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Veterinary ophthalmology2020; 24(1); 20-27; doi: 10.1111/vop.12822

Serum albumin and total protein concentration in the tear film of horses with healthy or diseased eyes.

Abstract: To determine total protein content (TPC) and serum albumin levels in the tears of horses with healthy or diseased eyes. Methods: Forty-two horses with healthy eyes and 11 horses with unilateral (n = 10) or bilateral (n = 1) ocular disease. Methods: Each eye underwent an ophthalmic examination including detailed conjunctivitis scoring and tear collection with Schirmer strips. TPC and serum albumin levels were quantified in tear samples and compared among healthy eyes, affected eyes, and contralateral unaffected eyes. The impact of the following variables on lacrimal protein levels were assessed: age, breed, and sex (healthy eyes), as well as conjunctivitis score (diseased eyes). Results: Lacrimal TPC ranged from 7.0 to 19.5 mg/mL in healthy eyes, while serum albumin ranged from 71.1 to 711.3 µg/mL (~1.6% of TPC) and was higher in tears of aged and female horses (P ≤ .033). Eyes with ocular disease had significantly greater (P ≤ .001) serum albumin in tears (median 679.6 µg/mL) compared to contralateral unaffected eyes (130.0 µg/mL) and eyes of the reference population (200.7 µg/mL). However, lacrimal TPC did not differ significantly among the 3 groups. Scoring of palpebral conjunctival hyperemia trended toward a positive association with serum albumin in tears (r = 0.49, P = .062). Conclusions: The protein profile in equine tears differs in health and disease. Serum albumin in tears increases with ocular disease and, similar to other species, might serve as a biomarker for ocular insult in horses. Future studies could investigate the protein levels in horses with specific ocular conditions and help determine the biological importance of albumin on the equine ocular surface.
© 2020 American College of Veterinary Ophthalmologists.
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Publication Date: 2020-09-12 PubMed ID: 32920954DOI: 10.1111/vop.12822Google Scholar: Lookup
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  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research paper aims to compare the levels of total protein content (TPC) and serum albumin in the tears of healthy horses and those with ocular diseases. The results reveal that serum albumin in tears increases with eye disease, which might act as a biomarker for ocular insult in horses.

Methodology

  • The study involved 42 horses with healthy eyes and 11 horses with either a unilateral (10 cases) or bilateral (1 case) eye disease.
  • Each eye underwent an extensive ophthalmic examination that included a detailed score of conjunctivitis and collection of tears with a Schirmer strip which is a standard method to test tear production.
  • The levels of total protein content (TPC) and serum albumin were quantified in the tear samples.
  • The investigators then compared these protein levels among healthily unaffected eyes, affected eyes, and the unaffected eyes of the horses with a diseased eye.
  • Variables that can potentially affect lacrimal protein levels, such as age, breed, and sex, were assessed for healthy eyes. In addition, a scoring of conjunctivitis was measured for diseased eyes.

Results

  • The total protein content in the tears of healthy eyes ranged between 7.0 and 19.5 mg/mL. The serum albumin levels in these tears varied from 71.1 to 711.3 μg/ml, which was approximately 1.6% of the TPC. Incidentally, older and female horses had slightly higher serum albumin levels.
  • Horses with ocular disease had a significantly higher amount of serum albumin in their tears compared to the unaffected eye and to the eyes of the control group.
  • However, there was no significant difference in TPC among healthy eyes, affected eyes, and contralateral unaffected eyes. This means that ocular disease did not significantly affect the total protein content in equine tears.
  • The score for palpebral conjunctival hyperemia (excessive blood flow to the conjunctiva, the membrane that covers the front of the eye) showed a trend towards positive association with serum albumin levels in the tears, meaning there could be a potential link between them.

Conclusion

  • The protein profile in equine tears changes between healthy and diseased states, notably with a significant increase in serum albumin levels in cases of ocular disease. This suggests that serum albumin could potentially serve as a biomarker for ocular diseases in horses.
  • The study suggests the need for future research to explore protein levels in horses with specific ocular conditions which can help to ascertain the biological importance of albumin on the equine ocular surface.

Cite This Article

APA
Terhaar HM, Allbaugh RA, Mochel JP, Sebbag L. (2020). Serum albumin and total protein concentration in the tear film of horses with healthy or diseased eyes. Vet Ophthalmol, 24(1), 20-27. https://doi.org/10.1111/vop.12822

Publication

Veterinary ophthalmology
ISSN: 1463-5224
NlmUniqueID: 100887377
Country: England
Language: English
Volume: 24
Issue: 1
Pages: 20-27

Researcher Affiliations

Terhaar, Hannah M
  • Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, USA.
Allbaugh, Rachel A
  • Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, USA.
Mochel, Jonathan P
  • Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, USA.
Sebbag, Lionel
  • Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, USA.
  • Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, USA.

MeSH Terms

  • Animals
  • Eye Diseases / blood
  • Eye Diseases / metabolism
  • Eye Proteins / metabolism
  • Female
  • Horse Diseases / blood
  • Horse Diseases / metabolism
  • Horses / blood
  • Horses / metabolism
  • Male
  • Reference Values
  • Serum Albumin / metabolism
  • Tears / metabolism

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Citations

This article has been cited 9 times.
  1. Stolle LM, Oltmanns H, Meißner J, Heun F, Schieder AK, Wolff HT, Ohnesorge B, Busse C. Polyhexanide, Povidone-Iodine, and Hypochlorous Acid Show High In Vitro Antimicrobial Efficacy Against Pathogens Commonly Associated With Equine Infectious Keratitis. Vet Ophthalmol 2026 Jan;29(1):e70141.
    doi: 10.1111/vop.70141pubmed: 41552904google scholar: lookup
  2. Šoša I. From Tears to Toxins: Mapping Antibiotic Passage Through the Eye-Liver Axis. Antibiotics (Basel) 2025 Oct 24;14(11).
    doi: 10.3390/antibiotics14111069pubmed: 41301564google scholar: lookup
  3. Heun F, Meißner J, Schieder AK, Ohnesorge B, Busse C. Pantoea agglomerans in Equine Ulcerative Keratitis: Prevalence and Comparative Efficacy of Four Topical Antiseptics. Vet Ophthalmol 2026 Jan;29(1):e70044.
    doi: 10.1111/vop.70044pubmed: 40557447google scholar: lookup
  4. Tan Y, De La Toba E, Rubakhin SS, Labriola LT, Canfield C, Pan D, Sweedler JV. NanoLC-timsTOF-Assisted Analysis of Glycated Albumin in Diabetes-Affected Plasma and Tears. J Am Soc Mass Spectrom 2024 Jan 3;35(1):106-113.
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  6. Ritchoo S, Havanapan PO, Phungthanom N, Rucksaken R, Muikaew R, Sussadee M. Analysis and comparison of tear protein profiles in dogs using different tear collection methods. BMC Vet Res 2022 Dec 21;18(1):442.
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