Variation in cardiac markers and electrocardiographic alterations in young calves naturally infected with bovine tropical theileriosis

The present study was designed to assess the deleterious effects of bovine tropical theileriosis on the cardiovascular system and the consequent myocardial involvement in young calves. Myocardial effects in parasitic diseases are often neglected. Hemolytic anemia, associated secondary hypoxia, and vasculitis are cardinal features of bovine theileriosis. In the present study, electrocardiogram (ECG) alongside serum cardiac troponin I (cTnI) and creatinine phosphokinase-myocardial band (CPK-MB) concentrations were analyzed in infected, treated, and control groups of young calves. Non-significant alterations were noticed in ECG. However, certain signs like sinus tachycardia, first-degree AV block, atrial premature complex, left atrial hypertrophy, and right atrial hypertrophy were found on consistent basis in infected calves. A significant increase in the serum concentration levels of cTnI and CPK-MB was noticed in infected calves followed by significant fall in both these biomarkers post treatment. cTnI and CPK-MB can definitely be used as myocardial markers in theileriosis-affected animals.     

Lowered vaccine dose for immunisation of calves against tropical theileriosis usingTheileria annulata lymphoblasts

Tropical Animal Health and Production - Bovine tropical theileriosis is of high incidence in calves below 2 months old in India. TheTheileria cell culture vaccine evolved by the Punjab Agricultural...     

Influence of experimentally induced theileriosis (Theileria annulata) on the pharmacokinetics of a long-acting formulation of oxytetracycline (OTC-LA) in calves

The effects of experimental Theileria annulata infection on the i.m. (20 mg/kg) pharmacokinetics of oxytetracycline were investigated in crossbred calves. The serum concentration-time curves of oxytetracycline (OTC-LA), before and after experimental infection, were best described by a one-compartment open model. The experimental infection by subcutaneous administration of ground-up tick supernate (GUTS), equivalent to 30 Hyalomma anatolicum anatolicum ticks infected with Theileria annulata, produced a clear temperature rise and signs of clinical disease in calves. Subsequently, haemoglobin, packed cell volume, total leucocyte count and serum Cu, Fe and Zn concentrations decreased after infection. The absorption and elimination half-lives (t1/2 Ka and t1/2 Ke), mean absorbance time (MAT), time to peak concentration (Tmax), mean residence time (MRT), area under the serum concentration time curve (AUC infinity) and the bioavailability (F) were significantly (P < 0.05) decreased. The peak serum concentration (Cmax), however, remained unchanged after infection. These changes may necessitate alterations in the dosage regimen of oxytetracycline used to treat Theileria annulata infections in cattle under field conditions.     

Treatment of Moraxella bovis infections in calves using a long-acting oxytetracycline formulation

George, L.W. & Smith J.A. Treatment of Moraxella bovis infections in calves using a long-acting oxytetracycline formulation. J. vet. Pharmacol. Therap. 8, 55–61.
Studies were undertaken to determine the effectiveness of an oxytetracycline HCl formulation for the prophylaxis and treatment of chronic Moraxella bovis ocular infections in calves. Two separate experiments were performed. For the first, calves were separated into two groups and the eyes were infected with M. bovis. The eyes of these calves were observed and cultured for 37 consecutive days. On the 37th and 40th day, each of the five calves were treated intramuscularly with the drug (20 mg/kg of body weight). The other five calves (second group) remained untreated as controls. The cultures from the five treated calves were negative after the first antibiotic administration and remained so for 14 days. M. bovis was isolated from each eye of the control calves at least once during that time. None of the antibiotic-treated calves was completely resistant when reinfected with M. bovis. For the second experiment, calves were given a prophylactic administration of the formulation and were then infected with M. bovis 48 ( n = 4 calves) or 72 ( n = 4 calves) h later. These treatments resulted in a lower incidence of keratoconjunctivitis and a decreased duration of bacterial shedding, as compared to controls ( n = 8 calves), but did not completely prevent the occurrence of disease or the establishment of ocular infections.
Lisle W. George, Department of Medicine, School of Veterinary Medicine, University of California, Davis, CA 95616, U.S.A.     

