Lead poisoning in a dog--a case report.

Lead poisoning in a bitch is described. Clinical signs, hematological and biochemical changes, X-ray, as well as presence of lead in stomach and blood confirmed the diagnosis.     

Primary gastric histiocytic sarcoma in a dog--a case report

A 12-year-old intact female mixed breed dog was presented for chronic, intermittent vomiting and diarrhoea. On endoscopic examination a protruding mass arising from the mucosal surface of the pyloric region was detected. Cytological and histological examination revealed an accumulation of pleomorphic round/oval phagocytic cells suggesting histiocytic origin. This was confirmed by immunohistochemistry. No extra-gastric involvement was detected on clinical examination or at necropsy. This is the first report of primary gastric histiocytic sarcoma in a dog.     

Scleral and suprachoroidal foreign body in a dog--a case report

A 2-year-old male castrated Springer Spaniel with a 3-week history of waxing and waning right sided exophthalmos, periorbital swelling, chemosis, and fundic changes was examined. Ophthalmic examination of the right eye revealed slight chemosis and nictitating membrane protrusion. Indirect ophthalmoscopy showed an approximately 8 mm peripapillary hyporeflective tapetal lesion with subretinal edema consistent with a bulbar/retrobulbar disease process. Inflammatory or neoplastic diseases were the main differential diagnoses. Ancillary diagnostics (ocular ultrasound and computed tomography) showed a focal, poorly defined dense tissue involving the caudomedial aspect of the right globe, adjacent to the optic nerve head without apparent orbital involvement. Considering the duration, location, and severity of the clinical findings, enucleation of the right globe was performed. Histopathology revealed focal thickening of the posterior wall with severe pyogranulomatous inflammation, surrounding a foreign body most consistent with plant material embedded between the sclera and the choroid (suprachoroidal). This report describes a rare case of a scleral/suprachoroidal foreign body (plant material), and outlines the difficulty of establishing an etiological diagnosis using standard ocular imaging.     

Pharmacokinetics of single-dose intravenous or intramuscular administration of gentamicin in roosters

Healthy mature roosters (n = 10) were given gentamicin (5 mg/kg of body weight, IV) and, 30 days later, another dose IM. Serum concentrations of gentamicin were determined over 60 hours after each drug dosing, using a radioimmunoassay. Using nonlinear least-square regression methods, the combined data of IV and IM treatments were best fitted by a 2-compartment open model. The mean distribution phase half-life was 0.203 +/- 0.075 hours (mean +/- SD) and the terminal half-life was 3.38 +/- 0.62 hours. The volume of the central compartment was 0.0993 +/- 0.0097 L/kg, volume of distribution at steady state was 0.209 +/- 0.013 L/kg, and the total body clearance was 46.5 +/- 7.9 ml/h/kg. Intramuscular absorption was rapid, with a half-life for absorption of 0.281 +/- 0.081 hours. The extent of IM absorption was 95 +/- 18%. Maximal serum concentration of 20.68 +/- 2.10 micrograms/ml was detected at 0.62 +/- 0.18 hours after the dose. Kinetic calculations predicted that IM injection of gentamicin at a dosage of 4 mg/kg, q 12 h, and 1.5 mg/kg, q 8 h, would provide average steady-state serum concentrations of 6.82 and 3.83 micrograms/ml, with minimal steady-state serum concentrations of 1.54 and 1.50 micrograms/ml and maximal steady-state serum concentrations of 18.34 and 7.70 micrograms/ml, respectively.     

