Host differences in response to trickle infection with Fasciola gigantica in buffalo, Ongole and Bali calves

Progressive weight gain, faecal egg counts, packed cell volume, percent eosinophils in blood, serum antibody and serum levels of glutamate dehydrogenase and gamma-glutamyl transpeptidase were recorded in seven swamp buffalo (Bubalis bubalis), 7 Ongole (Bos indicus) and four Bali calves (Bos sundiacus) which were infected orally with 15 metacercariae of Fasciola gigantica twice weekly for 32 weeks. Similar observations were made on four buffalo, 4 Ongole calves and 3 Bali calves maintained fluke-free as controls. Flukes were counted at slaughter 36 weeks after initial infection. Mean daily weight gains of infected Bali (228 ± 100 (SD) g/day) and infected Ongole calves (328 ± 57 (SD) g/day) were lower (p = 0.026 and 0.067, respectively) than those of control calves (405 ± 107 (SD) g/day), but infected buffalo calves (379 ± 78 (SD) g/day) had similar weight gains to those of the controls (p = 0.57). Throughout the trial, faecal Fasciola egg counts in buffaloes were about one-fifth of counts of Ongole calves, and counts in Bali calves were intermediate. Ongole calves had three times the number of flukes at slaughter in their liver compared to buffalo and Bali calves, which had similar numbers. However, there was evidence that Bali calves had acquired a degree of resistance about 24 weeks after infection commenced and may have lost adult flukes as a consequence.     

Netobimin in drinking water for treatment of bovine parasitic bronchitis: a field experiment

Lungworm-infected seeder calves were used on four 1.41 ha paddocks to ensure that groups of 11 calves would be exposed to a heavy challenge with Dictyocaulus viviparus. By the 39th day after turnout there was a serious episode of respiratory disease and a diagnosis of parasitic bronchitis was confirmed by post mortem and faecal examination. One group of trial calves was treated with netobimin administered in the drinking water at 2.8 mg/kg/day for seven consecutive days; another group received the same treatment supplemented with flunixin meglumine at 2.2 mg/kg/day for three days; a third group was given a single oral dose of 7.5 mg netobimin/kg; only emergency treatments were given to calves in the control group. The clinical response to the drinking water treatments was highly satisfactory and better than the response to the single oral treatment.     

Tissue concentrations and pharmacokinetics of florfenicol in male veal calves given repeated doses

The pharmacokinetic disposition of florfenicol was studied in male veal calves given 11 mg of florfenicol/kg of body weight, IV and 11 mg of florfenicol/kg PO every 12 hours for 7 doses. After florfenicol administration IV, the median elimination half-life was 222.8 minutes, whereas the median half-life of the distribution phase was 7.94 minutes. Median body clearance and apparent volume of distribution were 2.87 ml/kg/min and 0.907 L/kg, respectively. After florfenicol administration, PO, there was a wide variation in the calculated half-life, which was attributed to variation in the rate of florfenicol absorption. The half-life was 167.4 to 534.9 minutes after the first oral dose and 190 to 808.8 minutes after the seventh dose. The median bioavailability after the first oral dose was 0.8888. Peak and trough concentrations of florfenicol were increased after subsequent doses were administered, compared with those after the first oral dose. The percentage of protein binding in serum from one adult cow was 22% to 26%. Florfenicol concentrations in tissues and body fluids of male veal calves were studied after the seventh dose of 11 mg of florfenicol/kg. High concentrations of florfenicol were measured in the urine, kidney, and bile. Low concentrations were measured in the brain, CSF, and aqueous humor. Concentrations in all other tissues and fluids studied were similar to the concurrent serum concentration.     

Pharmacokinetics and urinary excretion of sulphadimidine in buffalo calves

Pharmacokinetics and urinary excretion of sulphadimidine (SDI) were determined in buffalo calves following single oral administration (150 mg/kg). The plasma levels of free sulphadimidine were above minimum effective therapeutic concentration (> 40 micrograms/ml) between 4 and 12 h and the N4-acetylated form of the drug was in the range of 7.2-19.3%. Kinetic evaluation of plasma levels was performed using a two-compartment open model. The absorption and elimination half-lives of SDI were 3.01 and 11.94 h, respectively. Based on this study, an optimal dosage regimen of sulphadimidine in buffalo calves would be 100 mg/kg, followed by 50 mg/kg at 12 h intervals. Sulphadimidine was mainly excreted in the urine as free amine. The percentage of N4-acetyl sulphadimidine in urine was comparatively higher than in plasma.     

