Bernie Vaatstra
Clinical findings
A 13-year-old, spayed female Lhasa Apso presented at an after-hours veterinary clinic for acute gastric dilatation. Prior history included several years of upper gastrointestinal signs including intermittent vomiting and inappetence. Clinical signs improved on institution of treatment with 10mg omeprazole SID in 2023, and remained stable until October 2024, when the dog presented with moderate gastric bloating which resolved after treatment with maropitant citrate 1mg/kg. The dog then presented acutely with marked gastric dilatation in late January, 2025.
On admission to the veterinary hospital, the stomach was decompressed but bloated again the following day. Based on imaging suggestive of a gastric foreign body, exploratory laparotomy was undertaken. Gravel was removed from the stomach, but no foreign bodies large enough to explain pyloric obstruction. There was no evidence of pyloric hypertrophy or neoplasia and there were no significant gross findings in the remainder of the gastrointestinal tract. Biopsies were collected from the stomach and duodenum to look for potential underlying causes.
The dog recovered after surgery and remained stable at the time of follow-up 3 weeks later.
Pathology
Histological findings included oedema and haemorrhage of the stomach wall attributed to trauma caused by gastric distention and/or foreign material (Figure 1). There was mild lymphoplasmacytic and eosinophilic inflammation which was considered equivocal for underlying inflammatory bowel disease. In addition, there were numerous distinctive large coccoid bacteria occurring in small clusters (2-8 cells) located within the mucus layer (Figure 2). The organisms were Gram and PAS positive (Figure 3). Morphologically, the bacteria resembled Sarcina spp. (Sarcina ventriculi, Clostridium ventriculi).
Discussion
Sarcina-like bacteria are very rarely seen in canine gastric biopsies. One report details a possible association between Sarcina ventriculi and gastric dilatation in two dogs (Vatn et al. 2000). More commonly, Sarcina spp. are observed in abomasal biopsies from calves and lambs dying of acute abomasal bloat (Edwards et al. 2008). In humans, Sarcina ventriculi is associated with rare cases of delayed gastric emptying, gastric distension, dyspepsia, ulceration and perforation, with a mortality rate of 14%. Conditions that promote overgrowth include diabetic gastroparesis, pyloric stenosis, and gastric surgery (Tartaglia et al. 2022).
Proton pump inhibitors (PPIs) such as omeprazole are widely used in both human and veterinary medicine and considered safe and effective for treatment of a range of upper GI disorders (notably, GERD). However, long term use does increase the risk of adverse side effects. Evidence shows that PPIs alter the GI microbiome and may increase the risk of infections such as Clostridium difficile. They may also increase the risk of hyperplastic and neoplastic gastric disorders due to hypergastrinemia. Similar to the situation in humans, omeprazole use is known to alter GI bacterial microbiota in dogs (Garcia-Mazcorro et al. 2012).
In the present case, gastric biopsy revealed a possible opportunistic role for Sarcina spp. in gastric dilatation in a dog. While a clear cause cannot be concluded, long term use of omeprazole along with underlying IBD, gastric foreign body, and stomach surgery are factors that could potentially promote gastrointestinal dysbiosis and overgrowth of gas-producing Sarcina spp.
Acknowledgements to Tom Taylor from Estuary Veterinary Clinic for this interesting case.
References
Edwards GT, Woodger NG, Barlow AM, Bell SJ, Harwood DG, Otter A, Wight AR. Sarcina-like bacteria associated with bloat in young lambs and calves. Vet Rec. 163:391-3, 2008.
Garcia-Mazcorro JF, Suchodolski JS, Jones KR, Clark-Price SC, Dowd SE, Minamoto Y, Markel M, Steiner JM, Dossin O. Effect of the proton pump inhibitor omeprazole on the gastrointestinal bacterial microbiota of healthy dogs. FEMS Microbiol Ecol. 80:624-36, 2012.
Tartaglia D, Coccolini F, Mazzoni A, Strambi S, Cicuttin E, Cremonini C, Taddei G, Puglisi AG, Ugolini C, Di Stefano I, Basolo F, Chiarugi M. Sarcina ventriculi infection: a rare but fearsome event. A Systematic Review of the Literature. Int J Infect Dis. 115:48-61, 2022.
Vatn S, Gunnes G, Nybø K, Juul HM. Possible involvement of Sarcina ventriculi in canine and equine acute gastric dilatation. Acta Vet Scand. 41:333-7, 2000.
Cover image: Sticker-mule-Unsplash