Aspiration Pneumonia in Horses

Key Takeaways

Aspiration pneumonia is an infection of the lungs caused by inhalation of a foreign substance. It is more common in foals, but can be seen in horses of any age. 

• Aspiration pneumonia is caused by anything that can interfere with the swallowing process, which allows foreign matter into the lungs including cleft palates, obstruction of stomach outflow, or a mass in the throat

• Common symptoms include difficulty breathing, increased respiratory rate, fever, lethargy, and coughing

• Diagnostics include physical exam, medical history, diagnostic imaging, tracheobronchial aspiration, and endoscopy

• Treatment can involve fluid drainage of the lungs, antibiotics, tube feeding, thoracocentesis, and anti-inflammatories

• Prognosis for horses that have begun to show symptoms of aspiration pneumonia is poor and it is recommended to begin antibiotics before symptoms appear if fluid aspiration is suspected

A Closer Look: What is Aspiration Pneumonia in Horses?

Aspiration refers to any occurrence where liquid or solids are inhaled and end up in the lungs or breathing apparatus. Aspiration can lead to infection, resulting in pneumonia, which is life threatening.

Horses with severe aspiration pneumonia may have inadequate oxygen delivery to their tissues. Symptoms of oxygen deprivation include:

• Blue tinged gums (cyanosis)

• Rapid breathing

• Difficulty breathing with abdominal effort

Risk Factors

This condition is most commonly seen in foals, but can also occur in adult horses. Severity depends on what was inhaled, what bacteria may have been present, and the volume and spread of the material in the lungs.Aspiration pneumonia has a poor prognosis, even with treatment, so prevention is the most important measure. 

Aspiration can happen to any mammal for a variety of reasons, but it is common in nursing foals (liquid diet) and those with deformities or underlying conditions which interfere with the normal swallowing apparatus. 

Horses with cleft palates, horses that are choking, horses under anesthesia, and horses with difficulty swallowing are at an increased risk as the ability to swallow is impaired or limited. Constant monitoring and careful management are necessary.

Nasogastric intubation is commonly performed on horses to relieve symptoms of colic, and a misplaced tube can result in aspiration. As such, intubation of horses should only be performed by a veterinarian. There is no safe way to intubate horses at home.

Possible Causes

In foals possible causes include:

• Cleft palate

• Obstruction of stomach outflow, leading to reflux

• Improper placement of nasogastric tube

• Difficulty swallowing due to dysfunction inside the throat

In adult horses possible causes include:

• Choke

• Improper placement of nasogastric tube

• Difficulty swallowing due to a mass pressing on the inner throat, such as swollen lymph nodes, tumor, abscess

• Neurologic disorders (botulism, equine encephalitis virus)

• Megaesophagus

Main Symptoms

Symptoms of aspiration pneumonia include;

• Difficulty breathing

• Increased respiratory rate

• Fever

• Lethargy

• Coughing

• Nasal discharge

Testing and Diagnosis

In addition to physical exam and medical history, diagnostic tools include:

• Bloodwork

• Diagnostic imaging 

• Tracheobronchial aspiration: analysis of fluid from the lungs

• Endoscopy: investigation of the lungs with a camera

Steps to Recovery

Once aspiration pneumonia is confirmed, treatment is prolonged and aggressive. This can include:

• Nasogastric tube feeding in horses having difficulty swallowing

• Supplemental oxygen

• Thoracocentesis: removing fluid accumulating in the chest

• Antibiotics

• IV fluid therapy

• Anti-inflammatory medications

Prognosis is guarded. There is a high incidence of fatality, and severe complications are common. Complications can include pleuritis (inflammation of the lung lining), lung abscesses, laminitis, and septicemia. These complications often lead to euthanasia.

Prevention

The primary method of prevention is to avoid aspiration (inhalation of liquid or solids) in the first place. The most common substance that causes aspiration pneumonia in horses is liquid medications given too rapidly. All liquids should be administered no faster than the horse can swallow to prevent inhalation.

In addition, if there is a suspected aspiration, it is best to begin a treatment of antibiotics before symptoms of pneumonia have appeared. Horses suspected of inhaling foreign material require emergency veterinary care. 

Aspiration pneumonia is not contagious.

Is Aspiration Pneumonia Common in Horses?

Aspiration pneumonia is uncommon in horses, but more common in horses with predisposing factors that interfere with normal swallowing.

Typical Treatment

• Nasogastric tube feeding

• Supplemental oxygen

• Thoracocentesis

• Antibiotics

• IV fluids

• Anti-inflammatories