Bovine Respiratory Disease (BRD) is a complex illness impacting cattle globally. It is one of the most common and expensive diseases in the industry. BRD is not caused by a single agent but results from viral and bacterial pathogens interacting with environmental stressors and the animal’s immune system. Viruses often initiate the disease by damaging the respiratory tract lining, allowing opportunistic bacteria like Mannheimia haemolytica and Pasteurella multocida to cause severe pneumonia. Stressors such as transportation, weaning, and commingling suppress the animal’s defenses, making them susceptible to this multifactorial disease.
Recognizing the Signs of BRD
Identifying BRD early is the most important factor for a successful treatment outcome. Affected cattle instinctively hide signs of illness, so they must be observed closely for subtle behavioral changes. Early intervention prevents the progression to chronic disease and irreversible lung damage.
Early signs of BRD are often non-specific. Initial indicators include mild depression, lethargy, a sleepy appearance, and a reduced interest in surroundings or feed. Fever is frequently one of the earliest measurable signs, with body temperatures often rising above the normal range of 100.4°F to 102.8°F (38.0°C to 39.3°C).
As the disease progresses, respiratory symptoms become more apparent. Advanced signs include a deep, wet cough, rapid or labored breathing, and thick, purulent nasal and ocular discharge. Severe depression, a sunken-eye appearance due to dehydration, and a complete lack of appetite indicate a serious bacterial infection. A veterinarian must confirm the diagnosis before treatment is initiated to ensure the appropriate protocol is selected.
Pharmaceutical Treatment Protocols
Treatment focuses on eliminating the bacterial infection and managing associated pain and inflammation. Antibiotics are the foundation of this protocol because secondary bacterial invaders cause the severe illness and lung damage characteristic of BRD. A veterinarian must select the antibiotic, considering the farm’s history of antimicrobial resistance and the drug’s activity against common BRD pathogens like Mannheimia haemolytica and Histophilus somni.
Antibiotics are typically chosen from classes such as macrolides (e.g., tulathromycin) or phenicols (e.g., florfenicol). These drugs are effective and often provide long-lasting therapeutic concentrations in the lung tissue from a single injection. Florfenicol and tulathromycin are often preferred as first-line treatments over antimicrobials important to human medicine to promote responsible drug stewardship. The veterinarian determines the correct dosage and route of administration to ensure maximum efficacy while adhering to mandated withdrawal times.
Adjunctive therapies are administered concurrently with antibiotics to improve comfort and recovery speed. Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), such as flunixin meglumine, reduce fever, pain, and systemic inflammation. By lowering the fever, NSAIDs help restore appetite and reduce the energy the animal expends on thermoregulation. Combining an appropriate antibiotic with an NSAID targets both the causative bacteria and the debilitating symptoms of the disease.
Essential Supportive Care
Medication alone is generally insufficient for a complete recovery, making supportive care equally important. Sick animals should be calmly isolated in a dedicated hospital pen to minimize stress and prevent the spread of infectious agents. Low-stress handling techniques are necessary during movement and treatment because minimizing anxiety supports the animal’s immune function.
Environmental management of the isolation area must prioritize clean, dry, and well-ventilated conditions. Proper airflow is necessary to remove airborne pathogens and noxious gases without creating direct drafts that can further stress the sick animal. Providing fresh, deep bedding is a simple measure to keep the animal dry and comfortable, supporting its ability to rest and recover.
Nutritional support and hydration are important for animals with high fevers and reduced appetites. Fresh, clean water must be continuously available, and severely ill animals may need supplemental oral rehydration fluids to combat dehydration. Offering highly palatable feed, such as fresh hay or a softer ration, encourages the animal to eat, providing the necessary energy to fuel the immune response and tissue repair.
Monitoring Treatment Effectiveness and Recovery
Careful observation is required after treatment begins to determine if the protocol is successfully resolving the infection. A positive response is typically indicated by a noticeable drop in the animal’s rectal temperature within 24 to 48 hours. The return of appetite and increased alertness are also strong indicators of improvement.
If the animal shows no improvement or its symptoms worsen after 48 to 72 hours, the initial treatment is considered a failure, and veterinary consultation is necessary. Signs of treatment failure include a persistent high fever, a decline in body condition, or the onset of more severe respiratory distress. The veterinarian will evaluate the animal for a possible relapse or a lack of sensitivity to the initial antibiotic.
A change in the antibiotic protocol, known as retreatment, must be guided by the veterinarian. This decision is often made to target a different pathogen or to overcome potential antimicrobial resistance. Close monitoring and adherence to a clear retreatment plan are necessary to ensure the animal receives the most effective care and prevent the development of a chronic condition.