Vet on call: For smooth pig farming, pay heed to vaccination

The caller sounded distressed. She spoke quite fast, until I told her to slow down to enable me to take notes. I do not like interrupting a caller but then it is unprofessional to listen to half the story and take the person back to the start to record details of the case.

I captured the pertinent issues of the narration for 10 uninterrupted minutes. “Doctor, you have to help me save my pig herd,” Asunta concluded.

She said she had invested a lot in the pigs over the past two years but the occurrence of disease on the farm since July 2019 to last month had shocked her confidence in the venture. She wondered whether she could be having an attack of the dreaded African swine fever (ASF).

I told her she definitely had a bigger problem that could gently wipe out her pig herd but it was not ASF.

Her 19 pigs had produced 216 piglets between July 2019 and January 2020 but only 78 piglets had survived. This in medical terms is a huge breeding failure. Commercially, it is a disaster.

The occurrence would seriously disrupt her breeding and expansion programme and revenue projections. This kind of occurrence is frequent on livestock farms if the investor misses on key disease control and prevention activities.

It is worst in pigs and poultry where the profitability of the investment depends on production of large numbers of animals.

So how did Asunta fall this low? Let us first consider her report in deeper detail. She said her pigs had done very well up to June last year.

In July, she expected two sows to farrow but they went past their due date by 12 days. She was concerned when the sows started shrinking and yet they were still pregnant.

This was mistake number one. A farmer should get concerned if the sow exceeds the due date by more than five days. Most sows will deliver on the expected day plus or minus two days.

CAUSE DEATH

The sows were induced to farrow and they gave birth to 12 and 15 piglets that were shrunken and coloured black.

Medically, these are called mummified foetuses and it was the reason the sows were shrinking.

During pregnancy, the uterus extends greatly with the increasing size of the foetuses and corresponding increase in the uterine fluids. The fluids keep the foetuses clean and protected from external shock.

Certain infections may cause the death of the foetuses without rotting. Once the pregnancy goes beyond term, the body absorbs back the foetal fluids, leaving a gelatinous protein and foetal waste material in the uterus.

This turns brown, black and sticky as it gets more dehydrated. Such dead foetuses are called mummies and they can remain in the uterus for long periods, making the sow infertile. The reduction in uterine fluids is seen outwardly as shrinking of the size of the sow.

The farmer committed a second error by not following up on the occurrence of 27 mummies in her herd. The sows appeared to have recovered and they were even served again.

The shocker came in October. Seven sows gave birth to a mixture of mummies, still births and freshly dead piglets.

Other piglets looked normal but most died within seven days of birth. Others were weak and died soon after birth. One sow gave birth to 21 piglets with 17 alive. Out of these, only six survived despite lots of efforts to nurture them.

At that point, Asunta sought help. She neither got a diagnosis nor a solution to the problem but she knew something was terribly amiss.

The October nightmare was repeated through January, when she was referred to me by her friend. I had assisted the friend early last year to sort out a big problem of diarrhoea in his piglets.

From the history the farmer gave, it was evident she had a severe attack of the Porcine parvovirus. It is a common problem globally but fortunately, it can be prevented using vaccine.

The virus infects piglets in the uterus but does not usually kill the mother. In some cases, it will kill all the piglets but the most common occurrence is a mixture of outcomes as seen with Asunta’s herd.

BREEDING FAILURE

When foetuses are infected before 35 days of pregnancy, they may be resorbed and the pigs get back to heat. Porcine parvovirus infection, therefore, kills a pig herd by causing severe breeding failure.

The virus does not infect humans and is different from the Human parvovirus and the deadly Canine parvovirus of dogs.

An outbreak of Porcine parvovirus infection is diagnosed based on the clinical signs or through laboratory investigation. Laboratory investigation is expensive and, therefore, the farmer opted I treat the problem based on the clinical signs.

I advised her to put her pigs on a diligent vaccination programme for the disease, which was to start immediately. She introduced me on phone to her paravet animal health service provider, Wahome. I detailed to him the vaccination programme and how to administer the vaccine.

Asunta immediately bought the vaccine and Wahome vaccinated all the breeders. I, however, cautioned her that some of the pregnant sows may still give birth to defective piglets since they could already have been infected at the time of vaccination.

She would only see the full outcome of vaccination when all the sows and the boar were protected before breeding.

Farmers should always vaccinate their pigs routinely against the following common diseases: Porcine parvovirus, Gut oedema, Swine erysipelas and Foot and mouth disease.

Fortunately, all these vaccines are recommended for routine use in the breeding stock. The commercial stock comprising the porkers and baconers are not vaccinated because the piglets have immunity from their mothers.