A few weeks ago a client showed up at my office at 6:20 a.m. with a cat carrier. She advised me that inside the carrier was a legendary cat — legendary among veterinarians, that is, for being a challenging patient. The cat generally couldn’t be examined or handled at vets’ offices without sedation.

Once one has received such a warning, it is a very bad idea to reach into the cat carrier. One is likely to suffer significant bodily harm if one approaches such a cat from the front. A veterinary technician and I closed all of the doors in the hospital to shut off escape routes. We unscrewed the bolts that held the carrier together and lifted off the top. We beheld a cat who clearly was in trouble.

First, she barely struggled against my attempt to evaluate her. I was not able to perform a very thorough oral exam on her, but she tolerated the rest of the exam, including measurement of her temperature. She was profoundly dehydrated. Her coat was unkempt — this is a subtle sign of illness in cats, which develops as they become too lethargic to groom themselves properly. She looked like she had been losing weight rapidly and recently. Her intestines felt thickened when I palpated them, and no food could be felt within her digestive tract.

The owner advised me that the cat had been sick for three days. There had been vomiting and diarrhea, and the symptoms had progressed to the point that there was substantial blood in the stool. Why, you may wonder, did she wait so long to take the cat to the vet?

In fact, she did not intend to wait. This was a diligent and responsible cat owner, but the cat had outmaneuvered her. She had spent the past three days desperately trying to catch the cat and get it into the carrier. She had applied a number of tricks. She tried to lure the cat into the carrier with food and treats, but because the cat had no appetite, this didn’t work. She had attempted to sneak the cat into the carrier after petting her for a period of time, but the cat struggled and got away. The owner had come close to corralling the cat on several occasions, but a battle royale had ensued each time. And each time the cat had won.

The owner felt horrible, and ashamed, that it had taken so long. She was very worried that the delay would compromise the outcome of the case. She felt like it would be her fault if the cat did not recover.

In fact, the cat did recover. But if she hadn’t, it would have been nobody’s fault. There is no shame in being unable to catch your cat and put it into a carrier. It happens all the time.

My current office sees only emergencies, so we don’t take appointments. For many years, however, I was in a general practice where appointments were the norm. I would estimate that appointment cancellations because an owner couldn’t catch a cat occurred at least once weekly.

The phenomenon is based on many principles. Many cats have an almost preternatural sense for what they perceive as mischief on the part of the owner. They are very good at picking up on clues that a vet visit may be in the offing. Owners have told me of cats who would disappear for a week when they caught sight of the carrier, or even saw the owner at the door of the closet that held the carrier.

Cats’ natural physical abilities also are phenomenal. The average house cat can run, for a short time, faster than an Olympic sprinter. She can turn and dodge better than any human. She can jump to out-of-reach heights, and squeeze into areas that are inaccessible to humans. If such a creature is determined not to be caught, it will take almost superhuman abilities to lay hands on her.

Once the cat is caught, of course, the struggle is not over. She must be placed into the carrier. She will be constantly vigilant for an escape opportunity. She may splay her legs so that she cannot fit through the door. She may dig in her nails to try to struggle out before the door is closed.

And if she becomes desperate enough, she may resort to violence. Cats are armed to the hilt with sharp claws and teeth. Their reflexes are super fast, and they know how to use their weapons. If a cat does not want to be held, no owner will be able to hold on.

In fact, no person can hold onto a cat who has become determined to be let go. There is no amount of training that will make a person competent to hold on to such a cat. There is no trick that will prevent injury to a person who makes the mistake of holding onto a cat who has become markedly fractious.

In fact, learning when to let go of a cat is a milestone one must achieve before one can be considered an expert cat handler. When a cat really wants to be let go, one of two things will happen. It will be let go immediately, or it will maul the person holding on and then will be let go.

There are few things I dislike more than watching the spectacle that occurs when a cat novice fails to let go of such a cat. There is something sublime and horrible about the facial expressions such people make as they watch, incredulous at first, the cat tear apart their hand and arm while everyone in the room yells at them to let go. Holding on longer only causes greater injury, with the same final result in every case: The cat is let go.

Once such a cat is loose, closed doors will confine her to a safe area, and a soft net may be used to catch her safely. Tranquilizers subsequently can be administered to the cat to lower the stress level for all involved.

A cat owner who cannot get his or her pet into the carrier should feel no shame or guilt. Cats’ ability to stay out of carriers speaks to their amazingness in general.

The cat who showed up at 6:20 a.m., I am happy to say, responded very well to treatment. By the next day she was feeling much better. Without sedation, no human being could have gotten her into the carrier for the car ride home.

Read more on cats, fear, and carriers:

• 5 Tips for Making Your Cat Carrier a Happy Place for Kitty
• 7 Ways I Help My Cat Avoid Fear of Visiting the Vet
• How to Get Your Cat into a Carrier

Got a question for Dr. Barchas? Ask our vet in the comments below and your topic might be featured in an upcoming column. (Note that if you have an emergency situation, please see your own vet immediately!)