Bilberry

What is bilberry?

Bilberry, also known as the European blueberry, whortleberry, or huckleberry, is a berry related to the blueberry. Bilberry has a high concentration of anthocyanins, which are antioxidants.

Bilberry is used as a dietary supplement to treat eye problems, but it has also been used as an antioxidant to treat cardiovascular conditions, diarrhea, urinary tract infections, diabetes, and other conditions in dogs, cats, and other animals.

New research has suggested that flavonoids found in bilberry may inhibit the formation of hemangiomas (a benign tumor). These results suggest bilberry extract may hold promise in treating cancerous 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.

The U.S. Food and Drug Administration (FDA) does not review non-drug health products (e.g., herbals, nutraceuticals, shampoos, and other supplements) for safety or effectiveness before they are sold to the public. Manufacturers of non-drug health products must ensure their products are safe and labeled accurately. 

The FDA requires that these non-pharmaceuticals contain a disclaimer that says, “This product is not intended to diagnose, treat, cure or prevent any disease.” Health Canada licenses “veterinary health products” after reviewing safety, efficacy, and manufacturing information provided by the manufacturer. These products are not tested by Health Canada.

Your veterinarian is the best source of information about the safety of non-drug health products in pets. Just because a product is natural does not mean it is safe. 

All medicines and medicinal plants are potentially toxic if used inappropriately or given at high doses. Supplements can also have side effects, like pharmaceuticals. Few supplements and herbs have been subjected to rigorous scientific trials to determine their efficacy.

Although the information in this handout may be helpful, it also may be incomplete and may not represent the full range of effects the supplement could have on your pet.

How is bilberry given?

• Bilberry comes in gel, liquid, tablet, and powder forms.
• All forms are given orally (by mouth).
• May be given with food or on an empty stomach.
• Follow your veterinarian’s instructions on administering this medication.

This supplement should take effect within 24 hours, although outward effects may not be immediately noticeable.

What if I miss giving my pet the supplement?

If you miss a dose, give it as soon as you remember. However, if it is almost time for the next scheduled dose, skip the missed dose and resume the regular dosing schedule. Do not give the pet two doses at once.

Are there any potential side effects?

Bilberry may cause the following side effects:

• Mild vomiting and/or diarrhea

Serious adverse reactions may occur. If any of the following signs develop, stop giving bilberry and contact your veterinarian immediately:

• An allergic reaction such as irregular breathing, rash, fever, puffiness and swelling around the face

Drug sensitivities can develop over time with repeated exposure. Your pet may have no reaction after the first few doses, but may develop a sensitivity later. It is important to watch for signs of an allergic reaction over the entire course of treatment.

Other side effects may occur. If you notice anything unusual, contact your veterinarian immediately. This short-acting medication should stop working within 1–2 days, although effects may last longer in pets with kidney and/or liver disease.

Are there any risk factors for this supplement?

DO NOT USE bilberry in:

• Pets who are allergic to any component of the medication

USE WITH CAUTION in:

• Pets that are pregnant or nursing

Are there any drug interactions I should be aware of?

The following medications should be used with caution when given with bilberry:a

• Insulin
• Warfarin

Certain medications may interact with bilberry, so it is important to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking before starting any new treatment.

Is any monitoring needed with this supplement?

• Your veterinarian will let you know when and how they want to reassess your pet to ensure the supplement is working and not causing side effects.
• At home, monitor for any abnormal changes. If any occur, discontinue the medication and contact your veterinarian.

How do I store bilberry?

• Store the medication according to manufacturer’s directions
• Keep the container out of reach of children and pets.

What should I do in case of emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility. Be prepared to provide information about the product and your pet’s weight and symptoms.