Respiratory Disease in Calves: Vaccination Strategies

Vaccination is key to protecting calves from respiratory diseases. Strategic vaccination programs, tailored to farm needs and guided by a veterinarian, help prevent illness, reduce economic losses, and improve calf health by building strong immunity against common viral and bacterial pathogens like BVDV, IBR, and Mannheimia haemolytica. Proper timing, vaccine selection, and management practices are crucial for success.

Calves, much like human children, are often vulnerable to sickness, and respiratory diseases pose a significant threat to their health and well-being. These illnesses, commonly grouped under the term Bovine Respiratory Disease (BRD), can make calves cough, struggle to breathe, and even lead to severe complications or death. For farmers and cattle producers, BRD translates into substantial economic losses due to treatment costs, reduced growth rates, and animal mortality. But there’s a powerful tool available to combat this challenge: strategic vaccination. This article will guide you through understanding calf respiratory diseases and developing effective vaccination strategies, helping you protect your herd and secure your investment. Let’s walk through the essential steps and insights to build a robust defense for your calves.

Understanding Respiratory Disease in Calves (BRD)

Bovine Respiratory Disease (BRD), often called “shipping fever,” is a complex illness affecting the lungs and airways of cattle. It’s not caused by a single agent but rather a combination of factors including stress, environmental conditions, and infections by various viruses and bacteria.

What is BRD? Causes and Impact

BRD is a multi-factorial disease. This means several things work together to make a calf sick.

The primary causes include:

Viruses: Common viral culprits include Bovine Viral Diarrhea Virus (BVDV), Infectious Bovine Rhinotracheitis (IBR), Parainfluenza-3 Virus (PI3), and Bovine Respiratory Syncytial Virus (BRSV). These viruses often weaken the calf’s immune system, making it easier for bacteria to invade.
Bacteria: Once viruses have compromised the respiratory tract, bacteria like Mannheimia haemolytica (formerly Pasteurella haemolytica), Pasteurella multocida, Histophilus somni, and Mycoplasma bovis can cause severe pneumonia.
Stress: Factors like weaning, transportation, commingling with new animals, changes in diet, extreme weather, and inadequate housing can suppress a calf’s immune system, making it more susceptible to infection.
Environment: Poor ventilation, dusty conditions, high humidity, and overcrowding contribute to the spread of pathogens and stress on the calves.

The impact of BRD is significant:

Economic Losses: These include direct costs for veterinary care, antibiotics, and other treatments. Indirect costs involve reduced weight gain, lower feed efficiency, increased labor, and potential death losses.
Reduced Performance: Calves that recover from BRD often experience “chronic” effects, meaning they don’t grow as well, may have permanent lung damage, and might not reach their full genetic potential.
Animal Welfare: BRD causes significant discomfort and pain for the affected calves, raising animal welfare concerns.

Why Are Calves So Susceptible?

Calves are particularly vulnerable to BRD for several reasons related to their developing immune systems and common management practices:

Immature Immune System: Newborn calves rely heavily on antibodies received from their mother’s first milk (colostrum). If colostrum intake is insufficient or of poor quality, their immune protection is weak. Even with good colostrum, this passive immunity wanes over time, leaving a “window of susceptibility” before the calf’s own active immune system fully develops.
Stressors: Calves often face multiple stressors early in life. Weaning is a major stressor, as it involves dietary changes, separation from the mother, and often mixing with new calves. Transportation to sale barns or new farms further compounds this stress.
Commingling: Bringing calves from different sources together, especially at sale barns, exposes them to a wide variety of pathogens that they may not have encountered before, overwhelming their immune systems.
Environmental Challenges: Young calves are more sensitive to changes in temperature, humidity, and air quality. Poor ventilation in calf housing can lead to a buildup of ammonia and other irritants, damaging the respiratory tract and making it easier for pathogens to infect.

Understanding these vulnerabilities is the first step in developing an effective BRD prevention strategy, with vaccination playing a central role.

