Animal Health Trust Research Articles

What Effect Does Medium and Extended Trot Have on the Kinematics of the Forelimb in Dressage Horses?

Reasons for performing studyMetacarpophalangeal joint hyperextension overload is increasingly being recognised in dressage horses and, like forelimb suspensory ligament injury, tends to be seen in horses with extravagant trot steps. However, there is limited understanding of the effects of different paces within the trot on forelimb movement, therefore it is difficult to advise rationally on prevention or management of these types of injury.ObjectivesTo compare forelimb kinematics of collected and medium or extended trot in dressage horses.Study designProspective study.MethodsTwenty mixed‐breed dressage horses (age 9 ± 4 years; height 168 ± 6 cm; weight 600 ± 63 kg; median competition level = advanced medium) were tested at collected and medium/extended trot (age and training level dependent) in a straight line on an artificial surface ridden by their own rider at sitting trot. Four strides of each pace were recorded using high speed motion capture (240 Hz). Markers were placed on the horses' forelimbs at predetermined anatomical sites. Fetlock, carpus, elbow and shoulder angles were derived at midstance. Descriptive statistics and mixed effect multilevel regression analyses were performed on the data.ResultsFetlock extension angle was significantly increased at medium compared with collected trot (coefficient: 5.70; CI 2.58–8.82; P<0.01) and extended compared with collected trot (coefficient: 8.59; CI 5.16–12.02; P<0.01). Fetlock extension angle was significantly increased when carpus extension angle (coefficient: 0.61; CI = 0.4–0.82; P<0.01) and shoulder flexion angle were increased (coefficient: 0.18; CI 0.01–0.33; P<0.05).ConclusionsFetlock extension increased when the horses performed lengthened trot paces, more in extended than medium trot. The loading of the carpus and shoulder were related to fetlock extension, suggesting that lengthened paces affect the loading of the entire forelimb. Lengthened paces may be contraindicated in horses with fetlock hyperextension or suspensory ligament injury; they may be a potential risk factor for these injuries. Interaction with the surface could also have a role that could be further investigated.Ethical animal research: The study was approved by the Animal Health Trust ethical review committee. Owners gave informed consent for their horses' inclusion in the study. Sources of funding: Elise Pilkington Charitable Trust, Dr Wilfrid Bechtolsheimer, British Dressage. Competing interests: None declared.

Clinical conundrum

Claire Bradley at the Animal Health Trust in Newmarket describes the diagnosis and treatment of a Russian Black Terrier presenting with gradual onset of ocular opacities. After initial testing the patient was referred for investigation of underlying causes for hyperlipidaemia.

Diagnosing navicular disease and the role of MRI

Meredith Smith of the Animal Health Trust, discusses how a deeper understanding of the condition can lead to and improved treatment protocol and prognosis

Identification of a novel frameshift mutation in the DMD gene as the cause of muscular dystrophy in a Norfolk terrier dog.

BackgroundA Norfolk terrier was referred to the Animal Health Trust neurology department with suspected dystrophin-deficient muscular dystrophy (DD-MD), which was confirmed by clinical workup and immunohistochemistry.FindingsExon resequencing of the canine Duchenne Muscular Dystrophy (DMD) gene was undertaken to screen for potential disease causing mutations. The sequence data generated from all coding DMD exons revealed a 1 bp deletion in exon 22, causing a frameshift and premature termination of the coding sequence. Gene expression analysis indicated reduced levels of dystrophin transcript in the DD-MD case and western blot confirmed the absence of full length protein.ConclusionsThe finding represents a novel mutation causing DD-MD in the dog.Electronic supplementary materialThe online version of this article (doi:10.1186/s40575-015-0019-4) contains supplementary material, which is available to authorized users.

Equine disease surveillance: quarterly summary

More than 70 UK cases of atypical myopathy reportedFirst reports of Getah virus disease in Japan since 1979Summary of surveillance testing, July to September 2014These are among matters discussed in...

