Pain assessment in horses after orthopaedic surgery and with orthopaedic trauma.

Objective pain assessment is important to guide and tailor therapy in clinical practice. This study describes the clinical applicability and validity of two pain scales, the Composite Pain Scale (CPS) and the Equine Utrecht University Scale for Facial Assessment of Pain (EQUUS-FAP) in horses with orthopaedic trauma or after orthopaedic surgery. A cohort follow-up study was performed using 77 adult horses (n=43 with orthopaedic trauma or injury; n=34 controls). Composite and facial expression-based pain scores were assessed by direct observations of pairs of two independent observers. All horses were assessed at arrival, and on the first and second day after arrival or after surgery. Both CPS and EQUUS-FAP scores demonstrated high inter-observer reliability (Crohnbach's alpha=0.97 for CPS; Crohnbach's alpha=0.93 for EQUUS-FAP; P<0.001), with low bias (0.07 and -0.08 respectively) and limits of agreement of -1.9 to 1.9 for CPS and -1.9 to 1.9 for EQUUS-FAP. Both CPS and EQUUS-FAP scores showed significant differences between control horses and orthopaedic cases (P<0.001). Trauma cases had significantly higher pain scores compared to postoperative cases for both CPS (P<0.05) and for EQUUS-FAP (P<0.01) and both pain scores significantly decreased after nonsteroidal anti-inflammatory drug (NSAID) administration. In accordance with the findings in other types of equine pain, the CPS and FAP proved useful and valid for objective and repeatable assessment of pain in horses with orthopaedic trauma or after orthopaedic surgery. This can further aid treatment of horses in clinical practice and might improve equine welfare.

Objective pain assessment in horses (2014-2018).

In recent decades, much effort has been invested in scientific studies of objective and reliable assessment of pain in horses. Various types of pain assessment tools have been described and (partly) validated for different types of pain in horses. Currently, composite pain scales and facial expression-based pain scales seem to be the most promising tools for pain assessment in horses and numerous studies have recently been published on the use of these pain scales in horses. Therefore, this narrative review mainly focusses on these two types of pain scales and on the studies that have appeared describing these type of pain scales in horses. The extent to which these pain scales have been validated (sensitivity, specificity, inter-observer reliability etc.) and their potential use for clinical pain states is discussed. Possible future directions for new studies and their possible aid in assessing pain in hospitalised and ridden horses are presented. In this way, improved pain scoring could improve criteria used to evaluate the clinical efficacy of new analgesic drugs and techniques, potentially benefiting equine welfare.

Quantitative and qualitative aspects of standing-up behavior and the prevalence of osteochondrosis in Warmblood foals on different farms: could there be a link?

BACKGROUND: Osteochondrosis (OC) is a common, clinically important joint disorder in which endochondral ossification is focally disturbed. Reduced blood supply to growing cartilage is considered an important cause of the condition, which has both genetic and environmental origins. Housing conditions can influence cartilage injury through peak-pressure changes during limb sliding. Additionally, circulatory perturbation can cause the avascular necrosis of cartilage. In this study, we evaluated the type and frequency of limb sliding during standing up and the occurrence of OC in foals aged up to 12 months on different farms. METHODS: Standing-up behavior was observed in 50 weaned, group-housed, Dutch Warmblood foals aged 6-9 months at five farms using black-and-white surveillance cameras, and their standing-up behavior was scored using a predetermined ethogram. OC was scored using a categorical scale between 6 and 12 months of age in 50 foals in the weanling period, and in 48 from the weanling to yearling periods because two foals died in this time. RESULTS: At both 6 and 12 months of age, the total prevalence of OC differed between the farms: the lowest prevalence was observed on a farm with no sliding, and the highest prevalence was evident on a farm with a higher sliding frequency. The mean ratio of sliding versus normal standing-up behavior was 29% (range: 0-50%); i.e., foals experienced limb sliding during around 29% of standing-up maneuvres. The frequency of sliding instead of normal standing-up behavior differed significantly between the farms (range: 0-50%; P < 0.05), but significantly decreased when foals could better prepare themselves to stand, e.g., when there was an obvious provocation such as the announced approach of another foal (P < 0.05). CONCLUSIONS: Small but significant differences exist between farms in the sliding frequency and total OC incidence in Warmblood foals, but whether environmental factors are causally related to these differences requires further elucidation.

Effect of different head and neck positions on behaviour, heart rate variability and cortisol levels in lunged Royal Dutch Sport horses.

