Summer pneumonia, sometimes referred to as pasture pneumonia, tends to develop late in the season for producers. It usually hits calves that are still on pasture and haven’t been weaned yet—typically between one and five months old. The frustrating part? It often affects calves that look perfectly healthy one day and are sick the next.
So, why does this happen? That’s the question that’s had ranchers scratching their heads for years. Respiratory disease in young calves is always a concern, but summer pneumonia feels especially unpredictable. Some years, you never see it. In other years, it appears without warning—and it’s tough to catch early.
Part of the challenge is that summer pneumonia isn’t fully understood. It doesn’t always follow the rules. It can show up in well-managed herds just as easily as in herds dealing with stress, drought, or nutritional issues. And because symptoms can be subtle, it’s easy to miss until calves are really struggling.
Even if your calves aren’t what you’d consider “high risk,” learning to spot summer pneumonia—and understanding what might trigger it—is a big step in the right direction. Knowing what to watch for helps you take action early, which can result in a faster recovery, fewer losses, and less stress on both you and your calves.
Bottom line: Summer pneumonia may be unpredictable, but that doesn’t mean you’re powerless. A little awareness goes a long way in protecting your herd.
What Is Summer Pneumonia—And Why Does It Sneak Up on You?
Summer pneumonia is a bit of a head-scratcher. It’s a respiratory disease that shows up in pre-weaned calves still out on pasture—often when you least expect it. What makes it especially frustrating is that it doesn’t just strike herds that are under stress or poorly managed. Even well-cared-for calves can come down with it, which makes tracking down a single cause feel like chasing smoke.
While we don’t have all the answers, we do know a few things. For starters, the bugs behind summer pneumonia aren’t new. They’re the same ones that cause respiratory disease after weaning—think Mannheimia haemolytica, Pasteurella multocida, Haemophilus somni, Infectious Bovine Rhinotracheitis (IBR), and Bovine Respiratory Syncytial Virus (BRSV). The difference is in how and when they strike.
With summer pneumonia, symptoms can sneak up on you under the radar. You might not see the classic signs you’d expect, such as heavy breathing or coughing. Instead, calves may look a little sluggish, hang back from the herd, or act a bit “off.” That’s why early detection is so crucial. Being vigilant and spotting these subtle signs early can give you a head start in managing the disease.
Because the symptoms are subtle, it’s easy to miss them until they become more serious. That’s why having a solid health plan in place—including good nutrition, proper colostrum intake, and timely vaccinations—is so important. These measures can make a significant difference in preventing and managing summer pneumonia, giving you peace of mind and keeping your herd healthy.
Bottom line? While summer pneumonia can feel random, being informed is your best defense. Watching for the quiet signs and having a prevention plan in place can go a long way toward keeping your calves healthy through the summer months. Your knowledge and vigilance can make a significant difference in the health of your herd.
How to Spot It Early: Symptoms to Watch For
One of the trickiest things about summer pneumonia is how quietly it can sneak up on your calves. Unlike other respiratory diseases, it doesn’t always present with obvious red flags, such as coughing or
rapid breathing—especially when calves are just grazing in the pasture. Those signs may only appear if the herd is moved or stressed.
Instead, the early signs are subtle. You might notice a calf that’s just not acting like the rest. They may be moving more slowly, hanging back, or struggling to keep up with the herd. That sluggish behavior is often one of the first clues. Other signs to watch for include:
- Droopy ears
- A mild fever
- Calves separating from the group or lagging behind
Basically, if a calf looks a little “off,” trust your gut and keep an eye on them.
Part of the challenge with understanding summer pneumonia is that it doesn’t often lead to high death losses. While that’s obviously a good thing, it also means we don’t get many post-mortem cases to study. Therefore, much of what we know is derived from trial, error, and observation.
Veterinarians will usually take nasal swabs to try to pinpoint the cause of the illness, but here’s the catch: what’s living in the nose doesn’t always match what’s happening deep in the lungs. That’s why spotting those early, subtle symptoms—and acting quickly—can make all the difference.
What Triggers It? Conditions That Raise the Risk
While a specific cause of summer pneumonia has yet to be found, several factors have been shown to contribute to its occurrence. These include poor colostrum quality or quantity, exposure to older calves that may be carriers of various viruses, hot, dry, and dusty conditions that can compromise the respiratory tract’s defense mechanisms, and wide temperature swings between day and night, which can stress the calves’ immune system. It’s essential to note that these factors alone should not be used as a basis for diagnosis. Consulting a veterinarian is always recommended, as they can provide professional advice and help you develop a comprehensive health plan for your herd.
