specifically quantified in previous studies.

Hypothesis: No noninvasive procedures would clearly discriminate between horses with and without significant liver disease.

Methods: Histopathology of biopsy samples was used as the ‘gold standard’ technique for definitive diagnosis of the presence or absence of significant liver disease. Clinical, ultrasonographic and clinicopathological data obtained during the investigation of 82 suspected cases of hepatopathy in mature horses were compared with the results of subsequent biopsy in order to quantify the diagnostic value of each test.

Results: Of the 82 cases, 61 were confirmed to have significant liver disease and 21 were not. Only serum concentrations of gamma‐glutamyltransferase (γGT), globulins and alkaline phosphatase (AP) were found to be significantly different between the 2 groups of horses. Clinical and ultrasonographic abnormalities were found, when present, to be good indicators of the presence of liver disease. Certain single serum biochemical tests and combinations thereof were found to have high values for sensitivity (Sn), specificity (Sp), positive predictive value (PPV) and/or negative predictive value (NPV), but none showed high values for all 4 parameters leading to important limitations in their practical diagnostic application. Of all serum biochemical tests studied, the PPVs of only γGT and globulins could be clearly improved by considering especially high positive results.

Conclusions: The single positive test results of greatest diagnostic value were presence of hepatic encephalopathy (HE), increased γGT, hyperglobulinaemia, hypoalbuminaemia, increased AP, increased total bile acids (TBA) and increased total bilirubin (TBil). Increased aspartate aminotransferase (AST) and increased glutamate dehydrogenase (GLDH) were also of good diagnostic value, but only when used in combination with the above tests. However, no single, combination or sequential test was able to discriminate fully between horses with and without biopsyconfirmed liver disease and reliance on the use of noninvasive tests for the prediction of the presence or absence of significant liver disease may lead to frequent diagnostic errors. Although certain positive results did reliably predict the presence of liver disease, negative test results were invariably poor predictors of the absence of liver disease.

Potential relevance: Application of the findings in this study may not be directly applicable to other case populations. However, the results may help clinicians with their selection and interpretation of appropriate test results in cases of suspected liver disease.
Endoscopic surgery in the treatment of contaminated and infected synovial cavities
Authors: WRIGHT I. M. , SMITH M. R. W. , HUMPHREY D. J. , EATON‐EVANS T. C. J. , HILLYER M. H.
Published: April 2007

Reasons for performing study: Contamination and infection of synovial cavities are a common occurrence in clinical practice and, if inadequately treated, may have career or life threatening consequences for affected horses.

Hypothesis: The objectives in treating contamination and infection of joints, tendon sheaths and bursae are most effectively met by endoscopic surgery.

Methods: Over a 6 year period, cases of synovial contamination and infection admitted to a referral clinic were evaluated and treated endoscopically. The horses received local and systemic antimicrobial drugs with minimal nonsteroidal anti‐inflammatory medication but no other medical or surgical treatment. All arthroscope and instrument portals and, when ever possible, all traumatic wounds were closed. Diagnostic information, endoscopic observations and results of treatment were evaluated retrospectively.

Results: A total of 140 affected animals were referred and 121 cases were treated endoscopically. These involved 70 joints, 29 tendon sheaths, 10 bursae and in 12 cases a combination of synovial cavities. The most common aetiologies were open wounds (n = 54) and self‐sealing punctures (n = 41). Foreign material was identified endoscopically in 41 but predicted prior to surgery in only 6 cases. Osteochondral lesions were evident at surgery in 51 and recognised before surgery in 25 cases; 32 horses had intrathecal tendon or ligament defects.

Follow‐up information was obtained for 118 animals; 106 (90%) survived and 96 (81%) returned to their preoperative level of performance. The presence of osteitis/osteomyelitis, other osteochondral lesions and marked deposits of pannus were associated with nonsurvival. For those animals which survived, non‐Thoroughbred horses, a combination of synovial structure involvement and regional i.v. antimicrobial administration were associated with reduced post operative performance. Marked pannus, regional i.v. antimicrobial administration and duration of systemic antimicrobial administration were associated with a group combining nonsurviving animals and those with reduced post operative performance.

