Beginning in the 1990s, veterinarians began seeing dogs who developed acute kidney failure after eating grapes, raisins, or currants. Despite extensive research, the component that caused the problem was never identified; it couldn’t even be narrowed down to any particular part of the fruit, such as skin, stem, leaf, seed, or flesh.
While chronic kidney disease (CKD) is commonly seen in older cats and dogs, it is usually due to a chronic, low-grade, inflammatory process called glomerulonephritis. Recent research suggests that, in cats, contributing factors may include consumption of fish, and the vaccine for panleukopenia (feline distemper). (Click here for more info on CKD in cats.)
In contrast, dogs who developed grape/raisin toxicity were found to have damage and even necrosis (tissue death) in the proximal renal tubular epithelium, which is a different location in the kidney.
Grape/raisin toxicity causes signs of illness within hours, and kidney failure develops within days; as opposed to the gradual development of chronic kidney disease over many months or years.
Signs of acute grape/raisin/currant toxicity include vomiting, diarrhea, lethargy, loss of appetite, increased drinking and urination, and dehydration.
Grape/raisin/currant toxicity has been documented only in dogs, although there have been anecdotal reports of a similar problem in cats and ferrets.
A reader recently asked about the issue of grape/raisin toxicity in dogs, and what it means for the Chardonnay grape seed oil in the Omega-3 supplement MOXXOR.
After thoroughly researching this issue, we have concluded that:
- Even though nobody knows exactly what the toxic element is, poisoning cases have involved seedless grapes as well as seeded varieties, so the toxic factor is not in the seeds.
- The toxic reaction appears to occur in only individuals with a particular susceptibility. However, whether that susceptibility is genetic or otherwise is unknown.
- The grape seed oil in MOXXOR is from Chardonnay grapes; there have been no reports of toxicity in dogs related to that type of grape.
- The toxic dose of raisins in dogs is typically about 1/2 ounce of raisins per 10 lb. of body weight; or 3 ounces of fresh grapes per 10 pounds.
- There are 28 grams in one ounce; and there are five MOXXOR capsules in 1 gram. The grape seed oil comprises only a small fraction of the 350 mg total oil in the capsule. The actual amount of grape seed oil is vanishingly small compared to the suspected toxic dose range, so it is impossible for a reaction to occur even with higher doses of MOXXOR.
We are, therefore, 100% comfortable with recommending MOXXOR for any species.