Ahead of this year’s New York Vet Show, we spoke with our 2026 keynote speaker, veterinary internal medicine specialist Dr. Stijn Niessen.

As he prepares to speak at this year’s New York Vet Show, he shares his reflections on what truly matters in clinical practice, where confidence tends to falter in general practice, and why mentorship and community are becoming essential pillars for a thriving veterinary profession. What follows is a conversation that explores not only the medicine, but also the mindset, that shapes better clinicians.

Q: Can you tell me a bit about yourself, your journey to becoming a vet, and what originally drew you to internal medicine? What continues to excite you about the field today?

A: Like many of my colleagues, I've always been intrigued by animals, and playing a role in them leading a healthy life seemed like a really noble cause for me.

When I got more into it, I became attracted to the ‘detective’ element to it. Animals can't speak - and therefore, you need to figure things out by using history taking and physical examination. It resembles a bit of a ‘Sherlock Holmes’ scenario where, bit by bit, you piece it together. I like doing puzzles, and that's actually what I do now on a daily basis. I solve puzzles.

We invite these animals into our home, we receive their love and companionship, and that comes with some responsibility - responsibility to ensure that they lead the healthiest and happiest possible life.
And then when disease does cross their path, you want to be a positive force in trying to manage it in the best possible way to ensure that quality of life is being guarded.

Q: Several of your sessions focus on simplifying complex medical conditions for everyday practice. In general practice, where do you most often see clinicians lose confidence or go off track when managing chronic diseases like diabetes or Cushing’s syndrome?

A: We as a profession are highly educated, intelligent people, and that's not an overstatement. But that sometimes gets in our way - we’re too concerned that we are getting it wrong, and therefore we often get ourselves distracted by lab test results, and they take higher importance in our assessment than they should. They certainly should not overrule our clinical instinct. I would love to empower my colleagues to go back to basics in that regard and make sure that you get the best out of your history and physical examination - trust your gut a little bit more. See all the wonderful diagnostic tests that are available nowadays as a tool, because that's where the success strategy lies: we follow our gut, which is inspired by the physical exam and the history, but we let ourselves be aided by the diagnostics.

When you're talking about diabetes or Cushing's, that's extremely relevant. We can be easily distracted by all kinds of glucose curves in diabetics or by all kinds of cortisol values in the dog with Cushing's. But those values go up and down all the time. Cortisol is a stress hormone. Trying to make big treatment decisions on the basis of a parameter that is so fragile and so dynamic is not the right way forward. Whereas looking at the bigger clinical picture should be the starting point.

Q: Your lecture on diagnostic tests asks which tests actually provide “bang for your buck.” How can veterinarians make smarter decisions about diagnostics without compromising patient care?

A: Vets are scientists, and as scientists, we get reassured by numbers, because that provides a level of certainty about what's true and what's not true. When we're presented with an animal, it's uncertain what this animal is suffering from. Therefore, there's a real human tendency to try and grab the ‘certainty’ from those laboratory tests. We as clinicians need to have a think about what truly can be learned from each diagnostic test and which ones are going to change the management. And instead of doing a big fishing expedition where we throw out a net with all kinds of tests, radiographs, bloods, we are better off targeting our diagnostic plan to actual problems found in our history and physical examination.

One of the things I'll be emphasising to our colleagues is to go back to basics rather than relying too much on diagnostic tests, and only run that test when it actually will be anticipated to change your management of the case. With some diagnostic tests, if we run them in a blanket way, like throwing out a net, they perform as well as flipping a coin. That’s not good practice for our patients or their owners.

We as vets are the liaison between the science and the owner of the pet.

Q: One of your sessions is entitled “Canine Cushing’s syndrome made simple.” What are the most common misconceptions you see among clinicians that drive you to speak about this disease at NY Vet?