Conclusions: Endoscopic surgery makes a valuable contribution to the management of synovial contamination and infection.

Potential relevance: The information obtained from and therapeutic options offered by endoscopy justify its early use in cases of synovial contamination and infection.
Differences in polymorphonucleocyte function and local inflammatory response between horses and ponies
Authors: WILMINK J. M. , VEENMAN J. N. , van den BOOM R. , RUTTEN V. P. M. G. , NIEWOLD T. A. , BROEKHUISEN‐DAVIES J. M. , LEES P. , ARMSTRONG S. , van WEEREN P. R. , BARNEVELD A.
Published: April 2007

Reasons for performing study: Wound healing proceeds faster in ponies than in horses and complications during healing, such as wound infection, occur less frequently in ponies. Earlier studies suggested that this difference might be related to differences in the initial post traumatic inflammatory response.

Hypothesis: That polymorphonuclear leucocyte (PMN) function and profiles of humoral factors in local inflammatory processes are different in horses and ponies.

Methods: PMNs were isolated from venous blood of horses and ponies. Chemotaxis and reactive oxygen species (ROS) production was determined. Tissue cages were implanted in limbs and necks of horses and ponies and injected with carrageenan and, 3 weeks later, with LPS. In sequential samples of inflammatory exudate, the numbers of macrophages and PMNs and the production of PGE2, TNFα, IL‐1, IL‐6 and chemoattractants were determined.

Results: In vitro ROS production of PMNs was significantly higher in ponies than in horses, whereas in vitro PMN chemotaxis was significantly lower in ponies. In the tissue cages for both stimuli, the production of IL‐1 and chemoattractants was significantly higher in ponies than in horses and remained so towards the end of the observation period in ponies.

Conclusions: This study demonstrated a higher production of various inflammatory mediators by pony leucocytes. Despite the lower in vitro chemotaxis of pony PMNs, this higher in vivo production resulted in a stronger initial inflammatory response in ponies, as has been reported in studies on wound healing, through the attraction of leucocytes and triggering of the production of other cytokines. A stronger initial inflammation may promote healing by more rapid elemination of contaminants and earlier transition to repair.

Potential relevance: Modulation of the initial inflammatory response might therefore be a valid option for therapeutic intervention in cases of problematic wound healing. Further, the intraspecies differences in leucocyte function may have an impact on many fields in equine medicine.
Ovarian function and morphology in the mare after multiple follicular punctures
Authors: BØGH I. B. , BRINK P. , JENSEN H. E. , LEHN‐JENSEN H. , GREVE T.
Published: April 2007

Reasons for performing study: In the mare, ultrasound‐guided transvaginal oocyte recovery and transfer might offer away to circumvent the demanding procedures ofin vitroembryo production. Before clinical application, the possible consequences for subsequent fertility have to be considered.

Objectives: To examine ovarian function and morphology in mares after repeated follicular punctures.

Methods: A total of 14–26 follicular puncture sessions were conducted on each of 4 Norwegian pony mares overa period of 8 years. The ovaries of these mares were recovered by bilateral ovariectomy or atpost mortemand subjected to macroscopic inspection and histology. For comparison, ovaries were collected from 7 nonaspirated control mares and processed for histology.

Results: In all experimental mares, ovarian function, defined as the ability regularly to ovulate preovulatory follicles and developcorpora lutea, remained normal during their last breeding season. Gross examination and histology showed that normal follicular andcorpus luteumdevelopment was accompanied by the formation of condensed repa rative fibrosis and normal local haemosiderosis of the ovarian stroma in all experimental mares. In one mare, an ovary contained several foci of chronic apostematous oophoritis, while a cystic structure lined with a single layer of epithelial‐like cells and surrounded by a cartilaginous capsule was present in the other ovary.

