Clinical assessment and grading of back pain in horses

BackgroundThe clinical presentation of horses with back pain (BP) vary considerably with most horse''s willingness to take part in athletic or riding purpose becoming impossible. However, there are some clinical features that are directly responsible for the loss or failure of performance.ObjectivesTo investigate the clinical features of the thoracolumbar region associated with BP in horses and to use some of the clinical features to classify equine BP.MethodsTwenty-four horses comprised of 14 with BP and 10 apparently healthy horses were assessed for clinical abnormality that best differentiate BP from normal horses. The horses were then graded (0–5) using the degree of pain response, muscular hypertonicity, thoracolumbar joint stiffness and overall physical dysfunction of the horse.ResultsThe common clinical features that significantly differentiate horses with BP from non-BP were longissimus dorsi spasm at palpation (78.6%), paravertebral muscle stiffness (64.3%), resist lateral bending (64.3%), and poor hindlimb impulsion (85.7%). There were significantly (p < 0.05) higher scores for pain response to palpation, muscular hypertonicity, thoracolumbar joint stiffness and physical dysfunction among horses with BP in relation to non-BP. A significant relationship exists between all the graded abnormalities. Based on the cumulative score, horses with BP were categorized into mild, mild-moderate, moderate and severe cases.ConclusionsBP in horse can be differentiated by severity of pain response to back palpation, back muscle hypertonicity, thoracolumbar joint stiffness, physical dysfunctions and their cumulative grading score is useful in the assessment and categorization of BP in horses.     

A study of ultrasound-guided perineural injection of the caudal cervical spinal nerve roots in equine cadavers

ObjectivesTo develop an ultrasound-guided cervical perineural injection technique for horses and to evaluate and compare the distribution of contrast agent among perineural, intra-articular and periarticular injections.Study designProspective, experimental cadaveric study.AnimalsA total of 14 equine cadaveric necks.MethodsBilateral ultrasound-guided perineural injection technique for the caudal cervical spinal nerve roots (CSNRs 5–7) was developed. Paramagnetic or iodinated contrast was injected and the distribution of contrast was evaluated using magnetic resonance (MR) or computed tomography (CT) imaging, respectively. The presence of contrast in the CSNR region was determined by an observer unaware of the technique used for each injection performed. The ability of the perineural injection technique to distribute contrast agent to the CSNR region was compared with intra-articular and periarticular injection techniques.ResultsPerineural injection delivered contrast agent to the CSNR region 100% of the time and was significantly different when compared with intra-articular injection (p = 0.008). There was no difference in ability to deliver contrast agent to the CSNR region between the perineural and periarticular injection techniques or between the intra-articular and periarticular injection techniques.Conclusion and clinical relevanceThe ultrasound-guided perineural injection technique developed in this study accurately delivered contrast agent to the CSNR region in equine cadavers. This technique could potentially be used for the diagnosis and treatment of cervical pain in horses, particularly in cases where intra-articular cervical articular process joint injections have not been beneficial. Further studies are necessary to assess the effectiveness of the ultrasound-guided perineural injection technique in live horses.     

Radiographic and scintigraphic evaluation of spondylosis in the equine thoracolumbar spine: A retrospective study

Reasons for performing study: Clinical, radiographic and scintigraphic signs associated with spondylosis of the equine thoracolumbar spine have been poorly documented. Objectives: To establish an objective radiographic and scintigraphic grading system for spondylosis lesions; to estimate the prevalence of spondylosis in a population of horses with back pain; and to compare the results of radiography and scintigraphy Methods: Radiographic images of the thoracolumbar spine from 670 horses with clinical signs of back pain were graded. Scintigraphic images from horses with spondylosis lesions underwent subjective and objective analysis. Sensitivity and specificity of scintigraphy for detection of spondylosis relative to radiography for identification of spondylosis were calculated, and Chi‐squared analysis was performed to test for an association between location and severity of lesions. Results: Twenty‐three of 670 horses (3.4%) with back pain had radiographic evidence of spondylosis. Of these horses, 14 (61%) had more than one lesion and 44% (n = 22) of lesions occurred between T11‐T13 vertebral bodies. Only 33% (n = 28) of locations with radiographic changes had increased radiopharmaceutical uptake. Conclusion: Spondylosis occurs at a low prevalence in horses with back pain. It may be present alone or in association with other osseous abnormalities. The clinical significance of spondylosis needs further investigation. Potential relevance: Spondylosis is uncommon but may be a contributor to back pain in the horse.     

