Balancing selection in Polish Arabian horses

Polish Arabian horses are a good example of a small population derived from a finite number of founders. Pedigree analysis showed significant reduction in the genetic diversity of the population. However, taking into account some circumstances suggesting the presence of balancing selection favouring heterozygotes in Polish breeding, it seems that this referred to pedigree uniformity rather than to a real decrease in genetic variability. The aim of the current study was to verify the hypothesis that balancing selection affects the population. The mare selection process was examined in detail regarding the polymorphism of 10 protein markers. The findings confirmed the tendency to favour the more heterozygous mares with regard to average heterozygosity in total and in relation to particular loci, studs, fathers and inbreeding ranges. The results were discussed in consideration of selection criteria, inbreeding level of Polish Arabs and heterozygosity in other populations.     

Glycosaminoglycans in horses with osteoarthritis

Horse articular cartilage glycosaminoglycans (GAGs) were measured in synovial fluids from 48 joints affected with osteoarthritis (OA), 22 normal joints, four joints with osteochondritis, three joints with traumatic arthritis and seven joints infected with bacteria. Serum and urine from individual horses were also examined for the presence of GAGs. High levels of GAGs were found in synovial fluids (SF) from horses with OA. In each case, the level was higher in the synovial fluid than in the serum or urine from the same horse. Horses with OA showed high GAG levels in SF, serum and urine compared to horses with normal and infected joints. High levels were also found in horses with osteochondritis and traumatic arthritis. Levels of synovial fluid GAG reflect cartilage destruction in arthritis and may be useful for monitoring disease progression in the equine species.     

Factor analysis of body measurements in Arabian horses

Data of 13 body measurements have been analysed from 166 Arabian horses, 123 mares and 43 stallions, ranging from 49 to 298 months of age, belonging to Alzahraa stud, Cairo, Egypt. General linear model was used to study age and gender effects on these measures. Gender was a significant source of variation for most studied traits, but not for neck girth, cannon bone circumference of fore and hind legs, and pastern girth of fore and hind legs. Age significantly affected pastern girths of fore and hind legs and cannon bone circumference of fore legs, while there was no significant effect on the other measurements. Pearson correlations, adjusted for age effect, between measurements were estimated and ranged from 0.02 to 0.84 for mares and from ?0.05 to 0.90 for stallions. Factor analysis with promax rotation for each gender was carried out to derive fewer independent common factors. Three factors were extracted which accounted for 66% and 67% of the total variance in mares and stallions respectively. The first, second and third factors in mares tended to describe body thickness, leg thickness and general size respectively; whereas in stallions they tended to differentiate among general size, leg thickness and body thickness respectively. The three extracted factors for each gender determine the main sources of shared variability that control body conformation in Arabian horses. These factors could be considered in selection programmes to acquire highly coordinated bodies in pure Arabian horses with fewer measurements.     

Communications and boundaries of the middle carpal and carpometacarpal joints in horses

To study communications and boundaries of the middle carpal and carpometacarpal joints of the horse, 50 forelimbs were obtained from fresh cadaver specimens. Blue latex solution (20 +/- 2.5 ml) was injected into the middle carpal joint, and the specimens were frozen in extension. Frozen specimens were cut into 1-cm sagittal sections from the middle of the radius to the middle of the metacarpus. The communications between the middle carpal and carpometacarpal joints and the presence, length, and position of the distopalmar outpouchings of the carpometacarpal joint were recorded. The middle carpal and carpometacarpal joints always communicated between os carpale III (C3) and os carpale IV (C4). An additional communication between the joints existed in 17 (34%) of the specimens, 10 on the palmar aspect of C4, and 3 on the palmar aspect of os carpale II (C2). When os carpale I (C1) was present (n = 5), communication between C1 and C2 was observed in 4 of the 5 specimens. In all specimens, medial and lateral distopalmar outpouchings of the carpometacarpal joint were observed and were located between the axial surface of os metacarpale II (MC2) and os metacarpale IV (MC4) and the abaxial surface of the suspensory ligament. There was no significant difference between the lengths of the lateral (2.3 +/- 0.54 cm) or medial (2.6 +/- 0.75 cm) distopalmar outpouchings. Small extensions from the distopalmar outpouchings were seen and extended axially into the fibers of the suspensory ligament or between the suspensory ligament and the distal accessory ligament of the deep digital flexor tendon.(ABSTRACT TRUNCATED AT 250 WORDS)     

