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Equine veterinary journal2024; 57(1); 160-168; doi: 10.1111/evj.14056

Equine uveitis: Outcome and adverse effects after one or two intravitreal low-dose gentamicin injections.

Abstract: Uveitis is common in horses, potentially turning chronic (persistent or recurrent) resulting in impaired vision or blindness. All mainstay therapeutics aims at controlling inflammation, but long-term or lifelong treatment is often needed with possibly severe side effects. Therefore, intravitreal injections with low-dose gentamicin (IVGI) have been used in attempt to give a long-lasting result with potentially less side effects. Objective: To retrospectively assess outcome and long-term complications following one or two low-dose IVGI in Swedish horses with chronic uveitis. Methods: Retrospective case series. Methods: Medical records of horses diagnosed with uveitis examined at the Equine Clinic of the University Animal Hospital of Sweden between 2016 and 2021 were reviewed. Inclusion criteria were horses with a diagnosis of chronic uveitis that were treated with 4 mg IVGI. After injection, tapering doses of anti-inflammatory medications were administered. Due to persistence or recurrence of uveitis despite IVGI, some horses received a second injection. A positive outcome was defined as controlled uveitis, despite no or minimal anti-inflammatory medication. Results: 32 eyes (29 horses) were included. Based on clinical evaluation, uveitis was classified as anterior (91%) or panuveitis (9%). 10 eyes were treated with IVGI twice. A positive outcome was observed in 13/32 eyes (41%). Inflammation in 9/32 eyes was controlled after the first, and in 4/10 eyes after the second IVGI treatment. Long-term complications included retinal degeneration in seven eyes, and mature cataracts in five eyes. Enucleations were performed in 14/32 eyes, due to lack of favourable response of IVGI, or due to complications, that is, glaucoma, corneal ulceration, and/or corneal mineralisation. One horse was euthanised due to painful bouts of inflammation in both eyes despite treatment. Conclusions: Small sample size, retrospective design with no control group, no histopathology performed, infrequent sampling for Leptospira and no standardised treatment protocol after the IVGI. Conclusions: In this group of Swedish horses, predominantly diagnosed clinically with anterior uveitis, a positive outcome was observed in 41% of eyes following one or two low-dose IVGI. Retinal degeneration in the visual streak was observed in 22% of eyes, which is a higher proportion of this complication than previously described.
© 2024 The Authors. Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.
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Publication Date: 2024-02-08 PubMed ID: 38329024PubMed Central: PMC11616955DOI: 10.1111/evj.14056Google 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 aims to study the impact of one or two intravitreal injections of low-dose gentamicin (IVGI) in treating chronic uveitis in horses, and explores the long-term complications of this treatment.

Methodology

  • The researchers conducted a retrospective analysis of medical records of Swedish horses treated at the Equine Clinic of the University Animal Hospital between 2016 and 2021.
  • The inclusion criteria for the study were horses diagnosed with chronic uveitis that were treated with a 4-milligram dosage of IVGI. Some horses received a second IVGI injection due to persistence or recurrence of uveitis.
  • A “positive outcome” was defined as controlled uveitis with little to no anti-inflammatory medication.

Results

  • A total of 32 eyes from 29 horses were included in the study. Uveitis was categorized as anterior in 91% of cases and panuveitis in 9% of cases.
  • 10 eyes were treated with two doses of IVGI. A positive outcome was observed in 41% of the treated eyes. 9 of these were controlled after the first dose and 4 after the second dose.
  • Long-term complications included retinal degeneration in seven eyes and mature cataracts in five. Furthermore, 14 eyes had to be enucleated, or removed, due to adverse effects such as glaucoma, corneal ulceration, and corneal mineralisation or lack of response to the IVGI treatment. A single horse had to be euthanised because of painful recurrent bouts of eye inflammation despite undergoing the treatment.

Conclusions

  • The study had several limitations including a small sample size, lack of a control group, absence of histopathology, infrequent Leptospira sampling, and no standardised post-IVGI treatment protocol.
  • Nevertheless, among the group of Swedish horses predominantly diagnosed with anterior uveitis, it was found that 41% of eyes responded positively to one or two low-dose IVGI treatments.
  • Retinal degeneration was observed in 22% of treated eyes, a rate higher than previously described, indicating a possible adverse effect of this treatment mechanism.

Cite This Article

APA
Morén S, Kallberg M, Strom L. (2024). Equine uveitis: Outcome and adverse effects after one or two intravitreal low-dose gentamicin injections. Equine Vet J, 57(1), 160-168. https://doi.org/10.1111/evj.14056

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English
Volume: 57
Issue: 1
Pages: 160-168

Researcher Affiliations

Morén, S
  • Equine Clinic, University Animal Hospital, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Kallberg, M
  • Equine Clinic, University Animal Hospital, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Strom, L
  • Equine Clinic, University Animal Hospital, Swedish University of Agricultural Sciences, Uppsala, Sweden.

MeSH Terms

  • Animals
  • Horses
  • Horse Diseases / drug therapy
  • Uveitis / veterinary
  • Uveitis / drug therapy
  • Retrospective Studies
  • Intravitreal Injections / veterinary
  • Intravitreal Injections / adverse effects
  • Anti-Bacterial Agents / administration & dosage
  • Anti-Bacterial Agents / adverse effects
  • Anti-Bacterial Agents / therapeutic use
  • Female
  • Male
  • Gentamicins / administration & dosage
  • Gentamicins / adverse effects
  • Gentamicins / therapeutic use
  • Treatment Outcome

Conflict of Interest Statement

The authors have no competing interests to declare.

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Citations

This article has been cited 2 times.
  1. Mendes J, Aymée L, Lilenbaum W. A Scoping Review of Antimicrobial Therapy in Leptospira Infections in Domestic Animals. Animals (Basel) 2025 Oct 20;15(20).
    doi: 10.3390/ani15203045pubmed: 41153972google scholar: lookup
  2. Fleischer AB, Amann B, von Toerne C, Degroote RL, Schmalen A, Weißer T, Hauck SM, Deeg CA. Differential Expression of ARG1 and MRC2 in Retinal Müller Glial Cells During Autoimmune Uveitis. Biomolecules 2025 Feb 14;15(2).
    doi: 10.3390/biom15020288pubmed: 40001591google scholar: lookup
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