Conclusions and potential relevance: Repeated follicular aspirations do not hamper future folliculogenesis, ovulation andcorpus luteumformation. However, ovarian puncture induces reparative fibrosis in the ovarian stroma and involves a risk of inducing abscess formation within the ovarian tissue which may impair fertility.
Changes in nasal mucosal innervation in horses with grass sickness
Authors: PRINCE D. , CORCORAN B. M. , MAYHEW I. G.
Published: April 2007

Reasons for performing study: Equine grass sickness is a dysautonomia characterised by widespread destruction of autonomic ganglia, resulting in the clinical signs of dysphagia, constipation, profuse sweating, tachycardia, rhinitis sicca and high mortality rate. Rhinitis sicca is a common finding in horses with the chronic form and we have postulated that alterations in autonomic innervation of the nasal mucosa might underlie this clinical presentation.

Objectives: In this study, the expression and distribution of nerve fibres immunoreactive for calcitonin gene‐related peptide (CGRP), substance P (SP), the general neuronal marker protein gene‐product 9.5 (PGP 9.5; ubiquitin) and the intermediate neurofilaments (PAN‐N; neurofilaments L, M and H) in the nasal mucosa of normal horses (n = 10) and horses with EGS (n = 18; acute n = 8, subacute n = 3, chronic n = 7) was assessed.

Methods: Innervation density and distribution was investigated in the different groups using standard immunohistochemical techniques.

Results: Significant differences were noted when comparing the density and distribution of nerve fibres immunoreactive for PGP 9.5 and PAN‐N, with PGP 9.5 consistently giving better staining in all groups and at all sites in the nasal mucosa. An apparent increase in the density of innervation was noted for acute vs. normal cases. A significant reduction in the density of innervation was noted only with PAN‐N when comparing normal horses and acute cases with the chronic group (P<0.05). CGRP and SP immunoreactive nerve fibres were typically most abundant in the epithelial and subepithelial layers, but the quality of staining and nerve fibre density was greater for SP, achieving significant difference in several comparisons. The density of innervation for SP was significantly reduced in the chronic group compared to the normal and acute groups (P<0.01). A significant decrease was noted for CGRP only for the acute and chronic groups (P<0.05).

Conclusions: These results demonstrate a reduction in the expression of the sensory neuropeptides in nasal mucosal innervation as a consequence of equine dysautonomia, and may underlie the clinical presentation of rhinitis sicca noted with this disease.

Potential relevance: Nasal biopsy may be of use in antemortem diagnosis of grass sickness and identification of mucosal denervation; and might also be useful in the treatment of rhinitis in EGS cases.
Clostridial myonecrosis in horses (37 cases 1985–2000)
Authors: PEEK S. F. , SEMRAD S. D. , PERKINS G. A.
Published: April 2007

Reasons for performing study: Previous reports of clostridial myonecrosis have either focused on individual case reports or have been small retrospective studies reporting very high mortality rates.

Objectives: The objective of this study was to describe the outcome of cases of clostridial myonecrosis submitted to 2 referral equine hospitals in the United States over a 15 year period.

Methods: A retrospective study of case material selected on the basis of positiveClostridiumspp. culture or the identification ofClostridiumspp. by specific fluorescent antibody testing from soft tissue wounds was performed at Cornell and Wisconsin.

Results: 37 cases of clostridial myonecrosis were documented. Twenty‐seven horses survived, 8 were subjected to euthanasia and 2 died during treatment for an overall survival rate of 73%. Twenty‐five cases (68%) were associated withClostridium perfringensalone, 6 cases (16%) withCl. septicumalone, 4 cases with mixed clostridial infections (11%), 1 case withCl. sporogenesand 1 with an unspeciatedClostridiumspp. The highest survival rate of 81% was docum ented for those cases from whichCl. perfringensalone was isolated. The most common antecedent condition prior to referral was colic. The myonecrotic lesion occurred within 6–72 h of a soft tissue injection in 34 cases but was associated with a wound or laceration in the remaining 3 cases. Of the 34 cases associated with recent injections, 24 were associated with i.m. injections in the cervical region, 4 in thesemimembranosus/semitendinosusregion, 3 in the gluteal region, 2 with perivascular leakage of drugs administered into the jugular vein and 1 case developed simultaneously in the gluteal and neck region following injections at both sites.

Conclusions: Clostridial myonecrosis can occur following the i.m. or inadvertent perivascular administration of a wide variety of commonly administered drugs. It is most common in the neck musculature. Aggressive treatment can be associated with survival rates of up to 81% for cases due toCl. perfringensalone. Survival rates for otherClostridialspp. tend to be lower.

