Mixed Inheritance of Equine Recurrent Airway Obstruction

Background: Mode of inheritance of equine recurrent airway obstruction (RAO) is unknown.
Hypothesis: Major genes are responsible for RAO.
Animals: Direct offspring of 2 RAO-affected Warmblood stallions (n = 197; n = 163) and a representative sample of Swiss Warmbloods (n = 401).
Methods: One environmental and 4 genetic models (general, mixed inheritance, major gene, and polygene) were tested for Horse Owner Assessed Respiratory Signs Index (1–4, unaffected to severely affected) by segregation analyses of the 2 half-sib sire families, both combined and separately, using prevalences estimated in a representative sample.
Results: In all data sets the mixed inheritance model was most likely to explain the pattern of inheritance. In all 3 datasets the mixed inheritance model did not differ significantly from the general model ( P = .62, P = 1.00, and P = .27) but was always better than the major gene model ( P < .01) and the polygene model ( P < .01). The frequency of the deleterious allele differed considerably between the 2 sire families ( P = .23 and P = .06). In both sire families the displacement was large ( t = 17.52 and t = 12.24) and the heritability extremely large ( h ²= 1).
Conclusions and Clinical Relevance: Segregation analyses clearly reveal the presence of a major gene playing a role in RAO. In 1 family, the mode of inheritance was autosomal dominant, whereas in the other family it was autosomal recessive. Although the expression of RAO is influenced by exposure to hay, these findings suggest a strong, complex genetic background for RAO.     

A Comparison Between Polymerase Chain Reaction and Enzyme-Linked Immunosorbent Assay Methods for Detecting Leptospira in Equine Recurrent Uveitis

Leptospirosis is a widespread zoonotic disease that affects humans and many species of animals. Leptospiral organisms have long been presumed to be associated with the presence of equine recurrent uveitis (ERU). The connection between ERU and leptospirosis can be established using various techniques. In the current study, we used a polymerase chain reaction (PCR) assay to help establish a diagnosis of ERU caused by Leptospira infection and compared the results with those of enzyme-linked immune assay (ELISA). A total of 31 and 30 serum samples were taken from horses with ERU (based on clinical diagnosis) and horses that were healthy, respectively, between June 2007 and December 2008. The results showed that from 31 affected horses, a total of seven and five samples were positive for leptospiral infection using PCR and ELISA, respectively, whereas there was no evidence of infection with Leptospira spp. in 30 serum samples of healthy horses. All of the positive samples in ELISA were also positive by PCR, whereas PCR detected two positive cases that were negative by ELISA. Although there was no significant difference between these two methods, it is apparent that PCR may be a more reliable tool for detecting the presence of leptospires in ERU.     

A Comparative Review of Vitamin E and Associated Equine Disorders

Vitamin E is a primary chain‐breaking antioxidant that prevents cyclic propagation of lipid peroxidation. Across species, vitamin E is essential for normal neuromuscular function by acting as a potent antioxidant, as well as by modulating the expression of certain genes, inhibiting platelet aggregation and stabilizing plasma membranes. This review focuses on vitamin E structure, absorption, metabolism, current equine dietary recommendations, the interplay between antioxidants and exercise, a discussion of the necessity of vitamin E supplementation in the horse above the Nutritional Research Council (NRC) 2007 requirements, and a review of equine diseases that are associated with a vitamin E deficiency. Particular emphasis is placed on the proteins involved in vitamin E absorption, transport, and metabolism as potential candidates for vitamin E‐associated diseases across species.     

A Review of Equine Grazing Research Methodologies

Recently, there has been a renewed interest and an increase in published research on equine grazing and pasture management. The objectives of this paper are to review equine grazing research methodologies with an aim to encourage standardized research procedures. This review highlights standard methods used in equine pasture-related research, including use of climate data and soil type; seed bed preparation and grazing management; determining forage nutritive value; defining forage maturity; tracking horse health parameters; evaluating different grazing systems; and future technologies. This review covers in-depth discussions on determining forage biomass yield, forage populations, ground cover, persistence, forage intake, and grazing behavior. Specifically, mechanical harvesting, hand clipping, rising plate meter, and falling plate meter are all methods used to determine forage biomass yield. Frequency grid, point sampling, visual assessment, Natural Resources Conservation Service pasture condition score, and the double Dominant, Abundant, Frequent, Occasional, Rare (DAFOR) scale can be used to track forage populations, ground cover, and persistence of pasture species. Three primary methods have been used when estimating horse forage intake including the difference between pre- and postgrazing herbage mass, the difference in pre- and postgrazing bodyweight, and use of digestibility and fecal output markers. Equine grazing behavior has been described by investigating preference, pre- and post-sward height, and bite and mastication rate. Awareness of key methodologies should encourage movement toward research protocol standardization that will allow for scientific comparisons and application of pasture-related research results across the horse industry.     

