Evaluation of temporal and spatial clustering of horses with Corynebacterium pseudotuberculosis infection

OBJECTIVE: To determine whether horses with Corynebacterium pseudotuberculosis infections that were examined at a veterinary medical teaching hospital between July 1, 1992, and June 30, 1994 had patterns of temporal or spatial clustering. ANIMALS: 134 case and 800 control horses randomly selected from all non-case horses admitted during the study period. PROCEDURES: Admission date and geographic location were determined. Scan, Cuzick & Edwards', and Knox tests were applied to determine whether case horses had patterns of temporal or spatial clustering. RESULTS: For all windows > or = 3 days (134 case horses) and > or = 7 days (subset of 69 case horses), results of the Scan test were significant. Results of Cuzick & Edwards' test were significant for all data sets. A significant spatial cluster of case horses was observed for October, November, and December 1992. Results of the Knox test were significant for temporal intervals between 7 and 56 days and spatial intervals between 4.3 and 6.5 km. Higher Knox(x) proportions were observed for temporal intervals of 0 to 7, 8 to 14, 22 to 28, and 29 to 35 days. CONCLUSIONS: Significant spatial and temporal clustering of horses with C pseudotuberculosis infection was detected. CLINICAL RELEVANCE: Analysis of the results strongly indicates that this disease is directly or indirectly (ie, short distance and time) transmitted. In addition, data analyses indicated an incubation period of 3 to 4 weeks. The disease could be transmitted through horse-to-horse contact or from infected to susceptible horses via insects, other vectors, or contaminated soil.     

Hemodynamic effects of ionized calcium in horses anesthetized with halothane or isoflurane

OBJECTIVES: To evaluate the effects of halothane and isoflurane on cardiovascular function and serum total and ionized calcium concentrations in horses, and to determine whether administration of calcium gluconate would attenuate these effects. ANIMALS: 6 clinically normal adult Thoroughbreds. PROCEDURE: Catheters were inserted for measurement of arterial blood pressures, pulmonary arterial blood pressures, right ventricular pressure (for determination of myocardial contractility), right atrial pressure, and cardiac output and for collection of arterial blood samples. Anesthesia was then induced with xylazine hydrochloride and ketamine hydrochloride and maintained with halothane or isoflurane. An i.v. infusion of calcium gluconate was begun 75 minutes after anesthetic induction; dosage of calcium gluconate was 0.1 mg/kg of body weight/min for the first 15 minutes, 0.2 mg/kg/min for the next 15 minutes, and 0.4 mg/kg/min for an additional 15 minutes. Data were collected before, during, and after administration of calcium gluconate. RESULTS: Halothane and isoflurane decreased myocardial contractility, cardiac index, and mean arterial pressure, but halothane caused greater depression than isoflurane. Calcium gluconate attenuated the anesthetic-induced depression in cardiac index, stroke index, and maximal rate of increase in right ventricular pressure when horses were anesthetized with isoflurane. When horses were anesthetized with halothane, a higher dosage of calcium gluconate was required to attenuate the depression in stroke index and maximal rate of increase in right ventricular pressure; cardiac index was not changed with calcium administration. CONCLUSIONS AND CLINICAL RELEVANCE: I.v. administration of calcium gluconate may support myocardial function in horses anesthetized with isoflurane.     

Clinical and pathologic findings in two draft horses with progressive muscle atrophy, neuromuscular weakness, and abnormal gait characteristic of shivers syndrome

Two Belgian geldings, 4 and 14 years old, respectively, with muscle atrophy, weakness, and abnormal gait characteristic of severe advanced shivers were examined clinically and on necropsy. Neurologic examination revealed no evidence of ataxia, and the clinical diagnosis was neuromuscular weakness and shivers. Necropsies of both horses, including examination of pituitary, brain, spinal cord, spinal roots and ganglia, and peripheral nerves, revealed no gross or histologic abnormalities. Examination of multiple skeletal muscle specimens revealed chronic myopathic changes and periodic acid-Schiff positive, amylase-resistant inclusions within muscle fibers, characteristic of equine polysaccharide storage myopathy. It is suggested that underlying metabolic myopathy may be the cause of muscle weakness and cramping in horses with shivers.     

Evaluation of peritoneal fluid pH, glucose concentration, and lactate dehydrogenase activity for detection of septic peritonitis in horses

OBJECTIVE: To determine whether peritoneal fluid pH, glucose concentration, and lactate dehydrogenase activity can be used to differentiate horses with septic peritonitis from those with nonseptic peritonitis. DESIGN: Prospective study. ANIMALS: 46 horses, including 10 healthy horses, 15 horses with septic peritonitis, and 21 horses with nonseptic peritonitis. PROCEDURE: Peritoneal fluid and blood samples were analyzed for pH, glucose concentration, and lactate dehydrogenase activity. Complete blood cell counts were performed, and peritoneal fluid samples were submitted for bacterial culture. RESULTS: Horses with septic peritonitis had significantly lower peritoneal fluid pH and glucose concentrations than horses with nonseptic peritonitis and healthy horses. Compared with other tests, serum-to-peritoneal fluid glucose concentration differences > 50 mg/dl had the highest diagnostic use for detection of septic peritonitis. Peritoneal fluid pH < 7.3, glucose concentration < 30 mg/dl, and fibrinogen concentration > 200 mg/dl were also highly indicative of septic peritonitis. CLINICAL IMPLICATIONS: Peritoneal fluid pH and glucose concentration can be used to assist in the identification of horses with septic peritonitis. These measurements can provide an early indication of sepsis, especially if cytologic evaluation of peritoneal fluid is unavailable or results are equivocal and peritoneal fluid bacterial culture results are pending.     

Costs of studying veterinary science: a national survey of fourth year veterinary students

OBJECTIVE: To estimate the costs to the student of veterinary education. METHOD: A questionnaire was completed by 180 fourth-year veterinary students from the four veterinary schools in Australia. Frequencies and median costs were estimated using the SAS System for Windows 95. RESULTS: The median direct living costs were about $5000 per academic year, but were higher in Sydney and for those with additional expenses including children, pets and cars. Other costs associated with the course including text books, equipment and travel to practical work were of the order of $1000, and income foregone while doing practical work placed additional burdens on some. More than half the students from Sydney and Murdoch needed to work to provide basic necessities. Most of this work involved interaction with animals or people. The percentage of Queensland and Melbourne students needing to work was lower, 47 and 24 respectively, and fewer of those worked directly with animals or people. The students expected to repay a median of $14,000 after they graduate, with 70% of this being due to the Australian government as part of the Higher Education Contribution Scheme. CONCLUSIONS: Although parents contributed an average of between one-third and one half of the costs of obtaining a veterinary degree, the extent of parental contributions was very uneven and almost one half of all students needed to work to provide basic necessities. The average total debt on graduation was about half the annual starting salary, but those starting the course from 1997 are subject to much higher charges, and their average debt is likely to exceed one year's salary.