Recognition and quantification of pain in horses: A tutorial review

Pain management is dependent on the quality of the pain evaluation. Ideally, pain evaluation is objective, pain‐specific and easily incorporated into a busy equine clinic. This paper reviews the existing knowledge base regarding the identification and quantification of pain in horses. Behavioural indicators of pain in horses in the context of normal equine behaviour, as well as various physiological parameters potentially useful for pain evaluation, are discussed. Areas where knowledge is sparse are identified and a new equine pain scale based on results from all reviewed papers is proposed. Finally, the most important considerations in relation to the implementation of a pain scale in a hospital setting are discussed.     

Evaluation of the practical clinical use of the Horse Grimace Scale translated into French

ObjectiveTo assess the reliability of a French version of the Horse Grimace Scale (HGSfv).Study designProspective, randomized, clinical study.AnimalsThe operated (OP) group included 13 horses undergoing elective surgery. The positive (PC) and negative control (NC) groups included seven colicking horses and eight exercising sport horses, respectively.MethodsPhotographs were extracted from videos of the horses’ heads. Videos were taken before and immediately after surgery in OP, on arrival of the horse in PC, and at rest in their stalls in NC. Pictures were evaluated by three anaesthetists [Diplomates (DIPs)] and four riders (RIDs) using Horse Grimace Scale translated into French (HGSfv) at two points, 2 weeks apart (E1 and E2). Each evaluator gave each image a score (1–3) for six identified facial action units. The scores given by DIPs and RIDs were compared using a Wilcoxon test. Intra- and inter-evaluator reliability were assessed using Spearman correlation tests (r_s) and intra-class coefficients (ICCs), respectively.ResultsRIDs and DIPs gave significantly higher scores in the PC group than in the NC group [RIDsE1PC 5.0 (4.2–9.8) versus RIDsE1NC 2.2 (0.0–6.5), p = 0.02; RIDsE2PC 5.2 (3.2–9.5) versus RIDsE2NC 2.0 (0.2–5.8), p < 0.01; DIPsE1PC 4.0 (1.3–6.3) versus DIPsE1NC 2.2 (1.0–4.7), p = 0.04; DIPsE2PC 2.7 (1.0–6.0) versus DIPsE2NC 1.0 (0.0–2.3), p = 0.03]. Scores given by RID or DIPs 2 weeks apart were highly correlated [r_s (RIDsE1, RIDsE2) r = 0.86, p < 0.0001] and [r_s (DIPsE1, DIPsE2) r = 0.81 p < 0.0001]. The ICC between RIDs and DIPs in E1 and E2 was 0.94 (0.92–0.95) and 0.91 (0.89–0.93), respectively. The specificity and sensitivity of the HGSfv was 94% and 43%, respectively.Conclusions and clinical relevanceUsing the HGSfv, knowledge of horses rather than specialization in veterinary anaesthesia and analgesia appears to differentiate horses with visceral pain from those assumed to be pain free.     

Analgesic efficacy of intra‐articular morphine in experimentally induced radiocarpal synovitis in horses

