Early diagnosis and treatment of respiratory disease is important to be successful.  Dr. Dan Cummings with Boerhinger says in Beef Magazine that nursing calves infected with respiratory disease could weigh up to 36 pounds less at weaning than their healthy herd mates.  That may not seem like a lot, but a replacement heifer that was infected as a young calf will breed later in life, produce less milk, and is more likely to be culled.  Bovine respiratory disease is mostly a problem for feedlot and stocker operations, but cow-calf producers should also be concerned as almost 20% of nursing calves will develop pneumonia.  To identify sick calves, Dr. Cummings has developed what he calls the D.A.R.T. or DART protocol.  The d stands for depression, as a sick calf will have droopy ears and hold the head lower than normal.  The a stands for appetite, as these calves usually have a reduced appetite and are slow coming up to eat and not nursing as frequently.  The r is respiration, as these calves usually cough and have labored breathing and flared nostrils as they breathe.  The t stands for temperature, and most of these calves with pneumonia will have an increased temperature over 104°F. 

However, all calves don’t always have all of these symptoms. Your veterinarian can diagnose these cases early by listening to the lungs with a stethoscope or using an ultrasound to examine the lung fields.  The antibiotic you choose should be determined by a culture of the organism from calves that have not survived.  However, it is important to make sure the antibiotic you choose initially covers the bacteria Manhheimia Hemolytica, Pasteurella Multocida, Histophilus Somni and Mycoplasma Bovis.