Long-term prevention of estrus in the bitch and queen using chlormadinone acetate

Estrus was prevented with weekly oral administration of 2 mg chlormadinone acetate for 2.0 to 9.8 y in bitches and queens. Abnormalities, including mammary or uterine disorders, or both, were noted in 7 out of 14 bitches and 9 out of 24 queens during this long-term treatment.     

Pour-on method of administering chlormadinone acetate for estrus synchronization in heifers

Experiments with chlormadinone (Bovisynchron) on 380 heifers and 60 cows showed that the drug was absorbed following pour-on application. A volume of 2 ml was rubbed into the skin of the back anterior to the sacrum, once daily for 15 days. Residual amounts were removed 24 hours after the final application by washing the hair coat with dimethyl sulphoxide solution. Insemination was performed at the same time as after oral administration. The pour-on method was particularly suitable for heifers and cows out at pasture.     

Fertility of bitches in which estrus was prevented with implantations of chlormadinone acetate for four years

The recurrence of estrus and fertility after removal of a subcutaneous chlormadinone acetate implant (CMA-I) administered to prevent estrus for 4 years, was investigated in 8 female dogs and the results compared with those for 4 untreated female dogs (control group). The sex hormones present during the estrous cycle were also investigated. There were no significant differences in the estrous cycle after removal of the implant between the CMA-I-treated group and the control group. However, although conception was achieved after mating and no uterine diseases developed in the control group, only 5 (4 dogs, 41.7%) of the 12 cases (6 dogs) in which mating took place at the second to fourth estrus after the removal of CMA-I resulted in pregnancy in the CMA-I-treated group. Furthermore, 6 (75.0%) of the 8 dogs in the CMA-I-treated group developed uterine diseases including pyometra or hydrometra. There were no significant differences in plasma progesterone, LH and prolactin levels between the non-pregnant and pregnant dogs in the CMA-I-treated group or control group. These results suggest that long-term implantation of CMA-I affects fertility after the implant is removed.     

Concentration of estrone, estradiol and estriol in the blood of pregnant sheep after induction of estrus with chlormadinone acetate and medroxyprogesterone acetate]

The radioisotopic method of 131J-labelled albumin was employed to determine the distribution of acidic proteinase activity in some organs and tissues of chickens. The highest enzymatic activities were found in intestine wall, in pancreas, and in liver. Considerably lower activities were ascertained in kidneys, brain, lungs, and heart. The different proportions of these enzymes in homogenates and supernatant fractions (106 000 g) testify to a lack of uniformity in the solubility of cathepsins in the organs tested. The tested organs, with the exception of pancreas, did not show any enzymatic activity of neutral proteinases.     

Oestrus control in bitches with chlormadinone acetate

A clinical study of oestrus control in bitches with chlormadinone acetate (CMA) is reported. The commercial 1-0 per cent crystalline suspension of CMA was injected subcutaneously at a dose of 3 mg/kg, or somewhat lower for the largest animals. Treatment was initiated always in anoestrus and was repeated twice annually for as long as requested. The longest, 9-year, period of anoestrus was achieved by twenty repeated treatments. A total of 2,471 treatments were given to 568 bitches (an average of 4-4 treatments per bitch) during a period of over 10 years, with an efficacy of 98 per cent. The incidence of false pregnancy, uterine inflammatory disorders and mammary nodules in the treated group were compared to those of an age-related control group of 487 bitches that did not receive hormonal treatment. A lower incidence of false pregnancy and the two clinical entities was observed in the group of treated animals. It is concluded that CMA can be used safely and reliably for oestrus control in bitches and is therefore, an appropriate alternative for ovariohysterectomy.     

Megestrol acetate for estrus postponement in the bitch.