Potential relevance: A combination of high dose i.v. antibiotic therapy and surgical fenestration/debridement is the best approach to cases of clostridial myonecrosis. With rapid diagnosis and therapeutic intervention, horses may have up to an 81% chance of survival.
Pharmacokinetics of fentanyl following intravenous and transdermal administration in horses
Authors: MAXWELL L. K. , THOMASY S. M. , SLOVIS N. , KOLLIAS‐BAKER C.
Published: April 2007

Reasons for performing study: Although fentanyl has been reported to cause CNS excitation in horses, a transdermal therapeutic system (TTS) containing this mu agonist has recently been used empirically in equine medicine to treat moderate to severe pain. A better understanding of the disposition of fentanyl following transdermal administration would facilitate the clinical use of TTS fentanyl to obtain analgesia in horses.

Objectives: To determine the pharmacokinetics of fentanyl following i.v. and TTS patch administration in healthy, mature horses and to evaluate the tolerance of horses to TTS fentanyl administration.

Methods: The pharmacokinetics of fentanyl in serum were assessed following a single i.v. dose, a single TTS dose, and multiple TTS doses in 6 healthy horses. Physical examinations, haematology and serum biochemistry analyses during transdermal fentanyl application were then performed to determine tolerance of continuous fentanyl administration.

Results: Fentanyl was very rapidly and completely absorbed following a single TTS dose. Mean serum fentanyl concentrations consistent with analgesia in other species were reached by 1 h and maintained until 32 h after patch application. Similar steady state serum concentrations were obtained when multiple doses of TTS fentanyl were administered every 48 or 72 h over 8 or 9 days, with less fluctuation in serum concentrations during the 48 h dosing interval. Three horses exhibited brief (<12 h) episodes of increased body temperature; however, transdermal fentanyl administrations were not associated with other significant changes in haematology and biochemistry panels or physical examination findings.

Conclusions and potential relevance: Although the pharmacodynamics of fentanyl have not been investigated fully in horses, transdermally‐administered fentanyl exhibited a favourable pharmacokinetic profile without clinically relevant side effects and may be a useful analgesic in equine patients.
Airway inflammation and mucus in two age groups of asymptomatic well‐performing sport horses
Authors: GERBER V. , ROBINSON N. E. , LUETHI S. , MARTI E. , WAMPFLER B. , STRAUB R.
Published: April 2007

Reasons for performing study: Horses housed in conventional stable environments are exposed to high dust loads. Longterm exposure to inhaled dust may lead to subclinical airway disease.

Hypotheses: Airway inflammation and mucus accumulation are 1) common in asymptomatic well‐performing sport horses, 2) increased in older compared to younger individuals and 3) correlated.

Methods: Mucus quantity and quality (endoscopic scoring) and BALF differential cytology were assessed in 13 younger horses (mean age 5 years) and 13 older horses (mean age 15 years), which had no historical or clinical evidence of lower airway disease, were performing well and were housed permanently in a conventional stable environment.

Results: 1) Airway inflammation and/or mucus accumulation were very common. All sport horses showed evidence of subclinical inflammatory airway disease (IAD). 2) Older horses, having been exposed for 10 more years to a conventional stable environment, did not show increased subclinical airway inflammation or mucus accumulation. The only differences between the age groups were increased BALF total and lymphocyte cell counts in the younger horses. 3) Mucus quantity and quality scores were not significantly correlated with each other or with BALF neutrophil percentages and absolute numbers.

Conclusions: Although clinically healthy and performing well, all of the examined horses housed in a conventional stable environment showed evidence of IAD. The degree of IAD was not increased in older horses that had not developed clinical signs.

Potential relevance: The effect of subclinical degrees of IAD on performance in dressage and show jumping should be investigated further to better understand the clinical significance of IAD in sport horses.
Comparison of hamster and pony challenge models for evaluation of effect of antigenic drift on cross protection afforded by equine influenza vaccines
Authors: DALY J. M. , YATES P. J. , BROWSE G. , SWANN Z. , NEWTON J. R. , JESSETT D. , DAVIS‐POYNTER N. , MUMFORD J. A.
Published: April 2007

Reasons for performing study: Vaccination and challenge studies in ponies are the most relevant experimental system for predicting whether strains included in equine influenza vaccines are relevant, but they are difficult to perform.

