bluuebunny/crossref_metadata_2025_split huggingface dataset:
Collateral desmitis of the distal interphalangeal joint in 18 horses (2001–2002)
Authors: Dyson S. J. , Murray R. , Schramme M. , Branch M. 
Published: April 2007

Summary Reasons for performing study: There have been no previously published case series of horses examined using either scintigraphy or MRI to diagnose collateral ligament injuries not detectable using ultrasonography or radiography, nor have other concurrent soft tissue lesions been described. Objectives: To describe the clinical features of horses with desmitis of the collateral ligaments of the distal interphalangeal (DIP) joint and to evaluate the results of radiographic, ultrasonographic, scintigraphic and magnetic resonance imaging (MRI) examinations. Methods: Horses were examined between January 2001 and January 2003 and were selected for inclusion in the study if there was unequivocal evidence of collateral desmitis of the DIP joint based on ultrasonography or MRI. Subject details, case history, results of clinical examination and responses to local analgesic techniques were reviewed. The results of radiographic, ultrasonographic, scintigraphic and MRI examinations were assessed. Results: Eighteen horses were identified with desmitis of a collateral ligament of the DIP joint, 3 horses (Group I) based on ultrasonography alone, 7 (Group II) with positive ultrasonographic and magnetic resonance images and 8 (Group III) with no lesion detectable using ultrasonography, but lesions identified using MRI. Seventeen horses had forelimb injuries and one a hindlimb injury. The medial collateral ligament was injured most frequently (13 horses). In the majority of horses, no localising clinical signs were seen. Lameness was invariably worse in circles compared with straight lines. Lameness was improved by palmar digital analgesia in 16 horses (87%), but only 6 were nonlame. Intra‐articular analgesia of the DIP joint produced improvement in lameness in 6/15 horses (40%). In 16 horses, no radiographic abnormality related to the DIP joint or collateral ligament attachments was identified. Eight of 14 horses (57%) had focal, moderately or intensely increased radiopharmaceutical uptake (IRU) at the site of insertion of the injured collateral ligament on the distal phalanx. Alteration in size and signal in the injured collateral ligament was identified using MRI. In addition, 5 horses had abnormal mineralisation and fluid in the distal phalanx at the insertion of the ligament. Eleven horses had concurrent soft tissue injuries involving the deep digital flexor tendon, distal sesamoidean impar ligament, navicular bursa or collateral ligament of the navicular bone. Conclusions and potential relevance: Collateral desmitis of the DIP joint should be considered as a cause of foot lameness. Although some injuries are detectable ultrasonographically, false negative results occur. Focal IRU at the ligament insertion on the distal phalanx may be indicative of injury in some horses. MRI is useful for both characterisation of the injury and identification of any concurrent injuries. Further follow‐up information is required to determine factors influencing prognosis.;
Equine laminitis: loss of hemidesmosomes in hoof secondary epidermal lamellae correlates to dose in an oligofructose induction model: an ultrastructural study
Authors: French K. R. , Pollitt C. C. 
Published: April 2007

Summary Reasons for performing study: Light microscopical studies show that the key lesion of laminitis is separation at the hoof lamellar dermal‐epidermal interface. More precise knowledge of the damage occurring in the lamellar basement membrane zone may result if laminitis affected tissue is examined with the transmission electron microscope. This could lead to better understanding of the pathogenesis of lesions and the means of treatment or prevention. Objectives: To investigate the ultrastructure of acute laminitis as disease of greater severity is induced by increasing oligofructose (OF) dosage. Methods: Three pairs of normal horses, dosed with OF at 7.5, 10 and 12.5 g/kg bwt via nasogastric intubation, developed laminitis 48 h later. Following euthanasia, their forefeet were processed for transmission electron microscopy. Lamellar basal cell hemidesmosome (HD) numbers and the distance between the basal cell plasmalemma and the lamina densa of the basement membrane were estimated and compared to control tissue. Results: Increasing OF dosage caused greater HD loss and more severe laminitis. The characteristic separation of the basement membrane, cytoskeleton failure and rounded basal cell nuclei results from combined HD dysassembly and anchoring filament failure. Conclusions: Without properly assembled HDs, dysadhesion between the lamina densa of the basement membrane (BM) and epidermal basal cells occurs, emphasising the fundamental importance of HDs in maintaining attachment at the lamellar interface. Medical conditions that trigger lamellar matrix metalloproteinase (MMP) activation and/or compromise entry of glucose into lamellar basal cells appear to promote loss and failure of HDs and, therefore, laminitis development. Potential relevance: A correlation between lameness severity and escalating loss of lamellar HDs now exists. Therapy aimed at protecting the lamellar environment from haematogenous delivery of MMP activators or from glucose deprivation may control laminitis development.
Hoof wall wound repair
Authors: Pollitt C. C. , Daradka M. 
Published: April 2007