The Importance of Vaccination in BRD Prevention

Vaccination is a cornerstone of any comprehensive BRD prevention program. It works by preparing the calf’s immune system to fight off specific pathogens before they cause disease.

Why Vaccinate? Prevention and Economic Benefits

Vaccination offers numerous advantages:

Disease Prevention: The primary goal of vaccination is to prevent clinical disease or reduce its severity. By exposing the calf’s immune system to weakened or inactive forms of pathogens, vaccines stimulate the production of antibodies and memory cells. If the calf later encounters the actual pathogen, its immune system can mount a rapid and effective defense.
Reduced Treatment Costs: Preventing disease means fewer sick calves, which directly translates to lower veterinary bills, less money spent on antibiotics, and reduced labor for treating sick animals.
Improved Performance: Healthy calves grow faster, convert feed more efficiently, and reach market weight sooner. Preventing BRD helps maintain growth rates and avoids the long-term performance setbacks associated with chronic lung damage.
Reduced Mortality: Severe cases of BRD can be fatal. Vaccination significantly lowers the risk of death due to respiratory illness.
Enhanced Animal Welfare: By preventing illness, vaccination improves the overall health and comfort of the calves, aligning with good animal welfare practices.
Reduced Antibiotic Use: A strong vaccination program can decrease the need for antibiotics, which is important for managing antibiotic resistance and meeting consumer demands for responsible livestock production.

Vaccine Types: Modified-Live (MLV) vs. Killed Vaccines

Understanding the different types of vaccines is crucial for selecting the right product for your herd:

Modified-Live Vaccines (MLV):
- How they work: Contain live, but weakened (attenuated), versions of the virus or bacteria. They replicate within the calf’s cells, mimicking a natural infection without causing severe disease.
- Advantages: Typically provide a stronger, longer-lasting immune response with fewer doses (often a single dose followed by a booster is sufficient). They stimulate both humoral (antibody) and cell-mediated immunity.
- Disadvantages: Require careful handling and storage (refrigeration, avoid direct sunlight). Cannot be used in pregnant animals unless specifically labeled as safe for pregnant animals or nursing calves (due to potential for abortion or congenital defects in some cases). Can cause mild vaccine reactions.
- Common use: Widely used in calves and non-pregnant adults.
Killed Vaccines:
- How they work: Contain inactivated (killed) versions of the virus or bacteria. They cannot replicate in the animal.
- Advantages: Generally safer for pregnant animals and calves with compromised immune systems. More stable in storage. No risk of shedding live organisms.
- Disadvantages: Often require multiple doses (initial series and boosters) to achieve adequate immunity. May provide a less robust or shorter-lived immune response compared to MLVs. Primarily stimulate humoral (antibody) immunity.
- Common use: Used when MLVs are contraindicated, such as in pregnant cows or very young, stressed calves.

The choice between MLV and killed vaccines depends on the specific pathogens targeted, the age and physiological status of the calves, and the overall herd health program. Consulting with a veterinarian is essential for making these decisions.

Key Pathogens Targeted by Vaccines

Effective BRD vaccination strategies target the most common viral and bacterial pathogens that cause respiratory disease in calves.

Viral Pathogens

Vaccines are available for the following key viruses:

Bovine Viral Diarrhea Virus (BVDV):
- Impact: Causes immunosuppression, making calves more susceptible to other infections. Can cause respiratory disease directly, but its main role is weakening the immune system. Also responsible for reproductive issues and persistently infected (PI) animals.
- Vaccine type: Both MLV and killed vaccines are available. MLVs are generally preferred for their robust immune response, but killed vaccines are used in breeding herds or when MLVs are contraindicated.
Infectious Bovine Rhinotracheitis (IBR):
- Impact: Causes “red nose” disease, leading to severe upper respiratory tract inflammation, fever, and sometimes pneumonia. Can also cause abortion in pregnant cows.
- Vaccine type: Both MLV and killed vaccines. MLVs are highly effective, but specific MLV strains are approved for use in pregnant cows.
Parainfluenza-3 Virus (PI3):
- Impact: Causes mild respiratory signs, but its main role is to damage the respiratory tract lining, making it easier for bacteria to invade.
- Vaccine type: Usually included in combination vaccines (MLV or killed).
Bovine Respiratory Syncytial Virus (BRSV):
- Impact: Can cause severe pneumonia, especially in young calves, leading to difficulty breathing and high mortality rates.
- Vaccine type: Both MLV and killed vaccines are available, often in combination products.

