Development of a physiologic-based pharmacokinetic model for estimating sulfamethazine concentrations in swine and application to prediction of violative residues in edible tissues

OBJECTIVE: To develop a flow-limited, physiologic-based pharmacokinetic model for use in estimating concentrations of sulfamethazine after IV administration to swine. SAMPLE POPULATION: 4 published studies provided physiologic values for organ weights, blood flows, clearance, and tissue-to-blood partition coefficients, and 3 published studies provided data on plasma and other tissue compartments for model validation. PROCEDURE: For the parent compound, the model included compartments for blood, adipose, muscle, liver, and kidney tissue with an extra compartment representing the remaining carcass. Compartments for the N-acetyl metabolite included the liver and the remaining body. The model was created and optimized by use of computer software. Sensitivity analysis was completed to evaluate the importance of each constant on the whole model. The model was validated and used to estimate a withhold interval after an IV injection at a dose of 50 mg/kg. The withhold interval was compared to the interval estimated by the Food Animal Residue Avoidance Databank (FARAD). RESULTS: Specific tissue correlations for plasma, adipose, muscle, kidney, and liver tissue compartments were 0.93, 0.86, 0.99, 0.94, and 0.98, respectively. The model typically overpredicted concentrations at early time points but had excellent accuracy at later time points. The withhold interval estimated by use of the model was 120 hours, compared with 100 hours estimated by FARAD. CONCLUSIONS AND CLINICAL RELEVANCE: Use of this model enabled accurate prediction of sulfamethazine pharmacokinetics in swine and has applications for food safety and prediction of drug residues in edible tissues.     

Subtotal ostectomy of dorsal spinous processes performed in nine standing horses

OBJECTIVE: To describe and evaluate subtotal ostectomy of dorsal spinous processes (DSP) performed in standing horses. STUDY DESIGN: Retrospective study. SAMPLE POPULATION: Nine adult horses. METHODS: The diseased portions of the DSP were removed with the horses standing and sedated after infiltrating a local anesthetic agent around the affected DSP. Medical records of affected horses were reviewed to determine history, findings of physical and radiographic examination, surgical technique, postoperative complications, and outcome. RESULTS: Five horses had subtotal ostectomy of DSP because of osteomyelitis, and 4 because of impingement and/or fracture of DSP. Affected portions of DSP were removed safely and effectively, with no apparent discomfort to the horses; hemorrhage was minimal. CONCLUSIONS: Subtotal ostectomy of DSP can be performed safely in standing, conscious horses and the risks associated with general anesthesia are eliminated. Hemorrhage is minimal compared to that which occurs when the procedure is performed with horses anesthetized and in lateral recumbency. CLINICAL RELEVANCE: Access and visibility are better when subtotal ostectomy of the DSP is performed with the horse standing rather than anesthetized and in lateral recumbency. Performing subtotal ostectomy of diseased DSP with the horse standing avoids the expense and risks of general anesthesia.     

Comparative study of biochemical methods for the identification of Dichelobacter nodosus

The aim of this study was to compare four identification procedures to detect Dichelobacter nodosus and develop a rapid, simple and effective method to identify D. nodosus strains isolated from cases of ovine footrot. The four methods used were: (a) the classic guidelines set down by Holdeman et al. (1977) and Summanen et al. (1993) which are based on gas liquid chromatography (GLC) and different biochemical tests, this method was considered as landmark; (b) Baron and Citron's flowchart for the rapid identification of Gram-negative rod-shaped anaerobes (1997); (c) the API rapid 32 A system (bio Mérieux), and (d) Mast ID Anaerobe ID Ring (MID8) (Mast Diagnostics). None of the four methods used allowed us to correctly identify the D. nodosus strains (neither the strains isolated from cases of ovine footrot nor those originating from type collection). Because of the difficulties encountered in obtaining a correct identification of D. nodosus, we propose a simple, rapid and effective way to achieve this task. Our flowchart will provide the means to identify this microorganism in any laboratory of general microbiology without having to use any specialised equipment.     

Effectiveness of different adjuvants in stimulating Dichelobacter nodosus antibody in sheep vaccinated against ovine footrot

This research consists of an evaluation of the effectiveness of different substances administered as adjuvants in the stimulation of humoral immune response induced by the vaccine composed of strains A1, A2 and C of Dichelobacter nodosus. To do this, a total of 120 Merino sheep were vaccinated and revaccinated. These sheep were selected from a farm located in the region of Extremadura (Spain), and they were divided into 12 groups of 10 animals each. An additional group with 10 sheep was used as control. The immune response (titre of antibodies) was determined by agglutination tests and ELISA. The most pronounced immune response was obtained by the use of Freund's incomplete adjuvant and aluminium hydroxide as adjuvants.     

Prevalence of fetal resorption in stray dogs in Yucatan, Mexico

OBJECTIVES: To determine the prevalence of fetal resorption in 77 pregnant bitches and its association with the age, size and body condition score of the bitch and to determine the frequency of transuterine migration of embryos. METHODS: The number and position of embryos or fetuses and placental zones were registered postmortem. The prevalence of fetal losses was determined by comparing the number of corpora lutea with the number of embryos or fetuses in each bitch. The prevalence of transuterine migration of embryos was determined by correlating the number of fetuses in each horn and the number of corpora lutea in the ipsilateral ovary. RESULTS: Fetal resorption zones were demonstrated in 42.9 per cent of the bitches. However, pregnancy continued in 84.9 per cent of cases. Of the fetal losses, 25.9 per cent were determined by counting the number of corpora lutea and viable embryos or fetuses. Young bitches tended to have a higher probability of fetal resorption than adult bitches (P<0.06). The presence of fetal resorption zones was not associated with size or body condition. Transuterine migration of embryos had occurred in 15.8 per cent of the bitches. CLINICAL SIGNIFICANCE: This study demonstrated that embryo resorption is a normal event in the bitches, with a higher prevalence than previously thought.     

American trypanosomiasis infection in fattening pigs from the south-east of Mexico

American Trypanosomiasis (AT) is an infectious parasitic disease produced by the protozoa Trypanosoma cruzi (T. cruzi). Infection is acquired by vectorial via but can also be transmitted congenitally, by ingestion of an infected host, by transfusion with contaminated blood or transplant of organs from an infected donor. Currently, AT is widely distributed from the South of the United States to South America. In Mexico, the presence of the parasite has been reported throughout the country where several reservoirs such as dogs, opossums, rats and cats have been identified. Yucatan is in the south-east of Mexico where AT is endemic and has been reported since 1940s. There is little information about the role of pigs as reservoirs of T. cruzi. The frequency of specific antibodies against T. cruzi was determined in fattening pigs from Yucatan, Mexico. After sampling in the 3 main areas of pig production in the state, IgG ELISA and Western blot were performed to identify seropositive cases. Association of farm size, farm area and production system with infected pigs was evaluated. From 273 sampled pigs, 5.4% (n = 15) positive cases were found. No association with evaluated factors and infected pigs was found. Pigs are also reservoirs of T. cruzi in the studied area. These findings are considered important to improve vectorial control in the area in order to avoid the parasite infection in animal populations destined for human consumption and avoid further transmission to humans.