When calves die in their first three weeks of life, the major causes are calving-related problems or weather-related causes (25.7% and 25.6%, respectively), according to the National Animal Health Monitoring System (NAHMS) Beef 2007–2008 report.

But after 3 weeks of age, almost one-third of beef calf deaths are from respiratory disease. W. Mark Hilton, DVM, Dipl. ABVP-Beef Cattle, Purdue University, generally sees respiratory issues and summer pneumonia in calves between 2–4 months of age.

Why calves get sick

“It seems when we see a significant number of summer pneumonia cases, there are multiple risk factors present,” Hilton explains. “I have never found a herd where there is one glaring problem and we fix it and the disease
goes away.”

There is no doubt that poor colostral transfer is a risk factor. Hilton notes that studies put failure of passive transfer (FPT) in beef at 20–30%. “That surprises many people,” he says. “Louis Perino’s work showed a 5–4 times greater preweaning morbidity in calves with FPT.” High pathogen load is surely a risk factor as is immunity.

A variety of pathogens can be at play, and Hilton says previously he has cultured Pasteurella multocida from the majority of cases. “We suspect a viral agent would also be involved in most cases,” he adds.

Listlessness and depression are some of the first clinical signs of summer pneumonia in calves, and Hilton says a cow with a full udder bellowing for her calf can also give you an indication of a problem. He says treatment is usually quite successful if calves are found in the first 24 hours of the disease. “I have used numerous approved antibiotics with good success,” he says.

Prevention: vaccination

Hilton suggests vaccinating the cows prebreeding and again six weeks precalving with a modified-live (MLV) IBR-BVD-PI3 vaccine labeled for use on pregnant cows. In subsequent years, he says you could just vaccinate the cows precalving.

He also suggests using an MLV IBR-BVD-PI3-BRSV vaccine on the calves when the youngest calf is 7 days of age. The NAHMS Beef 2007–2008 report indicates that 69.1% of calves were vaccinated against respiratory disease across all operations. One half of calves on operations with 200 or more cows were vaccinated against respiratory disease two times compared with 16.8% of calves on operations with one to 49 cows.

“Older work says you cannot vaccinate young calves as maternal immunity will block the vaccine,” he says. “We know that is not true for some of the viral pathogens.”

Prevention: cow and calf management

Hilton offers these management practices that can help prevent respiratory and other diseases in the young beef calf:

  • High-quality and quantity of colostrum. Hilton tells clients, “If in doubt, milk her out” and give it to the calf. “We use the term ‘2 x 6 and 4 x 12’ to mean ‘make sure the calf gets two quarts by four hours and four quarts by 12 hours of age’,” he explains. A trick he uses with calves where he is unsure if it nursed is to give the cow 1cc oxytocin and milk out the colostrum. Tube the calf with two quarts and then separate the calf from the cow with a small gate (so cow can still sniff/lick calf) for eight hours. “Turn the calf with the cow and if he nurses, you are home free. If not, you have a ‘dumb’ calf that will have to be tube fed for some time.”
  • Ensure proper nutrition of the dam. Hilton says body condition score (BCS) is another way to help ensure good colostrum and milk production. He suggests cows have a BCS of 5–6 at calving and heifers in BCS 6–7 on a 9-point scale. While a thin cow will still produce colostrum and milk for the calf, it may take her four to five months to come into heat and subsequent fertility can be severely compromised.
  • Decrease dystocia. Use genetic selection to minimize calving problems. Calves born unassisted stand and nurse sooner and therefore have a better chance of ingesting an adequate volume of colostrum in a timely manner.
  • Increase calf vigor at birth with improved heterosis. Calves with increased heterosis are quicker to nurse and also ingest more colostrum.
  • Decrease cold weather stress. If you calve at a time of the year that calves have to be born inside you are increasing the chance of having neonatal disease. Calve at a time of year where calves have a better chance to thrive.
  • Boost immunity to specific diseases. Be sure cows are on an appropriate vaccination program.
  • Reduce pathogen load. Reduce the chance of introduction or carryover of disease organisms by at least using the concept of the Sandhills calving system (www.unl.edu, search “Sandhills Calving System”).
  • Don’t buy disease. Hilton says to never buy a calf for a cow that lost her calf and never buy cow-calf pairs during calving seasons. “I have seen disasters with both events.”
  • Minimize the chance of spreading disease. First-calf heifers do not have the breadth of immunity as compared to mature cows, so don’t calve heifers and adult cows in the same area.

The cost of summer pneumonia

Aside from morbidity and mortality, additional costs of calf respiratory disease include the increased labor at a time when cows and calves should be very low maintenance. Fortunately, Hilton has not seen a high level of mortality, however, “Any morbidity in 2–5 month old calves is a concern and a goal of zero morbidity is reasonable,” he says.

Studies show a decrease in weaning weight of calves treated for BRD while nursing and an increase in morbidity and mortality in the feedlot. “I have posted a number of calves soon after weaning or in the backgrounding/preconditioning lot that are ‘found dead’ with no history of being sick that have chronic pneumonia; we feel these are calves that got sick while on the cow and never fully recovered,” Hilton explains. 

Calf respiratory case study

W. Mark Hilton, DVM, Dipl. ABVP, had some clients who experienced summer pneumonia in beef calves every year. With Hilton’s help and a change in management, things turned around. “This was a very well-managed herd where the husband, wife and sons were excellent managers and were very observant,” Hilton says.

Hilton and his clients started out vaccinating the calves with a killed vaccine and adding copper, selenium and zinc to the cow mineral as it appeared his mineral was deficient in these areas, but they saw no change in summer pneumonia the following year.

Later that year, numerous additional changes were made:

  • Cows were calved later in the spring.
  • The producers wintered cows and heifers in separate lots and then moved cows and heifers into new, "clean", separate calving lots.
  • Calving was done on pasture/cornstalk fields, not in the barn.
  • Cows were vaccinated prebreeding with MLV IBR-BVD-PI3 vaccine and then gave intranasal IBR-PI3 six weeks precalving. (Hilton says now he would use the same IM MLV IBR-BVD-PI3 vaccine since it is now labeled for pregnant cows).
  • Calves were vaccinated at 7–60 days of age at pasture turn-out with MLV IBR-BVD-PI3-BRSV vaccine. After the remainder of the cows calved (~10% of herd) pairs were brought to the working facility and calves were vaccinated with the same vaccine.
  • Continued to feed a balanced mineral mix.
  • Increased hybrid vigor via artificial insemination (AI) and bull purchases.
  • Heifers are bred AI to proven calving-ease bulls.

“This list may look really long, but many of the above are simply ‘best management practices’,” Hilton says. “I think this is pretty typical where we have a lot of little things adding up to a big problem. And when the producer’s wife came into the clinic one day and said ‘thanks to you we are going on a summer vacation’, that made me feel pretty good.”