Tiger Heart Calf Deaths Surge as FMD Outbreaks Deepen Crisis for South African Farmers

South African livestock producers are reporting a sharp increase in sudden calf deaths linked to a condition known as tiger heart. The surge is closely associated with active foot-and-mouth disease outbreaks and is hitting unvaccinated herds the hardest. Losses are escalating fast, with young animals dying without warning.

Videos circulating among farming communities show producers burying large numbers of calves, highlighting the scale of the losses. Veterinarians and industry consultants say the pattern is consistent across affected regions. Tiger heart cases are appearing at levels never seen before in herds that have tested positive for FMD.

Tiger heart is not a disease diagnosis. It is a descriptive post-mortem finding. During examinations, the heart muscle shows alternating pale and dark striping that resembles a tiger’s coat. This appearance reflects extensive damage to the heart muscle that occurred before death.

What makes the situation more severe is how sudden the deaths are. Many calves appear healthy and active only hours before they collapse and die. There are often no visible warning signs that allow farmers to intervene.

Veterinary reports show that suckling calves are the most affected. Losses are concentrated in animals between two and nine months old. Both beef and dairy calves are dying in significant numbers. The problem has intensified because the current FMD surge coincides with peak calving periods in many beef-producing areas.

Veterinarians investigating the deaths say the common factor in most cases is active FMD infection in the herd. Young animals frequently do not show classic signs of foot-and-mouth disease such as mouth lesions, excessive salivation or lameness. Instead, the virus attacks the heart and lungs, leading to rapid deterioration and death.

Multiple strains of the FMD virus are circulating in South Africa, and the disease is now regarded as endemic in large parts of the country. Calves under three months of age are particularly vulnerable due to immature immune systems that struggle to cope with viral infection.

Consultants working with producers describe the current losses as catastrophic. Emma Niland, a dairy and beef consultant at Intelact, says the scale of the outbreak is unlike anything she has seen in her career. She reports that foot-and-mouth disease is spreading rapidly, with thousands of calves and pigs dying. Tiger heart is a sudden killer and there is no treatment available once calves are affected.

Intelact represents milk producers responsible for about 54 percent of KwaZulu-Natal’s milk production, giving the consultancy a broad view of conditions across the province. Niland says the appearance of tiger heart at this scale is new and deeply alarming. In her experience, it has only occurred in FMD-positive herds. She believes urgent mass vaccination is the only way to stop further losses.

Veterinarians stress that tiger heart itself is not a new finding. Similar heart damage has been observed in the past with black quarter, severe vitamin E and selenium deficiencies, heavy parasite burdens that cause anaemia, and certain toxic or nutritional stresses. What is different now is the scale of the problem and the underlying cause.

In the current outbreak, viral damage from FMD appears to be the primary driver rather than bacterial disease or nutritional deficiencies. Experts have also dismissed claims circulating on social media that link the deaths to grazing practices, lawn treatments or environmental toxins.

The risk is not limited to calves. Piglets, lambs and kids are also highly susceptible to the FMD virus. Once infected, there is currently no effective treatment to prevent death in these young animals.

Industry consensus is clear. Prevention is the only effective response. Recommended measures include strict biosecurity, comprehensive clostridial vaccination programmes, adequate mineral supplementation with a focus on selenium and vitamin E, and strong parasite control to reduce additional stress on young animals.

However, veterinarians and producers agree these measures are not enough without access to FMD vaccines. Vaccine shortages and delays are widely blamed for worsening the situation. Niland argues that the state must either supply vaccines or allow farmers to access them directly, as is done with brucellosis vaccines. Without sufficient vaccination, many believe the outbreak will continue for years.

The economic impact on beef and dairy producers is severe. Calves represent future breeding stock and income. Sudden deaths undermine herd rebuilding plans, disrupt cash flow and threaten long-term farm viability. The emotional toll is also heavy, with many farming families reporting distress and helplessness as animals die despite careful management.

While authorities have indicated that vaccine availability may improve, producers remain anxious as mortalities continue. Veterinarians warn that until effective vaccination programmes are rolled out at scale, tiger heart deaths linked to foot-and-mouth disease are likely to persist, especially in herds with young unvaccinated stock.