Study links forage gaps, age, and dental issues to equine gastric disease
Bottom line
Version 1
A prospective Equine Veterinary Journal study followed 80 extensively pasture-managed Icelandic horses across four farms in three regions of Iceland, with gastroscopy performed four times between May 2023 and February 2024. The researchers found that clinically significant equine squamous gastric disease, or ESGD, was present in 48% to 72% of horses across the year, while clinically significant equine glandular gastric disease, or EGGD, was present in 33% to 45%. Key risk factors for ESGD included reduced grass availability without added forage, southern geographic region, and higher body condition score. For EGGD, risk factors included concurrent ESGD, older age, and dental abnormalities. The paper adds to a growing body of work from the same research group showing that gastric disease in Icelandic horses isn't limited to animals in intensive training. (researchgate.net)
Why it matters: For equine veterinarians, the findings are a useful reminder that pasture turnout alone doesn't rule out gastric disease risk. In this cohort, moderate to high prevalence persisted in horses that were extensively managed and not fed the high-starch diets often associated with ulcer risk. That shifts attention toward practical herd-level factors, especially seasonal forage availability, body condition, age, oral health, and regional management differences. It also supports including gastric disease in the differential for older or dentally abnormal horses, even when pet parents and farm managers describe the horses as living in low-intensity, “natural” systems. (researchgate.net)
What to watch: Watch for follow-up work on whether targeted forage supplementation, dental interventions, or region-specific management changes can lower ESGD and EGGD rates in extensively kept horses. (researchgate.net)
Key facts
- Study type
- Prospective cohort study
- Journal
- Equine Veterinary Journal
- Sample size
- 80 extensively kept Icelandic horses
- Study period
- May 2023 to February 2024
- Assessment times
- Four gastroscopy timepoints
- ESGD prevalence
- 48% to 72%
- EGGD prevalence
- 33% to 45%
- ESGD risk factors
- Reduced grass without added forage, southern Iceland, and higher body condition score
- EGGD risk factors
- Concurrent ESGD, older age, and dental abnormalities
Version 2
A new Equine Veterinary Journal paper suggests that gastric disease remains common in extensively kept Icelandic horses throughout the year, challenging the assumption that pasture-based management is broadly protective. In the prospective cohort study, investigators gastroscoped 80 horses at four timepoints over one calendar year and found significant ESGD prevalence ranging from 48% to 72%, with significant EGGD prevalence ranging from 33% to 45%. (researchgate.net)
The study was designed to answer an open question from earlier work: whether the high gastric disease burden previously observed in Icelandic horses during autumn and winter was seasonal, or part of a more persistent pattern. The same research group had already reported that Icelandic riding horses in training could show meaningful gastric ulcer prevalence, and outside commentary has noted that these horses were chosen in part because the population had been relatively understudied. This new longitudinal design extends that work by tracking extensively grazed horses from May 2023 through February 2024. (researchgate.net)
The strongest management signal in the new paper was forage-related. Horses facing reduced grass availability without additional forage had markedly higher odds of significant ESGD than horses with low grass availability that did receive forage supplementation. Region also mattered, with horses in southern Iceland showing higher ESGD odds than those in the north. Higher body condition score was associated with ESGD, while older age, dental abnormalities, and the presence of ESGD were linked with higher odds of EGGD. The authors also flagged herd-size-associated social factors as a possible contributor to ESGD under these conditions, though that appears to be an inference from the risk modeling rather than a directly measured causal mechanism. (researchgate.net)
Those findings are notable because they complicate a familiar clinical narrative. Gastric ulcer risk is often framed around confinement, training intensity, and concentrate feeding. But this study found moderate to high ESGD prevalence and moderate EGGD prevalence in horses that were extensively managed and not intensively exercised. A recent Vet Times clinical update cited the paper as part of the evolving understanding of equine gastric disease, and industry commentary has similarly highlighted that turnout doesn't always eliminate ulcer risk. (researchgate.net)
While I didn't find substantial independent expert reaction specific to this paper, the broader commentary around the group's earlier Icelandic horse work is consistent: clinicians shouldn't assume breed or pasture access protects against gastric lesions. In prior coverage, lead author Nanna Luthersson said the team would not expect the earlier Icelandic findings to be unique to that breed when considering ESGD risk, a point that gives this newer study relevance beyond Iceland alone. (thehorse.com)
Why it matters: For veterinary professionals, the paper reinforces the need to look beyond the usual high-performance-horse model when assessing gastric disease risk. In practical terms, that means asking more detailed questions about seasonal pasture decline, whether forage is added when grazing drops off, dental status in older horses, and body condition trends across the year. It may also justify a lower threshold for gastroscopy in horses with vague clinical signs, poor performance, weight or condition changes, or recurrent gastrointestinal concerns, even in systems that pet parents perceive as low risk because the horses live outdoors year-round. (researchgate.net)
The paper also has management implications at the herd level. If reduced grass availability without supplemental forage is a major ESGD signal, then preventive planning around seasonal pasture transitions could become a more important part of case discussions. Likewise, the association between dental abnormalities and EGGD supports integrating oral exams more deliberately into gastric disease workups, especially for older horses. Supporting evidence from other literature has linked dental disorders with gastric disease and gastric pH changes, which makes that finding biologically plausible, even if intervention studies are still needed. (researchgate.net)
What to watch: The next step is whether this observational work leads to intervention studies, particularly around supplemental forage during low-grass periods, dental care, and management adjustments by region or herd structure; those are the areas most likely to translate this epidemiology into prevention guidance. (researchgate.net)