Summary Reasons for performing study: Surgical stripping of the hoof wall results in a wound that heals remarkabley well. In contrast, lamellae recovering from laminitis are often deformed. Investigating lamellar wound healing may aid understanding of laminitis. Objectives: To document temporal changes in the lamellar basement membrane (BM), dermis and epidermis after surgery. Methods: Wall strips were made in the dorsal hoof wall midline of 6 mature horses. Immunohistochemistry was used to document changes in the basement membrane (BM) and detect proliferation of epidermal cells in lamellar tissues harvested at intervals. A conforming metal plate was screwed to the hoof wall to maintain alignment of the wound edges. Results: Wall stripping caused lamellar tips to snap and remain behind in the dermis along with the majority of the lamellar BM and some lamellar basal cells. Three days later the BM was intact and new lamellae had been reconstructed by proliferation of surviving epidermal cells. By 5 days the surface of the stripped zone was covered with yellow epidermis that subsequently thickened and hardened. Eventually the hoof wall deficit was replaced by new wall growing down from the coronet. The conforming metal plate and post operative analgesic ensured minimal lameness. Conclusions and potential relevance: In wall stripped lamellae the BM survives virtually intact and is used as a template for proliferating cells, from snapped‐off lamellar tips, to migrate and quickly achieve repair to near normality. In laminitis epidermal dysadhesion and lamellar BM destruction occurs and lack of a functional BM template may explain the prolonged and abnormal repair of affected lamellae.
Epidermal cell proliferation in the equine hoof wall
Authors: Daradka M. , Pollitt C. C. 
Published: April 2007

Summary Reasons for performing study: Current theories explaining how the hoof wall ‘grows’ and moves past the stationary distal phalanx are speculative and based on incomplete evidence. Movement in the lamellar region could occur by cell proliferation or an enzyme‐based remodelling process. Since laminitis pathogenesis appears to involve increased transcription and activation of enzymes normally involved in tissue remodelling, it is important to know precisely which process dominates the lamellar region of the hoof. Objectives: T o investigate epidermal cell proliferation in the equine hoof wall and calculate a proliferative index (PI) for the coronet, lamellae and toe. Methods: An analogue of thymidine, 5‐bromo‐2′‐deoxyuridine (BRdU), was infused i.v. into 5 ponies. After tissue harvesting, BRdU (and therefore basal cell proliferation) was detected immunohistochemically using mouse anti‐BRdU. PIs were calculated for the coronet and 10 levels of the dorsal hoof wall lamellae. Results: The highest PIs (mean ± s.e.) were in the coronet; 12.04%± 1.59 and proximal lamellae (7.13%± 1.92) and are therefore growth zones of the proximal hoof wall. PIs of more distal lamellae were 0.11%± 0.04 to 0.97%± 0.29; significantly lower (P = 0.05) than the lamellar growth zone. Conclusions: A 20‐fold PI decrease between proximal and more distal lamellae suggests that the majority of the normal lamellae are nonproliferative and their main function is to suspend the distal phalanx within the hoof capsule. Remodelling within the hoof wall epidermal lamellae, which must occur as the hoof wall moves past the stationary distal phalanx, is a process not requiring epidermal cell proliferation. Potential relevance: A hoof lamellar epidermis that remodels using the same MMPs involved in laminitis pathogenesis implies that laminitis is a normal process out of control. Understanding MMP control and how the normal lamellar epidermis achieves this will help in the development of better laminitis preventative and treatment strategies.
Horse‐level risk factors for fatal distal limb fracture in racing Thoroughbreds in the UK
Authors: PARKIN T. D. H. , CLEGG P. D. , FRENCH N. P. , PROUDMAN C. J. , RIGGS C. M. , SINGER E. R. , WEBBON P. M. , MORGAN K. L. 
Published: April 2007

