Pharmacokinetics of liposomal encapsulated buprenorphine suspension following subcutaneous administration to cats

We investigated the effects of liposome encapsulation at prolonging the systemic exposure of buprenorphine following subcutaneous administration in cats. Seven healthy male cats were dosed intravenously with 0.02 mg/kg buprenorphine solution (STD‐BUP), followed 14 days later by a subcutaneous injection of 0.2 mg/kg buprenorphine as a liposomal suspension (SUS‐BUP) containing drug molecules both in liposomes and the suspending vehicle. Buprenorphine time plasma concentration data for both dosing routes were analyzed simultaneously with four compartmental models. Goodness of fit was assessed both graphically and with the Akaike information criterion. The time‐course of intravenous STD‐BUP was biphasic, with a 4.39 h average terminal half‐life. The subcutaneous SUS‐BUP produced plasma buprenorphine concentrations above 0.5 μg/L for more than 96 h, with three distinct peaks in the first 15 h. The model with best fit comprised a central and a peripheral compartment, plus three subcutaneous absorption compartments: one of dissolved drug molecules that were absorbed through a first‐order process, and two of liposome‐encapsulated drug molecules that were transferred to the solution compartment through separate zero‐order processes. Liposomes effectively prolonged the systemic exposure of buprenorphine in cats.     

Increased student self-confidence in clinical reasoning skills associated with case-based learning (CBL)

Second-year veterinary students were surveyed at the beginning and end of a 15-week semester regarding their confidence in performing three clinical reasoning skills: (1) making Problem Lists; (2) making Rule-Out Lists; and (3) selecting appropriate diagnostic tests. Each week during the semester, these skills were practiced in small-group case discussions. Changes in self-confidence were analyzed and studied in light of faculty assessments of student competence in performance of the three skills. RATIONALE: The purpose of the study was to determine if students' self-confidence in performing three clinical reasoning skills increased with practice. METHODOLOGY: On the first and last days of class, students rated their confidence in each of the three skills on a scale of 0 to 10. Mean confidence scores for the whole class both for time points and for each of the three skills were analyzed. RESULTS: There were significant increases in students' self-confidence in all three clinical reasoning skills over the semester each year. A greater percentage of students expressed improved confidence in selecting appropriate diagnostic tests than in the other two skills in three of the four years studied. CONCLUSIONS: Students' self-confidence in performing three clinical reasoning skills improved over the course of a semester in which they practiced the skills in a CBL format. Subjective faculty assessment of students' competence in these skills generally indicated improvement. However, no meaningful conclusions about the correlation of skill competence and student confidence could be drawn because of inadequacies in the measurement of student performance.     

Isolation of Vibrio cholerae from the brain of a feedlot heifer with meningoencephalitis.

A 700-pound, 9-month-old Angus heifer from a feedlot presented with acute neurologic signs, characterized by circling, posterior weakness, and nonresponsiveness, followed by death. Histologically, the frontal lobe and the thalamus contained multiple foci of liquefaction that contained numerous degenerative neutrophils and foamy macrophages. Some of these foci were centered on blood vessels that contained fibrin thrombi and exhibited varying degrees of fibrinoid necrosis of the vessel wall. There was adjacent axonal degeneration and neuronal necrosis characterized by pronounced cytoplasmic eosinophilia, peripheralization of the nuclei, and loss of Nissl substance. Aerobic culture of the brain yielded moderate growth of Vibrio species, which was determined to be Vibrio cholerae by polymerase chain reaction analysis of a 438-base pair fragment of the 16 S ribosomal RNA gene. V. cholerae are motile, gram-negative, curved rod-shaped bacteria. Some strains of V. cholerae are important food- and water-borne bacterial pathogens that produce an often fatal diarrhea in humans. This is the first known case report of V. cholerae meningoencephalitis and cerebral abscessation in a bovine.     

The 2006 American Association of Feline Practitioners Feline Vaccine Advisory Panel report

Vaccination is a medical procedure, and the decision to vaccinate should be based on a risk-based assessment for each cat and each vaccine.     

