Calves most often become sick following stressful situations such as weaning or marketing. The clinical signs are usually seen 7-21 days after the calves are bought, but can occur anywhere from 2-30 days after purchase. Less frequently, calves that have not been marketed or weaned can develop pneumonia, usually related to weather changes or other stressors.
The most common and earliest recognizable clinical sign of pneumonia is depression. Calves exhibiting depression will have drooping ears, an extended head, a bowed back and/or often isolate themselves from other cattle. As these calves get progressively sicker, they will go off feed and will exhibit an increased respiratory rate. Increased lung sounds can be heard with the aid of a stethoscope. A thermometer is another useful tool in the diagnosis of pneumonia. Most sick calves will have a fever of 104°-108°F. However, temperatures can be falsely elevated in the afternoon due to increased outside temperatures. In order to obtain the most accurate temperature reading for an animal that is suspected to be sick, the calf's temperature should be taken before 10:00 am.
Developing a Treatment Protocol
There are four primary questions to be answered when developing a treatment protocol:
When do I treat the calf?
Early treatment of calves is the most important aspect of a successful treatment program. Therefore, calves should be observed often and when any of the clinical signs listed previously are detected, the animal's temperature and breathing sounds should be analyzed.
What will help this calf?
Aside from antibiotics, sick calves should be given excellent quality hay and grain. Grass and/or rye are also good feedstuffs as sick calves will often eat these when they will not eat anything else. Unless the weather is severe, calves often benefit from sunlight and being outside as opposed to being in a barn with poor ventilation.