Scielo RSS <![CDATA[Journal of the South African Veterinary Association ]]> http://www.scielo.org.za/rss.php?pid=1019-912820090001&lang=es vol. 80 num. 1 lang. es <![CDATA[SciELO Logo]]> http://www.scielo.org.za/img/en/fbpelogp.gif http://www.scielo.org.za <![CDATA[<b>Computer simulations of propofol infusions for total intravenous anaesthesia in dogs</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1019-91282009000100001&lng=es&nrm=iso&tlng=es The volatile anaesthetic agents halothane, isoflurane and enflurane are all chlorofluoro-carbons and according to international treaties, their emission into the atmosphere will be prohibited from the year 2030. The agents desflurane and sevoflurane are fluorinated hydrocarbons and act as greenhouse gases. The future of veterinary anaesthesia could be dependent on the development of total intravenous anaesthesia. Drugs utilised in total intravenous anaesthesia (TIVA) should have a short duration of action and no tendency to accumulate in the body. Propofol has been the dominant agent used. Computer technology has enabled targeted plasma concentration controlled infusions to replace manual infusion regimens. This study simulated the pharmacokinetics of various infusion regimens similar to those used in clinical practice using previously published pharmocokinetic data. Bolus doses of 0, 4, 6 and 8 mg/kg were simulated in combination with infusion rates of 0, 0.2, 0.3 and 0.4 mg/kg/min for either 240 or 1440 min. The computer was also programmed to maintain a steady state plasma concentration based on the previous simulated data. Generated data were then compared with published data. Changes in the context-sensitive half-life for propofol were also evaluated. Results showed that the generated data were similar to published data. A decrease in plasma concentration to levels associated with a light plane of anaesthesia was evident even when the highest bolus dose and infusion rate were used. There was a slow rise in plasma concentration when only an infusion was used. A lightening of anaesthetic plane may be evident early in the course of TIVA and careful monitoring of anaesthetic depth is required. As the duration of the infusion increased, plasma concentration steadily rose but achieved 95% of the steady state by 204 min. The most dramatic changes in plasma concentration occurred in the first hour of an infusion. Similarly, the infusion rates decreased most in the first 70 min. Most changes in anaesthetic depth are likely to occur early in the course of TIVA and careful observation of anaesthetic depth is required. <![CDATA[<b>Sedative and cardiopulmonary effects of acepromazine, midazolam, butorphanol, acepromazine-butorphanol and midazolam-butorphanol on propofol anaesthesia in goats</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1019-91282009000100002&lng=es&nrm=iso&tlng=es The sedative, propofol-sparing and cardiopulmonary effects of acepromazine, midazolam, butorphanol and combinations of butorphanol with acepromazine or midazolam in goats were evaluated. Six healthy Boer - Indigenous African crossbreed goats were by randomised cross-over designated to 6 groups: Group SAL that received saline, Group ACE that received acepromazine, Group MID that received midazolam, Group BUT that received butorphanol, Group ACEBUT that received acepromazine and butorphanol and Group MIDBUT that received midazolam and butorphanol as premedication agents intramuscularly on different occasions at least 3 weeks apart. The degree of sedation was assessed 20 minutes after administration of the premedication agents. Thirty minutes after premedication, the dose of propofol required for induction of anaesthesia adequate to allow placement of an endotracheal tube was determined. Cardiovascular, respiratory and arterial blood-gas parameters were assessed up to 30 minutes after induction of general anaesthesia. Acepromazine and midazolam produced significant sedation when administered alone, but premedication regimens incorporating butorphanol produced inconsistent results. The dose of propofol required for induction of anaesthesia was significantly reduced in goats that received midazolam alone, or midazolam combined with either acepromazine or butorphanol. The quality of induction of anaesthesia was good in all groups, including the control group. Cardiovascular , respiratory and blood-gas parameters were within normal limits in all groups and not significantly different between or within all groups. : sedation with midazolam alone, or midazolam combined with either acepromazine or butorphanol significantly reduces the induction dose of propofol with minimal cardiopulmonary effects in goats. <![CDATA[<b>Trends in udder health and emerging mastitogenic pathogens in South African dairy herds</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1019-91282009000100003&lng=es&nrm=iso&tlng=es The aim of this study was to retrospectively analyse the results of milk samples obtained from South African dairy herds during the period 1996 to April 2007 in order to identify possible trends in isolates of microorganisms and their pathogenicity under field conditions. Milk samples were obtained from 7 of the 9 provinces