Department of Large Animal Clinical Sciences
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- Heifer inventory and the economics of replacement rearingBailey, Thomas L.; Currin, John F. (Virginia Cooperative Extension, 1999)
- Milk production evaluation in first lactation heifersBailey, Thomas L.; Currin, John F. (Virginia Cooperative Extension, 1999)
- Predicting bull fertilityWhittier, W. Dee; Bailey, Thomas L. (Virginia Cooperative Extension, 2000)
- Current strategies in parasite control in Virginia beef cattleCurrin, John F.; Whittier, W. Dee (Virginia Cooperative Extension, 2000)
- Beef cow/calf herd health program and calendarWhittier, W. Dee; Currin, John F. (Virginia Cooperative Extension, 2000)
- Feeder and stocker health and management practicesCurrin, John F.; Whittier, W. Dee (Virginia Cooperative Extension, 2000)
- Equine neonatal sepsis: The pathophysiology of severe inflammation and infection.McKenzie, H. C.; Furr, M. O. (Veterinary Learning Systems, 2001-07-01)Although the clinical syndrome of sepsis is a major problem in equine neonates, the pathophysiology of this condition remains incomplete. Because the term sepsis describes a broad range of disorders with different underlying causes and often different prognoses, the understanding of this process is further complicated. Continued progress is being made, how- ever, in defining the syndromes associated with sepsis and in elucidating the mechanisms in- volved in these processes. Attempts at modulating the septic process by interfering with the action of bacterial toxins or the production or activity of individual mediators have not been successful, thereby reinforcing that this is a multifactorial response. Fortunately, the complex interactions of intra- and extracellular messengers leading to clinical sepsis continue to be defined. An increased understanding of the processes involved in the septic response may aid in the identification of patients with these syndromes as well as improve the effectiveness of treatment regimens.
- Management of Cow-Calf Production on Reclaimed Surface-Mined LandWhittier, William Dee; Gerken, Hubert J. Jr.; Zipper, Carl E. (Virginia Cooperative Extension, 2002-10-12)Summarizes a number of cattle management issues that are important to mined-land cattle producers in Virginia.
- Protective immune response to experimental infection with Sarcocystis neurona in C57BL/6 miceWitonsky, Sharon G.; Gogal, Robert M.; Duncan, Robert B.; Lindsay, David S. (American Society of Parasitology, 2003-10)Immunocompetent C57BL/6 mice were infected with Sarcocystis neurona merozoites to assess the protective immune response to active infection. Using a direct agglutination test, all infected mice seroconverted to S. neurona merozoite antigens by day 14 postinfection (PI). Further, mice developed splenomegaly and bilateral symmetrical lymphadenopathy by day 14 PI, which appeared to be resolving by day 28 PI. Histologic analysis revealed a marked increase in germinal center formation in the spleen and lymph nodes by day 14 PI. Corresponding to gross and histopathological changes, the percentage of B-cells decreased significantly by day 14 PI but then increased significantly and persisted at day 28 PI in the blood, spleen, and multiple lymph nodes. There was a sharp nonspecific significant decrease in CD4 percentages by day 14 PI in the blood, spleen, and lymph nodes. Early-activation CD8 lymphocytes (CD62/CD8) were significantly down-regulated coinciding with a significant compensatory up-regulation of memory (CD44/CD8) lymphocytes in multiple organs. We propose that the protective cell-mediated immune response to S. neurona involves both CD4 and CD8 cells, with CD8 lymphocytes appearing to play a more critical role.
- Immunopathologic effects associated with Sarcocystis neurona-infected interferon-gamma knockout miceWitonsky, Sharon G.; Gogal, Robert M.; Duncan, R. B.; Lindsay, David S. (American Society of Parasitology, 2003-10)Interferon-gamma knockout (IFN-gamma KO) mice were infected with Sarcocystis neurona merozoites to characterize the immunopathology associated with infection. By day 14 postinfection (PI), mice developed splenomegaly and lymphadenopathy, characterized by marked lymphoid hyperplasia with increased numbers of germinal centers. Additional histopathologic changes included increased extramedullary hematopoiesis, multifocal mixed inflammatory infiltrates in the liver, perivascular infiltrate of the liver and lung, and interstitial pneumonia. The total number of B-cell splenocytes (P < 0.05) and the percentage of B-cells increased on day 14 PI in the spleen and on day 28 PI in the lymph nodes (P < 0.05). By day 28 PI, the number of B-cell splenocytes decreased significantly. A non-subset-specific decrease in percentages of CD4 lymphocytes throughout all lymphoid organs was observed on day 14 PI. However, total CD4 and CD44/CD4 splenocytes increased significantly by day 28 PI. Early-activation CD8 lymphocytes were reduced in the blood and spleen, whereas memory CD8 lymphocyte percentages and total numbers were significantly increased. On the basis of the results, we propose that S. neurona-infected IFN-gamma KO mice are immunocompromised and unable to clear the infection. Thus, they develop B-cell exhaustion and a delayed, but sustained. increased number of memory CD4 and CD8 lymphocytes due to chronic antigen stimulation.