Megestrol acetate was given orally to 389 bitches in early proestrus, at a dosage of 2.2 mg/kg (1 mg/lb) per day for 8 days. Estrus was suppressed in 357 (92%) of the bitches. Additionally, 119 bitches in anestrus were given the drug at the rate of 0.55 mg/kg (0.25 mg/lb) per day for 32 days. Estrus was suppressed in 115 (98%) of these bitches. Adverse effects were minimal. Pyometra developed in 3 (0.8%) of the 389 bitches treated in early proestrus. The drug also was given to 19 bitches at the rate of 0.55 mg/kg/day for 32 days, regardless of the stage ofting at the 1st posttreatment estrus and 4 after mating at the 2nd posttreatment estrus. Litter size, success in rearing pups, and sex ratios were not significantly different from these factors in 53 litters from untreated bitches.     

Pharmacokinetics of intravenously and orally administered pyrimethamine in horses.

Single-dose pharmacokinetic variables of pyrimethamine were studied in horses. Pyrimethamine (1 mg/kg of body weight) was administered IV and orally to 6 adult horses, and plasma samples were obtained at frequent intervals thereafter. Plasma pyrimethamine concentration was assayed by gas chromatography, and concentration-time data were analyzed, using a pharmacokinetic computer program. The IV and oral administration data were best described by 3-compartment and 1-compartment models, respectively. The median volume of distribution at steady state after IV administration was 1,521 ml/kg and the median elimination half-time was 12.06 hours. Mean plasma concentration after oral administration fluctuated between a maximal concentration of 0.18 microgram/ml and 0.09 microgram/ml (24 hours after dosing). Bioavailability after oral administration was 56%.     

Regulation of stress-free nonlaying periods using chlormadinone acetate]

Nonlaying intervals were induced in 6 group of 30 hens with chlormadinone acetate (CAP), with a 7th groups serving as a control. 3 groups were treated for 10 days and 3 for 20 days, each group getting a different dosage of CAP. 1.2% of the hens were lost per month in the control group, with losses in the other 6 groups ranging from .6 to 1.7%/month. The length of the nonlaying period corresponded in 5 groups to the dosage and length of CAP treatment. The groups treated with the lowest daily dosages in the 10- and 20-day groups did not experience a complete nonlaying interval. The CAP treatment caused thickening of the egg shells but did not alter the weight of the eggs. The hens treated with CAP lost most of their feathers during the treatment. The longer, more concentrated dosage of CAP caused egg production to decrease more quickly, a prolonged nonlaying interval, and a higher rate of egg production following the nonlaying interval.     

Pharmacokinetic evaluation of enrofloxacin administered orally to healthy dogs.

Enrofloxacin was administered orally to 6 healthy dogs at dosages of approximately 2.75, 5.5, and 11 mg/kg of body weight, every 12 hours for 4 days, with a 4-week interval between dosage regimens. Serum and tissue cage fluid (TCF) concentrations of enrofloxacin were measured after the first and seventh treatments. The mean peak serum concentration occurred between 1 and 2.5 hours after dosing. Peak serum concentrations increased with increases in dosage. For each dosage regimen, there was an accumulation of enrofloxacin between the first and seventh treatment, as demonstrated by a significant (P = 0.001) increase in peak serum concentrations. The serum elimination half-life increased from 3.39 hours for the 2.75 mg/kg dosage to 4.94 hours for the 11 mg/kg dosage. Enrofloxacin accumulated slowly into TCF, with peak concentrations being approximately 58% of those of serum. The time of peak TCF concentrations occurred between 3.8 hours and 5.9 hours after drug administration, depending on the dosage and whether it was after single or multiple administrations. Compared with serum concentrations (area under the curve TCF/area under the curve serum), the percentage of enrofloxacin penetration into TCF was 85% at a dosage of 2.75 mg/kg, 83% at a dosage of 5.5 mg/kg, and 88% at a dosage of 11 mg/kg. All 3 dosage regimens of enrofloxacin induced continuous serum and TCF concentrations greater than the minimal concentration required to inhibit 90% (MIC90) of the aerobic and facultative anaerobic clinical isolates tested, except Pseudomonas aeruginosa.(ABSTRACT TRUNCATED AT 250 WORDS)