Estrumate® is a clear, colourless aqueous solution for injection, containing Cloprostenol Sodium BP (Vet), equivalent to 250 µg/ml cloprostenol. Also contains 0.1% Chlorocresol Ph Eur as a bactericide.
Cloprostenol is a synthetic prostaglandin analogue structurally related to Prostaglandin F2α (PGF2α), for use in cattle and horses. As a potent luteolytic agent it causes functional and morphological regression of the corpus luteum (luteolysis) in cattle and horses followed by return to oestrus and normal ovulation.
There is a refractory period of four to five days after ovulation when cattle and horses are insensitive to the luteolytic effect of prostaglandins. Estrumate® has a good safety margin and does not impair fertility. No deleterious effects have been reported on the progeny conceived at the oestrus following treatment.
A single intramuscular dose is likely to be highly effective in certain clinical conditions in cattle.
(i) Suboestrus (or non detected oestrus — NDO):
This condition occurs in heavy yielding cows, usually at peak lactation, which have normal ovarian cyclicity but in which behavioural manifestation of oestrus is either very mild or absent. Such animals can be treated following diagnosis of a corpus luteum by rectal palpation and then closely observed for oestrus. Those showing heat should be inseminated. Animals not seen in heat should be re-examined 11 days later and may receive a further single injection and be bred at oestrus or at fixed times (see Section (b)).
Where re-examination is carried out 14 days later to fit in with routine fertility visits, animals should be bred on detection of oestrus rather than at fixed times.
(ii) Induction of parturition:
Estrumate® induces parturition in the period around normal term. Induction should take place as close to the predicted calving date as possible and not more than 10 days before. Induction should not be attempted before day 270 of gestation measured from the confirmed day of conception except in pathological conditions (see iv below).
All treated animals must receive adequate supervision.
In common with other methods of shortening the gestation period a higher than usual incidence of retention of the foetal membranes is to be expected.
(iii) Termination of normal pregnancy:
Normal pregnancy can be terminated in cattle from one week after conception until the 150th day of gestation. Before 100 days of gestation, abortion can be induced rapidly and efficiently but between 100 and 150 days of gestation results are less reliable, probably because a proportion of cattle may become progressively less dependent upon the corpus luteum for the maintenance of pregnancy. Abortion should not be attempted after day 150 of gestation. Treated animals should be kept under observation and examined in order to ensure that expulsion of the foetus and the placental membranes is complete. Termination of more advanced pregnancy requires more complex treatment regimes and greater post-treatment care.
(iv) Termination of abnormal pregnancy
Death of the conceptus may be followed by its dehydration and degeneration. Induction of luteolysis at any stage of pregnancy will result in the expulsion of the mummified foetus from the uterus into the vagina from which manual removal may be necessary. Normal cyclical activity should then follow.
Hydrops of the foetal membrane
Pathological accumulation of placental fluids – hydramnios or hydrallantois — can cause severe physiological complications and death. Surgical drainage is not usually successful in alleviating the condition.
A single dose may be used to induce parturition in such cases; success has been achieved as early as the sixth month of pregnancy.
(v) Chronic endometritis (Pyometra):
This condition may be successfully treated with a single dose. In longstanding cases treatment may be repeated after 10 – 14 days.
(vi) Ovarian luteal cysts:
Where cystic ovaries associated with persistent luteal tissue and absence of oestrus are diagnosed, Estrumate has proved effective in correcting the condition and bringing about a return to cyclicity.
(b) Controlled breeding in cattle:
The luteolytic activity of Estrumate® can be harnessed to control the breeding pattern of cattle.
A variety of treatment regimes exists from which to choose the most appropriate for the characteristics and objectives of each particular herd. Individuals or groups of animals can be controlled, as required. Estrumate can be used to complement the herdsman's oestrus detection input, or animals may be bred `on schedule' during critical times of the breeding season, without reference to oestrus detection, as preferred.
Controlled breeding programmes in cattle
Examples of programmes which have been used are:
Cattle which respond to a single prostaglandin injection will normally do so within 6 days of treatment. The response time after two injections is more rapid. Animals may be inseminated on detection of oestrus in any of the Estrumate® programmes. However, fixed time insemination should only be used following the second of a two injection programme (i.e. examples 3 and 4). In the latter case, insemination should be performed either once at 72—84 hours or twice at 72 and 96 hours after the second injection, as preferred.
Double 'fixed-time' insemination may give superior results to a single insemination. However, economic factors in the particular herd may outweigh such a benefit.
For successful treatment, animals should be cycling normally. Rectal examination before treatment should avoid the disappointment of treating non-cycling (anoestrous) or pregnant animals.
Attention should be directed to the diet and condition of the treated animals. Sudden changes in feeding levels, in feed constituents and in housing, etc. should be avoided around the time of the breeding programme, as should any other factors, such as regrouping, which could reasonably be expected to lead to stress.
If artificial insemination is to be used, the quality of semen and insemination technique should be assured beforehand.
Control of the oestrous cycle is of value in the:
i) Dairy herd
ii) Beef herd
Administer by intramuscular injection. Due to the possibility of post-injection bacterial infections observe normal aseptic precautions. Care should be taken to avoid injection through wet or dirty areas of skin.
Following withdrawal of the first dose, use the product within 56 days. Discard unused material.
On rare occasions severe life-threatening local bacterial infections may occur associated with clostridial proliferation. It is important to keep treated animals under observation and, if local infection occurs, aggressive antiobiotic therapy is a matter of urgency.
Overdose in cattle: At x5 to x10 overdose the most frequent side effect is increased rectal temperature. This is usually transient, however, and not detrimental to the animal. Limited salivation may also be observed in some animals.
Prostaglandins of the F2α type can be absorbed through the skin and may cause bronchospasm or miscarriage.
Care should be taken when handling the product to AVOID SELF-INJECTION OR SKIN CONTACT
Women of child-bearing age, asthmatics and persons with bronchial or other respiratory problems should avoid contact with, or wear disposable plastic gloves when administering, the product.
The possible incidence of bronchospasm with Estrumate® is unknown. Should shortness of breath result from accidental inhalation or injection, seek urgent medical advice and show the doctor this warning.
Accidental spillage on the skin should be washed off immediately with soap and water.
Cattle should not be slaughtered for human consumption within 24 hours after administering the product.
It is unnecessary to discard milk from treated cattle.
Store at room temperature, protected from light. Keep out of the reach of children
Multidose vials of 10 ml or 20 ml.
Attention: In many countries Estrumate® is also licensed for use in horses and/or pigs. For details please consult your Merck Animal Health representative and the product data insert