Isolation and characterization of an adventitious avian leukosis virus isolated from commercial Marek's disease vaccines

Commercial Marek's disease (MD) vaccines produced by two manufacturers were tested for possible contamination with avian leukosis virus (ALV). Samples of MD vaccines manufactured by two companies (A and B) were received from a breeder company; samples were also received directly from vaccine company B. Using virus isolation tests, samples initially tested positive for subgroup E (endogenous) ALV. However, upon repassage, the vaccines also tested positive for exogenous ALV. The isolated exogenous ALV proved to be a subgroup A virus, as determined by flow cytometry using polyclonal chicken antibodies specific for various subgroups of ALV, and by DNA sequencing of the envelope glygoprotein (gp85). The exogenous ALV isolated from MD vaccines was inoculated in chickens from ADOL lines 15I(5) x 7(1) and 0 to determine its pathogenicity and compare it with that of Rous-associated-virus-1 (RAV-1), the prototype strain of ALV-A. Each chicken from each line was inoculated with approximately 10,000 infectious units of RAV-1 or the ALV-A isolated from vaccines termed B-39 virus at 7th day of embryonation. At hatch, and at 4, 8, and 16 wk of age, chickens were tested for viremia and cloacal shedding; chickens were also observed for ALV-induced tumors within 16 wk of age. Viremia and cloacal shedding results suggest that chickens from both lines were susceptible to infection with either virus. Within 16 wk of age, the proportion of ALV tumors induced by strain B-39 in line 0 and line 15I5 x 7(1) chickens was 0% and 12%, respectively, compared with 62% and 67% in chickens inoculated with RAV-1. The data indicate that commercial MD vaccines produced by two manufacturers were contaminated with endogenous subgroup E and an exogenous subgroup A ALV. Further, data from biological characterization suggest that the ALV-A isolated from commercial MD vaccines is of low oncogenicity, compared with that of RAV-1. GenBank accession numbers: The gp85 gene sequences of ALV isolated from commercial Marek's disease vaccines have been deposited in GenBank and assigned the following accession numbers: A46 subgroup A, DQ412726 ; B53 subgroup A, DQ412727; A46 subgroup E, DQ412728; B53 subgroup E, DQ412729.     

Partial prostatectomy using Nd:YAG laser for management of canine prostate carcinoma

OBJECTIVE: To report a technique for partial prostatectomy by laser dissection and to evaluate outcome and complications in dogs with prostate carcinoma (PCA). STUDY DESIGN: Experimental and clinical case series. ANIMALS: Four normal dogs and 8 dogs with PCA. METHODS: Subcapsular partial prostatectomy, sparing the urethra and the dorsal aspect of the prostatic capsule, using Nd:YAG laser dissection to remove the prostatic parenchyma and control hemorrhage was performed in 4 normal dogs and subsequently in 8 dogs with histologically confirmed PCA. Additional treatment of PCA dogs included local application of interleukin-2 and systemic administration of meloxicam. Prostate size, complications, and survival time were recorded. Laser-associated thermal damage to surrounding tissue was evaluated by histology. RESULTS: In normal dogs, no damage to the dorsal prostatic capsule or urethra was detected. In PCA dogs, median survival was 103 days (range, 5-239 days). Three dogs died from complications within 16 days, whereas 5 (median survival, 183 days; range, 91-239 days) had improvement or resolution of clinical signs. Urinary incontinence did not occur. CONCLUSION: Laser assisted subcapsular partial prostatectomy can be performed in dogs with PCA without development of postoperative incontinence. CLINICAL RELEVANCE: Subcapsular partial prostatectomy is a potential palliative treatment for PCA in dogs and may lead to the resolution of clinical signs for several months.     

Correlation of magnetic resonance images with anatomic features of the equine tarsus

OBJECTIVE: To correlate anatomic features of the equine tarsus identified in plastinated sections with images obtained via magnetic resonance imaging (MRI). ANIMALS: 4 horses. PROCEDURE: MRI (1.5-Tesla magnet) of the tarsus was performed on the pelvic limbs of 4 clinically normal horses following euthanasia. After imaging, tarsocrural joint spaces and vasculature were injected with colored latex. Sagittal and transverse sections of the tarsi were plastinated to facilitate interpretation of MR images. RESULTS: Relevant anatomic structures were identified and labeled on the plastinated tissue slices and corresponding MR images. Results indicated high correlations between MRI findings and those of plastinated sections. CONCLUSIONS AND CLINICAL RELEVANCE: The data obtained provided certain reference standards for normal anatomic structure sizes and positions in the equine tarsus. This information may aid future physiologic or clinical studies of this joint.