ObjectiveTo compare the analgesic effect of intra-articular (IA) and intravenous (IV) morphine in horses with experimentally induced synovitis.AnimalsEight adult horses.Study designRandomized, observer blinded, double dummy trial with sequential crossover design.MethodsRadiocarpal synovitis was induced by IA injection of lipopolysaccharide on two occasions separated by a 3-week washout period. In one study period horses received treatment IA; morphine IA (0.05 mg kg^?1) plus saline IV and in the other study period they received treatment IV; saline IA plus morphine IV (0.05 mg kg^?1). Lameness and pain were evaluated repeatedly by two observers throughout each of the two 168-hour study periods. Pain was evaluated by use of a visual analogue scale of pain intensity (VAS) and a composite measure pain scale (CMPS). Comparison of treatments was performed by analysis of variance with repeated measurements. Significance level was set to p ≤ 0.05. Inter-observer agreement and agreement between the VAS and CMPS was assessed by use of the Bland–Altman method.ResultsIntra-articular injection of LPS elicited a marked synovitis resulting in lameness and pain. IA morphine resulted in significantly less lameness than IV morphine (p = 0.03). CMPS (p = 0.09) and VAS (p = 0.10) pain scores did not differ significantly between treatments. Inter-observer agreement of the CMPS was classified as good, but only fair for the VAS. Agreement between the two pain scales was considered fair.Conclusions and clinical relevanceAn analgesic effect of IA morphine was demonstrated by significantly reduced lameness scores. The results support the common practice of including IA morphine in a multimodal analgesic protocol after arthroscopic surgery, although further studies in clinical cases are needed. The employed CMPS had good reproducibility, and was easy to use, but may have limited sensitivity at mild intensity pain.     

Preliminary evaluation of subjective scoring systems for assessment of postoperative pain in horses

This study examined the performance of two subjective pain scoring systems for evaluating equine postoperative pain, and investigated differences in pain scoring tendencies of veterinarians and grooms. Fifteen horses were included in the study. Group 1 (n = 8) had chronic lameness and was admitted for elective arthroscopy under general anaesthesia, on one or two femoropatellar, femorotibial or tibiotarsal joint or digital flexor tendons. The anaesthetic protocol for each horse was similar but not standardized. Multi‐modal peri‐operative analgesia comprised: romifidine (100 µg kg^?1 IV); flunixin (1.1 mg kg^?1 IV); ketamine (2.2 mg kg^?1 IV); morphine (0.12 mg kg^?1 IV); phenylbutazone (4 mg kg^?1 IV/PO). Group 2 (n = 7) included pain free controls. At 6 hours post‐recovery from anaesthesia (PR) (group 1) or at 20.00 hours (group 2 with one limb bandaged), horses were filmed undisturbed in their stables for 90 seconds (dynamic behaviour, DB); thereafter, the surgery site and pharynx of each horse were palpated (and filmed) in a standardized manner (interactive behaviour, IB). Two observer groups, seven veterinarians and eight grooms, watched video footage of each horse and assigned pain scores using a visual analog scale (VAS) and a numerical rating scale (NRS). Observers assigned a pain score (VAS and NRS) for DB and IB separately and overall. Statistical analysis (Minitab 13.0, Wilcoxon signed rank and Mann–Whitney U‐tests) investigated differences in pain scores attributed to groups 1 and 2 horses, compared pain scores assigned by veterinarians and grooms, and examined differences in the performance of VAS and NRS techniques. There were significant differences in the pain scores assigned by veterinarians and grooms to groups 1 and 2 horses. When using DB or IB separately (but not combined) to score perceived pain, grooms assigned higher scores to group 1 than group 2 (U = 81.5, p < 0.05; U = 82.0, p < 0.05) using the VAS. There was no difference in NRS scores attributed by grooms to groups 1 and 2. Using DB and IB separately or combined, there was no difference in pain scores attributed to groups 1 and 2 by veterinarians using either VAS or NRS scoring systems. Using separate VAS scores for DB (W = 32.5, p < 0.05) and IB (W = 26.5, p < 0.05) and using combined (DB + IB) VAS scores, grooms awarded higher pain scores (W = 27.0, p < 0.05) than veterinarians to group 1. Using the NRS, vets and grooms did not score pain differently for group 1. For group 2, grooms scored pain significantly higher than vets when using the VAS to score IB separately (W = 21.0, p < 0.05); no other differences between grooms and veterinarians in pain scoring of group 2 (NRS or VAS, DB and IB separately or combined) were identified. The performance of subjective pain scoring systems for assessment of equine postoperative pain varies according to the scale used, the behaviour evaluated (dynamic or interactive) and the observer group. While data suggest that grooms distinguished post‐surgery horses from controls more successfully than vets and assigned higher pain scores to these horses, the specific behavioral criteria on which scores were assigned requires future investigation and identification.     

