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Editor's Note

Fear: Physical Effects in Our Patients?



Lesley G. King, MVB, Diplomate ACVECC & ACVIM (Small Animal Internal Medicine), University of Pennsylvania

Dr. Marty Becker’s interview for The Back Page column of this issue reminds us about the Fear Free initiative, which has been gathering momentum over the last few years. This concept prompts many questions. Of course, we all want to have happy, fearless pets visiting our clinics. Our job would be much easier if our patients always greeted us with wagging tails, or climbed out of their carriers purring and “making biscuits.”

When I initially read Dr. Becker’s interview, I thought: Yes, from a humane perspective, we would like our patients to experience minimal fear or anxiety, and from a business perspective, we will likely retain clients if their pets are calm and happy when they come to our clinics. But, I wondered, does transient fear (even if it is severe) really have adverse physical effects? How could it cause or contribute to somatic illness?

In fact, proponents of the Fear Free initiative make an important point. Physical injury CAN occasionally occur as an unintended consequence of fear in the veterinary clinic. Think about animals that are so fearful they require restraint for routine procedures, such as vaccine administration or even a physical examination. If these animals struggle, even gentle restraint can lead to proptosed eyes in brachycephalic breeds, ruptured cruciates in Cushingoid dogs, or fractures in rabbits.


I have seen healthy puppies develop life-threatening neurogenic pulmonary edema following restraint for minor procedures, such as vaccine administration or ear cleaning. In these susceptible animals—puppies seem to be more susceptible than adult dogs—even a minor or transient episode of inadvertent airway obstruction can trigger a brainstem reflex, resulting in acute pulmonary edema. Edema is typically caudodorsal in distribution, can be mild to fulminating, and, in severe cases, can lead to respiratory distress and, sometimes, death within hours.


Adverse physical consequences of fear can be very serious in animals with pre-existing disease. Fear and anxiety cause sudden release of stress hormones, such as cortisol and catecholamines as part of the “fight or flight” response. We’re familiar with the metabolic effects of these stress hormones when we attempt to measure in-hospital blood glucose curves in stressed diabetic patients. When combined with fear- or excitement-driven cerebral input, these hormones can cause even more trouble in animals with borderline lung function, who can experience worsening dyspnea and desaturation due to increased oxygen demands.


Consider previously stable dogs with partial upper airway obstruction due to brachycephalic syndrome or laryngeal paralysis, placed in a high stress situation, such as a visit to the veterinary hospital. With increased respiratory drive, deep inspiratory efforts against a partial airway obstruction cause further collapse of the upper airway, creating a vicious cycle of worsening obstruction that can result in cyanosis, hyperthermia, and disseminated intravascular coagulation. These animals can decompensate and develop severe respiratory distress within 20 to 30 minutes after arrival at the hospital.


Acute stress hormone release can also lead to adverse effects on the cardiovascular system, which can be a real problem in animals with pre-existing or undiagnosed disease. For example, acute release of catecholamines and cortisol in an already hypertensive cat can lead to sudden severe worsening of hypertension, which could result in acute retinal hemorrhage or detachment, or even an intracranial hemorrhage.

Acute fear or stress can worsen heart failure or trigger arrhythmias, which both, at their worst, could cause sudden death. We’re all familiar with the challenges of diagnosing cardiac disease in cats: those that have murmurs on auscultation don’t always have significant heart disease, and those that don’t have a murmur or a gallop can sometimes have severe cardiac abnormalities. There is much to worry about when faced with the need to restrain a fearful, fragile, fractious cat.


So, I’m a convert! We should embrace the concept of Fear Free because a lifetime of happy veterinary visits may help protect our patients from vet-visit-induced health crises in the future. Application of the simple concepts of the Fear Free initiative allows us to lay the groundwork with those pets as they grow up with us.

—Lesley King, Editor in Chief