A Quantitative Review of the Equinalysis System for Equine Locomotion Analysis

Movement analysis techniques allow objective and quantitative assessment of kinematic gait analysis. Consistent repeatability of the kinematic data is essential for such assessments. This study investigated whether the repeatability of a standardized Equinalysis Elite gait analysis system is sufficient to allow its use in clinical evaluation of equine lameness with reliable documentation of individual locomotion patterns. The extent to which examinations on different days affected the results when a standardized protocol was used was investigated. The repeatability of distal limb kinematics in nine sound horses over three successive days at one location was investigated. Measurements were performed at the examination area, for three motion cycles at the walk and trot, in each direction per day. Skin markers were placed on the lateral aspect of the coffin joint, forelimb fetlock joint, hindlimb fetlock joint, carpus, tarsus, elbow, and stifle, at clipped sites marked with a permanent marker. The inter-day repeatability of angular measurements of the carpus, tarsus, forelimb fetlock, and hindlimb fetlock joints was determined. A low degree of inter-day repeatability was found with statistically significant (P ≤ .05) differences between findings on different days, observed in the time-angle diagrams of left and right carpus, tarsus, forelimb fetlock, and hindlimb fetlock joints of all horses, at both walk and trot. The standardized Equinalysis Elite system for gait analysis of distal limb kinematics in the horse did not provide highly repeatable data in this setting.     

Success of Anterior Chamber Paracentesis as a Treatment for Ocular Setariasis in Equine Eye: Case Report

A 7-year-old, male pony was presented to our facility with progressive corneal opacity and blepharospasm in the right eye. Vision could not be determined. A thread-like parasite was found in the anterior chamber of the eye. Removal of the parasite through the cornea using the aspiration technique could not be accomplished. The parasite was successfully removed by making a stabbing incision, as an alternative, and was identified as belonging to the genus Setaria. In this report, details of the surgical procedures used together with surgical complications have been discussed. Vision was restored in the right eye postoperatively, though local corneal opacity still persists.     

Polymorphism Analysis of Microsatellites Associated with Seven Candidate Genes for Equine Cryptorchidism

Association of seven candidate genes with cryptorchidism was investigated in the Thoroughbred. A pedigree composed of 23 cryptorchids and 24 nonaffected horses, sharing a common ancestor, was constituted. Sixteen microsatellite markers were developed either from bacterial artificial chromosomes (BAC) isolated for each candidate gene or by in silico screening. DNA from our pedigree was genotyped for these microsatellites. Statistical analysis of the allelic and genotypic frequencies observed with these markers did not reveal any association between the candidate genes and the cryptorchidism phenotype in our horse panel.     

Ultrasonographic Evaluation of Equine Ocular Diseases: A Retrospective Study of 38 Eyes

Ocular ultrasonography in horses represents a valuable imaging diagnostic tool for the diagnosis of intraocular and periocular diseases, particularly when cornea or lens opacities preclude ophthalmoscopy of deeper structures. The authors studied normal and pathological aspects of the eye. Nineteen horses with opacities of the dioptric structures underwent an ultrasound examination. This technique allowed the diagnosis of a posterior synechia (1), cataracts (8), vitreous opacities (6), retinal detachment (3), and a foreign body (1). Ultrasonography provided helpful information about the structure and vascular pattern when the conventional ophthalmic evaluation was unable to achieve a correct diagnosis.     

Multiple Hypersensitivities Including Recurrent Airway Obstruction,Insect Bite Hypersensitivity,and Urticaria in 2 Warmblood Horse Populations

Background

Multiple hypersensitivities (MHS) have been described in humans, cats, and dogs, but not horses.