Bacterial Pathogens

Vaccines target these common bacterial contributors to BRD:

Mannheimia haemolytica (formerly Pasteurella haemolytica):
- Impact: The most common bacterial cause of severe, acute pneumonia in calves, often leading to rapid onset of illness and high mortality. It produces toxins that damage lung tissue.
- Vaccine type: Killed bacterial vaccines (bacterins) or toxoid vaccines (targeting the toxins produced by the bacteria). Often combined with viral vaccines.
Pasteurella multocida:
- Impact: Another significant bacterial cause of pneumonia, often found in combination with Mannheimia haemolytica.
- Vaccine type: Killed bacterins, often combined with Mannheimia haemolytica vaccines.
Histophilus somni:
- Impact: Can cause respiratory disease, but also other conditions like thrombotic meningoencephalitis (TEME), arthritis, and myocarditis.
- Vaccine type: Killed bacterins.
Mycoplasma bovis:
- Impact: Causes chronic pneumonia, often resistant to standard antibiotic treatments. Can also cause arthritis and ear infections.
- Vaccine type: Killed bacterins are available, but their efficacy can be variable. Management practices are often more critical for controlling Mycoplasma.

Many vaccines are “combination” products, meaning they contain antigens for several of these viruses and bacteria in a single dose, simplifying administration and ensuring broad protection.

Developing a Strategic Vaccination Program

A successful vaccination program is not a one-size-fits-all solution. It must be tailored to the specific farm, management practices, and disease risks.

Consulting a Veterinarian: The Crucial First Step

This cannot be stressed enough. A local veterinarian is your best resource for developing a customized vaccination plan. They can:

Assess Risk Factors: Evaluate your farm’s specific challenges, such as herd size, calf source (closed herd vs. purchased calves), housing, nutrition, and history of BRD outbreaks.
Identify Local Pathogens: Determine which specific viruses and bacteria are prevalent in your area or have affected your herd in the past. This might involve diagnostic testing of sick or deceased calves.
Select Appropriate Vaccines: Recommend the most effective MLV or killed vaccines, combination products, and specific brands based on your risk assessment.
Develop a Schedule: Create a vaccination timeline that accounts for maternal antibody interference, calf age, weaning, and other management events.
Provide Training: Offer guidance on proper vaccine handling, administration techniques, and record-keeping.
Monitor Efficacy: Help evaluate the success of the vaccination program and make adjustments as needed.

Timing of Vaccination

Timing is critical to maximize vaccine effectiveness:

Pre-weaning (Calves on Cow):
- Goal: Provide initial protection before the major stress of weaning.
- Considerations: Maternal antibodies can interfere with MLV vaccines in very young calves. Often, a killed vaccine or an intranasal MLV (which bypasses maternal antibodies) is given first, followed by a booster. Some MLVs are labeled for use in calves as young as 30 days of age.
- Typical timing: 2-4 weeks before weaning.
Weaning:
- Goal: Boost immunity during a high-stress period.
- Considerations: Calves are highly stressed at weaning, which can temporarily suppress their immune response. Vaccines should ideally be given 2-3 weeks before weaning to allow immunity to develop, or a booster given at weaning if the initial dose was given earlier.
Pre-shipping/Pre-conditioning:
- Goal: Prepare calves for the stress of transportation and commingling.
- Considerations: Calves should ideally receive their full vaccination series (initial dose plus booster) at least 2-3 weeks before shipping to ensure robust immunity. This is especially important for calves entering feedlots or backgrounding operations.

