Comparison of 5- and 7-day Interval Dosing with Long-acting Injectable Omeprazole in the Treatment of Equine Squamous and Glandular Gastric Disease

Background: Long-acting injectable omeprazole (LAIO) has become a popular treatment for equine squamous gastric disease (ESGD) and equine glandular gastric disease (EGGD) where it is available, however the optimal treatment interval has not been determined. 
Objectives: To compare rates of healing of ESGD and EGGD when long-acting injectable omeprazole is administered at either 5- or 7-day intervals. 
Study design: Retrospective clinical study. 
Methods: Case records and gastroscopy images of horses with ESGD or EGGD treated with LAIO were reviewed. Images were anonymised and graded blind by one researcher. Treatment responses were compared between the two treatment schedules using univariable logistic regression.
Results: Forty-three horses were treated with LAIO at 5-day intervals, and 39 at 7-day intervals. Signalment and presenting signs did not differ between groups. The rates of EGGD healing (to grade 0 or 1) associated with LAIO at 5-day intervals (93%) was higher than associated with treatment at 7-day intervals (69%, p = 0.01). For ESGD, there was no significant difference in the rate of healing associated with treatment at 5-day intervals (97%) compared to 7-days intervals (82%, p = 0.07). Four localised injection site reactions were reported out of 328 injections (1.2%). 
Main limitations: Retrospective study design, lack of randomisation and limited case numbers. 
Conclusions: The use of LAIO at 5-day intervals resulted in superior rates of EGGD healing and may be more appropriate than the 7-day interval. 
Ethical animal research: Research ethics committee oversight not required by this congress: retrospective data collection. 
Informed consent: Not stated. 
Competing interests: D. Rendle provides consultancy services to the manufacturers of long-acting injectable omeprazole. 
Sources of funding: None.

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