Improving gait classification in horses by using inertial measurement unit (IMU) generated data and machine learning.

For centuries humans have been fascinated by the natural beauty of horses in motion and their different gaits. Gait classification (GC) is commonly performed through visual assessment and reliable, automated methods for real-time objective GC in horses are warranted. In this study, we used a full body network of wireless, high sampling-rate sensors combined with machine learning to fully automatically classify gait. Using data from 120 horses of four different domestic breeds, equipped with seven motion sensors, we included 7576 strides from eight different gaits. GC was trained using several machine-learning approaches, both from feature-extracted data and from raw sensor data. Our best GC model achieved 97% accuracy. Our technique facilitated accurate, GC that enables in-depth biomechanical studies and allows for highly accurate phenotyping of gait for genetic research and breeding. Our approach lends itself for potential use in other quadrupedal species without the need for developing gait/animal specific algorithms.

Effect of circadian rhythm, age, training and acute lameness on serum concentrations of cartilage oligomeric matrix protein (COMP) neo-epitope in horses.

BACKGROUND: Molecular serum markers that can identify early reversible osteoarthritis (OA) in horses are lacking. OBJECTIVES: We studied serum concentrations of a novel cartilage oligomeric matrix protein (COMP) neo-epitope in horses subjected to short-term exercise and with acute lameness. The effects of circadian rhythm and age were also evaluated. STUDY DESIGN: Longitudinal studies in healthy horses and cross-sectional comparison of lame and non-lame horses. METHODS: Sera were collected from five horses before and after short-term interval exercise and during full-day box rest. Sera from 32 acutely lame horses were used to evaluate age-related effects. Independent samples from control horses (n = 41) and horses with acute lameness (n = 71) were included. COMP neo-epitope concentrations were analysed using custom-developed inhibition ELISAs validated for equine serum. The presence of COMP neo-epitope was delineated in healthy and osteoarthritic articular cartilage with immunohistochemistry. RESULTS: COMP neo-epitope concentrations decreased after speed training but returned to baseline levels post-exercise. No correlations between age and serum COMP neo-epitope concentrations were found (r = 0.0013). The mean (±s.d.) serum concentration of COMP neo-epitope in independent samples from non-lame horses was 0.84 ± 0.38 µg/mL, and for lame horses was 5.24 ± 1.83 µg/mL (P<0.001). Antibodies against COMP neo-epitope did not stain normal articular cartilage, but intracytoplasmic staining was found in superficial chondrocytes of mild OA cartilage and in the extracellular matrix of moderately osteoarthritic cartilage. MAIN LIMITATIONS: ELISA was based on polyclonal antisera rather than a monoclonal antibody. There is a sex and breed bias within the groups of horses, also it could have been of value to include horses with septic arthritis and tendonitis and investigated joint differences. CONCLUSIONS: This COMP neo-epitope can be measured in sera, and results indicate that it could be a biomarker for pathologic fragmentation of cartilage in connection with acute joint lameness.

Is there a need for an emergency card in hypoparathyroidism?

BACKGROUND: Patients with hypoparathyroidism are at risk of both hypocalcemic and hypercalcemic crisis. Patients report that health professionals do not always respond adequately in an acute situation. The extent and handling of severe hypo- and hypercalcemia in hypoparathyroidism is unknown. AIMS: To outline the need for a medical emergency card for primary hypoparathyroidism. METHOD: Postal survey amongst Norwegian and Swedish patients with chronic hypoparathyroidism of all causes. Altogether 455 invitations were sent (333 from Norway and 122 from Sweden). RESULTS: Three hundred and thirty-six of 455 (74%) patients responded (253 from Norway and 83 from Sweden). The majority were women (79%), and the main cause was postsurgical hypoparathyroidism (66%). Overall 44% and 16% had been hospitalized at least once for hypo- or hypercalcemia, respectively. Eighty-seven per cent felt that an emergency card would be highly needed or useful. Amongst those hospitalized for hypocalcemia, 95% felt a card was needed compared to 90% amongst those hospitalized for hypercalcemia. Five per cent believed that a card would not be useful. CONCLUSIONS: The majority answered that an acute card is highly needed or useful. Hospitalization for acute hypocalcemia was more common (44%) than for acute hypercalcemia (16%). As a result of this survey, an emergency card will be distributed in three European countries to test its utility.

