Induction of an LH surge and ovulation by buserelin (as Receptal) allows breeding of weaned sows with a single fixed-time insemination.

The aim of this study was to demonstrate successful breeding of sows with a single fixed-time insemination following ovulation induction by buserelin, a GnRH analogue. In a first step, the optimal dose of buserelin (6, 10, or 16 µg) injected at 77 hours after weaning was determined in weaned sows (N = 15, 11, and 12, respectively) using its ability to induce an LH surge of similar magnitude as in control sows (N = 15) and induce ovulation. In 29/38 treated sows (76%), ovulation was induced and synchronized between 32 and 44 hours after injection, and the proportion of females ovulating during this time window was similar between groups at 73%, 73%, and 83% (6, 10, or 16 µg, respectively). Interestingly, whereas ovulation of 100% multiparous sows was induced and synchronized in the 32 to 44 hours posttreatment time window, successful induction was achieved in a lower proportion of primiparous sows (50%, 50%, and 67% following 6, 10, or 16 µg, respectively), the dose effect being nonsignificant. The magnitude of the LH surge was similar between control and treated sows, irrespective of the buserelin dose injected. Neither ovulation rate nor the number of good embryos on Day 5 postovulation differed between groups. Interestingly, the frequency of follicular cysts at slaughter was significantly affected by treatment (P < 0.05), being minimal and maximal in sows treated with 10 or 6 µg buserelin, respectively. In a second step, 419 sows from commercial herds in Spain, Germany, and France were randomly allocated to a control or treated group. The control sows were inseminated twice 12 ± 4 hours apart once estrus was detected. Treated sows received 10 µg buserelin at 86 ± 3 hours after weaning and were inseminated once 30 to 33 hours later. Farrowing rate of treated sows (87%, 166/192) was similar to that of control sows (84.5%, 169/200). Litter size was also similar between treated and control sows (13.6 ± 3.8 vs. 13.7 ± 3.2). In multiparous sows, neither duration of lactation nor magnitude of the fat loss during lactation significantly affected treatment effects. It is concluded that ovulation of weaned multiparous sows can be tightly synchronized by buserelin (10 µg) administration at 86 hours postweaning. This allows breeding once at a fixed time following buserelin injection while maintaining reproductive performance at a level similar to that of sows bred twice during estrus.

Efficacy and safety of a new 450 mg/ml florfenicol formulation administered intramuscularly in the treatment of bacterial bovine respiratory disease.

The objective of the study was the safety and efficacy evaluation of a new 450 mg/ml florfenicol formulation in the treatment of naturally occurring respiratory disease when administered intramuscularly, compared with a positive control group treated with the well-established 300 mg/ml formulation. A total of 174 calves, selected from five sites in France and Spain, aged from 1 to 17 months, showing severe signs of respiratory disease, were randomly assigned to treatment with either the 300 mg/ml (3 ml/45 kg; Nuflor; MSD Animal Health) or 450 mg/ml (2 ml/45 kg; Nuflor Minidose; MSD Animal Health) florfenicol formulation, both administered intramuscularly twice, two days apart. Animals were clinically observed daily for 14 days following treatment initiation. The predominant pathogens present in pretreatment respiratory tract samples were Mannheimia haemolytica and Pasteurella multocida. Mycoplasma bovis and Histophilus somni were also present. All isolates were subjected to in vitro sensitivity testing and found susceptible to florfenicol. In both treatment groups, rectal temperature dropped and clinical index (depression and respiratory signs) significantly improved (P<0.05) after treatment. As a result, 97.7 per cent of the 450 mg/ml florfenicol formulation-treated animals were considered treatment successes on day 5. On day 14, 67.82 per cent of the animals were classified as treatment successes and among them 63.22 per cent were cured. The intramuscular injection of the new 450 mg/ml florfenicol formulation was found equally efficacious as the original 300 mg/ml formulation.

Controlled delivery of a GnRH agonist by a silastic implant (Gonazon) results in long-term contraception in queens.

Many female cats are spayed to prevent problems associated with calling and unwanted pregnancies. This study describes the safety and efficacy of an alternative approach, using an azagly-nafarelin containing implant (Gonazon) inserted subcutaneously in the neck of six treated queens for 3 years. These six queens together with six controls were permanently housed with vasectomized tom cats, and changes in progesterone concentrations were used to document the contraceptive efficacy of Gonazon. All six control queens ovulated regularly throughout the treatment period (3 years), as shown by regular changes in progesterone concentration. Sixteen ovulatory cycles were observed in each control throughout the study. In Gonazon treated queens, during the week following implant placement, two queens displayed a treatment-induced rise in progesterone concentration. Later on, all treated queens continuously displayed low progesterone concentrations until 3 years post-implant insertion, with the exception of a single isolated episode (at approximately 2.5 years of treatment), of follicular luteinization in two queens. In all queens, azagly-nafarelin concentrations peaked in the week following implant insertion remained high for 1 month and later decreased slowly. After 2.5 years of treatment, azagly-nafarelin concentrations were still greater than 150 pg/ml in 3/6 queens. During a 6-month long extension of the study (36-42 months post-treatment), all queens (treated and controls) were run with intact tom cats. None of them conceived. Following autopsy, ovarian weight and diameter of the uterine horns of 3/6 treated queens were shown to be similar to those of the controls. In conclusion, this study demonstrated that Gonazon efficiently prevented ovulation in queens (100%) for 3 years. Return to fertile heat was not observed towards the end of treatment. However, in half of the treated queens, reversibility of the treatment induced effects on the genital tract was demonstrated.

Treatment with a subcutaneous GnRH agonist containing controlled release device reversibly prevents puberty in bitches.

In most species, continuous administration of GnRH agonists desensitizes the pituitary to GnRH, and blocks ovarian function. The aim of this study was to assess the effects of a novel controlled release device containing azagly-nafarelin (Gonazon) to prevent puberty in young Beagle bitches (mean age: 4.88 +/- 0.32 months). Gonazon containing 18.5 mg azagly-nafarelin (n = 10) or a placebo implant (n = 10) was administered subcutaneously. Throughout the 1-year treatment, estrus behaviour was monitored weekly. Plasma progesterone concentrations, as well as body weight and height, were measured monthly. Following implant removal, estrus detection and progesterone measurement were continued until occurrence of puberty in all bitches. Control bitches displayed puberty (estrus, followed by ovulation) at approximately 11.9 +/- 2.7 (range, 8-16) months of age. In contrast, none of the Gonazon treated bitches displayed puberty during the period when Gonazon was present. Following removal of Gonazon, resumption of estrus and ovulation naturally occurred (seven bitches) or was induced (three bitches) approximately 8.5 (1.2-14.3) months later. As a consequence, age of puberty of the Gonazon treated bitches was 25.5 +/- 5 (18-31) months. No clinically detectable side effects were noted in Gonazon treated bitches. Height at withers was unaffected by treatment. Changes in body weight with time were also unaffected by treatment. Implants were well tolerated and generally easy to remove. These data demonstrated that Gonazon safely, efficiently and reversibly prevents reproductive function for 1 year in prepubertal bitches.