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This article was published in 1949
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INSTITUTE OF INSPECTORS OF STOCK OF N.S.W. YEAR BOOK.
TRICHOMONIASIS IN CATTLE
J. T. HAYSTON. B.V.Sc. P.P. Boards' Veterinary Research Officer, Glenfield.
Bovine Trichomoniasis is a non-febrile venereal disease of cattle characterised by difficulties associated with breeding and early abortion. The disease is caused by the protozoan organism, Trichomonas foetus.
In New South Wales the disease has been diagnosed, by the recognition of the causal organism, on two properties in the Kiama district and on one in the Grafton district. It is practically certain that two properties in the Singleton district also are affected.
A significant feature of the history of affected herds is the occurence of breeding troubles following the introductions of new animals into the herd. Most infections due to Trichomoniasis usually culminate in an abortion. The abortions may occur any time during the period of gestation, but usually take place in from eight to 16 weeks after coitus. A few days after an abortion the animal usually comes into oestrus and this in often the first indication of infection. On infected properties there is a history of cows returning to the bull, either continually or rollowing an early abortion. In most instances the owners have placed the cows to service by different bulls, hoping that a conception may eventuate, but this merely has spread the infection more widely within the herd.
Infected cows sometimes show a vaginal discharge of a serous, tenacious nature. If catheterisation of the uterus is carried out shortly after abortion, a very characteristic discharge may be seen; this discharge being a thin, odourless fluid containing numerous white flecks, which are revealed on microscopic examination to be mixtures of polymorphonuclear cells and Trichomonads. To establish a diagnosis, microscopic examination should be made of vaginal or uterine exudates from suspected cows. The exudates may be examined from cows which have aborted recently; from pregnant animals or from nonpregnant cows at the oestral period.
DIAGNOSIS
The outstanding feature of the disease is an early abortion. Usually the abortion is complete, and seldom are any the the foetal membranes retained. Cattle affected with Trichomoniasis frequently show an irregular oestrus cycle. The inability to demonstrate the presence of the organism in a herd where the history is suggestive of the disease, is not necessarily a criterion that the herd is not infected. It may mean merely that the examination was not made at the right time, and the examination should be repeated later and on a number of cows. It is usually easy to demonstrate the organism in cows which are examined within two days following an abortion.
For the purpose of diagnosis, unstained fresh preparations of uterine or vaginal exudates are most suitable. These preparations should be examined an soon as is convenient after collection. The material should be examined by placing it between a slide and coverglass under the low or high power of the microscope; the use of an oil-immersion lens not being necessary. In material from suitable cases the trichomonads will be seen swimming actively; in other cases a long search may be necessary before the protozoa are demonstrated. Once seen, these organisms are recognised easily us subsequent occasions.
Trichomonas foetus has three anterior flagella, each of which is about as long as the body of the organism, and a posterior flagellum constituting the marginal filament of the undulating membrane as a free flagellum; all flagella being approximately the same length. In general, T. foetus is somewhat larger than a polymorphonuclear and smaller than an epithelial cell. The organisms are usually actively motile and they move with an undulating motion. In a fluid uterine exudate the protozoa usually move rapidly and assume forms resembling pears or bream-fish as they become streamlined in the direction of the motion. Vaginal mucus is usually somewhat tenacious, and this considerably restricts the movements of the organisms; the movements may be confined to show waving of the undulating membrane, and the organisms themselves may be round or oval in shape. Stained preparations offer no advantage for diagnosis. In fact, the organisms, being no longer motile, are much more difficult to distinguish than in the case with fresh, wet-smear preparations.
Overseas workers have reported favourably upon complement fixation and agglutination tests being used in the diagnosis of Trichomoniasis. The antigen well in the tests is prepared from cultures of the organisms in special media. There seems to be considerable doubt concerning the accuracy of these tests, and at the present time it is safe to say that the only certain basis for diagnosis is the microscopic demonstration of the causal protozoa.
TREATMENT
Cows that abort early in the period of gestation usually recover spontaneously, provided the abortion is complete and the animals are given a period of sexual rest for about three months. If the abortion is incomplete and there is a persistent discharge, the animals should be handled as cases of uterine infection due to other causes. Cows that fail to conceive after repeated services, as a result of trichomonad infection, should not be mated until after three normal oestral cycles. Treatment by the use of uterine irrigation or uterine injection of iodised paraffin is desirable.
On the fourth oestral period (providing the previous cycles have been normal and the cows are showing no abnormal discharges) the animals may be bred, preferably by artificial insemination; using semen from a clean bull.
Infected bulls have been considered to be incurable. It appears that the trichomonads may penetrate into and remain in the seminal vesicles and urethra. There usually is considerably difficulty in demonstrating the presence of the organisms in bulls, and because of the difficulty in treating them successfully, and more particularly, in determining whether or not they are infected, the destruction of the bulls has been advocated as a means of eliminating sources of infection.
American work has shown that the use of intravenous injections of sodium iodide will effect a number of cures in bulls. These animals are given five grams of sodium iodide per 100 pounds of body weight, dissolved in 500 ml. of sterile distilled water. Five similar treatments are given, at intervals of two days.