Equine influenza

Adam Rash, research assistant, equine influenza surveillance programme, at the Animal Health Trust, outlines the epidemiology of this ever evolving virus

Equine disease surveillance: quarterly summary

Equine influenza in England and ScotlandSignificant numbers of outbreaks of equine herpesvirus 1 neurological disease in the USASummary of surveillance testing, April to June 2014These are among matters discussed in...

Concurrent Proximal Suspensory Desmopathy And Injury of the Proximal Aspect of the Accessory Ligament of the Deep Digital Flexor Tendon in Forelimbs and Hindlimbs

Reasons for performing studyThere are no reports of proximal suspensory desmopathy (PSD) and concurrent injuries of the proximal aspect of the accessory ligament of the deep digital flexor tendon (ALDDFT).ObjectivesTo describe clinical features, response to local analgesia and ultrasonographic features.Study designRetrospective study.MethodsReview of case records, January 2009–2014.ResultsThere were 8 horses with forelimb lameness, 4 unilateral and 4 bilateral (2 with bilateral injuries of the suspensory ligament [SL] and ALDDFT and 2 with PSD and injury of the ALDDFT in one limb and injury of the ALDDFT alone in the other). One horse had pain on palpation of the proximal aspect of the ALDDFT. Lameness was abolished by palmar metacarpal (subcarpal) nerve blocks in 10/12 limbs; in 2 limbs an ulnar nerve block was required to abolish lameness. There were 5 horses with bilateral hindlimb lameness; concurrent desmopathy of the ALDDFT and PSD was identified in one horse. In the other 4 horses there was a history of bilateral PSD which had undergone treatment. Recurrent lameness was associated with unilateral (n = 3) or bilateral (n = 1) PSD and desmopathy of the ALDDFT. In 2 horses there was soft tissue swelling in the proximomedial aspect of the metatarsus in the region of the ALDDFT. Lameness was abolished by local infiltration of mepivacaine in the proximoplantar aspect of the metatarsus in 3 limbs; in one limb a tibial nerve block was required to eliminate lameness. In all horses lesions were characterised ultrasonographically by enlargement of both the ALDDFT and the proximal aspect of the SL and a diffuse decrease in echogenicity. There was echogenic material between the SL and ALDDFT in 5 limbs.ConclusionsAll soft tissue structures in the proximal aspect of the metacarpus/metatarsus should be evaluated ultrasonographically if pain is localised to this area.Ethical animal research: The study was approved by the Ethical Review Committee of the Animal Health Trust and there was informed owner consent. Sources of funding: None. Competing interests: None.

Mineralisation or Ossification of the Interosseous Ligament of the Centrodistal Joint of the Horse: Is There an Association with Osteoarthritis?

Reasons for performing studyThere have been no detailed descriptions of the radiological appearance of the centrodistal joint interosseous ligament in horses with and without distal hock joint pain.Objectives1) To describe the normal radiological appearance of the region of the centrodistal joint interosseous ligament; 2) to determine the frequency of occurrence of mineralisation or ossification of the interosseous ligament and to describe radiological abnormalities surrounding the interosseous space; 3) to describe concurrent radiological abnormalities in the tarsus. It was hypothesised that ossification of the interosseous ligament will be associated with radiological evidence of osteoarthritis of the centrodistal joint.Study designSystematic radiological analysis using a predefined grading system, after a repeatability study, and descriptive statistics.MethodsCase records and radiographs of all horses which underwent radiographic examination of one or both tarsi over 7 years were reviewed.ResultsThere were 700 horses, including 470 examined bilaterally. The normal interosseous space was an oval‐shaped radiolucent area surrounded by subchondral bone of uniform opacity and thickness. Changes in the region of the interosseous ligament of the centrodistal joint were evident in 190/1170 (16.2%) tarsi, including 50 horses examined bilaterally. In 33/190 (17.4%) tarsi there was complete loss of the oval‐shaped radiolucent area, together with increased thickness of the adjacent subchondral bone, endosteal irregularity and increased opacity of the adjacent trabecular bone. In addition 157/190 tarsi had patchy increased opacity within the interosseous space and alterations of the adjacent subchondral and trabecular bone. There was radiological evidence of osteoarthritis of the centrodistal joint in 27/33 (81.8%) of tarsi with complete ossification of the centrodistal interosseous ligament, 17 of which (51.5%) had distal tarsal pain, and in 29/157 (18.5%) tarsi with other abnormalities of the centrodistal interosseous ligament.ConclusionsWhen evaluating the tarsus radiologically the region of the centrodistal joint interosseous ligament should be assessed.Ethical animal research: The study was approved by the Ethical Review Committee of the Animal Health Trust and there was informed owner consent. Sources of funding: None. Competing interests: None.