Use of long-acting oxytetracycline against pasteurellosis in lambs

The efficacy of long-acting oxytetracycline in the control of pneumonic pasteurellosis in lambs was tested on seven Scottish farms. After laboratory confirmation of pasteurella-related deaths in lambs, half the lambs in each flock were given long-acting oxytetracycline (20 mg/kg intramuscularly) and half were left untreated. On three farms a single treatment was given and on four farms two doses were administered four days apart. Eighteen of the 878 control lambs died as a result of confirmed Pasteurella haemolytica pneumonia compared with one of the 878 treated lambs. In addition nine of the control lambs were diagnosed clinically to have pasteurellosis which responded to treatment with oxytetracycline. None of the treated lambs were seen to be ill during the trial.     

Non-specific immunization against bovine tropical theileriosis (Theileria annulata) using killed Corynebacterium parvum

Killed Corynebacterium parvum was used as an adjuvant for the production of non-specific resistance against Theileria annulata in cattle. Groups of cross-bred (Bos indicus X Bos taurus) calves were administered C. parvum adjuvant subcutaneously and were then challenged with T. annulata-infected ticks on 45, 60 or 90 days later. The challenge caused mild reactions in the protected calves. None of the 10 immunized calves died due to theileriosis, whereas all three paris of susceptible control calves died due to theileriosis. It appears from this pilot study that cattle can be protected non-specifically with C parvum adjuvant against T. annulata.     

Efficacy of long-acting oxytetracycline for the prevention of tick-borne fever in calves

Twenty-six calves which had not previously grazed tick-infested pasture were divided into two equal groups. On May 26, 1988 (day 0) they were turned out into a field of rough grazing where cases of redwater fever had occurred the previous spring. Seven, 14, 21 and 28 days after the start of the trial the animals in one group each received an intramuscular injection of 20 mg/kg bodyweight of long-acting oxytetracycline. During the 60 days of the trial the animals received a severe tick-borne fever challenge, in some cases combined with a redwater fever challenge. An unforeseen complicating factor was the presence of animals persistently infected with bovine viral diarrhoea virus, present in almost equal numbers in both groups. At the end of the trial the treated group weighed on average 16 kg more than the control group, a difference which was attributed to the suppression of tick-borne fever by oxytetracycline.     

Treatment of acute ocular Moraxella bovis infections in calves with a parenterally administered long-acting oxytetracycline formulation

Acute ocular Moraxella bovis infections were induced in the UV-irradiated eyes of 10 calves. Eight calves developed corneal ulcers in at least 1 eye and were used for the treatment experiment. One randomly selected group of 4 calves with corneal ulcers and M bovis infections in 7 eyes was given a long-acting oxytetracycline formulation in 2 IM dosages of 20 mg/kg of body weight each, 72 hours apart. The other 4 calves with corneal ulcers in 6 eyes and M bovis in all 8 eyes served as nontreated controls. Bilateral ocular cultures were obtained and clinical observations were made daily for 20 days after treatment. After administration of the long-acting drug, new ulcers did not develop in the treated calves, whereas 5 new ulcers developed in the control-group calves during this time. The average durations of increased lacrimation/ulcerated eye were 2 and 12 days after treatment in the treatment and control groups, respectively; the average durations of blepharospasm were 3 and 8 days, respectively. Moraxella bovis was not isolated from any of the eyes of the treatment-group calves for the first 6 days after the antibiotic was administered, but was isolated from 1 eye of 1 treated calf on posttreatment day 7 and daily thereafter, for a total of 14 positive cultures of 160 ocular cultures obtained from the treatment-group calves after treatment. The bacterium was isolated from all eyes and from 144 of 160 cultures from the control-group calves during this time.     

