When The Blue Buffalo Co. Ltd. was sued this week by Nestlé Purina PetCare Co., accused of false advertising, it wasn’t the first time the 12-year-old pet-food company elicited criticism from competitors about its promotional claims.

Hill’s Pet Nutrition, Inc., twice has filed complaints about Blue Buffalo with the National Advertising Division (NAD), an investigative unit of the Council of Better Business Bureaus. And twice the NAD, which reviews national advertising for truthfulness and accuracy, sided largely with Hill’s.

Nestlé Purina’s suit, filed Tuesday in U.S. District Court in St. Louis, escalates a years-long battle between older, established brands and a rapidly growing upstart with aggressive advertising.

Blue Buffalo, which firmly denies the charges in the suit, describes itself as “the leader in premium quality, all-natural pet nutrition.” Founded in 2002 in Wilton, Connecticut, the privately held company had revenues of $730 million in 2012, representing a 65 percent increase in sales since 2010, according to figures from Petfood Industry magazine.

By comparison, Nestlé Purina PetCare had revenues in 2012 of $16.2 billion. The Purina brand dates to 1894.

In court documents, Nestlé Purina accuses Blue Buffalo of false advertising, commercial disparagement and unjust enrichment. “With tens of millions of dollars in advertising and a small army of in-store marketers, Blue Buffalo has built a brand targeted at ingredient-conscious pet owners. It has become increasingly clear, however, that Blue Buffalo’s brand is built instead on a platform of dishonesty and deception,” the suit alleges.

The complaint goes on to describe the results of independent laboratory tests that belie Blue Buffalo’s claims about the absence of poultry byproducts and grains in various product lines.

The suit states that Nestlé Purina has been economically harmed by Blue Buffalo’s misrepresentations and requests the court to, among other things, order Blue Buffalo “to account to Purina for all gains, profits, savings and advantages obtained by Blue Buffalo as a result of its false advertising and unfair competition and disgorge to Purina restitution in the amount of such gains, profits, savings and advantages.” The suit seeks triple the actual damages, court costs and attorneys’ fees, plus interest. No total is specified.

Dr. Joseph Wakshlag, a Cornell University College of Veterinary Medicine nutritionist, speaking as an observer, said, "I'm shocked that Purina is filing a lawsuit, but I'm not surprised that the Blue Buffalo ingredients are not exactly what they say they are.”

In 2005, while working at a veterinary clinic in Connecticut, Wakshlag remembers Blue Buffalo salespeople coming in to introduce their products. He recalls them telling this tale about the company’s origin: The owner’s dog, Blue, had died of cancer, so the owner set out to make better food to save other pets from dying of cancer.

“We asked, ‘Where is the proof of all this?’ ” Wakshlag recounted. “ ‘Where is the data that shows it increases my dog’s life span?’ They’d say, ‘Look it’s got blueberries!’ ”

Wakshlag foresaw then that the company might get into trouble for its health claims. “I was interested to see if it would develop into something where it’s sort of false advertising,” he said. “It’s kind of sad.”

Regarding Purina’s assertion that it detected in Blue Buffalo foods ingredients that Blue Buffalo says it doesn’t use, Wakshlag surmised: “I don't know the exact nuance of the lawsuit, but for those levels to have been detected, it has to be substantial. If Purina files a lawsuit, those levels had to be high enough to be intentional."

Blue Buffalo roundly denies the allegations.

“It is an easy thing to make unsubstantiated claims, put them in a lawsuit and then publish them all over the Web to disparage and defame a company,” founder and chairman Bill Bishop wrote in a letter to pet owners posted on the company’s website. “It is quite another thing to prove those allegations.”

Bishop reiterates that Blue Buffalo uses no chicken or poultry byproduct meal, ground corn or artificial preservatives in any of its products, and says: “… we look forward to disproving the voodoo science that Nestlé Purina relied on to support their outrageous allegations.”

Meanwhile, Nestlé Purina has set up a website devoted to the suit using the domain name petfoodhonesty. In a post Wednesday reacting to Blue Buffalo’s public statement on the lawsuit, Purina writes in part: “This is exactly what we expected from Blue Buffalo, a billion-dollar company that is not being honest about the ingredients in their pet food.”

That provoked another letter from Blue Buffalo on Thursday announcing its intention to file a countersuit. “Apparently, they believe that size and money gives them the right to throw their weight around with lawyers and spin doctors to stifle competition,” Bishop writes.