Glanders--a comprehensive review

Since 1990 the number of glanders outbreaks in race, military and pleasure horses in Asia and South America is steadily increasing. Glanders, which is eradicated in Western Europe, Australia and Northern America, is currently considered a re-emerging disease. Consequently, the disease may be introduced into glanders-free regions by subclinical carriers at any time. The causative agent of glanders, Burkholderia (B.) mallei, is highly contagious and leads to chronic disease in horses whereas in donkeys and mules the disease is acute and often fatal. Occurrence of the disease leads to international trading restrictions and infected animals immediately have to be culled and safely disposed off. In humans B. mallei infection results in a severe clinical course, and is fatal without appropriate therapy. Its pathogenicity makes B. mallei a potential biological agent that may be used in bioterroristic attacks. Due to the eradication of glanders in the second half of the last century, veterinarians in western European countries are no longer familiar with its clinical presentation in solipeds. Having these facts in mind, this review describes the epidemiology, clinical signs, pathology and the current eradication strategy of this interesting zoonosis. Pictures of imported endurance horses infected with glanders taken during an eradication campaign in Dubai, United Arab Emirates, in 2004 illustrate most typical clinical findings.     

Post-thaw viability of european bison (Bison bonasus) semen frozen with extenders containing egg yolk or lipids of plant origin and examined with a heterologous in vitro fertilization assay.

Basic characteristics of European bison (Bison bonasus) semen were described and the efficacies of two extenders-Triladyl, containing egg yolk, and a synthetic extender, containing soybean lipids-were tested for semen cryopreservation. Seven ejaculates were collected by electroejaculation from a 10-yr-old, European bison bull. Each ejaculate was diluted at 37 degrees C to a final concentration of 200 x 10(6) sperm/ml with Triladyl or the synthetic extender. Extended semen samples were frozen according to a standard bull semen freezing protocol. After 2 wk of storage, one straw from each extender and ejaculate was thawed, and postthaw quality was evaluated by individual sperm motility and movement rate, numbers of sperm morphologic abnormalities and intact acrosomes, functional integrity of the sperm membranes determined by hypoosmotic swelling test (HOST), viability (live-dead, eosin-nigrosin stain), and a heterologous in vitro sperm penetration assay (SPA). A total of 600 in vitro-matured bovine oocytes were inseminated with 1 X 10(6) spermatozoa of Holstein semen frozen-thawed in Triladyl (control) or of European bison semen frozen in Triladyl or the synthetic extender. Nuclear status of the oocytes was determined after 18 h of sperm-oocyte coincubation. Extender had no effect on any evaluated parameters of semen after dilution and cooling (4 hr at 5 degrees C) or in postthaw individual motility, quality of movement, and sperm morphology. However, significantly (P < 0.05) higher numbers of spermatozoa with intact acrosomes, intact membranes (HOST), and viable sperm (P < 0.01) were in semen frozen in Triladyl than in the synthetic extender. Mean values for heterologous SPA for bull (control) and for bison semen frozen in the synthetic extender were very much alike-63.3+/-10.6% and 63.1 +/- 15.9%, respectively; bison semen frozen in Triladyl was lower, 43.0+/-24.2% but not significantly different. Cumulative results from a variety of viability assays of diluted/cooled and frozen-thawed semen, including the heterologous SPA, suggest that European bison semen can be successfully frozen in both extenders tested in this study.     