Equine disease surveillance: quarterly summary

Equine herpesvirus causing abortion, respiratory disease and neurological diseasePossible historical exposure to West Nile virus in an imported polo ponySummary of surveillance testing, January to March 2014These are among matters...

Focus on: vaccination against equine grass sickness

Jo Ireland of the Animal Health Trust describes a new field trial of a potential vaccine against equine grass sickness

Effect of Pelvic Tilt on Synchronisation and Stability of Riders in Sitting Trot

IntroductionRider movement may influence horse‐rider interaction, yet little is known about what physical attributes affect postural stability. This study aimed to compare pelvic control and postural stability of riders on the floor and whilst riding.Methods33 riders were assessed by a physiotherapist and subjectively graded according to ability to tilt the pelvis in isolation: 1 = poor, 2 = better plus compensations, which were either A = lumbar spine inclusion B = full body lean, 3 = good. Riders wore markers on (1) greater trochanter of the femur, (2) iliac crest, (3) greater tubercle of the humerus. A marker was placed over the horse's tuber sacrale (4). Two‐dimensional high‐speed motion‐capture (240 Hz) recorded four strides of collected sitting trot in a straight line from the left side. Distance between markers was measured at midstance, maximum hindlimb protraction and retraction. Synchronisation was determined by the difference in time (secs) between the tuber sacrale of the horse and pelvis of the rider at these stride points. One‐way ANOVA was used to compare synchronisation between groups. Student's independent t‐test was used to compare marker distance.ResultsFor pelvic tilt, no grade 3 riders were seen. Grade 2 riders were more synchronised with the horse during left hind diagonal suspension phase (P = 0.011) and had smaller horizontal distances between markers 1–2, 2–3 and 1–3 respectively at all points of the stride (midstance: P<0.042; hindlimb protraction: P<0.049; hindlimb retraction: P<0.013). Comparing compensation types, grade A riders were better synchronised with the horse at midstance phase (P = 0.014).ConclusionsResults suggest that control of pelvic movement may have an impact on horse‐rider synchronisation.Ethical Animal ResearchThis project was approved by the Animal Health Trust Clinical Research Ethics Committee. Explicit owner informed consent for participation in this study is not stated. Sources of funding: The Elise Pilkington Charitable Trust, British Dressage and Dr. Bechtolsheimer. Competing interests: none.

Back‐Shape Changes in Sports Horses

IntroductionWe have observed major back‐shape changes over time in some horses, the speed of which may be influenced by work‐type, skeletal maturity, nutrition and saddle‐fit. Currently, there are no longitudinal data quantifying changes in back‐shape and no objective data assessing the importance of each variable. The objectives were to: quantify back‐shape changes over time; describe the effects of age, breed, weight, work‐discipline, saddle‐management and pain elicited on palpation.MethodsPreliminary data from 98 sport horses in regular work in an on‐going one‐year longitudinal study. Weight and management changes were recorded. The thoracolumbar shape was measured at T18, T13 and T8 using a Flexible Curve Ruler [1] every two months. Ratios were calculated for each site for the widths 3 cm and 15 cm ventral to the dorsal midline. Differences in back‐shape were determined using Wilcoxon signed‐rank test. Chi‐square test was used to assess associations between categorical variables, Spearman rank correlation for continuous variables, Mann‐Whitney‐U for continuous variables with binary outcomes and Kruskal‐Wallis to assess ≥3 groups.ResultsT8 and T18‐ratios were significantly different after two months (P<0.001) and T13 after four months (P = 0.004). Decreased ratio at T8 was related to ill‐fitting saddles (P = 0.005), saddles tipping back (P = 0.020), pain on palpation (P = 0.032) and greater age (P = 0.004). Increased T18‐ratio was associated with weight gain (P<0.001), more prevalent in stallions and geldings than mares (P = 0.035) and in dressage horses than other disciplines (P = 0.043).ConclusionsBack‐shape can change within two months, the speed and direction of which are influenced by saddle‐fit, age and bodyweight. Pain elicited on palpation of the back may indicate that changes have occurred. Thus saddle‐fit should be reassessed.Ethical Animal ResearchThe study was approved by the Ethical Review Committee of the Animal Health Trust; there was informed owner consent. Sources of funding: Line Greve is the recipient of a Royal Veterinary College PhD stipend; we acknowledge financial support from World Horse Welfare. Competing interests: none.