Detection of early osteoarthritis in the centrodistal joints of Icelandic horses: Evaluation of radiography and low-field magnetic resonance imaging.

REASONS FOR PERFORMING STUDY: Validated noninvasive detection methods for early osteoarthritis (OA) are required for OA prevention and early intervention treatment strategies. OBJECTIVES: To evaluate radiography and low-field magnetic resonance imaging (MRI) for the detection of early stage OA osteochondral lesions in equine centrodistal joints using microscopy as the reference standard. STUDY DESIGN: Prospective imaging of live horses and imaging and microscopy of cadaver tarsal joints. METHODS: Centrodistal (distal intertarsal) joints of 38 Icelandic research horses aged 27-29 months were radiographed. Horses were subjected to euthanasia approximately 2 months later and cadaver joints examined with low-field MRI. Osteochondral joint specimens were classified as negative or positive for OA using light microscopy histology or scanning electron microscopy. Radiographs and MRIs were evaluated for osteochondral lesions and results compared with microscopy. RESULTS: Forty-two joints were classified OA positive with microscopy. Associations were detected between microscopic OA and the radiography lesion categories; mineralisation front defect (P<0.0001), joint margin lesion (P<0.0001), central osteophyte (P = 0.03) and the low-field MRI lesion categories; mineralisation front defect (P = 0.01), joint margin lesion (P = 0.02) and articular cartilage lesion (P = 0.0003). The most frequent lesion category detected in microscopic OA positive joints was the mineralisation front defect in radiographs (28/42 OA positive joints, specificity 97%, sensitivity 67%). No significant differences were detected between the sensitivity and specificity of radiography and low-field MRI pooled lesion categories, but radiography was often superior when individual lesion categories were compared. CONCLUSIONS: Early stage centrodistal joint OA changes may be detected with radiography and low-field MRI. Detection of mineralisation front defects in radiographs may be a useful screening method for detection of early OA in centrodistal joints of young Icelandic horses.

Antibody and cellular immune responses of naïve mares to repeated vaccination with an inactivated equine herpesvirus vaccine.

Equine herpesvirus type 1 (EHV-1) continues to cause severe outbreaks of abortions or myeloencephalopathy in horses despite widely used vaccination. The aim of this work was to determine the effects of frequent vaccination with an inactivated EHV vaccine on immune development in horses. Fifteen EHV-1 naïve mares were vaccinated a total of 5 times over a period of 8 months with intervals of 20, 60, 90 and 60 days between vaccine administrations. Total antibody and antibody isotype responses were evaluated with a new sensitive EHV-1 Multiplex assay to glycoprotein C (gC) and gD for up to 14 months after initial vaccination. Antibodies peaked after the first two vaccine doses and then declined despite a third administration of the vaccine. The fourth vaccine dose was given at 6 months and the gC and gD antibody titers increased again. Mixed responses with increasing gC but decreasing gD antibody values were observed after the fifth vaccination at 8 months. IgG4/7 isotype responses mimicked the total Ig antibody production to vaccination most closely. Vaccination also induced short-lasting IgG1 antibodies to gC, but not to gD. EHV-1-specific cellular immunity induced by vaccination developed slower than antibodies, was dominated by IFN-γ producing T-helper 1 (Th1) cells, and was significantly increased compared to pre-vaccination values after administration of 3 vaccine doses. Decreased IFN-γ production and reduced Th1-cell induction were also observed after the second and fourth vaccination. Overall, repeated EHV vaccine administration did not always result in increasing immunity. The adverse effects on antibody and cellular immunity that were observed here when the EHV vaccine was given in short intervals might in part explain why EHV-1 outbreaks are observed worldwide despite widely used vaccination. The findings warrant further evaluation of immune responses to EHV vaccines to optimize vaccination protocols for different vaccines and horse groups at risk.

