A discussion on the issue of piglet diarrhoea
In recent years, diseases related to piglet diarrhoea have become an important issue in China's swine industry. Since the end of 2010, swine epidemic diarrhoea has spread across the country, with the earliest symptoms of vomiting followed by diarrhoea appearing in piglets five hours after birth. The mortality rates are: within two days of age, 100%; two to five days of age, 45%; after nine days of age, about 18%. The younger the piglets; the higher the mortality rate. For some swine farms, epidemic diarrhoea continues to be prevalent, resulting in huge losses.
So how can one determine the cause of epidemic diarrhoea, and scientifically and effectively prevent and control the disease, so as to reduce the huge economic losses?
Swine diarrhoea can have a variety of causes, including poor sow feeding and management, inadequate disinfection of diseased pigs, pregnant sows acting as a disease carrier, contamination of the housing environment (by people, equipment, vehicles etc.), and inadequate anti-inflammatory treatment of postpartum sows. The effectiveness of current vaccines on the market is controversial. Nonetheless, the three main causes of swine diarrhoea are temperature and humidity stresses, pathogens (fungi, bacteria and viruses), and parasites (Coccidia and Balantidium coll etc.).
Different causes of piglet diarrhoea would often manifest certain age characteristics, and familiarity of various diseases at specific ages would be very helpful in accurate diagnosis. As examples, for one to three days of age, pseudorabies, clostridial enteritis and hypoglycaemia should be considered as causes of piglet diarrhoea. For one to 35 days of age, 'yellow-white' scours associated with E. coli can occur. In general, severe acute diarrhoea from one day of age is a symptom of epidemic diarrhoea or infectious gastroenteritis.
A necropsy can further determine the cause of swine diarrhoea. First are the mesenteric lacteals. Observe whether there are fatty deposits. If these are lacking, consider viral gastroenteritis or hypoglycaemia caused by inadequate sow suckling. Next observe whether the serosa of the small intestine is reddened (clostridia infection) or transparent (viral gastroenteritis). Finally observe whether the mucosal surface of the small intestine shows blood spots or obvious bleeding (clostridial enteritis, salmonellosis).
Once piglets have diarrhoea, it is first necessary to have an accurate diagnosis. Both the symptoms of and the root cause of the disease should be dealt with, and improvements should be made in feeding and management practices.
With regard to bacterial-induced diarrhoea, colibacillosis often occurs on swine farms with poor management and environmental hygiene. Providing pigs with a warm and dry environment is key to the prevention and control of colibacillosis. Coupled with good quarantine measures, this prevents the disease from various infection sources. It is also important to select quality piglet feed, to ensure that the E. coli count stays within a normal range.
With regard to viral-induced diarrhoea, there are three main types in terms of prevention and control: epidemic diarrhoea; infectious gastroenteritis; rotavirus. Although the current vaccines on the market have a certain preventive effect in sows, they basically have no effect in neonatal piglets. It is often seen that an entire group of suckling piglets suffer from an acute form of the disease, and ironically infect the sow, resulting in reduced feed consumption and even diarrhoea. From the observation that maternal antibodies from sow colostrum do not protect piglets from diarrhoea, it can be concluded that parenteral vaccination in sows is ineffective. However, it is also observed that infected piglets which recover have strengthened immunity, highlighting that there is a process towards immune development, and the exact mechanisms are worth to be further studied. As infection can occur as early as one day of age, when oral vaccination is ineffective, it is often difficult to take any appropriate action when disease strikes, and this remains the biggest issue on swine diarrhoea. Some experts recommend creating in-house vaccines from samples taken from the small intestine of infected piglets, and inject these in sows 40 and 20 days before birth. I am personally sceptical of this recommendation, and believe that the only effective way is to cut the chain of disease transmission in piglets.
For diarrhoea associated with coccidiosis, it is necessary to ensure good environmental hygiene, and administer oral anticoccidial drugs for infected piglets.
With the development of the swine industry, diseases have also become more severe and complex, bringing considerable challenges to veterinary workers in terms of prevention, diagnosis and treatment.
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Article made possible through the contribution of LI An-ming, DVM, staff writer at eFeedLink