On October 3, 2009, Diamond Pet Foods announced that they had voluntarily withdrawn from distribution two brands of cat food Premium Edge Finicky Adult Cat and Premium Edge Hairball cat. The recalled bags are those with the following date codes.

• RAF0501A22X 18lb
     
• RAF0501A2X 6 lb.,
    
• RAH0501A22X 18 lb.
     
• RAH0501A2X 6lb.
     

SO far, based on calls from pet owners and veterinarians, the problem appears to be centered in the Rochester, NY, area. The company has contacted all retailers and outlets to which these lots were shipped and asked them to pull the product from the store shelves. The retailers were also asked to contact their customers via email or telephone requesting them to check the date code of the food. However, pet owners who feed either of these cat food brands should check the date codes regardless of whether they are contacted.

Due to the recalls in 2007 relating to contamination of pet foods with melamine, one might immediately assume contamination. However product testing of affected bags revealed that the cat foods were deficient in the water-soluble vitamin Thiamine, also known as vitamin B1, and that there were no contaminants.

Thiamine is an essential vitamin, meaning cats and dogs cannot synthesize it themselves. It’s required for the conversion of dietary carbohydrates to energy. Because the central nervous system relies solely on carbohydrates for energy, the central nervous system is severely affected. Cats on these diets may display nonspecific signs of lethargy and loss of appetite, followed by more specific neurologic symptoms ranging from mild balance issues to life-threatening seizures. The signs can present suddenly.

The first veterinarian to see and report a case was Dr. Susan Hubbard of Stone Ridge Veterinary Hospital in Rochester, New York. “I saw two young, previously healthy indoor cats from the same household on the same day with the same signs-walking as if drunk (termed ataxia) and in one cat this progressed to seizures. Neither cat had a fever or any indication of infections that could cause such signs so suddenly.”

Hubbard’s coworker, Dr. Linda Banks, presented the case to an online community of veterinarians at VIN (Veterinary Information Network). The VIN network of private practice veterinarians and specialists offered suggestions regarding important questions to ask. But ultimately the toxicologists, internal medicine specialists, and private practitioners alike were stumped, suggesting that, this was indeed an atypical case. A VIN member from the ASPCA poison control center also confirmed that they had not received reports of strange toxic ingestions with this history and signs.

The problem was that the presentation screamed toxins-but the owners swore that there was nothing in the house or basement that could have been toxic. No accidental ingestion of a visitor’s antidepressants or illicit drugs, no new food, no flea products, no exterminator house treatments.

Then Hubbard remembered that several days before she’d seen an indoor-only cat owned by an employee. The cat presented due to sudden seizure activity and also had no history of toxins or drugs. Tests for feline leukemia, feline AIDS, heartworm disease, toxoplasmosis and feline infectious peritonitis as well as other lab tests were normal.

The red flag was that the three cats all ate Premium Edge cat food, which alerted her that this might be a cause and that she should contact the manufacturer, Diamond Pet Foods. When she called, she found that Diamond Pet Foods customer service representatives had already been receiving complaints from retailers about customers returning bags of food. According to Hubbard, customers had complained of an “unusual or off odor” and reluctance of cats to eat it suddenly.

Says Dr. Janet Rettenmaier, Director of Veterinary Services at Diamond Pet Foods, “We monitor complaints on a daily basis and can track our products across the continent as well as internationally. I review cases on an individual basis. If something atypical, such as an increase in calls per lot number or formula, or unusual complaints or clinical signs, it is monitored closely.”

Hubbard worked closely with Diamond Pet Foods to determine the cause and treat the cats, and finally the problem was discovered to be thiamine deficiency in several food lots. Says Hubbard, “Diamond Pet Food has been working closely with veterinarians and has been extremely forthcoming and helpful. They were right on the ball getting the testing done, communicating with us what they were finding, and helping clients to cover the bills.”

Even prior to finding the thiamine deficiency, Hubbard notified the veterinary community of the food-related issue through email announcement to hospital directors and the local veterinary medical association. So the word spread quickly.

In total, Hubbard says there have been 14 confirmed cases. These are cats who were on the affected foods and showed decreased appetite, vomiting, a drunken walk, mentally dull, dilated pupils, decreased to absent response of the eyes to light, blindness, seizures, severe flexing of the head, rigid posture, increased respiratory rate and low body temperature.

Luckily for these cats, anti-seizure medications, thiamine supplementation, and supportive care brought about a rapid turnaround within 24 to 72 hours. And even for those where the exact cause wasn’t known, the cats were eating on their own quickly with just supportive care. They were placed on commercial foods that had the appropriate levels of thiamine and so recovered quickly.

Oddly, thiamine deficiency is not that common in food because, even though thiamine degrades during the processing, commercial food companies take this into account when supplementing the foods with vitamins. Generally thiamine deficiency occurs when cats are put on a diet high in raw fish containing an enzyme called thiaminase that degrades thiamine. Deficiency on such diets high in this thiamine-degrading enzyme usually take 23 to 40 days to develop. A study of cats on low thiamine diets, on the other hand, showed that cats can develop non-specific signs such as lethargy and vomiting in 1 to 2 weeks and neurologic signs in 2 to 5 weeks. In the case of the Diamond cat foods, the food had been purchased in late July and early August. So neurologic signs took 4 to 6 weeks to appear.

So how can you prevent such problems? According to board-certified veterinary nutritionist Jennifer Larson, an assistant professor of clinical nutrition at the Veterinary Teaching Hospital at the University of California, Davis “I don’t think you can predict this. We’ve seen this problem in canned diets, kibble and home cooked diets. However, most of the cases I’ve seen personally have been associated with smaller manufacturers, although Diamond is a large company with a long history of experience with various brands. Hopefully, we will discover the exact cause of the error and that this is an isolated incident that will lead to improved quality control.”