Pleuropneumonia in a Horse

A 17 year-old gelding QH presented for a 3 week history of intermittent fever and coughing.

History:

The gelding had been treated with 3 different antibiotics over the past 3 weeks and there were no improvements in clinical signs. The problem started after the horse had been transported approximately 12 hours via truck and trailer. Within 24 hours of arriving to the show grounds the gelding was sick!

Physical exam:

When I examined the horse, the gelding was in distress! His heart rate was 80 bpm, respiratory rate was 60-70 bpm (shallow) and his body temperature was 102 degrees. Auscultation of the thorax noted lung sounds (sound of air moving in and out of lungs) on both sides of the horse only ABOVE the level of the shoulder but lung sounds were absent or muffled below the level of the shoulder. Suspecting pleuropneumonia, I performed a trans-thoracic ultrasound exam. A significant amount of fluid was noted in the pleural space along with large fibrin tags and multiple abscesses! ( Figure 1-3).

 

 

 

 

 

Figure 1

 In the video clips below, the fibrin tags can be seen "floating" in the excessive fluid within the pleural space. In addition, the fluid appears as "cellular" suggesting a heavy component of fibrin and purulent debris (pus).

In Figure 2-3, large abscesses are noted adjacent to the body wall. Ultimately, these abscess would need to be exteriorized through a rib resection in order for the horse to completely heal. Unfortunately, the ultrasound findings combined with the severe physical distress were very poor prognostic indicators and the owner elected humane euthanasia!  There was near zero chance that this horse could have been saved regardless of the medical and surgical intervention provided!

Figure 2

Figure 3

Pleuropneumonia in also called pleurisy and refers to bacterial infection of the pleural cavity and the surrounding soft tissue structures. This condition is VERY deadly and originates from bacterial colonization of the lower airway! The condition is more common in young horses that are transported long distances on a regular basis. Hence the term "shipping fever". A common belief is that horses which are transported with their head tied and a bag of hay in front of them are predisposed because they are not able to properly clear their airway of airborne debris and pathogens. Normally, horses eat with their head down which minimizes the passage of unwanted matter down their trachea and into their lungs.  This condition can be treated effectively if diagnosed early, i.e, within 1-2 days of clinical signs! Aggressive medical treatment is a must and includes IV antibiotics, chest drainage/lavage, and supportive care. One of the most painful horses I witnessed as a resident was a young filly with pleurisy!! Looked like a bad case of colic but was in fact pleuropneumonia!!

Dysphagia and Aspiration Pneumonia in a horse!!

The endoscopy images below were from a young gelding that presented for a history of coughing while eating. In addition, an intermittent nasal discharge was present and the gelding was described as a "hard keeper". In Figure 1, a small amount of feed material was noted along the floor of the soft palate, just in front of the epiglottis. In addition, feed particles were noted on the epiglottis and the walls of the pharynx. These findings alone are not 100% indicative of a dysphagic (difficulty swallowing) horse however, generally speaking there should NOT be any feed material in the pharynx or larynx. 

Figure 1

When the endoscope was passed through the larynx into the trachea (wind pipe) copious amounts of feed material mixed with mucus was noted on the walls of the trachea. In Figure 2, green and brown feed material  can be seen adhered to the wall of the trachea. As the endoscope was pass further down the trachea, feed material mixed with mucus remained present in significant amounts. 

Figure 2

At the very end or deepest region of this image (Figure 3) is the primary bifurcation of the trachea which occurs just in front of the heart. The presence of feed material at this level of the airway is consistent with aspiration and a trans-tracheal wash was performed to confirm pneumonia.  

Figure 3

Dysphagia and aspiration pneumonia are quite uncommon in horses and may be secondary to a neuropathy affecting the nerves that control the swallow reflex. The most common disease processes in horses that may affect these nerves include equine protozoal myeloencephalitis (EPM), cervical spine trauma, trauma to the guttural pouches, temporohyoid osteopathy (THO), strangles, encephalitis, and basisphenoid bone fracture. Unfortunately, the prognosis is poor for horses with this condition. The likelihood that they will recover their normal swallow reflex, regardless of the cause, is low!  In addition, the aspiration pneumonia that results from the dysphagia  is a recurring problem that typically results in their failure to thrive!