bluuebunny/crossref_metadata_2025 huggingface dataset:
Polysaccharide storage myopathy in theM. longissimus lumborumof showjumpers and dressage horses with back pain
Authors: QUIROZ‐ROTHE E. , NOVALES M. , AGUILERA‐TEJERO E. , RIVERO J. L. L.
Published: April 2007

This study was designed to investigate whether horses with clinical signs of back pain due to suspected soft tissue injuries were affected by polysaccharide storage myopathy (PSSM). Diagnosis of PSSM in muscle biopsies obtained from theM. longissimus lumborumof 5 showjumpers and 4 dressage horses with a history of back pain is reported.M. longissimus lumborumbiopsies of these horses were characterised histopathologically and in 3/9 cases also by electron microscopy. Observations were compared withM. gluteusbiopsies of the same horses, and withM. gluteusbiopsies obtained from 6 Standardbreds with recurrent exertional rhabdomyolysis and from 6 healthy trotters.M. longissimusbiopsies from horses with back pain showed pathognomonic signs of PSSM, i.e. high glycogen and/or abnormal complex amylase‐resistant polysaccharide deposits. Similar features were found inM. gluteusbiopsies of the same horses. Sections of horses with rhabdomyolysis had increased PAS stain when compared with healthy horses, but did not show amylase‐resistant material. Qualitative observations were corroborated by quantitative histochemistry (optical densities) of sections stained with PAS and amylase PAS. This study demonstrated the presence of PSSM in theM. longissimusof showjumpers and dressage horses with back pain and indicates that epaxial muscle biopsy is an option in diagnosing back problems in horses when clinical examination and imaging techniques do not provide a precise diagnosis.
Ventriculocordectomy reduces respiratory noise in horses with laryngeal hemiplegia
Authors: BROWN J. A. , DERKSEN F. J. , STICK J. A. , HARTMANN W. M. , ROBINSON N. E.
Published: April 2007

Reasons for performing study: Show and performance horse with laryngeal hemiplegia (LH) often present for excessive respiratory noise ratherthan significant exercise intolerance. Therefore, the goal of surgery in these horses is to reduce re spiratory noise but there are no quantitative studies evaluating the effect of any upper‐airway surgery in LH‐affected horses.

Objective: To determine whether bilateral ventriculocordectomy (VC) reduces respiratory noise in exercising horses with laryngeal hemiplegia.

Methods: Six Standardbred horses with normal upperairways were used in this study. Respiratory sounds and inspiratory trans‐upper airway pressure (Pui) were measured in all horses before and after induction of LH, and 30, 90 and 120 days after VC. In horses with LH, spectrogram analysis revealed 3 inspiratory sound formants centred at approximately 400, 1700 and 3700 Hz. Inspiratory sound levels (SL) and the sound intensity of the 3 inspiratory formants (F1, F2, F3respectively) were measured using a computer‐based sound analysis programme.

Results: In LH‐affected horses, Pui, inspiratory SL and the sound intensity of F2and F3were significantly increased compared to baseline values. At 90 and 120 days afterVC the sound intensities of F2and F3returned to baseline values. The Puiand SL, were significantly decreased compared to LH values, but remained different from baseline.

Conclusions: VC effectively reduces inspiratory noise in LH‐affected horses by 90 days following surgery. Inspiratory trans‐upperairway pressures are improved 30 days following VC, but do not return to baseline values.

Potential relevance: VC can be recommended as a surgical treatment of LH‐affected horses if reduction of respiratory noise is the primary objective of surgery. Further studies are required to determine if variations of the surgical technique used in this study will have similar results.
Lateral transmission of equine arteritis virus among Lipizzaner stallions in South Africa
Authors: GUTHRIE A. J. , HOWELL P. G. , HEDGES J. F. , BOSMAN A.‐M. , BALASURIYA U. B. R. , McCOLLUM W. H. , TIMONEY P. J. , MacLACHLAN N. J.
Published: April 2007

Reasons for performing study:A serological study conducted in 1995 revealed that 7 stallions at the Lipizzaner Centre, Gauteng, South Africa, were seropositive for antibody to equine arteritis virus (EAV). A Lipizzaner stallion imported into South Africa from Yugoslavia in 1981 had previously (1988) been confirmed to be an EAV carrier. Despite being placed under life‐long breeding quarantine, EAV had been transmitted between stallions at the Lipizzaner Centre.

Objectives: To investigate the phylogenetic relationships between the strain of EAV shed in the semen of the original carrier stallion and strains recovered from the semen of 5 other stallions; and to investigate the means whereby lateral transmission of EAV occurred among 7 in‐contact, nonbreeding stallions at the Centre.

Methods: EAV was isolated from semen collected from the seropositive stallions using RK‐13 cells. Viral RNA was reverse transcribed and amplified by polymerase chain reaction using ORF5‐specific primers, subjected to sequence and phylogenetic analysis.

Results: Phylogenetic analysis of strains of EAV recovered from the semen of 6 persistently infected stal lions confirmed that all viruses were closely related and probably derived from a common ancestor, i.e. the stallion imported from Yugoslavia. Lateral transmission subsequently occurred among 7 in‐contact, nonbreeding stallions at the Centre. It is speculated that these stallions may have been exposed to virus from be dding or fo mites contaminated with semen.

