An Interview with... Dr. Ad Rijnberk


Even in this age of evidence-based medicine, case reports still have great value, says this professor, researcher, and veterinary endocrinologist. "It is the well-worked-up case report that may provide completely new ideas."

Ad Rijnberk, DVM, PhD, DDr.hc, DECVIM-CA, HonAssMRCVS, is professor emeritus of internal medicine of companion animals at Utrecht University in the Netherlands. His research has concentrated on clinical endocrinology of companion animals.

What are the most exciting changes you've seen in veterinary medicine?

The elucidation of many mechanisms of disease and the improvement in patient care by increasingly making use of the best available evidence-based medicine.

Who was your most memorable patient?

Wanda, a dog brought to the clinic with features of body enlargement. The owner, a family doctor, thought the signs could be due to pulmonary hypertrophic osteoarthropathy; it turned out that Wanda had excess growth hormone (i.e. acromegaly).1 This case was the starting point of several years of research, providing insight that in this and similar cases the growth hormone excess was not of pituitary origin. The research revealed that dogs and cats produce growth hormone in the mammary gland under the influence of endogenous and exogenous progestins. In dogs, this mammary growth hormone may reach the systemic circulation and give rise to acromegalic changes and insulin resistance.

In this context, what value do you place on case reports?

Several of my memorable cases have been written up as case reports. Some of these were reports on a newly recognized disease, a disease variant, or a disease mechanism. Case reports have been the subject of some questioning. They have been given a second-class status with the remark that they are only uncontrolled, n = 1 experiments or records of rarities. However, in my experience, it is the well-worked-up case report that may provide completely new ideas. In evidence-based medicine, the randomized trial is on top for strength of evidence. It is used for evaluation of medical interventions in which there is uncertainty about a benefit. This is in itself not very striking. Epidemiologists agree that these trials bring final quantification, but they offer little scientific novelty. For true intellectual advancement in medicine, the case report and case series are on top.2

Where have you found inspiration throughout your career?

Looking back, I think my work has been driven by feelings of dissatisfaction with unknown mechanisms of disease and inadequate diagnostic procedures. Phrased more positively, it has been scientific curiosity that has motivated my clinical research. In cooperation with many people, I have tried to solve some of these problems and answer these questions. For many years, I have had the pleasure of working with highly dedicated and competent people who are a continuous inspiration.

What books have been helpful?

I found support by reading the work of science philosopher Karl R. Popper, who in the 1930s and 1940s introduced the principle of striving for falsification of theories rather than looking for confirmation of theories. The central question in science is not how probable truth can best be found but how untruth can best be revealed and eliminated.

Another writer who was of great help and inspiration is Henrik R. Wulff. I learned a lot about elementary principles of clinical thinking and research from his books Rational Diagnosisand Treatment and Philosophy of Medicine: An Introduction.

What do you consider a threat to the quality of the work of the veterinary profession?

Unlike in human medicine, our patient population comprises several domestic species with differences in anatomy, physiology, and pathology. In addition, we are supposed to cover other areas such as veterinary public health, laboratory-animal medicine, and wildlife health. Against the background of this wide spectrum of disciplines in veterinary science, it is somewhat amazing that veterinary faculties at most universities are quite small. Often the critical mass of staff needed to cover the areas with sufficient depth is not met. Fortunately, in some countries the teaching institutions and the competent authorities are beginning to realize that cooperation or merger of faculties may be needed.

Should students have to learn about all the fields of veterinary medicine?

Most veterinary curricula aim at graduates being omnicompetent veterinarians. Several areas can only be touched superficially. To alleviate the teaching load and to improve the competence of a graduate in a limited area of the broad spectrum, tracking has been introduced at some universities. The students can choose, for instance, either farm-animal, equine, or companion-animal medicine. The ultimate and, in my opinion, most desirable form of tracking is to allow students to choose their area of interest when entering veterinary school. However, the core of veterinary education should remain comparative pathobiology, as all disciplines of veterinary medicine stem from it.

Are you a cat or a dog person?

Initially I was fonder of dogs than cats. Over the years, I have learned to appreciate the special characteristics of cats. It has also been a pleasure to see that in the last two decades studies in cats have revealed several newly recognized clinical entities.


1. Rijnberk A, Eigenmann JE, Belshaw BE, et al. Acromegaly associated with transient overproduction of growth hormone in a dog. J Am Vet Med Assoc 1980;177:534-537.

2. Vandenbroucke JP. Case reports in an evidence-based world. J R Soc Med 1999;92:159-163.

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