He also alludes to the recall last year of Purina-owned brands of chicken jerky treats in which unapproved antibiotics were detected. “Now that’s something that might be worth a little explaining,” he gibes.

Reached by telephone, Richard MacLean, Blue Buffalo general counsel, told the VIN News Service: "It's not our intention to litigate in the public-relations arena, which is apparently the way Purina is doing it. We view this as a PR stunt wrapped around a lawsuit."

Long before Nestlé Purina took on Blue Buffalo, another pet-food maker formally challenged Blue’s promotional claims. In 2008, Hill’s Pet Nutrition, a 75-year-old company based in Topeka, Kansas, filed a complaint with the National Advertising Division over assertions that Blue Buffalo products were nutritionally superior to leading pet-food brands because they contained no animal byproducts.

NAD, an industry self-regulatory organization, looked into the matter. In its findings, the organization noted generally that “Blue Buffalo pet foods are nutritious products made using innovative processing methods” and that it “acknowledged the great care with which the advertiser chooses its ingredients…”

However, the NAD determined that Blue Buffalo products do appear to contain animal byproducts, applying the term as commonly understood by consumers. It recommended that Blue Buffalo stop claiming “no animal byproducts” about its pet foods that contain fish meal, lamb meal and/or liver.

(Animal byproducts generally are thought to include organs — lung, spleen, kidney, brain, liver — blood, bone, fatty tissue, stomach and intestines. But the definition of the term was a point of contention in the case.)

The NAD also determined that Blue Buffalo “did not have a reasonable basis for the superior-nutrition message arising from the claim: ‘Because the leading pet foods did not meet our standards, we developed a two-part product that combined a nutrition kibble with our exclusive LifeSource Bits — active nutrients and antioxidants ‘cold formed to preserve their potency.’ ” It recommended that the company remove the reference to leading pet-food manufacturers failing to meet its standards.

On one aspect, NAD supported a Blue Buffalo claim. It found that Blue Buffalo’s “feed your pet like you feed your family” motto was acceptable for its organics line. “NAD found this message to be supported by the record, which shows that Blue brand pet food ingredients are indeed healthy and carefully chosen,” it stated.

Blue Buffalo said it would consider some of the recommendations even though it disagreed with findings that were critical of its advertising assertions. It appealed the case to the National Advertising Review Board (NARB). That body affirmed the NAD findings and recommendations in early 2009.

A few months later, the NAD reported: “Blue Buffalo’s outright refusal to bring its advertising into compliance with the decisions of both the NAD and NARB represents a blatant disregard for the self-regulatory system.” It sent the issue to the Federal Trade Commission (FTC).

Following an investigation, the FTC in late 2011 stated that Blue Buffalo had made “substantial website changes, which included the removal of age-related disease claims, establishment claims and human-grade ingredients claims” and had removed “no animal byproducts” claims from its website and packaging.

In light of these actions, the FTC opted not to recommend enforcement action, but reserved the right to take action in the future.

Recently, Hill’s filed another complaint with the NAD about Blue Buffalo over nutrition claims and disparagement claims, such as: “If you are feeding one of the big-name brands, chances are you’re in for a big letdown.” It also took issue with a “True Blue test” chart that directly compared Blue and Hill’s Science Diet dry dog and cat foods.

In findings issued in March, the NAD said that Blue Buffalo engaged in misleading advertising practices involving claims about rival products, and recommended that it remove those claims from ads.

As before, Blue Buffalo expressed disagreement, offered to make minor changes and stated its intention to appeal the decision to the NARB. That appeal is pending.

"Advertising claims should be supported by strong scientific evidence," said Linda Bean, director of communications for the Advertising Self-Regulatory Council, of which NAD is a part. "The interesting thing about this case is, you're talking about companies that both have state-of-the-art science, and both are deeply invested in the veterinary science behind their food products. The question for us is whether there’s a good fit between the evidence and the advertising claims.”

Speaking generally, Bean noted that in some instances, the issue is not whether a particular advertising claim is untruthful, but whether scientific evidence supports the particular claim.

For example, “If you advertise a product aimed at an aging population, but you’ve only tested the product on people who are young and healthy, your science isn’t supporting the claim you're making,” Bean said. “Even if it's a superlative study, it may not support the claim.”

She added: “When we look at all the evidence and recommend that a company modify its advertising, we are not suggesting that the company is ‘bad.’ We assume that companies who voluntarily participate in self-regulation want to see truthful and accurate advertising in the marketplace.”