Experimental Hemorrhagic Septicemia: Gross and Microscopic Lesions Resulting from Acute Infections and from Endotoxin Administration

Gross and microscopic lesions observed in bovine and porcine hemorrhagic septicemia, and in bovine Pasteurella multocida endotoxemia are described. Widely distributed hemorrhages, edema, and general hyperemia were the most obvious tissue changes observed in the infected calves. Pneumonia was a constant lesion. Aerosol exposure produced a multiple focal fibrinosuppurative pneumonia, while intranasal and intramuscular inoculation resulted in generalized interstitial pneumonia. A slight lymphadenitis and degenerative changes in hepatic and renal parenchymal cells were also observed.

The predominant lesions observed in infected pigs were a diffuse, extensive, fibrinous pneumonia and fibrinous polyserositis. Edema and general hyperemia were observed, but the widespread hemorrhages which occurred in the calves were not present. Acute lymphadenitis and renal tubule vacuolar degeneration were observed. A slight amount of cloudy swelling and focal areas of necrosis were found in the liver.

Lesions in a calf that died following administration of Past. multocida endotoxin were widely distributed hemorrhages, edema, and general hyperemia. These lesions were especially evident in the lungs, and indicated widespread vascular alteration.

     

Mechanical comparison of an interlocking nail locked with conventional bolts to extended bolts connected with a type-IA external skeletal fixator in a tibial fracture model

OBJECTIVE: To compare the structural properties of interlocking nails (ILNs) locked with bolts (ILNb) to ILN locked with extended bolts connected with a type-IA external skeletal fixator (ILN-ESF) in a fracture gap model. STUDY DESIGN: Experimental study. SAMPLE POPULATION: Synthetic tibial bone substitutes. METHODS: Custom-made synthetic tibial bone substitutes were implanted with standard ILNs locked with either bolts or extended bolts connected to an external skeletal fixation (ESF). Constructs were tested in torsion, bending, and axial compression (n=4/testing mode). Data, consisting of construct compliance and associated deformation, were compared using t-tests. RESULTS: The ILN-ESF construct compliance and deformation were significantly less than those of the ILNb construct in torsion, bending, and compression (P<.001). Slack was present in the ILNb construct under torsion and bending, but not in the ILN-ESF construct, regardless of testing mode. CONCLUSIONS: Substitution of locking bolts with extended bolts connected to an ESF significantly reduced the construct compliance and overall deformation in torsion, bending, and compression. Furthermore, the inherent slack of the ILNb was eliminated by the use of an ESF in torsion and bending. CLINICAL RELEVANCE: The improvement in structural properties of the ILN-ESF constructs could diminish interfragmentary motion at the fracture site and potentially improve bone healing.     

Computed tomography of the lungs of Indian pythons (Python molurus)

OBJECTIVE: To evaluate the use of computed tomography (CT) for detection of pneumonia in snakes. ANIMALS: 8 clinically normal Indian pythons (Python molurus) and 5 pythons with evidence of respiratory tract disease. PROCEDURES: Preliminary examinations (clinical examination, conventional radiography, and microbiologic examination of a transtracheal wash sample) were performed. The lungs of each snake were then examined by use of CT performed in accordance with a standardized protocol. Structures of the lungs were assessed, and thickness and attenuation of the parenchyma were determined. RESULTS: It was possible to assess lung parenchyma in all pythons. Mean +/- SD attenuation in healthy pythons was -744.4 +/- 47.1 Hounsfield units. Significant differences were not evident between the right and left lungs or among measurement areas within a lung. In all Indian pythons with clinical signs of dyspnea and microbiologic detection of pathogens, hyperattenuation of the alveolar tissue was evident. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of the results revealed the benefit of CT for use in the diagnosis of pneumonia in snakes. A standardized protocol and reference values were established as a basis for CT assessment of the lungs of snakes.     

The bioavailability and disposition kinetics of genistein in cats

The absorption and disposition kinetics of the soy isoflavone genistein were determined in cats (n = 6). An oral dose of 100 mg/kg was administered, which has previously been demonstrated to be the minimum oral estrogenic dose, and was administered intravenously at a dose of 20 mg/kg, being the largest practical dose that could be safely administered. Plasma free, and total (conjugated + free) genistein concentrations were determined by HPLC following organic extraction. Noncompartmental analysis revealed a half-life of 21.67 +/- 7.9 h (free) and 9.95 +/- 2.7 h (conjugated), volume of distribution 31.94 +/- 10.38 L/kg (free) and 11.82 +/- 3.96 L/kg (conjugated) following intravenous administration. Following oral administration the half-lives were determined to be 17 +/- 4.8 h (free) and 8.56 +/- 4.65 h (conjugated), with tmax = 4.4 +/- 0.6 h (free) and 4.42 +/- 0.99 h (conjugated), and Cmax = 0.276 +/- 0.1 microg/mL (free) and 6.24 +/- 6.58 microg/mL (conjugated). Oral bioavailabilities were 1.379 +/- 0.9% (free) and 29.85 +/- 22.61% (conjugated). The ratio of total:free genistein ranged from 25.9 to 5.5. Poor oral absorption and efficient conjugation explain the low bioavailability of free genistein. Accumulation of genistein in peripheral lipophilic compartments may occur.     

