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Abstract

Objective—To evaluate the efficacy of a customized solution to attenuate intestinal injury following 20% low-flow ischemia and reperfusion in the jejunum of horses.

Animals—10 healthy adult horses.

Procedure—Two 30.5-cm-long segments of jejunum were exteriorized through a ventral midline incision and the mesenteric artery and vein supplying that portion of the intestine were instrumented with flow probes. Blood flow was decreased to 20% of baseline for 90 minutes followed by 90 minutes of reperfusion. In 5 horses, 60 mL of the customized solution was placed in the lumen of each segment (treatment-group horses), and 60 mL of lactated Ringer's solution was placed in the lumen of 5 additional horses (control-group horses). Biopsy specimens were obtained from 1 segment in both groups for histologic evaluation. Aliquots of luminal fluid were obtained from the other segment in both groups for determination of albumin concentrations as an index of mucosal permeability.

Results—Compared with control-group horses, treatment-group horses had a significant decrease in luminal albumin concentration following reperfusion. Although differences in mucosal grades were not significantly different between control- and treatment-group horses, treatment-group horses had significantly greater jejunal villous length and area, compared with that of control-group horses.

Conclusions and Clinical Relevance—Intraluminal administration of the customized solution in the jejunum, compared with lactated Ringer's solution, results in an improvement in histologic findings and mucosal translocation of albumin in horses with mild intestinal injury. (Am J Vet Res 2004;65:485–490)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To characterize isolates of Corynebacterium pseudotuberculosis from horses, cattle, and sheep in Colorado, Kentucky, Utah, and California in samples collected during perceived epidemics of infection (increased numbers of cases identified) in 2002 and 2003, and determine how closely isolates were related and their possible source.

Sample Population—54 isolates of C pseudotuberculosis from 49 horses, 4 cattle, and 1 sheep.

Procedures—Random amplified polymorphic DNA (RAPD) polymerase chain reaction (PCR) assay, PCR assay for the gene encoding the phospholipase D (PLD) toxin, biochemical analyses, and tests for susceptibility to 17 antimicrobial drugs were performed.

Results—All isolates reduced nitrate to nitrite, most yielded positive results for the PLD toxin gene, and all were susceptible to antimicrobial drugs. Ten genetic types were detected by use of RAPD PCR assay; types III to X were isolated from horses, cattle, or both in 1 or more states. Types III and IX were isolated from both horses and cattle. Types VII and VIII were isolated in only 1 state, but the number of isolates in these groups was small. In contrast, all other types were isolated in 2 or more states. All isolates from Utah were type III, but the other 3 states had isolates from more than 1 type.

Conclusions and Clinical Relevance—These data are consistent with a clonally expanding epidemic of infection in Utah and an increase in number of infections caused by multiple strains of C pseudotuberculosis not derived from a single source in the other states. The increase in number of infections could be the result of reporting bias, environmental factors facilitating infection, or host factors such as greater herd susceptibility. (Am J Vet Res 2004;65:1734–1737)

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in American Journal of Veterinary Research

Abstract

Objective—To describe the clinical course and outcome in horses in which Corynebacterium pseudotuberculosis infections were associated with musculoskeletal disease and lameness.

Design—Retrospective case series.

Animals—35 horses.

Procedures—Clinical and clinicopathologic data were collected from horses diagnosed with lameness associated with C pseudotuberculosis infection between 1999 and 2009.

Results—32 (91.4%) horses had grade 4/5 lameness. Three (8.6%) horses had grade 5/5 lameness. Abscesses were diagnosed by clinical or ultrasonographic examination. Abscesses were located in the axillary or triceps region in 25 (71.4%) horses, the stifle region in 2 (5.7%), and the popliteal lymph node in 1 (2.9%). Diffuse lymphangitis was seen in 4 (11.4%) horses, osteomyelitis in 2 (5.7%) horses, and septic arthritis in 2 (5.7%) horses. Horses commonly had clinicopathologic abnormalities characterized by neutrophilia (96.4%), anemia (67.8%), hypoalbuminemia (66.6%), or hyperfibrinogenemia (42.8%). Treatment included surgical drainage of the abscess in 21 (60%) horses, performed under ultrasonography in 20 horses; anti-inflammatory medications in 34 (97.1 %) horses; and antimicrobials in 30 (85.7%) horses.