The effect of the 'Gait keeper' mutation in the DMRT3 gene on gaiting ability in Icelandic horses.

A nonsense mutation in DMRT3 ('Gait keeper' mutation) has a predominant effect on gaiting ability in horses, being permissive for the ability to perform lateral gaits and having a favourable effect on speed capacity in trot. The DMRT3 mutant allele (A) has been found in high frequency in gaited breeds and breeds bred for harness racing, while other horse breeds were homozygous for the wild-type allele (C). The aim of this study was to evaluate further the effect of the DMRT3 nonsense mutation on the gait quality and speed capacity in the multigaited Icelandic horse and demonstrate how the frequencies of the A- and C- alleles have changed in the Icelandic horse population in recent decades. It was confirmed that homozygosity for the DMRT3 nonsense mutation relates to the ability to pace. It further had a favourable effect on scores in breeding field tests for the lateral gait tölt, demonstrated by better beat quality, speed capacity and suppleness. Horses with the CA genotype had on the other hand significantly higher scores for walk, trot, canter and gallop, and they performed better beat and suspension in trot and gallop. These results indicate that the AA genotype reinforces the coordination of ipsilateral legs, with the subsequent negative effect on the synchronized movement of diagonal legs compared with the CA genotype. The frequency of the A-allele has increased in recent decades with a corresponding decrease in the frequency of the C-allele. The estimated frequency of the A-allele in the Icelandic horse population in 2012 was 0.94. Selective breeding for lateral gaits in the Icelandic horse population has apparently altered the frequency of DMRT3 genotypes with a predicted loss of the C-allele in relatively few years. The results have practical implications for breeding and training of Icelandic horses and other gaited horse breeds.

Mental health indicators and quality of life among individuals with musculoskeletal chronic pain: a nationwide study in Iceland.

OBJECTIVES: Musculoskeletal chronic pain is a costly public health threat. The aim of our study was to investigate mental health indicators, including self-reported symptoms of depression, sleep disruption, stress, well-being, and quality of life (QoL), among men and women with musculoskeletal chronic pain in a general population. METHOD: This was a cross-sectional study; a postal questionnaire was mailed to a stratified random sample of 9807 eligible Icelanders retrieved from a national registry, of whom 5906 responded (response rate = 60.2%). Chronic pain conditions included reports of current chronic back pain, chronic neck symptoms, and/or fibromyalgia. Gender-stratified associations of chronic pain conditions with mental health indicators were estimated with logistic regression analyses adjusting for age, income, body mass index (BMI), smoking, education, and residence. RESULTS: We observed higher odds of low satisfaction with life [adjusted odds ratio (OR(adj)) women 2.0, 95% confidence interval (CI) 1.5-2.6; OR(adj) men 2.3, 95% CI 1.7-3.1], higher levels of perceived stress (OR(adj) women 1.7, 95% CI 1.3-2.2; OR(adj) men = 1.5, 95% CI 1.1-2.1), depressive symptoms (OR(adj) women 2.4, 95% CI 1.9-3.0; OR(adj) men 2.8, 95% CI 2.1-3.7), and sleep disruption (OR(adj) women 2.8, 95% CI 2.2-3.5; OR(adj) men 2.2, 95% CI 1.5-3.1), and diminished QoL (OR(adj) women 1.6, 95% CI 1.2-2.1; OR(adj) men 1.5, 95% CI 1.0-2.1) among individuals with chronic pain compared with those without the condition. CONCLUSIONS: Our data indicate that individuals with musculoskeletal chronic pain have increased risk of poor mental health and diminished QoL. Further studies are needed on treatment and preventative measures of a decline in mental health among individuals with chronic pain.

Osteochondral lesions in distal tarsal joints of Icelandic horses reveal strong associations between hyaline and calcified cartilage abnormalities.

