ThePigSite Pig Health
Definition of Health and Disease(30) The term "Health" means different things to different people. Absence of diseases is clearly a prerequisite but in pigs it means more than that. It is a state of physical and psychological well-beings that allows the pig to express its genetic potential for maximising productivity, reproductive performance and lean meat production.
The term "disease" means an unhealthy disorder of body and mind, sometimes with pain and unease, that is likely to prevent the pig from exploiting its genetic potential resulting in lowered productivity.
The level of clinical disease is described by the term morbidity. Disease can be clinical (i.e. the affected pig shows clinical signs) or sub-clinical (the affected pig shows no obvious clinical signs). Sub-clinical disease can also have an adverse affect on productivity. You should distinguish between sub-clinical disease and sub-clinical infection,. Every healthy herd, without exception, carries a multitude of potentially pathogenic infections, mainly in the gut but also in the nose, throat, skin and genitals, which are not causing disease either clinical or sub-clinical.
There is a delicate balance between these potential pathogens and the pigs' immunity to them. Any physical or psychological disturbance of this immunity may render the pig susceptible.
Good husbandry, including good stockmanship aims to avoid such disturbances, provided the more virulent diseases are absent (e.g. atrophic rhinitis, TGE). Good husbandry means good housing, good nutrition and good management. Good stockmanship means care and attention to the pig's health and welfare.
This delicate balance between potential pathogens and the pigs immunity becomes even more precarious on a herd basis. By causing disease in small groups of pigs as a result of poor husbandry, the pathogenic organism multiplies up to a concentration that may overcome the more resistant pigs. The concentration again builds up and threatens to overwhelm the collective immunity of the herd (i.e. herd immunity). (Fig.2-0)