Combined pharmacokinetics of gentamicin in pony mares after a single intravenous and intramuscular administration

Healthy mature pony mares (n = 6) were given a single dose of gentamicin (5 mg/kg of body weight) IV or IM 8 days apart. Venous blood samples were collected at 0, 5, 10, 20, 30, and 45 minutes and at 1, 1.5, 2, 2.5, 3, 4, 6, 8, 10, 12, 18, 24, 30, 36, 40, and 48 hours after IV injection of gentamicin, and at 10, 20, 30, and 45 minutes and at 1, 1.5, 2, 2.5, 3, 4, 6, 8, 10, 12, 18, 24, and 30 hours after IM injection of gentamicin. Gentamicin serum concentration was determined by a liquid-phase radioimmunoassay. The combined data of IV and IM treatments were analyzed by a nonlinear least-square regression analysis program. The kinetic data were best fitted by a 2-compartment open model, as indicated by residual trends and improvements in the correlation of determination. The distribution phase half-life was 0.12 +/- 0.02 hour and postdistribution phase half-life was 1.82 +/- 0.22 hour. The volume of the central compartment was 115.8 +/- 6.0 ml/kg, volume of distribution at steady state was 188 +/- 9.9 ml/kg, and the total body clearance was 1.27 +/- 0.18 ml/min/kg. Intramuscular absorption was rapid with a half-life for absorption of 0.64 +/- 0.14 hour. The extent of absorption was 0.87 +/- 0.14. Kinetic calculations predicted that IM injections of 5 mg of gentamicin/kg every 8 hours would provide average steady-state serum concentrations of 7.0 micrograms/ml, with maximum and minimum steady-state concentrations of 16.8 and 1.1 micrograms/ml, respectively.     

Pathologic changes and tissue gentamicin concentrations after intravenous gentamicin administration in clinically normal and endotoxemic cats

Hematologic and serum biochemical values, tissue gentamicin concentrations, and renal pathologic changes were determined in clinically normal and endotoxemic cats given 3 mg of gentamicin/kg of body weight, IV. Endotoxemia was induced by IV administration of 0.5 microgram of Escherichia coli endotoxin/kg of body weight. In experiment 1, 6 cats were given endotoxin. After rectal temperature increased at least 1 degree C, cats were given gentamicin. Blood samples were collected before and at 1 and 3 hours after administration of gentamicin. With the exception of severe leukopenia, other hematologic changes or changes in serum biochemical values were not observed. In experiment 2, 24 cats were allotted to 4 groups and were given gentamicin, endotoxin, gentamicin plus endotoxin, or neither substance. Three hours later, cats were euthanatized, and tissue and body fluid specimens were obtained and were assayed for gentamicin concentration. Kidney specimens were examined microscopically. Endotoxemic cats had more gentamicin in the renal medulla than did control cats, but none of the cats had detectable renal lesions. The possible nephrotoxic synergism between gentamicin and severe endotoxemia and the lack of major differences in gentamicin concentration in extrarenal tissues indicated that the dosage of gentamicin in endotoxemic cats does not have to exceed the dosage recommended for clinically normal cats. A single dose of gentamicin administered IV did not cause renal damage in mildly endotoxemic cats, but nephrotoxicity ascribed to multiple doses of gentamicin in more severely endotoxemic cats needs to be evaluated.     

Concentrations of gentamicin in serum and bronchial lavage fluid after intravenous and aerosol administration of gentamicin to horses

OBJECTIVE: To compare concentrations of gentamicin in serum and bronchial lavage fluid after IV and aerosol administration of gentamicin to horses. ANIMALS: 9 healthy adult horses. PROCEDURE: Gentamicin was administered by aerosolization (20 ml of gentamicin solution [50 mg/ml]) and IV injection (6.6 mg of gentamicin/kg of body weight) to each horse, with a minimum of 2 weeks between treatments. Samples of pulmonary epithelial lining fluid were collected by small volume (30 ml) bronchial lavage 0.5, 4, 8, and 24 hours after gentamicin administration. Serum samples were obtained at the same times. All samples were analyzed for gentamicin concentration, and cytologic examinations were performed on aliquots of bronchial lavage fluid collected at 0.5, 8, and 24 hours. RESULTS: Gentamicin concentrations in bronchial lavage fluid were significantly greater 0.5, 4, and 8 hours after aerosol administration, whereas serum concentrations were significantly less at all times after aerosol administration, compared with IV administration. Neutrophil counts in bronchial lavage fluid increased from 0.5 to 24 hours, regardless of route of gentamicin administration. CONCLUSIONS AND CLINICAL RELEVANCE: Aerosol administration of gentamicin to healthy horses resulted in gentamicin concentrations in bronchial fluid that were significantly greater than those obtained after IV administration. A mild inflammatory cell response was associated with aerosol delivery of gentamicin and repeated bronchial lavage. Aerosol administration of gentamicin may have clinical use in the treatment of bacterial bronchopneumonia in horses.     

