In vitro antibacterial activity of enrofloxacin and ciprofloxacin in combination against Escherichia coli and staphylococcal clinical isolates from dogs.

The objective of the study was to determine the in vitro interaction between enrofloxacin and ciprofloxacin against Escherichia coli and staphylococcal isolates from dogs. The microdilution checkerboard assay was used to determine the interaction of the drugs against 50 E. coli and 50 beta-haemolytic staphylococcal clinical isolates. The checkerboard assay revealed that the activity of enrofloxacin and ciprofloxacin was additive against E. coli and staphylococcal clinical isolates. It was concluded that for bacterial species against which ciprofloxacin is more potent than enrofloxacin, the in vivo transformation of enrofloxacin to ciprofloxacin may enhance the efficacy of enrofloxacin, if additivity of the drugs is confirmed in vivo.

Evaluation of the effectiveness of following up laboratory reports of elevated blood leads in adults.

The usefulness of a statewide laboratory-based blood lead surveillance system to initiate workplace enforcement inspections was studied. In particular, the effectiveness of inspection of companies in which at least one worker had a blood lead level (BLL) 30-39 microg/dL but no greater than 39 microg/dL was considered. The surveillance system identified all individuals who had been tested for blood lead. Adults with BLLs > or =30 microg/dL were interviewed. Companies where lead exposures occurred were identified and enforcement inspections performed there. Companies were grouped into four categories: one or more employees with BLL > or =50 microg/dL; one or more employees with highest BLL of 40-49 microg/dL; one or more employees with highest BLL of 30-39 microg/dL; and companies that used lead but from which no blood lead reports were received. The number of citations and amounts of penalties, and BLLs before and after, were compared among the three blood lead groups and with a control group of no lead-using companies. A cost-benefit analysis was performed. Citations and penalties did not differ among the three blood lead groups but were markedly increased compared with the lead using but no blood lead group. Violations of specific lead standard components were similar among the three blood lead groups. Blood lead companies had increased citations and penalties as compared with nonusing lead control companies. No significant decrease in blood leads was seen postinspection. Total cost to identify lead-exposed workers at problem work sites was $125 ($53-$459) per lead-exposed worker. Followup of companies identified through the surveillance system was an effective method to target workplace inspections. It is recommended that routine inspection be instituted for all companies in which an employee is reported to have a blood lead of 30 microg/dL or greater.

Effects of pubic symphysiodesis in dysplastic puppies.

OBJECTIVE: To determine the long-term effects of juvenile pubic symphysiodesis (JPS) in dysplastic puppies. STUDY DESIGN: Prospective, randomized, clinical trial. ANIMALS: Seven dysplastic Chesapeake Bay retrievers and 2 beagle-crosses (BX1 and 2). METHODS: Five puppies had JPS performed with electrocauterization at 12, 16, 20, 22, and 24 weeks of age, respectively. Two puppies served as controls. BX1 and BX2 were used to obtain biopsies of the symphysis. Hips were evaluated for: pelvic development (transverse computerized tomography for acetabular angle [AA] and dorsal acetabular rim angle [DARA]); laxity [hip extended and stress radiography [distraction index (DI)]); Ortolani maneuver with reduction angles; acetabular coverage (Norberg angles); and function (coxofemoral range of motion, hip pain, and gait analysis by force-plate technique at 44 and 137 weeks of age). RESULTS: The pubis fused prematurely in every puppy that was operated on with the JPS technique. Greater acetabular responses were related to younger ages at surgery. The final mean AA in dogs that had JPS was 25 degrees greater than preoperative values; 40% increased over control. The DARA final mean was 10 degrees, 52% less than preoperative values and 46% less than control. The final mean DI in dogs having JPS was 0.28, 47% improved over preoperative values and 58% better than control. Mean pelvic dimensions in dogs that had JPS were 18% less than control. Gait analyses were normal for all dogs at 137 weeks. No urinary or bowel complications occurred. CONCLUSIONS: Significant ventrolateral acetabular rotation, increased hip coverage, diminished hip laxity, normal pain-free gait, and insignificantly reduced pelvic size occurred after JPS. CLINICAL SIGNIFICANCE: Dysplastic hips in young dogs were significantly improved by JPS.

Canine pubic symphysiodesis: investigation of electrocautery dose response by histologic examination and temperature measurement.

OBJECTIVES: To determine thermal necrosis zone and the maximal temperature achieved with various electrocautery doses applied to the pubic symphysis of immature dogs, and to establish the minimal electrocautery dose needed to affect thermal necrosis of the germinal chondrocytes of the immature canine pubis. STUDY DESIGN: A randomized, controlled, prospective study. ANIMALS: Twelve puppies, 15 to 17 weeks of age. METHODS: Each treated puppy was randomly selected to receive 3 of 33 possible doses of electrical current applied at uniform intervals along the pelvic symphysis. Three treatment sites were sham-operated controls. All treatment zones were biopsied 7 days after application of electrocautery. Confocal laser microscopy with calcein green and ethidium homodimer red stains were used to determine cell type and viability within treatment and control zones. The physeal diameter and thermal necrosis zone were measured. Thermal necrosis zone and dose, and temperature and dose were compared using regression analysis. Prediction equation analysis was used to establish dose recommendations. RESULTS: Doses of 40 W produced a highly significant linear relationship (R(2) =.88, P <.01) with thermal necrosis zone, and a significant linear relationship (R(2) =.76, P <.02) with maximal temperature. CONCLUSIONS: The thermal necrosis zone within the pelvic symphysis and maximal temperature achieved can be reliably predicted using electrocautery doses of 40 W. For application of electrocautery to induce pubic symphysiodesis, doses should be chosen based on measured or estimated physeal size. Using prediction equation analysis, the surgeon can plan mean thermal necrosis zone with acceptable variance. CLINICAL RELEVANCE: Unipolar needle electrocautery can be used to reliably achieve symphyseal necrosis. Prediction equation analysis can be used to determine 40-W doses.

