Walking On Volume 4, Issue 5, May 2017 | Page 8

For the Health of It

Is Your Horse on Bute ? Consider Something Other than Omeprazole to Prevent Ulcers

by Juliet M . Getty , PhD
Bute ( phenylbutazone ) is the most commonly used NSAID ( non-steroidal anti-inflammatory drug ) for pain resulting from injury to the joints and feet . But while you ’ re relieving your horse ’ s pain , you may be putting him at risk of developing an ulcer . Here ’ s why …
Bute functions by blocking the cyclo-oxygenase ( COX ) enzymes responsible for converting arachidonic acid ( a fatty acid ) to prostaglandins , some of which contribute to pain and inflammation . There are two types of COX enzymes , COX-1 and COX-2 , which differ in their impact on your horse ’ s digestive system . COX-2 is the one we want to inhibit because it is involved in producing the problematic prostaglandins . COX-1 , however , is a beneficial enzyme that maintains a healthy gastrointestinal lining and also promotes proper blood clotting . Unfortunately , bute blocks both of these enzymes , alleviating your horse ’ s discomfort ( because it blocks COX-2 ), but making the mucosal lining of the stomach more vulnerable to stomach acid ( by blocking beneficial COX-1 ), potentially leading to ulcerations anywhere along the digestive tract .[ i ]
Bute disrupts the natural surface barrier within the stomach ’ s mucosal lining . Within this lining is a fatty bilayer made up of two rows of molecules called phospholipids . The outer portion is hydrophilic ( attracted to water ) while the inner portion is hydrophobic because of its fat content . Because bute inhibits COX-1 , it causes the inner hydrophobic barrier to become hydrophilic , allowing acid to permeate the mucosal lining , resulting in ulcerations .
To protect against ulcers , many vet-
8 • Walking On
erinarians will prescribe omeprazole
Produced by Merial , omeprazole goes by the brand names of the fullstrength GastroGard ® used to treat ulcers or the lower-dosed , UlcerGard ®, used to prevent ulcers while the horse is receiving bute . There is some justification for using this . Omeprazole is a proton-pump inhibitor which blocks the final step of acid production within the stomach . Since the protective mucus lining of the stomach may be compromised by bute , it becomes vulnerable to acid . Omeprazole reduces the acid content of the stomach , thereby preventing the formation of ulcers .
But there are real concerns with continued use of omeprazole . You may not be aware that :
1 . Sudden discontinuation of omeprazole can cause a rebound acid effect , at increased levels , making your horse more vulnerable to ulcer formation .[ ii ]
2 . Omeprazole can lead to malnutrition because stomach acid is necessary to start protein digestion and absorption of key minerals .
3 . Omeprazole doesn ’ t protect against ulcers that may show up in the colon .
Allow your horse ’ s stomach to do its job
Your horse ’ s stomach is meant to produce hydrochloric acid ( HCl ). HCl is needed to activate pepsin , an enzyme that starts to break down large protein molecules so they can later be completely digested in the small intestine down to individual amino acids . Amino acids are the building blocks of the proteins found throughout your horse ’ s body . If the protein in your horse ’ s diet is not adequately digested , amino acids will not be available to produce and repair body tissues . Furthermore , minerals found in feedstuffs are typically bound to proteins , making protein digestion necessary in order for these minerals to be released and absorbed .[ iii ]
Nevertheless , when COX-1 is inhibited , acid becomes the enemy because it can seriously damage the compromised mucosal layer throughout the stomach and the entire gastrointestinal tract .
Turning off stomach acid is not the answer
Well , it ’ s an expedient solution . And it relieves the symptoms , but it doesn ’ t truly undo the damage that bute has inflicted . Think about it … the lipid bilayer has been damaged by inhibiting COX-1 , making it vulnerable to acid . Removing the acid doesn ’ t take away the fact that the bilayer is damaged . Why not just prevent damage or repair it instead ?
There are two important foods you can add to your horse ’ s diet that can prevent or repair gastrointestinal damage from bute :
• Lecithin plus apple pectin
• Colostrum
Researchers from the University of Texas [ iv ] Department of Integrative Biology and Pharmacology described this mechanism using human subjects on NSAIDS ( in particular , aspirin and naproxen ). They created a formula that combines the NSAID drug with phosphatidylcholine ( PC ). When PC combines with NSAIDs , it creates a complex that is more fat-soluble , thereby promoting its transit across the hydrophobic mucus layer of the stomach , with reduced surface mucosal injury , while not altering the efficacy or pharmacological activity of the NSAID .