Pharmacokinetics of gentamicin following single dose intravenous administration in normal and febrile goats

A pharmacokinetic study of gentamicin (5 mg/kg intravenous (i.v.)) was conducted first in cinically healthy female goats and then in the same goats after induction of fever by Escherichia coli endotoxin (0.2 μg/kg i.v.). Rectal temperature increased 1 to 1.5°C in febrile goats. Differences in the blood serum concentrations of gentamicin were not observed at any time between febrile and normal goats. The disposition kinetics of gentamicin were described by a biex-ponential expression C_P= Ae^-αt+ Be^-β. Median values for the half-lives of gentamicin were 103.6 min in normal and 136.0 min in febrile goats. The apparent volume of distribution (V_d) was 263.3 ml/kg in the febrile goats which was not different from that in the normal goats (240.6 ml/kg). The volume of the central compartment (V_c) was almost identical in normal and febrile goats. The body clearance (Cl_β) was observed to be 1.7 and 1.6 ml/min-kg in normal and febrile goats, respectively. Dosage regimens for gentamicin were calculated on the basis of median kinetic data.     

Evaluation of systemic administration of gentamicin for treatment of coliform mastitis in cows

Recovery of cows (n = 61) with mastitis caused by gram-negative bacteria and treated systemically with an antibiotic (gentamicin) to which the bacteria were susceptible in vitro, was compared with recovery of cows (n = 13) with similar infections treated with a systemically administered antibiotic (erythromycin) to which the bacteria were resistant in vitro or with recovery of cows (n = 12) not given an antibiotic systemically. In the first part of the study, cows were selected for treatment groups by use of a diagnostic scheme designed to predict whether the mastitis was caused by gram-negative or gram-positive bacteria. In the second part of the study, all cows were treated without systemic administration of an antibiotic. Significant difference was not observed in the outcome of the disease between cows given gentamicin and cows of the other 2 treatment groups at 24 hours or at 4 weeks after treatment. At 24 hours after initial treatment, 71.9% of cows treated with gentamicin, 92.3% of those treated with erythromycin, and 45.5% not treated systemically had improved appetite. At 4 weeks after initial treatment, of the cows treated with gentamicin, 11.5% died; in 32.8%, lactation ceased in the affected mammary gland; in 21.3%, lactation was decreased in the affected gland; and 34.4% returned to normal lactation and health. Of cows treated with erythromycin, none died; in 23%, lactation ceased in the affected mammary gland; in 23%, lactation decreased in the affected gland; and 54% returned to normal lactation and health.(ABSTRACT TRUNCATED AT 250 WORDS)     

Regional intravenous limb perfusion compared to systemic intravenous administration for marimastat delivery to equine lamellar tissue

