What is Foal Pneumonia?
Neonates, or foals younger than four weeks, and older foals, those over four weeks old, can have problems with weaning, or just not receive enough colostrum from their mothers. This causes a lack of immunity, and can predispose these young animals to infection. While bacterial infection is a common cause of pneumonia, other causes can include aspiration, or when the foal chokes on milk, food particles, or has an obstruction in its esophagus. Pneumonia often results from the bacteria or virus taking hold when there is opportunity to infect, but it can also be secondary to other health or congenital issues.
Pneumonia is an inflammation of the lungs, and is the main cause of death in foals one to six months of age. Signs of coughing, wheezing, nasal discharge, and breathing distress is a signal that something is going wrong and needs attention. While many cases of pneumonia can be successfully treated with antibiotics, severe cases can be fatal.
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Symptoms of Foal Pneumonia in Horses
Symptoms of pneumonia in foals includes:
- Wheezing or crackles while breathing
- Increased respiratory rate, over 30 breaths in a minute
- Struggled or labored breathing
- Lack of pulmonary function
- Lack of nursing or eating
- Foal’s head covered in milk, indicating weak nursing
- Mare’s udder is engorged, possibly streaming milk, indicating lack of nursing
- Growth retardation
- Yellow nasal discharge
- Elevated temperature
- Cyanosis, or bluish skin and mucous membranes
- Enlargement of lymph nodes
- Weight loss
Some types of pneumonia seen in foals include:
This is the most common type of pneumonia, and often results secondary to aspiration or bacteremia, or when the bacteria gains access to the bloodstream. Bacteria that normally lives in the upper respiratory tract is opportunistic, and in the right conditions, can lead to infection and pneumonia in neonatals. In older foals, bacteria is generally inhaled, often on dust particles.
This viral infection is more common in neonates, where it can be fatal. Equine Herpes Virus-1 infections result in inflammation and severe pneumonia. In older foals, EHV-1 and EHV-4 present milder symptoms, while the Equine Arteritis Virus can lead to sudden death.
This type is caused by the bacterium Rhodococcus equi, which is found in the soil. Most often occurring in foals 2 to 4 months old, it infects through inhalation, often of dust particles. When ingested, this bacteria can cause disease in the lungs, as well as in the gastrointestinal tract and musculoskeletal system. Besides pneumonia, it can cause diarrhea, abscesses, and septic joints, along with a host of other life threatening conditions. It is often not noticed until far progressed, and in many cases leads to death or euthanasia.
Aspiration can occur due to a genetic abnormality, an esophageal obstruction, difficulty swallowing, or if food or drink are inhaled into the trachea. Opportunistic or inhaled bacteria then have a chance to infect, causing the pneumonia.
Causes of Foal Pneumonia in Horses
Causes of pneumonia in foals include:
- Bacterial infection, such as Streptococcus zooepidemicus, Rhodococcus equi, Actinobacillus spp, Escherichia coli, Bordetella bronchiseptica, Klebsiella pneumoniae, Pseudomonas spp, Pasteurella spp, Staphylococcus spp and Salmonella spp
- Parasitic infection, such as Parascaris equorum
- Viral infection, such as Equine Herpes Virus-1 and 4, Equine Arteritis Virus, and Equine Influenza Virus
- Inadequate colostrum from mother in foal, resulting in a higher risk of infection
- Esophageal obstruction
- Congenital defect, such as cleft palate or sub-epiglottal cyst
- Accidental inhalation of food or liquid into windpipe
- Difficulty swallowing
- Combined immunodeficiency (CID), a hereditary disease in purebred Arabians
- Stressors that can increase a foal’s susceptibility, such as transport, crowded confinement, dusty conditions, or troubles with weaning
Diagnosis of Foal Pneumonia in Horses
Diagnosis of pneumonia in your foal is based on a physical examination that includes listening to the breathing with a stethoscope, symptoms, medical history, and the results of testing. Testing can also help determine the cause, such as if it is viral or bacterial, which will help with treatment. Blood tests, including a CBC, can be helpful with diagnosis and can help to monitor treatment response. Viral isolation and polymerase chain reaction (PCR) can detect the presence of a virus.
A tracheal wash is often performed to collect fluids for examination. The types of cells and the presence of food particles can help to determine the cause. Bacteria can be found with a sensitivity test, while cytology testing can detect specific bacteria, such as Rhodococcus equi.
Further testing includes chest X-rays or ultrasounds, which can help to identify abscesses or other lung abnormalities that can be suggestive of certain causes, such as Streptococcus zooepidemicus.
Treatment of Foal Pneumonia in Horses
Typically, appropriate antibiotics are given, sometimes intravenously. Severe cases may need hospitalization, where environment and supportive care can be easily monitored. An air-conditioned stall helps with cooling, while supplementary nasal oxygen is given until lungs are able to take in enough oxygen from the air on their own. A nebulizer may be used several times daily to administer antibiotics and bronchodilators.
Antimicrobial drugs will be administered in cases of Streptococcal pneumonia. Intravenous penicillin is given as needed. Treatment generally lasts at least 3 weeks, or the condition can recur.
In cases of Rhodococcus pneumonia, antimicrobials are also used, as well as macrolide therapy. Treatment may be needed for up to 3 months. In severe cases, the condition of your foal will be monitored through a CBC, ultrasound, X-ray, fibrinogen, and listening to lung sounds. In some cases, the infection is so overwhelming it can lead to death, or euthanasia.
Recovery of Foal Pneumonia in Horses
Supportive care in foals recovering from pneumonia includes rest, a cool and clean environment, and adequate hydration. Reduce stressful events, such as sales, transport, and weaning. Cases of pneumonia have a higher rate of recovery when treated with appropriate antimicrobials early. More severe cases can progress and lead to death.
Prevent pneumonia from affecting your foals by keeping them in clean, well-ventilated, and dust free areas. Reduce overcrowding, and house sick animals away from healthy ones. Rotate pastures to decrease dust formation. Keep new foals from different farms separated from your foals to reduce the spread of infectious agents. Remove manure frequently from stalls. Keep mares up to date on vaccines, and monitor your foals for any symptoms.