- Prevalence of agglutinating antibodies to Sarcocystis neurona in raccoons (Procyon lotor) from an urban area of VirginiaHancock, K.; Zajac, Anne M.; Elvinger, Francois; Lindsay, David S. (American Society of Parasitology, 2004-08)Equine protozoal myeloencephalitis is the most important protozoan disease of horses in North America and is usually caused by Sarcocystis neurona. Natural and experimentally induced cases of encephalitis caused by S. neurona have been reported in raccoons (Procyon lotor) and raccoons are an intermediate host for this parasite. A 3-yr-long serological survey was conducted to determine the prevalence of agglutinating antibodies to S. neurona in raccoons collected from Fairfax County, Virginia, a suburban-urban area outside Washington, D.C. Samples from 469 raccoons were examined, and agglutinating antibodies ( greater than or equal to 1:50 dilution) were found in 433 (92.3%) of the raccoons. This study indicates that exposure to S. neurona is high in this metropolitan area.
- Prevalence of antibodies to Trypanosoma cruzi in raccoons (Procyon lotor) from an urban area of northern VirginiaHancock, K.; Zajac, Anne M.; Pung, O. J.; Elvinger, Francois; Rosypal, A. C.; Lindsay, David S. (American Society of Parasitology, 2005-04)Raccoons (Procvon lotor) are reservoir hosts for Trypanosoma cruzi. A 3-yr-long serological survey was conducted to determine the prevalence of antibodies to this zoonotic parasite in raccoons collected from Fairfax County. Virginia, a suburban/urban area outside Washington, D.C. Serum samples from 464 raccoons were examined for T. cruzi antibodies at a 1:40 dilution with an indirect fluorescent antibody test (IFAT) and Brazil strain T. cruzi amastigotes and trypomastigotes as antigen. A positive IFAT test was found in 154 (33%) of the 464 samples. The yearly prevalence was 49 of 132 (37%) in 2000; 19 of 120 (16%) in 2001; and 86 of 212 (41%) in 2002. Our study indicates that raccoons in this area of Virginia are frequently exposed to T cruzi.
- Prevalence of antibodies to Toxoplasma gondii in raccoons (Procyon lotor) from an urban area of northern VirginiaHancock, K.; Thiele, L. A.; Zajac, Anne M.; Elvinger, Francois; Lindsay, David S. (American Society of Parasitology, 2005-06)Raccoons (Procyon lotor) are intermediate hosts for Toxo-plasma gondii, and clinical toxoplasmosis in raccoons has been reported. A 2-yr serological survey was conducted to determine the prevalence of antibodies to T. gondii in raccoons collected from Fairfax County, Virginia, a suburban/urban area outside Washington, D.C. Serum samples from 256 raccoons were examined for T. gondii antibodies at a 1:50 dilution using the modified direct agglutination test. Results indicated that 216 (84.4%) of the raccoons had been exposed to T. gondii. Our results indicate that raccoons in this area of Virginia are frequently exposed to T gondii. Domestic cats were common in the study area and may have served as a source of oocysts for raccoons and the food items of raccoons.
- Recognition and Treatment of Bovine Respiratory Disease ComplexCurrin, John F.; Whittier, W. Dee (Virginia Cooperative Extension, 2005-09-01)The recognition and treatment of Bovine Respiratory Disease Complex is vital to the economic well-being of the stocker cattle producer.
- Foot Rot in Beef CattleCurrin, John F.; Whittier, W. Dee; Currin, Nancy (Virginia Cooperative Extension, 2005-09-01)Foot rot is a common disease of cattle that can cause severe lameness and decreased weight gain. Other common names for the disease are sore foot and foul foot.
- Strategic Use of Antibiotics in Stocker CattleCurrin, John F. (Virginia Cooperative Extension, 2005-09-01)Bovine respiratory disease complex remains the most important health issue facing stocker-cattle producers. This publication discusses the use of antibiotics in treating BRDC.
- Calving Emergencies in Beef Cattle: Identification and PreventionWhittier, W. Dee; Currin, Nancy; Currin, John F.; Hall, John B. (Virginia Cooperative Extension, 2005-09-01)Calving difficulty, technically called dystocia, is a major cause of death loss in cow-calf herds. Studies indicate that dystocia is responsible for 33 percent of all calf losses and 15.4 percent of beef cattle breeding losses.
- Current Strategies in Parasite Control in Virginia Beef CattleWhittier, W. Dee; Currin, John F. (Virginia Cooperative Extension, 2005-09-01)Many advances have been made in the field of livestock parasite control over the past few years. Because parasites decrease production, control of parasites can have a direct economic impact on beef cattle operations.
- Beef Cow/Calf Herd Health Program and CalendarWhittier, W. Dee; Currin, John F. (Virginia Cooperative Extension, 2005-09-01)Losses caused by disease represent a major obstacle to the profitability of many cow/calf beef operations. It is widely agreed that prevention rather than treatment is the most economical approach to keeping disease losses low.
- Predicting Bull FertilityWhittier, W. Dee; Bailey, Thomas L. (Virginia Cooperative Extension, 2005-09-01)Discusses the Breeding Soundness Examination, a valuable tool or predicting fertility of bulls and increasing herd reproductive performance.