in South Africa where there are low numbers of dairy cows. Although there is scientific limitation to a country wide survey, such as the variation in herd size, management skills, parity, milk yield, milking frequency and other parameters, the size of this database helps to give a fair indication of general udder health in South Africa. Cytology and routine bacteriology were performed on 379 000 milk samples of lactating cows and bacteriology on 11 946 samples from non-lactating cows. According to the results obtained, mastitis did not decrease in South Africa over the test period. The prevalence of mastitis and teat canal infection was lowest in 2002. Mastitis and teat canal infection increased from 2002 to 2006 from 8.1 % and 24.1 % to 15.4 and 30.0 % respectively. The percentage of mastitogenic pathogens isolated from cows over these years also varied. Previously unknown or almost eradicated mastitogenic pathogens such as aß haemolytic Staphylococcus aureus which is thought to be of human origin, Streptococcus agalactiae and Enterococcus canis were responsible for numerous mastitis outbreaks seen in the test samples. Coagulase-negative staphylococci were the most frequently isolated bacteria in milk samples from both lactating and dry cows, followed by Staphylococcus aureus and Streptococcus agalactiae. Although Staphylococcus aureus remained the principal mastitogenic pathogen in South Africa, owing to its chronic nature and resultant economic losses, most cases of mastitis were caused by coagulase-negative staphylococci. This finding increases the importance of coagulase-negative staphylococci (formerly described as a minor pathogen) significantly. Isolations of Streptococcus agalactiae peaked between 2000 and 2005 and decreased again by 2007. Coagulase-negative staphylococcal isolates increased from 2002 and were still on the increase in 2007. Streptococcus agalactiae, Streptococcus uberis and Enterococcus canis were isolated more frequently from milk samples of lactating cows compared with dry cows, while Enterococcus faecalis was isolated more frequently from dry cow samples. <![CDATA[<b>Intramammary infection rate during the dry period in cows that received blanket dry cow therapy: Efficacy of 6 different dry-cow intra-mammary antimicrobial products</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1019-91282009000100004&lng=es&nrm=iso&tlng=es The objectives of this study were to compare the efficacy of 6 different dry-cow intra-mammary antimicrobial products for the treatment and prevention of mastitis during the dry period in a well-managed high producing Friesland dairy herd, and the influence of treatment on the somatic cell count (SCC) of cows during early lactation. One of 6 dry-cow intramammary antimicrobial products was randomly allocated to 162 cows due for drying off over a period of 14 months. All cows were sampled twice prior to drying off, and twice after calving for the determination of SCC and presence of microorganisms. The quarter prevalence of pathogens at drying off and post-calving, the overall quarter cure rate and the rate of new intramammary infections occurring during the dry period were determined. The overall quarter prevalence of intramammary infections (IMIs) at drying off was 29.78 % and after calving 22.22 %. There was a statistically significant difference (P < 0.05) between the prevalence of major and minor pathogens at drying off (7.87 % and 21.91 %) and at calving (4.47 % and 17.75 %). The most prevalent pathogens isolated at drying off (21.14 %) and at calving (16.98 %) were coagulase-negative staphylococci (CNS). The quarter cure rate during the dry period was 83.94 %. The cure rate for the major pathogens (98 %) was significantly better (P < 0.05) than that for minor pathogens (78.9 %). The overall quarter cure rate varied from 72.3 % to 93.9 % for the various products. The rate of new quarter infections during the dry period was 17.44 % with a significant difference (P < 0.05), between the prevalence of new quarter infections with major (4.32 %) and minor pathogens (13.12 %). CNS was the most prevalent pathogen causing new quarter infections (12.34 %) and the rate of new quarter infections variedfrom 13.4 % to 24.1 % for the various products. It is concluded that there is a difference in efficacy between antimicrobial intramammary dry-cow products in their ability to cure and prevent new IMIs during the dry period. Dry-cow products are mainly formulated for efficacy against Gram-positive cocci, while providing no or little protection against Gram-negative bacteria. Therapeutic levels may persist for only 14 to 28 days into the dry period and fail to protect the udder during the last trimester. Dry-cow therapy should, however, always form part of a holistic approach to the dry period which also considers cow factors, dry-cow management, microorganisms and the environment of the dry cow. <![CDATA[<b>A case-based, small-group cooperative learning course in preclinical veterinary science aimed at bridging basic science and clinical literacy</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1019-91282009000100005&lng=es&nrm=iso&tlng=es In 1999 a dedicated problem-based learning course