Arabian Foals Research Articles

Cyanotic heart disease due to a hypoplastic right ventricle with pulmonary valve atresia, an intact ventricular septum, with atrial level shunting in a day‐old Arabian foal

AbstractAn 8‐h‐old Arabian foal was presented for evaluation of progressive weakness since birth. The foal presented laterally recumbent with pale and muddy mucous membranes, a grade III/VI left basilar murmur, and an irregularly, irregular rhythm. Transthoracic echocardiogram along with an electrocardiogram (EKG) was performed. Atrial fibrillation was recorded throughout the examination. The left and right atria were both significantly enlarged. A right to left shunt across the atrial septum was confirmed via an intravenous injection of agitated saline. The tricuspid valve was rudimentary without apparent atrioventricular flow and no ventricular septal defect was appreciated. The animal was euthanased, and necropsy found dysplasia of the tricuspid valve, a hypoplastic right ventricle with pulmonary valve atresia, and an intact ventricular septum. This condition is similar, both haemodynamically and in terms of prognosis, to tricuspid atresia, which has been described previously in Arabian foals, with the exception that there is the complete absence of connection between the atrium and ventricle in the case of tricuspid atresia. Of 14 previously reported cases of tricuspid atresia in neonatal foals, nine were Arabian foals. Further investigation into the possibility of hypoplastic right ventricle as a familial condition in the Arabian breed should be considered.

Meniscal disruption associated with septic arthritis in three neonatal foals

SummaryThe objective of this study was to report clinical characteristics, surgical management and medium‐term (6–12 months) outcomes of three Arabian neonatal foals with meniscal disruption associated with septic arthritis of the lateral femorotibial joint. The three neonatal Arabian foals with septic arthritis of the lateral femorotibial joint (LFTJ), were diagnosed with disruption of the lateral meniscal (LM). Suspicion of meniscal pathology was based on ultrasonography, computed tomography (in 2 foals) and confirmed during arthroscopy. Treatment included arthroscopic debridement and lavage of the joint with debridement of the meniscal disruption. Postoperative care included systemic and intra‐articular antimicrobials, based on culture and sensitivity results. Two of the foals received intra‐articular injections of autologous mesenchymal stem cells. Marked LM disruption was observed in the LFTJ of the affected joints of all foals, involving the meniscal body (n = 3) and caudal horn (n = 1). Purulent material within the torn tissue was debrided with a synovial resector. Foal 1 was lame‐free as a yearling. Foal 2 was lame at walk at 7.5 months and euthanised due to poor prognosis. Foal 3 showed mild lameness at trot in a straight line at 6 months. Disruption of the LM continued to be visible on US in both foals at these timepoints. It was concluded that meniscal disruption and infection should be considered as a differential in neonatal foals with persistent femorotibial septic arthritis. In such cases, the LM could be the primary nidus of infection.

Juvenile idiopathic epilepsy in Egyptian Arabian foals, a potential animal model of self-limited epilepsy in children.

Juvenile idiopathic epilepsy (JIE) is categorized as a generalized epilepsy. Epilepsy classification entails electrocortical characterization and localization of epileptic discharges (ED) using electroencephalography (EEG). Characterize epilepsy in Egyptian Arabian foals with JIE using EEG. Sixty-nine foals (JIE, 48; controls, 21). Retrospective study. Inclusion criteria consisted of Egyptian Arabian foals: (1) JIE group diagnosed based on witnessed or recorded seizures, and neurological and EEG findings, and (2) control group of healthy nonepileptic age-matched foals. Clinical data were obtained in 48 foals. Electroencephalography with photic stimulation was performed under standing sedation in 37 JIE foals and 21 controls. Abnormalities on EEG were found in 95% of epileptic foals (35 of 37) and in 3 of 21 control asymptomatic foals with affected siblings. Focal ED were detected predominantly in the central vertex with diffusion into the centroparietal or frontocentral regions (n = 35). Generalization of ED occurred in 14 JIE foals. Epileptic discharges commonly were seen during wakefulness (n = 27/37 JIE foals) and sedated sleep (n = 35/37 JIE foals; 3/21 controls). Photic stimulation triggered focal central ED in 15 of 21 JIE foals. Juvenile idiopathic epilepsy has a focal onset of ED at the central vertex with spread resulting in clinical generalized tonic-clonic seizures with facial motor activity and loss of consciousness. Electroencephalography with photic stimulation contributes to accurate phenotyping of epilepsy. Foals with this benign self-limiting disorder might serve as a naturally occurring animal model for self-limited epilepsy in children.