Conclusions: These data confirm that lateral transmission of EAV can occur from shedding stallions to susceptible, in‐contact horses, including other stallions, which may become persistently infected with the virus.

Potential relevance: The findings are consistent with lateral spread of a single, unique strain of EAV among a group; and suggest that transmission of EAV may be initiated by infection of one or more stallions with virus on bedding or other fomites contaminated with EAV‐infected semen.
Equine hepatic disease: the effect of patient‐ and case‐specific variables on risk and prognosis
Authors: SMITH M. R. W. , STEVENS K. B. , DURHAM A. E. , MARR C. M.
Published: April 2007

Reasons for performing study: Liver disease is fairly common in horses and, although previous literature suggests that fatality rates are high, impressions gained from current clinical practice suggest that this is no longer the case.

Objectives: A case‐control study was undertaken in 2 hospitals to investigate whetherage, gender or breed type predisposed horses to developing hepatic disease, with the additional aim of determining whether these factors and disease category had any effect on outcome.

Methods: Eighty‐eight cases were identified by review of computerised archives at 2 hospitals. Three cases admitted immediately before and afterthe cases were used as controls. Multivariant models were developed to explore the relationship between age, breed type and gender and the development of liverdisease, and within the clinical cases, to identify whetherany of these factors orspecific forms of liver disease were associated with fatality rate.

Results: Ponies were more likely to develop hepatic disease than light riding horses, but neither age nor gender were significant risk factors. Overall, the fatality rate was fairly low; horses with unclassified hepatopathies had the lowest fatality rate and those with cholangiohepatitis, pyrrolizidine alkaloid toxicity and chronic active hepatitis had significantly higher fatality rates in comparison. However, age, breed type and gender had no detectable effect on outcome.

Conclusions and potential relevance: Such data could be of particular value to equine practitioners, as the cases were drawn from both primary and referral practice, and were all seen within the last 5 years.
Severe hypertriglyceridaemia in clinically ill horses: diagnosis, treatment and outcome
Authors: DUNKEL B. , III H. C. McKENZIE
Published: April 2007

Reasons for performing study: Sporadic measurement of serum triglycerides in depressed and inappetant clinically ill horses revealed severe hypertriglyceridaemia without visible evidence of lipaemia on several occasions, leading to the inclusion of serum triglyceride concentrations in the routine serum biochemistry evaluation of our hospital. Since then, more cases have been identified and treated for hypertriglyceridaemia, raising questions about the prevalence, predisposing factors and significance of these findings.

Hypotheses: 1) Severe hypertriglyceridaemia without visible opacity of the serum occurs more commonly in clinically ill and inappetant horses than previously described and 2) appropriate treatment using i.v. dextrose and/or partial parenteral nutrition would decrease serum triglycerides to normal limits and might result in improved appetite and attitude of the patient.

Methods: The laboratory computer database from 2000 and 2001 was searched for increased serum triglycerides (>5.65 mmol/l) in any horse breed, ponies and miniature breeds excluded. Data analysed included subject details, diagnosis, clinical and laboratory parameters, treatment, response to treatment and outcome.

Results: Severe hypertriglyceridaemia was identified in 13 horses, with serum triglyceride concentrations 6.17–18.29 mmol/l, while none showed visible lipaemia. All horses had clinical and laboratory findings consistent with systemic inflammatory response syndrome and all but one had an increased serum creatinine concentration. Treatment with i.v. dextrose and/or partial parenteral nutrition resulted in decrease of the serum triglycerides to normal limits.

Conclusions: Severe hypertriglyceridaemia occurs in inappetant and clinically ill horses without evidence of serum opacity more commonly than previously described. The presence of systemic inflammatory response syndrome might predispose horses to hypertriglyceridaemia, while the increased creatinine concentration might be a predisposing factor or result of the condition. Horses identified in our study readily responded to treatment and appetite and attitude improved coincident with decrease of the serum triglycerides to normal limits.

Potential relevance: Hypertriglyceridaemia could perpetuate inappetance and depression in clinically ill horses and potentially predispose to fatty infiltration of the liver and other organ systems.
Retrospective analysis of historical, clinical, ultrasonographic, serum biochemical and haematological data in prognostic evaluation of equine liver disease
Authors: DURHAM A. E. , NEWTON J. R. , SMITH K. C. , HILLYER M. H. , HILLYER L. L. , SMITH M. R. W. , MARR C. M.
Published: April 2007

Reasons for performing study: Results of noninvasive tests of liver disease do not always correlate with the degree of hepatic disease nor outcome of the case.

Objective: To investigate the prognostic value of data collected using noninvasive tests during the investigation of cases of suspected liver disease in mature horses.

Hypothesis: Much of the data gathered during the investigation of suspected hepatopathy cases offers little prognostic guidance and interpretation of such data can be misleading.

Methods: The results from a range of common and noninvasive diagnostic techniques applied in 116 mature horses with suspected liver disease, were assessed for their ability to predict survival within a 6 month period.

Results: A significantly poorer prognosis was found in association with clinical signs suggestive of liver disease, presence of hepatic encephalopathy, ultrasonographic abnormalities, increased serum globulins, increased total bile acids (TBA), increased alkaline phosphatase (AP), increased gamma‐glutamyl transferase (γGT), erythrocytosis, leucocytosis, low serum albumin and low serum urea. Additional significant novel findings of interest included an association between increased plasma fibrinogen and low serum creatinine concentrations with nonsurvival in cases of liver disease, an association between raised serum concentrations of AP and γGT with biliary hyperplasia and also an association between hepatic fibrosis, haemosiderosis and biliary hyperplasia with ultrasonographically detected hepatic abnormalities.

