Shipping fever is a respiratory illness in cattle triggered by the stress of transport, weaning, and environmental change. It’s the most common and costly disease in feedlot operations, responsible for 60% to 90% of all sickness and death in feedlots and costing the U.S. beef industry over $1 billion per year. The formal name is bovine respiratory disease complex (BRD), and understanding how it develops is key to preventing it.
Why It’s Called Shipping Fever
The name comes from the disease’s strong link to transportation. When calves are hauled from pasture to an auction yard and then to a feedlot, the combination of physical stress, dehydration, exhaustion, and exposure to unfamiliar animals creates the perfect conditions for respiratory infection. The journey itself is only part of the problem. Calves are often weaned, vaccinated, and loaded onto trucks within a short window, stacking multiple stressors on top of each other.
Stress triggers the release of glucocorticoids, the body’s natural stress hormones. These hormones dampen the immune system by dialing down inflammatory signaling and reducing the number of infection-fighting white blood cells in circulation. With the immune system compromised, bacteria that normally live harmlessly in a calf’s nasal passages can migrate deep into the lungs and multiply unchecked. Interestingly, recent research from cattle transported after auction found that the airway response can also swing in the opposite direction, producing excessive inflammation even without detectable pathogens, which suggests the immune disruption from transport is more complex than simple suppression.
The Pathogens Involved
Shipping fever isn’t caused by a single germ. It’s a complex involving multiple viruses and bacteria working together. Viruses typically strike first, damaging the lining of the respiratory tract and opening the door for bacterial infection. The most common viral players are bovine viral diarrhea virus (BVDV), bovine respiratory syncytial virus, bovine herpesvirus 1, and parainfluenza 3 virus.
The bacterial infection that follows is what usually makes calves severely ill. A study of 68 cattle that died from the disease in North American feedlots found that the bacterium Mannheimia haemolytica was present in 91% of cases and BVDV in 69%, with both occurring together in 63% of animals. Mannheimia haemolytica is especially dangerous because it causes acute, severe pneumonia with rapid tissue destruction in the lungs. Other bacteria involved include Pasteurella multocida (found in about 13% of fatal cases), Histophilus somni, and Mycoplasma bovis.
Signs to Watch For
Shipping fever typically shows up within the first few weeks after cattle arrive at a new facility. The hallmark sign is fever, with a body temperature above 39.5°C (about 103°F). In more severe cases, core temperature can climb above 40°C (104°F). Along with fever, affected cattle show a predictable cluster of symptoms: loss of appetite, lethargy, nasal and eye discharge, and coughing.
As the disease progresses, breathing becomes rapid and labored. In severe cases, cattle may breathe with their mouths open. Behavioral changes are also telling. Sick calves are less likely to approach people or investigate new objects, showing a general decline in alertness. They drink more slowly and move less, a pattern sometimes called “sickness behavior,” where the animal conserves energy to fight infection. These behavioral shifts often appear before the most obvious respiratory signs, making close observation in the days after arrival especially important.
Detecting the disease early matters enormously, because lung damage accumulates quickly and becomes irreversible. Traditional diagnosis relies on visual observation by experienced handlers, but this misses a significant number of cases, particularly subclinical infections where calves look fine on the outside while their lungs are already compromised. Thoracic ultrasound has emerged as a more accurate tool, allowing real-time imaging of lung tissue to detect consolidation and fluid buildup that visual assessment alone would miss.
How Shipping Fever Is Treated
Antibiotics are the primary treatment because the life-threatening phase of the disease is bacterial pneumonia. Several classes of antibiotics are approved for BRD treatment in the United States, broadly grouped into two categories: those that kill bacteria directly (bactericidal drugs, including beta-lactams and fluoroquinolones) and those that stop bacteria from multiplying (bacteriostatic drugs, including macrolides, phenicols, and tetracyclines).
Most calves respond to their first round of treatment, but roughly 15% of cases require a second course with a different type of antibiotic. The choice of drug class matters for long-term outcomes. Data from feedlot operations shows that calves treated with two rounds of bactericidal antibiotics had about a 50% chance of needing additional treatment, while calves that received a bacteriostatic drug first followed by a bactericidal drug had a roughly 74% chance of needing further treatment. This suggests that aggressive early treatment with the right drug class can reduce the cycle of repeated illness.
Even with successful treatment, cattle that have had shipping fever often perform worse over the long term. They gain weight more slowly, and the lung scarring from pneumonia can permanently reduce respiratory capacity. Prevention is far more effective than cure.
Prevention Through Preconditioning
The single most effective strategy against shipping fever is preconditioning, a management program that prepares calves for the stress of transport before they leave the ranch. A standard preconditioning protocol includes three elements: weaning calves at least 45 days before sale, training them to eat from a feed bunk and drink from a water trough, and completing a full vaccination program.
Vaccination timing varies by operation. Some producers vaccinate calves 2 to 4 weeks before weaning, then give booster shots at weaning. Others give the first round at weaning and boosters 2 to 4 weeks later. Either approach ensures the calf’s immune system has time to build a response before it faces the stress of transport and exposure to new animals. Vaccines typically target the major viral agents (BVDV, bovine herpesvirus 1, parainfluenza 3, and bovine respiratory syncytial virus) along with bacterial components.
The 45-day weaning period is critical. Calves that have already adjusted to life without their mothers, learned to eat on their own, and recovered from the stress of weaning are dramatically more resilient when loaded onto a truck. Freshly weaned calves shipped directly to auction face the compounded stress of separation, hunger, transport, and commingling with potentially sick animals all at once.
Why It Costs So Much
The economic damage from shipping fever extends well beyond the cost of antibiotics. For pre-weaned dairy calves, the average short-term cost per sick calf is around $42, covering medicine and labor. But when you factor in reduced growth, longer time to market weight, and lower carcass quality, the true cost of a single case in the first 120 days of life climbs to $252 to $282 per animal. Multiply that across the roughly 0.64% to 0.74% of cattle on feed in North America that die from the disease each year, plus the much larger percentage that get sick and survive with reduced performance, and the billion-dollar annual figure becomes easy to understand.
For ranchers, the financial incentive to precondition is clear. Buyers at auction consistently pay more for preconditioned calves because they know those animals are less likely to get sick, need treatment, or die in the feedlot. The upfront cost of a 45-day preconditioning program is a fraction of the losses a single outbreak of shipping fever can cause in a pen of newly arrived cattle.