Evidence supporting the use of: Cranberry
For the health condition: Pets (supplements for)

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Synopsis

Source of validity: Scientific
Rating (out of 5): 2

Cranberry is commonly included in pet supplements, particularly for dogs and cats, with the primary claim being support for urinary tract health and prevention of urinary tract infections (UTIs). The rationale for its use comes from both human and veterinary studies, though the evidence base in pets is limited and not as robust as in humans.

The active components in cranberry, particularly proanthocyanidins, are believed to prevent certain bacteria (notably Escherichia coli) from adhering to the lining of the urinary tract. In humans, some studies have shown a modest benefit in reducing the recurrence of UTIs, although results are mixed. In veterinary medicine, a few small studies and anecdotal reports suggest that cranberry extract may reduce bacterial adherence in the bladders of dogs and cats, potentially lowering the risk of infection. However, these studies often have small sample sizes, lack rigorous controls, or are conducted in vitro rather than in living animals.

Regulatory and veterinary organizations, such as the American College of Veterinary Internal Medicine (ACVIM), generally acknowledge cranberry as a low-risk supplement, but caution that strong evidence of efficacy in pets is lacking. As such, cranberry may be recommended as an adjunct to conventional therapy rather than a primary treatment. Its use is justified by a combination of plausible biological mechanism and limited scientific studies, but the overall evidence supporting its effectiveness in pets is weak to moderate, hence a rating of 2 out of 5.

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