Bovine Respiratory Disease (BRD) is the most common disease in feeder cattle and one of the main causes of financial losses in cattle breeding. This disease encompasses various respiratory conditions like pneumonia, rhinitis, bronchitis and bovine pasteurellosis, among others.
Risk factors
Bovine Respiratory Disease is often triggered by situations that weaken the animal’s immune system, such as stress or infections. Predisposing factors are closely related to current production methods, especially fattening animals for meat:
Animal transport
During transport, factors like sharp temperature changes, dehydration, hunger, stress and fatigue can compromise the cattle’s immune response.
Commingling and crowding
Mixing cattle of different ages and immune levels in small spaces contributes to the spread of the disease.
Unfavorable environmental conditions
Extreme heat or cold, high humidity and poor ventilation increase the risk of BRD.
Abrupt changes in feed or deficient diet
Presence of viruses and/or parasites
These agents may affect the cattle’s immune response, making it less effective.
Predisposition of bovine species
The respiratory system of bovine livestock is naturally prone to this type of diseases, although some breeds may be more susceptible than others.
Main causes
Bovine respiratory disease can be caused by bacteria, viruses, parasites or even fungi, individually or in combination. These pathogens are spread directly from one animal to another through droplets suspended in the air or direct contact with contaminated surfaces. Nearly all the microorganisms involved in BRD depend on the respiratory system to survive.
Regardless of the specific trigger, it is important to note the role of Mannheimia haemolytica as the main cause of most cases. This type of bacteria is part of the normal microbiota in the upper respiratory tract of healthy ruminants. However, when conditions are right for it to proliferate, it can trigger an infection on its own. Another strain of bacteria commonly associated with these respiratory infections is Pasteurella multocida.
Signs and symptoms
Generally, the clinical signs of Bovine Respiratory Disease start between 7 and 10 days after a stressful situation, although it can be up to twice as long. In many cases, the disease is already quite advanced when the signs are detected, damaging the respiratory system and making the animal more susceptible to future infections.
The signs vary widely, from mild to severe, given the wide range of diseases BRD encompasses. Some of the most common symptoms include:
Financial losses
Respiratory issues are the main cause of financial losses in cattle farms, especially among calves within the first 10 months of birth. This disease is estimated to be responsible for 60% of all deaths in the first months of fattening.
In the United States, losses associated with this complex are estimated at approximately $1 billion per year, due to decreased yield. BRD morbidity oscillates between 10% and 50%, and mortality can be up to 40%.
In addition to direct losses due to fatal cases, the disease has a significant impact on average daily weight gain in calves, which can be 0.5 kg to 0.8 kg less. Feedlots are most impacted by BRD, although decreased milk yield in dairy cows also causes significant financial losses.
Financial Losses
How to fight bovine respiratory disease
Prevention
It is crucial to have a solid prevention strategy to minimize the animals’ exposure to respiratory pathogens in order to lower morbidity and mortality rates.
Diagnosis
Cattle tend to develop symptoms of the disease later than other species. So, it is crucial to be proactive in detecting the disease to control it and guarantee treatment is successful.
As the animals vary widely and come from different sources, it is almost obligatory to take a new sampling for each lot to understand the real situation of all the livestock.
If Bovine Respiratory Disease is suspected, samples should be taken from animals showing clinical signs to be analyzed in the lab. This will help identify the pathogens involved and choose the right treatment.
Treatment
As Bovine Respiratory Disease can be caused by various pathogens, it is crucial to identify the specific cause to choose the right, most effective treatment. Each additional treatment significantly increases costs: 40% more from the second treatment with antibiotics and 600% more from the third.
If it is a bacterial infection, the right antibiotic treatment must be administered. Susceptibility to antimicrobials must be monitored to properly manage treatment guidelines.
Inflammation and fever from the infection are the two biggest challenges of BRD. Administering antibiotics and NSAID (non-steroidal anti-inflammatory drugs) together has been proven more effective in curing and recovery of sick animals than administering these drugs separately.
In the most serious cases, symptomatic treatment is recommended in addition to antibiotics. This may include antipyretic to lower fever, expectorants or mucoactive agents to help eliminate secretions, and antitussives for dry cough, as it can spread the germs that cause BRD.
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