Forums

Guidance, support and wisdom to benefit and maximize the life and longevity of animals.

VetVine CE

Posted On Jun 24, 2025

Updated On Jul 08, 2025

Oxidative Stress, Antioxidants, And Eye Health

Ophthalmology

Veterinarians are frequently asked about the value of giving supplements as part of general wellness or care of pets with disease. This comes as no surprise given the boom in premium products available to consumers and the belief that organic or natural foods and supplements are safer and better for pets. In fact, the pet supplement market alone was predicted to grow from $2.27 billion in 2024 to $2.44 billion in 2025.[1]

The evidence supporting the benefit of supplements is building and studies have shown the efficacy of many including omega-3 fatty acids, probiotics, and antioxidants in benefiting patients with a variety of diseases (e.g. kidney, gastrointestinal, dermatologic, etc.).

Oxidative stress is a natural biological phenomenon that occurs in all living animals, including pets. While oxidation is a normal part of cellular metabolism, excessive oxidant accumulation—especially without adequate antioxidant defense—can damage tissues and organs. This imbalance is a known contributor to a range of diseases including diabetes mellitus, cardiovascular disease, neurodegenerative conditions, cataracts, and others.

Oxidants, or reactive oxygen species (ROS), are molecules generated both within the body and as a consequence to exposure to external sources like pollution, UV light, tobacco smoke, and diet. While the body has its own defense systems—endogenous antioxidants such as glutathione and superoxide dismutase (SOD)—these systems can become overwhelmed. When the balance shifts in favor of oxidants, oxidative stress ensues, leading to cellular damage and disease.

Antioxidants and Eye Health

In the eye, glutathione is the primary antioxidant within the lens, protecting it from oxidative damage. With age, UV exposure, or inflammation, glutathione levels decline, resulting in the generation of free radicals that damage lens cells. This damage can lead to the development of cataracts, where the lens becomes cloudy and impairs vision.

Efforts to counteract oxidative stress and delay cataract formation have included the use of antioxidant therapies, both synthetic and plant-derived. One plant of interest in this area is Sea Buckthorn (Hippophae rhamnoides).

Sea buckthorn is a hardy shrub native to parts of Europe and Asia, traditionally used for a variety of health concerns ranging from infections to cardiovascular disease. Its leaves, fruits, and seeds are packed with nutrients, including:

  • Vitamin C and E

  • Flavonoids (notably quercetin and catechins)

  • Carotenoids

  • Plant sterols and tocopherols

These constituents have been shown to have potent antioxidant, anti-inflammatory, immunomodulatory, and antimicrobial properties.

Several years ago an in vitro study[2] explored the anti-cataract potential of sea buckthorn leaf extract using lenses from goat eyes. The researchers extracted phytochemicals from sea buckthorn leaves, divided the lenses into 7 groups (inducing oxidative stress in some using hydrogen peroxide), then treated different groups with varying concentrations of sea buckthorn extract (100–1,000 µg/mL), and compared results with lenses treated with vitamin E, a known antioxidant.

Key Findings:

  • Sea buckthorn leaf extract significantly restored glutathione and SOD levels in oxidatively stressed lenses, especially at 500–1,000 µg/mL.

  • Malonaldehyde (MDA), a marker of oxidative damage, was significantly reduced in treated groups.

  • Though not quite as potent as vitamin E, sea buckthorn performed nearly as well, suggesting its strong antioxidant potential.

These results indicate that the aqueous extract of sea buckthorn may help protect against cataract formation by neutralizing oxidative stress in the lens.

Other Uses and Considerations

Sea buckthorn's potential ocular benefits also include protection against light-induced retinal damage and improving symptoms of dry eye. It also has promise in treating gastrointestinal ulcers in both dogs[3] and horses[4]. A 2013 study in dogs demonstrated faster ulcer healing when treated with sea buckthorn oil compared to conventional drugs. In horses, a similar benefit was observed.

Commercial Antioxidant Products for Eye Health

Several antioxidant supplements and topicals are on the market, though clinical evidence remains limited:

  • Ocu-GLOTM: An oral supplement for dogs that includes grape seed extract, vitamins, omega-3s, and more. One study suggested it may delay cataract onset in diabetic dogs, but results were not definitive.

  • Optixcare Eye Health (EH): A topical antioxidant preparation was shown in a rat model to outperform oral Ocu-GLOTM in reducing oxidative stress in the eye.

Limitations and Safety Concerns

While promising, sea buckthorn research is still ongoing. The study discussed here was in vitro and conducted on goat lenses. The appropriate oral dose for dogs to achieve therapeutic effects in the eye remains unknown. Although no adverse effects were seen in past GI studies in dogs, more safety data is needed, especially for long-term use or concurrent therapies like chemotherapy or anticoagulants.

Conclusion

Oxidative stress plays a central role in cataract development and other health concerns in pets. Antioxidant therapy, especially from natural sources like sea buckthorn, offers an exciting avenue for prevention. Though more in vivo studies are needed, past evidence suggests that sea buckthorn extract may hold promise as a protective agent against oxidative damage in the eye. Pet owners and veterinarians interested in antioxidant therapy (or any supplement) should remain informed about ongoing research and exercise caution when considering unregulated nutraceuticals.

[1] Pet Supplements Global Market Report 2025. The Business Research Company

[2] Phytochemical characterization and evaluation of anticataract potential of seabuckthorn leaf extract. Vet Ophthalmol. 2016 Mar;19(2):144-8. doi:10.1111/vop.12271

[3] Efficacy of Seabuckthorn (Hippophae rhamnoides) Oil vis-a-vis Other Standard Drugs for Management of Gastric Ulceration and Erosions in Dogs. Vet Med Int. 2013;2013:176848. doi: 10.1155/2013/176848

[4] Effect of Sea Buckthorn Berries and Pulp in a Liquid Emulsion on Gastric Ulcer Scores and Gastric Juice pH in Horses. J Vet Int Med. 2012 Sept;26(5):1186-1191. doi: 10.1111/j.1939-1676.2012.00975.x