Neonatal mortality

Occurrence: Worldwide.
Age affected: Newborn.
Causes: Mismanagement; overlying; infections.
Effects: Significant if >3% die within 24 hours.

Causes

Newborn piglets may die for a number of reasons and up to 3% of piglets born alive may die in the neonatal period in a normal herd. Death may occur in the period between clearing the membranes after birth and the first feed. There may be partial expansion of the lungs and subsequent respiratory difficulty resulting in death. Navel bleeding may occur. Congenital conditions such as splay leg or tremor may prevent feeding and underweight piglets (800g or less) may fail to find a teat. These animals may die of starvation and hypoglycaemia and death is more likely in cold conditions.

Starvation may also result from maternal failure in agalactia or mastitis. Piglets which cannot escape the sow may be crushed. Those piglets which have taken inadequate amounts of colostrum are likely to develop infections and neonatal septicaemia and neonatal diarrhoea caused by E. coli may occur within the first 24 hours of life and kill the piglet shortly afterwards.

Death from Clostridium perfringens type C infection may occur at 36-48 hours of age and mortality from a number of systemic diseases can occur at this stage. PED, TGE, vomiting and wasting disease, streptococcal septicaemia and Actinobacillus suis septicaemia can all kill neonatal piglets.

Mode of transmission

Some causes of neonatal mortality are infectious, and the mode of transmission depends on the identity of the disease concerned. Others, such as partial lung expansion and the consequences of agalactia are managemental and will recur when farrowing sows and young litters are not closely monitored. Congenital conditions may have a genetic cause and be vertically-transmitted.

Clinical signs

Weak piglets which have escaped from the afterbirth are often found collapsed, unable to join the remainder of the litter at the udder. Those with partial expansion of the lungs have high respiratory rates with shallow breathing. Those with splay leg are often vigorous at first but may have difficulty in reaching the udder and competing for teats. The clinical signs of hypoglycaemia develop, ending in coma and death.

Many of these weak piglets are underweight with body weights less than 800 g and may wander aimlessly looking for food. Normal piglets may lose condition, develop hypoglycaemia and die if agalactia is present in the sow, if there are too many piglets for the number of teats available or if the temperature is so low that chilling takes place. After colostrum has been taken, agalactia or mastitis in the sow may occur and cause neonatal mortality. Diseases such as E. coli or A. suis septicaemia cause affected piglets to stand aside from the litter with drooping tails, erect hair coats and eventually go into sternal recumbency and die. Neonatal diarrhoea due to E. coli or C perfringens type C is usually obvious. Crushing may be signalled by squealing, or damaged piglets may be found alive.

The occurrence of neonatal mortality is easily identified by the presence of dead piglets unless these have been removed by predators/scavengers or by other workers prior to recording.

It is necessary to distinguish between neonatal deaths and those which occur during parturition. When piglets have escaped the membranes, the cartilaginous tips to the toes wear away to leave a hoof. If the tips are still present, then piglets have not walked and should be classed as intrapartum deaths. Where neonatal mortality occurs in closely observed units, the clinical signs leading to it may indicate the cause or clinical inspection of the sows and litter may reveal the cause.  

Postmortem lesions

Dead piglets are a major source of information as to the cause of the mortality. Those which are undersize can be identified by weighing, those which have never eaten can be identified by the lack of milk curd and presence of clear fluid in the stomach and partially-expanded lungs can also be identified. Splay leg is detectable in dead piglets by the ulcers and scrapes on the base of the tail and around the anus where the animals has dragged itself on the ground and crushing, septicaemia and enteritis can also be detected.

Treatment and prevention

Treatment of remaining members of affected litters is possible and consists of support in terms of warmth, ensuring that colostrum is given to weak piglets (by stomach tube if necessary) and subsequent feeding either by fostering or artificially. Piglets which are too small to be viable should be killed humanely as should those too compromised by congenital damage or injury. Specific disease such as septicaemia and enteritis can be treated by injection or orally.

Prevention of neonatal mortality requires the correction of any husbandry features which lead to deaths such as placement of the lamps post-farrowing, the environmental temperature for the piglets and assistance to weak or compromised piglets on a regular basis. Attended farrowing and assistance with colostral intake often lead to increased survival rates.

Where splay leg is a problem, the hind legs can be taped to allow piglets to stand and where crushing is a problem, the design of the farrowing crate can be assessed and corrected or blowaway units installed to reduce losses. Disease such as mastitis in sows should be promptly treated and neonatal disease in the piglet such as E. coli and C. perfringens type C enteritis treated promptly or prevented by maternal vaccination.