Colostrum’s Role: Why It Still Matters Months Later
When herds were diagnosed with summer pneumonia, two patterns emerged. According to the University of Nebraska, one of these is a very young calf (less than a month of age). The others are calves that reach 90-120 days of age. As you may have guessed, colostrum plays a part in these factors.
For younger calves, the risk of summer pneumonia is believed to be due to the poor quality or quantity of colostrum. The dam’s poor nutrition contributes to the poor state of colostrum before calving, often exacerbated by factors such as drought. It’s essential to ensure that calves receive high-quality colostrum within the first few hours of birth, as it provides necessary antibodies and nutrients that can help prevent respiratory diseases, such as summer pneumonia. Suppose you need to give a colostrum replacer. In that case, I talk about what to consider in a previous post, ‘5 astonishing truths about colostrum to start calves right’.
When it comes to older calves, the effectiveness of the colostrum is a crucial factor. As calves age, the protection from colostrum begins to decline. Four-month-olds or older are in the sickness sweet spot. They are too old for the colostrum to be of any use, and they are too young to have developed their own immunity to viruses. This situation underscores the importance of ensuring that calves receive high-quality colostrum within the first few hours of life. Helping their immunity is having the correct vaccination program in place.
Vaccines: When and What to Give
Many calves get their first respiratory vaccine when they are very young. The age at which they get their vaccines will play a role in their effectiveness. Really young calves, such as those two months of age, will not have as good a response as those that are seven to eight months of age. Of course, though it may not be as effective, vaccines at any age are better than no vaccines at all.
The type of vaccine you use also plays a role in its effectiveness. Visiting your veterinarian or a local feed store will reveal that not all vaccines are identical. You can choose from various types, including viruses or bacteria, as well as modified live or killed. It is essential to visit your veterinarian to determine which vaccines are suitable for you and your operation.
Other Stressors That Tip the Scale
When it comes to summer pneumonia, it’s rarely just one thing causing trouble. Several outside factors can tip the odds against your calves, even when you’re doing everything right.
One significant contributor is exposure to older calves. These older calves may appear perfectly healthy, but they can still carry viruses to which younger calves haven’t yet developed immunity. So when the young ones are turned out with them, it’s like sending a rookie into a locker room full of seasoned players—germs can spread quickly, even if no one’s visibly sick.
Weather also plays a huge role. Think about those hot, dry, dusty summer days. That dust doesn’t just make you cough—it can wear down a calf’s natural defenses in its respiratory tract, making it easier for bacteria and viruses to take hold. Add in some wide temperature swings—like hot afternoons followed by cool nights—and you’ve got a perfect storm for stressing the immune system.
Then there’s the stress factor. Any time you crowd calves or separate them from their moms—like during breeding—it adds pressure to an already delicate situation. Stress lowers immunity, and when combined with the other factors, it creates an environment where summer pneumonia can take hold.
Even though these things might seem small on their own, together, they can have a significant impact. That’s why paying attention to environmental stressors, managing herd movement, and reducing exposure risks can help you stay ahead of the game when it comes to protecting your calves.
Treatment: What Works—and What Gets in the Way
When it comes to treating calves with summer pneumonia, several options are available. Certain antibiotics, such as oxytetracycline or florfenicol, have shown reasonable recovery rates. Additionally, anti-inflammatory medicines like flunixin meglumine can help reduce fever and inflammation. It’s essential to note that these treatments are often highly effective, providing a sense of confidence in their efficacy.
The primary challenge in treating calves with summer pneumonia is that it can be difficult to administer treatments to individual calves when they are grazing in the pasture. It can be challenging to identify which ones are sick, and it is even hard to approach the calf in the field to administer the medicine. If a large portion of the herd is affected, pre-weaning vaccinations and antibiotics can be given to the calves. This result underscores the importance of early detection and a proactive approach to herd health management.
Can Vaccines Prevent It? Yes—But Not Always
Producers must use vaccines against respiratory viruses at branding and turn out to try to reduce the risk of summer pneumonia. A word of caution, though: Summer pneumonia can still happen even in a well-vaccinated herd.
Fortunately, vaccines that possess IBRV, BRSV, Parainfluenza-3, and Bovine Viral Diarrhea Virus are readily available. They come in both killed and modified-live versions, offering a variety of options to suit your herd’s needs and giving you a sense of security in disease prevention.
When it comes to young calves, intranasal vaccines are a trendy choice. They are believed to offer good local immunity and stimulate excellent overall immunity in the nasal passages. If these are a good option, they are something to discuss with your veterinarian.
