Genetic and phenotypic variation of the equine infectious anemia virus surface unit envelope glycoprotein during disease progression

Lentiviruses are single-stranded RNA viruses generally associated with chronic diseases of the immune and central nervous systems. In contrast to the insidious, progressive nature of most lentiviral diseases, equine infectious anemia virus (EIAV) infection results in rapid onset of a variable disease course in equids. Acute disease is accompanied with high-titered viremia, thrombocytopenia, fever, depression, and inappetance. The chronic stage is usually characterized by recurrent episodes of disease. Equids that survive recurrent disease episodes progress to the inapparent stage of disease where no clinical signs are evident; however, there is persistent, ongoing virus replication. Lentiviruses exist within the host as a population of closely related genotypes, termed a quasispecies. Variation in the virus surface unit envelope glycoprotein (SU) has been demonstrated to contribute to immune evasion of host responses during chronic disease. However, little is known about the SU genotypes and phenotypes associated with disease progression to the inapparent stage of disease. The goal of this research is a genotypic and phenotypic characterization of the SU quasispecies during clinical and inapparent stages of disease. To accomplish this goal, I undertook a longitudinal study of SU variation in a pony experimentally inoculated with the virulent, wild-type, EIAVWyo. There was a marked increase in quasispecies diversity and divergence that coincided with maturation of the immune response and progression to the inapparent stage of disease. Variation was characterized by point mutations in each SU variable region as well as deletion/insertions within the principal neutralizing domain (PND). Genotypes representative of predominant PND variants were used to construct chimeric proviral clones for virus neutralization assays. A type-specific virus neutralizing antibody response was associated with resolution of acute disease. Variants predominant at later stages of disease showed increasing resistance to both type- and group-specific neutralizing antibody. Variants most resistant to group-specific antibody showed reduced replication fitness in vitro. These studies provide evidence that neutralizing antibody selects for resistant SU variants and thereby plays an important role in immune control of virus replication during the inapparent stage of disease

Dandy-Walker-Like Syndrome in a Quarter Horse Colt

A 6-hour-old Quarter Horse colt was examined because of an inability to rise. An uneventful parturition after a normal gestational length from a multiparous mare was reported by the owner. The colt was administered dexamethasone (4 mg) and gentamicin (400 mg) IV and mare’s colostrum (900 mL) PO before referral. Upon examination, the colt (59 kg) was depressed and recumbent. The rectal temperature was 97.6uF, heart rate was 110 beats/min, and the respiratory rate was 40 breaths/min The colt had a prominent domed forehead, but no other significant abnormalities were detected on physical examination. Hematologic and biochemical abnormalities were limited to an increased hematocrit (53%; reference range, 37– 49%), hypoproteinemia (4.3 g/dL; reference range, 5.1– 7.6 g/dL), and an increased serum creatine kinase activity (1597 U/L; reference range, 65–380 U/L). Results of the arterial blood gas analysis were normal. Initial treatment included fluids (500 mL 0.45% NaCl IV q2h), mannitol (1 g/kg IV q12h), amikacin (25 mg/kg IV q24h), ceftiofur (10 mg/kg IV q12h), equine plasma (1000 mL IV once), and feeding via a nasoesophageal tube (500 mL mare’s milk q2h)

Evaluation of locally injected Mycobacterium cell wall fraction in horses with sarcoids

A reformulation of Mycobacterium cell wall fraction immunotherapeutic can be used to successfully treat sarcoids in horses. Sarcoids are reported to be the most common equine skin tumors with tumor type and location influencing the choice of treatment. Wide surgical excision is curative for many tumors, but may not always be feasible. Previous studies have reported sarcoid regression after injection with mycobacterial cell wall immunotherapeutics. A new formulation of the Mycobacterium phlei cell wall fraction immunostimulant (Immunocidin® Equine) was utilized to treat cutaneous tumors in horses. Equids with skin tumors diagnosed as sarcoids were enrolled in the study. Sarcoids were injected at the initial visit with Immunocidin® Equine and subsequently at approximately 2-week intervals. Of 17 cases, 9 cases were completely resolved at the end of the study period evaluation or at time of final follow up (52.9%). Three cases were reported as improved (smaller), but not resolved (17.6%). Three cases were discontinued from the study as the respective masses were growing larger or not resolving (17.6%). One case (5.8%) with two masses had resolution of one mass, whereas the other tumor had a small regrowth 5 months after the last treatment. One case (5.8%) was lost to follow up. All cases had mild to moderate swelling of the injection site, and some cases had discharge after the second, third, or fourth injections. No serious systemic side effects or complications were encountered during the study

Agreement between arterial partial pressure of carbon dioxide and saturation of hemoglobin with oxygen values obtained by direct arterial blood measurements versus noninvasive methods in conscious healthy and ill foals