Conclusions and Clinical RelevanceC pseudotuberculosis infection of the limbs in horses typically results in severe lameness but may have a favorable prognosis. The diagnosis may be challenging, and results of blood work consistent with inflammation are nonspecific, but anemia, hyperglobulinemia, and increased synergistic hemolysis inhibition titers are common. Ultrasonography may localize the lesions and facilitate surgical drainage to alleviate lameness. When C pseudotuberculosis musculoskeletal infection results in osteomyelitis or septic arthritis, the prognosis for survival is poor.

Restricted access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To quantify the number of horses with Corynebacterium pseudotuberculosis infection identified in the United States from January 2003 through December 2012.

Design—Cross-sectional study.

Sample—State veterinary diagnostic laboratory records of 2,237 C pseudotuberculosis culture-positive samples from horses.

Procedures—44 state veterinary diagnostic laboratories throughout the United States were invited by mail to participate in the study. Data requested included the number of C pseudotuberculosis culture-positive samples from horses identified per year, geographic location from which the C pseudotuberculosis culture-positive sample was submitted, month and year of sample submission, breed and age of horses, and category of clinical manifestation (ie, internal infection, external infection, or ulcerative lymphangitis).

Results—Of the 44 invited laboratories, 15 agreed to participate and provided data on affected horses from 23 states. The proportion of C pseudotuberculosis culture-positive samples submitted during 2011 through 2012 (1,213/2,237 [54%]) was significantly greater than that for the period from 2003 through 2010 (1,024/2,237 [46%]). Corynebacterium pseudotuberculosis was recovered from horses in states where the disease has not been previously recognized as endemic. Affected horses were identified year-round. The greatest proportion of C pseudotuberculosis culture-positive samples was identified during November, December, and January (789/2,237 [35%]). No significant association between the clinical form of disease and age or breed of horse was observed.

Conclusions and Clinical Relevance—The occurrence of C pseudotuberculosis infection in horses increased during the 10-year period, and affected horses were identified throughout the United States. Further studies to determine changes in annual incidence and to identify potential changing climatic conditions or vector populations associated with disease transmission are warranted to help control the occurrence and spread of C pseudotuberculosis infection in horses.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine clinical signs, results of diagnostic testing, and outcome in horses with internal Corynebacterium pseudotuberculosis infection.

Design—Retrospective study.

Animals—30 horses.

Procedure—Information pertaining to clinical data, results of diagnostic tests, and costs of hospitalization and treatment was extracted from medical records of affected horses.

Results—Internal C pseudotuberculosis infection was diagnosed on the basis of clinical signs, diagnostic imaging, and clinicopathologic data, including results of serologic tests and bacterial culture. The most common clinical signs were concurrent external abscesses, anorexia, fever, lethargy, weight loss, and signs of respiratory tract disease or abdominal pain. Clinicopathologic abnormalities included a geometric mean reciprocal serum synergistic hemolysin inhibition titer ≥ 512, leukocytosis with neutrophilia, hyperglobulinemia, hyperfibrinogenemia, and anemia. Specific organ involvement was diagnosed in 27 of 30 horses. Affected organs included the liver (18 horses), lungs (12), kidneys (7), and spleen (3); multiple organs were affected in 10 horses. Treatment with antimicrobials for a median of 36 days (range, 7 to 97 days) was usually successful, yielding an overall survival rate of 71%.

Conclusions and Clinical Relevance—Early diagnosis and long-term antimicrobial treatment were important for a successful outcome in horses with internal C pseudotuberculosis infection. Ultrasonographic imaging was an important technique for identifying specific organs affected, aiding in obtaining samples for a definitive diagnosis, and monitoring response to treatment. Pregnant mares with internal infections are at risk for fetal loss. Preexisting chronic organ disease may be associated with a poor prognosis. (J Am Vet Med Assoc 2005;227:441–448)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To describe clinical manifestations of cutaneous and ocular habronemiasis in horses and evaluate outcome of treatment.

Design—Retrospective study.

Animals—63 horses.

Procedure—The diagnosis was made on the basis of history, clinical signs, and identification of calcified concretions (sulfur granules) in lesions. Histologic examination of biopsy specimens was used to confirm the diagnosis. Case horses were compared with a control population of 12,720 horses examined during the same period.

