Artifacts in digital radiography

Digital radiography is becoming more prevalent in veterinary medicine, and with its increased use has come the recognition of a number of artifacts. Artifacts in digital radiography can decrease image quality and mask or mimic pathologic changes. They can be categorized according to the step during which they are created and include preexposure, exposure, postexposure, reading, and workstation artifacts. The recognition and understanding of artifacts in digital radiography facilitates their reduction and decreases misinterpretation. The purpose of this review is to name, describe the appearance, identify the cause, and provide methods of resolution of artifacts in digital radiography.     

A survey of beef cattle farmers in New Zealand, examining management practices of primiparous breeding heifers

AIM: To obtain an estimate of the incidence of assistance at calving in primiparous (first-calving) beef heifers and the prevalence of breeding heifers at 15 months of age in New Zealand in 2006, and to identify factors contributing to farmers' decisions regarding breeding strategies for heifers, using a survey of beef cattle farmers. METHODS: A questionnaire was sent to farmers listed in a Massey University database and to members of selected breed societies, as well as published in an industry newspaper; 331 valid responses were received. Information was gathered on the age and number of primiparous heifers, number of heifers assisted, and the importance of various reasons for and against breeding heifers at 15 months of age. Respondents were also required to outline the criteria used for selecting bulls to join with heifers, and the strategies used to manage dystocia in primiparous heifers. RESULTS: Sixty-five (95% CI=58-71)% of respondents had only 2-year-old primiparous heifers in 2006, whilst a further 11 (95% CI=8-16)% had both 2- and 3-year-old primiparous heifers. The mean reported incidence of assisted calving was 7.0 (95% CI=6.4-7.5)% for 2-year-old primiparous heifers and 1.7 (95% CI=1.2-2.2)% for 3-year-old primiparous heifers. The reported incidence of assistance at calving within individual herds ranged from 0 to 100% for 2-year-old heifers. Respondents with bull-breeding herds most commonly observed their primiparous 2-year-old heifers twice daily, whilst respondents with commercial herds most commonly observed them once daily during calving. The most important reason for breeding heifers at 15 months of age was increased profit, whereas the most important reason for not breeding them at that age was concern about rebreeding performance of 2-year-old heifers. Estimated breeding value (EBV) for birthweight was the factor considered most frequently when selecting bulls to join with maiden heifers; age of bull and body shape of bull were the next most frequently considered factors. Selection of an appropriate bull was the most common strategy used to manage dystocia in 2-year-old beef heifers. CONCLUSIONS: The majority of respondents calved their heifers at 2 years of age, and increased profit was the primary motivator. Concern about the rebreeding performance of 2-year-old heifers was the most important reason among the remainder of respondents for not breeding heifers at 15 months of age. Dystocia in 2-year-old heifers was not a problem or a minor problem in most herds, but there was much variation amongst herds.     

A modified ab externo approach for suture fixation of an intraocular lens implant in the dog

The goals of canine cataract and lens instability surgery should be to ensure a small incision, minimal tissue trauma, shortened surgical time, maintenance of the anterior chamber, and restoration of emmetropia through the use of a stable intraocular lens specifically designed for the canine eye. While this is usually the case with routine phacoemulsification and in-the-bag intraocular lens implantation, it is often not the case with lens instability, lens luxation or large posterior capsular ruptures. In such cases the incisions are often larger, surgical time and tissue trauma are excessive, and the patient is often left aphakic. The goal of this paper is to present a modified ab externo technique designed to allow removal of the lens and placement of a ciliary sulcus sutured IOL through a small incision, with minimal trauma and shortened surgical time. Use of this technique may allow more canine patients to be emmetropic postoperatively. In addition, the ease of this procedure may encourage earlier removal of an unstable lens and decrease the risk of secondary glaucoma and retinal detachment that occur in association with lens luxation.     

Canine lymphoproliferative disease characterized by lymphocytosis: immunophenotypic markers of prognosis

BACKGROUND: Canine lymphoproliferative disease often presents with lymphocytosis and is immunophenotypically diverse. HYPOTHESIS: Immunophenotype predicts prognosis in canine lymphoproliferative disorders involving circulating lymphocytosis. ANIMALS: Dogs that had peripheral blood evaluation performed by flow cytometry by the Clinical Immunology Service at Colorado State University between 2003 and 2005. METHODS: Outcome data regarding treatment and survival were sought on patients with lymphocytosis comprising a single lymphocyte subset. Ninety-six patients that met the inclusion criteria had sufficient follow-up information to be included in the study. RESULTS: Four main phenotypic classifications were found: CD8+ T-cell, CD21+ B-cell, CD4-8-5+ (aberrant T-cell phenotype), and CD34+ (undifferentiated progenitor). Expression of CD34 predicted poor outcome with median survival of 16 days (P < .0001) compared with other phenotypes. Within the CD8+ phenotype, dogs presenting with a lymphocytosis >30,000 lymphocytes/muL had significantly shorter median survival (131 days) than those presenting with <30,000 lymphocytes/muL (1098 days, P < .0008). Within the T-cell leukemias, there was no difference in outcome between dogs with CD4-8-5+ leukemia and dogs with the CD8+ T-cell phenotype nor was the loss of expression of the pan-leukocyte marker CD45 associated with decreased survival time. A CD21+ lymphocytosis composed of large cells was associated with shorter survival time (129 days) than those with smaller circulating cells (median survival not reached, P < .01). CONCLUSIONS AND CLINICAL IMPORTANCE: Immunophenotyping provides an objective method for determining prognosis in lymphoproliferative disorders characterized by lymphocytosis.     