Maternal Antibody Interference

Maternal antibodies, received through colostrum, protect young calves but can also neutralize live vaccines, preventing the calf from developing its own active immunity. This “window of susceptibility” varies, but generally, maternal antibodies decline around 3-5 months of age. Your veterinarian will help design a schedule that accounts for this, often involving an initial vaccine dose that may be partially interfered with, followed by a booster after maternal antibodies have waned, or using intranasal vaccines that can overcome some interference.

Booster Shots

Most injectable vaccines, especially killed vaccines, require a booster dose 2-4 weeks after the initial vaccination to elicit a strong and long-lasting immune response. Missing the booster shot significantly reduces the effectiveness of the vaccination program. Intranasal vaccines often provide a strong initial response and may not require a booster.

Vaccine Administration: Route and Handling

Proper administration is as important as vaccine selection:

Route of Administration:
- Subcutaneous (SQ): Injected under the skin. Common for many vaccines.
- Intramuscular (IM): Injected into the muscle. Some vaccines require this.
- Intranasal (IN): Administered into the nostrils. These vaccines stimulate local immunity in the respiratory tract very quickly and can be effective even in the presence of maternal antibodies. They often provide faster protection.
Proper Handling:
- Storage: Always store vaccines according to manufacturer instructions, typically refrigerated (35-45°F or 2-7°C). Protect from freezing and direct sunlight.
- Mixing: Mix MLV vaccines immediately before use and use them within the recommended time frame (usually 1 hour) as the live organisms degrade quickly.
- Cleanliness: Use clean needles and syringes. Change needles frequently (e.g., every 10-15 calves or if bent/dirty) to prevent contamination and reduce pain.
- Dosage: Administer the full, correct dose as per the label.
- Site: Follow label instructions for injection site (e.g., neck region for SQ injections to preserve meat quality).

Here’s an example of a common calf vaccination schedule, which should always be customized with a veterinarian:

Table 1: Common Calf Vaccination Schedule Example

Calf Age/Stage	Vaccine Type (Examples)	Route	Notes
Birth to 1 Month	Intranasal IBR, PI3, BRSV	Intranasal	Provides rapid local immunity, effective in presence of maternal antibodies. May be used as early as 3 days old.
1-3 Months	Killed BVDV, IBR, PI3, BRSV, Mannheimia haemolytica	SQ	Used when MLVs are not suitable or as a first dose. Requires booster.
Pre-weaning (4-6 weeks before)	MLV IBR, BVDV, PI3, BRSV, +/- Mannheimia haemolytica	SQ	Allows immunity to develop before weaning stress. Check label for age restrictions.
Weaning / Pre-conditioning (2-3 weeks before shipping)	Booster: MLV IBR, BVDV, PI3, BRSV, Mannheimia haemolytica, Pasteurella multocida, Histophilus somni	SQ	Crucial booster for strong, lasting immunity. Consider clostridial vaccines too.
Arrival at Feedlot/Backgrounder	If unknown history: Intranasal IBR, PI3, BRSV; Injectable MLV or Killed combo BRD vaccine + Mannheimia haemolytica	IN / SQ	May need to revaccinate if history is unknown or previous vaccinations were incomplete/poorly timed.

Disclaimer: This table is a general example. Always consult your veterinarian for a specific vaccination protocol tailored to your herd’s needs and local disease prevalence.

Beyond Vaccination: Holistic BRD Management

While vaccination is critical, it’s only one part of a comprehensive BRD prevention strategy. Effective management practices significantly reduce stress and exposure, allowing vaccines to work more effectively.

Colostrum Management

The single most important factor for calf health in the first few weeks of life is adequate colostrum intake. Colostrum provides passive immunity (maternal antibodies) that protects the calf until its own immune system can fully develop.

Quality: Ensure cows receive proper nutrition before calving to produce high-quality colostrum.
Quantity: Calves should receive 10-15% of their body weight in colostrum within the first 6-12 hours of life. For example, a 90-pound calf needs 9-13.5 pounds (about 1-1.5 gallons) of colostrum.
Timeliness: The calf’s ability to absorb antibodies decreases rapidly after birth. The sooner, the better.