Mast cell and eosinophils in the wall of the gut and eosinophils in the blood stream during Toxocara vitulorum infection of the water buffalo calves (Bubalus bubalis)

Toxocara vitulorum is a pathogenic nematode from the small intestine of very young buffalo calves. To understand the development of the inflammatory responses in the wall of the gut, samples of tissues were removed from the duodenum, jejunum and ileum of buffalo calves naturally infected with T. vitulorum during the beginning of the infection, at the peak of egg output, as well as during the periods of rejection of the worms and post-rejection. Two additional control groups of uninfected calves (by anti-helminthic therapy of their mothers and after the birth) were also necropsied on days 30 and 50 after birth. Blood samples were fortnightly collected from birth to 174 days post-birth. Blood smears were prepared and stained with Giemsa for eosinophils. The parasitological status of buffalo calves was evaluated through weekly fecal egg counts (EPG) from 1 to 106 days after birth, which revealed that T. vitulorum egg shedding started on day 11, reached the peak of the infection on day 49 and finally expelled the parasites between days 50 and 85 after birth. In the infected buffalo calves, the mast cell population increased significantly, by two-fold in the mucosa (villus-crypt unit (VCU)) of the duodenum and four-fold in the proximal jejunum; but these increases were statistically significant only at the peak of the infection. Although mast cell numbers increased in the mucosa of the ileum as well as in both the submucosal and muscle tissues of the duodenum, proximal jejunum and ileum, the data was not significantly different from the controls. Eosinophil numbers increased in the mucosa of the duodenum (two-five times higher than the control) and proximal jejunum (three-five-fold) during the period of the infection (beginning, peak and rejection). The relative numbers of eosinophils increased in the blood stream from the second to the seventh week. In conclusion, T. vitulorum infection elicited mastocytosis and tissue eosinophilia in the duodenum and proximal jejunum, as well as eosinophilia in the blood stream, during the beginning, at the peak and during the rejection of the worm. After the rejection of the worms, the numbers of these cells returned to normal levels suggesting that these cells may have a role in the process of rejection of T. vitulorum by the host.     

Biologic quality of colostrum and calves from dairy cows injected with zinc during pregnancy]

The effects of an administration of the Zindep inj. preparation (Biotika) were evaluated in pregnant dairy cows as exerted on specific weight, total protein (TP) content, total immunoglobulin (IgC) and albumin (ALB) contents in colostrum. These parameters were also followed: calf's health, live weight, leucocyte (Lc) counts, T-lymphocyte (T-Ly) counts, contents of TPs, IgCs and ALBs in the blood serum of calves. Zinc concentrations were determined in colostrum, milk and calf blood serum. Our observations included 16 dairy cows in the seventh month of pregnancy in the second lactation and their calves in the winter feeding season. Eight experimental dairy cows were treated with the Zindep preparation in form of an injection to the neck muscles at a dose of 3 mg Zn/kg live weight in the mid-seventh month of pregnancy. Blood samples were taken from v. jugularis from all calves before their first drinking, on days 5, 15 and 30 of age. Colostrum, and/or milk samples were obtained by drawing of the colostrum or milk from the udder quarters within 60 minutes after parturition, on days 5 and 15 of lactation. Zn levels at birth were 16.48 +/- 2.67 mumol/l in experimental calves and 13.84 +/- 3.19 mumol/l in control calves. Zincaemia decreased slightly in both groups on days 5 and 15 of age, but it was insignificantly higher in calves coming from Zindep-treated dairy cows. Zn levels in the blood serum on the 30th day of age were 18.45 +/- 2.44 mumol/l in experimental animals and 15.73 +/- 3.11 mumol/l in control animals. Zn content in the colostrum of experimental cows was 2.40 +/- 0.42 mg/l and in the control it was 1088 +/- 0.52 mg/l (P < 0.05). On day 5 of lactation, Zn amounts in the milk of experimental dairy cows decreased to 0.95 +/- 0.12 mg/l and to 0.76 +/- 0.10 mg/l in the control (P < 0.01). Zn levels in the milk of experimental cows on day 15 of lactation were 0.95 +/- 0.13 mg/l and in the milk of control group they were 0.82 +/- 0.14 mg/l. Colostrum specific weight from zinc-treated cows was 1,067.86 +/- 0.75 g/cm3 and 1,056.8 +/- 13.53 g/cm3 in the control. TP and IgC concentrations were 137.81 +/- 38.11 g/l and 110.13 +/- 29.91 U ZST, respectively, in the colostrum of experimental group, and 105.98 +/- 32.02 g/l and 85.53 +/- 25.42 U ZST, resp., in control animals.(ABSTRACT TRUNCATED AT 400 WORDS)     

