Lutalyse is indicated for its luteolytic and/or oxytocic effect in cattle, horses and pigs.
The indications for use are:
Cattle
1To more effectively control the time of oestrus in cycling cows.
2To treat cows which have a functional corpus luteum, but do not express behavioural oestrus (sub-oestrus or silent heat).
3To induce abortion.
4To induce parturition.
5For treatment of chronic metritis and pyometra.
6For controlled breeding in normally-cycling dairy cows:
- oestrus synchronisation
- ovulation synchronisation in combination with GnRH or GnRH analogues as part of fixed time artificial insemination protocols.
Mares
7To more effectively control the time of oestrus in cycling mares.
8To treat mares which have a functional corpus luteum but do not express behavioural oestrus.
9To induce abortion.
Pigs
10Induction of parturition.
11To reduce the weaning to oestrus interval (WOI) and the weaning to fertile service interval (WFSI) in sows in herds with reproductive problems.
Notes
1. Oestrus control in cycling cattle and horses
Individual cows or heifers treated during dioestrus will normally return to oestrus and ovulate within two to four days after treatment.
Mares treated during dioestrus will normally return to oestrus within two to four days and ovulate 8 to 10 days after treatment.
This may be employed to advantage as an effective aid towards managing oestrus and breeding in individual animals. (Note: Administration of Lutalyse to cattle and horses within four days after oestrus is unlikely to result in luteolysis of the corpus luteum. Administration within 48 hours before onset of the next oestrus may not influence the timing of the oestrus after treatment.)
2. Treatment of sub-oestrus (no visible oestrus) in cattle and horses
Individual cattle may have normal cyclical ovarian activity, without detectable behavioural oestrus; this occurs most frequently in the winter months, at peak lactation in high producing dairy cows and in suckle beef cows. If a corpus luteum is present and ovulation has not occurred in the previous four days, administration of Lutalyse will result in corpus luteum regression followed by return to oestrus and ovulation.
Breeding of cattle treated with Lutalyse for the above indication may be by natural service, artificial insemination at the usual time in relation to observed oestrus, or by fixed time insemination (78 hours or 72 and 90 hours post-treatment).
In extended dioestrus in mares there is failure to exhibit regular oestrus cycles as distinct from true anoestrus. Many mares described as anoestrual during the breeding season have serum progesterone levels consistent with the presence of a functional corpus luteum.
A proportion of `barren', maiden and lactating mares do not exhibit regular oestrus cycles and may be in extended dioestrus. Following abortion, early foetal death and resorption, or as a result of `pseudo-pregnancy' there may be serum progesterone levels consistent with a functional corpus luteum.
Treatment of such mares with Lutalyse usually results in regression of the corpus luteum followed by oestrus and/or ovulation.
3. Induction of abortion
Lutalyse may be used to terminate pregnancy in cattle and mares through its luteolytic effect during those stages of pregnancy in which the corpus luteum is sensitive to its action and in which maintenance of pregnancy is dependent upon the corpus luteum as the sole source of progesterone.
Stage of gestation in cattle is an important factor influencing response. The percentage of animals responding to a single intramuscular injection decreases as the gestation period increases. Approximate percentages responding are 90% within the first 100 days of gestation, 60% within 101–150 days of gestation and 40% in animals beyond 150 days of gestation. In the early stages of gestation, abortion will usually occur within one week, but as gestation length increases, the period to abortion following injection may also increase. In mares up to day 35 of pregnancy luteal regression with Lutalyse will induce abortion; response to treatment between days 40 and 90 of gestation is less predictable, possibly due to PMSG secretion from the endometrial cups rendering the corpus luteum refractory to the luteolytic effect of Lutalyse. Between days 90 and 120 of pregnancy luteal regression may lead to abortion.
4. Induction of parturition in cattle and pigs
Cattle: Lutalyse has been used to induce parturition on or after day 270 of gestation. The interval from administration to parturition is one to eight days (average three days). Induction of parturition in cattle is indicated where there is a risk of oversize calves or where early parturition is desired. In addition, induction is indicated where pregnancies are complicated by miscellaneous conditions such as mummified or macerated foetuses, hydrops amnii, hydroallantois, etc. Lutalyse is indicated for expulsion of a dead foetus.
