Background and history

This is a herpes virus found in the tissues throughout the body including the nose of newborn piglets where it causes inflammation (rhinitis). PCMV is present throughout the world and exists in most if not all pig populations but most infections are sub-clinical and clinical disease is rare. Serology carried out in the UK, for example, indicates that over 90% of herds have been exposed to infection.

The virus is excreted in discharges from the nose and eyes, urine and farrowing fluids. It is also transmitted via the boar through semen and crosses the placenta to infect piglets before birth.

The rhinitis produced by this virus is uncommon and mild and has no relationship to atrophic rhinitis caused by the toxin-producing bacteria Pasteurella multocida. In most herds therefore the infection is insignificant and apart from sometimes causing a mild sneeze has no major effect on the health of the pig.

Similar diseases

The disease might be confused with atrophic rhinitis or bordetella infection of the nose, however the effects are very short lived and there is no progressive atrophy or distortion of the nose.

PCMV rhinitis only occurs in newborn piglets and there is a tendency to assume that sneezing in piglets must be associated with atrophic rhinitis. Rhinitis means inflammation of the delicate tissues in the nose and is caused by dust, gases, bacteria or viruses, in fact any irritant. If toxin producing pasteurella are present the inflammation persists with damage and progressive destruction of the tissues (atrophy). This is a serious disease. It can be differentiated from PCMV by swabbing the noses of sneezing piglets and testing for the presence or absence of the pasteurella. It is important to carry this out because if the tests are negative you have no worries (or expensive treatments).

Clinical signs

Clinical signs are only seen if PCMV infects a sow for the first time when she is late in pregnancy. Signs include foetal deaths, mummified foetuses, stillbirths and weak piglets. The sow may run a slight fever and be off her food. Rhinitis in newborn piglets can be severe enough to cause haemorrhage from the nose. In herds in which PCMV is endemic there are no symptoms other than mild sneezing in sucking and weaned piglets.

Piglets and weaners

• Rhinitis in newborn piglets can be severe enough to cause haemorrhage from the nose if sows are naive which would be very rare.
• In herds in which PCMV is endemic there are no symptoms other than mild sneezing in sucking and weaned piglets.
• Possibly fever.

Growers

• N/A

Sows

• Clinical signs are rare and only seen if PCMV infects a sow for the first time when she is late in pregnancy.
• Foetal deaths.
• Mummified foetuses.
• Stillbirths.
• Weak piglets.
• A slight fever.
• Inappetence.
• Nasal haemorrhage.

Diagnosis

This can be confirmed by serological tests, fluorescent antibody tests and demonstration of inclusion bodies in tissue sections.

The disease might be confused with atrophic rhinitis or bordetella infection of the nose, however the effects are very short lived and there is no progressive atrophy or distortion of the nose.

PCMV rhinitis only occurs in newborn piglets and there is a tendency to assume that sneezing in piglets must be associated with atrophic rhinitis. Rhinitis means inflammation of the delicate tissues in the nose and is caused by dust, gases, bacteria or viruses, in fact any irritant. If toxin producing pasteurella are present the inflammation persists with damage and progressive destruction of the tissues (atrophy). This is a serious disease. It can be differentiated from PCMV by swabbing the noses of sneezing piglets and testing for the presence or absence of the pasteurella. It is important to carry this out because if the tests are negative you have no worries (or expensive treatments).

Causes

• The virus is shed in discharges from the nose and eyes, urine and farrowing fluids.
• It is also transmitted via the boar through semen and crosses the placenta to infect piglets before birth.
• Poor environmental conditions.
• Fluctuating temperatures may predispose.
• Dust.
• Continually populated houses.

Prevention

• Provide good environmental conditions in farrowing and weaner accommodation.
• Avoid fluctuating temperatures.
• Avoid dust.
• Maintain all-in all-out management of farrowing and weaner houses.

Treatment

• None is required.
• If sneezing and poor growth occur post-weaning, the creep can be medicated with antibiotics such as CTC, OTC, trimethoprim/sulpha or tylosin for 14 days.