Stabling is associated with airway inflammation in young Arabian horses

We examined the effect of stabling on upper and lower airway inflammation in 14 yearling Arabian horses that had been at pasture since birth. Horses were divided into 2 groups of 7. One group was stabled for 3 months and the other remained at pasture. The groups were then switched over for another 3 months. The nasopharynx, guttural pouches and trachea were examined endoscopically and bronchoalveolar lavage performed every month. An upper airway inflammation score was devised based on the magnitude of pharyngeal lymphoid hyperplasia and guttural pouch inflammation. During stabling this score remained constant, whereas it decreased during the 3 months at pasture. Stabling was also associated with a higher number and percentage of neutrophils in bronchoalveolar lavage fluid and with a smaller percentage of lymphocytes. There was no correlation between upper airway inflammation score and bronchoalveolar lavage cytology. During a nasal occlusion test, dorsal displacement of the soft palate occurred more times in stabled than in pastured horses, but this was heavily biased by the results from one animal. We conclude that stabling is associated with inflammation of both the upper and lower airway of young horses.     

Evaluation of a minimally invasive arthrodesis technique for the carpometacarpal joint in horses

Objective: To evaluate a minimally invasive technique for arthrodesis of the carpometacarpal (CMC) joint in horses. Study Design: Experimental study. Animals: Healthy horses (n=6). Methods: A 5.5 mm, 3‐drill tract arthrodesis technique was evaluated in 1 randomly selected CMC joint in each of 6 normal horses. Peak vertical ground reaction force (GRF) values were recorded before surgery and at 6, 8, and 12 months thereafter. Radiographic and clinical lameness scores were assigned at regular intervals until 12 months after surgery when the horses were euthanatized. Gross and histologic examinations were performed on the treated CMC joints. Results: After surgery, all horses were lame. Clinical resolution of lameness occurred in 2 by 12 months. Mean peak vertical GRF values significantly differed between treated and nontreated limbs at all recorded time points after surgery. Radiographic scores significantly differed from day 0 at all times after surgery, but did not change significantly after 4 months. Intraarticular bony ankylosis only occurred in 2 horses, based on gross, histologic, and microradiographic examination of sagittal sections of the operated CMC joints. Conclusion: The 5.5 mm, 3‐drill tract arthrodesis technique was considered successful in only 2 of 6 normal CMC joints treated. Greater articular damage may be necessary to achieve arthrodesis in normal horses. Better results may be achieved by technique modification or in horses affected by CMC osteoarthritis.     

Changes in blood biomarkers in Arabian horses with Clostridium difficile-induced enterocolitis

Clostridium difficile (CD) is considered a major health care problem both in developing and developed countries; frequently reported to be associated with enterocolitis and diarrhea in horses and other animals. In this study, we examined acute phase response (APR), cytokines response, neopterin (NP) procalcitonin (PCT) production and oxidative stress condition in horses and foals with C. difficile-induced enterocolitis (CDIE) and evaluated the effectiveness of these parameters as biomarkers for the disease. A total of 407 Arabian horses in 35 stables were examined between January 2017 to December 2018. Only 24 out of 407 horses showed two or more signs of CDIE. The blood level of serum amyloid A (SAA), haptoglobin (HP), proinflammatory cytokines (TNF-α, IL-6 and IL1-β), serum malondialdehyde (MDA), PCT and NPT in horses with CDIE were higher than in healthy horses. Nevertheless, the levels of nitric oxide (NO), superoxide dismutase (SOD) and total antioxidant concentration (TAC) were considerably lower in diseased horses compared to those that were healthy. The ROC curves for eleven selected blood parameters, both in healthy horses and horses with CDIE demonstrated that all examined blood markers had significant levels of differentiation between CDIE cases and healthy controls (AUC > 87.5). The data in this study suggest that the evaluation of acute-phase proteins, cytokines, PCT, NPT, and oxidative stress biomarkers may well be used as a tool for diagnosis and assessment of CDIE and in disease pathogenesis in Arabian horses.     