Serum pharmacokinetics of oxytetracycline in sheep and calves and tissue residues in sheep following a single intramuscular injection of a long-acting preparation

The pharmacokinetics of a long‐acting oxytetracycline (OTC) formulation (Liquamycin® LA‐200®) injected intramuscularly (i.m.) at a dose of 20 mg/kg were determined in four calves and 24 sheep to determine if the approved label dose for cattle provided a similar serum time/concentration profile in sheep. The AUC for the calves was 168±14.6 (μg ? h/mL) and was significantly less than the AUC for sheep (209±43 μg ? h/mL). Using the standard two‐stage approach and a one‐compartment model, the mean Cmax for the calves was 5.2±0.8 μg/mL, and for the sheep was 6.1±1.3 μg/mL. The mean terminal phase rate constants were 0.031 and 0.033 h, and the Vdss were 3.3 and 3.08 L/kg for the calves and sheep respectively. Analysis of the data using the standard two‐stage approach, the naive pooled‐data approach and a population model gave very similar results for both the cattle and sheep data. Sheep tissue residues of OTC in serum, liver, kidney, fat, muscle and injection site were measured at 1, 2, 3, 5, 7 and 14 days after a single i.m. injection of 20 mg/kg OTC. Half‐lives of OTC residues in the tissues were 38.6, 33.4, 28.6, 25.4, 21.3, and 19.9 h for injection site, kidney, muscle, liver, mesenteric fat and renal fat, respectively. The ratio of tissue to serum concentration was fairly consistent at all slaughter times, except for the fat and injection sites. The mean ratios were 1.72, 4.19, 0.11, 0.061, 0.84 and 827 for the liver, kidney, renal fat, mesenteric fat, muscle and injection sites, respectively. The tissue concentrations of OTC residues were below the established cattle tolerances for OTC in liver (6 p.p.m.), muscle (2 p.p.m.) and kidney (12 p.p.m.) by 48 h, and in injection site muscle by 14 days after the single i.m. injection of 20 mg/kg.     

Serum oxytetracycline concentrations in African elephant (Loxodonta africana) calves after long-acting formulation injection.

Serum oxytetracycline pharmacokinetics were studied in 18 African elephant (Loxodonta africana) calves. Each elephant received separate injections of oxytetracycline at approximately 18 mg/kg i.m. and 8 mg/kg i.v. in a cross-over study. Blood samples were drawn at 0, 24, 48, 72, and 96 hr postinjection. An additional sample was drawn 110 hr before the animals were reinjected in the cross-over study and a final blood sample was drawn 48 hr after the second dose. No lameness or stiffness was observed following i.m. injections. Serum oxytetracycline concentrations >0.5 microg/ml were present 48 hr after initial dosing for all elephants (i.m., i.v., high or low dosage). Only elephants given the high i.m. dosage (18 mg/kg) maintained levels >0.5 microg/ml 72 hr postinjection. No significant difference in serum oxytetracycline concentration with time was observed between the groups given different i.v. dosages. These studies demonstrated that quantifiable serum oxytetracycline concentrations can be maintained in young African elephants with a low-dosage multidose i.m. regimen.     

Correlation between maternal serum antibodies and protection against bovine rotavirus diarrhea in calves

The correlation between maternal serum antibodies in beef calves at 2 days old and protection against diarrhea induced by natural bovine rotavirus (BRV) infection was examined. Virus neutralizing (VN) antibody titers against BRV in sera from calves that developed diarrhea by BRV infection within 14 days of age (BRV-diarrheal calves) were significantly lower than those from calves that had no diarrhea. In the BRV-diarrheal calves, a positive correlation was found between the VN antibody titers and age of the onset of diarrhea. There were negative correlations between the VN antibody titers and duration of the diarrhea, VN antibody titers and cumulative diarrhea scores, and the VN antibody titers and duration of virus shedding. These results suggest that the VN antibody titers against BRV in newborn calf serum could be an indicator of protection against BRV-induced diarrhea.     