A case-control study of atypical guttural pouch empyema in Arabian foals.

Upper respiratory disease was reported over many seasons in Arabian foals on a single stud farm in the Middle East. Affected foals were noted to have mucopurulent nasal discharge, cough, fever and tachypnea. All affected foals had been empirically treated with a macrolide and rifampicin, by the referring veterinarian without improvement. On endoscopic examination, all affected foals had significant guttural pouch empyema (GPE). (1) To document a previously unreported presentation of guttural pouch empyema (GPE) in a family of juvenile Arabian foals; (2) To document the cytological and microbial composition of the empyema; (3) To identify clinical signs significantly correlated with the presence of GPE, as predictors for the need for guttural pouch (GP) endoscopy; (4) To demonstrate successful resolution of the identified syndrome with mechanical GP lavage and evidence based antimicrobial use, improving antibiotic stewardship and the one-health approach to respiratory disease in this demographic of foals. Evaluation and scoring of clinical signs, upper airway endoscopy and thoracic ultrasound were performed in 14 affected foals and 10 age-matched controls, followed by comparative tracheal and guttural pouch sputum culture and cytological evaluation. Therapeutic GP lavage was performed and response to therapy monitored. GPE, cranioventrally distributed ultrasonographic lesions and opportunistic pathogen infection suggested a primary lesion of GPE with aspiration of GP discharge into the lungs. GP lavage resolved the empyema and associated clinical signs in all cases. Cytological examination of tracheal and guttural pouch aspirates revealed a neutrophilic exudate with lipid-laden phagocytes, suggestive of engulfed milk. Bacteriology revealed a high prevalence of Streptococcus equi ssp. zooepidemicus admixed with other opportunistic pathogens. Streptococcus equi ssp. equi was not isolated in any case.

Juvenile Idiopathic Epilepsy in Arabian Horses is not a Single Gene Disorder.

Valued for their temperament, beauty, athletic ability, and exhibition in the show ring, Arabian horses are an important component of the horse industry. Juvenile Idiopathic Epilepsy (JIE), a seizure disorder, is most often reported in Arabian foals from birth to six months of age. Affected foals exhibit tonic-clonic seizures lasting as long as five minutes and risking secondary complications like temporary blindness and disorientation. Some foals outgrow this condition, while others die or suffer lifelong complications if not treated. Previous work suggested a strong genetic component to JIE and proposed JIE to be a single-gene trait. In this work we conducted a GWAS in 60 cases of JIE and 120 genetically matched controls, identifying loci suggesting JIE is not caused by a single locus. Coat color (chestnut, grey) phenotypes were used as positive control traits to assess the efficacy of GWAs in this population. Future work will attempt to future define candidate regions and explore a polygenic mode of inheritance.

