Science has validated or eclipsed a litany of old wives' tales, but the jury is still out on cranberries. Most often used for treatment of urinary tract infections or as antioxidants, cranberries have mixed reviews in medical literature. They may prove helpful for dogs and cats. Regardless, they're probably safe.
Cranberries and Health
Cranberries are evergreen shrubs or vines usually found in cooler regions of the northern hemisphere. Its fruit shares the same name.
Cranberry products -- almost always derived from the berry -- are often marketed for treatment or prevention of urinary tract infections and bladder or urinary stones, or as antioxidant-rich dietary supplements. Studies show varying degrees of efficacy, although cranberries don't increase the acidity of urine, at least in humans, as was once thought.
Cranberries' effects are usually studied in humans, not animals. Even if they prove helpful for people, that's no guarantee they'll have the same effects for dogs and cats. Still, they appear relatively harmless and may be a safe supplement.
Urinary Tract Infections
If cranberry products act as indicated, they'll increase urine acidity, helping stop the attachment of bacteria to your pet's bladder. This could help prevent or mitigate urinary tract infections, but wouldn't necessarily address underlying causes like E. coli, Staphylococcus spp., Streptococcus spp. and others.
Veterinarians evaluate and treat underlying conditions and typically prescribe antibiotics. They recommend fresh, clean water and clean litter as a first line of defense against urinary tract infections.
One in five dogs or cats contract such infections during their lives, according to at least one study. Symptoms include straining during urination; bloody, smelly urine; fever and lethargy; and urinating in inappropriate places. Contact a veterinarian about treatment.
Mixed Messages and Other Uses
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Cranberry advocates say cranberries increase urine acidity, although modern studies don't validate this claim. They could still be effective though -- just not for the reasons originally touted.
Cranberries also are ubiquitous in natural pet food, and are often marketed as antioxidants, a claim proven to varying degrees in humans.
Among a sample of 42 of the U.S.'s 93 pet food manufactures, 38 use cranberries in their products, according to a 2005 UMass Dartmouth Center for Business Research study. The same paper notes that there's scant scientific evidence that cranberries provide similar health benefits in dogs and cats as in humans.
Considering Cranberry Safety
The American Society for the Prevention of Cruelty to Animals hasn't taken a stand on the safety of feeding pets cranberries. While no evidence points to cranberry toxicity, the nonprofit notes that the potential toxicity of another fruit, grapes, was wasn't known until the 21st century. Ultimately, it notes, pet owners should follow veterinarian advice about pet health and medical treatments.
Many veterinarians agree, although some -- including college professors and doctors of veterinary medicine -- say cranberries appear relatively harmless and may be helpful adjuncts to traditional medicine.
- American Society for the Prevention of Cruelty to Animals: Cranberries
- PetPlace.com: Can Cranberry Juice or Extract be Given to Cats for Urinary Problems or Urinary (Infections)
- Marketing Management Association: UMass Dartmouth Center for Business Research -- Pet Food Study
- UC Davis School of Veterinary Medicine: Corynebacterium urealyticum Urinary Tract Infection in Dogs and Cats -- 7 Cases (1996-2003)
- Cornell University Cornell Feline Health Center: Feline Urinary Tract Disease
- American Society for the Prevention of Cruelty to Animals: Toxic and Non-Toxic Plant List -- Dogs
- American Society for the Prevention of Cruelty to Animals: Toxic and Non-Toxic Plant List -- Cats
- The Ohio State University: High Dose Antimicrobial Protocols for Canine Urinary Tract Infections
- University of Michigan Medical Center: Mechanisms of Urinary Tract Infection
- The Cranberry Bog: Natural Treatment for UTI in Dogs and Cats
- Planned Parenthood: Can Cranberry Juice Cure Urinary Tract Infections