Pulmonary bacterial deposition and clearance during ascarid larval migration in weanling pigs.

Pulmonary deposition and clearance of bacteria were measured in weanling pigs, half of which had been inoculated at age 31 days with larvated Ascaris suum ova. Seven days later, when breathing signs of larval migration were pronounced, all pigs were exposed to aerosolized Escherichia coli (strain B). Then, either immediately after aerosol exposure (for deposition assessment) or immediately after a 120 minute period in filtered air (for clearance), bacteria in the pigs' lungs were counted. Ascarid ova-inoculated pigs did not differ significantly from control pigs for number of bacteria in the lungs after aerosol exposure, but after the 120 minute clearance period they had 7.2 times more than did the control pigs. Thus, in weanling pigs, the breathing-pattern changes that were evident during ascarid-larval migration did not affect pulmonary deposition of inhaled bacteria significantly, but the presence of ascarid larvae in the lungs was associated with impaired pulmonary bacterial clearance.     

Assessment of toxicosis induced by high-dose administration of milbemycin oxime in collies

Fifteen Collies, previously having mild reactions to ivermectin challenge (120 micrograms/kg of body weight; 20 times the recommended dosage level), were studied to evaluate the effects of milbemycin oxime administration at 5 and 10 mg/kg (10 and 20 times the manufacturer's recommended dosage). Five replicates, comprising 3 dogs each, were formed on the basis of body weight. Within replicates, each dog was randomly allocated to treatment with 5 or 10 mg of milbemycin/kg or served as a untreated control. Dogs were examined repeatedly for signs of toxicosis for 4 days after treatment and daily thereafter. Two of 5 dogs treated at 5 mg/kg (10x) developed signs of mild depression on the day of treatment, but were normal 24 hours after treatment. All 5 dogs treated at 10 mg/kg (20x) developed signs of mild depression and ataxia by 6 hours. Signs persisted for 24 hours in 3 dogs. Two of these dogs also had mydriasis, whereas 3 salivated excessively. All dogs recovered completely by day 2 after treatment. The results of this study demonstrated that Collies sensitive to the effects of 120 micrograms of ivermectin (20x)/kg show similar sensitivity to the effects of milbemycin oxine administered at 10 mg/kg (20x). We conclude that ivermectin and milbemycin commercial formulations have similar margins of safety and that milbemycin toxicosis appears to be dose-dependent in Collies with a demonstrated sensitivity to ivermectin.     

A selective procedure for the field isolation of pathogenic Streptococcus spp. of rainbow trout (Salmo gairdneri)

A procedure established for the selective isolation of the species of Streptococcus responsible for rainbow trout streptococcosis in South Africa, consisted of the inoculation of samples into nutrient broth which had been supplemented with 100 micrograms/ml of nalidixic acid, 160 micrograms/ml of oxolinic acid or 200 micrograms/ml of sodium azide. After incubation, the sample was plated onto tetrazolium agar on which the rainbow trout pathogenic Streptococcus species grew as a red colony. The colonies were isolated from the tetrazolium agar and identified as rainbow trout pathogenic isolates by biochemical and serological tests. In the laboratory the selective procedure is capable of detecting about 2 bacteria per ml. This procedure was used in the field and biochemically identical Streptococcus species were found in the mud and a freshwater crab from the water source of a site with a history of streptococcosis.     

Epidemiology of Salmonella typhimurium infection in calves: excretion of S typhimurium in the faeces of calves in different management systems

Twenty-five batches of market-purchased calves, comprising 589 animals on 11 farms, were examined for the excretion of salmonellas for at least 28 days after their arrival. Salmonellas were found in 217 (51 per cent) of 423 calves from 18 of 21 batches on nine farms. The calves were housed in single pens on eight farms and in groups on the others. The trends in new excreters and the proportion of Salmonella typhimurium excreters were similar in both types of housing, a peak of excretion which was slightly higher in single penned calves, being reached 18 to 19 days after arrival. New excreters were found at most samplings in both types of housing, but the peak of new excreters appeared earlier and declined sooner in single penned calves. On average, single penned animals excreted salmonellas longer. Salmonella dublin was found only in single-penned calves, and the trend in excretion was similar to that for S typhimurium in single-penned calves except that the peak was at about 28 days. Prophylactic feeding of antibiotics was practised on nine farms, but appeared to have no influence on the excretion of salmonellas. Salmonellas were isolated from the environment in six of nine farms studied, even after cleaning and disinfection. It is suggested that the persistence of salmonellas in the environment deserves more attention in the formulation of control programmes.     

Further controlled evaluations of fenbendazole as a bovine anthelmintic.

The efficacy of fenbendazole (methyl-5-(phenythio)-2-benzimidazole-carbamate) in cattle parasitized by the lungworm Dictyocaulus viviparus and in other cattle parasitized by Haemonchus, Ostertagia, Trichostrongylus, Cooperia, and Oesophagostomum was investigated in 3 controlled critical experiments. A single treatment with 5.0 mg/kg of body weight administered in the feed or in a 10% suspension exceeded 99% efficacy against these helminths. Dosages of 1, 0.5, 0.35, and 0.25 mg/kg of body weight administered for 5 days to individual calves in their feed were 99% efficacious against all helminths, except Haemonchus. The 1.0 mg/kg dose removed 99.5% of the Haemonchus, and the other 3 dosages had efficacies of 91.0, 93.7, and 95.6%, respectively. The small daily dosages were not evaluated against Dictyocaulus.     