Comparison of two palpation, four radiographic and three ultrasound methods for early detection of mild to moderate canine hip dysplasia.

Hip joint laxity was evaluated in Golden Retriever (n = 60), Labrador Retriever (n = 23), and Labrador/Golden Retriever mix (n = 24) puppies. Ortolani and Bardens maneuvers, four radiographic measurement indices and three dynamic ultrasonographic measurements were used. Each puppy was evaluated twice; at 6.5 to 9 and 43 to 79 weeks of age. These nine methods were compared for accuracy in predicting the development of canine hip dysplasia with or without degenerative joint disease by a median age of 16 months. The Bardens maneuver was a significant predictor of canine hip dysplasia/+/-degenerative joint disease for Golden Retriever puppies, however, it was not a reliable predictor for the other two breeds. Norberg angle measurements taken with femurs in a neutral position with hips distracted (PennHip position) was a significant predictor of degenerative joint disease in two breeds, but not in Golden Retriever puppies. Ultrasound measurement was a reliable predictor of hip canine hip dysplasia/+/-degenerative joint disease for Labrador/Golden Retriever mix puppies, but was not reliable for the other two breeds. Palpation, radiographic, and ultrasonographic methods of evaluating hip joint laxity in puppies at 6.5 to 9 weeks of age were not consistently reliable for all three breeds in predicting hip dysplasia with or without degenerative joint disease at one year of age. A strong association was found between Norberg angle and degenerative joint disease occurrence, as well as between distraction index (PennHip) and degenerative joint disease occurrence when measured at 52 to 79 weeks of age, but not when measured at 6.5 to 9 weeks of age in these breeds. These results emphasize the difficulty of early detection of mild hip dysplasia in the dog.

Pharmacokinetics of ceftazidime in dogs following subcutaneous administration and continuous infusion and the association with in vitro susceptibility of Pseudomonas aeruginosa.

OBJECTIVE: To determine the pharmacokinetics of ceftazidime following subcutaneous administration and continuous IV infusion to healthy dogs and to determine the minimum inhibitory concentration (MIC) of ceftazidime for clinical isolates of Pseudomonas aeruginosa. ANIMALS: 10 healthy adult dogs. PROCEDURE: MIC of ceftazidime for 101 clinical isolates of P aeruginosa was determined in vitro. Serum concentrations of ceftazidime were determined following subcutaneous administration of ceftazidime (30 mg/kg of body weight) to 5 dogs and continuous IV infusion of ceftazidime (loading dose, 4.4 mg/kg; infusion rate, 4.1 mg/kg/h) for 36 hours to 5 dogs. RESULTS: The MIC of ceftazidime for P aeruginosa was < or = 8 microg/ml; all isolates were considered susceptible. Following SC administration of ceftazidime, mean beta disappearance half-life was 0.8 hours, and mean serum ceftazidime concentration exceeded the MIC for P aeruginosa for only 4.3 hours. Two dogs had gastrointestinal tract effects. Mean serum ceftazidime concentration exceeded 16 microg/ml during continuous IV infusion. None of the dogs developed adverse effects. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of ceftazidime subcutaneously (30 mg/kg, q 4 h) or as a constant IV infusion (loading dose, 4.4 mg/kg; rate, 4.1 mg/kg/h) would maintain serum ceftazidime concentrations above the MIC determined for 101 clinical isolates of P aeruginosa. Use of these dosages may be appropriate for treatment of dogs with infections caused by P aeruginosa.

Effects of Pasteurella haemolytica leukotoxin and lipopolysaccharide on histamine, prostanoid, and leukotriene release by bovine lung parenchyma in vitro.

OBJECTIVE: To identify the effect of Pasteurella haemolytica lipopolysaccharide (LPS) and leukotoxin (LKT) on spontaneous and calcium ionophore-induced histamine and inflammatory mediator release from isolated bovine lung parenchyma. SAMPLE POPULATION: Lungs from 8 healthy cattle. PROCEDURE: Isolated bovine lung parenchyma was incubated in vitro for 2 hours with LKT or LPS, and spontaneous and induced release of inflammatory mediators was determined. RESULTS: LKT and LPS increased spontaneous release of histamine and leukotriene B4. In addition, incubation with LPS increased spontaneous release of prostaglandin E2. Moreover, a differential effect of the 2 toxins on calcium ionophore-induced inflammatory mediator release was observed. LKT specifically primed isolated lung parenchyma to release leukotriene B4 and thromboxane B2 in response to calcium ionophore, whereas LPS did not alter the profile of prostanoids released by bovine lung tissue exposed to calcium ionophore. CONCLUSIONS: Pasteurella haemolytica toxins have a direct effect on bovine lung parenchyma, causing release of inflammatory mediators, which contribute to response to infection. Furthermore, bacterial toxins (LKT in this study) may sensitize tissues to the effects of other irritant stimuli, amplifying the inflammatory response.