A comparison of prophylactic efficacy of tilmicosin and a new formulation of oxytetracycline in feedlot calves

Two replicated-pen field studies were performed under commercial feedlot conditions in western Canada to compare the administration of long-acting oxytetracycline at 30 mg/kg body weight (BW) versus tilmicosin at 10 mg/kg BW to feedlot calves upon arrival at the feedlot. Ten thousand nine hundred and eighty-nine, recently weaned, auction market derived, crossbred beef steer and bull calves were randomly allocated upon arrival at the feedlot to one of 2 experimental groups as follows: oxytetracycline, which received intramuscular long-acting oxytetracycline (300 mg/mL formulation) at a rate of 30 mg/kg BW; or tilmicosin, which received subcutaneous tilmicosin (300 mg/mL formulation) at a rate of 10 mg/kg BW. There were 20 pens in each experimental group. In Study 1 and in the combined analysis, the initial undifferentiated fever (UF) treatment rate was significantly (P < 0.05) higher in the oxytetracycline group as compared with the tilmicosin group. There were no significant (P > or = 0.05) differences in first UF relapse, second UF relapse, third UF relapse, overall chronicity, overall rail, overall mortality, bovine respiratory disease (BRD) mortality, hemophilosis mortality, arthritis mortality, or miscellaneous mortality rates between the experimental groups in either study or in the combined analysis. In addition, there were no significant (P > or = 0.05) differences in initial weight, final weight, weight gain, days on feed, daily dry matter intake, average daily gain, or the dry matter intake to gain ratio between the experimental groups in either study or in the combined analyses. In the economic analysis, there was a net economic advantage of $5.22 CDN per animal in the oxytetracycline group, due to a lower prophylactic cost, even though the UF therapeutic cost was higher.     

Efficacy of long-acting oxytetracycline alone or combined with streptomycin in the treatment of bovine brucellosis

Twenty-nine Brucella abortus culture-positive cows were treated with a long-acting oxytetracycline (20 mg/kg of body weight, IM) alone or combined with streptomycin (25 mg/kg, IM or IV) or were re-treated with the same product. There appeared to be a synergism by the 2 drugs. Of 21 courses of treatment with the combined antibiotics, 14 (67%) were considered successful. Only 3 of 14 (21%) were successful using oxytetracycline alone. The period from onset of therapy to cessation of shedding in udder secretions was variable. Four cows that ceased shedding were culture-positive in tissues taken at slaughter. The titers on tube agglutination and complement-fixation tests were of limited value in short-term evaluations of therapeutic regimens.     

Preventive treatment against toxocarosis in bovine calves.

Treatment of bovine calves 10-16 days old with an anthelmintic which is effective against immature Toxocara vitulorum killed the parasites, there was no new infection and recontamination of the environment was precluded. When the management of the program was delegated to the livestock officers, approximately 3% of calves scheduled for treatment developed patent infections. The prevalences of toxocarosis on the different farms were correlated with annual rainfall, probably because the longer dry periods associated with lower rainfall killed infective eggs in the environment. The treatment schedules prevailing before the study commenced were ineffective. The prevalence of toxocarosis in the bovine calves on farms in the area with an annual rainfall of about 1000 mm was lower than that in buffalo calves studied previously in the same area.     

Use of long-acting oxytetracycline in the immunisation of cattle against Babesia bovis and B bigemina

Forty Friesian one-year-old calves were vaccinated simultaneously with live Babesia bovis and B bigemina vaccines. Three groups of 10 calves each were treated with two, three or four doses of 20 mg kg-1 long-acting oxytetracycline (OTC/LA) at six- to seven-day intervals starting from day 6 after vaccination. Ten animals remained untreated. The treated calves showed considerably fewer days of patency and higher packed cell volumes than the vaccinated untreated calves. All calves developed serum antibodies to both parasites following vaccination. Five months later the 40 vaccinated and 30 new calves were challenged with syringe-transferred virulent parasites of both species. The vaccinated calves showed no parasites or clinical manifestations while calves of the new group exhibited severe clinical babesiosis. These results show that when OTC/LA is administered following anti-babesial vaccination, parasitaemia and red blood cell destruction are significantly reduced without, however, inhibiting the development of immunity.