Nutrition

Proper nutrition for both the dam and the calf is vital for a strong immune system.

Dam Nutrition: Well-nourished cows produce healthier calves and better-quality colostrum.
Calf Nutrition: Provide a balanced diet with adequate energy, protein, vitamins (especially A, D, E), and minerals (especially copper, selenium, zinc). Good nutrition supports immune function and overall growth.

Environmental Control (Ventilation, Housing)

The calf’s environment plays a huge role in disease prevention.

Ventilation: Good airflow removes airborne pathogens, dust, and noxious gases (like ammonia) that irritate the respiratory tract. Avoid drafts directly on calves while ensuring fresh air.
Housing: Provide clean, dry, and well-bedded housing. Individual calf hutches or well-managed group pens reduce pathogen transmission. Ensure adequate space per calf to prevent overcrowding.
Temperature Regulation: Protect calves from extreme temperatures. Young calves are particularly susceptible to cold stress.

Stress Reduction (Weaning, Transport)

Minimizing stress is crucial because stress suppresses the immune system.

Weaning: Implement “fenceline weaning” (calves separated from dams but still able to see and touch across a fence) or “two-stage weaning” (using nose flaps) to reduce the stress of separation. Wean calves gradually.
Transportation: Ensure clean, well-ventilated trailers. Avoid overcrowding. Minimize travel time. Provide water and rest stops for long journeys.
Commingling: If purchasing calves, try to source from as few places as possible. Isolate new arrivals for a period (e.g., 2-3 weeks) to observe for illness and allow them to acclimate.

Biosecurity

Preventing the introduction and spread of disease-causing agents.

Quarantine: Isolate new animals for at least 3-4 weeks. During this time, monitor for signs of illness, vaccinate, and deworm.
Hygiene: Regularly clean and disinfect calf housing, feeding equipment, and water troughs.
Traffic Control: Limit access for visitors and vehicles that might carry pathogens onto the farm.

Early Detection and Treatment

Even with the best prevention, some calves may still get sick.

Daily Monitoring: Regularly observe calves for early signs of illness (e.g., dullness, reduced appetite, nasal discharge, coughing, rapid breathing, droopy ears).
Prompt Treatment: Isolate sick calves immediately and administer appropriate treatment as prescribed by your veterinarian. Early intervention improves recovery rates and reduces disease spread.

For more insights into animal health, you might find this article helpful: Dog Vaccines & Boosters: How Often Does Your Dog Need Shots?

Common Vaccination Challenges and Solutions

Even with a well-planned vaccination program, challenges can arise. Understanding these and knowing how to address them is key to success.

Vaccine Failure: Causes and Troubleshooting

Vaccine failure occurs when a vaccinated animal still gets sick. This is rarely due to a faulty vaccine itself but rather issues with its handling, administration, or the animal’s response.

Common causes of vaccine failure include:

Improper Handling/Storage: Vaccines are sensitive. Exposure to heat, cold (freezing), or direct sunlight can kill live organisms in MLVs or degrade antigens in killed vaccines.
Incorrect Administration:
- Wrong route: Giving an SQ vaccine IM, or vice versa.
- Wrong dose: Under-dosing or over-dosing.
- Dirty equipment: Using dirty needles or syringes can introduce bacteria or inactivate the vaccine.
- Expired vaccine: Using vaccines past their expiration date.
Maternal Antibody Interference: As discussed, passive immunity can neutralize MLV vaccines in young calves, preventing active immunity development.
Immunosuppression: Calves that are already stressed (e.g., from weaning, transport, poor nutrition, or concurrent illness) may have a suppressed immune system and cannot mount an effective response to the vaccine.
Timing Issues:
- Too early: Vaccinating before the calf’s immune system is mature enough.
- Too late: Vaccinating after exposure to the pathogen has already occurred.
- No booster: Failing to give the required booster shot for killed vaccines or some MLVs.
New or Different Pathogen Strains: The vaccine may not cover the specific strain of virus or bacteria circulating in the herd.
Poor Nutrition: Malnourished calves cannot mount a strong immune response.
Chronic Disease: Calves with underlying chronic conditions may not respond well to vaccines.