SummaryReasons for performing study: Fractures below the level of the radius or tibia (distal limb fractures) are the most common cause of equine fatality on UK racecourses; however, little is known about their epidemiology or aetiology. Identification of risk factors could enable intervention strategies to be designed to reduce the number of fatalities.Objectives: To identify horse‐level risk factors for fatal distal limb fracture in Thoroughbreds on UK racecourses.Methods: A case‐control study design was used. Fractures in case horses were confirmed bypost mortemexamination and 3 matched uninjured controls were selected from the race in which the case horse was running. One hundred and nine cases were included and information was collected about previous racing history, horse characteristics and training schedules. Conditional logistic regression was used to identify the relationship between a number of independent variables and the likelihood of fracture.Results: Horses doing no gallop work during training and those in their first year of racing were at significantly increased risk of fracture on the racecourse. Case horses were also more likely to have trained on a sand gallop, i.e. a gallop described by trainers as being primarily composed of sand.Conclusions: Modifications to training schedules, specifically within the first year of racing, may have a large impact on the risk of fatal distal limb fracture on the racecourse. Horses should do some gallop work in training and our results suggest that the minimum distance galloped should be between 805‐2012 m (4‐10 furlongs)/week.Potential relevance: The information from this study can be used to alter training schedules in an attempt to reduce the incidence of fatal distal limb fracture in Thoroughbred racehorses. Training should include some gallop work, and further studies, recording the exact level of work, will help to identify an optimum range of training speeds and distances which will reduce the liklihood of catastrophic fracture on the racecourse.
Clinical anatomy of the equine sphenopalatine sinus
Authors: McCANN J. L. , DIXON P. M. , MAYHEW I. G. 
Published: April 2007

Summary Reasons for performing study: Disorders of the equine sphenopalatine sinus, including empyema and neoplasia, have been reported to cause damage to cranial nerves II and V. However, the clinical anatomy of these sinuses is not well described in horses. Objective: To examine the anatomy of the sphenopalatine sinuses in a range of equidae and, in particular, to examine the relationship of these sinuses to adjacent major nerves and vessels. Methods: The anatomy of the sphenoidal and palatine paranasal sinuses was examined in 16 equidae, primarily using transverse skull sections. Relevant structures were documented and photographed. Results: There was much variation between individual horses in sphenopalatine sinus anatomy. The sphenoidal sinuses were small in young horses and appeared to become larger and more complex with age. Variation was present in the extent that the sphenopalatine sinus extended into the basisphenoid bone. The septum dividing left and right sphenoidal sinuses was frequently not midline, but was intact in all cases. The sphenoidal and palatine sinuses communicated in most horses. In such cases, what could accurately be termed the (combined) sphenopalatine sinuses usually drained directly into the caudal maxillary sinuses. Additionally, in 5 out of 16 cases, some compartments of the sphenoidal sinus also drained into the ethmoidal sinus. The dorsal and lateral walls of the sphenoidal sinus were very thin and directly adjacent to cranial nerves II, III, IV, V and VI and major blood vessels. Conclusions: The equine sphenoidal and palatine sinuses are very variable in their anatomy, but are always in close proximity to multiple cranial nerves and major blood vessels. Potential relevance: Many cranial nerves and blood vessels could be damaged with disorders involving the sphenopalatine sinus, potentially causing major and variable neurological syndromes, haemorrhage and extension of sepsis.
Onset of puberty in pasture‐raised Thoroughbreds born in southern hemisphere spring and autumn
Authors: BROWN‐DOUGLAS C. G. , FIRTH E. C. , PARKINSON T. J. , FENNESSY P. F. 
Published: April 2007