Chlamydophila psittaci infections in humans during an outbreak of psittacosis from poultry in Germany

In 2005, an outbreak of severe respiratory disease in a mixed poultry flock that was infected with Chlamydophila (C.) psittaci led to dissemination of the infection to at least 100 small poultry farms in 11 districts of Central Germany. At the same time, a total of 24 persons in contact with poultry from one of the flocks reported flu-like symptoms to their physician, thus suggesting zoonotic transmission. Within 3 weeks, seven individuals had to be hospitalized, with three of them requiring intensive care. Analysis of ompA sequences from chlamydial isolates and directly from clinical samples revealed the presence of both genotype A and E/B of C. psittaci at the source of the outbreak and in contact flocks. Genotype A was also detected in the three severely ill patients. The findings of the present study demonstrate the high zoonotic potential of avian chlamydiae. To ensure speedy eradication of psittacosis in poultry flocks and effective treatment of infected humans, fast, sensitive and species-specific detection of the causative agent is essential, as well as close collaboration between regional public health services, attending physicians and the diagnostic laboratories involved.     

Gross and histologic evidence of sharp and blunt trauma in North Atlantic right whales (Eubalaena glacialis) killed by vessels.

Vessel-whale collision events represented the ultimate cause of death for 21 (52.5%) of the 40 North Atlantic right whales (Eubalaena glacialis) necropsied between 1970 and December 2006. Injuries seen in vessel-struck whales fall into two distinct categories: 1) sharp trauma, often resulting from contact with the propeller, and 2) blunt trauma, presumably resulting from contact with a vessel's hull. This study analyzes four trauma cases that resulted from vessel-whale collisions, which together provide a framework for a more critical understanding of lethal blunt and sharp trauma resulting from vessel collisions with right whales. In case no. 1, contact with a propeller resulted in three deep lacerations. The animal survived acute trauma only to succumb nearly 14 years later when the lesions reopened and became infected. In case no. 2, anecdotal reports linked the laceration of large arteries of the peduncle and histologic evidence of perimortem trauma at a bone fracture site to vessel-whale collision trauma. Case no. 3 had a laceration of the oral rete and a fracture of the rostrum. Both of the areas displayed histologic evidence of perimortem blunt trauma. Finally, in case no. 4, an antemortem mandibular fracture, two additional skull fractures, and widespread hemorrhage were consistent with severe blunt trauma. Evidence from each case, including the timing of trauma relative to the time of death and identifying characteristics of both trauma types, are presented. Before this study, no detailed comparative analysis of trauma pathology that resulted from lethal interactions between vessels and right whales had been conducted. This study demonstrates the importance of detailed gross and histologic examination in determining the significance and timing of traumatic events. This work represents a new paradigm for the differential diagnosis of lethal sharp and blunt trauma in right whales hit by ships and will enhance the present understanding of the impact of anthropogenic mortality on this critically endangered species.     

Use of extensible internal device in the femur of young dogs.

An extensible internal device (EID) was developed to preserve growth plate during the treatment of fracture complications or segmental bone loss from tumour resection in children. Since this type of extensible, transphyseal, internal fixation device has only been used in a few paediatric cases; the aim of this study was to evaluate an in vivo canine study, a surgical application of this device, and its interference with longitudinal growth of the non-fractured distal femur. Ten clinically healthy two- to three-month-old poodles weighing 1.5-2.3 kg were used. Following a medial approach to the right distal femur, one extremity of the EID, similar to a T-plate, was fixed in the femoral condyle with two cortical screws placed below the growth plate. The other extremity, consisting of an adaptable brim with two screw holes and a plate guide, was fixed in the third distal of the femoral diaphysis with two cortical screws. The EID was removed 180 days after application. All of the dogs demonstrated full weight-bearing after surgery. The values of thigh and stifle circumferences, and stifle joint motion range did not show any difference between operated and control hindlimbs. The plate slid in the device according to longitudinal bone growth, in all but one dog. In this dog, a 10.5% shortening of the femoral shaft was observed due to a lack of EID sliding. The other dogs had the same longitudinal lengths in both femurs. The EID permits longitudinal bone growth without blocking the distal femur growth plate if appropriately placed.