Mulberry Heart Disease in Pigs

Mulberry heart disease is a sudden, often fatal heart condition seen most often in young, rapidly growing pigs. It is grouped with nutritional myopathies and is classically associated with low selenium and/or vitamin E status. The name comes from the dark red, blotchy appearance the heart can have at necropsy because of hemorrhage on the heart surface.

In many cases, the first sign is sudden death. Some pigs may show short-lived warning signs such as weakness, breathing trouble, or collapse after stress or exercise. Merck Veterinary Manual notes that affected pigs are commonly 2 to 16 weeks old, losses are often sporadic, and death is frequently sudden and precipitated by exercise.

For pet parents with a companion pig or small backyard group, this can feel especially shocking because a pig may seem normal shortly before becoming critically ill. Even though the disease is often linked to nutrition, your vet still needs to consider other causes of sudden death in pigs, including edema disease, iron-related problems in young piglets, infectious heart disease, and toxic exposures.

Mulberry heart disease is most strongly associated with inadequate selenium and/or vitamin E. These nutrients work together as part of the body’s antioxidant defenses. When levels are too low, heart and skeletal muscle can be damaged by oxidative injury. Merck Veterinary Manual identifies mulberry heart disease and hepatosis dietetica as conditions associated with diets low in selenium or vitamin E.

Feed quality matters. Vitamin E levels can fall as feed ingredients age or are stored, and selenium content in grains and forages varies by region and formulation. Merck’s swine nutrient tables list selenium at 0.15 ppm and vitamin E at 44 IU/kg in sow diets, which helps show how carefully these nutrients are managed in balanced rations.

That said, the full picture may be more complicated in some outbreaks. Published research has reported pigs with mulberry heart disease lesions despite liver selenium and vitamin E values within expected ranges, which suggests that stress, growth rate, feed handling, or other biologic factors may also play a role in some cases. Your vet may therefore treat this as a nutrition-linked syndrome while still looking for additional contributors.

Stress can make a bad situation worse. Handling, transport, crowding, fighting, or sudden exertion may trigger collapse in a pig whose heart is already vulnerable.

Diagnosis usually starts with history and pattern recognition. Your vet will ask about the pig’s age, growth rate, recent feed changes, mineral and vitamin supplementation, stress events, and whether other pigs have died suddenly. Because many pigs die quickly, diagnosis often depends heavily on necropsy findings rather than a long list of clinical signs.

At necropsy, your vet or a diagnostic lab may find hemorrhages on the heart that create the classic “mulberry” appearance. Histopathology can help confirm muscle damage and rule out look-alike conditions. Differential diagnoses may include edema disease, iron toxicosis in newborn piglets, encephalomyocarditis, toxic causes, and other sudden-death syndromes.

Your vet may also recommend feed analysis, liver or tissue mineral testing, and review of the ration formulation. These steps matter because treatment and prevention are often herd-based, not only focused on the individual pig. Iowa State University’s Veterinary Diagnostic Laboratory lists livestock necropsy base fees around $50, with additional submission and testing charges depending on the case, so confirmation is often more accessible than many pet parents expect.

Prevention centers on balanced nutrition and good feed management. Work with your vet and, when needed, a swine nutrition professional to make sure the ration provides appropriate selenium and vitamin E for the pig’s life stage. Merck nutrient tables list selenium at 0.15 ppm and vitamin E at 44 IU/kg in sow diets, and commercial swine feeds are typically formulated with these targets in mind.

Store feed properly and use it while it is fresh. Vitamin E can decline with storage, and homemade or poorly balanced rations may not provide dependable micronutrient levels. If you keep pigs as companions or on a small farm, avoid assuming that a general livestock feed or table scraps will meet swine vitamin and mineral needs.

Reduce avoidable stress, especially in fast-growing young pigs. Rough handling, overcrowding, transport, fighting, and sudden exertion may trigger collapse in vulnerable animals. If your area has low-selenium soils or your herd has had a previous case, ask your vet whether preventive supplementation or a feed review is appropriate.

If one pig dies unexpectedly, prevention for the rest of the group starts with getting answers quickly. A timely necropsy, ration review, and your vet’s herd plan can help prevent repeat losses.