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Trichomonas fetus —Induced abortion
THERIOGENOLOGY
TRICHOMONAS
FETUS-INDUCED
ABORTION
SUMMARY
History and--Clinical Signs: Herds infected with Trichomonas fetus have histories ofmlty, occasional abortions, and pyometra. There are no specific gross lesions in the fetus. The Gross Lesions: fetuses are usually aborted in the first half of gestation and may or may not be accompanied by the placenta. There are no specific microscopic lesions. Microscopic Lesions: It is ordinarily not necessary to culture Cultural Procedures: -fetusin order to demonstrate its presence in placental fluids %d/orbomasal contents. Serolo ic Procedures: There are no suitable serologic procedures for di%%&ioT' rlchomoniasis. Wet mounts of abomasal contents and/or placental Syefial Procedures: f ulds are examined microscopically for -T. fetus. Demonstrate the presence of T. Preferred Diagnostic Procedures: _I_ fetus by microscopic examination of wet mounts of placental fluids and/or abomasal contents.
LABORATORY
DIAGNOSIS
OF TRICHOMONAS
FETUS-INDUCED
ABORTION
Trichomoniasis is a contagious, venereal disease of cattle It is caused by characterized by sterility, abortion and pyometra. the flagellated protozoan parasite Trichomonas fetus. Abortion and pyometra are often the first signs of trichaasis that are noticed in a herd, but they occur in relatively few animals. Sterility is the most prevalent and damaging symptom and occurs in a high percentage During the infertile period the of animals in a recently infected herd. length of the estrous cycles may vary from normal. Heifers are usually considered to be the most susceptible. However, immunity does not increase with age but is created through exposure. Infection is confined to the genital tract and, with one exception (noted below) transmission is through sexual contact. Spread of the disease in artificial insemination bull studs is presumed to have occurred through contact of the penis with the rump or escutcheon of the teaser animal which had been contaminated through similar contact by an infected animal, With this exception, control measures may be based upon the assumption that transmission is by coitus. The appearance of the previously mentioned symptoms, usually following the introduction of an animal into the herd, gives cause to suspect either trichomoniasis or vibriosis. In the case of trichomoniasis the diagnosis rests upon finding and observing the organism in at least one animal in the herd. NO other tests are satisfactory for the detection of trichomoniasis. In the aborted fetus many organisms can be found in the placental fluids and in the stomach contents. Occasionally they occur in the lungs and heart blood of the fetus. They are also present in the uterus for several days after abortion. They can be seen by placing these fluids on a glass slide and observing them microscopically.
150
MARCH
1976
VOL.
5 NO. 3
THERIOGENOLOGY
Most abortions due to T. fetus occur in the first half Of gestation although a few have been reporms late as the 7th month. The fetal In the latter membranes may be expelled with the fetus or retained. case a chronic catarrhal or purulent endometritis usually results. The affected cow may become sterile because of the resultant destruction of the uterine mucosa. For examination cover about l/2 of a glass slide with placental fluid By not using a cover slip a relatively large VOTUme or abomasal content. Trichomonads tend to migrate of fluid may be examined in a brief time. downward in the fluid, so using 100 x magnification, the microscope is focused just above the surface of the glass. Any moving objects are examined closely by focusing up and down until they are seen clearly. The organism can be identified at 100x on the basis of its size, shape and characteristic aimless, jerky motion caused by the movement However, distinguishing of the flagella and undulating membrane. characteristics such as flagella and undulating membrane are clearly visible only at higher magnification (500x). Using the greater magnification the three anterior flagella as well as the constant spiral-like motion of the undulating membrane can be seen. Dead trichomonads quickly lose their shape and become indistinguishable from any debris present. Therefore, they are almost impossible to identify by direct examination. If an abortion due to T. fetus is diagnosed the entire herd of origin must be considered as possii;iyinfected. While there may be some question as to which cows are infected, it is almost certain that the bull is. Because abortion is rare in herds infected with T. fetus, it is often necessary to examine cows, and more often bulls, when herd history indicates the possible presence of the infection. Several successful procedures for taking specimens from cows and bulls have been described. Because of the large number of organisms usually present in placental fluids and abomasai contents of fetuses aborted due to trichomoniasis, it is seldom necessary to culture the specimens in order to demonstrate the presence of trichomonads. However, in examining uterine or preputial fluids culturing greatly increases the efficacy of the examination. A suitable medium for culturing trichomonads is given in Appendix A. NO gross or microscopic fetal lesions are specific for T. fetus. The diagnosis is based almost entirely on the demonstration 5f -presence of -T. fetus in the aborted fetus.