SURVEY OF SCID GENE AND IMMUNOLOGICAL STATUS IN ARABIAN MARES AND FOALS

Horses have been shown to have the deadly genetic condition calledsevere combined immunodeficiency (SCID). Animals with the condition are unable to produce specific antigens for immunological responses as a result, they become extremely vulnerable to pathogenic pathogens and die before six months.The control and responses to pathogens of neonatal and young foals immune responses differ from those of adults. The purpose of this study to determine carrier of SCID gene in Arabian foals and mares in addition assessing cellular and humoral immunity in Arabian foals and mares. Thirty-eight, Arabian foals and mares were examined.Hair samples were examined for detection of SCID gene by fragment analysis. While blood samples were collected for erythrogram and leukogram. Also, immunoglobulins including Ig E, Ig G, Ig A and Ig M. Also, SAA and fibrinogen were measured in serum and genes expression using Real Time-PCR were performed for IL-10, IL-6, TNFα and TLR 4 mRNA. All samples were homozygous and free from SCID gene. RBCS and monocytes showed significantly high value in foals compared to mares while, there were significant high value in MCV, IgG, IgM, IL-10, IL-6, TNF-α, TLR 4 mRNA expression in mares compared to foals. SAA and Fibrinogen showed non-significant difference in mares and foals.SCID diagnostic tests will aid in breeding programme selection to prevent carrier-to-carrier mating. Also assessing immunity in mares and foals is very important tools to determine the optimal immunological pathways and provide fresh preventative measures to ward off contagious diseases.

Electroencephalographic evaluation under standing sedation using sublingual detomidine hydrochloride in Egyptian Arabian foals for investigation of epilepsy.

A standardized protocol for electroencephalography (EEG) under standing sedation for the investigation of epilepsy in foals is needed. To evaluate a modified standardized EEG protocol under standing sedation using sublingual detomidine hydrochloride in Egyptian Arabian foals. Nineteen foals (controls, 9; juvenile idiopathic epilepsy [JIE], 10). Descriptive clinical study. Foals were classified as controls or epileptic based on history or witnessed seizures and neurological examination. Foals were sedated using sublingual detomidine hydrochloride at a dosage of 0.08 mg/kg to avoid stress associated with injectable sedation. Once foals appeared sedated with their heads low to the ground and with wide base stance (30 minutes), topical lidocaine hydrochloride was applied at the determined locations of EEG electrodes. Fifteen minutes were allowed for absorption and electrodes were placed, protected, and EEG recording performed. Level of sedation was considered excellent with no need of redosing. The EEG recording lasted from 27 to 51 minutes and provided interpretable data. Epileptic discharges (ED) were noted predominantly in the central-parietal region in 9 of 10 epileptic foals. Photic stimulation triggered ED in 7 of 10 epileptic foals and in none of the controls. Foals were not oversedated and recovered uneventfully. Sublingual detomidine hydrochloride is a safe, painless, simple, and effective method of sedation for EEG recording in foals. Sublingual sedation allowed the investigation of cerebral electrical activity during states of sleep and arousal, and during photic stimulation for the investigation of epilepsy in foals.

EFFECTOF EHV VACCINE ON IMMUNOLOGICAL PARAMETERS IN ARABIAN FOALS

By mimicking the infections, vaccines can offer protection from some diseases. This sort of imitating infections helps to teach the immune system how to combat an infection in the future.Discovery of immune responses linked to vaccination protection in Arabian horses has been a long-standing objective for scientists.The purpose of this study was to investigate the changes of immunological parameters before and after vaccination by Fluvac Innovator® vaccine in Arabian foals. Twenty healthy, Arabian foals of both sexes were examined (before vaccination and after vaccination) 20 blood samples were examined before vaccination and 20 blood samples were examined at 45 days of vaccination. Leukogramwas performed. Immunoglobulins including Ig E, Ig G, Ig A and Ig M were measured in serum and genes expression using Real Time-PCR were performed for IL-10, IL-6, TNFα and TLR 4 mRNA.After vaccination, there were significant increases in lymphocytes, IgG, IgM, IL-10, IL-6, TNF-α, TLR 4 mRNA expression in males and females when compared to basal value before vaccination. therefore, assessing humoral response (immunoglobins A, M, G and E) and cellular response (WBCs, IL-10, IL-6, TNF- α and TLR-4) is an important tool for determination Fluvac Innovator® vaccine effect on immunity.

Evaluation of serum concentration of acute-phase proteins (haptoglobin and serum amyloid A) in the affected Arabian foals with rhodococcosis.