Troubleshooting Vaccine Failure:

Review Protocols: Carefully review your vaccine handling, storage, and administration procedures.
Consult Veterinarian: Work with your vet to re-evaluate your vaccination schedule, vaccine choices, and overall herd health plan. They may recommend diagnostic testing to identify the specific pathogens involved.
Address Stressors: Implement strategies to reduce stress (weaning, transport, commingling).
Improve Nutrition: Ensure calves are receiving adequate nutrition.
Post-Mortem Exams: If calves are dying, a necropsy by a diagnostic lab can provide crucial information on the exact cause of death and the pathogens involved.

Cost-Benefit Analysis of Vaccination

While vaccines represent an upfront cost, the long-term benefits typically far outweigh them.

Costs: Include the price of vaccines, needles, syringes, labor for administration, and veterinary consultation fees.
Benefits: Reduced treatment costs (antibiotics, anti-inflammatories, veterinary visits), decreased mortality, improved growth rates, better feed conversion, and higher market value for healthier calves.

A simple calculation can illustrate the value: If vaccinating a calf costs $5-10 but prevents a BRD case that would cost $50-100 in treatment and lost performance, the return on investment is clear. Furthermore, the improved welfare of the animals is an intangible but significant benefit.

Latest Advancements in BRD Vaccination

Research and development in veterinary medicine are constantly bringing new tools to the fight against BRD.

Newer Vaccines and Technologies

Vaccine technology continues to evolve:

Intranasal Vaccines: While not entirely new, more intranasal options are becoming available, offering rapid onset of immunity and the ability to bypass maternal antibody interference, making them ideal for young calves or at-risk calves upon arrival.
Adjuvants: Newer adjuvants (substances added to vaccines to enhance the immune response) are being developed to create stronger, longer-lasting immunity with fewer side effects.
Subunit Vaccines: These vaccines use only specific parts of the pathogen (e.g., a protein) to stimulate immunity, rather than the whole organism. They can be very safe but may require more sophisticated delivery systems.
Autogenous Vaccines: In some cases, if a specific, unusual pathogen is causing persistent problems on a farm, a custom vaccine can be made from isolates collected directly from the affected animals on that farm. These are highly specific but require diagnostic work.

Research Directions

Future research aims to develop even more effective and user-friendly vaccines:

Broader Spectrum Vaccines: Vaccines that protect against a wider range of strains or even multiple pathogens simultaneously.
Improved Efficacy Against Mycoplasma bovis: This pathogen remains a significant challenge, and more effective vaccines are needed.
Genetic Approaches: Research into using genetic engineering to create novel vaccine platforms that are highly effective and safe.
Better Delivery Systems: Exploring methods for easier and less stressful vaccine administration, such as edible vaccines or patch-based delivery.
Understanding Immunity: Deeper research into the nuances of the calf immune system will help design vaccines that elicit the most robust and appropriate immune responses.

Here’s a summary table of common respiratory pathogens and the general types of vaccines available:

Table 2: Key Respiratory Pathogens and Their Vaccine Types

Pathogen	Type (Virus/Bacteria)	Common Vaccine Types	Notes
Bovine Viral Diarrhea Virus (BVDV)	Virus	Modified-Live (MLV), Killed	MLVs offer strong immunity; Killed for pregnant animals or when MLV is contraindicated.
Infectious Bovine Rhinotracheitis (IBR)	Virus	Modified-Live (MLV), Killed, Intranasal	MLVs are highly effective; Intranasal provides rapid local immunity.
Parainfluenza-3 Virus (PI3)	Virus	Modified-Live (MLV), Killed, Intranasal	Often included in combination vaccines.
Bovine Respiratory Syncytial Virus (BRSV)	Virus	Modified-Live (MLV), Killed, Intranasal	Important for young calves; often in combination vaccines.
Mannheimia haemolytica	Bacteria	Bacterin (Killed), Toxoid	Crucial for bacterial pneumonia prevention. Often combined with viral vaccines.
Pasteurella multocida	Bacteria	Bacterin (Killed)	Often combined with Mannheimia haemolytica vaccines.
Histophilus somni	Bacteria	Bacterin (Killed)	Included in some BRD vaccine combinations.
Mycoplasma bovis	Bacteria	Bacterin (Killed)	Efficacy can be variable; management is key.

