Penetration of tinidazole into the gingival crevicular fluid in dogs

Tinidazole was administered as a single oral dose of 15 mg kg-1 to 12 dogs, and its concentration in the plasma and gingival crevicular fluid (GCF) was measured at one and two hours by high performance liquid chromatography. Tinidazole was detectable in GCF in five dogs at one hour (6.8 +/- 2.6 micrograms ml-1) and in six dogs at two hours (9.2 +/- 1.4 micrograms ml-1) and in all plasma samples. In those animals with no detectable tinidazole in GCF, either the concentration of tinidazole in plasma was low or the volume of the GCF sample was insufficient for determination. The observed tinidazole levels in GCF exceeded the minimal inhibitory concentration values for most anaerobic oral bacteria.     

Ultrastructural study of sheep lacrimal glands.

Sheep lacrimal glands are mixed glands, consisting of tubulo-acinar units succeeded by ducts of simple morphology. The secretory portions consist of three cell types: mucous, seromucous and serous, which may be intermingled in the same acinus or may form acini wholly made of only serous or mucous cells. Mucous cells show a rough endoplasmic reticulum that is reduced to a few cisternae located near the cell base and among the interstices of the secretory droplets. Mucous granules appear uniformly electron-lucent. Serous cells display a typical structure; serous granules can be uniformly electron-dense or composed of dense inclusions dispersed in an electron-lucent matrix. The seromucous granules have a bizonal substructure: a dense core is embedded in a highter matrix. Secretory acini are succeeded by intercalated ducts; the epithelium of these ducts gradually increases in height to form a kind of excretory duct, without the intervention of striated ducts.     

Complex carbohydrate histochemistry and ultracytochemistry of the sheep lacrimal gland

The chemical content of the secretion of the sheep lacrimal gland was analysed at the light and electron microscope levels by applying histochemical techniques and an ultrastructural histochemical method (periodic acid, thiocarbohydrazide and silver proteinate). Mucosubstance histochemistry demonstrated acidic glycoconjugates, mainly sulphated, in the mucous and seromucous glandular cells and in the apical portion of the cells lining the terminal ducts. Moreover, secretory granules, stained with PA-TCH-SP, showed a different localization of the reaction product. The presence of lysozyme was also found in the glandular serous cells. These histochemical studies demonstrate that the secretion of sheep lacrimal glands is mixed, having serous, mucous and seromucous components, and that an excellent correlation exists between the secretory granule substructure and glycoprotein localization.     

Efficacy of ivermectin jetting fluid against strike by some primary and secondary blowflies of sheep

SUMMARY Merino sheep, which were hand jetted with ivermectin jetting fluid, and untreated sheep were challenged with larval implants of Lucilia cuprina, Lucilia sericata, Calliphora noclva and Chrysomya ruflfacles at intervals of about 2 weeks from 6 to 16 weeks after treatment. Both Lucilia species produced strike rates of about 90% in untreated sheep; the respective rates were lower for Chr rufifacies (55%) and C nociva (60%). Strike rates for the treated group were about 17, 11, and 9% for L cuprina, L sericata, and Chr rufifacies, respectively. Only 1 implant site in the treated group was struck by C nociva. Treated sheep had significantly (P < 0.01) longer time to first strike than did untreated ones for each species of fly. L sericata, Chr rufifacies, and C nociva larvae implanted on treated animals had significantly (P < 0.05) longer time to first strike than did L cuprina larvae.     

Penetration of a topically applied nonsteroidal anti-inflammatory drug into local tissues and synovial fluid of dogs

OBJECTIVE: To investigate penetration of a topically applied nonsteroidal anti-inflammatory drug (NSAID) into tissues and synovial fluid. ANIMALS: 5 Greyhounds. PROCEDURE: Dogs were anesthetized and microdialysis probes placed in the dermis and gluteal muscle over each coxofemoral (hip) joint. Methylsalicylate (MeSA) was applied topically over the left hip joint. Dialysate and plasma (blood samples from the cephalic and femoral veins) were obtained during the subsequent 5 hours. Dogs were euthanatized, and tissue samples and synovial fluid were collected and analyzed for salicylic acid (SA) and MeSA by use of high-pressure liquid chromatography. RESULTS: SA and MeSA concentrations increased rapidly (< 30 minutes after application) in dialysate obtained from treated dermis. Salicylic acid also appeared in plasma within 30 minutes and reached a plateau concentration after 2 hours, although combined drug concentrations (SA plus MeSA) in plasma obtained from femoral vein samples were twice those measured in plasma obtained from the cephalic vein (SA only). Treated muscle had a progressive decrease in NSAID concentration with increasing depth (SA and MeSA), but it was significantly higher than the concentration in untreated muscle. Substantial amounts of SA and MeSA were also measured in synovial fluid of treated joints. CONCLUSIONS AND CLINICAL RELEVANCE: Topically applied NSAIDs can penetrate deeply into tissues and synovial fluid. Local concentrations higher than circulating systemic concentrations are suggestive that direct diffusion and local blood redistribution are contributing to this effect. Systemic blood concentrations may be inadequate to describe regional kinetics of topically applied drugs.     

