Pneumonia in cattle is a complex disease with many causes and is difficult to prevent. Ruminants’ lungs are very small in relation to the size of the animal’s body. If even just a part of the lung is affected, it influences the animal’s ability to breathe.

Multiple Causes

A survey conducted over several years shows an increase in pneumonia among cattle during the transition from autumn to winter and from winter to spring. Conditions such as excessive dust, cold, poor nutrition (shortages of vitamins and trace elements) that lower the animal’s resistance, insufficient water, and stress can all lead to pneumonia.

Disease-causing organisms include viruses, fungi, nematodes (worms), foreign material (such as rumen contents and oral dosing agents), and bacteria. The upper airways of cattle normally contain bacteria, but the mucus lining of the windpipe constantly moves dust and bacteria to the throat where it is swallowed.

If animals are kept in very dusty conditions or exposed to extreme cold, this protective mechanism is hindered, allowing bacteria to move deeper into the airways, causing bronchitis and eventually pneumonia.

Symptoms

Some signs of the disease include a high fever that causes animals to stop eating and isolate themselves. Animals will often cough and there is usually a purulent (pus-like) nasal discharge. Breathing becomes progressively faster, and in advanced cases, the animal stands with its mouth open in an effort to draw enough air into its damaged lungs. If you listen to the chest, you may hear whistling or bubbling sounds, depending on whether the airways are narrowed or if there is moisture or pus present.

Figure 1: Progression of pneumonia. (Source: Vet Network)

By the time a farmer notices that an animal is sick, it has likely already been ill for three or four days. Early identification is therefore extremely important.

Several types of antibiotics help fight the common bacteria that cause pneumonia. Stronger antibiotics are available only with a veterinarian’s prescription, as indiscriminate use can lead to resistant bacteria.

Prevention Tips

Cases can be limited by applying good management practices. Vaccinate early against the viruses and bacteria that can cause pneumonia. Vaccines usually contain two or more of the organisms responsible for the disease.

Ensure cows are in good condition when they calve, so the calves receive high-quality colostrum. If an animal becomes so sick that it lies down, make sure it doesn’t lie on its side and inhale rumen content. Animals that are dosed with medication must be well cared for.

Spray roads around kraals and feedlots with water to prevent unnecessary dust exposure. Good biosecurity is important. Buy animals only from reputable sources and isolate new animals for four weeks.

The Feedlot Environment

Feedlot cattle are at greater risk of developing pneumonia. Here, biosecurity and early detection are especially important. Samples can be taken from animals that have already died to choose the most effective antibiotics.

In all cases, postmortem examination and sample collection are the best way to accurately diagnose the organisms involved. An effective vaccination program can then be developed in collaboration with the herd veterinarian. Immunization remains the best line of defense.

Article by Mr. Koos du Pisanie, Veeplaas, with contributions by Dr. Kobus Grobler and Dr. Danie Odendaal.