was introduced into the lecture-based preclinical veterinary curriculum of the University of Pretoria. The Introduction to Clinical Studies Course combines traditional lectures, practical sessions, student self-learning and guided tutorials. The self-directed component of the course utilises case-based, small-group cooperative learning as an educational vehicle to link basic science with clinical medicine. The aim of this article is to describe the objectives and structure of the course and to report the results of the assessment of the students' perceptions on some aspects of the course. Students reacted very positively to the ability of the course to equip them with problem-solving skills. Students indicated positive perceptions about the workload of the course. There were, however, significantly lower scores for the clarity of the course objectives. Although the study guide for the course is very comprehensive, the practice regarding the objectives is still uncertain. It is imperative to set clear objectives in non-traditional, student-centred courses. The objectives have to be explained at the outset and reiterated throughout the course. Tutors should also communicate the rationale behind problem-based learning as a pedagogical method to the students. Further research is needed to verify the effectiveness of this course in bridging the gap between basic science and clinical literacy in veterinary science. Ongoing feedback and assessment of the management and content are important to refine this model for integratingbasic science with clinical literacy. <![CDATA[<b>Cardiovascular effects of lumbar epidural anaesthesia in isoflurane-anaesthetised pigs during surgical removal of the liver</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1019-91282009000100006&lng=es&nrm=iso&tlng=es In humans the combined administration of epidural anaesthesia and inhalation anaesthesia may result in cardiovascular instability associated with decreases in heart rate and blood pressure. Anaesthesia was induced with a combination of midazolam/ketamine in 18 female pigs with a mean body weight of 24.9 ± 5.9 kg scheduled for surgical removal of the liver. After tracheal intubation, anaesthesia was maintained on a circle rebreathing circuit with isoflurane. Epidural anaesthesia was administered with ropivacaine (AL-group, n = 8) at 0.2 ml/kg of a 7.5 mg/ml. solution to the anaesthetised animals. The A-group (n = 10) received isoflurane anaesthesia only. The vaporiser was set at 2.5 % for the A-group and 1.5 % for the AL-group. Heart rate, invasive systolic, diastolic , and mean arterial blood pressure were monitored. Comparisons were made between treatments and within treatments comparing variables during surgical preparation and abdominal surgery. Differences between treatments were not statistically significant (P &gt; 0.05) during surgical preparation or during abdominal surgery. For within treatment groups, the differences between surgical preparation and abdominal surgery were statistically significant (P < 0.05) for heart rate in the A-group, but not statistically significant (P &gt; 0.05) for the other variables. It is concluded that abdominal surgery maybe associated with statistically significant changes in heart rate in isoflurane-anaesthetised pigs and that the combined administration of epidural ropivacaine may prevent statistically significant changes in HR during abdominal surgery. <![CDATA[<b>Residue depletion of colistin in swine after intramuscular administration</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1019-91282009000100007&lng=es&nrm=iso&tlng=es A newly formulated colistin sulphate solution was prepared in a previous study as a potential agent for intramuscular injection and its effectiveness, toxicity and pharmacokinetics were investigated. In order to provide more information to establish scientific guidance for safe use of this preparation, its residue depletion in swine tissues following intramuscular administration was investigated in this experiment. Fifty healthy cross-bred piglets (13.3 ± 0.9 kg) were used in this study. Five animals were kept as untreated controls and the other 45 animals were intramuscularly injected with the colistin preparation at a dose of 2.5 mg/kg of body weight. From the treated piglets, 5 animals were randomly selected and sacrificed at different withdrawal times. Liver, kidney and muscle tissues were sampled to examine the colistin residue levels by microbiological assay. The results showed that the colistin residue in liver and muscle decreased quickly and could not be detected at 1 day after the final dosing. However, the residue depletion in the kidneys was much slower than that in other tissues and even a small quantity of drug could be detected at 14 days after withdrawal. Using the method recommended by the Committee for Veterinary Medical Products (CVMP), a withdrawal time of 10 days was established for the safe use of the newly formulated colistin sulphate solution. <![CDATA[<b>A serological survey of leptospirosis in cattle of rural communities in the province of KwaZulu-Natal, South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1019-91282009000100008&lng=es&nrm=iso&tlng=es