If you are starting to notice crusty or black ear tips in your herd, it is time to take a closer look at both pig behavior and your feed bin.
Ear tip necrosis (ETN), also known as porcine ear necrosis (PEN), is a painful condition that causes ear tissue to progressively rot. While the disease itself is rarely fatal, the fallout is costly.
“The infection is painful, affects growth and meat production, and often leads to injudicious use of antibiotics,” says Dr. Matheus Costa, an associate professor at the University of Saskatchewan’s Western College of Veterinary Medicine.
What Causes ETN?
For decades, the exact cause of ETN remained a mystery. However, research by Costa and his team, published in the scientific journal PLOS ONE, identified the bacterium Fusobacterium necrophorum as the primary causative agent.
Commonly found in the pig’s mouth and gastrointestinal tract, the bacteria follow an “outside-in” path of infection. When pigs bite or chew on ears—frequently driven by boredom, social dynamics or environmental stressors—the bacteria transfer via saliva into microlesions on the skin.
Because boredom and pen competition drive this chewing behavior, Costa emphasizes that environmental enrichment and animal welfare are central to preventing the spread of ETN.
“We don’t fully understand [pig ear necrosis] yet,” Costa noted in a university release. “There’s a lot of research to be done about disease pathogenesis and progression... [but] there are many, many different venues this research will impact when it comes to the swine industry.”
Managing Harvest-Time Triggers
While bacteria deliver the final blow, nutritional and environmental stressors often set the stage. If black ear tips spike around harvest, the problem may be linked to new-crop corn and soybean meal, notes Dr. Steve Patterson of Passion for Pigs Veterinary Service.
Patterson explains that molds in new-crop grain can produce mycotoxins. Once ingested, these toxins can contribute to problems like ETN, as he shares in a recent reel on social media.
Ingesting mycotoxins can weaken a pig’s immune defense and damage the animal’s intestinal or oral mucosal lining, making it easier for opportunistic bacteria to take hold. Feed-related discomfort also heightens restlessness and pen vice behaviors like ear-biting.
Patterson advises producers to test incoming grain right out of the field: “Make sure that you’ve got the right binder in the feed for whatever toxins you might have.”
Beyond feed quality, Patterson encourages producers to evaluate pig hydration (e.g., water flow, water quality and accessibility).
“Double-check your water flow and that you have enough nipples or cups for the number of pigs in the pen,” he advises.
Patterson also recommends evaluating the environment (e.g., square footage and ventilation systems) and feed space availability, as well as ruling out infectious agents that may be compromising the immune system.
Read more about Costa’s research in the scientific journal PLOS One.