Osteochondral lesions in the joints of the distal tarsal region of young Icelandic horses provide a natural model for the early stages of osteoarthritis (OA) in low-motion joints. We describe and characterise mineralised and non-mineralised osteochondral lesions in left distal tarsal region joint specimens from twenty-two 30 ±1 month-old Icelandic horses. Combinations of confocal scanning light microscopy, backscattered electron scanning electron microscopy (including, importantly, iodine staining) and three-dimensional microcomputed tomography were used on specimens obtained with guidance from clinical imaging. Lesion-types were described and classified into groups according to morphological features. Their locations in the hyaline articular cartilage (HAC), articular calcified cartilage (ACC), subchondral bone (SCB) and the joint margin tissues were identified and their frequency in the joints recorded. Associations and correlations between lesion-types were investigated for centrodistal joints only. In centrodistal joints the lesion-types HAC chondrocyte loss, HAC fibrillation, HAC central chondrocyte clusters, ACC arrest and ACC advance had significant associations and strong correlations. These lesion-types had moderate to high frequency in centrodistal joints but low frequencies in tarsometatarsal and talocalcaneal-centroquartal joints. Joint margin lesion-types had no significant associations with other lesion-types in the centrodistal joints but high frequency in both the centrodistal and tarsometatarsal joints. The frequency of SCB lesion-types in all joints was low. Hypermineralised infill phase lesion-types were detected. Our results emphasise close associations between HAC and ACC lesions in equine centrodistal joints and the importance of ACC lesions in the development of OA in low-motion compression-loaded equine joints.

Functional limitations and physical symptoms of individuals with chronic pain.

OBJECTIVES: Chronic pain is a debilitating condition that may cause additional symptoms affecting the sufferers' working capacity and quality of life. Studying the prevalence and consequences of chronic pain in various populations remains important for a complete picture of the global burden imposed by chronic pain conditions. METHODS: We investigated the prevalence of self-reported chronic pain conditions in Iceland in addition to symptoms and functional limitations within the group, using a population-based random sample. A questionnaire was mailed to 9807 Icelanders aged 18-79 years and, of these, 5906 participated in the study. Chronic pain was considered manifest in people reporting chronic low back pain, chronic neck symptoms, and/or fibromyalgia. Prevalence calculations were weighted with respect to gender, age, and residential area to represent the underlying population. Associations of chronic pain conditions with symptoms and functional limitations were measured with adjusted logistic regression models, contrasting symptoms in individuals reporting any of the three pain conditions with those who did not. RESULTS: The population-estimated prevalence of chronic pain condition was 19.9% with distinct gender differences (men = 15.2%, women = 24.7%). Several symptoms and functional limitations in daily life were strongly associated with chronic pain, including deficient energy and muscular discomfort, physical mobility limitations, lifting groceries, climbing stairs, and stooping. Women, but not men, with chronic pain tended to refrain from physical activity. CONCLUSIONS: Chronic pain is a prevalent condition and those who report chronic pain generally suffer from ill health and limitations in their daily life compared to individuals not suffering from the condition.

Fourteen new microsatellite markers for Atlantic herring Clupea harengus.

Fourteen new microsatellite loci were developed and tested on Atlantic herring Clupea harengus with 39 individuals from Iceland and 49 individuals from Norway. The microsatellites, which contain di, tri and tetranucleotide repeats, are polymorphic (7-30 alleles), with observed heterozygosity ranging between 0·69 and 1·00 and expected heterozygosity between 0·55 and 0·97.

Risk of hip fracture in Addison's disease: a population-based cohort study.