Pigs: Lutalyse may be used to induce parturition in pigs within 3 days of the normal predicted farrowing date. Response to treatment by individual animals varies within a range of 24–36 hours from administration to parturition. This can be advantageously employed to control the time of farrowing in sows and gilts in late gestation. Treatment earlier than 3 days prior to predicted farrowing date may produce weak piglets resulting in reduced survival. It is recommended that treatment be given in the early morning following feeding. A lack of response has been noted in a small proportion of pigs, the specific reason for which has not yet been determined.
5. Treatment of metritis or pyometra in cattle
In the cow chronic metritis frequently occurs as a sequel to an acute or sub-acute endometritis in the first two or three weeks post-partum; typically, there is an intermittent purulent or mucopurulent discharge. Pyometra is characterised by the retention of purulent fluid within the uterus.
Luteal regression through the administration of Lutalyse is followed by oestrus, during which the uterine environment is relatively unfavourable to the bacteria involved in the infection. Treatment may have to be repeated after 10–12 days where the condition is longstanding.
6. Controlled breeding in cattle
Lutalyse is indicated for its luteolytic effect in cattle. This luteolytic effect can be utilised to control the timing of oestrus in cycling cattle that have a corpus luteum. For normally-cycling cows, at least 35 days after calving, the identified activity of Lutalyse permits a wide range of oestrus control programmes.
Programme I
12Inject 5 ml Lutalyse intramuscularly;
13Repeat the injection in 11 (10 to 12) days; then,
14Inseminate 78 (75 to 80) hours after the second Lutalyse injection. No oestrus detection or observation is required if animals were cycling normally when injected.
This programme is recommended for most herds with successful A.I experience where females are known to be cycling.
Programme II
15Inject 5 ml Lutalyse intramuscularly;
16Repeat the injection in 11 (10 to 12) days; then,
17Inseminate 72 (70 to 74) hours and 90 (88 to 96) hours after the second Lutalyse injection. No oestrus detection or observation is required if animals were cycling normally when injected.
Double insemination has demonstrated increased pregnancy rates in some herds.
Programme IIIa
18Inject 5 ml Lutalyse intramuscularly;
19Repeat the injection in 11 (10 to 12) days; then,
20Inseminate upon detected oestrus.
Programme IVa
21Inject 5 ml Lutalyse intramuscularly;
22Inseminate upon detected oestrus.
a If it is unknown whether most animals to be treated are cycling, Programmes III and IV calling for oestrus detection should be followed rather than Programmes I and II calling for timed insemination. A 'clean-up bull' may be used following any Lutalyse programme, or the service may be repeated at the next oestrus, one cycle later, in animals that did not conceive at first service.
Practical application of these programmes will vary depending upon many factors, and in many cases these programmes may be altered to meet the requirements of the specific operation. For example, some veterinary surgeons may wish to design their own programmes for specific situations and schedules. The activity of Lutalyse may be easily adapted for such individualised approach. These changes should be carefully evaluated to ensure that they do not detrimentally affect the success of the breeding programme.
Programme V
Lutalyse may be used as part of a fixed time artificial insemination protocol to synchronise ovulation for normally-cycling dairy cows at any stage of lactation. The following protocols have been commonly reported in the literature:
•Day 0 – Inject GnRH or analogue
•Day 7 – Inject 5 ml Lutalyse intramuscularly
•Day 9 – Inject GnRH or analogue
•Artificial insemination 16–20 hours later or at observed oestrus if sooner.
Alternatively:
•Day 0 – Inject GnRH or analogue
•Day 7 – Inject 5 ml Lutalyse intramuscularly
•Artificial insemination and inject GnRH or analogue 60–72 hours later or at observed oestrus if sooner.
To maximise conception rates of cows to be treated, the ovarian status should be determined and regular cyclic ovarian activity confirmed. Optimal results will be achieved in healthy normally-cycling cows.
7. To reduce the weaning to oestrus interval (WOI) and the weaning to fertile service interval (WFSI) in sows in herds with reproductive problems
PGF2α has a stimulating effect on uterine contractions, leading to better post-partum evacuation of the uterus. Field clinical trials in herds with reproductive problems confirmed that treatment with Lutalyse resulted in a more rapid return to oestrus and fertile service after farrowing.