Pharmacokinetics and Dosage Regimen of Ceftriaxone in Buffalo Calves

The pharmacokinetics and dosage regimen of ceftriaxone were investigated in buffalo calves (n = 6) following a single intravenous administration of ceftriaxone (10 mg/kg). The elimination rate constant was 0.18 +/- 0.01 h(-1) and the elimination half-life was 3.79 +/- 0.09 h. The apparent volume of distribution (Vd(area)) was 1.40 +/- 0.01 L/kg and the total plasma clearance was 0.26 +/- 0.01 L/(kg h). Approximately 43% of total administered dose of ceftriaxone was excreted in urine within 8 h. To maintain a minimum therapeutic concentration of 1 microg/ml, a satisfactory intravenous dosage regimen of ceftriaxone in buffalo calves is 13 mg/kg repeated at 12 h intervals.     

Oral chloramphenicol dosage regimens in cats

Five adult domestic cats were each given three separate 3-day courses of chloramphenicol, using a different oral-dosage regimen each time. The regimens were: 120 mg/kg/day divided 8-hourly, 60 mg/kg/day divided 8-hourly, and 50 mg per cat every 12 h (25–40 mg/kg/day). The interval between successive courses was 3 weeks. On the third day of each course plasma samples were obtained at fixed intervals after dosing and were assayed chemically for chloramphenicol. The ranges from peak to trough chloramphenicol concentrations with each regimen were (values are means ± SEM): 63.8 ± 4.60 to 43.0 ± 3.32 μg/ml (120 mg/kg/day), 42.0 ± 3.63 to 24.7 ± 1.83 μg/ml (60 mg/kg/day), and 24.3 ± 1.72 to 7.5 ± 0.85 μg/ml (50 mg per cat 12-hourly). Because of these findings, previous toxicity studies, and the proposed therapeutic (effective and safe) concentration for chloramphenicol of 5–15 μg/ml, it is suggested that a regimen of 50 mg per animal every 12 h could be adequate for chloramphenicol therapy in cats of average size (2.5-3.9 kg) and should be evaluated clinically.     

Modification of the Pharmacokinetics and Dosage of Cefuroxime by Endotoxin-induced Fever in Buffalo Calves

The effect of endotoxin-induced fever on the pharmacokinetics and dosage regimen of cefuroxime was investigated in buffalo calves following a single intravenous dose of 10 mg/kg body weight. The fever was induced by intravenous administration of E. coli endotoxin at a dose of 1 g/kg body weight. The distribution and elimination half-lives were 0.100 h and 1.82 h, respectively, in healthy and 0.109 h and 2.28 h, respectively, in febrile buffalo calves. About 91% of the administered dose was excreted in the urine within 24 h. There was no effect of fever on the plasma protein binding of cefuroxime. The dosage regimen for intravenous administration of cefuroxime may be reduced in febrile conditions but the probability of this was only 0.3.     

