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This article was published in 1974
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Trichomoniasis in Cattle
by P.J. Ahrens, B.V.Sc.,.M.R.C.V.Sc.
Introduction
Seddon (1966) states that although the incidence of trichomoniasis in Australia is not known due to lack of data, it is considered an important and widespread cause of infertility in cattle in this country.
In the northern parts of Australia it is freely acknowledged (Murray, pers. Comm.) that at least a third of cattle herds are infected with the disease.
Since trichomoniasis was first diagnosed in 1948, quite a number of N.S.W. properties, mainly coastal dairy farms, were found to be infected, but in this state, eradication programmes have been carried out in every case.
As a contagious venereal disease causing temporary infertility, endometritis, early abortion and occasionally pyometra, trichomoniasis can be a serious cause of economic loss in infected herds. Just how long the acute stage of an outbreak lasts depends on several factors, but once the disease has become enzootic in a herd, it may be that only a few cows will be adversely affected at any one time.
Elder and Hall (1969) working with the brisbane serotype of Tr. feotus found that infection persisted for only 6 to 12 weeks in cows following initial exposure. Subsequent attempts to re-infect them were unable to establish the organism for longer than 2 weeks. Other workers had previously demonstrated some signs of acquired immunity to the other known serotypes - Tr. feotus var belfast and Tr. feotus var manley. The duration of initial infection was reported variously as 6-14 weeks, 5-20 weeks and in one Queensland study it was found to persist for 19 and 23 weeks (Simmons and Laws, 1957).
Bulls, too, may vary in their resistance to infection. Elder and Hall (1969) for example were able to establish infection in only one of seven bulls for any length of time. Clark et al. (1971) during examinations of 15 bulls found that in two of them the infection disappeared spontaneously after a while. Generally however, bulls are regarded as being fairly permanently infected.
All specimens with any possibility of harbouring Tr. foetus which are received at the Veterinary Research Station, Glenfield from field investigations of infertility and abortion in N.S.W. have been examined routinely for many years (Jakovljevic, 1974, Veterinary Research Station, Glenfield). No doubt the chances of survival of trichomonas in many of these specimens could be questioned, but the fact remains that there is very little evidence of infection in N.S.W. cattle. With the advent of a suitable transport medium, greater reliance will be able to be placed on negative findings. Seddon (1966) stated that it is generally believed the disease is more widespread in N.S.W. than the number of reported outbreaks suggest.
Roberts (1956) claimed that in the American experience dealers' herds and other herds which frequently introduce or replace bulls and cows, are those in which trichomoniasis is most likely to appear.
Case history
The appearance of acute Tr. feotus infertility in a small herd of cattle at Molong in August 1970 thus aroused some interest. It was only the second time that trichomoniasis had been diagnosed in beef cattle in N.S.W. the first time being at Luskintyre in the Maitland P.P. Board district in 1963. In dairy cattle the last reported outbreak had been at Kerang in the Lismore P.P. District in 1964. All attempts at tracing the source of the Molong outbreak were fruitless.
At the original investigation of the severe infertility which had become apparent to the manager over a period of almost a year, it was noted that many of the cows were exhibiting "dirty tails". When vaginal mucus samples were obtained, mucus was copious and in some cases contained discrete flecks of pus which reminded me of the specimens I used to obtain from known trichomoniasis herds when I was at Grafton in 1960. I therefore spent a little time examining the fresh material under the microscope but could see no suspicious protozoa. Glenfield on the other hand quickly reported the presence of live Tr. feotus in one of the samples.
Preputial washings were then obtained from the shorthorn bull which was in the herd but the Laboratory report on these specimens was negative. A few days later the bull was slaughtered at the local abattoirs and the genitalia forwarded to Glenfield. The laboratory report this time was positive.
SCHEDULED DISEASE IN N.S.W.
