Estimating the incubation period of raccoon rabies: a time-space clustering approach

We used a time-space clustering approach to estimate the incubation period of raccoon rabies in the wild using data from the 1999-2001 invasion of raccoon rabies into eastern Ontario from northern New York State. The time differences and geographical distances between all possible pairs of rabies cases were computed, classified and assembled into a time-space matrix. The rows of that matrix represented differences in cases in weeks and the columns represent distances between cases in kilometers and the values in the cells of the matrix represent the counts of cases at specific time and distance intervals. There was a significant cluster of pairs 5 weeks apart with apparent harmonics at additional 5-week intervals. These results are explained by assuming the incubation period of raccoon rabies had a mode of 5 weeks. The time clusters appeared consistently at distance intervals of 5 km. We discuss the possibility that the spatial intervals were influenced by the 5 km radius of the point infection control depopulation process used in 1999 and the 10-15 km radial areas used in 2000. With the practical limits of those radii, there was an intensive effort to eliminate raccoons. Our procedure is easy to implement and provides an estimate of the shape of the distribution of incubation periods for raccoon rabies.     

Experimental evaluation of urinary bladder marsupialization in male goats

OBJECTIVE: To evaluate the outcome of urinary bladder marsupialization in male goats. STUDY DESIGN: Prospective, experimental study. ANIMALS: Six healthy mixed-breed male goats. METHODS: After experimentally induced urethral obstruction, 6 male goats had urinary bladder marsupialization. Renal ultrasonography, complete blood count, and serum biochemical analysis were evaluated preoperatively (day 0), at 7 postoperative days, and then at 30-day intervals until 180 days. Stomal diameter was recorded immediately postoperatively and at each postoperative interval. Necropsy examination was performed on day 180 or when stomal stricture or death occurred. RESULTS: Stomal stricture occurred in 1 goat at 120 days. Another goat was found dead at 150 days; severe, suppurative cystitis was identified on necropsy. All goats had mild urine scald dermatitis. Serum biochemical values remained within normal limits, but significant decreases in white blood cell count, serum creatinine concentration, and stomal diameter occurred. At necropsy, all bladders were tubular in shape. Histological evidence of chronic suppurative cystitis and chronic, mild lymphoplasmacytic pyelitis occurred in all goats. Bacterial culture of renal tissue yielded growth in 3 goats, and bladder mucosal swabs yielded bacterial growth in all goats. CONCLUSIONS: Although clinical signs of ascending urinary tract infection were not observed in goats with patent stomata, urinary bladder marsupialization may result in ascending urinary tract inflammation or infection. CLINICAL RELEVANCE: Based on our results, urinary bladder marsupialization should be recommended with caution as the primary method for management of urinary tract obstruction in clinical cases.     

Seroprevalence of antibodies against Bartonella species and evaluation of risk factors and clinical signs associated with seropositivity in dogs

OBJECTIVE: To determine the seroprevalence of antibodies against Bartonella spp in a population of sick dogs from northern California and identify potential risk factors and clinical signs associated with seropositivity. SAMPLE POPULATION: Sera from 3,417 dogs. PROCEDURE: Via an ELISA, sera were analyzed for antibodies against Bartonella vinsonii subsp berkhoffii, Bartonella clarridgeiae, and Bartonella henselae; test results were used to classify dogs as seropositive (mean optical density value > or = 0.350 for B henselae or > or = 0.300 for B clarridgeiae or B vinsonii subsp berkhoffi) or seronegative. Overall, 305 dogs (102 seropositive and 203 seronegative dogs) were included in a matched case-control study. RESULTS: 102 of 3,417 (2.99%) dogs were seropositive for > or = 1 species of Bartonella. Of these, 36 (35.3%) had antibodies against B henselae only, 34 (33.3%) had antibodies against B clarridgeiae only, 2 (2.0%) had antibodies against B vinsonii subsp berkhoffii only, and 30 (29.4%) had antibodies against a combination of those antigens. Compared with seronegative dogs, seropositive dogs were more likely to be herding dogs and to be female, whereas toy dogs were less likely to be seropositive. Seropositive dogs were also more likely to be lame or have arthritis-related lameness, nasal discharge or epistaxis, or splenomegaly. CONCLUSIONS AND CLINICAL RELEVANCE: Only a small percentage of dogs from which serum samples were obtained had antibodies against Bartonella spp. Breed appeared to be an important risk factor for seropositivity. Bartonella infection should be considered in dogs with clinical signs of lameness, arthritis-related lameness, nasal discharge or epistaxis, or splenomegaly.     

