Question:  EIPH (Exercise Induced Pulmonary Hemorrhage) is common in race horses, yet there is no record of it in the history of the Pony Express where the horses galloped 10 to 15 miles between relay stations. There is also no record of EIPH in wild horse roundups that happen now, where the horses are rounded up with helicopters from mountain tops to pens miles away and all sorts of problems are recorded, including coming in sore footed, but never any bleeding. How can this discrepancy be explained?

Answer: There is really no discrepancy. Endurance horses racing for long distances at similar speeds as Pony Express horses don’t show EIPH. Bleeding appears to require intense bursts of speed and intense effort. Your wild horse observation may or may not be true. Distance isn’t the problem; speed is. Regardless, no one expected EIPH was so prevalent in race horses, barrel racers or polo ponies until systematic endoscopic examinations were performed. I don’t know if any studies have been attempted in wild horses; they would be quite a challenge. An easier approach may be to examine lung tissue from wild horses, which have died looking for tell-tale pathological changes in their lung tissue.

Question: What is the best treatment for tying-up and does it have anything to do with electrolyte imbalance?

Answer: Tieing up has always been associated with an electrolyte imbalance but is more likely due to varying levels of exercise and diet. Potassium levels are important but difficult to measure. The best treatment is to prevent the condition before it occurs through a consistent feeding plan and a consistent exercise program. Once a horse ties up, it is important to decrease the ongoing damage by running fluids to keep the kidneys functional. Banamine and dexamethasone are two medications I reach for at this time. BC2A paste is a good preventative and I recommend feeding KCL salt daily. Dantrium or acepromazine are medications that work to help prevent this condition. Continued problems with tieing up warrant more aggressive treatment and prevention.

Question: What are a handful of causes and precursors for a lightly raced and retired sprinter, barely into their double digits, to have a hole in the diaphragm? How would the symptoms of a diaphragm hole present to the practical caregiver? What would be the lifestyle precautions and prognosis for such a horse?

Answer: Diaphragmatic hernias are rarely seen by us. They are usually caused by blunt trauma such as horses colliding on the track, sometimes kicks that are complicated by fractured ribs, or falls on the track. They are like most hernias in that the horse can do fairly well with the hole present but can start to experience problems when other structures such as loops of intestine start to become entrapped within the hole in the diaphragm. Therefore, signs observed would vary from increased respiratory rate to colic signs with or without toxicity due to degrading bowel. They certainly can be a life threatening situation at that point. Surgical repair would be required in this situation and the prognosis would depend on the amount of tearing and the degree of compromise to the gut. That's the bad side. Horses can and do live with chronic hernia, though, and may not show significant signs for years. As far as precautions to optimize health, I would recommend to keep the horse on a consistent diet and keep the exercise moderate. I don't know what plans you would have for this horse, but I would probably not look for this horse to be in strenuous activity. Jumping and eventing-type exercise might not be in his best interest. There are reports of stallions injuring their diaphragms during breeding, so that might be a risk factor as well.

Reprinted with permission from AAEP. To view the entire article please visit www.aaep.org/ask_the_vet.php