Veterinarian FAQ with Petaluma’s formulator, Dr. Blake Hawley


Dr. Blake Hawley is a veterinarian with over 25 years of experience developing scientific diets and pharmaceutical delivery products for pets. He earned a doctorate in veterinary medicine from NC State University, completed his post-doc training at Utrecht University and also holds an MBA from the University of Kansas.

Dr. Hawley is Petaluma’s lead formulator and works closely with other veterinary nutrition experts to design our plant-based food formulas. Dr. Hawley understands that many clinical veterinarians have had limited exposure to nutritional developments in pet food and may have concerns when a client asks them about a new brand or product. In this blog post, we will set out to answer some of the most common questions we tend to receive from veterinarians about plant-based formulas and Petaluma specifically.

What specific ingredients do you use in your plant-based dog food, and what is the primary protein source?

Relative to traditional pet food, Petaluma is very transparent with its diverse ingredient label. In addition to the full ingredient label, Petaluma shares a full nutritional analysis on its website. For example, the adult formula ingredients are available here and the nutrient analysis is available here.

We formulated Petaluma with a mix of protein sources, specifically organic chickpeas, human-grade organic peanut butter, organic flaxseeds, potato protein, dried brewer’s yeast, and pea protein. Organic chickpeas are listed as our first ingredient in our adult and senior formulas but represent less than 15% of the total. Pulses (chickpea and pea protein) represent less than 20% of our diet, so the Petaluma formulas are not considered a high-legume diet.

Lastly, all ingredients used in Petaluma’s formulas are AAFCO-approved and have a solid track record of use in dog food and treats - we’re not using any novel or proprietary ingredients to achieve a full nutritional profile. There are plenty of great options to harness within the plant kingdom for a complete diet.

How do you ensure that your plant-based dog food provides all the essential nutrients required for canine health?

All essential nutrients can be sourced without animal-derived ingredients, so the formulation process is similar to other meat-inclusive canine diets. Using plant-based protein and fat sources just changes which nutrients require additional consideration, as minerals like phosphorus are abundant in chicken recipes and more scarce in plant proteins.

First, we align on the nutritional goals for the food. We designed our initial adult and senior formulas to be higher in protein, dietary fiber, and omega-3 fat than the typical dog food, with a target of 25-30% of calories from protein. We also establish guidelines around our ingredient approach, including certain target compositions of food groups (i.e which legumes, whole grains, vegetables, and oilseeds to include)

We then use the same software virtually every large pet food company uses to calculate the different combinations of ingredients we could use to hit our nutritional target and fulfill all essential nutrient requirements. There are many feasible combinations of inclusion rates that would be nutritionally acceptable, and we use factors like ingredient sustainability (i.e. barley vs. rice water requirements) and palatability to choose the permutation that we have proven dogs will like and will meet our sustainability targets. Once the formula is dialed in and reviewed by our team of experts, we run a test batch at the bakery and send it to a laboratory for actual nutritional analysis (versus the “book” values the formulation software provides) to ensure dogs are getting exactly what we promise on our labels. Depending on the analysis, we either move forward with production or make slight adjustments. For each batch of food, we send a sample to a laboratory for analysis to ensure it meets our standards and nutritional requirements, as we recognize slight variations in plant quality can affect the nutrient content.  This activity is more than the large companies do.

Most commercial pet food companies get away with just sharing a macronutrient profile, but the Petaluma team understands that plant-based formulas need to show a deeper level of detail to help consumers (and their veterinarians) feel confident that their dog has everything they need in the absence of animal protein. 

Have you conducted feeding trials or nutritional analyses to confirm the adequacy of your product for dogs?

In addition to my contributions as a veterinarian and experienced commercial formulator, Petaluma had its formulas reviewed by American College of Veterinary Nutritionists (ACVN) diplomats to verify completeness and provide feedback. As mentioned previously, Petaluma conducts a full AAFCO nutrient analysis at multiple stages of formula development and production and commissions digestibility testing at a university laboratory to assess bioavailability, including individual macronutrients.

We did not structure a formal feeding trial using AAFCO procedures and instead took the 'formulated to meet' path and invested in additional tests to evaluate nutritional quality. Petaluma did conduct an at-home feeding trial with 30 companion dogs including 12 that fully transitioned to Petaluma 6 months before we publicly launched. Our at-home trial included owner surveys and regularly scheduled veterinary exams. However, that at-home trial did not meet the AAFCO trial standards - and was not expected to - as it relied on owners to collect and submit data and was understandably incomplete. 

Are there any additives or supplements included in your plant-based dog food to address potential nutrient deficiencies?

Yes, we have added supplemental amino acids as well as some vitamins and minerals, which is a standard (and recommended) practice for complete dog food whether it includes meat or not.

The core ingredients in our formulas provide the vast majority of essential micronutrients that exceed (without supplementation) the minimum dietary requirements. Some micronutrients must be supplemented as they are not naturally present in plant-based food (i.e. vitamin B12 and taurine) and others are more challenging to achieve a perfect balance (and safety margin) using only whole food ingredients. We add small amounts of supplemental isolated micronutrients to ensure the dog has plenty of vitamins and minerals to work with, even if the bioavailability may be slightly lower on some synthetics/isolates.