Objectives: In order to investigate the feasibility of using a small animal model, results of a cross‐protection study in hamsters were compared with those from a previous pony challenge experiment.

Methods: Animals were immunised with inactivated vaccines containing one of 4 strains of equine influenza A H3N8 subtype virus isolated over a 26 year period (1963 to 1989), then challenged with a 1989 strain.

Results: Although there was no significant difference in titres of excreted virus between groups of vaccinated ponies, hamsters immunised with heterologous strains had significantly higher virus titres in the lung than hamsters vaccinated with the homologous strain. In both ponies and hamsters, the number of animals excreting virus was greater the earlier the isolation date of the vaccine strain, although this was only significant in the hamster study.

Conclusions: Despite differences, the overall conclusion of both the pony and hamster models was that heterologous vaccines may be less effective than homologous vaccines at preventing virus excretion.

Potential relevance: Further validation is required, but the hamstermodel shows potential for preliminary assessment of the effects of antigenic drift on vaccine efficacy.
The effects of local anaesthetic solution in the navicular bursa of horses with lameness caused by distal interphalangeal joint pain
Authors: SCHUMACHER JOHN , SCHUMACHER JIM , GILLETTE R. , DEGRAVES F. , SCHRAMME M. , SMITH R. , PERKINS J. , COKER M.
Published: April 2007

Reasons for performing study: Analgesia of the palmar digital (PD) nerves has been demonstrated to cause analgesia of the distal interphalangeal (DIP) joint as well as the sole. Because the PD nerves lie in close proximity to the navicular bursa, we suspected that that analgesia of the navicular bursa would anaesthetise the PD nerves, which would result in analgesia of the DIP joint.

Objectives: To determine the response of horses with pain in the DIP joint to instillation of local anaesthetic solution into the navicular bursa.

Methods: Lameness was induced in 6 horses by creating painful synovitis in the DIP joint of one forefoot by administering endotoxin into the joint. Horses were videorecorded while trotting, before and after induction of lameness, at three 10 min intervals after instilling 3.5 ml local anaesthetic solution into the navicular bursa and, finally, after instilling 6 ml solution into the DIP joint. Lameness scores were assigned by grading the videorecorded gaits subjectively.

Results: At the 10 and 20 min observations, median lameness scores were not significantly different from those before administration of local anaesthetic solution into the navicular bursa (P≥0.05), although lameness scores of 3 of 6 horses improved during this period, and the 20 min observation scores tended toward significance (P = 0.07). At the 30 min observation, and after analgesia of the DIP joint, median lameness scores were significantly improved (P≤0.05).

Conclusions: These results indicate that pain arising from the DIP joint can probably be excluded as a cause of lameness, when lameness is attenuated within 10 mins by analgesia of the navicular bursa.

Potential relevance: Pain arising from the DIP joint cannot be excluded as a cause of lameness when lameness is attenuated after 20 mins after analgesia of the navicular bursa.
Homeostasis of intracellular Ca2+ in equine chondrocytes: response to hypotonic shock
Authors: WILKINS R. J. , AFAIRFAX T. P. , DAVIES M. E. , MUZYAMBA M. C. , GIBSON J. S.
Published: April 2007

Reasons for performing study: Ca2+ homeostasis in articular chondrocytes affects synthesis and degradation of the cartilage matrix, as well as other cellular functions, thereby contributing to joint integrity. Although it will be affected by mechanical loading, the sensitivity of intracellular Ca2+ concentration ([Ca2+]i) in equine articular chondrocytes to many stimuli remains unknown.

Hypothesis: An improved understanding of Ca2+ homeostasis in equine articular chondrocytes, and how it is altered during joint loading and pathology, will be important in understanding how joints respond to mechanical loads.

Methods: [Ca2+]i was determined using the fluorophore fura‐2. We examined the effects of hypotonic shock, a perturbation experienced in vivo during mechanical loading cycles. We used inhibitors of Ca2+ transporters to ascertain the important factors in Ca2+ homeostasis.

