Transvenous occlusion of patent ductus arteriosus in a domestic chicken (Gallus gallus).

A 2.5-year-old intact female Marans domestic chicken was presented for lethargy, open beak breathing, and hyporexia. Echocardiography noted left atrial and left ventricular enlargement and computed tomography angiography revealed a type III left-sided patent ductus arteriosus. Retrograde catheterization of the ductus was performed via percutaneous access of the right external jugular vein, and transvenous ductal occlusion was achieved using an 8-mm Amplatzer™ Vascular Plug 4. Transient bradycardia and hypotension occurred during right heart catheterization, which were successfully treated with atropine and epinephrine. A two-week follow-up postoperative cardiac computed tomography scan confirmed appropriate placement of the occluder within the ductus, and echocardiography demonstrated reduced left heart size. The chicken showed an improvement in clinical signs and remains apparently well six months after the intervention. This report describes the computed tomographic findings of a patent ductus arteriosus in an avian species, minimally invasive transvenous closure of this congenital anomaly with a low-profile occlusion device, and the associated challenges and considerations specific to cardiac intervention in an avian patient.

Comparison of dynamic and resting endoscopy of the upper portion of the respiratory tract in 57 Thoroughbred yearlings.

REASONS FOR PERFORMING THE STUDY: Endoscopic examination of Thoroughbred (TB) yearlings is performed routinely to determine the suitability of horses for racing and to ensure that the conditions of sale are satisfied. However, previous research has demonstrated that resting endoscopic examination can be inaccurate in the diagnosis of functional pathology of the upper portion of the respiratory tract (URT). OBJECTIVES: To investigate the feasibility of performing dynamic overground endoscopy in a group of TB yearlings and to compare the results of resting and dynamic endoscopic examination of the URT. STUDY DESIGN: Prospective cohort study. METHODS: Resting (pre- and post exercise) and exercising endoscopy was performed on 57 TB yearlings at a single training yard. Observed abnormalities were recorded and graded. The results of resting and dynamic examination were compared. RESULTS: Dynamic overground endoscopy was well tolerated and was performed with few complications. Laryngeal asymmetry (29 cases) was the most common abnormality identified at rest, while intermittent dorsal displacement of the soft palate (IDDSP; 19 cases) was the most common at exercise. Significant variation in laryngeal function and variation in the occurrence of IDDSP was noted between examinations. Other potentially significant pathology that was not noted at rest but was present during exercise included collapse of the apex of the corniculate process, pharyngeal collapse and cricotracheal ligament collapse. The occurrence of IDDSP at exercise was significantly associated with epiglottic structure grade>2 and a recent history of respiratory tract infection. CONCLUSIONS: Dynamic overground endoscopy is safe and potentially useful when assessing URT function in TB yearlings. Significant variations in the results of endoscopy at rest and during exercise were identified, which indicate that resting endoscopy may not be sufficient to predict the occurrence of pathology during exercise. POTENTIAL RELEVANCE: Dynamic overground endoscopic examination could be considered a suitable means of assessing URT function in TB yearlings and may provide additional pertinent information to that obtained during standard resting examination.

Dynamic respiratory endoscopy in 67 Thoroughbred racehorses training under normal ridden exercise conditions.

REASONS FOR PERFORMING STUDY: There are potential advantages to imaging the upper portion of the respiratory tract (URT) of horses during ridden exercise. With the advent of a wireless endoscope, this is now possible. However, there has been no detailed validation of the technique and findings have not been compared to ridden speed. OBJECTIVES: To assess the combined use of a Dynamic Respiratory Scope (DRS) and global positioning system (GPS) receiver for examining the URT of a group of Thoroughbred racehorses randomly selected from a single flat racehorse training establishment. METHODS: Horses were selected randomly from a population of Thoroughbred horses in training at the same training yard. Endoscopic images of the URT were recorded during a ridden exercise test on an 'all-weather-gallop' and were reviewed post testing. Speed was measured using a wrist mounted GPS receiver. RESULTS: A total of 67 (34%) of the 195 horses in training were examined. Endoscopic findings included: normal URT function (44 cases); dorsal displacement of the soft palate (DDSP) (13 cases); laryngeal asymmetry (4 cases); and axial deviation of the aryepiglottic folds (3 cases). Maximum speed obtained by individual horses ranged from 41.8-56.3 km/h. Ridden speed was variably affected by DDSP. CONCLUSIONS: The DRS provides a safe effective system for imaging the equine URT during ridden exercise at speed. The abnormalities of the URT identified were similar to those observed during treadmill endoscopy studies reported in the literature. The effect of URT abnormalities on ridden speed requires further investigation. POTENTIAL RELEVANCE: This technique can be used to diagnose common causes of URT associated with poor performance in horses during normal training. This has substantial implications for future clinical diagnosis and treatment of URT pathology.

The effect of solvent extraction and sterilization procedure on the tissue response to Dacron velour.