MARCH 1976
VOL. 5 NO. 3
151
THERIOGENOLOGY
APPENDIX CULTURE MEDIUM
Difco beef extract Distilled water Dextrose Bacto. peptone Agar Sodium chloride Penicillin Dihydrostreptomycin Sheep serum
A
FOR T. -~ FETUS
3 gm. 1 liter 10 gm. 10 gm. 0.7 gm. 1 gm. 5000 units/ml 1 mg/ml 30 ml. (inactivated
30 min. at 56'C)
All ingredients except the sheep serum and antibiotics are added to a 3-liter flask and dissolved by boiling. After cooling, the pH is adjusted to 7.4 with dilute sodium hydroxide. The mixture is autoclaved for 30 minutes at 15 lbs. pressure, aseptically distributed in 10 ml amounts into sterile 15 ml screw-top vials, and incubated to test for contamination. Just before use. the sheeo serum and antibiotics are added. The inoculum is carefully pipetteb onto the top of the medium in the vial to minimize mixing. This is a very important step because the trichomonads migrate to the bottom of the~vial while the yeast and molds tend to remain near the top. Bacterial growth tends to The inoculated vials are concentrate about a half inch below the surface. incubated 3 to 5 days at 37 C after which a sample is removed from the bottom of the tube with a glass pipette or hypodermic needle and examined microscopically.
152
MARCH
1976
VOL. 5 NO. 3
TRICHOMONAS
FETUS-INDUCED
ABORTION
SUMMARY
History and--Clinical Signs: Herds infected with Trichomonas fetus have histories ofmlty, occasional abortions, and pyometra. There are no specific gross lesions in the fetus. The Gross Lesions: fetuses are usually aborted in the first half of gestation and may or may not be accompanied by the placenta. There are no specific microscopic lesions. Microscopic Lesions: It is ordinarily not necessary to culture Cultural Procedures: -fetusin order to demonstrate its presence in placental fluids %d/orbomasal contents. Serolo ic Procedures: There are no suitable serologic procedures for di%%&ioT' rlchomoniasis. Wet mounts of abomasal contents and/or placental Syefial Procedures: f ulds are examined microscopically for -T. fetus. Demonstrate the presence of T. Preferred Diagnostic Procedures: _I_ fetus by microscopic examination of wet mounts of placental fluids and/or abomasal contents.
LABORATORY
DIAGNOSIS
OF TRICHOMONAS
FETUS-INDUCED
ABORTION
Trichomoniasis is a contagious, venereal disease of cattle It is caused by characterized by sterility, abortion and pyometra. the flagellated protozoan parasite Trichomonas fetus. Abortion and pyometra are often the first signs of trichaasis that are noticed in a herd, but they occur in relatively few animals. Sterility is the most prevalent and damaging symptom and occurs in a high percentage During the infertile period the of animals in a recently infected herd. length of the estrous cycles may vary from normal. Heifers are usually considered to be the most susceptible. However, immunity does not increase with age but is created through exposure. Infection is confined to the genital tract and, with one exception (noted below) transmission is through sexual contact. Spread of the disease in artificial insemination bull studs is presumed to have occurred through contact of the penis with the rump or escutcheon of the teaser animal which had been contaminated through similar contact by an infected animal, With this exception, control measures may be based upon the assumption that transmission is by coitus. The appearance of the previously mentioned symptoms, usually following the introduction of an animal into the herd, gives cause to suspect either trichomoniasis or vibriosis. In the case of trichomoniasis the diagnosis rests upon finding and observing the organism in at least one animal in the herd. NO other tests are satisfactory for the detection of trichomoniasis. In the aborted fetus many organisms can be found in the placental fluids and in the stomach contents. Occasionally they occur in the lungs and heart blood of the fetus. They are also present in the uterus for several days after abortion. They can be seen by placing these fluids on a glass slide and observing them microscopically.