Disposition and bioavailability of neomycin in Holstein calves

Pedersoli, W.M., Ravis, W.R., Jackson, J., Shaikh, B. Disposition and bioavailability of neomycin in Holstein calves. J. vet. Pharmacol. Therap. 17 , 5–11.
The disposition and absorption kinetics of neomycin were studied in healthy ruminating dairy calves ( n -6), approximately 3-months-old. The calves were treated with single intravenous (i.v.) (12 mg/kg), intramuscular (i.m.) (24mg/kg), oral (p.o.) (96 mg/kg) and repeated p.o. (96 mg/kg, b.i.d., 15½ days) doses of neomycin. A 3-week rest period was allowed between treatments A and B and B and C Baseline and serial venous blood samples were collected from each calf plasma concentrations of neomycin were determined by a high performance liquid chromatography procedure. The resulting data were evaluated by using compartmental pharmacokinetic models and nonlinear least squares regression analysis. The mean of some selected parameters were t ½λ3 7.48 ± 2.02 h, Cl_t= 0.25 ± 0.04 L/h/kg, V _d(ss)= 1.17 ± 0.23 L/kg, and MRT = 4.63 ± 0.87 h for the i.v. data and t _½= 11.5 ± 3.8 h, MRT _abs= 0.960 ± 1.001 h, F = 127 ± 35.2%, and Cl_t/F = 0.199 ± 0.047 L/h/kg for the i.m. data, respectively. Only one calf absorbed neomycin to any significant degree (F = 0.0042) after a single p.o. dose. Selected mean parameters determined after repeated oral dosing were: F = 0.45 ± 0.45%, C_max= 0.26 ± 0.37 g/ml, and t_max= 2.6 ± 2.9 h. Terminal half-lives determined for the i.v. and i.m. treatments were considerably longer than those reported previously in the literature.     

Leukocyte changes and interferon production in calves injected with hydrocortisone and infected with infectious bovine rhinotracheitis virus.

Correlations between leukocyte counts and serum interferon titers were determined in calves given hydrocortisone (HC) and infectious bovine rhinotracheitis (IBR) virus. Calves were injected with either 1 mg or 3 mg of HC/kg of body weight every 8 hours for a total of 9 injections each. Control calves were given placebo injections. Viral inoculation was given IV 10 hours after the 1st dose of HC or placebo was given. By the time of viral inoculation, all calves injected with HC had developed neutrophilia, and the calves injected with 3 mg of HC also developed leukocytosis, lymphopenia, and eosinopenia; total leukocyte counts in calves injected with 1 mg of HC were increased, but not as much as in other HC-treated calves. Leukocyte counts in calves given placebo remained essentially unchanged before viral inoculation. At 1 day after IBR virus was inoculated, the number of circulating lymphocytes in HC-treated calves and control calves was decreased by more than 50%, on the average, of the counts taken before the HC injections or inoculation of virus. A significant negative correlation existed between the numbers of circulating lymphocytes and serum interferon titers at 1, 2, and 3 days after inoculation with IBR virus. The interferon response of calves undergoing lymphocyte suppression due to HC was not impaired, but was enhanced.     

Concentrations of tinidazole in gingival crevicular fluid and plasma in dogs after multiple dose administration

Tinidazole 15 mg/kg was administered to eight Beagle dogs with gingivitis or periodontitis twice daily for 3 days. Tinidazole concentrations in blood and gingival crevicular fluid (GCF) were measured 1,3,6 and 9 h after the morning dose each day. The concentration of tinidazole was determined by high performance liquid chromatography (HPLC). The mean concentration of tinidazole in GCF for each dog ranged from 6.05 to 9.32 αg/mL at different time points after the first dose, and on the first day the highest concentration was observed 6 h after the drug administration. Tinidazole concentrations were 34 ± 4%-72 ± 9% (mean ± SEM) of simultaneous plasma concentration. At steady-state, on the third treatment day, the mean tinidazole concentrations in GCF ranged from 6.68 to 13.1 μg/mL, i.e. 44 ± 6%-75 ± 25% of the corresponding concentrations in plasma. Tinidazole concentration in GCF exceeded the MIC values for putative path-ogenic periodontal bacteria and it is concluded that, when indicated, tinidazole could be used for chemotherapy of periodontitis in dogs.     

Effect of sulfadimethoxine-ormetoprim in the treatment of calves with induced Pasteurella pneumonia

The efficacy of sulfadimethoxine (SDM)-ormetoprim (OMP) was evaluated in calves with induced Pasteurella pneumonia. A dose-titration study comparing 3 doses of SDM-OMP was performed to determine the optimal dose. Treatments included: group 1--nontreated controls; group 2--33 mg of SDM-OMP/kg of body weight, orally on day 1 and 17 mg/kg on days 2 to 5; group 3--66 mg of SDM-OMP/kg, orally on day 1 and 33 mg/kg on days 2 to 5; group 4--99 mg of SDM-OMP/kg, orally on day 1 and 50 mg/kg on days 2 to 5; and group 5--11 mg of oxytetracycline/kg, IV daily for 4 days. Group-2 calves responded to treatment as well as did group-5 calves. Group-4 calves responded the same as did group-3 calves. However, group-2 calves did not respond as well as did groups 3, 4, and 5 calves.     

