The manufacturer of a high-end pet food, under investigation in connection with more than 70 dogs falling sick, says it will reimburse owners' vet bills and pay the cost of a new dog to replace those euthanased.

While the connection is being investigated, an exact cause of the illness is yet to be determined.

Advance Dermocare dry dog food was voluntarily recalled after a number of dogs which had eaten the food contracted megaesophagus.

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Mars Petcare voluntarily recalled Advance Dermocare in March. ( ABC News: Andrew Burch )

The rare condition causes the oesophagus to become enlarged and lose the ability to move food down to the stomach.

If dogs survive, they must be fed upright so the food does not get stuck in their oesophagus.

"With documentation, we will reimburse any ongoing vet bills for the treatment of megaesophagus in dogs which consumed Advance Dermocare produced from July 2017," the company posted on its Facebook page.

Melbourne University vet Dr Caroline Mansfield said it was investigating the outbreak and knew of 74 cases of megaesophagus where the dogs ate Advance Dermocare.

"We do believe that there is an association between the food and megaesophagus but we do have to go through several steps to prove it convincingly," she said.

Dermocare is a variety of Advance dog food, made by Mars Petcare — part of the multi-billion-dollar global Mars food and confectionery business.

The company said the known megaesophagus cases suggest diet may be a significant risk factor in the development of the condition, but its tests had not identified a root cause.

"Despite no root cause being identified, we have commenced the process of contacting pet owners to provide support, including offering to reimburse vet bills," Mars Petcare said.

Police alerted Mars Petcare to sick dogs

Melbourne University became involved after Victoria Police asked for help.

Nine of its dogs contracted megaesophagus and were being fed Advance Dermocare. One was euthanased.

"They were regurgitating and they had also had some episodes of pneumonia," Dr Mansfield said.

"One of them was so severely affected that the quality of life was not considered appropriate or ethical to continue."

Nine Victoria Police dogs contracted megaesophagus. ( Supplied: Police Life magazine )

Victoria Police alerted Mars Petcare that its dogs were ill in December.

Mars Petcare said it ran hundreds of tests on Advance Dermocare and its Bathurst factory from January, including for heavy metals, pesticides and potential neurotoxins — known to trigger megaesophagus. It said it found no causal link.

The turning point came last month, when Melbourne University asked vets across the country to come forward with cases, and they did.

Advance Dermocare was voluntarily recalled soon after.

Australia's pet food industry self-regulated

Dr Mansfield said it would likely take months for the university to determine whether there is a definitive link between the food and the condition.

"Most of the testing has never been done in dog food before, so we actually have to validate the tests in that particular food," Dr Mansfield said.

She said a different dog food and a spike in megaesophagus cases was investigated in Latvia a few years ago, but in that instance, a causal link was never found.

Australia's pet food industry is self-regulated, which meant Mars Petcare was not required to inform vets or any government authorities when it first learned of a potential issue in December.

Dr Mansfield has joined affected dog owners in calling for a shakeup of the pet food industry.

"If something like this can happen with such a particular product, I think it's really important that we try to identify what that causative link is so that we can prevent potentially other conditions occurring with other diets or other food," she said.

"I do believe there needs to be tighter regulation of the pet food industry.

"I think Australia is well overdue for having pet food regulation and there is a quality control."