Development of a polymerase chain reaction-based in vivo method in the diagnosis of subclinical pigeon circovirus infection

This paper describes a polymerase chain reaction (PCR)-based method performed on blood samples and intestinal content to detect subclinical pigeon circovirus (PiCV) infection in live pigeons. In addition, two sets of primers (primer set 1 and 2), designed in two different regions of the viral genome, were used to provide evidence of possible differences in PCR responses. Blood and intestinal content samples were randomly collected from a total of 50 apparently healthy meat pigeons, aged 1 to 5 wk, which came from central Italy. Samples of primary lymphoid organs were also collected. Results showed a high level of PiCV infection, although clinical signs were not present. The results obtained with the two sets of primers showed that primer set 2 was able to detect a higher number of PCR-positive pigeons (45 of 50 pigeons) than primer set 1 (11 of 50 pigeons). In both cases an increase in positive results with pigeon age indicates that the major direction of transmission is likely horizontal. In these circumstances feces can play an important epidemiologic role, as supported by the consistent circovirus detection in intestinal content. The high sensitivity of this PCR test, which is able to detect very low amounts of viral DNA (5.5 x 10(-3) fg of plasmid containing the cloned PiCV genome), makes it suitable for possible application as an epidemiologic tool for identifying virus carriers for subsequent removal from lofts.     

Efficacy and safety of a purified porcine insulin zinc suspension for managing diabetes mellitus in dogs

The objective of this study was to evaluate the safety and efficacy of a purified porcine insulin zinc suspension for treating dogs with uncomplicated diabetes mellitus. Fifty-three dogs were treated for 60 days after an initial dose determination period. The means of the blood glucose concentrations during 12-hour glucose curves and the means of the blood glucose nadir concentrations during 12-hour glucose curves for all dogs were determined before beginning insulin therapy (time 0), at the end of the dose determination period (time 1), 30 days after time 1 (time 2), and 60 days after time 1 (time 3). Presence of polyuria, polydipsia, and ketonuria was determined at each time point. Adequacy of control of hyperglycemia was based on 12-hour blood glucose curves and improvement in clinical variables (results of physical examinations, historic information, polyuria, polydipsia, and ketonuria). Safety was evaluated by questionnaire, performance of physical examination, CBC, serum chemistry profile, and urinalysis. The means of the blood glucose concentrations during 12-hour glucose curves and the means of the blood glucose nadir concentrations during 12-hour glucose curves for all dogs at times 1, 2, and 3 were significantly lower compared with time 0 (P < .0001). There was a reduction in the proportion of dogs with polyuria, polydipsia, and ketonuria of 82, 86, and 80%, respectively. All of the dogs had adequate glycemic control at time 1, 66% at time 2, and 75% at time 3. At time 3, 66% of dogs required insulin injections q12h. Other than hypoglycemia, there were no important adverse effects of insulin administration. The insulin, was safe and efficacious for reducing blood glucose and clinical signs in dogs with diabetes mellitus.     

Evaluation of enzyme-linked immunosorbent assays performed on milk and serum samples for detection of paratuberculosis in lactating dairy cows

OBJECTIVE: To determine whether results obtained for milk and serum samples with ELISAs intended for diagnosis of paratuberculosis in dairy cows were comparable to results obtained by means of mycobacterial culture of fecal samples. DESIGN: Cross-sectional study. ANIMALS: 689 lactating dairy cows in 9 Ontario herds. PROCEDURE: Milk, serum, and fecal samples were obtained from all cows. Fecal samples were submitted for mycobacterial culture. Serum samples were tested with a commercially available ELISA for antibodies against Mycobacterium paratuberculosis, and preserved milk samples were tested with an indirect ELISA for antibodies against M paratuberculosis. RESULTS: Results were positive for 130 of the 689 (18.9%) serum samples, 77 of the 689 (11.1%) milk samples, and 72 of the 689 (10.4%) fecal samples. The level of agreement between results for milk and serum samples was only moderate. Proportions of positive results for serum and fecal samples were significantly different, but proportions of positive results for milk and fecal samples were not significantly different. In addition, results for milk samples had a higher level of agreement with results of mycobacterial culture than did results for serum samples. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that the indirect ELISA used on milk samples may be a convenient method of detecting paratuberculosis in dairy herds.     

New data on the transmission of pigeon circovirus

Nineteen racing pigeons aged from one to five years were examined postmortem. pcr tests showed that the spleens of 16 of them were positive for pigeon circovirus, the livers of six were positive, and blood from one of them was positive for the virus. Five of 44 embryos in embryonated eggs collected from three lofts were positive by pcr, but swabs taken from the crops of 64 adult birds which were feeding one- to 10-day-old squabs in these three lofts were negative for the viral dna.