Summary Reasons for performing study: There is little information on age, weight and time of year of puberty in Thoroughbred horses, and the interpretation of such data is difficult due to the wide variety of descriptions of the onset of puberty. Objectives: To examine the age, bodyweight and date of onset of puberty in Thoroughbreds born in spring and autumn. Methods: Bodyweight data and blood samples were collected in 59 pasture‐raised Thoroughbred horses. Five autumn‐born and 18 spring‐born colts and 3 autumn‐born and 33 spring‐born fillies were examined from birth to age 13 and 17 months. A testosterone concentration >2 s.d. above the baseline concentration was indicative of onset of puberty in colts; and progesterone concentration >2 ng/ml and at least 3 times greater than the previous progesterone concentration was indicative of a first ovulation in fillies. Results: Spring‐born fillies and colts were older and heavier than autumn‐born fillies and colts at puberty. The age at onset of puberty in spring‐ and autumn‐born foals was 291‐408 days and 212‐270 days, respectively. The weight at puberty in spring‐born foals was 302‐409 kg, and in autumn‐born foals was 277‐344 kg. However, the mean date at onset of puberty was not significantly different between spring‐ and autumn‐born horses, with puberty occurring in October (New Zealand spring). Conclusions and potential relevance: Seasonal changes in photoperiod affect the timing of onset of puberty, provided a minimum threshold bodyweight has been reached. Springborn horses reached this threshold weight during the winter months and remained reproductively inactive until after the stimulus of increasing day‐length occurred. The autumn‐born horses reached the threshold weight to support puberty at the same time as stimulatory photoperiod and, therefore, reached puberty significantly younger and lighter than the spring‐born horses.
Routine castration in 568 draught colts: incidence of evisceration and omental herniation
Authors: SHOEMAKER R. , BAILEY J. , JANZEN E. , WILSON D. G. 
Published: April 2007

Summary Reasons for performing study: Castration is one of the most common routine surgical procedures performed in the horse, from which a number of potential complications can arise. We undertook a prospective evaluation of short‐term complications associated with castration of draught colts over a 3‐year period (1998–2000). Objectives: To compare castration complications in a large number of draught foals with previously published literature. Methods: Five hundred and sixty‐eight draught colts, age 4 or 5 months, were castrated in field conditions. Foals were observed for complications for 24 h post operatively. Results: There was no significant difference in complication rates between open and closed surgical techniques. Inguinal/scrotal hernia rate was 4.6% (26/568) prior to surgery, and evisceration of the small intestine occurred in 4.8% (27/568). Foals observed to eviscerate underwent immediate surgical correction with an overall survival rate of 72.2% (13/18). Omental herniation was seen in 2.8% (16/568) of colts. Conclusions: This study showed no difference between the closed and open techniques of castration and the rate of omental herniation or evisceration. The evisceration rate in combination with the omental and presurgical herniation rates approached 12.2%, which is high enough to warrant further examination. Potential relevance: Future investigation should help to assess predisposing factors for evisceration. Regardless of the technique employed, herniation appears to pose a significant risk to draught foals undergoing castration.
Osteoarthritis of the talocalcaneal joint in 18 horses
Authors: SMITH R. K. W. , DYSON S. J. , SCHRAMME M. C. , HEAD M. J. , PAYNE R. J. , PLATT D. , WALMSLEY J. 
Published: April 2007