Conclusions: The most useful noninvasive prognostic test in cases of suspected liver disease in mature horses is the severity of clinical signs. Other data may be of some limited prognostic value.

Potential relevance: Application of the findings in this study may not be directly applicable to other case populations. However, the findings should at least be considered when prognosis is based on similar criteria.
Occurrence of infectious upper respiratory tract disease and response to vaccination in horses on six sentinel premises in northern Colorado
Authors: MUMFORD E. L. , TRAUB‐DARGATZ J. L. , CARMAN J. , CALLAN R. J. , COLLINS J. K. , GOLTZ K. L. , ROMM S. R. , TARR S. F. , SALMAN M. D.
Published: April 2007

Reasons for performing study: Horses vaccinated against common agents of infectious upper respiratory disease (IURD) may not have detectable serum antibody and may not be protected from clinical disease.

Objectives: The objectives of this study were to 1) investigate the serological response of horses to vaccination against influenza virus (H3N8 and H7N7) and equine herpesviruses (EHV) in a field setting and 2) evaluate associations among vaccination status, serum antibody concentrations, and occurrences of IURD in monitored horses.

Methods: In this study, horses on 6 Colorado premises were vaccinated parenterally against influenza virus and EHV, and serological response evaluated. Horses were monitored, and biological samples collected from individuals with clinical IURD and control horses.

Results: Of 173 horses, 61 (35.3%), 21 (12.1%) and 4 (2.3%) seroconverted in response to vaccination against EHV, influenza virus H7N7 and influenza virus H3N8, respectively.

Conclusions: Outbreaks of IURD in study horses were associated with influenza virus H3N8 andStreptococcus equiinfection, and serological response to vaccination with conventional products was poor.

Potential relevance: These results confirm that horses may not respond with detectable serological responses to conventional vaccination against common respiratory viruses and, therefore, suggest that alternate methods of protecting horses against common respiratory viruses should be sought.
Influence of liver copper status of mare and newborn foal on the development of osteochondrotic lesions
Authors: WEEREN P. R. van , KNAAP J. , FIRTH E. C.
Published: April 2007

Reason for performing study: To elucidate the highly contentious role of copper in the pathogenesis of osteochondrosis.

Hypothesis: There would be no relationship between liver copper concentration of mares and foals and incidence of radiographically detectable osteochondrotic lesions in foals and yearlings was tested.

Methods: Liver copper concentration was assessed in biopsies taken within 4 days after birth from both mares and foals and from the same foals at age 5 months. Biopsies were taken in the standing, sedated animal under ultrasonographic guidance. Radiographs were taken of both hocks (lateromedial, dorsoplantar and dorsomedial‐plantarolateral oblique views) and stifles (lateromedial and caudolateral‐craniomedial oblique views) at ages 5 and 11 months and scored for the presence and severity of osteochondrotic lesions.

Results: Copper concentrations in newborn foals were high with a large variation (351 ± 201 mg/kg DM). They declined until reaching values comparable to those in mature animals at 5 months (20 ± 8 mg/kg DM; mares: 19 ± 20 mg/kg DM). Radiographic osteochondrotic lesions decreased in number and severity from 5 to 11 months. This pattern was more predominant in the stifle than in the hock, as has been described previously.

Conclusions: There was no relationship between foal or mare liver copper concentration and osteochondrosis status at either 5 or 11 months. However, osteochondrotic lesions in foals with low‐level copper status at birth decreased significantly less in number and severity than those in foals with high‐level copper status at birth.

Potential relevance: It is concluded that copper is not likely to be an important factor in the aetiopathogenesis of osteochondrosis, but this study indicates that there may be a significant effect of high copper status on the natural process of repair of early lesions.
Magnetic resonance imaging of the equine foot: 15 horses
Authors: DYSON S. , MURRAY R. , SCHRAMME M. , BRANCH M.
Published: April 2007

Reasons for performing study: Foot pain is a common cause of equine lameness and there have been significant limitations of the methods available for the diagnosis of the causes of foot pain (radiography, nuclear scintigraphy and ultrasonography). Until recently, magnetic resonance imaging (MRI) in the horse has been limited to examination of cadaver limbs.

Objectives: Our purpose was to 1) describe MRI of the foot in live horses, 2) describe MRI findings in horses with foot pain in which a definitive diagnosis could not be established by alternative means and 3) correlate MRI findings with other methods of clinical investigation.

Methods: The feet of 15 horses with unilateral (12) orbilateral (3), forelimb (14) or hindlimb (1) lameness associated with foot pain of previously ill‐defined origin were examined using MRI. The horses were examined in right lateral recumbency under general anaesthesia, with the feet positioned in the isocentre of a flared end 1.5 Tesla GE Signa Echospeed magnet. Images were obtained in sagittal, transverse and dorsal planes using 3‐dimensional (3D) T2* gradient echo (GRE), spoiled gradient echo, fat‐saturated 3D T2* GRE and short inversion recovery sequences. Image acquisition took approximately 1 h.