A: Many colleagues are scared of Cushing's. They're scared to misdiagnose it, and they're scared to manage it. I would love to turn that around and I would love for people to feel empowered to make a large part of the diagnosis without diagnostic tests. Cushing's is a syndrome, which means it's a collection of clinical signs that you can pick up in your physical exam and in your history. So, a large part of the diagnosis is already made prior to us picking a diagnostic test. I want people to feel empowered that they can do so, rather than feel lack of confidence and then seeking the confidence from a test. I want vets to realise that they are themselves the key to a confident diagnosis.

In terms of management, lots of vets are scared of treating Cushing's and they are especially scared of using trilostane, a drug that is being used for the treatment of Cushing's. And I want to make clear to them that actually their ability to do harm with trilostane is extremely limited.

It is true that some dogs have an idiosyncratic reaction to trilostane, which means you can't predict it, but it's not dose related - it's tough luck. However, that should never stand in the way of trying to treat. Quality of life is low in untreated Cushing's. It is my duty as a vet to tackle this, to advocate treatment. There is always a risk involved with some of these animals having an unpredictable reaction, but that's the case with any drug. It cannot stand in the way of us starting treatment, because by not daring to diagnose Cushing's and by not daring to treat Cushing's, we actually cause suffering, and that's against our oath. I would love for people to become confident in trusting the clinical picture and trusting that they are doing the right thing by tackling that disease rather than running away from it because we feel uncomfortable.

Q: What is the core clinical "pearl of wisdom" or mindset you'd like delegates to walk away with after your sessions at New York Vet Show this year?

A: Realise that your value as a veterinarian is your brain and your personality and your values.

That’s really what pet owners are looking for as well. They're not looking for someone who just runs tests or who is vague about what might or might not be going on there. They're looking for an actual person they can relate to, who is at times vulnerable about what they don't know. By adopting that and showing your values to your clientele, you're going to be an enormously popular veterinarian.

And it will prevent lots of issues with misunderstandings with the owners of your patient population. And it comes back once again to having belief in your initial assessment of the case. I think trusting our initial assessment of the case and relating that back to the client in an empathetic, value-based manner is the way forward for our profession.

Q: Alongside your clinical and research work, you’re involved in initiatives like the Virtual Veterinary Internship through Veterinary Information Network. Why is mentorship becoming increasingly important for veterinary professionals today?

A: We tend to be high achievers. We tend to be very critical, but we also tend to be very empathetic - because why else would we take it upon us to spend our life to stand up for those without a voice? So, we're very sensitive on average. Sometimes, the veterinary environment can be rather harsh because we need to make money to make a practise survive and sometimes also to please those above us. And some clients just want you to solve everything for no money within no time, which is unrealistic. As human beings, we take responsibility for problems that we can't solve. That makes it tough to feel comfortable thriving, and therefore, being alone means that we find ourselves to be self-critical people. The solution is to make sure that we always surround ourselves with a community of people where we share those difficulties with each other and also share experiences. Everyone should have at least one mentor with whom they can discuss those difficulties. It’s important to have a role model and a mentor at the very beginning of our career. This is why we came up with the Virtual Veterinary Internship, which is a clinical and non-clinical mentorship program that provides support after vet school, after a career break, or whenever one feels stuck in one’s current environment and wants a vehicle for growth without leaving their current job.

Q: You’ve worked extensively in research, referral medicine, and teaching around the world. What are you most looking forward to about speaking with the US veterinary community at the New York Vet Show this year?

A: I've got a lot of colleagues and friends over in the US. I'm also a consultant for the Veterinary Information Network. On a daily basis, I speak to colleagues in the US and try to help them with their cases, but many of them are mere names on a screen. I’m excited to attach faces to those names and get to know them in person as well. What I'm also looking forward to is once again being a voice and a personification of a colleague who might have a different accent, who might be coming from a different part of the world, but who actually is exactly the same as anyone else in the US. We live in worlds where differences are exaggerated. I would love to see the veterinary profession shield itself from the polarising forces that are at play in the global level. Hopefully we can enjoy unification and see the commonalities, of which there are so many, during the Vet Show. So, let’s grab a beer!