Measurement of phenol red thread tear test in Arabian and throughbred horses

Objective To determine physiologic levels of tear production in Arabian (AH) and throughbred horses (TH) by using phenol red thread test (PRT). Animals studied The study was performed on 16 AH and 14 TH, ranging from 2.5 to 24 years of age, housed in a stable situated in the Sanliurfa of Turkey. Procedures For the measurement of PRT, the strip was placed under the lower eyelid approximately one‐third the distance from the temporal to nasal canthus and left for 15 s. The length of the wet area was measured in mm and compared among breed, sex, and age groups and between eyes of both sides. Results The mean length of the wet area was in AH and TH were 30.22 ± 0.99 mm ranging from 16 to 41 and 31.00 ± 1.4 mm ranging from 14 to 47, respectively. There were no significant differences in tear production among breed, sex, or age groups. The values measured for left eyes were significantly higher than those for right eyes (P < 0.05). Conclusions Phenol red thread test measurement is easily used, with no pain, and a comfortable method. PRT can be used in equine ophthalmology on a routine basis to the measurement of tear production. These normal PRT values help diagnosis keratoconjunctivitis sicca in horses.     

Abnormal synaptic protein expression in two Arabian horses with equine degenerative myeloencephalopathy

Numerous swollen neurons and multiple dystrophic axons were observed in the gracillis and cuneatus nuclei of two male Arabian horses, aged six and 12 months of age, with equine degenerative myeloencephalopathy. Swollen neurons and dystrophic axons showed synaptophysin, synaptosomal-associated protein of 25 kDa, syntaxin-1 and alpha-synuclein immunoreactivity. Moreover, dystrophic axons were strongly immunopositive against the ubiquitin protein and against the anti-phosphorylated 200 kDa neurofilament protein. Abnormal expression of integral synaptic vesicle, synaptic vesicle-associated presynaptic plasma membrane and cytosolic proteins, which participate in the trafficking, docking and fusion of the synaptic vesicle to the plasma membrane, suggest that severe disruption of axonal transport plays a crucial role in the pathogenesis of dystrophic axons in equine degenerative myeloencephalopathy (EDM).     

The use of nutraceuticals for osteoarthritis in horses.

In horses, lameness is often attributable to some degree of osteoarthritis (OA), a complex disease process that is highlighted by eventual degradation of articular cartilage. Conventional therapies for OA in horses are designed to relieve pain and discomfort and often include pharmacologic intervention with nonsteroidal anti-inflammatory drugs or intra-articular steroids. Oral administration of nutraceutical products to the horse is common and easy and is perceived to be a benign treatment for OA in horses. The main goal for use of nutraceuticals is to use them in OA cases to attempt to lower the dose of other drugs that are more problematic while potentially preventing further degradation (disease or structure modifying). This article attempts to define a nutraceutical, identifies areas that need to be considered when these products are used, and describes the known scientific effects of the most common compounds contained in currently available equine nutraceuticals.     

Phenotypic and genetic parameter estimates for racing traits of Arabian horses in Turkey

The racing records for Arabian horses used in the study were obtained from the Turkish Jockey Club. The traits used in the study were racing time, best racing time, rank, annual earnings, earnings per start, log annual earnings and log earnings per start. Genetic parameters were estimated by the restricted maximum likelihood (REML) procedure using the DFREML program. The effects of age, sex and origin of horse were significant for each trait. The effect of year was significant on time and earning traits, but not rank. The effect of month on time traits was also significant. Heritability estimates of the entire data set were 0.280, 0.281, 0.069, 0.139, 0.174, 0.152 and 0.171 for racing time, best racing time, rank, annual earnings, earnings per start, log annual earnings and log earnings per start respectively. Estimates of repeatability varied from 0.349 to 0.500 for racing time, from 0.430 to 0.524 for best racing time and from 0.129 to 0.171 for rank depending on the data set used in the analyses. Best racing time was the most appropriate trait for selection in this study, as this might lead to genetic improvement than other traits.     

Severe combined immunodefiency disease (SCID) in the Arabian horse

Severe-Combined-Immunodeficiency-Disease (SCID) is discussed with special reference to its pathogenesis, clinical symptoms, pathology, and diagnosis. The disorder has been observed in the USA, Canada, Great Britain, and Australia and is characterized by an autosomal recessive mode of inheritance. The clinical features of the disease seen in Arab foals under 46 days of age are intermittent fever, (adenoviral) pneumonia, and weight loss sometimes associated with diarrhoea. From 1998 on, the SCID gene can be detected in the Netherlands by means of DNA analysis.     

Severe diaphragmatic necrosis in 4 horses with degenerative myopathy

Severe diaphragmatic necrosis occurred in horses with degenerative myopathy due to polysaccharide storage myopathy (n = 2), nutritional myopathy (n = 1), and vasculitis (n = 1). Blood gas analysis performed in 1 horse indicated development of respiratory acidosis. Respiratory muscle necrosis can be severe in horses with degenerative myopathy and can lead to respiratory failure.