Results: Abnormalities of the distal interphalangeal joint (DIP) cartilage and /or subchondral bone, periarticular osteophyte formation, distension of the DIP joint capsule with or without synovial proliferation, distension of the navicular bursa with or without evidence of chronic inflammation, surface and core lesions in the deep digital flexor tendon, abnormal signal within the navicular bone, evidence of mineralised fragments in the distal sesamoidean impar ligament, irregular outline of and signal in the medial cortex of the distal phalanx, and an abnormal signal on the dorsal aspect of the distal phalanx consistent with laminitis were identified.

Conclusions: MRI permits the diagnosis of a variety of lesions involving different structures within the foot that cannot be diagnosed using other means, thus enhancing our knowledge of the causes of foot pain.

Potential relevance: With further experience it is likely that lesions involving other structures will also be identified. Long‐term follow‐up data is required to determine the prognosis for the injuries described.
Detection of EHV‐1 and EHV‐4 in placental sections of naturally occurring EHV‐1‐ and EHV‐4‐related abortions in the UK: use of the placenta in diagnosis
Authors: GERST S. , BORCHERS K. , GOWER S. M. , SMITH K. C.
Published: April 2007

Reasons for performing study: EHV‐1 and EHV‐4 abortion diagnosis is based upon detailed examination of the aborted fetus. However, in some cases, only the placenta is available for examination. Furthermore, the contribution of lesions in the placenta to pathogenesis and diagnosis of EHV‐1 and EHV‐4 abortion has been neglected.

Objectives: To assess the utility of placental examination in equine herpesvirus‐1 (EHV‐1) and EHV‐4 abortion diagnosis.

Methods: Sections of allantochorion from 49 herpesvirus abortions were analysed by PCR,in situhybridisation and immunostaining.

Results: Virus‐specific nested PCR confirmed the presence of viral DNA in 46 cases; 41 cases were EHV‐1‐positive and 5 EHV‐4‐positive. Microscopic changes were nonspecific. Examination of the PCR‐positive sections of allantochorion revealed EHV‐1 DNA byin situhybridisation (ISH) in 21 cases and EHV‐4 in 4 cases. In 2 samples, DNA of both viruses was present on PCR and ISH. Viral antigen was found by immunohistology in 15 cases. Regarding the localisation of virus in the placentae, both viral DNA and antigen of EHV‐1 and EHV‐4 were found in endothelial cells of chorionic villi and, occasionally, in trophoblast epithelium. In the stromal endothelium, only EHV‐1 was found.

Conclusions: The data indicate that examination of placentae is a useful diagnostic aid in EHV‐1 and EHV‐4 abortion diagnosis.

Potential relevance: Virological examination of the placenta should be come standard practice in equine abortion investigations, particularly in those cases where the fetus is not available for examination.
Effects of lipopolysaccharide and phenylbutazone on gastric contents in the horse
Authors: DOHERTY T. J. , ANDREWS F. M. , BLACKFORD J. T. , ROHRBACH B. W. , SANDIN A. , SAXTON A. M.
Published: April 2007

Reasons for performing study: Endotoxaemia causes a disruption of gastrointestinal motility in the horse but there is no information on its effects on gastric secretion. Lipopolysaccharide (LPS) administration is known to affect gastric secretion in other species.

Hypothesis: That LPS, a toxic component of Gram‐negative bacteria, would reduce gastric acid secretion and that pretreatment with phenylbutazone (PBZ) would block the effects of LPS.

Methods: The effects of LPS and PBZ on gastric contents were investigated in fasted, mature horses, with permanent gastric cannulae. Horses were pretreated with either saline or PBZ 15 mins before a 60 min infusion of either LPS or saline. Gastric contents were collected at 15 min intervals for 3 h, beginning 15 mins after the start of the LPS or saline infusion.

Results: Lipopolysaccharide significantly decreased gastric acid output, [K+] and potassium output and increased [Na+] and sodium output. Phenylbutazone did not affect basal gastric acid secretion but decreased LPS‐induced changes in the secreted volume, [Na+] and sodium output.

Conclusions: This study provides evidence that LPS affects gastric acid secretion in the horse and that these LPS‐induced changes are mediated, in part, by prostaglandins.

Potential relevance: Lipopolysaccharide administration can induce changes in the composition of gastric contents in the horse but further work is needed to determine the source of these changes.
Dynamic compressive strain inhibits nitric oxide synthesis by equine chondrocytes isolated from different areas of the cartilage surface
Authors: WISEMAN M. , HENSON F. , LEE D. A. , BADER D. L.
Published: April 2007

Reasons for performing study: Chondrocytes within articular cartilage respond to the mechanical stresses associated with normal joint loading via a series of signalling pathways. Specific biomolecules, such as nitric oxide (NO), have been implicated in these mechanotransduction processes. It has been shown that the synthesis of NO can be inhibited by dynamic compressive strain of chondrocytes in vitro which, in turn, leads to an up‐regulation of specific metabolic parameters.

Hypothesis: Chondrocytes isolated from different joint locations and seeded in agarose constructs respond in a distinct manner to the application of dynamic compression.

Methods: Chondrocytes were isolated separately from the equine patella groove and the femoral condyle, representing high loaded areas (HLA) and low loaded areas (LLA), respectively, of 6 specimens of different ages. The cells were seeded in agarose constructs and cultured either in an unstrained state or strained under dynamic loading at 1 Hz for 48 h. The synthesis of nitric oxide (NO), proteoglycan synthesis and chondrocyte proliferation were assessed.