Early detection of Rhodococcus equi pneumonia in foals is essential for horse health and for veterinarians. This study aimed to demonstrate the usefulness of assessing the serum concentration of acute-phase proteins (APPs) in the early diagnosis of pneumonia. The study evaluated APPs in 19 Arabian foals with R. equi pneumonia and compared them with 18 normal Arabian foals in equestrian clubs in Tabriz, Iran. Affected foals were identified through history, clinical findings and bacterial culture of tracheal washing. Biochemical methods and polymerase chain reaction tests were performed by examining the 16S rRNA and vapA genes to confirm the diagnosis of bacterial isolates. Blood samples were taken from all sick and healthy horses, and their serum was isolated. APPs in the serum were measured in all the samples. Rhodococcosis increased the serum concentration of haptoglobin (Hp) and serum amyloid A (SAA) (p < 0.001). The relationship between SAA and Hp was meaningful in the infected group (r = 0.933) but not in the healthy group. In cases where there are clinical findings of R. equi pneumonia, the concentration of SAA and Hp can help the effectiveness of treatment. Serum concentration analysis of APPs can be helpful in early diagnosis and successfully treating foals with R. equi pneumonia.

Changes in serum total protein and immunoglobulin G concentrations and Brix percentages in neonatal Arabian foals from birth up to 21 days of age

The aim of this study was to evaluate changes in the serum immunoglobulin G (IgG) and serum total protein (STP) concentrations and serum Brix percentages of neonatal Arabian foals during first 3 weeks of life. Blood samples were collected from 12 apparently healthy foals by jugular venipuncture at birth and at 12-hours, 24-hours, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15 and 21 days of age. Serum IgG and STP concentrations and Brix percentages were measured by the radial immunodiffusion assay, and digital STP and Brix refractometers, respectively. Based on the serum IgG concentrations measured at 24 h, two foals were diagnosed with failure of transfer of passive immunity (FTPI). While IgG concentrations were determined using the data of foals with adequate transfer of passive immunity, other calculations were made using the data of all foals. The mean IgG concentration of the foals increased from birth (<200 mg/dl) to 12 (2068.5 mg/dl) and 24 h (2184.7 mg/dl), and progressively decreased up to 21 days of age (1318.5 mg/dl). The serum IgG concentrations at 12 h were highly correlated with each of the IgG concentrations measured over the 21-day period. The serum IgG and STP concentrations and Brix percentages of the foals diagnosed with FTPI at 12 h did not reach the adequate strata over time. These results suggest that foals can be reliably tested for passive immunity status at 12 h after birth.

Evaluation of refractometry methods for estimating passive immunity status in neonatal foals

The objective of this cross-sectional study was to determine the accuracy of the digital Brix and serum total protein (TP) refractometers for estimating different passive immunity status in neonatal foals. In total, 18- to 40-h old purebred Arabian foals (n=185) were used. Serum TP concentrations, total solid percentages and IgG concentrations were measured with a digital serum TP refractometer, digital Brix refractometer and the gold standard radial immunodiffusion (RID) assay, respectively. Correlation coefficients were calculated between the refractometer and RID assay results. A receiver operating characteristic analysis was used to select the optimal cut-offs for both refractometers. Test performance and agreement were evaluated using diagnostic test characteristics at optimal thresholds and areas under the ROC curve, and by calculating Cohen's kappa coefficient. The sensitivity and specificity of the digital Brix refractometer at optimal cut-offs (≤7.8%, ≤7.9%, ≤8.2%, ≤8.3%, ≤9.0%) were 100 and 69.3%; 100% and 68.5%; 70.5% and 71.0%; 88.3% and 85.5%; 88.1% and 76% to estimate RID-IgG of <400mg/dL, <800mg/dL, <1500mg/dL, <2500mg/dL and<3000mg/dL, respectively. The sensitivity and specificity of the digital serum TP refractometer at optimal cut-off (≤4.6g/dL, ≤4.6g/dL, ≤4.8g/dL, ≤5.0g/dL, ≤5.4g/dL) were 100 and 69.3%; 100% and 72.8%; 90% and 72.8%; 72.9% and 83.9%; 84.4% and 88% to estimate RID-IgG of <400mg/dL, <800mg/dL, <1500mg/dL, <2500mg/dL and<3000mg/dL, respectively. In conclusion, the refractometers showed a good potential as screening tools for the estimation of different IgG concentrations in neonatal foals.

