There is a good chance you’ve seen a dog in your clinic (or maybe even in your own home) that was brought in for having a “poor appetite.” The dog refuses to eat a particular diet or food; maybe even something they’ve willingly and readily eaten in the past, and their caregiver is understandably worried that it could be a sign that something’s wrong. There are many possible reasons for food refusal, from learned behavioral patterns and individual preference to changes in food perception with aging or chronic disease. While various strategies can be used to improve food acceptance, it’s essential to first understand what influences a dog’s willingness to eat a food or treat. To know how to help picky eaters, we first need to know what determines palatability in our canine companions.

Is it a Dog Issue or a Diet Issue?

Understanding what drives palatability in dogs in general, and in the individual dog in particular, can help the veterinary healthcare team and caregivers at home develop strategies to work around seemingly “picky eaters”. Although the exact timing of domestication is debated, dogs adapted to life with humans sometime over the last 15,000 to 40,000 years. Over that time, they’ve learned to love many of the same foods and flavors that we do too. The drivers of palatability in dogs are not too different from their human companions. They like protein (what is referred to as umami in people foods), fat, salt, and sweet. Texture and aroma also influence food acceptance, as does the environment the meal is offered.

Discussion of diet and feeding behavior should begin even before the physical exam. Questions to ask include:

·        Is there a new addition to the household (person or pet)?

·        Has the feeding location or food brand changed?

For some dogs, mealtimes are always cause for joyous tail wags no matter what is in the bowl or where it is offered, and for others, any deviation to the meals or mealtime routine can initiate a hunger strike. Gathering additional information about dietary, environmental, or behavioral changes can often help identify a potential reason for food refusal, sometimes without the need for additional diagnostics.

The Role of Learned Behaviors at Mealtime

Sometimes what we perceive as “picky eating” is actually a learned behavior. As companion dogs have increasing become viewed as members of the family, many caregivers want to provide the same food variety and environmental enrichment they would for human children. Seeing their dog eagerly dive into a bowl of food is rewarding, and any hesitation or reluctance to eat is concerning.

However, if caregivers respond to that hesitation by adding toppers, mixers, or other foods (whether meant for pets or people), or replacing the meal completely, they may be unintentionally teaching the dog to wait for these “extras” before eating. Something better/new/different will be coming along soon; all they need to do is be patient. Over time the dog learns that refusing food leads to a more appealing option; reinforcing the very behavior they are trying to avoid.

This pattern becomes especially problematic when a diet change is necessary to help manage a chronic medical condition. What may seem like a refusal to eat a therapeutic diet may simply be the dog reacting to an abrupt change in the diet type or feeding regime. Once this behavioral pattern has been established, it may be hard to reverse, but not impossible. Dogs are creatures of habit that adapted to life with humans since pre-industrial, even pre-agriculture times. With patience and consistency, both dog and caregiver can learn to accept a new, and possible more structured, mealtime routine.

Food Effects on Food Intake

Changes to a pet food’s formulation are less common than many people think, and when they do occur, they’re rarely dramatic enough to cause a food refusal on their own. If a change from “original” to a “new and improved” version is required, responsible pet food manufacturers work hard to ensure that the flavor and nutrient profiles remain relatively consistent so that dogs can smoothly transition from the old formula to the new one.

Problems can arise once a product leaves the manufacturer though. Issues in distribution, retail storage, or even within the home environment can all affect food quality and ultimately food acceptance. Just like with our own foods, improper storage and handling can lead to spoilage. Ice cream that thaws and refreezes loses its taste and texture. Cashews stored in a hot garage become rancid and can be bitter. Deli meats left open or unrefrigerated spoil and start to grow bacteria and mold. Dog foods are no different. A frozen dog diet or treat that’s thawed and refrozen may change the aroma or texture. Dry dog food stored in a hot garage will start to oxidize and degrade, causing the fatty coating to turn rancid and unpalatable. Refrigerated dog diets that are not properly sealed can spoil quickly making it unappetizing (and potentially unsafe).

Under normal circumstances, gently warming a diet can bring out pleasant aromatics and volatile compounds that improve palatability in many cases. But excessive and prolonged heat has the opposite effect: it accelerates fat oxidation and increases the release of ketones and aldehydes, which are big detractors for a species that relies so strongly on its sense of smell.

When is a Clinical Workup Needed?

An important first step when discussing “picky eaters” with caregivers is to clarify whether their dog is ignoring just the food in their bowl or are they refusing all food. If a patient turns their nose up at their main meals but is readily and happily eating other treats and foods offered, the issue may be behavioral or related to main meal (see above). Total food refusal on the other hand is a red flag that a more complete medical workup is needed, beginning with a thorough physical examination.

Watch how the patient is moving around the room? Are they painful or reluctant to move? Palpate the abdomen for discomfort and listen for changes (increases or decreases) in gut sounds. Assess heart and lung sounds, and don’t overlook oral health. Periodontal or endodontal disease rarely causes a complete food refusal, but it can lead to changes in texture preferences (softer foods are preferred) or the way they eat (more gulping, less chewing). This could look like “food refusal” to the caregiver when really, it’s an accommodation to oral pain.

Once obvious causes are ruled out, it’s time to investigate subtler ones. Baseline screening diagnostics such as serum chemistry, hematology, and urinalysis will help identify renal, hepatic, or endocrine disorders that can affect appetite. If food refusal is accompanied by other gastrointestinal signs, such as vomiting, hypersalivation, increased borborygmus, or diarrhea, and the initial screening are inconclusive, additional testing may be warranted. This can include canine-specific pancreatic lipase (cPL) to evaluate for pancreatitis, or serum cobalamin (vitamin B12) and folate (vitamin B9) to screen for a chronic enteropathy. Imaging studies, including radiographs or abdominal ultrasound, may also provide valuable information.

Ultimately, the most effective way to a help a “picky eater” is to identify and address the underlying cause through a tailored medical and dietary treatment plan to supports both the patient’s health and is in a form the dog is willing to eat. 

Fresh Takeaways:

1.   What appears to be “picky eating” may actually be a learned behavior. Encourage caregivers to maintain consistency in both the type of food offered and feeding times.

2.   Dogs generally prefer chewy, meaty foods made with fresh ingredients. Emphasize proper handling and storage of all food types to prevent spoilage, which can lead to food refusal.

3.   If the issue isn’t related to the diet itself, a veterinary evaluation is warranted to identify any underlying medical problems. Additional diagnostics testing may be necessary to determine the source of the problem and guide development if an appropriate treatment plan.

Learn more about what influences palatability and how it’s tested.