OBJECTIVES: The results of studies of bone mineral density in Addison's disease (AD) are inconsistent. There are no published data on hip fracture risk in patients with AD. In this study, we compare hip fracture risk in adults with and without AD. DESIGN: A population-based cohort study. METHODS: Through the Swedish National Patient Register and the Total Population Register, we identified 3219 patients without prior hip fracture who were diagnosed with AD at the age of ≥30 years during the period 1964-2006 and 31 557 age- and sex-matched controls. Time to hip fracture was measured. RESULTS: We observed 221 hip fractures (6.9%) in patients with AD and 846 (2.7%) in the controls. Patients with AD had a higher risk of hip fracture [hazard ratio (HR) = 1.8; 95% confidence interval (CI), 1.6-2.1; P < 0.001]. This risk increase was independent of sex and age at or calendar period of diagnosis. Risk estimates did not change with adjustment for type 1 diabetes, autoimmune thyroid disease, rheumatoid arthritis or coeliac disease. Women diagnosed with AD ≤50 years old had the highest risk of hip fracture (HR = 2.7; 95 % CI, 1.6-4.5). We found a positive association between hip fracture and undiagnosed AD [odds ratio (OR) = 2.4; 95 % CI, 2.1-3.0] with the highest risk estimates in the last year before AD diagnosis (OR = 2.8; 95 % CI, 1.8-4.2). CONCLUSION: Both clinically undiagnosed and diagnosed AD was associated with hip fractures, with the highest relative risk seen in women diagnosed with AD ≤50 years of age.

Report of the 3rd Havemeyer workshop on allergic diseases of the Horse, Hólar, Iceland, June 2007.

Allergic diseases occur in most mammals, although some species such as humans, dogs and horses seem to be more prone to develop allergies than others. In horses, insect bite hypersensitivity (IBH), an allergic dermatitis caused by bites of midges, and recurrent airway obstruction (RAO), a hyperreactivity to stable born dust and allergens, are the two most prevalent allergic diseases. Allergic diseases involve the interaction of three major factors: (i) genetic constitution, (ii) exposure to allergens, and (iii) a dysregulation of the immune response determined by (i) and (ii). However, other environmental factors such as infectious diseases, contact with endotoxin and degree of infestation with endoparasites have been shown to influence the prevalence of allergic diseases in humans. How these factors may impact upon allergic disease in the horse is unknown at this time. The 3rd workshop on Allergic Diseases of the Horse, with major sponsorship from the Havemeyer Foundation, was held in Hólar, Iceland, in June 2007 and focussed on immunological and genetic aspects of IBH and RAO. This particular venue was chosen because of the prevalence of IBH in exported Icelandic horses. The incidence of IBH is significantly different between Icelandic horses born in Europe or North America and those born in Iceland and exported as adults. Although the genetic factors and allergens are the same, exported adult horses show a greater incidence of IBH. This suggests that environmental or epigenetic factors may contribute to this response. This report summarizes the present state of knowledge and summarizes important issues discussed at the workshop.

Establishment of a gene transfer system for Rhodothermus marinus.

Genetic manipulation of Rhodothermus marinus has been hampered by the lack of a selection system for gene transfer. We report construction of a Rhodothermus/Escherichia coli shuttle plasmid, containing the R. marinus trpB gene, based on pUC18 and the cryptic R. marinus plasmid pRM21. A plasmid-less R. marinus recipient strain was selected on the basis of growth characteristics and absence of restriction activity. The shuttle plasmid, pRM100, was successfully introduced into a TrpB- mutant of the recipient strain using electroporation and was found to transform it to prototrophy. No loss or rearrangement of pRM100 was observed after growth for 80 generations in non-selective medium. The relative copy numbers of pRM100 and of the parental plasmid, pRM21, were determined as 7+/-1 and 42+/-4, respectively. The shuttle plasmid was used to optimize an electroporation protocol, and the maximal number of transformants obtained was 4.3+/8-0.7x10(6) cfu/microg DNA at 22.5 kV/cm, 200 Omega and 25 microF. Transformation failed, however, after chemical preparation of cells according to several protocols. This is the first report of genetic transformation in the genus Rhodothermus.

High detail radiography and histology of the centrodistal tarsal joint of Icelandic horses age 6 months to 6 years.