VERTEBRAL HEART SIZE RANGES SPECIFIC FOR WHIPPETS

To assess the influence of breed, breeding lines, and training on heart size, the vertebral heart size (VHS) was evaluated on left-to-right lateral, right-to-left lateral, dorsoventral, and ventrodorsal thoracic radiographs from 44 whippets free from cardiac and pulmonary disease. In lateral views, the VHS was 11.0 +/- 0.5 vertebrae (mean +/- SD) on right-to-left lateral and 11.3 +/- 0.5 vertebrae on left-to-right lateral radiographs, being larger than the 9.7 +/- 0.5 vertebrae proposed by Buchanan (P<0.0001). The VHS on left-to-right lateral views was larger than on right-to-left lateral views (P<0.0001). The VHS was 10.5 +/- 0.6 vertebrae on dorsoventral radiographs and 11.1 +/- 0.6 vertebrae on ventrodorsal radiographs. Both values were larger than the 10.2 +/- 1.5 vertebrae (dorsoventral) (P<0.0082) or 10.2 +/- 0.8 vertebrae (ventrodorsal) (P<0.0001) proposed by Buchanan. In addition, the VHS on ventrodorsal views was larger than on dorsoventral views (P<0.0001). Dogs out of racing pedigree lines had a significantly larger VHS than those out of show pedigree lines, and trained dogs had a significantly larger VHS than nontrained dogs. Because most trained dogs came out of racing pedigree lines, and all nontrained dogs came out of show pedigree lines, however, it is difficult to determine whether the higher VHS for trained dogs is due to genetic influences or training, or both. In conclusion, it is important to take into account the breed and the radiographic view when evaluating heart size in thoracic radiographs of whippets to avoid overinterpretation of cardiac enlargement in these dogs.     

A zoospore inhibition technique to evaluate the activity of antifungal compounds against Batrachochytrium dendrobatidis and unsuccessful treatment of experimentally infected green tree frogs (Litoria caerulea) by fluconazole and benzalkonium chloride

Effective and safe treatments of chytridiomycosis in amphibians, caused by Batrachochytrium dendrobatidis, are needed to help prevent mortality in captive programs for threatened species, to reduce the risk of spread, and to better manage the disease in threatened populations. We describe a simple method to determine minimum inhibitory concentrations (MICs) of antifungal agents that involves adding zoospores to various drug concentrations in 96 well plates and microscopic observation after four days. We report results from testing 10 commercially available antifungal compounds: benzalkonium chloride (<0.78 μg/ml), povidone iodine (312.5 μg/ml), amphotericin B (3.125 μg/ml), fluconazole (<1.56 μg/ml), itraconazole (<1.56 μg/ml), enilconazole (<1.56 μg/ml), mercurochrome (6.25 μg/ml), sodium chloride (12.5 mg/ml), methylene blue (<1.56 μg/ml) and Virkon (3.125 μg/ml). For treatment trials of juvenile Litoria caerulea, baths of benzalkonium chloride at 1 mg/L and fluconazole at 25 mg/L were used on 18 experimentally infected frogs per treatment. Although these treatments resulted in longer survival times (mean 43.7 ± 11.3 days) than in the untreated controls (37.9 ± 9.3 days), the mortality rate was still 100%. Higher doses of fluconazole are suggested for further animal trials.