Summary Reasons for performing study: Talocalcaneal osteoarthritis (TO) is an uncommon cause of moderate to severe hindlimb lameness, on which only isolated case reports have been published to date. Objectives: To review the clinical features of TO and determine optimal methods for diagnosis, management and prognosis. Methods: The case records from 4 referral centres of 18 horses showing hindlimb lameness considered, as a result of clinical investigation, to be caused by TO, were reviewed. Results: TO affected mature sports and pleasure horses (age 7‐16 years) and caused moderate to severe lameness, usually of sudden onset with no obvious inciting cause. There were few localising signs, other than worsening of lameness by hock flexion. Tarsocrural joint analgesia produced improvement in lameness in 6/11 horses (55%) and perineural analgesia of the tibial and fibular nerves complete soundness in 6/14 horses (43%) in which it was performed; 7/14 horses (50%) showed a further substantial improvement. Radiological findings included subchondral bone lysis and sclerosis and irregular joint space width, seen most obviously in a lateromedial view. Nuclear scintigraphy revealed marked uptake of radiopharmaceutical predominantly plantaromedially in the region of the talus in the 7 horses in which it was performed. Fourteen horses were treated conservatively with box‐ or pasture‐rest, with or without intra‐articular corticosteroids, hyaluronic acid or polysulphated glycosaminoglycan, and all remained lame. Intra‐articular corticosteroids appeared to have no effect in any horse. Of 10 horses receiving conservative management only, 6 were subjected to euthanasia, 3 were retired and 1 remained in light work, but was still lame. Two horses treated by either partial tibial and fibular neurectomy or subchondral forage failed to regain soundness and were retired. Six horses were treated by surgical arthrodesis of the talocalcaneal joint with 2 or three 5.5 mm AO screws introduced obliquely across the joint from the plantarolateral aspect of the calcaneus, which resulted in improvement in lameness in all cases. Conclusions: Osteoarthritis of the talocalcaneal joint causes acute onset severe lameness, but clinical findings and diagnostic analgesia often fail to identify precisely the site of pain. Consistent radiographic changes suggested TO was contributing to the lameness and this diagnosis was supported by nuclear scintigraphy. The poor success of conservative treatment (including intra‐articular medication) suggests that surgical arthrodesis is the treatment of choice, although the prognosis is still poor for a return to full soundness. Potential relevance: The clinical features described should facilitate more accurate diagnosis and prognosis. A novel surgical treatment is described which appears to offer significant improvement in the lameness. Further work is necessary to determine the causes of this condition and more effective management.
Cardiopulmonary effects and pharmacokinetics of i.v. dexmedetomidine in ponies
Authors: BETTSCHART‐WOLFENSBERGER R. , FREEMAN S. L. , BOWEN I. M. , ALIABADI F. S. , WELLER R. , HUHTINEN M. , CLARKE K. W. 
Published: April 2007

SummaryReasons for performing study: Currently available sedatives depress cardiopulmonary function considerably; therefore, it is important to search for new, less depressive sedatives. The study was performed to assess duration and intensity of cardiopulmonary side effects of a new sedative, dexmedetomidine (DEX), in horses.Objectives: To study pharmacokinetics and cardiopulmonary effects of i.v. DEX.Methods: Pharmacokinetics of 3.5 μg/kg bwt i.v. DEX were studied in a group of 8 mature (mean age 4.4 years) and 6 old ponies (mean age 20 years). Cardiopulmonary data were recorded in mature ponies before and 5, 10, 20, 30, 45 and 60 mins after administration of DEX 3.5 μg/kg bwt i.v. Data were analysed using ANOVA for repeated measures, and where appropriate Dunnett'sttest was used to detect differences from resting values (P<0.05).Results: Within 2 h after DEX administration, plasma levels were beyond limits of quantification (0.05 ng/ml). Mean values for kinetic parameters for mature and old ponies were: Cmax (ng/ml) 4.6 and 3.8, t1/2(min) 19.8 and 28.9 and AUC (ng.min/ml) 34.5 and 44.3, respectively. Heart rate, central venous pressure, pulmonary artery pressure and pulmonary capillary wedge pressure did not change significantly compared to presedation values throughout the 60 min observation period. Compared to presedation values, stroke volume and mixed venous PO2were reduced for the first 5 mins, paralleled by an increase in systemic and pulmonary vascular resistance. Cardiac index was reduced for the first 10 mins, arterial blood pressures at 20, 30 and 45 mins and respiratory rate throughout the 60 min observation period, but no change in arterial PO2or PCO2occurred.Conclusions: DEX administration i.v. causes similar cardiopulmonary changes to those caused by other alpha‐2adrenoceptor agonists, but of very short duration. DEX is redistributed particularly rapidly.Potential relevance: DEX might be safer for sedation of horses because of its very short‐lasting cardiopulmonary side effects. For long duration sedation, its kinetics favour its use as a continuous infusion.