Acquired large colon strangulating inguinal herniation in two Arabian foals

SummaryLarge colon inguinal hernias are rare, and successful outcome reports are lacking. The present case report describes the clinical presentation, surgical treatment and outcome of two Arabian foals, presented to the hospital at several weeks of age, with colic signs due to inguinal herniation of the large colon. Case 1 describes a right indirect inguinal hernia and Case 2 describes a left direct inguinal hernia, both involving the pelvic flexure. In both cases, the colts underwent surgical treatment while preserving the ipsilateral testis, recovered well and had good long‐term outcomes.

Evidence for origin of lavender foal syndrome among Egyptian Arabian horses in Egypt.

Lavender foal syndrome (LFS) is a fatal hereditary condition that is inherited in an autosomal recessive pattern. This detrimental mutation is more common in Arabian foals of Egyptian origin than foals from other bloodlines. Heterozygous horses are carriers of the LFS trait and appear normal, while recessive homozygous foals died shortly after birth due to serious complications. In Egypt, in 2014, an Egyptian foal died after manifestations of neurological signs and abnormal coat colour as LFS signs. Therefore, it is important to identify LFS carriers in the population of Arabian horses in Egypt and to encourage improvement of the Arabian horse industry in Egypt by constructing a breeding system based on genetic background in order to avoid mating between carriers and reduce financial losses from deaths of affected foals. To establish a PCR-based test for detecting the MYO5A gene mutation causing LFS in the registered Arabian horse population in Egypt prior to breeding. Cross sectional survey (n= 170) plus targeted sampling (n= 30). A total of 200 samples were collected from an Arabian farm in Egypt and some of them were traced for LFS based on the farm records. The LFS genotypes were identified using the PCR-RFLP technique, fragment analysis followed by sequence analysis. The overall mutated allele and genotype frequencies (N/L) were 0.08 and 16%, respectively. The observed frequency of heterozygotes suggests foals affected with LFS will be produced among Arabian horses in Egypt. Therefore, screening of the entire population for this mutation should be undertaken in the breeding program.

Safkan Arap Taylarında Gelişimsel Ortopedik Hastalıkların ve Kemik Lezyonlarının Klinik ve Radyografik Tanısı

The main objective of the present study was to determine the presence and prevalence of developmental orthopedic diseases and bone lesions, which causes huge economical looses in the purchasing of foals, in Thoroughbred Arabian foals in Tigem Anatolian Farm. The materials for this study were 50 Thoroughbred Arabian foals which were born on the same season. In total 50 foals were evaluated for clinical and radiographic examinations, blood analysis and nutrition for 12 months from birth. In addition, pasture soil and water analyzes were viewed. Variety of bone lesions were observed in 25 of 50 foals that are involved in the study. In foals hindlimb and/or forelimb sesamoiditis, osteochondrosis dissecans, physitis, subchondral cystic lesions were observed alone or together. We concluded that the clinical examination is inadequate and radiographic examinations are necessary for definitive diagnosis of developmental orthopedic diseases and bone lesions that are affecting horses’ future race performance. This study also shows that the blood parameters change during foal’s physical development, but these changes don’t affect developmental orthopedic diseases.

