Proton Pump Inhibitors (PPIs) suppress acid production in the stomach. Accurate dosing can be very tough to estimate, and excessive use can lead to poor digestion of food and longer term health problems.
PPIs aim to shut down gastric acid production in the stomach by direct inhibition of the proton pump. The only PPI licensed for horses in the U.S. is omeprazole, marketed as Gastro Guard®.
Drugs have many shortcomings, and proton pump inhibitors have some unique ones. When your horse builds a tolerance after prolonged daily use, you find yourself continually increasing the dosage to achieve the same results.
These side effects are very accurately described in the PDR/Physician’s Desk Reference for humans, as these drugs have been used for humans much longer than for horses.
Other studies list other common side effects for these types of acid blocking drugs such as: abdominal pain, diarrhea, headache, nausea and vomiting.
Less common effects you could experience include; abdominal swelling, aggression, anemia, anxiety, apathy, back pain, blood in urine, changes in liver function, chest pain, confusion, constipation, cough, depression, difficulty sleeping, discolored feces, dizziness, dry mouth, dry skin, fatigue, fever, fluid retention and swelling, fluttery heartbeat, frequent urination, gas, general feeling of illness, hair loss, hallucinations, hepatitis, high blood pressure, hives, irritable colon, itching, joint and leg pain, loss of appetite, low blood sugar, muscle cramps and pain, nervousness, nose bleeds, pain in testes (!), rapid heartbeat, rash, ringing in ears, sleepiness, slow heartbeat, stomach tumors, upper respiratory infection, urinary tract infection, vertigo, weakness, weight gain and yellow eyes or skin. Just what you want in a reliable mount-NOT!
The driving factors that lead to a horse suffering from excessive digestive acidity in the first place are not addressed when solely using these drugs. Re-evaluate your feed program, and water quality, if you are considering use of PPI drugs.