As you've heard in the news, they apparently don't know what toxin is causing the ARF. One lab found aminopterin, another found melanine... FDA says melanine isn't known to cause ARF in dogs but they don't have many mammalian studies, and they don't have any studies done on cats so they aren't sure, but they do know that cats react adversely to a variety of substances at significantly lower concentrations than other mammalian species do, etc. In other words, the-powers-that-be don't apparently know what toxin, exactly, is causing the ARF.
One of the reasons Vets haven't published the cause is because they probably didn't recognize there even was a spike in ARF cases until after the recall when they were asked to look at their records. Each individual vet may have seen only 1-2 cases more than normal, so it didn't seem like a spike to that individual vet, so they didn't do any more extensive laboratory testing (of blood, urine, or necropsy, etc.) on the individual animals in their practice that died. They probably presumed it was another case of antifreeze poisoning and closed the case when the animal died.
Then the recall happened... and someone asked Banfield Pet Hospitals about their records. Banfield reviewed their records for 600 hospitals and compared the number of cases of ARF to similar time periods and notices a spike in cases. But as I said, this all happened after the fact, so they didn't notice it as it was happening. (They don't have a person dedicated to reviewing all veterinary cases to look for spikes in certain symptoms.)
Banfield has 600 hospitals and they are linked by a database/computer. Most Vets are not linked to a central database. The Veterinary Information Network has about 30,000 members. They are currently conducting a survey of their members on this topic. As of a few days ago, about 10-20% of their members had responded to the survey, and they had (I'm going from memory here) about 471 total cases and about 104 deaths reported. If that's 10-20% of their Vets reporting, that extrapolates to about 520-1040 deaths. Statistically, that's not a significant number relative to the millions of dogs/cats in the country. But each death is significant to the pet owner.
Your premise about 60 million dogs/cats isn't quite accurate though, because (a) you are counting all pets, whereas Menu Foods has said they feed about 5 million pets a day, and (b) if 2,000 more animals die than normal, that's only 0.04% higher than normal for that 5 million pets, or 0.0017% of the 120 million pet population, so it would be very hard to notice this spike on a statistical basis unless you were specifically looking for it (which Banfield did after they were asked to review their records). In other words, the spike wouldn't be statistically "substantial" at all, but the actual number of deaths (if it's 2000) is obviously substantial to 2000 pet owners. And in Oregon, approximately 2 out of 3 pets sickened by the food have survived (so far), so double the number of deaths to get the number of sick.
I guess I'm confused what your skepticism is about. Are you not believing there is a recall? Are you not believing there is a contaminant in the food? Are you not believing that pets are dying from eating the food? Are you not believing individual humans reporting, because it's not the FDA or some other "official" source who is making the report? What exactly are you in disbelief about? Just because they haven't identified the toxin doesn't mean pets aren't dying. So what is the skepticism about/regarding? Are you believing Menu Foods when they say 16 animals have died and they refuse to update the number?
Please visit the Oregon Veterinary Medical Association's website for some "official" information if you are looking for official confirmation of dead pets, with last count 32 dead in Oregon alone, and those are numbers reported by Veterinarians to the State Vet (i.e., not alarmist individual pet owners):
Of course, I know there is a recall but I am not convinced it is warranted or appropriately directed. Furthermore, the claim of a "spike" in cases is also tenuous. The FDA's CVM has also not taken a definitive stance. I happen to know Steve Sudlof, and a board certified toxicologist, he too is skeptical. This is not like the alfatoxin in dogfood a year ago where the liver disease compatible with aflatoxin poisoning was identified in dozens of cases and the aflatoxin was also identified in dozens of dogfood samples from the same households.