Comparative fluke burden and pathology in condemned and non-condemned cattle livers from selected abattoirs in Zambia

After dissecting 70 condemned and 32 non-condemned cattle livers collected from Lusaka, Chisamba, Mongu and Senanga abattoirs and Turnpike slaughter slab, significantly higher numbers of liver flukes (Fasciola gigantica) (P < 0.001) were found in the condemned livers (mean +/- SD = 100.6 +/- 16.7) than in the non-condemned livers (mean +/- SD = 0.7 +/- 0.5). Liver flukes found in 9.4% of the non-condemned livers suggest that abattoir records of liver inspection may underestimate F. gigantica infections. Average faecal fluke egg counts from animals with condemned livers (5 eggs per gram [EPG]) were significantly higher (P < 0.001) than in animals with non-condemned livers (0.8 EPG). No correlation was found between egg counts and number of flukes. Fibrosis and calcification were common in condemned livers, being severest in the vicinity of the bile ducts. Only two (6.3%) of the non-condemned livers showed pathological changes on the liver edges. The severe liver damage and high worm burden may explain low production levels experienced in cattle in Zambia maintained under traditional systems of management where worm control and good management programmes are rarely practiced.     

Efficacy of a killed vaccine for the control of paratuberculosis in Australian sheep flocks

A field trial was undertaken from 1999 until 2004 to determine the efficacy of a killed M. a. paratuberculosis vaccine, Gudair, for the control of ovine Johne's disease (OJD) in merino sheep run under Australian pastoral conditions. On each of three farms experiencing significant OJD losses (5-15% per annum), 200 merino lambs (age 1-4 months) were vaccinated, and 200 lambs were left unvaccinated. Animal assessments and sample collections were conducted twice yearly until 4 or 5 years of age. The impact of vaccination on mortality rate, faecal shedding of M. a. paratuberculosis (by pooled and individual faecal culture), liveweight, wool productivity, vaccine injection site lesions and cellular (BOVIGAM) and humoral (PARACHEK) immunity was examined. Vaccination stimulated cell-mediated and humoral immune responses, reduced mortalities due to OJD by 90% and delayed faecal shedding for the first year post-vaccination. Thereafter, the prevalence of shedders among vaccinates was reduced by 90%. The numbers of M. a. paratuberculosis excreted by the vaccinated groups were also reduced by at least 90% at most sampling times. However, high levels of excretion by vaccinates occurred on some occasions, and although only 7 of 600 vaccinates died from OJD, all 7 had multibacillary lesions. Thus there remains a risk that some vaccinated sheep will transfer the disease. Small reductions in liveweight were found in vaccinated lambs in the first year, but there was little effect on wool production. Vaccine injection site lesions were detected in almost 50% of sheep after 2 months, and these persisted for at least 4 years in 20-25% of vaccinates. Data from this trial enabled the registration of Gudair in Australia in 2002 and underpins the pivotal role of vaccination in the current management of OJD.     

Risk factors associated with renal insufficiency in horses with primary gastrointestinal disease: 26 cases (2000-2003)

OBJECTIVE: To identify factors associated with renal insufficiency in colic- or colitis-affected horses with high serum creatinine (SCr) concentrations evaluated at a referral hospital. DESIGN: Retrospective case series. ANIMALS: 167 colic- or colitis-affected horses (88 represented a random sample [hospital population], and 79 had high SCr concentration at initial evaluation [study population]). PROCEDURE: Medical records were reviewed. Data collected included signalment; physical examination, clinicopathologic, and diagnostic findings; and outcome. The study population was categorized on the basis of whether SCr concentration did (AR group; n = 53) or did not (PA group; 26) normalize within 72 hours of fluid therapy. Characteristics of the study and hospital populations were compared. RESULTS: Males and Quarter Horses were significantly overrepresented in the study population. Compared with the hospital population, study-population horses were significantly more likely to have colitis, gastric reflux, and diarrhea at initial evaluation. Initial mean SCr concentration in the PA group was significantly higher than the AR group; identification of gastric reflux, abnormal rectal examination findings, and hypochloremia were significantly associated with persistent azotemia after 72 hours of fluid therapy. Compared with the AR group, PA group horses were 3 times as likely to die or be euthanized. CONCLUSIONS AND CLINICAL RELEVANCE: In colic- or colitis-affected horses, factors associated with renal insufficiency included gastric reflux, abnormal rectal examination findings, or hypochloremia initially; prognosis for horses in which azotemia resolves within 72 hours of treatment appears to be better than for horses with persistent azotemia.