No evidence for avoidance of black rat scent by the presumably less competitive Natal multimammate mouse in a choice experiment

In Africa, indigenous multimammate mice (Mastomys natalensis) only appear to live commensally in houses when invasive black rats (Rattus rattus) are absent, yet little is known about the underlying mechanism. Avoidance through smell may cause the absence of M. natalensis from areas occupied by R. rattus, but this hypothesis has not yet been tested. We conducted a Y-maze choice experiment where 15 M. natalensis were offered a choice between corridors containing conspecific scent, R. rattus scent and a control scent. Residence time in the R. rattus corridor was greater than that in the control corridor but equal to that in the M. natalensis corridor, suggesting that multimammate mice do not actively avoid the scent of their invasive competitor.     

New histochemical and ultrastructural observations on normal bovine tonsils.

Samples of normal bovine palatine tonsils were examined by light and electron microscopy. Like human tonsils, they were composed of crypts, subepithelial areas, follicles, and T-dependent zones, but their well-developed capsule subdivided the lymphoid tissue by connective septa. B cells formed the major lymphoid component. The follicles and T-dependent zones had morphological and histochemical features typical of peripheral lymph organs. Follicular dendritic cells were isolated and shown to be similar to human follicular dendritic cells.     

Characteristics of Peri-urban Dairy Herds of Bobo-Dioulasso (Burkina Faso)

Peri-urban dairy cattle farms within 50 km of Bobo-Dioulasso were studied to assess herd type, disease incidence, management, feeding and breeding strategy. Out of 417 cattle farmers, 42% had dairy objectives and were studied. Among these peri-urban dairy farmers, 60% were settled, 36% semi-settled, and 4% transhumant. In total, they held 4558 dairy cows, of which 32% lactated during the study. The prevalence of mastitis (55%) increased (p<0.05) with herd size. Advanced strategies for supplementary feeding and breeding were most frequent in small herds (<30 cattle). None of the large herds (>60 cattle) had advanced breeding strategies. Bulls and cows were culled at younger ages in herds with better breeding strategy. Overall, this resulted in higher individual milk offtake in small herds (2.46 L/day) compared with large herds (1.25 L/day). Pure breeds were rarely used, and the presence of Bos taurus baoulé naturally selected for trypanotolerance was low. The prevalence of trypanosomosis (40%) in herds dominated by Bos indicus zebu and Méré (Zebu x Baoulé) is an argument for maintenance of biodiversity and selection of Baoulé for milk production.     

Evaluation of serum 17-hydroxyprogesterone concentration after administration of ACTH in dogs with hyperadrenocorticism

OBJECTIVE: To evaluate serum 17-hydroxyprogesterone (17-OHP) concentration measurement after administration of ACTH for use in the diagnosis of hyperadrenocorticism in dogs. DESIGN: Prospective study. ANIMALS: 110 dogs. PROCEDURE: Serum 17-OHP concentrations were measured before and after ACTH stimulation in 53 healthy dogs to establish reference values for this study. Affected dogs had pituitary-dependent (n = 40) or adrenal tumor-associated (12) hyperadrenocorticism or potentially had atypical hyperadrenocorticism (5; diagnosis confirmed in 1 dog). In affected dogs, frequency interval and borderline and abnormal serum 17-OHP concentrations after ACTH stimulation were determined. Serum cortisol concentrations were assessed via low-dose dexamethasone suppression and ACTH stimulation tests. RESULTS: In healthy dogs, serum 17-OHP concentration frequency intervals were grouped by sex and reproductive status (defined as < 95th percentile). Frequency intervals of serum 17-OHP concentrations after ACTH stimulation were < 77, < 2.0, < 3.2, and < 3.4 ng/mL (< 23.3, < 6.1, < 9.7, and < 10.3 nmol/L) for sexually intact and neutered females and sexually intact and neutered males, respectively. In 53 dogs with confirmed hyperadrenocorticism, serum cortisol concentrations after ACTH stimulation and 8 hours after administration of dexamethasone and serum 17-OHP concentrations after ACTH stimulation were considered borderline or abnormal in 79%, 93%, and 69% of dogs, respectively. Two of 5 dogs considered to have atypical hyperadrenocorticism had abnormal serum 17-OHP concentrations after ACTH stimulation. CONCLUSIONS AND CLINICAL RELEVANCE: Serum 17-OHP concentration measurement after ACTH stimulation may be useful in the diagnosis of hyperadrenocorticism in dogs when other test results are equivocal.     