Magnetic resonance imaging and foot lameness. Problem solved? Or do we know we know less now that we know more?

Magnetic resonance imaging and foot lameness. Problem solved? Or do we know we know less now that we know more?

New research projects from the Animal Health Trust

New research projects from the Animal Health Trust

Contralateral optic neuropathy and retinopathy associated with visual and afferent pupillomotor dysfunction following enucleation in six cats

To investigate contralateral optic neuropathy and retinopathy following enucleation in 6 cats. Retrospective study. The medical records of cats with contralateral visual and afferent pupillomotor dysfunction following enucleation presented to the Animal Health Trust (AHT), Newmarket, UK, between January 1994 and January 2010 were reviewed. Information recorded included history, signalment, ophthalmic findings, electroretinography (ERG) (2/6) and MRI (3/6) findings and long-term outcome. Pearson's chi-square tests were used to compare breed proportions (P < 0.05). Six cats aged 1.5 to 11 (median 5.5) years presented with mydriasis and/or visual deficits noted immediately following enucleation. Enucleation involved optic nerve (ON) ligation in all of the four cases for which this information was available. Ophthalmic findings included mydriasis with absent pupillary light reflex (PLR) (4/6), incomplete PLRs (2/6), absence of dazzle reflex (4/6) and absence of menace response (4/6). Funduscopy initially revealed multifocal peripapillary retinal lesions, with subsequent progressive optic nerve head (ONH) and retinal atrophy. ERG recordings revealed normal outer retinal function at 6 and 22 weeks (2/2). On MRI, the optic chiasm (OC) ipsilateral to the enucleation could not be identified and the contralateral OC was atrophied (3/3). The acute afferent ON deficits following enucleation, progressive ONH atrophy, normal outer retinal function and MRI demonstrating OC pathology are consistent with chiasmal injury due to traction on the ON during enucleation. Rostral traction on the globe to facilitate ON ligation is contraindicated in cats.

Equine Influenza and Equine Herpesvirus Vaccination: Evaluation of Immune Response and Safety of Concurrent Administration of Equip® FT and Equip® EHV 1,4

AimsThe concurrent administration of EHV1,4 and EIV vaccines is not currently recommended. This study aimed to evaluate safety and immunogenicity of concurrent administration of Equip® FT and Equip® EHV1,4 (treatment group T04) as compared with vaccination with Equip® FT (treatment group T02) or Equip® EHV1,4 (treatment group T03) alone.MethodsEach treatment group included 10 ponies vaccinated on study Days 0 and 42. Immune responses to vaccine antigens were measured on Day 56. Tetanus antibody titres were determined with the toxin binding inhibition test (ToBI). Immunity to equine influenza virus (EIV) induced by vaccination was measured by single radial haemolysis (SRH; antibody response) and IFN gamma assay (a marker of cell‐mediated immunity; CMI). Immune responses to Herpesvirus 1,4 were measured by complement fixation (CF) and IFN gamma assay.ResultsConcurrent administration of EIV and EHV1,4 vaccines was well tolerated. Concurrent administration was proven to be efficacious against tetanus with similar serological immune response of treatment group T04 as compared with T02. Mean SRH results for ponies that received both vaccines were above 85 mm2 for A/eq/Borlange/91 and A/eq/Kentucky/98 antigens, a threshold associated with clinical protection against closely related EIV strains. The highest levels of IFN gamma response were measured in group T02. Although concurrent vaccination seemed to have an effect on both equine herpesvirus (EHV) serology and EHV CMI, EHV results obtained during this study were not conclusive and may have been influenced by a natural EHV‐4 infection occurring prior to study start.Conclusion and practical relevanceConcurrent administration of Equip® FT and Equip® EHV1,4 was well tolerated and induced mean serum antibody levels consistent with clinical protection for tetanus and EIV. However, it was not possible to gather relevant information about the EHV immune response under the conditions of this study.Ethical animal researchThe study was conducted under the Animal Health Trust Home Office Project License and with approval of the Zaventem Ethics Review Assessment team (Zoetis). Sources of funding: The study was sponsored by Pfizer/Zoetis Animal Health. Competing interests: Equip® FT and Equip® EHV1,4 are owned by Zoetis, who sponsored this study. Romain Paillot reports no conflict of interest. All other authors are employed by the study sponsor.