Results: Equine chondrocytes were found to synthesise significant basal levels of NO, regardless of topographical origin or age of tissue. Marked differences in both proteoglycan synthesis and cell proliferation were, however, revealed between the 2 chondrocyte subpopulations. Dynamic compression inhibited NO synthesis but significant alterations in proteoglycan synthesis and cell proliferation were apparent in a minority of cases.

Conclusions and potential relevance: The differential response of the subpopulations of chondrocytes derived from the HLA and LLA provides a potential mechanism which enables the biomechanical demands of differing joint regions to be maintained.
Ultrasonography of the equine cervical region: a descriptive study in eight horses
Authors: Berg L. C. , Nielsen J. V. , Thoefner M. B. , Thomsen P. D.
Published: April 2007

Reasons for performing study: In equine patients, the cause of clinical signs possibly related to the cervical region is often difficult to diagnose. Ultrasonography allows quick and noninvasive visualisation, but reference material of the normal equine neck is needed.

Objectives: To describe and document the normal ultrasonographic appearance of transverse scans in the cervical region with emphasis on the synovial articular facet joints, cervical vertebrae and paravertebral structures; and further, to provide images of frozen cross‐sections for anatomical reference.

Methods: A study describing the normal ultrasonographic appearance of the cervical anatomy was performed. Transverse scans were obtained from second cervical vertebra (C2) to first thoracic vertebra (T1). Post mortem photographs of frozen cross‐sections were obtained as anatomical reference.

Results: The structures were clearly visualised by ultrasonography and consistency was found between ultrasonographic images and corresponding cross‐sectional anatomy. The articular facets varied between horses and facets (C2 to T1). Discrepancy in the existing anatomical descriptions was found.

Conclusions and potential relevance: The anatomical and ultrasonographic description provides a reference for ultrasonographic evaluation of equine cervical facet joints, vertebrae and paravertebral structures. The findings and variations found are considered to reflect the naturally occurring variations in horses.
Evaluation of in vitro properties of di‐tri‐octahedral smectite on clostridial toxins and growth
Authors: Weese J. S. , Cote N. M. , Degannes R. V. G.
Published: April 2007

Reasons for performing study: Clostridial colitis and endotoxaemia of intestinal origin are significant causes of morbidity and mortality in horses. Intestinal adsorbents are available for treatment of these conditions; however, little information exists supporting their use.

Objectives: To evaluate the ability of di‐tri‐octahedral smectite to bind toClostridium difficiletoxins A and B,C. perfringensenterotoxin and endotoxin, inhibit clostridial growth and the actions of metronidazolein vitro.

Methods: Clostridium difficiletoxins,C. perfringensenterotoxin and endotoxin were mixed with serial dilutions of di‐tri‐octahedral smectite, then tested for the presence of clostridial toxins or endotoxin using commercial tests. Serial dilutions of smectite were tested for the ability to inhibit growth ofC. perfringensin culture broth, and to interfere with the effect of metronidazole on growth ofC. perfringensin culture broth.

Results: Clostridium difficiletoxins A and B, andC. perfringensenterotoxin were completely bound at dilutions of 1:2 to 1:16. Partial binding ofC. difficiletoxins occurred at dilutions up to 1:256 while partial binding ofC. perfringensenterotoxin occurred up to a dilution of 1:128. Greater than 99% binding of endotoxin occurred with dilutions 1:2 to 1:32. No inhibition of growth ofC. difficileorC. perfringenswas present at any dilution, and there was no effect on the action of metronidazole.

Conclusions: Di‐tri‐octahedral smectite possesses the ability to bindC. difficiletoxins A and B,C. perfringensenterotoxin and endotoxinin vivowhile having no effect on bacterial growth or the action of metronidazole.

Potential relevance: In vivostudies are required to determine whether di‐tri‐octahedral smectite might be a useful adjunctive treatment of clostridial colifis and endotoxaemia in horses.
Meniscal tears in horses: an evaluation of clinical signs and arthroscopic treatment of 80 cases
Authors: WALMSLEY J. P. , PHILLIPS T. J. , TOWNSEND H. G. G.
Published: April 2007

Reasons for performing study: There is little published information available describing clinical signs, arthroscopic findings and prognosis of meniscal injuries in horses.

Objectives: To evaluate the effect on the outcome not only of the arthroscopic findings and treatment, but also of the clinical and radiographic signs in these horses.

Methods: The following were recorded for each case: the meniscal injury, graded according to severity; clinical and radiographic findings prior to surgery; any concurrent injury in the joint seen at arthroscopy. The effect of these factors and the grade of injury on the outcome were analysed using Fisher's exact test or Chi‐square analysis. Only horses whose meniscal injury was judged to be the primary cause of lameness were included in the series.

Results: A series of 80 meniscal injuries were diagnosed and treated arthroscopically by the authors at the Liphook Equine Hospital and 47% of horses returned to full use. Statistically, poor prognosis was associated with increasing severity of the meniscal injury, the presence of concurrent articular cartilage lesions and radiographic abnormalities in the joint. Arthroscopic treatment of many lesions was limited by the inaccessibility of parts of the femorotibial joint.