Pharmaceutical agents with potential for laminitis prevention have been identified. Many of these, including the MMP inhibitor marimastat, are impractical for systemic administration. This study compared local delivery of marimastat by regional limb perfusion (RLP) to systemic intravenous bolus dosing (SIVB), and established whether RLP results in local lamellar drug delivery. Six adult horses received 0.23 mg/kg of marimastat by RLP followed by 0.23 mg/kg marimastat by SIVB, with a 24‐h washout period. Lamellar ultrafiltration probes sampled lamellar interstitial fluid as lamellar ultrafiltrate (LUF). LUF and plasma marimastat concentrations (LUF_[M] and P_[M], respectively) were measured for 24 h after each treatment. Regional pharmacokinetic parameters were calculated using noncompartmental analyses. The LUF C_max following RLP was 232 [34–457] times that following SIVB. LUF_[M] after RLP were higher than those obtained after SIVB for 18 h (P < 0.03). Median LUF_[M] were > IC₉₀ of equine lamellar MMP‐2 and MMP‐9 for 9 h after tourniquet removal. RLP appeared superior to SIVB for lamellar marimastat delivery (higher LUF C_max,, AUC and T > IC₉₀ of lamellar MMPs). However, frequent dosing is necessary to achieve therapeutic lamellar concentrations. RLP could be used to investigate whether marimastat prevents experimentally induced laminitis. Further refinement of the technique and dosing interval is necessary before clinical application.     

Intramammary administration of gentamicin as treatment for experimentally induced Escherichia coli mastitis in cows.

In 8 Holstein cows, 50 colony-forming units (CFU) of Escherichia coli was administered into 1 mammary gland. Infections were established in all inoculated glands. In 4 of the 8 cows, 500 mg of gentamicin sulfate was administered by intramammary infusion 14 hours after inoculation; the other 4 cows were untreated controls. Infusions of gentamicin also were given after each of the 3 successive milkings after the initial infusion, so that a total dose of 2 g of gentamicin was given to each of the treated cows. During the 33-hour treatment period and for the first milking after the last infusion of gentamicin, the treated cows had a mean gentamicin concentration of greater than or equal to 31.0 micrograms/ml in milk samples that were collected from inoculated quarters immediately before each milking. Concentrations of 0.34 and 0.69 micrograms of gentamicin/ml were detected in milk from 2 cows at 8 days after inoculation with E coli. Mean serum concentrations of gentamicin were greater than or equal to 0.37 micrograms/ml throughout the treatment period and the first 12 hours after the last infusion, with a mean peak concentration of 0.96 micrograms/ml at 24.4 hours. The range of peak concentration of gentamicin detected in urine from all treated cows was 42 to 74.4 micrograms/ml. Peak concentration of E coli in milk in the treated cows (6.08 +/- 1.02 log10 CFU/ml) did not significantly (P greater than 0.05) differ from that of the control cows (5.26 +/- 1.00 log10 CFU/ml). Similarly, mean duration of infection in the treated cows (54 hours) did not differ significantly from that of the control cows (48 hours).(ABSTRACT TRUNCATED AT 250 WORDS)     

Clinical efficacy of intravenous administration of marbofloxacin in a Staphylococcus aureus infection in tissue cages in ponies

Tissue cages (TC), implanted subcutaneously in the neck in eight ponies, were inoculated with Staphylococcus aureus (S. aureus) to determine the clinical efficacy of marbofloxacin in the treatment of this infection. From 21 h after inoculation, marbofloxacin (6 mg/kg) was administered intravenously (i.v.) once daily for 7 days. Samples of the tissue cage fluid (TCF) were taken to determine marbofloxacin concentrations (days 1, 3 and 7), using high-pressure liquid chromatography, and numbers of viable bacteria [colony forming units (CFU)] (days 1, 3, 7, 14 and 21). Statistical analysis was used to compare CFU before and after treatment. Clinical signs and CFU were used to evaluate the efficacy of treatment. Although, there was a slight decrease in CFU in all TC initially, the infection was not eliminated by marbofloxacin treatment in any of the ponies and abscesses formed. As the MIC (0.25 microg/mL) did not change during treatment and the concentration of marbofloxacin during treatment (mean concentration in TCF was 0.89 microg/mL on day 1, 0.80 microg/mL on day 3 and 2.77 microg/mL on day 7) was above MIC, we consider that the treatment failure might be attributable to the formation of a biofilm by S. aureus. Based on the present results, i.v. administration of marbofloxacin alone is not suitable for the elimination of S. aureus infections from secluded sites.