Toxoplasmosis in a flock of sheep: some investigations into its source and control

Toxoplasmosis was thought to be a minor problem on a lowland sheep farm purchasing some 200 ewe lambs annually. Serological investigations and production records suggested a more substantial problem with most of the ewe lambs seroconverting during their first pregnancy, many while still at grass and receiving no supplementary food. Only 60 live lambs were produced per 100 ewe lambs tupped. It was known that cats occasionally inhabited the sheep houses, from which straw bedding was spread onto the pastures after lambing. Trials over two years with ewe lambs grazing either 'clean' or 'dirty' pastures indicated that the straw bedding was the most likely source of infection. Serial serological studies not only defined the time of infection but also showed that the ewe lambs could be kept free of infection and produce more live lambs; 58 live births came from 81 'clean' ewe lambs compared with 21 from 50 'dirty' ewe lambs.     

The pharmacokinetics of some aminoglycoside antibiotics in the horse

The disposition kinetics and bioavailability of streptomycin, kanamycin and neomycin were determined following their administration as parenteral preparations to horses. Single doses (10 mg/kg) of each aminoglycoside were given by the intravenous (i.v.) and intramuscular (i.m.) routes and, at a later time, seven intramuscular doses were injected at 12-h intervals. The pharmacokinetic behaviour of the three aminoglycosides was similar, in that a rapid distribution phase was followed by a relatively short half-life. The half-life (mean ± SD, n= 6) of kanamycin (1.80 ± 0.17 h) was significantly (P<0.01; t test, 10 d.f.) shorter than that of streptomycin (3.40 ± 0.42 h), while neomycin half-life (2.10 ± 0.97 h) was of an intermediate length. The apparent volume of distribution of neither kanamycin nor neomycin varied significantly (P > 0.05) from that of streptomycin and numerically (V¹ d = 230 ml/kg) was the same as the extracellular fluid volume. The body clearance of kanamycin (88.5 ± 11.3 ml/kg.h) was significantly (P < 0.01) larger than that of streptomycin (47.5 ± 7.9 ml/kg.h), while a significant difference in this parameter did not exist (P > 0.05) between neomycin and streptomycin. Following intramuscular injection, each aminoglycoside was rapidly and completely absorbed from the injection site, although neomycin showed wide individual variation in the fraction absorbed. The administration of multiple doses did not change either the bioavailability or the apparent half-life from the values obtained after a single dose. The only pharmacokinetic difference between these aminoglycosides that is of clinical importance lies in the rate of their elimination. A dosage interval of 8 h would be appropriate for kanamycin compared with a 12-h interval for streptomycin. The dosage interval for neomycin based on half-life should be 8 h but, due to the relatively greater toxicity of this aminoglycoside, an interval of 12 h might be recommended. The height of the peak serum concentration is determined by the size of the dose.     

Penetration of oxytetracycline into tissue-cages in calves

Concentrations of oxytetracycline (OTC) in serum and tissue-cage fluid (TCF) from subcutaneous tissue-cages were determined after single and repeated intravenous and intramuscular doses of 10 mg/kg to calves. Intravenous administration resulted in higher levels, and greater area under curve (AUC) in TCF, than did intramuscular administration. However, the penetration measured as the ratio of AUC in TCF to AUC in serum was equal, and therefore independent of the route of administration. A linear relationship between AUC in serum and AUC in TCF could be demonstrated. Half-lives of OTC in serum were 4.9 +/- 3.1 h after intravenous, and 6.1 +/- 2.0 h after intramuscular administration. In TCF the half-lives were 21.5 +/- 4.4 h and 24.5 +/- 11.5 h after intravenous and intramuscular administration, respectively. Repeated dosing resulted in accumulation of OTC in TCF. Lesser accumulation in older cages indicated altered characteristics of the cages with the passage of time. In serum, no substantial accumulation was seen after repeated i.v. dosing until the dosing interval was shortened to 6 h.     

Role of the harderian gland in immunoglobulin A production in chicken lacrimal fluid

The role of the Harderian gland (HG) in the production of immunoglobulin, especially IgA, was investigated. Lacrimal immunoglobulin almost disappeared after surgical removal of the HG and immunoglobulin produced by HG cells was detected in saliva but not in the trachea. Immunoglobulin production occurred in HG cell culture in vitro and it consisted mostly of IgA; the production of IgM and IgG was very low. These findings indicate that lacrimal IgA is produced locally in the HG and lacrimal IgG and IgM are mostly transported from the blood.     

Anatomic and radiographic studies of the lacrimal drainage system in sheep (Ovis aries)

The lacrimal drainage system of the sheep (Ovis aries) was studied, using radiographic and anatomic techniques. The straight course of the nasolacrimal duct and the adequate diameter of different parts of the system facilitates radiography and catheterization of the lacrimal drainage system.     

Secretion of endogenous urea into the cecum in sheep

In one-hour intervals before feeding and 1, 2, 3, 4 and 5 hours after feeding, three wethers were studied for the quantitative secretion of urea N and ammonia N into the caecum pouch (volume 80 ml). The amount of ammonia N secreted into the caecum ranged from 10.0 +/- 2.8 to 20.0 +/- 3.5 microM/h. The concentration of ammonia N was 271.2 +/- 60.6 microM/l, on the average. The passage of urea N showed no statistically significant differences before and after feeding (37.8 +/- 4.2 - 41.4 +/- 5.0 microM/h). The concentration of urea N in the caecum pouch was from 617.8 +/- 67.8 microM/l to 710.7 +/- 82.1 microM/l. Urea penetrates through the caecum wall into the caecum mostly in the form of a whole molecule, only its small proportion has the form of ammonia, its hydrolysis product.