Potential relevance: Further work is required to improve and evaluate arthroscopic techniques for the treatment of these injuries.
Radiographic changes in Thoroughbred yearlings. Part 1: Prevalence at the time of the yearling sales
Authors: KANE A. J. , PARK R. D. , McILWRAITH C. W. , RANTANEN N. W. , MOREHEAD J. P. , BRAMLAGE L. R.
Published: April 2007

Reasons for performing study: Radiography in presale examinations of TB yearlings has become standard practice in recent years.

Objectives: To describe the prevalence and distribution of radiographic changes in the fetlocks, carpi, tarsi, stifles and fore feet of Thoroughbred yearlings in central Kentucky when these joints were examined as part of routine pre‐ and post sale evaluations.

Methods: Horses subjected to radiographs included the fore (n = 1127) and hind (n = 1102) fetlocks, carpi (n = 1130), tarsi (n = 1101), stifles (n = 660) and fore feet (n = 300). Radiographic changes were categorised by location and type of change present (e.g. lucency, fragment) for each series.

Results: In the fore fetlocks 1.6% had fragmentation of the proximal dorsal first phalanx and 0.5% fragmentation of the proximal palmar aspect. In the hind fetlocks 5.9% had fragmentation at the plantar aspect and 3.3% fragmentation dorsally. Lucencies, fragments or loose bodies were detected at the dorsal aspect of the distal third metacarpus in 2.8% and, at the same location on the third metatarsus, 3.2%. Most yearlings (98%) had vascular channels in the proximal sesamoid bones and irregularvascular channels (>2 mm wide or with nonparallel sides) were more common (79%) than regular vascular channels (56%). The intermediate ridge of the distal tibia was the most common location for fragmentation in the tarsus (4.4%).

Conclusions: While some radiographic changes, e.g. vascular channels in proximal sesamoid bones, are very common in Thoroughbred yearlings, others, e.g. fragmentation or subchondral lucency within joints are quite rare usually affecting less than 5% of the population.

Potential relevance: Veterinarians should expect to find radiographic changes in Thoroughbreds presented for examination prior to the yearling sales. The rarity of some changes thought to affect soundness or racing performance will make further invesigation of these conditions in horses without clinical signs more difficult.
Prolonged suppression of the innate immune system in the horse following an 80 km endurance race
Authors: ROBSON P. J. , ALSTON T. D. , MYBURGH K. H.
Published: April 2007

Reasons for performing study: An increased susceptibility to bacterial and viral infections of the respiratory tract, which results in a loss of performance, has been reported in racehorses. Much research has focused on the influence of high‐intensity exercise of a short duration on immune system function in horses, but scant attention has been given to prolonged endurance exercise as an immune modulator.

Objectives: The objective of this study was to evaluate the effect of an 80 km endurance race on the monocyte and neutrophil oxidative burst, serum Cortisol, glutamine and plasma glucose concentrations in 8 endurance‐trained horses (mean ± s.d. age 9.4 ± 2.2 years).

Methods: Blood samples were drawn from the horses prior to and following an 80 km ride.

Results: Mean time for completion of the 80 km race was 306 ± 40 mins. Immediately post race mean serum Cortisol concentration, blood monocyte and neutrophil counts were higher and blood lymphocyte counts and plasma glucose concentration were lower compared with prerace values (P<0.05). Neutrophil and monocyte oxidative burst activity decreased following the race and had not regained prerace values after 3 days of rest (P<0.05).

Conclusions: The present study indicates that long duration exercise in horses has a negative impact on the function of the innate immune system that lasts several days post race. Precise mechanisms instigating the fall in innate immune system function are unclear and multifactorial, but may be attributed, at least in part, to a high serum Cortisol response during very prolonged exercise.

Potential clinical relevance: A prolonged bout of exercise results in a long‐term suppression of the innate immune system function in horses which may, in part, account for the observed increase of infectious episodes in horses during training.
Conservative management of 17 horses with nonarticular fractures of the tibial tuberosity
Authors: ARNOLD C. E. , SCHAER T. P. , BAIRD D. L. , MARTIN B. B.
Published: April 2007

Reasons for performing study: Fractures of the tibial tuberosity (FTT) are caused by direct trauma, and are the second most commonly reported injury in event horses with stifle trauma. Conservative management of horses with FTT has been advocated, but results and prognosis for this method of therapy are unknown.

Objectives: To report and review the findings of a retrospective study of 17 horses admitted to a veterinary teaching hospital from 1986–2001 with nonarticular FTT that received conservative management.

Methods: Subject details, aetiology of the accident, limb affected, degree of lameness at time of admission, size and degree of displacement of the fracture fragment, complications such as comminution of the fracture fragment or damage to soft tissue structures within the affected stifle, and treatment recommendations were obtained from medical records. Owners and trainers were contacted regarding the horse's return to athletic use. The follow‐up period consisted of 11–154 months.

Results: Two horses were reportedly sound, but unable to return to competition for unrelated reasons. Of the horses that completed the rehabilitation period, 12/15 (80%) returned to athletic use at the same level as before the injury. Three horses were diagnosed with damage to soft tissue supporting structures of the affected stifle and could not return to their former level of competition.

Conclusions: Concurrent soft tissue damage, diagnosed at the time of the initial injury, was statistically significant in precluding horses from returning to athletic careers. All other variables were found to have no effect upon outcome.