Isolation of equine herpesvirus type 5 in New Zealand

Aim. To report the first isolation of equine herpesvirus 5 (EHV-5) in New Zealand as part of a study of equine respiratory viruses in New Zealand.

Methods. Nasal swabs and peripheral blood leukocytes were collected from 114 foals and adult horses, inoculated on to equine fetal kidney, rabbit kidney and Vero cell lines and observed for cytopathic effect. EHV-5 isolates were identified using an EHV-5 specific polymerase chain reaction. All samples positive for EHV-5 were also checked for the presence of EHV-2, EHV-1 or EHV-4 DNA using published type-specific primers. The polymerase chain reaction results were further confirmed by dot blot and Southern hybridisation with specific DIG-labelled probes.

Results. EHV-5 was isolated from nasal swabs or peripheral blood leukocytes of 38 out of 114 horses sampled. From horses sampled more than once, EHV-5 was often isolated on more than one occasion. Most of the horses were infected with both EHV-2 and EHV-5 viruses. It was not possible to make an association between EHV-5 isolation and the presence of respiratory disease.

Conclusion. EHV-5 is present in the New Zealand horse population. The exact role it plays in causing, or predisposing to, respiratory disease remains to be elucidated.     

Dynamic respiratory endoscopy without treadmill in 68 performance Standardbred,Thoroughbred and saddle horses under natural training conditions

Reasons for performing study: High speed treadmill endoscopy provides a true assessment and diagnosis of the dynamic obstructions of the upper equine respiratory tract (DO‐URT). However, treadmills do not always allow reproduction of the exact conditions of dynamic collapse of the URT. The availability of on‐board endoscopes, which could be used without a treadmill, would make exercising endoscopy readily available to more equine practices. Objectives: To develop and validate an innovative endoscope which could be used for the examination of the URT at exercise in ridden and harnessed sport horses performing in natural conditions. Methods: Authors worked closely with engineers of a company manufacturing veterinary endoscopes. Over a 2‐year period several prototypes were tested on more than 20 cooperative horses performing either in trot, gallop, jumping or endurance. The final Dynamic Respiratory Scope (DRS) allows real‐time visualisation of the URT and video recordings for post test reviewing and archiving. The DRS was then tested in 2 equine livery yards. Performance horses presented for investigation of abnormal respiratory noises at exercise and/or poor performance were subjected to exercising endoscopy. Endoscopic images of the URT were recorded and video recordings of the URT were reviewed post test. Results: A total of 68 horses were examined: 39 harnessed Standardbred and 29 mounted horses (16 Thoroughbred and 13 saddle horses). Of these, 44 were diagnosed with a URT abnormality. Good quality videos were obtained even at maximum speed in all cases. The innovative insertion tube provided very stable images compared to those obtained with flexible video endoscopes on treadmills. Conclusions: This study validates the safety and the reliability of the DRS for imaging the equine URT during natural exercising conditions. Potential relevance: Most common causes of DO‐URT can be diagnosed easily during any type of performance without a treadmill and the DRS offers a great potential for further URT clinical research.     

Development of a technique for continuous perineural blockade of the palmar nerves in the distal equine thoracic limb

Objective To develop a technique for placing continuous peripheral nerve block (CPNB) catheters adjacent to palmar nerves in horses and to evaluate the effect of low‐volume local anesthetic (LA) infusion on nociception in the distal equine thoracic limb. Study design In vitro and in vivo laboratory investigation. Study material and animals Forty‐two thoracic limbs from 22 equine cadavers and five horses. Methods Thoracic limb specimens were dissected to find landmarks for catheter insertion adjacent to medial and lateral palmar nerves. Based on the anatomy of the proximal metacarpus, a technique for placing palmar CPNB catheters was developed and the potential for catheter dislodgement studied in vitro by fluoroscopic visualization during passive carpal flexion and dye injection following simulated limb motion. The feasibility of CPNB catheter instrumentation in standing, sedated horses was tested in five animals, with ultrasound control. Electrical and mechanical stimulation thresholds and response latencies for hoof withdrawal responses (HWR) were determined following saline or LA infusion. Results Medial and lateral CPNB catheters were inserted percutaneously 2 and 4–5 cm, respectively, distal to the accessory carpal bone and advanced for ～7 and 10 cm, respectively, to place the tip just proximal to the communicating branch of the nerves. Catheters were placed correctly in 88% and 85% of cadaver limbs. In the standing horses, LA infusion not only increased HWR thresholds and latencies to noxious mechanical or electrical stimulation but also caused vasodilation and limb swelling over time. Conclusion The technique, developed in vitro, for placing and maintaining palmar CPNB catheters in the equine thoracic limb was successfully applied in vivo. Catheters were well tolerated but LA infusion may cause limb swelling, suggesting a need for further exploration of drug and infusion regimens. Clinical relevance Continuous perineural LA infusion along palmar nerves may develop into an effective analgesic technique in horses suffering from lower limb pain.     

