The Journal of Veterinary Medical Science · 10 authors, 3 centres
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Oral 5-aminolevulinic acid combined with sodium ferrous citrate (5-ALA/SFC) at 3/1.92 mg/kg significantly reduced protein and PGE2 concentrations in the aqueous humor after anterior chamber paracentesis in beagle dogs, indicating prevention of blood–aqueous barrier breakdown. The effect was comparable to carprofen, a standard NSAID. This suggests 5-ALA/SFC may be a potential adjunctive therapy for uveitis in dogs with fewer side effects.
**Background:** The blood–aqueous barrier (BAB) of the anterior uvea prevents entry of plasma proteins and cells into the aqueous humor (AH). BAB breakdown occurs after surgical trauma (e.g., cataract surgery) or experimental procedures like anterior chamber paracentesis (ACP), leading to anterior uveitis. Prostaglandin E2 (PGE2) is a key mediator in BAB breakdown. Current treatments (corticosteroids, NSAIDs) have side effects, so safer alternatives are needed. 5-aminolevulinic acid (5-ALA) combined with sodium ferrous citrate (5-ALA/SFC) has shown anti-inflammatory effects in rat uveitis models, but its effects in dogs were unknown.
**Methods:** Twenty healthy beagle dogs were randomly divided into four groups (n=5 each): control, low-dose 5-ALA/SFC (1/0.64 mg/kg), high-dose 5-ALA/SFC (3/1.92 mg/kg), and carprofen (4 mg/kg). Treatments were given orally once daily for 7 days before ACP. ACP was performed on one eye under sedation, and AH samples were collected before (first) and 60 minutes after (second) paracentesis. Protein concentration was measured using a bicinchoninic acid assay, and PGE2 concentration was measured using an ELISA kit. Statistical analyses included paired t-tests and one-way ANOVA with Tukey post-hoc tests.
**Key Results:** In all groups, protein and PGE2 concentrations in the second AH sample were significantly increased compared to the first, confirming BAB breakdown. For protein: control (1,554.9 ± 219.4 mg/dL), low-dose 5-ALA/SFC (1,369.1 ± 278.4 mg/dL, not significantly different from control), high-dose 5-ALA/SFC (1,036.1 ± 295.4 mg/dL, ~39% reduction vs control, P=0.023), carprofen (1,071.5 ± 198.5 mg/dL, ~31% reduction vs control, P=0.035). No significant difference between high-dose 5-ALA/SFC and carprofen. For PGE2: control (55.05 ± 22.09 ng/dL), low-dose 5-ALA/SFC (42.32 ± 4.83 ng/dL, not significant), high-dose 5-ALA/SFC (26.84 ± 7.64 ng/dL, 62.6% reduction vs control, P=0.026), carprofen (28.54 ± 10.91 ng/dL, 58.2% reduction vs control, P=0.017). No significant difference between high-dose 5-ALA/SFC and carprofen.
**Clinical Implications:** This study demonstrates that oral 5-ALA/SFC at 3/1.92 mg/kg effectively prevents BAB breakdown in a canine ACP model, with efficacy similar to carprofen. The reduction in PGE2 suggests an anti-inflammatory mechanism. 5-ALA/SFC may offer a safer alternative or adjunctive therapy for uveitis in dogs, avoiding long-term side effects of steroids and NSAIDs. Limitations include unknown metabolic pathway in dogs, lack of assessment of other cytokines, and the model not fully replicating clinical uveitis. Further studies on safety, toxicity, and mechanism are needed.