Potential clinical relevance: This retrospective study suggests that the conservative management of nonarticular FTT is a viable treatment modality in managing athletic equine patients presenting with these fractures.
Recombinant equine growth hormone administration: effects on synovial fluid biomarkers and cartilage metabolism in horses
Authors: DART A. J. , LITTLE C. B. , HUGHES C. E. , CHU Q. , DOWLING B. A. , HODGSON D. R. , ROSE R. J. , JOHNSON K. A.
Published: April 2007

Reasons for performing study: Recombinant equine growth hormone (reGH) has recently been evaluated for effects on body condition and wound healing. It has the potential to influence articular cartilage via stimulation of IGF‐1.

Objectives: To investigate effects of administration on synovial joint metabolism.

Methods: Six mature horses were given 20 μg/kg bwt reGH daily for 8 weeks by i.m. injection. Three control horses were injected with sterile water. Serum and synovial fluid samples were collected at 6, 8, 11 and 16 weeks for GH and IGF‐1 assays. Articular cartilage harvested at week 16 was evaluated by Western analysis using monoclonal antibodies BC‐13, BC‐4, 8‐A‐4 and CH‐3.

Results: Concentrations of IGF‐1 in serum and synovial fluid were significantly elevated (P < 0.05) at 6 and 8 weeks in the reGH group. Glycosaminoglycan concentrations in synovial fluid were significantly less than controls at these time points, suggesting that reGH may modulate proteoglycan metabolism in articular cartilage. In the reGH group, there were not any alterations in synovial fluid content of 3B3(‐) epitope or aggrecan metabolite, or in aggrecan or link protein catabolites retained within cartilage, that might be expected with development of osteoarthritis.

Conclusions: Intramuscular administration of reGH may be a more efficient means of delivery of IGF‐1 to joints for cartilage resurfacing initiatives.

Potential relevance: We found no alterations in cartilage metabolism indicative of development of osteoarthritis.
Effects of propylthiouracil and bromocryptine on serum concentrations of thyrotrophin and thyroid hormones in normal female horses
Authors: JOHNSON P. J. , IV N. T. MESSER , GANJAM V. K. , THOMPSON D. L. , REFSAL K. R. , LOCH W. E. , ELLERSIECK M. R.
Published: April 2007

Reasons for performing study: There exists a need for better diagnostic tests to characterise thyroid disease in horses. Currently available diagnostic tests fail to diff erentiate between thyroid gland disorders and thyroid abnormalities resulting from pituitary or hypothalamic problems.

Objectives: To evaluate the effects of treatment with propylthiouracil (PTU) and bromocryp tine (BROM) on serum concentrations of triiodothyronine (T3), thyroxine (T4), reverse T3 (rT3) and equine thyroid‐stimulating hormone (e‐TSH, thyrotrophin) in mature horses.

Methods: Healthy mature horses were treated using either PTU or BROM for 28 days. The effect of treatment on the thyroid axis was assessed by measuring T3, T4, rT3 and e‐TSH before and at +14 and +28 days. The effect of PTU and BROM on the response of T3, T4, rT3 and e‐TSH to thyrotrophin‐release hormone (TRH) administration was also assessed before and at +14 and +28 days of treatment.

Results: Treatment with PTU led to a significant reduction in serum concentrations of T3, T4 and rT3 on Day 28 and increase of e‐TSH on Day 28 (P < 0.05). Treatment with BROM did not cause any measurable effect on serum concentrations of T3, T4, rT3 or e‐TSH. The percentage increment by which serum concentration of T4, T3 and e‐TSH increased following stimulation with TRH was decreased by treatment with PTU for 28 days (P < 0.05) but were not affected by treatment with BROM for 28 days.

Conclusions: These results suggest that 1) treatment with PTU may be used in horses as a model of primary hypothyroidism; 2) the use of BROM as a model of secondary hypothyroidism in horses is not supported; and 3) e‐TSH assay deserves further investigation for the clinical diagnosis of thyroid axis dysfunction in horses.

Potential relevance: Propylthiouracil effectively causes primary hypothyroidism. There is substantial variability between horses with respect to their sensitivity to this substance when administered orally. Further studies pertaining to the characterisation of equine thyroid disorders are warranted and the use of both PTU for the experimental induction of primary hypothyroidism and e‐TSH for the diagnostic characterisation of thyroid disorders in horses should be considered.
Energetic and kinematic consequences of weighting the distal limb
Authors: WICKLER S. J. , HOYT D. F. , CLAYTON H. M. , MULLINEAUX D. R. , COGGER E. A. , SANDOVAL E. , MCGUIRE R. , LOPEZ C.
Published: April 2007

Reason for performing study: It is well known that adding a load to a horse's back increases its energetic costs of locomotion, but the magnitude of increase obtained by loading the most distal portion of limb has not been measured.

Objectives: To measure oxygen consumption in horses with mass added to the back and hooves. Because such mass distribution alters inertial parameters of the limbs, kinematic measurements were made to quantify the magnitude of change in limb movement.

Methods: Steady‐state oxygen consumption was measured in 6 horses with a load of 2.4 kg. The load was either carried on the back or distributed equally between the 4 limbs. Modified bell boots kept the mass at the level of P3. Horses trotted on a treadmill at speeds ranging from 2 to 5 m/sec (in 0.5 m/sec increments). High‐speed (250 Hz) digital images were recorded in a sagittal plane and the positions of retroreflective markers located on standard positions on the limbs were digitised for kinematic analysis.

