Tear Film Osmolarity in Horses With Bacterial Conjunctivitis.
Abstract: Conjunctivitis is an inflammation of the conjunctiva caused by infectious or non-infectious factors. Infectious conjunctivitis comes in two forms: viral and bacterial. Bacterial conjunctivitis is commonly caused by organisms such as Staphylococcus and Streptococcus, with the severity of the disease influenced by the specific bacterial species involved. Because both viral and bacterial conjunctivitis are highly contagious, preventive measures are essential to reduce transmission-especially to the unaffected eye. Objective: To evaluate the tear film osmolality in horses with bacterial conjunctivitis. Methods: A total of 40 healthy horses and those with conjunctivitis were included in the study. Tear samples were collected from both eyes with microcapillary tubes three times at 5-min intervals. The tear samples for each horse were pooled, and the osmolality and electrolyte concentrations were measured. The mean (SD) was calculated for each variable to establish preliminary guidelines for tear film osmolality and electrolyte composition in healthy horses. Results: The mean (SD) tear film osmolality was 283.51 (9.33) mmol/kg, and the mean (SD) sodium, potassium, magnesium and calcium concentrations were 134.75 (10), 16.3 (5.77), 3.48 (1.97) and 1.06 (0.42) mmol/L, respectively. The sodium concentration in the tear film was similar to that in serum, whereas the potassium concentration in the tear film was approximately 4.75 times that of serum. Conclusions: Measuring tear-film osmolality offers a non-invasive, easy and practical approach to gaining valuable insights into baseline conditions and potential changes in ocular diseases. However, its true clinical utility requires integration with other ocular parameters and further controlled studies in horses suffering from conjunctivitis. The development of such tools could lead to more accurate diagnoses and more comprehensive treatment strategies.
© 2025 The Author(s). Veterinary Medicine and Science published by John Wiley & Sons Ltd.
Publication Date: 2025-11-17 PubMed ID: 41243880PubMed Central: PMC12620991DOI: 10.1002/vms3.70677Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
Cite This Article
APA
Saberinia A, Ozmaei S, Anoushepour A.
(2025).
Tear Film Osmolarity in Horses With Bacterial Conjunctivitis.
Vet Med Sci, 11(6), e70677.
https://doi.org/10.1002/vms3.70677 Publication
Researcher Affiliations
- Department of Clinical Sciences, Science and Research Branch, Islamic Azad University, Tehran, Iran.
- Department of Clinical Sciences, Science and Research Branch, Islamic Azad University, Tehran, Iran.
- Department of Veterinary Clinical Sciences, Ka.C., Islamic Azad University, Karaj, Iran.
MeSH Terms
- Animals
- Horses
- Tears / chemistry
- Tears / physiology
- Horse Diseases / microbiology
- Horse Diseases / physiopathology
- Osmolar Concentration
- Conjunctivitis, Bacterial / veterinary
- Conjunctivitis, Bacterial / microbiology
- Conjunctivitis, Bacterial / physiopathology
- Male
- Female
Conflict of Interest Statement
The authors declare no conflicts of interest.
References
This article includes 12 references
- Almutleb, E. S. , Almutairi M. S., El‐Hiti G. A., et al. 2025. “Assessment of Tear Film in Arabian Horses With a Portable Device Compared to Human's Healthy Eyes.” Egyptian Journal of Veterinary Sciences 56, no. 13: 51–58.
- Best, L. J. , Hendrix D. V., and Ward D. A.. 2015. “Tear Film Osmolality and Electrolyte Composition in Healthy Horses.” American Journal of Veterinary Research 76, no. 12: 1066–1069. 10.2460/ajvr.76.12.1066.
- Bron, A. J. , de Paiva C. S., Chauhan S. K., et al. 2017. “TFOS DEWS II Pathophysiology Report.” Ocular Surface 15, no. 3: 438–510.
- Bron, A. J. , and Willshire C.. 2021. “Tear Osmolarity in the Diagnosis of Systemic Dehydration and Dry Eye Disease.” Diagnostics 11, no. 3: 387. 10.3390/diagnostics11030387.
- Brooks, D. E. 2010. “Equine Conjunctival Diseases: A Commentary.” Equine Veterinary Education 22, no. 8: 382–386.
- Davis, K. , and Townsend W.. 2011. “Tear‐Film Osmolarity in Normal Cats and Cats With Conjunctivitis.” Veterinary Ophthalmology 14, no. S1: 54–59. 10.1111/j.1463-5224.2011.00916.x.
- Gilbard, J. P. , and Farris R. L.. 1979. “Tear Osmolarity and Ocular Surface Disease in Keratoconjunctivitis Sicca.” Archives of Ophthalmology 97, no. 9: 1642–1646.
- Lamkin, I. D. , Zimmerman K. L., Smith Fleming K. M., and Martins B. C.. 2020. “Osmolarity of Basal and Reflex Tears of Normal Dogs.” Veterinary Ophthalmology 23, no. 4: 747–753. 10.1111/vop.12798.
- Maggs, D. J. , Miller P. E., Ofri R., et al. 2017. Slatter's Fundamentals of Veterinary Ophthalmology. Saunders.
- Potvin, R. , Makari S., and Rapuano C. J.. 2015. “Tear Film Osmolarity and Dry Eye Disease: A Review of the Literature.” Clinical Ophthalmology 9: 2039–2047. 10.2147/OPTH.S95242.
- Sebbag, L. , Park S. A., Kass P. H., et al. 2016. “Assessment of Tear Film Osmolarity Using the TearLab™ Osmometer in Normal Dogs and Dogs With Keratoconjunctivitis Sicca.” Veterinary Ophthalmology 20, no. 4: 357–364. 10.1111/vop.12436.
- Tashbayev, B. , Utheim T. P., Utheim Ø. A., et al. 2020. “Utility of Tear Osmolarity Measurement in Diagnosis of Dry Eye Disease.” Scientific Reports 10: 5542. 10.1038/s41598-020-62583-x.
Citations
This article has been cited 0 times.Use Nutrition Calculator
Check if your horse's diet meets their nutrition requirements with our easy-to-use tool Check your horse's diet with our easy-to-use tool
Talk to a Nutritionist
Discuss your horse's feeding plan with our experts over a free phone consultation Discuss your horse's diet over a phone consultation
Submit Diet Evaluation
Get a customized feeding plan for your horse formulated by our equine nutritionists Get a custom feeding plan formulated by our nutritionists