Prevalence of antibodies to equine viruses in the Netherlands

Summary

The prevalence of antibodies to various viruses was investigated in a series of serum samples collected from horses in the Netherlands between 1963 and 1966 and from 1972 onwards. Neutralizing antibodies to equine rhinopneumonitis virus, equine arteritis virus and to equine rhinovirus types 1 and 2 were detected in respectively 76%, 14%, 66% and 59% of the equine serum samples tested.

The observed incidence of serum samples positive to equine adenovirus in the complement fixation test was 39%. Precipitating antibodies to equine infectious anaemia virus were detected only in serum samples from two horses imported from abroad. Haemagglutination inhibiting antibodies to Myxovirus influenzae A / equi‐1, M. Influenzae A / equi‐2, and Reovirus types 1, 2, and 3 were present in respectively 82%, 50%, 10%, 33% and 3.6% of the serum samples tested.

The most frequently observed incidence of antibodies to the various equine respiratory viruses occurred in the groups of horses having repeatedly contact with other horses.     

Preliminary evaluation of a behaviour-based system for assessment of post-operative pain in horses following arthroscopic surgery

Objective To develop a method for objective assessment of equine post‐operative pain. Study design Prospective nonblinded clinical study. Animals Twelve adult horses: Group 1 (G1, n = 6), admitted for arthroscopy (under general anaesthesia, with multimodal analgesia); Group 2 (G2, n = 6), ‘pain free’ controls. Materials and methods Horses were filmed continuously (CVI, time‐lapse video recorder) over 72 hours, from 24 hours pre‐surgery (PS) to 48 hours post‐recovery (PR) (G1), and over 24 hours (G2). Activity budgets were determined from 24 to 0 hours PS, 0–24 and 24–48 hours PR (G1) and for 24 hours (G2). Using direct observation (DO), active behaviours and postures were recorded at set time points PS and PR (G1) and at two time points (morning/evening) (G2). Heart rate (HR) and respiration rate (RR) were recorded simultaneously. Statistical analysis investigated within‐group and between‐group time‐related changes in behaviour, HR and RR. Results There was no difference in HR or RR between G1 and G2 at any time point. Anaesthetic ‘hangover’ and hunger‐related activity modulated behaviour from 0 to 6 hours PR, when abnormal postures and locomotion occurred in all G1 horses, but no G2 horses. Compared with G1 (0–24 hours PR), G2 spent more time eating (t = ?3.34, p < 0.01), more time at the front of the stable (t = ?2.42, p < 0.05), and less time exhibiting ‘abnormal’ behaviour (U = 56, p < 0.01). Comparing PS and PR behaviour, G1 spent less time exploring from 24 to 48 hours PR (t = 3.49, p < 0.05), less time in sternal recumbency (t = ?3.8, p < 0.05) and less time moving (t = 3.19, p < 0.05). Horses tended (p < 0.07) to spend less time positioned in the front of the stable PR (less from 24 to 48 hours PR than from 0 to 24 hours PR). Comparing PR (evening) behaviour, G2 spent more time with head above withers (U = 21.5, p < 0.01), and ears forwards (U = 22, p < 0.01). G1 showed time‐related changes (all p < 0.05) in time with lower lip tense (S = 15.8), eating (S = 17.08) and with head positioned above withers (S = 18.04). No differences in event behaviours were observed between G1 and G2. Within G1, only olfactory behaviour varied significantly with time (S = 14.52, p < 0.05). Conclusions Changes in equine behaviour suggestive of post‐operative discomfort were identified using both DO and CVI. Analysis of activity budgets may be a more sensitive method of identifying behavioural changes indicative of equine discomfort than repeated DO of specific events and postures.     

