Bovine Spongiform Encephalopathy in Cows: Mad Cow Disease Signs and Reporting
- See your vet immediately if a cow shows progressive neurologic signs such as poor coordination, unusual aggression, hypersensitivity, trouble standing, weight loss, or a drop in milk production.
- Bovine spongiform encephalopathy, or BSE, is a fatal prion disease of the brain and spinal cord. There is no treatment or vaccine.
- Suspect cases should be reported promptly through your vet and State or Federal animal health officials because BSE is a reportable disease in the United States.
- A live-animal diagnosis cannot be confirmed on the farm. Definitive diagnosis relies on postmortem testing of brain tissue through approved laboratories and surveillance programs.
- Typical immediate veterinary and regulatory evaluation cost range is about $0-$500 out of pocket for many producers when State or Federal surveillance support applies, but private farm-call and exam costs can still vary by region.
What Is Bovine Spongiform Encephalopathy in Cows?
Bovine spongiform encephalopathy, often called BSE or mad cow disease, is a progressive, fatal neurologic disease of cattle caused by abnormal proteins called prions. These prions build up in the central nervous system and damage brain tissue over time. As the disease advances, affected cows develop worsening behavior changes, movement problems, and eventually become unable to function normally.
There are two recognized forms. Classical BSE is linked to oral exposure to infectious prions, historically through contaminated feed. Atypical BSE is believed to occur spontaneously at a very low rate in older cattle. Both forms are serious, and there is no effective treatment or vaccine.
In the United States, BSE is rare, but it remains important because it is a reportable animal disease and has food-safety significance. If your herd veterinarian thinks BSE is a reasonable concern, the next step is not to wait and see. Your vet should help start the reporting and testing process right away.
Symptoms of Bovine Spongiform Encephalopathy in Cows
- Poor coordination or ataxia
- Hypersensitivity or hyperesthesia
- Behavior changes or aggression
- Trouble standing or rising
- Weight loss despite ongoing feeding
- Decreased milk production
When to worry: See your vet immediately if a cow has progressive neurologic signs, especially poor coordination, unusual aggression, marked sensitivity to handling, or trouble standing. BSE is not the most common cause of these signs, and conditions like rabies, listeriosis, lead toxicity, ketosis, hypomagnesemia, and polioencephalomalacia may also need urgent attention. What matters most is that a cow with slowly worsening neurologic disease should be evaluated and reported appropriately rather than monitored at home.
What Causes Bovine Spongiform Encephalopathy in Cows?
BSE is caused by misfolded prion proteins rather than bacteria, viruses, or parasites. In classical BSE, infection is associated with cattle eating feed contaminated with infectious ruminant tissues. That is why feed controls have been such an important part of prevention in the United States and other countries.
U.S. prevention efforts include a long-standing ruminant feed ban that prohibits most mammalian protein in feed for cattle and other ruminants. FDA later strengthened these protections by prohibiting certain high-risk cattle tissues, including brains and spinal cords from older cattle, in all animal feed. These rules are designed to prevent the disease from becoming established or amplified through feed.
Atypical BSE appears different. It is thought to arise spontaneously at a very low rate, usually in older cattle, rather than from the same feed-related pathway associated with classical BSE. For pet parents and producers, the practical takeaway is that prevention focuses on feed compliance, surveillance, and rapid reporting of suspicious neurologic disease.
How Is Bovine Spongiform Encephalopathy in Cows Diagnosed?
BSE cannot be confirmed by watching signs alone. Your vet will start with a neurologic exam and herd history, then consider other causes of similar signs, including rabies, listeriosis, lead poisoning, hypomagnesemia, ketosis, toxic plants, and polioencephalomalacia. One clue is that BSE usually has a slow onset and steadily progressive course.
A definitive diagnosis requires postmortem testing of brain tissue, especially tissue from the medulla oblongata. Approved testing methods include histopathology, immunohistochemistry, Western immunoblot, and validated rapid screening tests used in surveillance programs. A positive rapid test is typically followed by confirmatory testing.
In the United States, suspect animals are handled through State and Federal reporting and surveillance systems. USDA APHIS targets testing toward higher-risk cattle, including animals with central nervous system signs and cattle that are non-ambulatory, low-weight, injured, or dead. If your vet suspects BSE, they should contact the appropriate animal health authorities promptly so sampling, movement guidance, and case follow-up can happen correctly.
Treatment Options for Bovine Spongiform Encephalopathy in Cows
Spectrum of Care means you have options. Here are treatment tiers at different price points.
Budget-Conscious Care
- Immediate isolation and reduced-stress handling for a cow with progressive neurologic signs
- Prompt farm-call examination by your vet
- Reporting the suspect case through your vet to State or Federal animal health officials
- Basic herd record review, feed history review, and movement restriction guidance while the case is evaluated
- Humane euthanasia discussion if welfare or handler safety is declining
Recommended Standard Treatment
- Full veterinary neurologic assessment and differential diagnosis review
- Immediate reporting of a suspect case as required
- Humane euthanasia when indicated for welfare and handler safety
- Postmortem sample collection or coordination with approved diagnostic or regulatory channels
- Documentation of feed exposure, age, identification, offspring, and herd contacts as advised by officials
Advanced / Critical Care
- Complex case management with your vet, diagnostic laboratory, and animal health officials
- Enhanced on-farm biosecurity and movement-control planning
- Necropsy and confirmatory laboratory coordination where appropriate
- Expanded herd investigation, trace-back, and feed-source review
- Detailed documentation for regulatory, food-safety, and herd management decisions
Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.
Questions to Ask Your Vet About Bovine Spongiform Encephalopathy in Cows
Bring these questions to your vet appointment to get the most out of your visit.
- Which neurologic diseases are highest on your differential list for this cow right now?
- Do this cow's signs meet the threshold for immediate BSE reporting in our State?
- Should this animal be isolated, and what handling precautions do you want us to use today?
- What samples can be collected, and which tests require postmortem tissue?
- Are there State or Federal programs that may help cover testing or surveillance costs in this case?
- What feed records, animal ID records, and movement history should we gather now?
- Do we need to monitor related animals, offspring, or herd mates more closely?
- If this is not BSE, which treatable conditions are most important to rule out quickly?
How to Prevent Bovine Spongiform Encephalopathy in Cows
Prevention centers on feed safety, surveillance, and rapid reporting. The most important herd-level step is to follow all ruminant feed regulations and avoid any feed practices that could expose cattle to prohibited mammalian proteins or high-risk cattle tissues. Work closely with your vet, nutritionist, and feed suppliers so labels, storage, transport, and cross-contamination controls are all clear.
It also helps to keep strong records. Maintain accurate information on animal identification, feed sources, purchase history, and herd movements. If a neurologic case appears, those records can make the response faster and more precise.
Finally, do not ignore subtle neurologic changes. USDA surveillance specifically targets cattle with central nervous system signs, as well as animals that are non-ambulatory, low-weight, injured, or dead. If a cow shows unusual aggression, poor coordination, trouble rising, weight loss, or declining milk production, see your vet immediately and discuss whether the case should be reported. Early reporting protects your herd, supports national surveillance, and helps maintain food-safety safeguards.