The astute observations of researchers at Michigan State University have led to a nationwide dog food recall.

Connecticut-based dog food manufacturer Blue Buffalo Co., Ltd., has recalled certain packages of its dog foods sold under the brand "BLUE," the U.S. Food and Drug Administration (FDA) announced. The recall was due to possible higher than normal levels of vitamin D in the food.

The recall is the result of the observations of scientists at the Michigan State University’s Diagnostic Center for Population and Animal Health (DCPAH). When the Center began receiving samples from all over the country from hypercalcemic dogs, DCPAH endocrinologist Kent Refsal, DVM, PhD, noticed a pattern and the team investigated further. Refsal reported his findings in a paper on the MSU website.

"Among the possible differential diagnoses of hypercalcemia in dogs, hypervitaminosis D is generally viewed as an uncommon occurrence," Refsal wrote. "Since July 2010 to the present, there has been a series of 16 test results in dogs that were indicative of hypercalcemia related to excessive intake of vitamin D, which we would regard as a high prevalence over this period of time. These test results included an elevation of ionized calcium, low-normal or low concentrations of parathyroid hormone, and/or an elevation of 25-hydroxyvitamin D."

Refsal said the dogs (13 purebreds and three mixed breeds) ranged in age from eight months to eight years old. Most of the dogs were reported to have increased thirst and urination, with some suffering weight loss, loss of appetite or elevated levels of nitrogenous compounds in the blood (azotemia).

"In telephone conversations with veterinarians, there was discussion as to possible sources of excess vitamin D," Refsal wrote. "It soon became apparent there was a common factor in these 16 dogs. All were being fed a commercial Blue Buffalo wilderness chicken diet. Over this time period, there have been other associations with hypercalcemia and this brand of food, but with no additional testing."

Scheduling error

According to the FDA recall announcement, a manufacturing scheduling error caused the elevated levels of vitamin D in the food.

"Immediately before producing the ingredients for these specific production runs, the supplier had run a product for another customer that contained a more potent form of Vitamin D used in chicken feeds," the announcement says. "It is now believed that there was some level of carryover of this Vitamin D product into the ingredients for the specific manufacturing runs of the BLUE products, thereby increasing the Vitamin D activity to unacceptable levels in the Blue ingredients."

In an open letter on its website, Blue Buffalo says it will reimburse"any veterinary or testing expenses related to illness caused by these products."

The FDA Center for Veterinary Medicine (CVM)announced the recall on its website after Blue Buffalo voluntarily recalled specific dry dog foods. The products below are the affected foods.

Product

Bag Size

Best Used By Dates

BLUE Wilderness Chicken (Dog)

4.5 lb., 11 lb., 24lb.

JUL1211B, JUL1311B, JUL2611Z, JUL2711Z, JUL2811Z

BLUE Basics Salmon (Dog)

11 lb., 24 lb.

AUG2111B, AUG2211B

BLUE Large Breed Adult Chicken

30 lb.

SEP 22 11 P, SEP 23 11 P, OCT 26 11 P

What to do

The FDA says that to date there have been 36 cases nationwide of dogs reported with symptoms consistent with elevated Vitamin D in their systems as a result of being fed these products. In all cases the symptoms have subsided upon discontinued use of the products, with no apparent long term health consequences.

No deaths have been reported associated with the recalled food, but veterinarians should watch for signs of hypercalcemia in their patients if they are being fed affected Blue Buffalo foods.

The American College of Veterinary Internal Medicine (ACVIM) released the following information for veterinarians on hypervitmainosis D (aka vitamin D toxicosis):

• Vitamin D toxicosis (either acute ingestion of a large dose or chronic ingestion of a marginally increased dose) results in hypercalcemia through a combination of factors, including increased absorption of calcium from the gastrointestinal tract, stimulation of bone resorbtion, and enhancing calcium absorption in distal renal tubules. Serum phosphorus is also often increased in these patients as well. These derangements result in dystrophic mineralization of soft tissues with various consequences depending on the system affected. This includes muscle tremors, renal failure (polyuria/polydipsia), anorexia, vomiting, diarrhea/constipation, gastric ulceration, arrhythmias (bradycardia/ventricular premature contractions), seizures, and dyspnea.
  
• Besides laboratory derangements associated with the body system affected, canine patients with vitamin D toxicity have an elevation in ionized calcium levels, low-normal or decreased concentrations of parathyroid hormone (PTH), and an increase in 25-hydroxyvitamin D levels.
  
• It is important to realize that other diseases should be investigated in canine patients with hypercalcemia, including neoplasia (lymphosarcoma, anal gland carcinoma, and multiple myeloma), hypoadrenocorticism, chronic renal failure, primary hyperparathyroidism, granulomatous disease, and rodenticide toxicity.
  
• Treatment varies based on the patients status, but options include supportive care (promote calciuresis with IV fluid therapy), peritoneal dialysis (for severe azotemia/hypercalcemia), antiemetics/gastroprotectants/antibiotics (for gastric ulceration and to prevent bacterial translocation) and of course, discontinuation of the diet. Additional medications that can be considered for these patients include pamidronate, glucocorticoids, and furosemide (calciuresis). Note that the release of vitamin D from soft tissue stores will take weeks to months.