Pharmacokinetics of oxytetracycline hydrochloride in rabbits

Pharmacokinetics of oxytetracycline HCl (OTC) was studied in rabbits. After 10 mg of OTC/kg of body weight was administered IV, the distribution half-life was 0.06 hour, terminal half-life was 1.32 hours, volume of distribution area was 0.861 L/kg, and total body clearance was 0.434 L/kg/h. After 10 mg of OTC/kg was given IM, the absorption half-life was 2.09 hours, extent of absorption was 71.4%, and total body clearance of the absorbed fraction was 0.576 L/kg/h. Based on these kinetic data, a dosage of 15 mg of OTC/kg, every 8 hours was developed. This dose given IM for 7 consecutive days resulted in observed steady-state maximum and minimum concentrations (mean +/- SD) of 4.7 +/- 0.3 micrograms/ml and 3.2 +/- 0.6 micrograms/ml, respectively. Twice this dose (30 mg of OTC/kg, every 8 hours) given IM caused anorexia and diarrhea.     

The effects of selenium, housing and management on the incidence of pneumonia in housed calves

The occurrence and incidence of pneumonia in housed calves were not related to the selenium status of the herd as measured by blood glutathione peroxidase activity nor were they affected by selenium treatment of calves during the neonatal period. Pneumonia was related more closely to herd size and building design.     

The pathology of lens-induced uveitis in dogs

Rupture of the lens capsule in 20 dogs resulted in zonal, perilenticular inflammation that did not respond to symptomatic therapy and resulted in the loss of the globe. The reaction was dominated by lens epithelial proliferation, pupillary occlusion, and glaucoma in 11 of the 20. This reaction, herein named phacoclastic uveitis, is unique and easily distinguished from the mild lymphocytic-plasmacytic anterior uveitis that accompanies leakage of lens material through an intact capsule of a hypermature cataract (phacolytic uveitis). None of the dog eyes had the granulomatous perilenticular inflammation that is the hallmark of lens-induced (phacoanaphylactic) uveitis in humans.     

Free Flying Sparrows as Carriers of Salmonellosis

Salmonella typhimurium was isolated from nine of 60 wild sparrows trapped in the Guelph area. While this organism was isolated from birds trapped at several different locations, the highest prevalence was in sparrows trapped in close proximity to an animal clinic. The significance of these findings in relation to human and animal salmonellosis is discussed.     

Histopathology of Experimental Schistosoma bovis Infection in Goats

The inflammatory host response to Schistosoma bovis in young goats was studied at necropsy by light microscopy 34 weeks after primary exposure to 3,000 cercariae (group B, n=6), 34 weeks after primary exposure to 3,000 cercariae followed by challenge with 2,500 cercariae at week 17 (group C, n=5), and 17 weeks after primary exposure to 2,500 cercariae, given on week 17 of the experiment (group D, n=6). Three goats served as uninfected controls. The faecal egg output had been minimal for 17 weeks prior to necropsy in groups B and C and only for the last 2 weeks in group D.Histological studies were carried out on the small intestine, liver, lung and spleen, and tissue egg counts were performed. In sections of the small intestine and liver, a panel of histopathological variables were quantitated to characterize the host response and differences between groups of animals were evaluated with one way analysis of variance. The mean tissue egg count in the small intestine was slightly but not significantly higher in group C than group B and about twice as high in group D (D vs B or C p<0.01). Group means of numbers of inflammatory foci per section of gut wall corresponded well with those of tissue egg counts, suggesting that the rate of inflammatory destruction of eggs did not differ markedly between the groups. Egg material was less commonly seen in granulomas of the small intestine in group B than in group D (p<0.01), suggesting lower passage of eggs through the gut wall during the later than during the earlier phase of patent primary infection. The frequency of eosinophil-rich hepatic inflammatory foci was much higher in group D than in the other groups (D vs B p<0.05, D vs C p< 0.01), and coincided with a high degree of blood eosinophilia in this group at the time of sacrifice. Challenged goats showed a significantly higher frequency of markedly fibrotic inflammatory foci in the liver and of liver granulomas with a marked giant cell component than goats of the other groups. Hepatic portal fibrosis was least prominent in animals with 17- week- old primary infections, implying a possible relation between this change and duration of infection.