REASONS FOR PERFORMING STUDY: Osteoarthrosis (OA) in the distal tarsal joints, bone spavin, is a well known condition which is common in Icelandic horses age 6-12 years. OBJECTIVES: To determine the nature, location and age of appearance of early radiographic and histological changes in the centrodistal tarsal joint (CD) of young Icelandic horses. METHODS: Slab sections from the CD of young Icelandic horses were examined by high detail radiography (age 6 months to 6 years, n = 111) and histology (age 6 months to 4 years, n = 82) to detect and describe the early changes indicative of OA. Horses younger than 5 years were unridden. RESULTS: Chondronecrotic lesions histologically similar to those described in the early pathogenesis of OA were seen in 33% of the joints, located both medially and laterally. Radiographic sclerosis of the subchondral bone was recorded in 60% of the specimens, most often medially. Medial location was not associated with chondronecrosis, but was strongly related to age. Sclerosis was an infrequent finding on the lateral side, and was probably secondary to chondronecrosis in the corresponding part of the joint. Small defects in the subchondral bone were considered to be the most specific radiographic sign of OA as they were strongly associated with chondronecrosis. CONCLUSIONS: The high prevalence of chondronecrosis in the young horses indicates an early onset and slow progression of the disease. The early appearance also shows that the initiation of the disease is unrelated to the use of horses for riding. As clinical manifestation of OA in the distal tarsal joints is most often described in mature or old horses, the first stages of the disease are not likely to result in clinical signs. Subchondral bone sclerosis did not appear to be a primary factor in the development of OA in the CD but was considered to reflect an uneven distribution of biomechanical forces within the joint. POTENTIAL RELEVANCE: The development of OA in the CD of young Icelandic horses seems to be due to poor conformation or joint architecture rather than trauma or overloading. These aetiological factors are likely to be of importance for OA in the distal tarsal joints in other breeds as well. The influence of hindlimb conformation and the architecture of the distal tarsal joints on the biomechanics of joints need to be investigated, preferably by locomotion analysis in young horses.

Posteroanterior motion test of a lumbar vertebra: accuracy of perception.

PURPOSE: The aim of this study was to investigate the accuracy of perception of forces applied to and displacement produced in an electromechanical one vertebral spinal model, among inexperienced and experienced physical, therapists performing posteroanterior pressure on a lumbar vertebra, before and after a training session. METHODS: Ten relatively inexperienced physical therapists and ten experienced manual therapists participated. An electromechanical single level spinal model was used for applying oscillatory posteroanterior pressure and measuring the forces on and displacement of the vertebra. A digital oscilloscope was used to give direct feedback to the therapists while performing mobilization to discern the magnitude of these two variables. RESULTS: The inexperienced group estimated the displacement accurately but the experienced group was significantly inaccurate (p<0.02), and both groups were inaccurate in estimating the force (p<0.001), before training. Following training, the inexperienced group maintained their accuracy on displacement and the experienced group improved their accuracy significantly (p<0.001). Both groups approached significance in improving their accuracy of force estimation. CONCLUSION: An electromechanical spinal model can be used as training tool along with an oscilloscope. Longer training may be needed for the force than the displacement for accurate perception.

Culling rate of Icelandic horses due to bone spavin.

A survival analysis was used to compare the culling rate of Icelandic horses due to the presence of radiographic and clinical signs of bone spavin. A follow-up study of 508 horses from a survey five years earlier was performed. In the original survey 46% of the horses had radiographic signs of bone spavin (RS) and/or lameness after flexion test of the tarsus. The horse owners were interviewed by telephone. The owners were asked if the horses were still used for riding and if not, they were regarded as culled. The owners were then asked when and why the horses were culled. During the 5 years, 98 horses had been culled, 151 had been withdrawn (sold or selected for breeding) and 259 were still used for riding. Hind limb lameness (HLL) was the most common reason for culling (n = 42). The rate of culling was low up to the age of II years, when it rose to 0.05 for horses with RS. The risk ratio for culling was twice as high for horses with RS compared with horses without RS and 5.5 times higher for culling because of HLL. The risk of culling (prognostic value) was highest for the combination of RS with lameness after flexion test, next highest for RS and lowest for lameness after flexion test as the only finding. It was concluded that bone spavin affects the duration of use of Icelandic horses and is the most common cause of culling due to disease of riding horses in the age range of 7-17 years.