150
MARCH
1976
VOL.
5 NO. 3
THERIOGENOLOGY
Most abortions due to T. fetus occur in the first half Of gestation although a few have been reporms late as the 7th month. The fetal In the latter membranes may be expelled with the fetus or retained. case a chronic catarrhal or purulent endometritis usually results. The affected cow may become sterile because of the resultant destruction of the uterine mucosa. For examination cover about l/2 of a glass slide with placental fluid By not using a cover slip a relatively large VOTUme or abomasal content. Trichomonads tend to migrate of fluid may be examined in a brief time. downward in the fluid, so using 100 x magnification, the microscope is focused just above the surface of the glass. Any moving objects are examined closely by focusing up and down until they are seen clearly. The organism can be identified at 100x on the basis of its size, shape and characteristic aimless, jerky motion caused by the movement However, distinguishing of the flagella and undulating membrane. characteristics such as flagella and undulating membrane are clearly visible only at higher magnification (500x). Using the greater magnification the three anterior flagella as well as the constant spiral-like motion of the undulating membrane can be seen. Dead trichomonads quickly lose their shape and become indistinguishable from any debris present. Therefore, they are almost impossible to identify by direct examination. If an abortion due to T. fetus is diagnosed the entire herd of origin must be considered as possii;iyinfected. While there may be some question as to which cows are infected, it is almost certain that the bull is. Because abortion is rare in herds infected with T. fetus, it is often necessary to examine cows, and more often bulls, when herd history indicates the possible presence of the infection. Several successful procedures for taking specimens from cows and bulls have been described. Because of the large number of organisms usually present in placental fluids and abomasai contents of fetuses aborted due to trichomoniasis, it is seldom necessary to culture the specimens in order to demonstrate the presence of trichomonads. However, in examining uterine or preputial fluids culturing greatly increases the efficacy of the examination. A suitable medium for culturing trichomonads is given in Appendix A. NO gross or microscopic fetal lesions are specific for T. fetus. The diagnosis is based almost entirely on the demonstration 5f -presence of -T. fetus in the aborted fetus.
MARCH 1976
VOL. 5 NO. 3
151
THERIOGENOLOGY
APPENDIX CULTURE MEDIUM
Difco beef extract Distilled water Dextrose Bacto. peptone Agar Sodium chloride Penicillin Dihydrostreptomycin Sheep serum
A
FOR T. -~ FETUS
3 gm. 1 liter 10 gm. 10 gm. 0.7 gm. 1 gm. 5000 units/ml 1 mg/ml 30 ml. (inactivated
30 min. at 56'C)
All ingredients except the sheep serum and antibiotics are added to a 3-liter flask and dissolved by boiling. After cooling, the pH is adjusted to 7.4 with dilute sodium hydroxide. The mixture is autoclaved for 30 minutes at 15 lbs. pressure, aseptically distributed in 10 ml amounts into sterile 15 ml screw-top vials, and incubated to test for contamination. Just before use. the sheeo serum and antibiotics are added. The inoculum is carefully pipetteb onto the top of the medium in the vial to minimize mixing. This is a very important step because the trichomonads migrate to the bottom of the~vial while the yeast and molds tend to remain near the top. Bacterial growth tends to The inoculated vials are concentrate about a half inch below the surface. incubated 3 to 5 days at 37 C after which a sample is removed from the bottom of the tube with a glass pipette or hypodermic needle and examined microscopically.
152
MARCH
1976
VOL. 5 NO. 3