Silica-containing uroliths in dogs occur very infrequently (≤0.5% of analysed uroliths) in Europe,^1,2 although Schenk et al. (2010)³ observed a peak of 13% in 2009 in Switzerland. The affected dogs were predominately male (88–93%)⁴ and between 7.2 to 8.6^3,4 years old.

A 10-year-old neutered male terrier mongrel (BCS 3/5) with a history of pancreatitis was examined for abdominal pain. During an abdominal ultrasonic examination that revealed no abnormalities of the pancreas but hyperechoic structures in the bladder the dog urinated. The urine sediment was positive for bacteria, erythrocytes and leucocytes but not crystals. Antimicrobial treatment was started. The pancreatic lipase was within the reference range. Two weeks later a urine sample collected by the owner contained numerous struvite crystals; another sample obtained one week later by cystocentesis revealed no crystals and no signs of inflammation and a urine pH of 7.1. The ultrasonographic examination of the bladder a few days afterwards showed multiple uroliths. Twenty stones were removed surgically and the analysis revealed 100% silica.

It is hypothesised that silica uroliths may be related to silica intake by plants or plant by-products with diet or by consumption of soil (>90% silica) secondary of diet-associated pica.⁵ In this case the dog was fed a commercial gastrointestinal lowfat dry diet for 1 year. Additionally, the dog regularly consumed faeces of feral rabbits on its daily walks since more than 2 years. The analysis of a sample of such faeces showed that it contained high amounts of insoluble ash (7% of fresh matter or 12.3% vs. 4% dry matter in pet rabbits). The intake of such faeces together with soil sticking to it might have caused silica uroliths in this case, since no signs of dysuria or abnormal ultrasonographic examinations of the bladder or urinalysis did recur after the dog was kept from consuming rabbit faeces for more than three months.

Disclosures

No disclosures to report.

References

1.  Hesse A, Hoffmann J, Orzekowsky H, Neiger R. Canine cystine urolithiasis: A review of 1760 submissions over 35 years (1979–2013). Can Vet J. 2016; 57(3):277–281.

2.  Roe K, Pratt A, Lulich J, Osborne C, Syme HM. Analysis of 14,008 uroliths from dogs in the UK over a 10-year period. J Small Anim Pract. 2012;53:634–640.

3.  Schenk F, Rothenanger E, Reusch C, Gerber B. Silica-containing uroliths in dogs from Switzerland: A remarkable increase in frequency after 2006. In: Proceedings from ECVIM-CA Congress; September 9–11, 2010: 303; Toulouse, France.

4.  Hesse A, Neiger R. Harnsteine bei Kleintieren. Stuttgart, Germany: Enke; 2008.

5.  Osborne CA, Jacob F, Lulich JP, et al. Canine silica urolithiasis. Risk factors, detection, treatment, and prevention. Vet Clin North Am Small Anim Pract. 1999;29(1):213–230.