The Porcine Respiratory Complex
Pig breeding is one of the most important sectors of livestock, both in terms of production and sales. That’s why studying the diseases that affect these creations is so important. Among them, the porcine respiratory complex stands out.
General information about the Porcine Respiratory Complex
Since the 20th century, many infectious diseases are no longer understood as being produced by a single microorganism, being referred to as multifactorial complexes. Among swine, one of the most relevant polymicrobial diseases is the swine respiratory complex – CRS, from now on -, which include:
- The SRRS virus – Swine Reproductive and Respiratory Syndrome.
- Aujeszky’s illness.
- The Influenza Virus.
- The Porcine Respiratory Coronavirus.
- The Circovirus.
- Mycoplasma spp.
- Bordetella spp. , Pasteurella spp. …
- Haemophilus spp. , Streptococcus spp., Escherichia coli …
There are several pathogenic mechanisms that favor this type of disease, such as:
- Synergies between different agents.
- Blocking the immune system .
- Changes in the respiratory mucosa.
- Metabolic, physiological and physical changes.
- The release of inflammatory components that increase the severity of the disease.
Description of the porcine respiratory complex
This disease is one of the most complex clinical conditions and has the greatest negative impact on swine rearing.
It is a very common pathology on intensive pig farms, although it also occurs, to a lesser degree, on extensive farms. It causes considerable economic losses, resulting from the delay in fattening the animals and the multiple sacrifice needs.
Primary pathogens
Within the CRS there are primary pathogens capable of altering defense mechanisms and establishing themselves in the swine host by itself. If they are the only pathogens involved in the disease, it usually disappears within a short time.
The problem lies in the complications developed because of the presence of secondary or opportunistic pathogens. This generates much greater economic losses.
opportunistic pathogens
The rest of the pathogens are considered “opportunistic”, as they take advantage of the virulence factors of the previous ones to also trigger a disease.
Thus, depending on the interactions and the complexity of the process, some microorganisms can behave both as “primary” agents and as “opportunists”. But others are unequivocally linked to one of the two categories.
The evolution of the porcine respiratory complex
During the last 30 years, there have been substantial changes in pig production. We moved from extensive production to the proliferation of intensive breeding farms with a high density of animals. And this favors the spread of respiratory diseases.
Factors that favor the onset of the disease
First, overcrowding, along with a lack of ventilation, become powerful stress allies. Second, there are high levels of dust and ammonia, which have a negative impact on the respiratory system of pigs.
And thirdly, there are other negative factors, such as the constant flow of animals, with the arrival and departure of individuals constantly, thus aggravating the spread of disease. Furthermore, most respiratory pathogens have a cosmopolitan distribution, and it becomes almost impossible to find a lot of animals completely free of them.
Critical moments for the porcine respiratory complex
Even when sanitary conditions are maximized, there are critical moments for the complex’s emergence. For example, when maternal immunity declines – after weaning – at which point piglets are more susceptible to contagion.
In turn, diseases can enter the creation through vectors, new animals, wild animals and even through the farm employees themselves.
Conclusion
To conclude, the multifactorial etiology of CRS can vary, not only between countries, but also between different production systems. And, within the same farm, it can vary over time. Therefore, its study is highly complex, although necessary.