Hypotheses

Horses suffering from recurrent airway obstruction (RAO), insect bite hypersensitivity (IBH), or urticaria (URT) will have an increased risk of also being affected by another one of these hypersensitivities. This predisposition for MHS also will be associated with decreased shedding of strongylid eggs in feces and with a single nucleotide polymorphism (SNP BIEC2‐224511), previously shown to be associated with RAO.

Animals

The first population (P1) included 119 randomly sampled horses representative of the Swiss sporthorse population; the replication population (P2) included 210 RAO‐affected Warmblood horses and 264 RAO‐unaffected controls. All horses were Warmbloods, 14 years or older.

Methods

Associations between disease phenotypes (RAO, IBH, URT, MHS) fecal egg counts, the SNP BIEC2‐224511 as well as management and environmental factors were investigated.

Results

In P1, RAO‐affected horses had a 13.1 times higher odds ratio (OR) of also suffering from IBH (P = .004). In P2, the respective OR was 7.4 (P = .002) and IBH‐affected horses also showed a 7.1 times increased OR of concomitantly suffering from URT (P < .001). IBH, URT, and MHS phenotypes were significantly associated with the absence of nematode eggs in the feces.

Conclusions and Clinical Importance

This is the first report of MHS in horses. Specifically, an increased risk for IBH should be expected in RAO‐affected horses.     

Lack of Detectable Equine Herpesviruses 1 and 2 in Paraffin-Embedded Specimens of Equine Sarcoidosis

Background: Equine sarcoidosis is a rare, multisystemic, noncaseating, granulomatous and lymphoplasmacytic disease of unknown etiology. A recent report described a horse with granulomatous skin disease displaying histologic, electron microscopic, and polymerase chain reaction (PCR) findings consistent with equine herpesvirus 2 (EHV-2).
Objective: To investigate the presence of EHV-2 and equine herpesvirus 1 (EHV-1) in 8 horses with sarcoidosis.
Animals: Eight horses with sarcoidosis, reported previously.
Methods: Retrospective study. PCR assays of the tissues were performed to detect DNA associated with EHV-1 and EHV-2. For both herpesviruses the target was their respective glycoprotein B gene. Positive controls consisted of DNA from viral cultures of culturettes from naturally occurring respiratory infections of EHV-1 and EHV-2.
Results: The PCR analyses for both equine herpesviruses' DNA were negative in all 8 horses.
Conclusion: The failure to detect DNA from EHV-1 and EHV-2 in paraffin-embedded skin of these 8 horses does not discount EHV-1 or EHV-2 as causing some cases of ES, but lends support to the presumably multifactorial etiologic nature of the disease.     

A Case of Equine Aspergillosis: A Novel Sampling Procedure for Diagnosis

Aspergillus spp. may induce equine respiratory infections such as fungal pneumonia, guttural pouch mycosis, and systemic infection in immunocompromised individuals. This study describes a case of probable respiratory aspergillosis in a horse presenting clinical signs of the upper airway disease different from those previously reported. Nasopharyngeal swabs and guttural pouch centesis were performed, and Aspergillus flavus was isolated and identified. Following 30 days of pharmaceutical treatment with itraconazole, clinical signs resolved. Results suggested that aspergillosis should be included in the differential diagnosis of upper airway infections, guttural pouch centesis may be useful to make a correct diagnosis, and itraconazole is efficacious in the treatment of A flavus infection.     

奶牛抗乳房炎性状候选基因的研究进展

奶牛乳房炎是极其复杂的疾病,是影响奶牛业发展的重要因素。对奶牛乳房炎抗性的研究有利于选育对乳房炎有高抗性的奶牛群,为奶牛业发展提供“绿色通道”,减少长期以来所用的抗生素使用量。本文综述了各位学者从微卫星标记、MHC基因、乳铁蛋白基因和血清转铁蛋白基因来寻找其辅助选择标记的研究情况,介绍控制乳房炎的一个新的切入点。     

Analysis of 8 Sarcomeric Candidate Genes for Feline Hypertrophic Cardiomyopathy Mutations in Cats with Hypertrophic Cardiomyopathy

