This is noticed at six months of pregnancy. This may be due to heat stress, genetic or use of drugs and mostly due to brucellosis a bacterial disease in cow. This transmitted to human in man it reduces undulating fever, swelling of the testis and in woman it causes abortion. Long term antibiotic treatment and sexual rest is the solution. Purchase cows after Brucella testing. Grow your own herd. You can vaccinate young female calves. Brucella vaccine is given at 6 months of age once. The immunity is lifelong. The vaccinated cow show a positive test. There is abortion due to vibriosis at an early stage of pregnancy. This infection spread by natural service so go for AI.
Retention of placenta
After calving, the placenta is not expelled. This is due to the low level of estrogen so infect pregnant once only and consult your veterinary. This may be due to brucellosis. The use of selenium and vitamin E may help if it is due to nutritional deficiency. Usually, the placenta is dropped with an hour of calving. It placenta is manually removed then antibiotic be used too, consult your veterinarian.
Prolapse of Vagina
After conception at the pregnancy of 4 months of the vagina is noticed. It is like a football bladder. This may be genetic, nutritional, it may be allergic, involuntary contraction of the uterus and above all due to the stress. This has to be pushed back immediately because once it is out it swells then it is difficult to push back. Once it is out there may be an injury, immediately consult your veterinarian. Antihistaminic and antispasmodic drugs are helpful. The veterinarian may suture the vagina. But there is every possibility of re-occurrence.
Prolapse of Uterus
In the case of prolapse of the uterus, the whole uterus is inside out. You can see cotyledons and placenta attached to it. This has to be pushed back immediately. Call your veterinarian. The solution to the problem is to select the best bull and use the sexed semen. When the cow is pregnant with female the size is small and small calf will not create a problem you may try Jersey semen because the Jersey female calves are small.