In areas where no regular A. I. service is operating, the control methods required to be undertaken involve the use of a "sacrifice" bull. Each cow in the herd which calves normally is allowed 3 months sexual rest before being joined to the sacrifice bull. Hopefully the ensuing pregnancy will be successful, because if the cow does not produce a full-term calf she will have to remain in the suspected infected category. It may be better to dispose of such animals for slaughter, or carefully repeat the 3 months rest and mating cycle with the sacrifice bull. Most cows however will complete the pregnancy satisfactorily and after a further period of sexual rest can be regarded as clean.
If the "sacrifice" bull at any stage shows signs of having become infected, it should promptly be disposed of and replaced. Cows with pyometron or chronic anoestrus for some other reason need to be treated or sold for slaughter. An interesting form of trichomonad infection was discovered by Beattie (1955) upon examination of a cow with a prominent 7cm diameter vaginal cyst. The cyst was found to contain catarrhal fluid bearing masses of living and dead Tr. foetus resembling the fluid of pyometritis.
Each infected herd has to be dealt with on its own merits. Not only must the known epizootiology about the disease be borne in mind but due appraisal of the cattle, the fences and the management is necessary in deciding a course of action. The administration of controlled eradication programmes is far from smooth. Official veterinary files contain many examples of programme breakdown, farmer resistance and unforgettable incidents. MyLrea (1961) noted that in some dairy areas, farmers were reticent about infertility problems because of their fear of being quarantined for trichomoniasis.
DIAGNOSIS
In a study of the Bartless pipette method of collecting preputial secretion from Bulls, Clarke et al. (1971) demonstrated that it was 97 per cent efficient. They considered that under the conditions of their trial, the method would have been 100 per cent efficient if any bull is examined on three occasions. The pipette has to be used correctly as recommended by Todorovic and McNutt (1967), the rubber bulb being compressed and relaxed from 15-20 times and the bevelled tip oriented carefully while manipulated back and forth along the preputial and penile mucosa. The sample is kept shielded from direct sunlight and washed into a special culture medium containing antibiotic and antifungal agents.
Four days incubation at 37 deg. is required before final microscopic examination is made. From the cow, specimens are best obtained within 24 hours of abortion, 12 to 19 days after service or 2 to 3 days before oestrum if possible. Discharge from pyometron cases is very satisfactory for diagnostic purposes, as is alimentary contents of aborted foetuses.
Test mating of bulls with several clean heifers has been a favourite method in artificial breeding centres. Following suspicions in 1963 that infected semen from the Aberdeen Stock Breeding Centres had caused out breaks of trichomoniasis in dairy herds, test mating was carried out on the bulls at the centre. Two bulls proved positive to the test. The survival of Tr. foetus in semen frozen to -79 deg, had been demonstrated by Blackshaw and Beattie (1955) but its survival at liquid nitrogen temperatures has not been found as yet. In any case, the additional of 7 per cent glycerol to todays semen packs is considered adequately lethal to any trichomonad organisms.
References
Blackshaw, A.W. & Beattie, H.E.R. (1955) - Aust. vet. J. 31:214.
Beattie, H.E.R. (1955) - Aust. vet, J. 31:146
Clark, B.L. White, M.B. and Banfield, J.C. (1971) Aust.vet.J. 47:181
Elder, J.K. & Hall, W.T.K. (1969) - Qld.J.Aric Sci. 26:672
Jakovljevic, D. (1974) - Veterinary Research Station, Glenfield.
Murray, G.R. (1974) - King Ranch of Aust. Pty. Ltd., Milton Park, Bowral.
Mylrea, P.J. (1961) - Aust. vet. J. 37:302
Roberts, S.J. (1956 - "Veterinary Obstetrics & Genital Diseases", 1st Edit., Ithaca, New York)
Seddon, H.R. revised by Albiston, H.E. (1966) Diseases of Domestic Animals in Australia part 4, Commonwealth
Dept.Health, Canberra.
Simmons, G.C. and Laws, L. (1957) - Aust. vet.J. 33:249
Todorovic, R. & McNutt, S.H. (1967) - Am.J.vet. Res. 28:1581.