Why Aren’t Raw Pet Food Companies Testing for Avian Influenza?

If you’re looking for a quick, short summary of the bird flu situation please check out our Avian Influenza FAQs. If you’re looking for something more in depth, you’re in the right place!

Ever since we saw the first few cases of bird flu in cats late last year, the most common question we’ve gotten is  if and when we would be testing our food for the virus . Every pet food brand wants to test, but the response you’ve probably already seen is that there isn’t a commercially available, validated test for avian influenza in raw meat products.

“But the FDA is testing and finding the virus in pet food so why can’t you?” This topic is more complex than it seems so let’s look at how testing works and the challenges to it being more widely available. This post represents our best current understanding of this subject through conversations with researchers & scientists. 

There are usually two phases to testing for viruses and bacteria in food. The first part is a preliminary test that looks for the presence of DNA/RNA from pathogens. If no genetic material is found, then you have a negative result — otherwise you have a presumptive positive or non-negative result. However, just because you find genetic material, it doesn’t mean that the cells it came from is actually infectious since they could be dead cells. This is where part 2, a confirmatory test, comes in. You confirm that the genetic material is viable by seeing if you can actually grow the pathogens. Here’s how this works for avian flu: 

• Genetic material is isolated from a sample and goes through several cycles of replication to amplify the viral RNA so that it can be detected by instruments. Reverse transcriptase PCR is used in this case since the virus is RNA and not DNA based.

• The result is either 1) negative if none or insufficient genetic material was detected OR 2) presumptive positive/non-negative which needs to be confirmed. 

Note: There is another type of testing (ELISA/AGID) for Avian Influenza based on detecting whether or not the sample contains antibodies to the virus produced by the immune system during an infection. This type of testing is usually conducted on samples from live animals AND is also known to be less accurate than PCR tests so they are not being considered for meat products.

Each type of testing faces its own challenges with confirmatory testing presenting the greatest complexity. 

An important part of creating any test is the validationprocess to make sure the test is accurate. This boils down to having samples with the virus at different concentrations and samples without the virus, running the RT-PCR test, and making sure it accurately returns the positive and negative results. The following are some but not all of the work a commercial lab will need to complete:

1. Determine which strains the test will detect : The current dominant H5N1 strain is just one of many highly pathogenic avian influenza strains. Laboratories will need to test at the appropriate level of specificity so that results are not too broad to be actionable but not so specific that it becomes outdated as new strains emerge.
   
   

2. Determine how to effectively extract viral RNA from pet food samples: Although testing is currently performed on milk and samples from livestock, pet food is a very different product matrix so new methods are needed to extract the viral genetic material. For example, Salmonella screening has different preparation methods (Section C) depending on the type of food being tested.
   
   

3. Procure the virus to conduct the validation test : Highly pathogenic avian influenza is categorized as a high risk pathogen that requires Biosafety Level 3 (BSL-3) standards for handling. Only a small percentage of laboratories meet these standards. Alternatively, a low pathogenic substitute can be used but labs will need to find or create a strain that would yield the same results as the highly pathogenic strains in the RT-PCR test

Images: BSL-3 laboratories have stringent protocols to ensure safety & containment

Commercial laboratories should be able to successfully develop a RT-PCR test but it will take time and resources. This would ideally involve collaboration across multiple laboratories to check that methods and results are repeatable and consistent. 

1. Limited Testing Capacity: 

   • To our knowledge, this test is currently only conducted at the National Veterinary Science Laboratory (NVSL) in Iowa since it is complex, time-consuming, and requires a BSL-3 laboratory. Testing capacity at NVSL is limited so it is prioritized for regulatory purposes (follow ups to consumer complaints) and the human food supply (ex. milk, live poultry flocks) and that’s why it's not available for the public or companies.

   • The test itself is complex and takes ~2 weeks to complete since eggs must be grown to ~7-12 days old before inoculation and are held for an additional 7 days after inoculation.
     
     

2. Challenges with Virus Extraction and False Positives :

   • A chicken embryo is fragile. It can easily die to other compounds like bacteria, other viruses, acids, salts etc if they were accidentally introduced.

   • A pet food recipe is considered a complex matrix full of these various compounds, making it difficult to extract a clean viral sample for inoculation.

   • Essentially, the pet food product matrix interfereswith the virus extraction so if the egg doesn’t survive, there’s uncertainty if it was due to the virus OR other compounds in the inoculum (a false positive).

   • So even if there is more capacity to conduct these egg tests, the testing & extraction methods need to be refined so that results are more accurate.
     
     

3. Limited Regulatory Bandwidth 

   • Staffing cuts at regulatory agencies such as the FDA and USDA have significantly affected their ability to improve testing methods, increase capacity, and share guidance with industry.
     
     

Between the two, confirmatory testing will be far more challenging to commercialize due to how complex the egg test procedures are and the more significant scientific challenge of cleanly extracting the virus sample. There may be other methods to determine virus viability but that will require additional time and research. 

A RT-PCR test will likely become commercially available before a confirmatory test. If so, should companies start using the RT-PCR test first? This is a difficult question. Anytime you’re testing, you need to know what the plan is if you receive a positive result since there are significant implications whether that’s rejecting your raw materials, disposing of unsold products, or initiating a recall. That’s why confirmatory testing is so important for ensuring these big decisions are made with the most accurate data possible. This is especially important if a step within the production process is inactivating the virus so the finished product may contain viral genetic material that WILL result in a presumptive positive through RT-PCR, but there won’t be a way to confirm if it is viable or not.

Ultimately, it will be up to each company to decide on their testing strategy as commercial tests become more available. A possible approach would be to test raw materials via RT-PCR so that better sourcing decisions can be made and avoid the larger challenge of testing finished products while confirmation tests are not yet widely available. 

Aside from knowing whether or not a pet food is safe and doesn’t contain the virus, scientists also need access to testing in order to conduct validation studies to determine whether a technology effectively inactivates the virus. Within a validation study, researchers will need to determine the following:

1. How much virus should I inoculate into my sample for testing?
   This requires RT-PCR testing to develop a baseline understanding of how much viral load could potentially be present in raw materials
   
   

2. Was my treatment effective?
   Since samples are inoculated with a high viral load in a validation study, RT-PCR has a higher likelihood of showing presumptive positive results. A confirmatory test is needed to determine if the genetic material detected is viable and if treatment was effective.
   
   

The process of designing a validation study to determine what interventions are effective against avian influenza is worthy of its own post. If you’re curious about the details there, leave a comment and if there’s enough interest, we’ll put something together! 

While all these challenges seem daunting, we’re confident in the safety of our recipes. We’ve remained in close communication with our suppliers, are deeply familiar with and trust in their testing & biosecurity practices to keep their flocks and our food supply safe. We’ve updated our food safety plan to address the risks that H5N1 poses and have been closely monitoring HPAI cases nationwide which have steadily decreased since the start of the year. Finally, we’re actively working with scientists and researchers to address the very challenges detailed above. As we learn more, we’re committed to sharing that knowledge with you guys as we’ve done here, and don’t hesitate to let us know what other topics you’re interested in!