Efficacy of orally administered gabapentin in horses with chronic thoracic limb lameness

ObjectiveTo evaluate the analgesic effects of orally administered gabapentin on horses with chronic thoracic limb lameness.Study designRandomized, crossover design.AnimalsA total of 14 adult horses with chronic thoracic limb lameness.MethodsFollowing baseline measurement of lameness, horses were administered each of four treatments orally in grain: treatment G, gabapentin (20 mg kg^–1) twice daily for 13 doses; treatment F, firocoxib (171 mg once, then 57 mg once daily for six doses); treatment GF, gabapentin and firocoxib at previously stated doses and frequencies; or treatment C, grain only as a control. Treatments were administered in a randomized, crossover design, separated by 2 weeks. Subjective lameness score (SLS), inertial sensor vector sum (VS) calculations, peak vertical ground reaction force (PVGRF) measurements and vertical impulse (VI) calculations were determined immediately prior to each initial treatment dose and 2–4 hours after the final treatment dose for each treatment. Mean change in SLS, VS, PVGRF and VI for each treatment were compared among treatments.ResultsThe rank change in SLS of treatment GF was significantly greater than that of treatments C (p = 0.01) and G (p = 0.01) but not of treatment F (p = 0.08). No differences in VS (p = 0.4), PVGRF (p = 0.4) or VI (p = 0.1) were observed among treatments.Conclusions and clinical relevanceGabapentin, as administered here, did not improve subjective or objective measures of lameness in horses with chronic thoracic limb musculoskeletal pain. Although subjective evaluation identified an improvement in lameness with treatment GF, it was not different from that observed with treatment F. Higher oral dosing and longer treatment regimens of gabapentin may be indicated for the treatment of chronic musculoskeletal pain in horses.     

The effect of stimulus height on visual discrimination in horses

This study investigated the effect of stimulus height on the ability of horses to learn a simple visual discrimination task. Eight horses were trained to perform a two-choice, black/white discrimination with stimuli presented at one of two heights: ground level or at a height of 70 cm from the ground. The height at which the stimuli were presented was alternated from one session to the next. All trials within a single session were presented at the same height. The criterion for learning was four consecutive sessions of 70% correct responses. Performance was found to be better when stimuli were presented at ground level with respect to the number of trials taken to reach the criterion (P < 0.05), percentage of correct first choices (P < 0.01), and repeated errors made (P < 0.01). Thus, training horses to carry out tasks of visual discrimination could be enhanced by placing the stimuli on the ground. In addition, the results of the present study suggest that the visual appearance of ground surfaces is an important factor in both horse management and training.     

Application of a Composite Pain Scale to Objectively Monitor Horses with Somatic and Visceral Pain under Hospital Conditions

Pain recognition and management in animals has advanced considerably in the last decade and currently animal welfare is receiving increasing public interest. However, the comprehensive assessment of pain has been inadequately addressed in horses and till recently composite pain scales (CPSs) have hardly been validated for use in patients. We investigated the reliability and clinical applicability of a CPS, originally developed under experimental conditions for assessing pain in horses with various acute soft-tissue and orthopedic conditions before and after general anesthesia and/or (non)elective surgery. These clinical cases (n = 94) were scored by means of the CPS twice daily. Horses without painful conditions and horses admitted for nonpainful diagnostic procedures under general anesthesia were compared with those that were admitted with either acute or chronic surgical and nonsurgical painful conditions of both visceral and somatic origin. Scores of observer 1 were compared with observer 2 to study inter-observer reliability. Composite pain scores showed low baseline values in healthy animals with nonpainful conditions and were not affected when general anesthesia was the only intervention. Inter-observer reliability was very high (n = 23 horses; weighted kappa correlation coefficient, κ = 0.81). Horses with painful conditions responding well to analgesic treatment could be discriminated from horses that had to be euthanized on humane grounds because of painful nonresponsive conditions. We found the CPS to be a promising tool that has the potential to provide a good basis for direct day-to-day assessment of pain status in equine patients with various painful conditions in the future.     