Clinical and radiographic diagnosis of developmental orthopedic disease and bone lesions determined in thoroughbred arabian foals in Turkey

Clinical and radiographic diagnosis of developmental orthopedic disease and bone lesions determined in thoroughbred arabian foals in Turkey

Study on β-haemolyticstreptococci infection inEquines at different seasons and ages

The present work was undertaken to study the incidence of β-haemolytic streptococci infection in equine. On clinical examination of a community of 524 Arabian foals and horses in Cairo – Egypt, a total of 164 animals were selected showing respiratory signs (31.30 %) of which 62 (11.83 %) showed respiratory signs and lymph nodes abscessation. Two hundred and twenty six swabs,164 nasal,31submaxillary lymph node pus and 31 retropharyngeal lymph node pus, were collected from 164 foals and horses showing respiratory signs and/ or abscessed lymph nodes for Streptococci isolation and PCR confirmation. A total of 150 isolates of Streptococci were recovered from 226 samples with sample-wise prevalence of (66.37%). Out of these 150 isolates, 124(28.67%) were identified as Streptococcus equisubsp. equi, 26(17.33%) as S. equisubsp.zooepidemicus and no S. dysgalactiae subsp. Equisimilis were identified. The incidence of S. equisubsp.Equi and S. equisubsp.Zooepidemicus infection among the total animal population, in the present study, was 11.83 and 4.96 % respectively. PCR technique showed high sensitivity and specificity for the detection of S. equi species in the examined samples.

Occurrence, hematologic and serum biochemical characteristics of neonatal isoerythrolysis in Arabian horses of Iran

Neonatal isoerythrolysis is a major cause of anemia in newborn foals. However, there are no documented data regarding the occurrence of neonatal isoerythrolysis in Arabian horses of Iran, which are mostly raised in Khouzestan province. Hence, this study was carried out to investigate the occurrence of neonatal isoerythrolysis in Arabian horses of Khouzestan and assess the hematologic and serum biochemical profile of affected foals. A total of 20 neonatal foals, under one week of age, and their dams were involved in this study. Clinical examinations revealed no abnormality except in one foal with icteric mucous membranes, lethargy, tachycardia, tachypnea, hypothermia and hemoglobinuria which led to death. The diagnosis of neonatal isoerythrolysis was made based on erythrocyte agglutination in cross-match test between the mare serum and foal erythrocytes with the titer of 1:128, while other studied cases were assumed negative according to the test results. In the laboratory assessment, the foal with hemolytic anemia showed a major decline in hematocrit, hemoglobin concentration and erythrocyte count along with considerable leukocytosis and neutrophilia. Serum total and direct bilirubin concentrations in the NI case was about ten times higher than in the rest of the foals. This study revealed that neonatal isoerythrolysis can occur in Arabian foals of Khouzestan and is associated with severe anemia and icterus which may lead to death. These findings can be beneficial in the establishment of preventive measures in Arabian horse breeding industry in the region, as well as improving therapeutic methods.

Prevalence and sequence analysis of equid herpesviruses from the respiratory tract of Polish horses

