Update (July 5, 2026): Injectable Platelet-Rich Plasma With Oral Omega-3 for Canine Keratoconjunctivitis Sicca (dos Santos Villa 2025 RCT)

Bottom line

• A 2025 randomized trial (22 dogs, 44 eyes, bilateral KCS) tested subconjunctival injectable homologous platelet-rich plasma (HPRP), alone versus HPRP plus oral omega-3, over 6 months alongside topical lubricants. [1]
• Both arms significantly raised STT-1 from baseline with no intergroup difference (p > 0.05), so omega-3 did not add to aqueous tear production. [1]
• The combination arm produced significantly higher TBUT from month 3 onward (p < 0.05) — a tear-film-stability signal consistent with omega-3's known lipid-layer effect. [1][3]
• The combination also drove faster ulcer resolution, greater conjunctival goblet-cell recovery, and larger drops in lacrimal-gland lymphocytes/neutrophils on cytology and histopathology. [1]
• This is a small, single-center, brachycephalic-heavy trial with no follow-up past 6 months — hypothesis-generating, not a reason to displace ciclosporin/tacrolimus as first-line. [1]

Clinical facts

Canine keratoconjunctivitis sicca (KCS) is most often immune-mediated destruction of the lacrimal and third-eyelid (nictitans) glands, producing a quantitative aqueous-deficient dry eye plus a qualitative tear-film component. Standard of care remains a topical calcineurin inhibitor — ciclosporin or tacrolimus — to restore tear production, layered with tear substitutes; injectable platelet-rich plasma has been explored as an adjuvant or lower-cost option that delivers autologous/homologous growth factors to the ocular surface and glands. [1][2]

The 2025 study under review is a primary randomized trial that asks a narrower question: does adding oral omega-3 to injectable HPRP improve outcomes beyond HPRP alone? Its headline is a dissociation clinicians should note — omega-3 did not further raise Schirmer values, but it did improve tear-film stability (TBUT) and several inflammatory/epithelial endpoints. [1]

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What the evidence shows

Anchor — dos Santos Villa et al., Veterinary World 2025. [1] Twenty-two dogs (44 eyes) with bilateral KCS (enrolled at STT-1 < 15 mm/min and/or TBUT < 20 s) were randomized to HPRP alone (11 dogs) or HPRP + oral omega-3 (11 dogs). HPRP was given by subconjunctival injection, 0.3 mL per eye (0.1 mL each into the third-eyelid gland, inferior conjunctiva, and superior conjunctiva), up to three monthly sessions titrated to response; both groups used sodium hyaluronate/carmellose lubricant twice daily for 6 months. The omega-3 arm received 500 mg/10 kg/day (dogs ≤ 10 kg) or 1000 mg/day (> 10 kg).

Results:

• STT-1 rose significantly from baseline in both arms (p < 0.05) with no intergroup difference (p > 0.05) — omega-3 added nothing to aqueous production. [1]
• TBUT was significantly higher in the combination arm from month 3 through month 6 (p < 0.05), the study's central finding. [1]
• Corneal ulcers resolved faster with the combination (absent by month 5 vs month 6 for HPRP alone); pigmentation, neovascularization, discharge, and conjunctival hyperemia all improved, generally earlier in the combination arm. [1]
• Cytology and conjunctival histopathology showed greater reductions in lymphocytes and neutrophils and a larger rise in goblet cells in the combination arm (p < 0.05). [1]
• Fewer injections were needed in the combination arm: 27% needed only one session versus 9% for HPRP alone. [1]
• Safety: two dogs (one per arm, ~4.5%) had transient eyelid edema that resolved with topical diclofenac; no withdrawals. [1]

Supporting — prior injectable-HPRP RCT (same group), Veterinary World 2023. [2] In an earlier 6-month randomized trial (11 KCS dogs per arm) comparing topical 0.03% tacrolimus with the identical subconjunctival HPRP protocol, injectable HPRP significantly improved STT-1 and TBUT from baseline and was judged "safe and feasible… a cheaper alternative or adjuvant," though tacrolimus was more efficient for tear production and goblet-cell proliferation. This establishes injectable HPRP as a plausible KCS adjuvant while keeping calcineurin inhibitors ahead on the core aqueous-deficiency endpoint. [2]

Supporting — omega-3 mechanism in dry eye. [3] A double-blind human RCT (518 eyes) of oral omega-3 (EPA 325 mg/DHA 175 mg twice daily, 3 months) found omega-3 preferentially improved tear-film stability over tear production — mean TBUT gain 2.54 s vs 0.13 s for placebo (p < 0.001), with only a marginal Schirmer change — and the effect was largest in meibomian-gland/lipid-layer disease. That STT-vs-TBUT dissociation mirrors exactly what the canine trial reports, giving the animal finding a coherent lipid-layer rationale. [3]

How this fits clinical practice

The signal is directionally consistent and biologically sensible: omega-3 acts on the lipid/qualitative side of the tear film, so it is unsurprising that it lifts TBUT and ocular-surface inflammation without changing Schirmer output, which reflects the aqueous deficit that PRP and calcineurin inhibitors target. For a KCS patient already on a topical immunomodulator with persistent surface instability, epithelial disease, or breakthrough ulceration, an oral omega-3 adjunct is low-risk and mechanistically defensible. [1][3]

Temper enthusiasm with the study's limits. It is a single-center trial of 22 mostly brachycephalic dogs, unblinded to intervention type, without a lubricant-only or PRP-free omega-3 control, and with no data beyond 6 months; homologous PRP preparation is not standardized across practices, and subconjunctival injection into the nictitans gland is a technique-dependent, in-clinic procedure. Nothing here displaces ciclosporin or tacrolimus as first-line for canine KCS — the combination is best read as a potential adjuvant for tear-film stability and surface inflammation, pending larger, longer, better-controlled confirmation. [1][2]

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This evidence brief is for licensed veterinary professionals and summarizes published research; it is not a treatment protocol and does not replace clinical judgment or product labeling.

References

1. dos Santos Villa W, Passareli JVGC, Estanho GJG, Gomes MACN, Nai GA, Santarém CL, Andrade SF. Injectable homologous platelet-rich plasma, alone or in combination with oral omega-3 supplementation, for treating keratoconjunctivitis sicca in dogs. Veterinary World. 2025;18(5):1262-1273. doi:10.14202/vetworld.2025.1262-1273. https://pmc.ncbi.nlm.nih.gov/articles/PMC12205238/
2. Estanho GJG, et al. Comparison of topical 0.03% tacrolimus and homologous injectable platelet-rich plasma in the treatment of keratoconjunctivitis sicca in dogs. Veterinary World. 2023;16(1):134-143. doi:10.14202/vetworld.2023.134-143. https://pmc.ncbi.nlm.nih.gov/articles/PMC9967714/
3. Bhargava R, Kumar P, Kumar M, Mehra N, Mishra A. A randomized controlled trial of omega-3 fatty acids in dry eye syndrome. International Journal of Ophthalmology. 2013;6(6):811-816. doi:10.3980/j.issn.2222-3959.2013.06.13. https://pmc.ncbi.nlm.nih.gov/articles/PMC3874521/

Changelog

• 2026-07-05: First published.