Computed tomographic features of the temporomandibular joint in 10 Jeju horses

BackgroundThe equine temporomandibular joint (TMJ) has a complex anatomical structure that makes diagnosis of TMJ disorders difficult. Computed tomography (CT) is now available in equine medicine; hence, TMJ evaluation has become more convenient.ObjectivesThe objectives of this study were to describe the CT features of the TMJ in Jeju horses and to compare these features with those of Thoroughbreds.MethodsIn this report, the TMJs of 10 Jeju horses (mean age: 4.5 ± 1.9 yr; mean body weight: 282.6 ± 40.3 kg) and 6 Thoroughbreds (mean age: 7.3 ± 1.6 yr; mean body weight: 479.7 ± 44.0 kg) were examined using CT. After CT scanning, the Hounsfield units (HU) and height to width ratio (H:W) of the mandibular condyle were measured.ResultsThe mean H:W in Jeju horses was significantly lower than that in Thoroughbreds. The mean HU in Jeju horses was lower than that in Thoroughbreds; however, the difference was not significant. The most frequent CT finding was an irregular medial margin of the mandibular condyle in both breeds.ConclusionsIn this study, the shape of the mandibular condyle in Jeju horses was flatter than that in Thoroughbreds. This report could be useful in evaluating the TMJ in Jeju horses. Moreover, CT could be a pragmatic choice for the examination of the TMJ in horses.     

Comparison of pain on injection during induction of anaesthesia with alfaxalone and two formulations of propofol in dogs

ObjectiveTo compare the incidence of pain during injection of three intravenous induction agents in dogs.Study designProspective, crossover, randomized, blinded, clinical study.AnimalsThirty dogs requiring anaesthesia for radiotherapy.MethodsDogs were anaesthetized on three occasions at weekly intervals. An IV cephalic catheter was placed, flushed with saline and alfentanil 0.01 mg kg^?1 and atropine 0.02 mg kg^?1 administered. After 30 seconds either: propofol lipid macroemulsion (Drug_P), propofol lipid-free microemulsion (Drug_PC) or alfaxalone (Drug_A) was administered over 60 seconds. Each induction agent was administered once to each dog. Induction was recorded by video and reviewed by an assessor, unaware of treatment. Catheter placement (number of attempts, site, size and recent vein use) were recorded. Behavioural changes associated with pain or excitation, were recorded. Severity of pain on injection was recorded (mild, moderate or severe pain). Incidence of pain was analysed using logistic regression, excitation using McNemar's test (p < 0.05) and association of pain with induction agent and catheter placement using the Akaike Information Criterion (AIC).ResultsNo dogs reacted to saline or Drug_A, thus Drug_A was excluded from analysis. Pain on injection occurred in six dogs (20%) with Drug_PC and one dog (3.3%) with Drug_P. Pain was severe in four dogs with Drug_PC. Drug_P resulted in a trend for reduced risk of pain compared to Drug_PC (p = 0.076, odds ratio [confidence intervals] 0.14 [0.027–0.86]). Both propofol formulations resulted in greater risk of excitation than Drug_A (p = 0.0003, odds ratio 4.5 [1.86–10.90]). Induction agent was associated with pain, whilst catheter placement was not. One dog developed facial oedema and one other dog skin necrosis adjacent to the catheter site following Drug_PC. The study was terminated early due to ethical concerns about the severity of reactions with Drug_PC.Conclusions and Clinical relevanceDrug_PC was associated with clinically relevant moderate to severe pain behaviour whilst Drug_A and Drug_P were not.     

Use of rotational periosteal flaps in primary repair of sinofacial fractures in seven horses

ABSTRACT

Case history: Medical records were reviewed of horses (n?=?7) undergoing surgery for fracture of one or more facial bones extending into the paranasal sinuses that was repaired primarily within 24 hours of the time of injury using a rotational periosteal flap, between April 2009 and May 2017. A kick from another horse was the cause of the injury of three horses, and one horse was injured when it collided with a tree. The cause of the injury of three horses was unknown.