BackgroundEquid herpesviruses (EHVs) are widespread in equine populations worldwide. While the infection with equine α-herpesviruses (EHV-1 and EHV-4) has been linked to several clinical outcomes, the pathogenic potential for equine γ-herpesviruses (EHV-2 and EHV-5) is still unclear. The objective of the current study was to determine the prevalence of infection with EHVs among Polish horses, to investigate factors associated with EHV infections among horses sampled, and to determine genetic variability within Polish EHV-2 isolates.MethodsVirus-specific real-time PCR assays were used for detection of EHV-1, EHV-2, EHV-4 and EHV-5 in nasal swabs collected from 540 horses from 13 national horse studs located throughout Poland. A proportion of EHV-2/5 positive samples were subjected to virus isolation followed by amplification and analysis of partial glycoprotein B sequence.ResultsOverall, 448/540 (83.0%) horses sampled were positive for at least one virus. The most prevalent was infection with EHV-2 (77.2%), followed by EHV-5 (47.0%), and EHV-4 (0.4%). None of the horses was positive for EHV-1. Approximately half of the virus-infected horses were positive for both EHV-2 and EHV-5. The proportion of EHV-2/5 positive horses varied by age, breed, and season. Only 8.0% of horses sampled, mostly Arabians, showed clinical signs of respiratory disease at the time of sampling. The viral load of both EHV-2 and EHV-5 DNA was highest in swabs from young horses, which was particularly evident for EHV-2 infected foals. Mean viral loads in nasal swabs collected from diseased horses were higher than in swabs from healthy horses. That was also true for EHV-2 when only diseased Arabian foals were considered, but the levels of EHV-5 DNA were lower in swabs from diseased than from healthy foals. In agreement with other studies, there was a considerable variability between Polish EHV-2 sequences, with no clustering of sequences from horses with different health status. The level of EHV-2 variability seemed to differ between different studs/breeds.ConclusionsThe presence of foals and yearlings on a property is likely to increase the risk of active EHV-2/5 infection among in-contact horses. The existence of breed-specific differences in susceptibility to EHV-2/5 infections should be further investigated, as it may provide one variable that needs to be considered in attempts to associate EHV-2/5 infections with disease. Overall, the data presented add to the existing knowledge of the epidemiology and biology of equine γ-herpesviruses, with the long-term goal of better understanding of the pathogenesis and the impact of infections with these viruses on the well-being of the horse.

Investigation of Known Genetic Mutations of Arabian Horses in Egyptian Arabian Foals with Juvenile Idiopathic Epilepsy.

BackgroundThe carrier status of lavender foal syndrome (LFS), cerebellar abiotrophy (CA), severe combined immunodeficiency (SCID), and occipitoatlantoaxial malformation (OAAM1) in foals with juvenile idiopathic epilepsy (JIE) is unknown.Hypothesis/ObjectivesTo determine the carrier status of LFS, CA, SCID, and OAAM1 in foals with JIE.AnimalsTen foals with JIE.Materials and MethodsArchived DNA samples were tested for known genetic mutations causing LFS, CA, SCID, and OAAM1. The inclusion criteria consisted of having been diagnosed with JIE by ruling out other causes of seizures in foals and supported by electroencephalographic examination.ResultsTen Egyptian Arabian horses (5 females and 5 males) were phenotyped as foals with JIE by electroencephalography (EEG). All foals were negative for the genetic mutations that cause LFS, CA, SCID, and OAAM1 except for 1 foal that was a carrier of CA.Conclusions and Clinical ImportanceJuvenile idiopathic epilepsy of Egyptian Arabian foals and LFS appear to be phenotypically and genetically distinct disorders. There was no apparent association between JIE and LFS, CA, SCID, and OAAM1.

A comparative study of oculomotor, trochlear and abducens nerves in Arabian foals

We investigated the microscopic structure of transverse sections of the oculomotor, trochlear and abducens nerves of Arabian foals using stereological methods. Bilateral nerve pairs from 2-month-old female Arabian foals were analyzed. The tissues were embedded in plastic blocks, then 1 µm thick sections were cut and stained with osmium tetroxide and methylene blue-azure II. Stereology was performed using light microscopy. Morphometry showed that the right and left pairs of nerves were similar. The transverse sectional areas of the oculomotor, trochlear and abducens nerves were 1.93 ± 0.19 mm2, 0.32 ± 0.06 mm2 and 0.70 ± 0.08 mm2, respectively. The oculomotor nerve exhibited a significantly greater number of myelinated axons (16755 ± 1279) and trochlear (2656 ± 494) and the abducens nerves (4468 ± 447). The ratio of the axon diameter to myelinated nerve fiber diameter was 0.58, 0.55 and 0.55 for the oculomotor, trochlear and abducens nerves, respectively. Of the three nerves studied, the abducens nerve exhibited the greatest nerve fiber area, myelin area, nerve and axon diameters, and myelin thickness. The ratio of small myelinated nerve fibers was greatest in the oculomotor nerve.