Results: Loading of the distal limbs produced a 6.7% increase in metabolic rate, an order of magnitude higher than when the mass was added over the back. Although the stride period was 2% longer in horses with loads on the distal limbs, time of contact and duty factor were not different. Distal limb loading increased the range of motion in hind‐but not forelimbs.

Conclusions: The costs of swinging the limbs in the horse are considerable and the addition of weights to the distal limb can have a profound effect on not only the energetics of locomotion but also the kinematics, at least in the hindlimb.

Potential relevance: The use of weighted shoes, intended to increase animation of the gait, increases the metabolic effort of performance horses a disproportionate amount. The additional mass also increases the joint range of motion and, potentially, the likelihood of injury.
Determination of the stiffness of the equine spine
Authors: SCHLACHER C. , PEHAM C. , LICKA T. , SCHOBESBERGER H.
Published: April 2007

Reasons for performing study: Mechanical properties of the equine back are the bases for realistic modelling of the back, which is recognised as an important step towards improved understanding of the pathogenesis of equine back conditions.

Hypothesis: The stiffness of the equine back depends on the direction of the applied force and on the position of the spine.

Methods: Fourteen dissected spines were tested in a tensile testing machine. In 3 different positions, simulating dorsoventral, laterolateral and dorsoventral‐30° rotated movement, force was applied on the dorsal spinous process of T12 to reach an excursion of 4 cm in each direction. The normal distribution of the stiffness coefficients was tested with a Kolmogorov‐Smirnov test and the stiffness coefficients were compared with paired t tests.

Results: Mean ± s.d. dorsoventral stiffness was 2093 ± 611 N/m for the nonrotated spine and 2182 ± 459 N/m for the 30° rotated spine. Mean laterolateral stiffness was significantly lower than dorsoventral stiffness at 1454 ± 156 N/m.

Conclusions: The stiffness of the spine depends on the direction of loading.

Potential relevance: The stiffness of the spine under loading may be a relevant factor in the development of back disorders.
Development of a 3D model of the equine distal forelimb and of a GRF shoe for noninvasive determination of in vivo tendon and ligament loads and strains
Authors: ROLLOT Y. , LECUYER E. , CHATEAU H. , CREVIER‐DENOIX N.
Published: April 2007

Reasons for performing study: As critical locomotion events (e.g. high‐speed and impacts during racing, jump landing) may contribute to tendinopathies, in vivo recording of gaits kinematic and dynamic parameters is essential for 3D reconstruction and analysis.

Objective: To propose a 3D model of the forelimb and a ground reaction force recording shoe (GRF‐S) for noninvasively quantifying tendon and ligament loads and strains.

Methods: Bony segments trajectories of forelimbs placed under a power press were recorded using triads of ultrasonic kinematic markers linked to the bones. Compression cycles (from 500–6000 N) were applied for different hoof orientations. Locations of tendon and ligament insertions were recorded with regard to the triads. The GRF‐S recorded GRF over the hoof wall and used four 3‐axis force sensors sandwiched between a support shoe and the shoe to be tested.

Results: Validation of the model by comparing calculated and measured superficial digital flexor tendon strains, and evaluation of the role of proximal interphalangeal joint in straight sesamoidean ligament and oblique sesamoidean ligament strains, were successfully achieved. Objective comparisons of the 3 components of GRF over the hoof for soft and hard grounds could be recorded, where the s.d. of GRF norm was more important on hard ground at walk and trot.

Conclusions: Soft grounds (sand and rubber) dissipate energy by lowering GRF amplitude and diminish bounces and vibrations at impact. At comparable speed, stance phase was longer on soft sand ground.

Potential relevance: The conjugate use of the GRF‐S and the numerical model would help to quantify and analyse ground/shoe combination on comfort, propulsion efficiency or lameness recovery.
Effects of 6° elevation of the heels on 3D kinematics of the distal portion of the forelimb in the walking horse
Authors: CHATEAU H. , DEGUEURCE C. , DENOIX J.‐M.
Published: April 2007

Reasons for performing study: Understanding of the biomechanical effects of heel elevation remains incomplete becausein vivostudies performed with skin markers do not measure the actual movements of the 3 digital joints.

Objective: To quantify the effects of 6° heel wedge on the 3‐dimensional movements of the 4 distal segments of the forelimb in the walking horse.

Methods: Four healthy horses were used. Kinematics of the distal segments was measured invasively with a system based on ultrasonic triangulation. Three‐dimensional rotations of the digital joints were calculated by use of a ‘joint coordinate system’ (JCS). Data obtained with heel wedges were compared to those obtained with standard shoes during the stance phase of the stride.

Results: Heel wedges significantly increased maximal flexion of the proximal (PIPJ) and distal (DIPJ) interphalangeal joints and maximal extension (mean ± s.d. +0.8 ± 0.3°) of the metacarpophalangeal joint (MPJ). Extension of the PIPJ and DIPJ was decreased at heel‐off. Few effects were observed in extrasagittal planes of movement.

Conclusions: Heel wedges affect the sagittal plane kinematics of the 3 digital joints.

Potential relevance: Controversial effects previously observed on the MPJ may be explained by the substantial involvement of the PIPJ, which was wrongly neglected in previous studies performed on the moving horse.