Equine Influenza and Tetanus Immunisation: Evaluation of Antibody Response and Safety of Equip® FT and Equip® F Administration after Reduction of the Primary Course Interval to 3 Weeks

AimsA 6‐week interval is currently recommended during the primary course of the equine influenza (EI) vaccines Equip® FT or Equip® F. This study aimed to evaluate immunogenicity and safety of a 3‐week accelerated interval in order to improve flexibility and to reduce the period of susceptibility to EI virus (EIV) infection.MethodsThree groups of 10 ponies were respectively vaccinated with the vaccine Equip® FT according to the recommended 6‐week V1–V2 interval (T02), Equip® F or Equip® FT according to an experimental accelerated 3‐week interval (T03 and T04, respectively). These groups were boosted (V3) with Equip® F 5 months after V2. Ten ponies in a control group were injected with saline (T01). The antibody response to the vaccine antigens (tetanus toxoid and EIV) were measured 2 weeks after V2 and V3 with the toxin binding inhibition test (ToBI) and single radial haemolysis (SRH), respectively. All animal work received ethical approval.ResultsThe accelerated schedule of immunisation was well tolerated. At both time points, in all vaccinated groups, SRH least squares means for A/eq/Borlange/91 and A/eq/Kentucky/98 antigens were well above 85 mm2, a level described previously to provide clinical protection against homologous EIV strains. Non inferiority of SRH least square means were demonstrated at 2 weeks post V2 for both antigens for T03 and T04, and for A/eq/Kentucky/98 antigen in group T04 after V3. For tetanus,ToBI least squares means were 86.3 iu/mI for T02 and 45.9 iu/ml for T04 after V2 and 2.6 iu/ml for T02 and 2.2 iu/ml for T04 after V3. A level of 0.02 iu/ml has been described as being protective in various publications.Conclusion and practical relevanceA 3‐week accelerated primary course interval was well tolerated and serology results suggested good immunogenicity.Ethical animal researchThe study was conducted under the Animal Health Trust Home Office Project License and with approval of the Zaventem Ethics Review Assessment team (Zoetis). Sources of funding: The study was sponsored by Pfizer/Zoetis Animal Health. Competing interests: Equip® FT is owned by Zoetis, who sponsored this study. Romain Paillot reports no conflict of interest. All other authors are employed by the study sponsor.

New chief executive for the Animal Health Trust

New chief executive for the Animal Health Trust

Improving patient safety in the perioperative period: surgical safety checklists

Surgical complications are an unfortunate part of both medical and veterinary practice, but many are considered to be preventable if appropriate measures are implemented. In human healthcare, one of these measures has been the introduction of surgical safety checklists (SSCs). With proven origins in aviation, another high risk industry, checklists have been linked with the reduction of peri-operative complications and deaths in human hospitals by significant amounts. Recognising that the core values of SSCs are equally applicable to veterinary practice, the Animal Health Trust implemented their use in November 2008. Since then, positive outcomes observed include increased unity among the multiple specialist teams working in the theatre environment and improved communicaiton of vital information regarding individual patients and surgical procedures.