We add supplemental amino acids dl-methionine, taurine, and l-carnitine. Synthetic amino acids are often more bio-available than the organic versions included in more complex proteins, as the complex structure of proteins (as well as the presence of other compounds in the ingredient like dietary fiber) can inhibit absorption. For example, methionine in lamb meat appears to be more susceptible to being denatured during cooking, resulting in lower bioavailability. Taurine supplementation in particular has been studied extensively and dogs fed supplemental synthetic taurine show significant increases in blood taurine levels (i.e. taurine that has been metabolized and made available for use in the body). Supplementing taurine has become a standard recommendation for commercial dog food diets (regardless of protein source) in part as a reaction to concerns around diet-related DCM. 

In terms of vitamins, we have supplemented our formulas with a vegan vitamin D3, which has been shown to increase the amount of vitamin D-derived metabolites in the blood more than supplementation with vitamin D2. Thiamine is naturally included in our food through ingredients like brewer's yeast, and we have additional supplementation in our formula via a synthetic source of thiamine mononitrate (vitamin B1).

All high-quality commercial dog foods use some mineral supplements (like iron, zinc, and copper) to ensure it is bioavailable to the dog.  We use organic, chelated forms of these minerals (i.e. minerals bound to amino acids) that have very high bioavailability even though they are more expensive. For example, chelated iron combines the absorption advantages of animal-derived heme iron, but the lower oxidation of plant-based, non-heme iron. We also use a very small amount of supplemental selenium via a complex of selenium and salt (sodium selenite). Our food naturally contains organic selenium via brewer’s yeast, so the addition of a small quantity of sodium selenite is an additional insurance policy for bioavailability but well below the safe upper limit. 

Can you provide information on the digestibility and bioavailability of the nutrients - and particularly protein - in your plant-based dog food?

As in human nutrition, digestibility is a bit of a double-edged sword, as both very high digestibility and very low digestibility can come with nutritional concerns. Very low protein digestibility is a clear nutritional problem, as a deficiency in absorption of any limiting amino acid can quickly result in metabolic deficits. However, extremely high digestibility is also typically coupled with low dietary fiber content and/or highly processed ingredients that have been stripped of more complex micronutrients. For example, a Big Mac is extremely digestible but low in nutrient density. Plant proteins have been used in canine diets for nearly a century, but some folks have expressed concerns that plant protein sources are less digestible and therefore lower quality than animal-based proteins. Our goal with Petaluma’s formulas is to provide dogs with complete, high-quality plant-based proteins that are easily digestible without sacrificing dietary fiber from whole foods that (definitionally) reduce overall digestibility.

To validate our approach, we conducted digestibility studies at a university laboratory that pioneered an in vitro approach and validated it against in vivo digestibility models to accurately model the digestive system of a dog (without harming dogs or other animals for product development). The studies validate that dogs absorb the nutrients - and particularly protein - in our food at high rates. We share our digestibility study results on our website or via this link. Our latest study showed that our protein sources are 93% digestible, which was impressive compared with the lab’s average for animal protein digestibility in dry dog food of ~89%, and meat meal ingredients often score below 85%.  

Are there any specific recommendations or guidelines for feeding your plant-based dog food to dogs with certain health conditions or dietary restrictions?

Complete and balanced plant-based dog food is a healthy choice for most adult and senior dogs. Petaluma does not make a growth-stage formula (puppies) and our diets are not suitable for dogs until they have reached their adult weight. Like with any new food, we recommend a slow transition over days or weeks to introduce your dog gradually and monitor for signs of indigestion or possible allergy. Most dogs can transition to Petaluma easily, but dogs that had very low fiber diets previously (ex. meat-heavy raw and fresh foods) may need a longer transition period for their microbiome to adapt to the increased fiber content. We have a video here explaining how to transition to Petaluma successfully. 

Plant-based diets can be an excellent choice for dogs with food allergies, as animal proteins are the most common food allergens. I have previously worked on therapeutic commercial dog food formulas and understand that veterinarians will often prescribe hydrolyzed diets (HA / hypoallergenic) as an elimination diet. I would recommend using a plant-based formula like Petaluma instead of a hydrolyzed meat-based diet as a long-term solution to manage allergies. High-quality meat-free diets are formulated for long-term use and source nutrient-dense plant proteins (free from common allergens) and provide a balanced and nutritionally complete diet (and are likely much more palatable). For additional information, we have a blog post on our site about hydrolyzed diets that can be useful to share with interested clients. 

Many veterinarians also recommend plant-based proteins for dogs with CKD and most vet-prescribed therapeutic kidney diets include primarily plant-based proteins. Plant-based proteins are naturally lower in phosphorus and sodium and are less acidifying (more alkaline) than animal protein, and limiting these nutrients decreases the amount of work kidneys need to do to filter blood. Similar to veterinary-prescribed diets, Petaluma’s plant-based formulas are relatively low in total phosphorus (~0.8% DW) and sodium (~0.2% DW). However, both diets are relatively high in protein, as higher protein levels are typically recommended to maintain strength in senior dogs that face a slowing metabolism and lean muscle loss. However, once a dog has been diagnosed with CKD, this elevated protein level may be inappropriate and place an unnecessary burden on already impaired kidney function. Additional information on CKD diets can be found on our blog here.
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