Salmonella enterica infections in Spanish swine fattening units

The present study is the first conducted in Spain to estimate the bacteriological herd prevalence of Salmonella enterica in fattening units and to describe the Salmonella serovar diversity on these farms using a sample representative of the entire swine population. For this purpose, 10 faecal samples were collected from 10 different pens containing pigs close to market weight in a total of 232 fattening units. Total sample size was proportionally distributed according to the fattener census in each of the regions of the country and all the samples were examined by culture of 25 g of faecal material. One hundred (43.1%) farms had at least one Salmonella-positive sample (95% CI: 37-49.1%). Salmonella enterica was detected in 290 (12.5%) pooled faecal floor samples (95% CI: 11.2-13.8%). The apparent herd prevalence of salmonellosis was similar among multi-site, finishing and farrow to finish farms. Overall, 24 different serovars were identified, with S. Typhimurium, S. Rissen and S. Derby being the most common both at herd and sample level. Results of phage typing were available for the 91 isolates of S. Typhimurium. A total number of 10 different phage types were identified, with DT 193 being the most frequent. Phage types DT 104, DT 104b and DT U302, which have been associated with several multi-resistant patterns, accounted for 23% and 29% of the Typhimurium total isolates or Typhimurium infected farms respectively.     

Development and validation of the maximal electro-shock seizure model in dogs

The development and validation of the maximal electro-shock (MES) model using phenobarbital (Pb) as the positive control is described. This approach builds on previous work in rodent model systems, and has been adapted to dogs as a tool for pharmaceutical dose selection. Dogs, like rodents, exhibit generalized convulsions which manifest as progressive clinical signs in a dose (electrical current) dependent fashion. At the limit (300 mA, 200 msec) animals underwent clonic-tonic convulsions consistent with complete generalized (Grand Mal) seizures with a grade 3 clinical score (CS) and a menace response time of 98.5 +/- 24.4 sec (n = 8). Pretreatment of animals with Pb at 3, 10, and 30 mg/kg, in a 4-by-4 complete block crossover design (Latin-Square), resulted in a dose-dependant reduction in CS and menace response time. Estimates of plasma Pb concentration taken prior to MES induction showed a similar dose-dependent reduction in CS and menace response time with concentration. Using a cumulative logistic regression model, a predicted 50% probability of a CS = 1 was approximately 11.4 mg/kg. In addition, plasma Pb concentrations predicted a 50% probability of a CS = 1 occurs at plasma Pb concentration of approximately 16.0 mug/mL. Combined these data suggest that MES is a useful model for evaluating generalized convulsions in canines and may provide a tool for dose selection of novel pharmaceutical compounds.     

Spatial analysis of the exposure of dogs in rural north-coastal California to vectorborne pathogens

Between 0 and 50 per cent of the dogs in eight rural villages in far northern California with a high risk of tickborne diseases were seropositive for Anaplasma phagocytophilum and Bartonella vinsonii subspecies berkhoffii, and between 0 and 10 per cent were seropositive for Borrelia burgdorferi. The odds ratio for the co-exposure of individual dogs to B vinsonii berkhoffii and A phagocytophilum was 18.2. None of the diseases was associated with the sex of the dogs, whether they slept out of doors, or whether tick-preventive measures were taken. When the villages were assessed for landscape risk factors, a particularly high seroprevalence for B vinsonii berkhoffii and A phagocytophilum was observed in a village at a relatively high altitude and greater distance from the Pacific coast, and montane hardwood conifer woodland was most associated with a high seroprevalence for these two pathogens.     

Immunopathology of <Emphasis Type="Italic">Dirofilaria immitis</Emphasis> Infection

Heartworm disease caused by Dirofilaria immitis affects canine and feline hosts, with infections occasionally being reported in humans. Studies have shown that both dirofilarial antigens and those derived from its bacterial endosymbiont Wolbachia, interact with the host organism during canine, feline and human infections and participate in the development of the pathology and in the regulation of the host’s immune response. Both innate and acquired immune responses are observed and the development of the acquired response may depend on the host and, or on its parasitological status. This review aims at illustrating current research on the role of both D. immitis and Wolbachia, in the immunology and immunopathology of dirofilariosis.