Porcine ear necrosis syndrome (PENS) is a disease of swine characterized by the large erosive lesions on the pinna or outer structure of the ear (Fig 1). PENS has two distinct clinical patterns: In the milder form, the lesion remains as a localised, narrow, encrusted sore(s) along the ear tip, causing little discomfort to the pig or concern to the producer. These localised encrusted lesions usually evolve slowly to produce either slight 'flaking' of the external ear margin or resolve with no obvious necrosis. In the more acute form which is becoming increasingly prevalent on farms, the lesions become much more severe and are associated with an acute inflammatory response, ulceration of the epidermis and development of a large, irregular necrotic lesion along the margin of the ear.
The clinical symptoms of ear necrosis are usually caused by poor blood flow to a vast network of blood vessels at the tip of the ear (Fig. 2) resulting in insufficient supply of critical nutrients to cells. The blackening of the skin that is characteristic of PENS (Fig. 3) is caused by deoxygenation of haemoglobin in the red blood cells which cause the cells to die. As the cells are dying, the immune system releases small proteins called cytokines, which promote inflammation. This inflammation causes the blood vessels around the necrotic lesions to dilate, which leads to the dusky grey-red colour of the surrounding skin. As mentioned above when the cells die the damaged skin flakes away leading to the development of 'oozing' sores (Fig. 4). These sores present the opportunity for systemic spread of ear necrosis as well as secondary infections.
While the cause of clinical necrosis of the ear is known, the exact root cause of PENS on farms is less well defined: Many contributory factors for the development of PENS have been suggested and although these can be divided into infectious and non-infectious agents, no definitive root cause has been identified. For example, in a study by Osweiler et al., from 2016, mycotoxins were seen as a contributory factor. Other authors have reported that changes in blood constituents such as fibrin are related to skin necrosis. In another more recent study conducted in 2012 by Weissenbacher-Lang, to determine the time course of the necrosis development, alterations in bacterial profiles on piglet ear tissue were analysed. In the study, increased concentrations of both Streptococcus and Staphylococcus bacteria were isolated from early and advanced lesions. 
The relevance of this is that in pigs, Staphylococci are adapted to live on normal skin and can be considered a causative agent of early skin lesions however, the invasion of Streptococci must be preceded by damage of the skin due to infection or trauma. In this study the authors observed that both kinds of bacteria can appear at different stages of disease independent of the progression of the disease, thus underlining the multifactorial nature of the disease.
Due to the multifactorial nature of Porcine Ear Necrosis Syndrome, we must adopt a multi-factorial approach when planning and developing control strategies. From a management point of view, we should try to incorporate practices that minimize pig directed behaviours and aggression. Things to consider in this context include:
The Global R&D team at Devenish have developed Klenear as a solution to alleviate & help prevent porcine ear necrosis syndrome. Klenear is a unique blend of natural ingredients of high bioavailability that act synergistically to alleviate the negative effects of ear necrosis. Klenear has been carefully designed to work on all the factors that give rise to ear necrosis. The unique mix of ingredients targets all known elements involved in the onset of ear necrosis and also includes elements to aid the healing of skin tissue associated with an outbreak. Recent research conducted has demonstrated the beneficial effects of Klenear in reducing the incidence of porcine ear necrosis syndrome in growing pigs. For further information contact your Devenish representative.