Risk factors associated with hindlimb lameness and degenerative joint disease in the distal tarsus of Icelandic horses.

The aim of this study was to evaluate potential risk factors associated with hindlimb lameness and radiographic signs of degenerative joint disease (DJD) in the distal tarsus in Icelandic horses. The material consisted of riding horses (n = 420) age 6-12 years sired by 17 selected sires representing all major breeding lines, and of riding horses (n = 194) in the same age range sired by other sires. The examination protocol included the following: interview with owners/trainers, assessment of conformation, motion evaluation and radiographic examination. At the interview, data related to factors outside the horse (environmental variables) and data associated directly with the horse (intrinsic variables) were obtained. Data analysis was performed in 2 steps: screening using bivariate analysis, followed by testing with a multivariate logistic regression model. In the multivariate analysis, the factors of sire, age when broken to saddle and stud show participation were strongly associated with the prevalence of lameness. Height at the croup and ability to perform different gaits were also associated with the prevalence of lameness, but to a lesser degree. The risk factors of age, tarsal angle and birthplace were significantly associated with radiographic signs of DJD in the distal tarsus. Neither the variation in applied training intensity, the use of a professional or amateur trainer nor the temperament or front limb action of the individual horse was significantly associated with the prevalence of hindlimb lameness and/or radiographic signs of DJD in the distal tarsus in the Icelandic horse.

Detection of IgG and IgE serum antibodies to Culicoides salivary gland antigens in horses with insect dermal hypersensitivity (sweet itch).

We postulated that all horses exposed to the bites of Culcoides (midges) would have an antibody response to the antigen secreted in Culcoides saliva, but that IgE antibody would be restricted to allergic individuals. Using immunohistology on sections of fixed Culicoides, we have demonstrated the presence of antibodies in horse serum which recognise Culicoides salivary glands. Antibodies were detected in the serum of horses with insect dermal hypersensitivity and in the serum of normal horses exposed to Culicoides bites. In contrast, no antibodies were detected in serum from native Icelandic ponies which had not been exposed to Culicoides. Anti-salivary gland IgG antibodies were detected in serum from both allergic and healthy horses exposed to Culicoides. IgE antibodies were only detected in horses with signs of insect dermal hypersensitivity, they were not found in serum of healthy controls nor in the serum of horses with a history of hypersensitivity but in remission at the time of sampling. Using western blotting we confirmed the presence of antibodies to Culicoides antigens and demonstrated that individual horses react to different numbers of antigens. This paper demonstrates the ability of serum from allergic horses to detect Culcoides antigens and will enable further studies to isolate and characterise the allergens.

Radiographic and clinical survey of degenerative joint disease in the distal tarsal joints in Icelandic horses.

The prevalence of degenerative joint disease (DJD) in the distal tarsal joints and the relation between radiographic and clinical signs compatible with the disease were estimated in a population of Icelandic horses used for riding. The material consisted of 614 horses age 6-12 years (mean age = 7.9 years). Radiographs with 3 projections of each tarsus were made and a clinical examination, including palpation of the medial aspect of the distal tarsus and motion evaluation of the hindlimbs before and after a flexion test of the tarsus, was performed. Radiographic signs of DJD in the distal tarsal joints were found in 30.3% of the horses and the prevalence was strongly correlated with age. Hindlimb lameness before and after flexion test and palpation abnormalities were significantly associated with the radiographic findings. The lameness was usually mild and, in most cases, detectable only after the flexion test. The prevalence of lameness was not significantly correlated with age. Lameness could not be predicted by details of the radiographic findings.