Results—Arabians, gray horses, and horses with diluted coat colors were overrepresented; Thoroughbreds were underrepresented. Lesions were identified most often during the summer and early fall. The medial canthus of the eye, male genitalia, third eyelid, and distal portions of the extremities were the most commonly affected locations. Twenty-five lesions were biopsied, and results of histologic examination were consistent with a diagnosis of habronemiasis. However, nematode larvae were seen in only 11 (44%) biopsy specimens. Treatment consisted of surgical removal (7 horses) or medical treatment (56) consisting of debulking granulation tissue and topical, intralesional, or systemic treatment with corticosteroids. All horses were treated with ivermectin.

Conclusions and Clinical Relevance—Results suggest that cutaneous and ocular habronemiasis should be considered when examining a horse during the summer months with a proliferative, moist, granulomatous lesion. Treatment should be aimed at decreasing the size of the lesion, reducing inflammation, and preventing recurrence. In general, the prognosis was good, and healing occurred within a few weeks. Fly control and regular deworming with ivermectin are recommended to reduce the incidence of habronemiasis. (J Am Vet Med Assoc 2003;222: 978–982)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the effects of an external nasal dilator strip on cytologic characteristics of bronchoalveolar lavage (BAL) fluid in racing Thoroughbreds.

Design—Clinical trial.

Animals—23 Thoroughbred racehorses in active training.

Procedure—Each horse raced on 2 occasions: once while wearing an external nasal dilator strip and once while not. Bronchoalveolar lavage was performed 12 to 18 hours after each race, and BAL fluid was analyzed for RBC and leukocyte counts and hemosiderin content.

Results—Mean ± SEM count of RBCs in BAL fluid when horses raced without the nasal dilator strip (84.6 ± 27.5 cells/µL) was not significantly different from count when they raced with it (41.7 ± 12.2 cells/µL). Horses were grouped as having mild or severe bleeding on the basis of RBC count in BAL fluid after horses raced without the nasal dilator strip. Mean count when horses with severe bleeding raced without the nasal dilator strip (271.0 ± 63.7 cells/µL) was significantly higher than mean count when these horses raced with the strip (93.8 ± 37.6 cells/µL). Mean count of lymphocytes in BAL fluid was significantly lower after horses raced with the external nasal dilator strip.

Conclusions and Clinical Relevance—Results suggest that use of an external nasal dilator strip in Thoroughbred racehorses may decrease pulmonary bleeding, particularly in horses with severe exerciseinduced pulmonary hemorrhage. ( J Am Vet Med Assoc 2004;224:558–561)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate clinical, microbiologic, and pathologic outcomes in mice after inoculation with 4 equine-origin Corynebacterium pseudotuberculosis strains.

Animals—15 C3H/HeJ mice.

Procedures—In a preliminary study, the optimum route of inoculation was determined. In the main study, mice were allocated to 4 treatment groups (3 mice/group). One slow- or rapid-growing equine-origin C pseudotuberculosis strain was inoculated ID into the mice of each treatment group.

Results—All 4 strains had distinct tropism for the liver. Histologic lesions associated with rapid-growing strains included focally extensive unencapsulated areas of acute, massive coagulative necrosis of hepatocytes with intralesional colonies of bacteria and variable portal hepatitis characterized by accumulations of mononuclear and polymorphonuclear inflammatory cells. In contrast, the livers of mice inoculated with slow-growing strains had multiple discrete, randomly distributed foci of hepatocellular necrosis and neutrophilic hepatitis that were considerably less severe than the lesions in the mice inoculated with the rapid-growing strains. Significantly more bacterial colonies were recovered from the organs of mice inoculated with rapid-growing than with slow-growing strains of bacteria. Bacteria were isolated from the liver, spleen, lungs, and mesenteric lymph nodes of mice inoculated with rapid-growing strains and from the liver and lymph nodes of mice inoculated with slow-growing strains.

Conclusions and Clinical Relevance—Study of host-bacteria interactions in hosts that are naturally infected with C pseudotuberculosis is difficult because of underlying genetic variability among animals, expense, and requirements for multiple replicates and control animals. The C3H/HeJ mice may provide a useful means for studying virulence mechanisms of C pseudotuberculosis.

Full access
in American Journal of Veterinary Research