Swine Erysipelas in Pigs: Diamond Skin Disease Signs & Treatment

Swine erysipelas, often called diamond skin disease, is a contagious bacterial infection in pigs caused mainly by Erysipelothrix rhusiopathiae. It is one of the oldest recognized swine diseases and is seen most often in growing and adult pigs, although pigs of many ages can be affected. The classic skin lesions are raised, firm, diamond-shaped patches, but not every pig develops that textbook pattern.

This disease can show up in several forms. Acute disease may cause high fever, depression, reluctance to stand, stiff walking, and sudden death. Subacute disease may be the stage where the diamond skin lesions are easiest to notice. Chronic disease can follow earlier infection and may lead to lasting arthritis, poor growth, or heart valve infection called endocarditis.

For pet parents, the biggest concern is how fast a sick pig can decline. A pig that seems tired in the morning may be much sicker by evening if the infection is affecting the bloodstream. Quick veterinary care gives the best chance for recovery, especially before chronic joint or heart damage develops.

Because this bacterium can infect people through broken skin, swine erysipelas is also a zoonotic risk. Wear gloves when handling a sick pig, cleaning pens, or touching skin lesions, and wash hands well afterward.

Swine erysipelas is caused by the bacterium Erysipelothrix rhusiopathiae. Many pigs carry this organism in their tonsils without looking sick. These healthy carriers can shed the bacteria in feces and oronasal secretions, which means a pig may be exposed from another pig that seems completely normal.

Infection usually happens when pigs ingest contaminated feed, water, or feces, or when bacteria enter through small skin abrasions. The organism can survive in the environment and remain viable in feces for months, so contaminated housing, equipment, and crowded conditions can help it spread.

Stress often plays a role in outbreaks. Heat stress, transport, mixing pigs, poor sanitation, and other management pressures can make disease more likely in exposed pigs. On farms or in multi-pig homes where the bacterium is already present, some pigs may stay carriers while others become acutely ill.

Recovered pigs can also remain carriers. That is one reason your vet may talk with you not only about treating the sick pig, but also about herd or household management, isolation, cleaning, and vaccination planning.

Your vet will start with the history and physical exam. Fever, stiffness, reluctance to move, and the classic diamond-shaped skin lesions can make swine erysipelas highly suspicious. Still, other serious pig diseases can look similar, so visual signs alone are not always enough for a final answer.

Definitive diagnosis is usually based on testing. Your vet may recommend bacterial culture or PCR from blood, spleen, synovial tissue, or other affected tissues, especially during the acute phase when finding the organism is more likely. In pigs with chronic lameness or suspected heart involvement, diagnosis can be harder because the bacteria may be less easy to isolate.

A rapid improvement after starting penicillin has historically supported the diagnosis in acute cases, but response to treatment should not replace proper veterinary evaluation. Your vet may also consider other causes of fever, skin lesions, lameness, or sudden death, including other infectious and foreign animal diseases that require prompt attention.

If a pig dies suddenly, your vet may recommend necropsy and laboratory testing. That can help confirm the cause, guide treatment for other exposed pigs, and shape prevention steps going forward.

Prevention usually centers on vaccination, sanitation, and stress reduction. Merck Veterinary Manual notes that vaccination against Erysipelothrix rhusiopathiae is very effective for controlling outbreaks. Your vet can help decide the right schedule based on your pig's age, lifestyle, and whether you have a single pet pig or a group setting.

Good hygiene matters because the bacterium can spread through contaminated feces, feed, water, and surfaces. Regular pen cleaning, dry bedding, clean water, and prompt removal of manure lower exposure pressure. Isolating pigs with fever, skin lesions, or lameness can also help reduce spread while your vet works on a diagnosis.

Reducing stress is another practical step. Overcrowding, transport stress, heat stress, and sudden mixing of pigs can all increase the chance that carrier pigs start shedding more bacteria or that exposed pigs become sick. A steady routine, good ventilation, and careful introductions can help.

If your pig has been treated for erysipelas, ask your vet about follow-up monitoring and whether vaccination is appropriate later. Vaccines should not be given during antimicrobial treatment because antibiotics can interfere with the immune response. Also remember the human health side: wear gloves when handling sick pigs or cleaning contaminated areas, especially if you have cuts on your hands.