Different head-and-neck positions (HNPs) are discussed in relation to potential welfare issues. To evaluate the effect on welfare, seven Royal Dutch Sport horses were studied in five predetermined HNPs: (1) unrestrained (HNP1); (2) neck raised, bridge of nose around the vertical (HNP2); (3) neck lowered and considerably flexed, bridge of nose pointing towards the chest (HNP4); (4) neck raised and extended, bridge of nose in front of the vertical (HNP5), and (5) neck lowered and flexed, bridge of nose pointing towards the carpus (HNP7). A standardised exercise test (SET) of 34 min consisted of trot, canter and walk. Behaviour was recorded with a pre-defined ethogram and R-R intervals measured using telemetry. Cortisol concentrations were taken at the start, 5 and 30 min after the SET. Behaviour around the SET was scored separately. Conflict behaviours increased significantly during HNP2 when compared with HNP1, HNP4 and HNP7 during the SET, and there was significant negative anticipation before HNP2 and HNP7. The heart rate variability (HRV) frequency domain for HNP2 showed a significantly increased low frequency peak (LFpeak) compared with other HNPs, and there was a decrease in very low frequency (VLF%) compared with HNP1. HNP4 showed a significant increase in LF% and decrease in VLF% compared with HNP1. Saliva cortisol concentrations were significantly increased in HNP2 at 5 and 30 min after exercise. Increased conflict behaviour was mostly observed in HNP2, but there was a raised HRV suggesting a sympathetic shift in HNP2 and HNP4, and increased cortisol concentrations during HNP2 indicated a stress response.

Lateralised motor behaviour leads to increased unevenness in front feet and asymmetry in athletic performance in young mature Warmblood horses.

REASON FOR PERFORMING STUDY: Foot stance in grazing significantly influences hoof conformation and development from foal to yearling age. OBJECTIVES: To conduct a longitudinal study to establish if the relationship between motor laterality and uneven front feet persisted in 3-year-old horses at the time of studbook selection and to investigate if such laterality and unevenness might influence the horses' ability to perform symmetrically while trotting, cantering and free jumping. METHODS: Seventeen clinically sound but untrained (with only minimal experience of handling) and sound Warmblood horses that had participated in a previous study were assessed as per the protocol reported. Laterality was tested in a preference test (PT) and z-values were calculated for analysis purposes. Laterality and hoof unevenness were related to both relative limb length and relative head size, while the ability to perform symmetrically was tested in free trot-canter transitions and free jumping exercises. Differences in performance between horses with and without a limb preference in the PT and those with 'uneven' and 'even' feet were tested for differences in performance metrics using Students' t test, while linearity was tested using a regression analysis (P<0.05). RESULTS: Significant laterality was still present in 24% of the 3-year-old horses and the relationship between laterality and uneven feet pairs was stronger than at foal and yearling stages. Horses with significant motor laterality had almost 4 times more unevenness, a smaller head and longer limbs and the relationship between body conformation and laterality was still present. There was a strong linear relation between unevenness, laterality and a bias or side preference for trot-canter transitions. However, this relationship was not significant during the free jumping exercise. CONCLUSION: Motor laterality and uneven feet pairs were still present and significantly related in the 3-year-old horses and both variables were also strongly related to sidedness in trot-canter transitions. POTENTIAL RELEVANCE: Warmblood studbooks should include quantitative data on laterality at the time of studbook admission as part of the selection criteria.

Uneven feet in a foal may develop as a consequence of lateral grazing behaviour induced by conformational traits.

REASONS FOR PERFORMING STUDY: Conformational traits are important in breeding, since they may be indicative for performance ability and susceptibility to injuries. OBJECTIVES: To study whether certain desired conformational traits of foals are related to lateralised behaviour while foraging and to the development of uneven feet. METHODS: Twenty-four Warmblood foals, born and raised at the same location, were studied for a year. Foraging behaviour was observed by means of weekly 10 min scan-sampling for 8 h. A preference test (PT) was developed to serve as a standardised tool to determine laterality. The foals were evaluated at age 3, 15, 27 and 55 weeks. The PT and distal limb conformation were used to study the relation between overall body conformation, laterality and the development of uneven feet. Pressure measurements were used to determine the loading patterns under the feet. RESULTS: About 50% of the foals developed a significant preference to protract the same limb systematically while grazing, which resulted in uneven feet and subsequently uneven loading patterns. Foals with relatively long limbs and small heads were predisposed to develop laterality and, consequently unevenness. CONCLUSIONS: Conformational traits may stimulate the development of laterality and therefore indirectly cause uneven feet.

Graves' ophthalmopathy: what is the evidence for extraocular muscle specific autoantibodies.

Graves' ophthalmopathy is thought to be an autoimmune disease. Whether this disease is organ specific or one of the manifestations of the closely linked Graves' thyroid disease is still a matter of speculation. Many papers describe autoimmunity to orbital antigens, in particular to extraocular muscles, in patients with Graves' ophthalmopathy. In this paper we have tried to give an overview of the evidence for circulating antibodies against extraocular muscle antigens and to discuss their significance in relation to the immunopathogenesis of the disease.