Results: Under isotonic conditions, [Ca2+]i was 148 ± 23 nmol/l, increasing by 216 ± 66 nmol/l in response to reduction in extracellular osmolality of 50%. Resting [Ca2+]i, and the increase following hypotonic shock, were decreased by Ca2+ removal; they were both elevated when extracellular [Ca2+] ([Ca2+]o) was raised or following Na+ removal. The hypotonicity‐induced rise in [Ca2+]i was inhibited by exposure of cells to gadolinium (Gd3+; 10 μmol/l), an inhibitor of mechanosensitive channels. [Ca2+]i was also elevated following treatment of cells with thapsigargin (10 μmol/l), an inhibitor of the Ca2+ pump of intracellular stores.

Conclusions: A model is presented which interprets these findings in relation to Ca2+ homeostasis in equine articular chondrocytes, including the presence of mechanosensitive channels allowing Ca2+ entry, a Na+/Ca2+ exchanger for removal of intracellular Ca2+ and intracellular stores sensitive to thapsigargin.

Potential relevance: A more complete understanding of Ca2+ homeostasis in equine chondrocytes may allow development of future therapeutic regimes to ameliorate joint disease.
A survey of equine abortion, stillbirth and neonatal death in the UK from 1988 to 1997
Authors: SMITH K. C. , BLUNDEN A. S. , WHITWELL K. E. , DUNN K. A. , WALES A. D.
Published: April 2007

Reasons for performing study: A detailed review of laboratory records for equine abortion is fundamental in establishing current disease trends and suggesting problems important for further research.

Objectives: To review the causes of abortion and neonatal death in equine diagnostic submissions to the Animal Health Trust over a 10 year period.

Methods: The diagnoses in 1252 equine fetuses and neonatal foals were reviewed and analysed into categories.

Results: Problems associated with the umbilical cord, comprising umbilical cord torsion and the long cord/cervical pole ischaemia disorder, were the most common diagnoses (38.8%: 35.7% umbilical cord torsion and 3.1% long cord/cervical pole ischaemia disorder). Other noninfective causes of abortion or neonatal death included twinning (6.0%),intrapartumstillbirth (13.7%) and placentitis, associated with infection (9.8%).E. coliandStreptococcus zooepidemicuswere the most common bacteria isolated. Neonatal infections not associated with placentitis accounted for 3.2% of incidents; and infections with EHV‐1 or EHV‐4 for 6.5%.

Conclusions: Definitive diagnosis of equine abortion is possible in the majority of cases where the whole fetus and placenta are submitted for examination.

Potential relevance: Given the high incidence of umbilical cord torsion and related problems as causes of abortion in UK broodmares, more research on factors determining umbilical cord length and risk of torsion is essential.
Evaluation of Carolina Rinse solution as a treatment for ischaemia reperfusion of the equine jejunum
Authors: Dabareiner R. M. , II N. A. White , Donaldson L.
Published: April 2007

Reasons for performing study: Ileus and peritoneal adhesions are the most common complications following surgery for small intestinal obstruction. Carolina Rinse (CR) has been shown to decrease reperfusion injury in intestine and other organs.

Hypothesis: CR decreases intestinal inflammation and subsequent scarring associated with reperfusion injury.

Methods: CR was infused intra‐arterially and applied topically just prior to reperfusion in jejunum exposed to experimental ischemia. Vascular permeability, neutrophil accumulation and serosal scarring were compared in treated and untreated intestine.

Resultls: CR maintained a normal osmotic reflection coefficient and decreased migration of neutrophils into the serosa during reperfusion. After 10 days, treated intestine was normal in appearance with a trend toward less serosal scarring and fibroblast proliferation. There was a significant decrease in fibroplasia at biopsy sites in treated intestine.

Conclusions: Arterial perfusion combined with topical application of CR during jejunal ischaemia decreases immediate reperfusion injury and limits post operative scarring.

