Clinical Case Challenge

Distressed, dehydrated horse, unable to eat
Mustang horse in desert.
Stock photo of Mustang horse. Photo: iStock/JenDeVos

Clinical Case Challenge: Mustang with Common Condition in Older Horses

Jojo, a 35-year-old mustang, was presented to Cummings School of Veterinary Medicine’s  Hospital for Large Animals in distress. He was regurgitating a mixture of saliva and food from his nostrils, and frequently stretched out his neck and retched. Jojo was markedly dehydrated, but unable to drink.

While Jojo had experienced eating issues in the past, the severity of symptoms prompted his owners to call in their veterinarian, Dr. Al Andersen, who immediately recognized Jojo’s ailment and began treatment at the farm. When this was unsuccessful, Dr. Andersen referred Jojo to the internal medicine team at Hospital for Large Animals. 

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Determine which diagnostics and treatments are required
When Jojo arrived at Hospital for Large Animals (HLA), he had a profuse discharge of feed and saliva coming from his nose, and was clearly uncomfortable. On clinical examination he was markedly dehydrated and had a fever.

“The external signs showed what was going on,” said Dr. Melissa Mazan, V93 (she/her), professor and internal medicine clinician at Hospital for Large Animals.

Equine veterinarians are familiar with the signs of esophageal obstruction, also known as “choke,” a condition common in older horses. When hay or feed becomes stuck in a horse’s esophagus, the horse will continue to swallow and chew, but the food won’t reach the stomach. Large amounts of saliva and food will be seen coming from the nostrils. The horse will become distressed and inhale food into the trachea and lungs, which frequently causes aspiration pneumonia. Unable to drink, while also losing large quantities of fluids through saliva, the horse will also become dehydrated.

While the clinical signs of choke can be readily diagnosed on the basis of history and clinical examination, other comorbidities may be more subtle and require further diagnostics, such as electrolyte disturbances due to loss of chloride, bicarbonate, and sodium in the saliva, aspiration pneumonia, and secondary renal disease. Accordingly, HLA internal medicine team also diagnosed Jojo with secondary pneumonia and renal disease. Resident Dr. Mireya Becero-Lopez and a team of Cummings School veterinary technicians and students worked together with Dr. Mazan to assess and treat Jojo.

Immediate treatments: removing the obstruction and rehydration
The doctors used an endoscope and other specialized equipment to carefully pick away at the obstruction in Jojo’s esophagus and fully remove it. Jojo was lucky—while the surface of the esophagus was inflamed and abraded where the obstruction had been, he had no significant tearing of the mucosa or underlying tissue.

“The treatment is also the diagnosis to a certain extent. With the endoscope we could see the bolus of poorly chewed hay and feed that was causing the obstruction,” said Dr. Mazan. 

Jojo received intravenous fluids to treat his dehydration and was started on broad spectrum antibiotics while the team awaited results of further diagnostics.

Diagnostics: serial bloodwork, x-rays, and ultrasound
The internal medicine team ran a complete blood count with fibrinogen and a chemistry profile, and noted an elevated level of creatinine, which indicated either continued dehydration or renal disease. Chest radiographs confirmed aspiration pneumonia. The team also performed an ultrasound to further characterize his respiratory issues, as horses with aspiration pneumonia can often develop accompanying pleuritis. The team was glad to see that there was no significant fluid accumulation in the pleural space, as that would have made the treatment more difficult. 

Treatments: antibiotics, Gastrogard, Bio Sponge, and home care
Jojo continued a course of broad spectrum antibiotics—a combination of ceftiofur (Naxcel) and metronidazole to treat the pneumonia. While the doctors were concerned that the antibiotics could disturb Jojo’s gastrointestinal microbiome and cause diarrhea, their first concern was his pneumonia, which, if left untreated, could be fatal.

During the first few days of hospitalization, Jojo’s esophagus was still recovering from the trauma of the obstruction, so he was only allowed to eat very soft foods. Jojo’s fever abated, but, as the team had feared, he developed diarrhea. The team treated the diarrhea with a fecal transfaunation, which involves giving the horse fresh fecal contents from a healthy horse to help repopulate the gut with good bacteria. The diarrhea subsided and Jojo’s creatinine slowly descended into normal range, but he lost his appetite. 

“Although Jojo was on broad spectrum antibiotics, including metronidazole, which can lead horses to inappetence, we were worried that the biggest problem was that Jojo was not happy in the hospital. He did not want to eat,” said Dr. Mazan. “Horses—especially older horses like Jojo who have lived with very dedicated owners for years—are used to home. They want their people, their stall, their pasture. They live very happily with a certain routine.”

While it would take more time for Jojo to recover from pneumonia, the internal medicine team felt he would fare better at home, and Jojo’s owners and veterinarian were both keen to try. They continued his care at the farm, monitoring his antibiotics and bloodwork, administering intravenous fluids, and staying in close touch with the team at HLA. 

Soon after returning home, however, Jojo again developed diarrhea and fever despite being on the same antibiotics that he had had at Cummings School. 

“We were concerned that there was a resistant bacterial population that the current antibiotic regimen was not addressing,” said Dr. Mazan. “While we were worried that an antibiotic change might worsen his diarrhea, we knew that we couldn’t let the pneumonia get out of hand. We also put him on Bio Sponge, and Dr. Anderson helped the owners manage his treatment at home.” 

To everyone’s relief, the fever and diarrhea soon dissipated, and a few days later, Jojo was well enough to come off the antibiotics. He remained on the Bio Sponge for another week and Gastrogard for a month. The horse soon regained weight, and his owners are now riding him again.

“If horses are happy and eat properly, I think it affects everything about them and their body system,” said Dr. Mazan. “Jojo looks 15 years younger. We are delighted, it’s more than we expected. To be able to return to this is a big win. It takes a lot of management and a good veterinary team—a combination of a specialty hospital, an astute vet at home, and caring and attentive owners.”

Comments from Cummings School’s Internal Medicine Team
“We remove esophageal obstructions frequently because with better feeds and veterinary care, there are so many older horses these days. We see many diseases of age now,” observed Dr. Mazan. “Horses’ teeth are continually growing out as they age, and by the time horses are in their teens, they mostly run out of good chewing surface and are prone to obstruction of the esophagus. Food gets balled up and stuck, which can be very painful. Occasionally we see choke in younger horses that are greedy eaters or have bad teeth, but it primarily happens in older horses.”

To prevent choke in horses, Dr. Mazan recommends softer feed and good dentistry to preserve the chewing surface, though she acknowledges that prevention is difficult because horses tend to eat what they want to eat.

Although many cases of choke are treated successfully in the field, when the obstruction cannot be quickly resolved, it’s urgent that horses get to a hospital like the HLA.

“If you have a difficult or unusual problem, you want the specialized care—diagnostics, radiology, pathology—all in one place,” said Dr. Mazan. “Aspiration pneumonia is the most common sequela of choke, and electrolyte abnormalities and renal compromise are common, but even more serious is the potential for esophageal rupture and ensuing sepsis—it’s very difficult to save the horse once that has happened. When Jojo’s veterinarian realized that the choke was not yielding to treatment, he sent Jojo to us right away. That decision is what saved Jojo’s life in the long run.”