Background: Hypertrophic cardiomyopathy (HCM) is the most common heart disease in cats. Causative mutations have been identified in the Maine Coon (MC) and Ragdoll breed in the cardiac myosin binding protein C gene (MYBPC3). HCM is thought to be inherited in other breeds.
Hypothesis: That a causative mutation for HCM in the British Shorthair (BSH), Norwegian Forest (NWF), Siberian, Sphynx, or MC cats would be identified in the exonic and splice site regions of 1 of 8 genes associated with human familial HCM.
Animals: Three affected BSH, NWF, Siberians, Sphynx, 2 MC (without the known MC mutation), and 2 Domestic Shorthair cats (controls) were studied.
Methods: Prospective, observational study. Exonic and splice site regions of the genes encoding the proteins cardiac troponin I, troponin T, MYBPC3, cardiac essential myosin light chain, cardiac regulatory myosin light chain, α tropomyosin, actin, and β–myosin heavy chain were sequenced. Sequences were compared for nucleotide changes between affected cats, the published DNA sequences, and control cats. Changes were considered to be causative for HCM if they involved a conserved amino acid and changed the amino acid to a different polarity, acid-base status, or structure.
Results: A causative mutation for HCM was not identified, although several single nucleotide polymorphisms were detected.
Conclusions and Clinical Importance: Mutations within these cardiac genes do not appear to be the only cause of HCM in these breeds. Evaluation of additional cardiac genes is warranted to identify additional molecular causes of this feline cardiac disease.     

A Complementary Radiographic Projection of the Equine Maxillary Sinus

A complementary radiographic projection of the maxillary sinus, known as Wiener Schule, is not known outside of German-speaking countries as a potential complementary projection for a radiographic investigation. A cassette is held by a mechanical device parallel to the nose, with the upper margin above the eye and the head rotated 20° to the affected side. A radiographic angle for a ventral 30° lateral-dorsolateral oblique view, high kilovolt, and low milliampere techniques is recommended. The use of a grid is unnecessary. This oblique radiographic view is useful to image the orbit, the zygomatic bone, the maxillary sinus, the ventral conchal sinus, the conchofrontal sinus, the infraorbital canal, and the roots of the four caudal maxillary cheek teeth (Triadan 108-111 or 208-211). Well positioned, the nasolacrimal canal divides the maxillary sinus in two equal parts. Fluid lines and abnormalities within the named sinus can be detected, quantified, and related to the affected side. The Wiener Schule radiographic projection is a potential complementary tool for radiographic workup and control studies, especially to evaluate therapeutic progress in cases without access to computed tomography.     

猪抗病育种候选基因研究进展

通过抗病育种途径提高猪的抗病力,是避免养猪生产遭受疾病困扰和获得低药物残留猪肉产品的一种很有前景的方法。本文就与猪抗病育种相关的候选基因为受体类基因、免疫相关基因和信号传导基因等的研究进展作一综述,期望能为猪的分子抗病育种提供一些思路。     

Equine Granulocytic Anaplasmosis: A Case Report and Review

A 15 year-old Thoroughbred mare was examined for lethargy, fever, and inappetence of 1-day duration. A hard-bodied tick was removed from the horse. A complete blood count (CBC) demonstrated leukopenia with lymphopenia and thrombocytopenia. Morulae were visualized in circulating granulocytes. A polymerase chain reaction (PCR) confirmed the identity of these organisms as Anaplasma phagocytophilum. The horse was treated symptomatically for fever and inappetence with flunixin meglumine (1.1 mg/kg [0.5 mg/lb]) and oral electrolyte paste. Oxytetracycline (6.6 mg/kg [3 mg/lb] intravenously every 24 hours) treatment was begun as soon as a definitive diagnosis was determined. The mare responded to treatment, but she was switched to oral doxycycline (10 mg/kg [4.5 mg/lb] every 12 hours) after 5 days because of perivascular swelling at the injection site. Complete resolution of clinical signs was seen. There was no evidence of recurrence 1 year later. No additional horses at the farm were affected. The horse in this report presented for lethargy, inappetence, and fever, with limited other abnormalities. This represents a classical presentation of a mild to moderate case of anaplasmosis, which had not previously been reported in Virginia. The disease may be more widespread than has been previously reported, and it should warrant inclusion on a complete differential diagnosis list in a case of fever of unknown origin.