Clinical history and patient selection for diet trials

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“So the first thing that we have to start off [with] is saying that a dedicated diet trial, today, is necessary for performing a correct diagnosis for a food-allergic dog,” began Galia Sheinberg, DVM, ESP, DLACVD, co-owner and founder of Dermatología Especializada Centro Veterinario Mexico, in Mexico City, in her lecture Practical aspects and innovations in diet trial for food allergy diagnosis, presented at the 2025 WVC Conference in Las Vegas, Nevada. However, as Sheinberg explained, not all “itchy” patients should go on diet trials, and a detailed clinical history could help determine if the patient is a suitable candidate for this test. Among many points she presented in her lecture, Sheinberg shared some common errors that are made by veterinarians relating to diet trials.

According to Sheinberg, one common mistake veterinarians make when it comes to canine patients experiencing pruritus includes recommending a diet trial to each one of these patients, in every circumstance. “We have to understand when it’s really worth recommending a diet trial,” emphasized Sheinberg.¹

Oftentimes, the patient criteria for starting a diet trial are wrong, explained Sheinberg. “Maybe this dog was never itching before and it’s their first time they’re having issues, and somehow, automatically, they get prescribed or recommended a diet trial,” she continued. “So maybe [for] those dogs [it] was not necessary. …Maybe they had another diagnosis that wasn’t even related to their diet.”

“And most of the patients who are on a specific diet were never challenged, so they believe they’re on the right diet, but they’re still struggling,” said Sheinberg. To address this issue, she explained that taking a thorough clinical history is crucial. For veterinarians or clinics that may not have the time to go through a detailed clinical history with clients, developing a questionnaire or form for clients to fill out before the consultation may offer a solution.

When discussing feeding history with clients, it is important to know not only what the patient is currently eating, but what their diet has been like in the past. Information like whether the patient has been on a hydrolyzed or protein-selected diet, and if it was done correctly, should be discussed.

The fat fecal chart in the patient’s gastrointestinal (GI) history is also important. “Nowadays, as dermatologists, we understand that a lot of our patients have GI disturbances, and [clients] come in and… they don't tell us about it unless we ask. So, we need to know if [patients are] having any GI disturbances at all, how many bowel movements per day they're having, etc.,” explained Sheinberg.

If the patient has been on medication, and how they responded to it, needs to be discussed as well. As Sheinberg explained, some dogs have been on numerous medications, leading to the perception that they have failed every treatment. “But you really need to find out the timeline and the reasoning behind those failures and look at the skin and put everything together to see if the diet even had an opportunity to make a difference,” she emphasized.

Lastly, veterinarians should talk about the patient’s ears with clients, as many pet owners do not know there is a connection between the ear disease and the skin. However, it is important to “ask questions that are at the level of…clients so [that] they can identify the problems and understand what [is being asked].”¹

“…there's a lot of dogs that will have recurrent ear disease related to food allergies. It can be environmental, of course, but we can miss those if they come in for a skin problem or itching when they're not presenting with ear disease,” said Sheinberg.

Another mistake that Sheinberg has frequently witnessed is having patients undergo a diet trial for the wrong duration of time, whether it be too long or too short. “What I commonly see as a dermatologist…[in]…patients that have undergone a diet [trial] is that the duration of the diet [trial was] wrong,” said Sheinberg. “Maybe they didn't do the diet correctly, but a lot of patients believe they've done a diet trial, but they haven't done it in the right way.”

Because of this, factors relating to owner compliance should be taken into account. These factors include considering whether the home is suitable for the trial (ie., does the home have multiple pets, small children, elderly, owners with inconsistent feeding practices?); whether the owners are willing to change or restrict the dog’s diet; and whether the patient may have access to other food. In these cases, focusing on managing the patient’s symptoms and pursuing an environmental allergy diagnosis may be more appropriate, as a food trial is likely to have a higher failure rate and could result in wasted time, money, and the [the risk of] losing the client.¹ For patients who are undergoing a diet trial, careful monitoring throughout the process is essential.

Takeaway

Prior to even beginning a diet trial, veterinarians must carefully assess the patient’s clinical history to determine whether the patient is a suitable candidate for the trial. Moreover, ensuring proper duration of the trial and considering owner compliance can improve the success of diet trials and save time, money, and help keep the client.

To summarize, the following factors are indicators that a diet trial may be appropriate for a patient, according to Sheinberg¹:

• Non-seasonal canine atopic dermatitis (CAD) cases with skin issues triggered or aggravated by dietary factors
• Young dogs (1 year or younger) presenting with non-seasonal itching, otitis, recurrent pyoderma, Malassezia infections, hot spots, or respiratory symptoms such as sneezing, conjunctivitis, and asthma linked to food consumption
• Older dogs that show CAD symptoms later in life, independent of gastrointestinal factors
• Patients with recurring otitis after other potential causes have been ruled out
• Gastrointestinal markers may comprise recurrent, intermittent or ongoing diarrhea; more than 3 bowel movements per day; grass-eating; belching; borborygmi; vomiting; and gas.
• A history of several diet changes in attempts to alleviate GI symptoms or find a diet the dog can tolerate
• Poor response to traditional treatments

Reference

1. Sheinberg G. Practical aspects and innovations in diet trial for food allergy diagnosis. Presented at: 2025 WVC Annual Conference; Las Vegas, Nevada. March 2-5, 2025.