Objective—To determine agreement between indirect measurements of end-tidal partial pressure of carbon dioxide (Petco2) and saturation of hemoglobin with oxygen as measured by pulse oximetry (Spo2) with direct measurements of Paco2 and calculated saturation of hemoglobin with oxygen in arterial blood (Sao2) in conscious healthy and ill foals. Design—Validation study. Animals—10 healthy and 21 ill neonatal foals. Procedures—Arterial blood gas analysis was performed on healthy and ill foals examined at a veterinary teaching hospital to determine direct measurements of Paco2 and Pao2 along with Sao2. Concurrently, Petco2 was measured with a capnograph inserted into a naris, and Spo2 was measured with a reflectance probe placed at the base of the tail. Paired values were compared by use of Pearson correlation coefficients, and level of agreement was assessed with the Bland-Altman method. Results—Mean ± SD difference between Paco2 and Petco2 was 0.1 ± 5.0 mm Hg. There was significant strong correlation (r = 0.779) and good agreement between Paco2 and Petco2. Mean ± SD difference between Sao2 and Spo2 was 2.5 ± 3.5%. There was significant moderate correlation (r = 0.499) and acceptable agreement between Sao2 and Spo2. Conclusions and Clinical Relevance—Both Petco2 obtained by use of nasal capnography and Spo2 obtained with a reflectance probe are clinically applicable and accurate indirect methods of estimating and monitoring Paco2 and Sao2 in neonatal foals. Indirect methods should not replace periodic direct measurement of corresponding parameters

Effects of intravenous administration of polymyxin B in neonatal foals with experimental endotoxemia

Objective—To evaluate the effect of IV administration of polymyxin B on clinical and serum biochemical variables in foals with experimental endotoxemia. Design—Prospective experimental study. Animals—14 healthy neonatal foals. Procedures—Foals were randomly assigned to a treatment or control group and were administered a single dose of lipopolysaccharide (0.5 μg/kg [0.23 μg/lb]) IV over 30 minutes. The treatment group received polymyxin B (6,000 U/kg [2,727 U/lb], IV) immediately after completion of lipopolysaccharide infusion; the control group was administered an equal volume of saline (0.9% NaCl) solution. Subsequent doses of polymyxin B or saline solution were administered IV at 8 and 16 hours. Blood was collected at various time points, and outcome variables, including heart rate, respiratory rate, rectal temperature, attitude score, WBC count, neutrophil count, lymphocyte count, monocyte count, platelet count, Hct, blood lactate concentration, blood glucose concentration, serum tumor necrosis factor-α concentration, and plasma thromboxane B2 concentration, were measured. Urine was collected prior to and after experimentation to determine whether nephrotoxicosis was associated with treatment. Results—The treatment group had significantly lower blood lactate concentration and serum tumor necrosis factor-α and plasma thromboxane B2 concentrations and had higher blood glucose concentrations and better attitude scores, compared with the control group, at various time points during the study. No other significant differences and no evidence of overt nephrotoxicosis were detected. Conclusions and Clinical Relevance—Administration of polymyxin B IV in healthy neonatal foals challenged with lipopolysaccharide attenuated some clinical and serum biochemical derangements associated with endotoxemia

Preparing Students for Presenting Abroad

The recent move toward globalization of universities in Japan has forced those universities to think of new ways of internationalizing their campuses. One common way of doing this is to promote study abroad programs for their students. As a result, new courses have been developed to help these students prepare for their academic time abroad, writing reports and giving presentations in English, often in a format that is very different from what they would normally do in their home country. This paper will share data on the results of one such class, which utilized a type of learning cycle to assist students in improving their English presentation skills

Clinical and Immunomodulating Effects of Ketamine in Horses with Experimental Endotoxemia

Background:  Ketamine has immunomodulating effects both in vitro and in vivo during experimental endotoxemia in humans, rodents, and dogs. Hypothesis:  Subanesthetic doses of ketamine will attenuate the clinical and immunologic responses to experimental endotoxemia in horses. Animals:  Nineteen healthy mares of various breeds. Methods:  Experimental study. Horses were randomized into 2 groups: ketamine-treated horses (KET; n = 9) and saline-treated horses (SAL; n = 10). Both groups received 30 ng/kg of lipopolysaccharide (LPS, Escherichia coli, O55:B5) 1 hour after the start of a continuous rate infusion (CRI) of racemic ketamine (KET) or physiologic saline (SAL). Clinical and hematological responses were documented and plasma concentrations of tumor necrosis factor-α (TNF-α) and thromboxane B2 (TXB2) were quantified. Results:  All horses safely completed the study. The KET group exhibited transient excitation during the ketamine loading infusion (P \u3c .05) and 1 hour after discontinuation of administration (P \u3c .05). Neutrophilic leukocytosis was greater in the KET group 8 and 24 hours after administration of LPS (P \u3c .05). Minor perturbations of plasma biochemistry results were considered clinically insignificant. Plasma TNF-α and TXB2 production peaked 1.5 and 1 hours, respectively, after administration of LPS in both groups, but a significant difference between treatment groups was not demonstrated. Conclusions and Clinical Importance:  A subanesthetic ketamine CRI is well tolerated by horses. A significant effect on the clinical or immunologic response to LPS administration, as assessed by clinical observation, hematological parameters, and TNF-α and TXB2production, was not identified in healthy horses with the subanesthetic dose of racemic ketamine utilized in this study