What is bilberry?
Bilberry is an herb whose fruit has been used in human herbal medicine for centuries. Bilberry, related to blueberry, has antioxidant properties, and is most commonly taken internally in people to help with disorders of the eyes including macular degeneration (deterioration of part of the retina or back of the eye) and cataract formation. To date, there have been no trials to test the effectiveness of bilberry for the treatment of eye disorders. Bilberry is also believed to improve night vision, but studies have been inconclusive. The ability of bilberry to increase vision may depend on the dose used and the source of the plant.
Bilberry extract may hold promise in treating vascular (blood vessel) tumors in dogs.
Of far more potential interest to veterinarians is relatively new research into bilberry’s effects on circulation. The flavonoids in bilberry have long been known to improve circulation, presumably by reducing capillary fragility. Bilberry has been used in humans to improve retinal blood flow and to treat peripheral circulation disorders such as bruising and varicosities (e.g. varicose veins). More recently, it was found that the flavonoids strongly inhibit the formation of hemangioma (benign tumors), resulting in a reduction of tumor size by about 50 percent in one human study. These results suggest bilberry extract may hold promise in treating vascular (blood vessel) tumors in dogs, such as hemangiosarcoma. An anti-neoplastic (i.e. anti-tumor) effect against other cell types has also been demonstrated, due in part to bilberry’s content of anthocyanins. Anthocyanins are a powerful antioxidant that play a significant role in inhibiting tumor formation due to their ability to reduce free radicals which might otherwise damage DNA and promote tumor formation (see Antioxidants).
Why recommend administration of bilberry to my pet?
In people, bilberry has been used to treat diarrhea, eye problems relating to impaired retinal blood flow, and problems associated with peripheral perfusion (blood flow to the extremities). In pets, it is often prescribed for conditions that may respond to the use of antioxidants. Eye diseases including cataracts and retinal degeneration may respond to bilberry supplementation, but controlled studies are lacking. Bilberry may prove effective in the treatment of hemangiosarcoma (cancer of blood vessels) in dogs.
How much experience is there with the use of bilberry in pets?
Bilberry has been recommended for pets based upon experience in people. Its use in pets is very recent and little information is available about its efficacy.
What species of animals are being treated regularly with bilberry?
Generally, dogs and cats are treated with supplements containing bilberry and other antioxidants.
How much research has been conducted on this supplement?
Both in vitro laboratory testing and research with human subjects have been conducted, but there are no controlled studies in pets.
How successful is bilberry?
Bilberry is unlikely to be effective for progressive retinal atrophy (PRA or deterioration of the blood vessel and nerve-rich back of the eye) in dogs, since the problem does not arise from poor blood flow (instead, PRA creates poor blood flow). While it hasn't been proven yet, bilberry may be of far more benefit for dogs in the treatment of hemangiosarcoma (blood vessel cancer). Bilberry can be expected to benefit any condition that would benefit from antioxidant therapy, given bilberry’s content of potent flavonoids.
How safe is bilberry?
Bilberry is very safe and considered non-toxic. Essentially, it can be considered a food.
Where do I get bilberry and do I need a prescription?
Since supplements are not highly regulated and may not contain the amount of ingredients stated on the label, pet owners should be careful about buying any supplements without knowledge of the manufacturer. Your veterinarian may be able to recommend a preferred brand. A prescription for bilberry is not needed.