The effects of solvent extraction and sterilization procedure on tissue response to Dacron velour were studied in a canine model, using histomorphometrical techniques. The solvents used for extraction of low molecular weight moieties were either ethanol or water: the sterilization techniques examined were ethylene oxide (ETO) treatment, steam sterilization, and radiofrequency glow discharge (RFGD) treatment. The effect of the sterilization procedure was most marked in the outermost regions (velour) of the implant; no sterilization effects were determined in the capsule or the knitted regions. Velour in the steam sterilized implants had the smallest blood vessel dimensions compared with those that were treated with ETO or RFGD. The effects of different extraction methodologies appeared to be more significant than sterilization effects and were detected further into the implant. That is, not only were extraction effects detected in the capsule and velour, they were also detected in the outer knitted region. Extraction with water resulted in histological responses considered more biologically desirable (thinner capsule, lower giant cell presence, and larger blood vessel diameters) than responses to extraction with ethanol. Neither extraction nor sterilization effects were detected in the inner layers of the knitted region, which were adjacent to the adhesive.

Genetic analysis of Clavibacter toxicus, the agent of annual ryegrass toxicity.

Multilocus enzyme electrophoresis was used to examine the relatedness of 52 isolates of Clavibacter toxicus, the agent of annual ryegrass toxicity. These included 37 Western Australian (WA) field isolates sampled in 3 distinct locations over a 2-year period, and 15 isolates sampled from 6 different host plant species in 3 states in Australia over approximately 8 years. Seventeen reference strains for the related genera Curtobacterium, Rhodococcus and Arthrobacter were examined for comparison. The 69 isolates were divided into 29 electrophoretic types (ETs), separated by genetic distances of 0.06 to 0.81. The C. toxicus isolates fell into 12 ETs, 11 of which formed a tightly clustered group separated by a genetic distance of 0.23 or less. Thirty-one of the WA field isolates of C. toxicus fell into a single ET, and four into another ET. Clavibacter toxicus therefore formed a closely related group which was genetically distinct from the other plant pathogenic species, and a dominant widely disseminated strain of the species was identified in WA.

Herpes simplex virus (HSV) infection of organotypic nerve cell cultures. Tubule-like structures in the nuclei of cells infected with type 2 but not with type 1 virus.

In HSV-2 infected cultures, intranuclear tubule-like structures were found more commonly in fibroblasts and central nervous system (CNS) neurons than in oligodendrocytes, astrocytes, satellite and Schwann cells, but were found least often in peripheral neurons.

Host-cell response to herpes virus infection in central and peripheral nervous tissue in vitro.

In an organotypic nerve cell culture system, all cells in both the central and the peripheral nervous system (CNS, PNS) components supported replication of herpes simplex virus types 1 and 2 (HSV 1, HSV 2). In HSV 1 infection, cellular response was particularly characterized by the formation of small syncytia (which involved neurons) and by the presence of bundles of interwoven fine filaments within the nuclei of infected cells. In HSV 2 infection, groups of parallel tubules characteristically formed in the nuclei of infected cells. All cells in the CNS or PNS succumbed to virus infection, some within 24 h (e.g. oligodendrocytes) and others after 48 h (e.g. neurons), with the exception of astrocytes. Although among the first cells to develop virus nucleocapsids in their nuclei, astrocytes became swollen and filled with increased numbers of bundles of glial filaments within 24 h after infection; by 48 h the actual number of astrocytes was increased by as much as three- to fourfold over the number in controls. The results suggest that astrocytes may have a unique mechanism which modifies virus infection and the cells not only survive, but can also become reactive.

Herpes simplex virus types 1 and 2 in organotypic cultures of mouse central and peripheral nervous system. 2. Electron microscopic observations of myelin degeneration.

Organotypic cultures of mouse spinal cord with attached dorsal root ganglia, which contain both central and peripheral myelin in the one unit of tissue, were infected with HSV 1 or HSV 2 and studied using electron microscopy. Intranuclear viral nucleocapsids and intracytoplasmic enveloped particles were found in the Schwann cells associated with peripheral myelin and in oligodendroglia associated with central myelin. Degeneration of peripheral myelin most commonly involved an asymmetrical swelling of the myelin lamellae, whereas degeneration of central myelin was characterized by a more generalized swelling resulting in separation of the myelin lamellae. Degeneration of both central and peripheral myelin was found in the presence of intact axons which were indistinguishable from those in controls.

Herpes simplex virus types 1 and 2 in organotypic cultures of mouse central and peripheral nervous system. I. Light microscopic observations of myelin degeneration.

Mature mouse spinal cord-ganglion cultures, which contain both peripheral and central nervous system as one unit, were infected with herpes simplex virus type 1 (HSV 1) or type 2 (HSV 2) and observed by bright field microscopy for up to 72 hours. There was degeneration of both central and peripheral myelin in cultures infected with either virus, but the pattern of peripheral myelin degeneration associated with HSV 1-infected cultures was differrnt from that in HSV 2-infected cultures. Type 1 was charcterized by focal dilatations; type 2 by "sausage-shaped" swellings, and the cytopathic effect of HSV 2 both began (6 hours p.i.) and was completed (36 hours p.i.) earlier than in cultures infected with HSV 1 (12 hours and 48 hours p.i. respectively). In central nervous tissue, the apperance of degenerating myelin after infection with HSV 1 was indistinguishable from that in HSV 2-infected cultures, but the rate of myelin loss was greater in cultures infected with the type 2 virus. Evidence is presented which suggests that, at least in the peripheral nervous system,myelin degeneration did not appear to be dependent on neuronal or axonal dysfunction or death, but was a direct result of virus infection.