Potential relevance: CR should be used as a local perfusate rather than a systemic treatment; it may best be applied topically and intraluminally to avoid damaging mesenteric arteries. CR should be considered an adjunct treatment as part of overall surgical management and post operative care.
Long‐term survey of laryngoplasty and ventriculocordectomy in an older, mixed‐breed population of 200 horses. Part 1: Maintenance of surgical arytenoid abduction and complications of surgery
Authors: DIXON P. M. , McGORUM B. C. , RAILTON D. I. , HAWE C. , TREMAINE W. H. , DACRE K. , McCANN J.
Published: April 2007

Reasons for performing study: Laryngoplasty (LP) is currently the most common surgical treatment for equine laryngeal paralysis, however, there have been no reports quantifying the degree of retention of arytenoid abduction following L P. ADitionally, the complications of LP have been poorly documented.

Objectives: To record the degree of arytenoid abduction retention following LP and to accurately document all complications of surgery.

Methods: A study (1986–1998) of 200 horses of mixed breed and workload, median age 6 years (prospective 136 cases and retrospective 64 cases) undergoing LP (using 2 stainless steel wires) and combined ventriculocordectomy was undertaken; 198 owners completed questionnaires, a median of 19 months following surgery. The degree of arytenoid abduction achieved was endoscopically, semi‐quantitatively evaluated using a 5‐grade system, at 1 day, 7 days, and 6 weeks after surgery.

Results: On the day following LP, 62% of horses had good (mediangrade2) arytenoid abduction, 10% had excessive (grade1), and 5% had minimal (grade4) abduction (overall ‐ mediangrade2). Due to progressive loss of abduction, moderate (mediangrade3, range 1–5) abduction was present overall at 1 and 6 weeks after LP. Further surgery was required to re‐tighten prostheses in 10% of cases with excessive loss of abduction, or to loosen prostheses in 7% of horses which had continuing high levels of LP abduction and significant post operative dysphagia. LP wound problems (mainly seromas and suture abscesses) were reported to last <2 weeks in 9% of cases, <4 weeks in 4% and >4 weeks in 4%. The (partially sutured) laryngotomy wounds discharged post operatively for <2 weeks in 22% of cases, <4 weeks in 7% and for >4 weeks in 2%. Coughing occurred at some stage post operatively in 43% of cases and its presence correlated significantly with the degree of surgical arytenoid abduction. This coughing occurred during eating in 24% of cases and was not associated with eating (or dysphagia) in the other 19% of cases. Chronic (>6 months duration) coughing occurred in 14% of cases, but appeared to be due to intercurrent pulmonary disease in half of these horses.

Conclusions: Suturing the cricotracheal membrane allows most laryngotomy wounds to heal quickly. Laryngoplasty wound problems were of little long‐term consequence when stainless steel wire prostheses were used.

Potential relevance: A significant loss of LP abduction occurs in most horses in the 6 weeks following surgery and efforts should be made to find ways to prevent such loss. However, excessive LP abduction is associated with post operative dysphagia and coughing.
The application of a scintigraphic grading system to equine tibial stress fractures: 42 cases
Authors: RAMZAN P. H. L. , NEWTON J. R. , SHEPHERD M. C. , HEAD M. J.
Published: April 2007

Reasons for performing study: Tibial stress fractures are an important cause of lameness in the Thoroughbred racehorse. While it is recognised that these injuries can vary in clinical presentation and radiographic or scintigraphic appearance, little has been done to quantify lesion severity. By contrast the scintigraphic grading of tibial stress fractures in human athletes is widely reported and assists in the selection of appropriate management regimes.

Objectives: To determine the relationship between scintigraphic grade, clinical severity and radiographic appearance of tibial stress fractures.

Methods: The current study involved the retrospective analysis of records from 42 Thoroughbreds with abnormal tibial scintigraphic activity.

Results: There was a significant association between lesion site and scintigraphic grade and good correlation of scintigraphic scoring between investigators. No significant association was found between scintigraphic grade and either radiographic grade or degree of lameness.

Conclusions: The study confirmed that radiographic appearance is an unreliable measure of clinical severity or stage of progression of lesions. The scintigraphic grading system used in the study was not of use in defining stress fracture severity in the equine tibia.

Potential relevance: Despite this finding, there is clearly a need for prospective investigations to explore the potential for targeted management regimes for tibial injuries based on lesion site or clinical criteria.