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Measurement of tear production and establishment of reference values in guinea pigs (Cavia porcellus) using a modified Schirmer tear test
  1. Anna Linda Nogradi1,
  2. Zsolt Szentgáli2,
  3. Márton Battay1,
  4. Iain Cope3,
  5. János Gál1 and
  6. Tibor Németh2
  1. 1 Department of Exotic Animal and Wildlife Medicine, University of Veterinary Medicine, Budapest, Hungary
  2. 2 Department and Clinic of Surgery and Ophthalmology, University of Veterinary Medicine, Budapest, Hungary
  3. 3 Studland Retail Park, Newmarket Vets4Pets, Inside Pets at Home, Newmarket, UK
  1. Correspondence to Anna Linda Nogradi, Department of Exotic Animal and Wildlife Medicine, University of Veterinary Medicine, Budapest, 1078 Budapest, Hungary; anna.nogradi{at}


Background Past studies have shown that 5-mm Schirmer tear tests (STTs) are difficult to interpret in guinea pigs. Modified 2.5-mm STT strips are more adequate for measuring the small volume of tear production in these animals. The aim of this study was to establish reference values for the modified 2.5-mm STT strips.

Methods Modified STT measurements were performed in random order in both eyes of 50 guinea pig patients. The wetting of the strip was noted at 30 seconds and at 1 minute.

Results The mean±sd STT values for both eyes were 7.58±3.19 mm at 30 seconds and 10.42±3.92 mm at 60 seconds. The median was 8 mm at 30 seconds and 10 mm at 60 seconds for both eyes. Animals under one year of age had lower STT values. STT values at 30 and 60 seconds can both be used. Both eyes should be measured when possible.

Conclusion The authors recommend values above 8 mm at 30 seconds and 10 mm at 60 seconds to be considered normal when using a 2.5-mm STT strip. There are ambiguous areas at 5–8 mm and 6–10 mm. If in these ranges the results should be combined with clinical signs and judgement.

  • guinea pig
  • cavia porcellus
  • ocular
  • tear production
  • schirmer tear test
  • modified schirmer tear test
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  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Ethics approval The study fulfils the Hungarian animal welfare laws and legislations, and the authors had the owners’ consent before STT measurements.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement All data relevant to the study are included in the article.

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