Investigation into the Presence of Helicobacter in the Equine Stomach by Urease Testing and Polymerase Chain Reaction and Further Investigation into the Application of the 13C-Urea Blood Test to the Horse

Equine gastric glandular mucosal ulceration can have a prevalence of 58%, yet its etiology is poorly understood. In man Helicobacter pylori is the most common cause of gastritis and peptic ulcer disease. Helicobacter is uniquely able to colonize the stomach, via the action of cytoplasmic urease. Different Helicobacter species have been isolated from many mammals but none has yet been cultured from the horse. Three tests used to identify human Helicobacter infection were applied to the horse. Test 1: PCR amplification of Helicobacter specific DNA, n=12. Test 2: the Pyloritek™ rapid urease test (RUT), n=15. Test 3: the 13C-urea blood test, n=8. Gastroscopy and antral biopsy was performed in all horses.

All horses demonstrated the presence of Helicobacter specific gene material by PCR. Biopsy specimens from 7/15 horses were urease positive by RUT. Significant 13C enrichment of the body CO2 pool was found in all horses after intragastric administration 13C-urea (p<0.05). As Helicobacter is currently the only known gastric urease positive microorganism, the demonstration of this activity in horses positive by PCR strongly supports the presence of an equine gastric Helicobacter species.

Variations of 13C-urea blood test were further examined and a single protocol was found to be most applicable. As the horse is a hind gut fermenter, the effect of cecal urease on the test was examined by laparoscopic intracecal administration of 13C-urea. Significant cecal urease activity was demonstrated however the timing of peak 13C enrichment may limit any effect on the gastric test to 90 minutes onwards.