Comparative therapeutic effect of toltrazuril, sulphadimidine and amprolium on Eimeria bovis and Eimeria zuernii given at different times following infection in buffalo calves (Bubalus bubalis)

We compared the therapeutic effect of three anticoccidial drugs (toltrazuril, sulphadimidine and amprolium) in buffalo (Bubalus bubalis) calves experimentally infected with Eimeria bovis (E. bovis) and E. zuernii oocysts (3 x 104oocyst/calf). Buffalo calves (1.5-4 month old, 70-kg body weight) were randomly allocated into 3 groups (9 calves each). Group T was experimentally infected with oocysts and treated with toltrazuril (20 mg/kg BW twice orally at a 1-week interval). Group S was experimentally infected with oocysts and treated with sulphadimidine (125 mg/kg injected IM followed by half dose for 4 successive days). Group A was experimentally infected with oocysts and treated with amprolium (50 mg/kg orally for 7 successive days). Each group had three subgroups (three calves/subgroup) to represent timing of the drug administration: 1st day of coccidia infection (FD), onset of clinical signs of coccidiosis (CC), and onset of oocyst shedding into the faeces (OS). Clinical signs, body-weight gain (BWG) and number of oocysts per gram feces (OPG) were monitored daily for 35 days post-infection (DPI). The OPG were reduced (but the BWG was not different) in the T calves compared to S and A calves. Within the same group, treatment from the 1st day of infection reduced the OPG and increased the BWG compared to the later treatment timings.     

Effects of subcutaneous injections of a long acting moxidectin formulation in grazing beef cattle on parasite fecal egg reduction and animal weight gain

Trials were conducted in Arkansas, Idaho, Illinois and Wisconsin using a common protocol to evaluate effectiveness and safety of a long acting (LA), oil-based injectable formulation of moxidectin in beef cattle grazing spring and/or summer pastures. At each site, 150 cattle (steers and/or heifers) were blocked based on pretreatment fecal strongyle egg counts (EPG) and then randomly assigned to treatments within blocks. Presence of naturally acquired parasitic infections, confirmed by presence of parasite eggs in feces, was a prerequisite for study enrollment. Within each block of three animals, two received moxidectin LA injectable on day 0 at a dosing rate of 1.0 mg moxidectin/kg b.w. into the dorsal aspect of the proximal third of the ear, and one received a placebo control treatment. Cattle were weighed before treatment and on day 55 or 56 (55/56) after treatment. Fecal samples were also collected from 10 randomly selected blocks of animals at each site on days 14, 28 and 55/56 for EPG quantification. Average daily gain (ADG) was computed over the posttreatment period. Data pertaining to ADG and EPG were combined across sites and analyzed by mixed model analysis of variance to assess the fixed effect of treatment and random effects of site, block within site and the treatment by site interaction. Compared to placebo-treated controls, the geometric means of fecal EPG counts from cattle treated with moxidectin LA injectable were reduced 99.8% 14 days after treatment, 99.1% 28 days after treatment and 96.7% 55/56 days after treatment. Rate of weight gain by cattle treated with moxidectin LA injectable was 0.59 kg/day, or 23% (0.11 kg/day) more than placebo-treated controls (P<0.05). None of the cattle treated with moxidectin LA injectable exhibited signs of macrocyclic lactone toxicosis. Summarized across all study sites, proportions of cattle that received concurrent therapeutic treatments were similar among treatment groups. Study results demonstrate that moxidectin cattle LA injectable administered at a dosing rate of 1.0 mg moxidectin/kg b.w. to grazing beef cattle was effective and safe.     