Pharmacokinetics of methylprednisolone acetate after intra-articular administration and subsequent suppression of endogenous hydrocortisone secretion in exercising horses

Objective-To determine the pharmacokinetics of methylprednisolone (MP) and the relationship between MP and hydrocortisone (HYD) concentrations in plasma and urine after intra-articular (IA) administration of 100 or 200 mg of MP acetate (MPA) to horses. Animals-Five 3-year-old Thoroughbred mares. Procedures-Horses exercised on a treadmill 3 times/wk during the study. Horses received 100 mg of MPA IA, then 8 weeks later received 200 mg of MPA IA. Plasma and urine samples were obtained at various times for 8 weeks after horses received each dose of MPA; concentrations of MP and HYD were determined. Pharmacokinetic-pharmacodynamic estimates for noncompartmental and compartmental parameters were determined. Results-Maximum concentration of MP in plasma was similar for each MPA dose; concentrations remained greater than the lower limit of quantitation for 18 and 7 days after IA administration of 200 and 100 mg of MPA, respectively. Maximum concentration and area under the observed concentration-time curve for MP in urine were significantly higher (approximately 10-and 17-fold, respectively) after administration of 200 versus 100 mg of MPA. Hydrocortisone concentration was below quantifiable limits for ≥ 48 hours in plasma and urine of all horses after administration of each MPA dose. Conclusions and Clinical Relevance-Pharmacokinetics of MP may differ among IA MPA dosing protocols, and MP may be detected in plasma and urine for a longer time than previously reported. This information may aid veterinarians treating sport horses. Further research is warranted to determine whether plasma HYD concentration can aid identification of horses that received exogenous glucocorticoids.     

Pathological and aetiological studies of multifocal interstitial nephritis in wasted pigs at slaughter

Multifocal interstitial nephritis in pigs has been associated with several infectious agents. The objective of the present study was to investigate several different potential infectious agents associated with "white-spotted" kidneys in pigs suffering from wasting at slaughter (aged 6-8 months). Twenty-nine case kidneys (with a "white-spotted" gross appearance) classified into 3 macroscopic lesional grades, and 15 control kidneys (lacking gross lesions), were obtained from a pig abattoir. Laboratory analyses to detect potential associations with the aforementioned pathological condition with Leptospira spp., porcine circovirus type 2 (PCV2), porcine parvovirus (PPV), porcine reproductive and respiratory syndrome virus (PRRSV), and bacteria, were carried out. Microscopically, interstitial nephritis with a lymphofollicular inflammatory pattern (follicular nephritis) was observed in both case and control kidneys, with a higher frequency seen in the former ones. No leptospires were identified, although antibodies to the Pomona and Bratislava serovars were detected. Some pyogenic bacteria were also isolated from both case and control kidneys. PCV2 nucleic acid was only detected in 1 case kidney. PRRSV antigen was not found in any tested sample. Some pigs were tested positive for PPV by serology. Apparently, none of the studied agents were specifically associated as being the potential cause of the renal lesions in the studied wasted pigs. The fact that these chronic lesions may have been the consequence of a previous infection with one of these studied microorganisms, or more, and eventually with other non-tested infectious agents during the growing-finishing period, cannot be ruled out.     

Piroplasma infection in dogs in northern Spain

Babesiosis is a world-wide zoonosis caused by tick-borne hematozoan parasites of the genus Babesia. Canine Babesidae have historically been classified as "large Babesia" (Babesia canis) and "small Babesia" (Babesia gibsoni) based on the size of their intraerythrocytic forms. Genetic sequencing technology using the polymerase chain reaction (PCR) has allowed further subdivision. B. gibsoni has three strains: "Asia", "California" and a recently identified small babesial-like parasite, Theileria annae. This newly recognised piroplasm appears to be hyperendemic in northwest Spain. In order to provide some insight into the situation, all the cases diagnosed in our laboratory (NW of Spain) during 2003 were evaluated. Our study (62 samples) shows the existence of a piroplasm morphologically different from B. canis and similar to B. gibsoni, which is genetically related to T. annae. Severe regenerative anemia and thrombocytopenia are almost constant characteristics of infection with T. annae in dogs. In many cases azotemia is found. Abnormally high serum concentrations of urea and creatinin, together with elevated concentrations of inorganic phosphorus, hypoalbuminemia, hypercholesterolemia, proteinuria, high protein/creatinin and presence of hyaline and granular casts in the microscopic examination of urine sediment suggest a glomerular component to the disease. We conclude that observational research and clinical trials should be conducted in order to improve our understanding of this emerging disease in order to provide some insight into the best therapeutic practices.