What is Rhodococcus Equi Pneumonia?
Rhodococcus equi is the bacterial culprit of this form of pneumonia in foals. It is believed this infection can originate within the first week of life. This bacterium can be found in the soil in many locations and can be picked up by your foal via inhalation. It is typically seen in foals between 1 to 4 months of age and causes rapid deterioration. Clinical symptoms can be vague, but blood work and radiographic images of the lungs produce findings specific to this type of pneumonia. These diagnostics will allow for appropriate identification of the bacteria causing your foal’s illness and therefore appropriate treatment can be administered. Veterinary treatment must be started immediately if you want your foal to have any chance of recovery. If you do seek veterinary care, prognosis for your foal is good.
Rhodococcus equi pneumonia is the most serious and life-threatening form of pneumonia seen in young foals. The symptoms can appear suddenly and can result in death if left untreated.
Book First Walk Free!
Symptoms of Rhodococcus Equi Pneumonia in Horses
Symptoms you may see in your foal can occur acutely. Symptoms may include:
- Purulent nasal discharge
- Crackles and wheezes on thoracic auscultation
While it is not the most common cause of pneumonia in foals, Rhodococcus equi pneumonia is the most serious. It affects foals 1 to 4 months old but rarely foals 8 months or older. The infection progresses slowly in your foal but clinical symptoms can manifest acutely. Since symptoms aren’t seen until it reaches a critical condition, it makes treatment difficult.
Causes of Rhodococcus Equi Pneumonia in Horses
Rhodococcus equi pneumonia is caused by the gram-positive bacteria Rhodococcus equi. It is an intracellular pathogen that is found in soil and inhalation of these particles or dust particles containing it are the main causes of this type of pneumonia. The manure of an infected foal is a major source of the bacteria which leads to recontamination if not kept clean. It should also be noted foals suffering pulmonary infections from R. equi are continuously swallowing sputum laden with the bacteria, leading to replication in his intestinal tract.
Diagnosis of Rhodococcus Equi Pneumonia in Horses
Your veterinarian will begin by performing blood work. A complete blood count (CBC) and chemistry panel will be run. The results will give the veterinarian information on whether your foal is indeed fighting some type of infection. The two levels related specifically to your foal’s prognosis is severity of neutrophilic leukocytosis and hyperfibrinogenemia.
The veterinarian will also want to take radiographs to look at the foal’s lungs. She will be checking for patterns of alveolization, consolidation, and abscessation. In causes of Rhodococcus equi pneumonia, the lungs take on the appearance of having nodular lesions and mediastinal lymphadenopathy. Radiographs of the gastrointestinal tract may also be taken to check for lesions or abscesses in the area. If so, this can lead to additional symptoms and treatments.
For a definitive diagnosis, a tracheal wash sample will need to be collected. The veterinarian will run a culture on it which will allow her to prescribe the proper antimicrobial medication for your foal as soon as possible.
Treatment of Rhodococcus Equi Pneumonia in Horses
Antimicrobial medications should be started immediately. Most veterinarians use a combination of erythromycin and rifampin which has been shown to improve the foal’s chance of survival. However, these medications can cause your foal to experience side effects like diarrhea, tachypnea, and anorexia. There has also been an appearance of R. equi resistant to these two commonly used antimicrobials.
You will also need to provide your foal with supportive therapies. A clean environment is vital in treatment so he does not re-infect himself. He should be offered soft, palatable, dust-free feeds. Intravenous fluid therapy should be started along with oxygen therapy. If your foal is experiencing a significant amount of pulmonary exudates, the veterinarian may use saline nebulization to encourage expectoration. Your veterinarian may also administer an antiulcer medication as a prophylactic if the foal is stressed by his illness, hospitalization, and handling.
Recovery of Rhodococcus Equi Pneumonia in Horses
If you do not seek immediate veterinary attention for your foal for the treatment of Rhodococcus equi pneumonia, rate of fatality is very high. However, if you seek the proper treatment as soon as possible, survival rate is good. Treatment can be expensive and time consuming, but you cannot discontinue therapy until all symptoms and tests determine your foal is clear of R. equi.