Conclusion

Respiratory disease in calves remains a formidable challenge for cattle producers worldwide. However, with a strategic and well-executed vaccination program, coupled with robust management practices, the impact of BRD can be significantly mitigated. Understanding the various pathogens, vaccine types, and the critical importance of timing and proper administration empowers producers to make informed decisions.

Remember, vaccination is not a standalone solution but a vital component of a holistic approach to calf health. Prioritizing colostrum intake, providing optimal nutrition, ensuring good environmental conditions, minimizing stress, and implementing strict biosecurity measures all work in concert with vaccination to build resilient, healthy calves.

The most crucial step in developing an effective vaccination strategy is to partner with your veterinarian. They possess the expertise to assess your specific farm’s risks, identify prevalent pathogens, and tailor a vaccination schedule that maximizes protection for your herd. By investing in proactive health management, you not only protect your calves from debilitating diseases but also safeguard your economic future and uphold the highest standards of animal welfare.

Frequently Asked Questions (FAQ)

Q1: What is BRD in calves?

A1: BRD stands for Bovine Respiratory Disease, also known as “shipping fever.” It’s a common and complex illness affecting the lungs and airways of calves, caused by a combination of stress, environmental factors, and infections from various viruses (like BVDV, IBR) and bacteria (like Mannheimia haemolytica).

Q2: Why is it important to vaccinate calves against respiratory diseases?

A2: Vaccinating calves helps prevent them from getting sick or reduces the severity of illness. This leads to fewer treatment costs, better growth rates, reduced mortality, and improved overall animal welfare. Vaccines prepare the calf’s immune system to fight off pathogens before they cause disease.

Q3: What’s the difference between Modified-Live (MLV) and Killed vaccines?

A3: Modified-Live Vaccines (MLVs) contain weakened, live versions of pathogens that replicate in the calf, mimicking a natural infection and providing strong, long-lasting immunity. Killed vaccines contain inactivated pathogens; they are safer for pregnant animals but often require more doses for effective immunity. Your veterinarian will recommend the best type for your situation.

Q4: When is the best time to vaccinate calves?

A4: The best timing depends on your management system and the calf’s age. Often, calves receive initial vaccinations a few weeks before weaning (to build immunity before stress) and then a booster shot at weaning or before shipping. Very young calves might receive intranasal vaccines. Always consult your veterinarian for a specific schedule.

Q5: Can calves still get sick after being vaccinated?

A5: Yes, vaccination reduces the risk of illness, but it’s not a 100% guarantee. “Vaccine failure” can occur due to improper vaccine handling, incorrect administration, severe stress on the calf, overwhelming exposure to pathogens, or if the calf’s immune system is already compromised. Vaccination works best as part of a comprehensive health management plan.

Q6: What other things can I do to prevent BRD besides vaccination?

A6: Beyond vaccination, focus on holistic management. Ensure calves receive enough high-quality colostrum at birth, provide excellent nutrition, maintain clean and well-ventilated housing, reduce stress during weaning and transport, and implement strong biosecurity measures to prevent disease introduction. Early detection and prompt treatment of sick calves are also vital.

Q7: How often do calves need booster shots?

A7: Most injectable vaccines, especially killed vaccines, require a booster dose 2-4 weeks after the initial vaccination to ensure strong, lasting immunity. Intranasal vaccines often do not require a booster. Always follow the specific instructions on the vaccine label and your veterinarian’s recommendations.