A serological survey of leptospirosis in cattle originating from rural communities of the province of KwaZulu-Natal (KZN) in South Africa was carried out between March 2001 and December 2003. The survey was designed as a 2-stage survey, using the local diptank as the primary sampling point. In total, 2021 animals from 379 diptanks in 33 magisterial districts were sampled and tested with the microscopic agglutination test (MAT). The apparent prevalence at district level was adjusted for clustering and diagnostic test sensitivity and specificity and displayed in maps. The prevalence of leptospirosis in cattle originating from communal grazing areas of KZN was found to be 19.4 % with a 95 % confidence interval of 14.8-24.1 %. At district level the prevalence of leptospirosis varied from 0 to 63 % of cattle. Bovine leptospirosis was found to occur in communal grazing areas throughout the province with the exception of 2 districts. The southeastern regions showed a higher prevalence than other areas of the province; while in some of the northern and western districts alower prevalence was noted. Several serovars were detected by the MAT and although Leptospira interrogans serovar pomona occurred most frequently, serovars tarrasovi, bratislava, hardjo, canicola and icterohaemorrhagica were also frequently identified. The findings of the survey are discussed. <![CDATA[<b>Atlas of small animal dermatology</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1019-91282009000100009&lng=es&nrm=iso&tlng=es A serological survey of leptospirosis in cattle originating from rural communities of the province of KwaZulu-Natal (KZN) in South Africa was carried out between March 2001 and December 2003. The survey was designed as a 2-stage survey, using the local diptank as the primary sampling point. In total, 2021 animals from 379 diptanks in 33 magisterial districts were sampled and tested with the microscopic agglutination test (MAT). The apparent prevalence at district level was adjusted for clustering and diagnostic test sensitivity and specificity and displayed in maps. The prevalence of leptospirosis in cattle originating from communal grazing areas of KZN was found to be 19.4 % with a 95 % confidence interval of 14.8-24.1 %. At district level the prevalence of leptospirosis varied from 0 to 63 % of cattle. Bovine leptospirosis was found to occur in communal grazing areas throughout the province with the exception of 2 districts. The southeastern regions showed a higher prevalence than other areas of the province; while in some of the northern and western districts alower prevalence was noted. Several serovars were detected by the MAT and although Leptospira interrogans serovar pomona occurred most frequently, serovars tarrasovi, bratislava, hardjo, canicola and icterohaemorrhagica were also frequently identified. The findings of the survey are discussed. <![CDATA[<b>Putative <i>Aspergillus</i> <i>niger</i>-induced oxalate nephrosis in sheep</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1019-91282009000100010&lng=es&nrm=iso&tlng=es A sheep farmer provided a maize-based brewer's grain (mieliemaroek) and bales of Eragrostis curvula hay to ewes and their lambs, kept on zero-grazing in pens. The 'mieliemaroek' was visibly mouldy. After 14 days in the feedlot, clinical signs, including generalised weakness, ataxia of the hind limbs, tremors and recumbency, were noticed. Six ewes died within a period of 7 days. A post mortem examination was performed on 1 ewe. The carcass appeared to be cachectic with mild effusions into the body cavities; mild lung congestion and pallor of the kidneys were observed. Microscopical evaluation revealed nephrosis and birefringent oxalate crystals in the renal tubules when viewed under polarised light. A provisional diagnosis of oxalate nephrosis with subsequent kidney failure was made. Amongst other fungi, Aspergillus niger was isolated from 'mieliemaroek' samples submitted for fungal culture and identification. As A. niger is known to synthesise oxalates, a qualitative screen to detect oxalic acid in the mieliemaroek and purified A. niger isolates was performed using high-performance liquid chromatography (HPLC). Oxalic acid was detected, which supported a diagnosis of soluble oxalate-induced nephropathy. <![CDATA[<b><i>Post mortem</i></b><b> identification of <i>Kalicephalus colubri colubri</i> (Nematoda: Diaphanocephalidae) in a captive Mole snake <i>(Pseudaspis cana)</i> in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1019-91282009000100011&lng=es&nrm=iso&tlng=es Necropsy examination of a captive emaciated, dehydrated adult female Mole snake (Pseudaspis cana) in October 2007 revealed multiple cutaneous abscesses. Other findings included renal and hepatic atrophy, hepatic haemosiderosis, multifocal granulomatous hepatitis associated with acid-fast bacteria as well as pulmonary congestion and oedema. Large numbers of the nematode Kalicephalus colubri colubri were recovered from the oesophagus and stomach, representing the 1st reported case of K. colubri from a Mole snake in South Africa. The lesions caused by K. c. colubri were insignificant, but the presence of worms may have contributed to weight loss.