Clinical findings and treatment: Fractures were of the right maxillary bone in two horses, the left maxillary bone in two horses, the left frontal and left nasal bones in two horses, and the right frontal bones in one horse. The fracture of all but one horse was accompanied by an open wound. The fracture of all seven horses was reduced, stabilised, and covered with a rotational, periosteal flap. Surgery was carried out while standing in six horses, and while anesthetised in one horse. All horses had a deficit in the fractured facial bones after the fracture was reduced. Four horses had complications following surgery, but all horses were reported to have excellent cosmetic outcomes and had retuned to their previous level of activity, as reported by their owners.

Clinical relevance: Covering a primarily repaired sinofacial fracture of a horse with a rotational periosteal flap resulted in good cosmetic outcomes, and may be especially beneficial if the fracture is accompanied by loss of bone.     

Relationship of heart rate and electrocardiographic time intervals to body mass in horses and ponies

ObjectivesTo investigate the relationship of heart rate (HR) and ECG time intervals to body weight (BWT) in healthy horses and ponies. We hypothesized that HR and ECG time intervals are related to BWT.Animals250 healthy horses of >30 breeds; 5.5 (1–30) y [median (range)]; 479 (46–1018) kg.MethodsProspective study. Standard base-apex ECGs were recorded while the horses were standing quietly in a box stall. Mean HR over 15 s was calculated and RR interval, PQ interval, QRS duration, and QT interval were measured by a single observer.QT was corrected for differences in heart rate using Fridericia's formula (QT_cf = QT/³√RR). The relationship between ECG variables and BWT, age, sex, and RR interval was assessed using multivariate backward stepwise regression analyses. Goodness of fit of the model was improved when using log(BWT) compared to BWT. Body weight was overall the strongest predictor of HR and ECG time intervals. Therefore, only log(BWT) was included as an independent variable in the final model. The level of significance was p = 0.05.ResultsHR (R² = 0.21) showed a significant negative relationship and PQ (R² = 0.53), QRS (R² = 0.23), QT (R² = 0.14), and QT_cf (R² = 0.02) showed significant positive relationships to log(BWT).ConclusionsSmall equine breeds undergoing routine ECG recordings have slightly faster heart rates and shorter ECG time intervals compared to larger equine breeds. Although the magnitude of absolute differences may be small, body weight needs to be considered among other factors when comparing HR and ECG time intervals to normal ranges in horses.     

Quantitative assessment of increased sensitivity of chronic laminitic horses to hoof tester evoked pain

Reasons for performing study: To evaluate quantitative sensory testing (QST) of the feet of laminitic horses using a power‐assisted hoof tester. Hypothesis: Hoof Compression Thresholds (HCTs) can be measured reliably and are consistently lower in horses with chronic laminitis than in normal horses. Methods: HCTs of chronic laminitic (n = 7) and normal horses (n = 7) were repeatedly measured using a hydraulically powered and feedback controlled hoof tester. Data from 2 tests, at 3 sites in both forefeet, during 3 sessions were collected and statistically analysed using linear mixed models. Results: The mean ± s.e. HCT for the laminitic horses was 29.6 ± 3.5 kg/cm² and for horses in the normal group was 59.8 ± 4.3 kg/cm². Residual variance was the largest of the error components and was greater (P<0.001) for the normal horses; none of the other components significantly differed between the 2 groups. Averaging of HCTs from each foot could produce a test with intraclass correlation coefficients of 0.83 for the normal group and 0.87 for the laminitic group, with an estimated sensitivity of 0.94 and a specificity of 0.93. This test would permit detection with 80% power and 95% confidence of a reduction of over 40% in the difference in mean HCTs between laminitic and normal horses following effective treatment provided that the experimental groups are of 9 or more horses. Conclusions: HCTs can be safely and reliably measured experimentally using this hoof tester. The level of variability found indicates that, under these conditions, treatments may need to produce at least a 40% improvement to be detected. Simplification of the hoof tester, training of the horse and repeated testing may permit the method to be used clinically to detect changes in the HCTs of individual laminitic horses but these potential improvements will require further investigation. Potential relevance: Measurement of HCTs can provide an additional means for assessing the effectiveness of treatments for alleviation of chronic equine laminitis.