Serum chloramphenicol concentrations in preruminant calves: a comparison of two formulations dosed orally

Serum concentrations of chloramphenicol were determined after oral doses (55 mg/kg body weight) were administered to 7–9 day old Holstein-Friesian calves. Chloramphenicol in an oral solution produced greater serum concentrations than did an equivalent dose of chloramphenicol in capsules ( P <0.005). A second dose of each formulation administered 12 h after the first dose elevated serum chloramphenicol concentrations significantly ( P <0.001). The average serum chloramphenicol concentration exceeded 5 μg/ml of serum 1 h after administration of the solution compared with 4 h for the capsules. Average serum chloramphenicol concentration was greater than 5 μg/ml for at least 12 h after the dose was administered for both formulations. Of the eight calves receiving repeat doses of chloramphenicol, seven (87.5%) developed diarrhea in 76 ± 8.6 h. Six of the eight calves (75%) died during or shortly after the period of chloramphenicol administration.     

A field study on the efficacy of doramectin against strongyles and its egg reappearance period in horses

The aim of the present study was to determine the efficacy and the so-called "egg reappearance period" (ERP) of doramectin in horses naturally infected with strongyles during a period of 34 weeks. A group of yearlings of 10 animals was treated intramuscularly with doramectin at a dose rate of 0.2 mg/kg bodyweight (BW) at the begin of the grazing season. To obtain comparable data, another group of yearlings (n = 10) was treated orally with ivermectin at a dose rate of 0.2 mg/kg BW. Individual faecal samples were examined for strongyle egg counts per gram of faeces (EPG) in two-week intervals. Twelve weeks later, a second treatment was given in both groups with the respective anthelmintic followed by a third treatment when the group mean egg count reached > or = 200 EPG. The efficacy of doramectin was > or = 96 % and that of ivermectin 100%, based on the mean egg counts two weeks post treatments (wpt). The highest and the lowest extensity of the efficacy (average values) for doramectin were 90% and 41% two and ten wpt, respectively, whereas these values for ivermectin differed from 100% (two wpt) to 24.3% (eight wpt). The ERP was found to be 10 and 8 weeks for doramectin and ivermectin, respectively.     

The effect of long-term exposure to phosphamidon on the ruminal microorganisms and circulating carboxylesterase ofBubalus bubalis

The effect of long-term exposure to the organophosphate insecticide phosphamidon on the ruminal microorganisms and serum carboxylesterase of buffalo calves was investigated. Oral administration of phosphamidon in doses of 0.25 and 0.5 mg/kg per day for 120 days caused significant inactivation of carboxylesterase activity (16–32%) without eliciting any intoxicating signs apart from mild intermittent diarrhoea in the animals receiving the higher dose. The higher dose also produced a significant reduction in the total number of rumen protozoa (16–24%). However, the insecticide had no discernible effect on the total bacterial count or pH of the rumen liquor.     

The kinetic disposition and dosage regimen for carbenicillin in buffalo calves

The distribution half-life, elimination half-life, apparent volume of distribution and total body clearance of carbenicillin in healthy buffalo calves following a single intravenous administration (50 mg/kg) were 0.057±0.005 h, 1.688±0.11 h, 0.185±0.021 L kg^-1 and 75.97±6.519 ml kg^-1 h^-1 respectively. A satisfactory dosage regimen for carbenicillin in buffalo calves was calculated to be 56 mg/kg followed by 52 mg/kg body weight repeated at 6 h intervals.     

Pharmacokinetic disposition and plasma protein binding (in vitro) of chloramphenicol in Bubalus bubalis I*

Eleven buffalo calves (Bubalus bubalis) of 1-1 1/2 years of age and weighing between 64 and 174 kg were given chloramphenicol at the dose rates of 10 and 20 mg/kg body weight. Pharmacokinetic parameters were determined from the plasma levels. The median elimination half-life was estimated to be 2.95 h and the median volumes of distribution were 1.1667 litres/kg with the 10 mg/kg dose and 0.9699 litres/kg with the 20 mg/kg dose. The median metabolic clearance rates were 288.30 and 234.13 ml/h/kg, respectively. From the average plasma concentrations obtained with the 20 mg/kg i.v. dose, it was considered necessary to repeat the drug by the i.m. route with the same dose (four calves) which resulted in prolonging the therapeutic concentration (> 5 μg/ml) until 18 h. At therapeutic concentrations, about 60% of the drug was bound to plasma proteins. Using the overall elimination rate constant (0.2354 h^-1) and the apparent specific volume of distribution (0.97 litres/kg), different dosage regimens were calculated so as to obtain plasma concentrations (C_p min) of 2, 5 and 10 μg/ml.