It seems that the increasing responsibilities and pressures of operating his "Mega-Bucks Animal Hospital" have taken away the precious hours of spare time that Arnie used to spend pursuing his former hobby, bird watching.

However, being a trained observer and resourceful opportunist, he soon discovered a new pastime, veterinary-client taxonomy.

We all encounter the behavioral type known as the Free Roaming Hall Stander (Nomissa thingum). A good example from my practice would be Mr. Gooseneck. He is either just a plain busybody or perhaps suffers from exam-room claustrophobia. At any rate, soon after he is left in the exam room, you will find him standing in the hall.

Though he doesn't stray very far, his dog roams the extent of its 9-foot leash, thereby creating a hallway obstacle course while simultaneously coughing on and contaminating everything in sight. Mr. G tries to strike up a conversation with anyone or anything that acknowledges his existence. He tells everybody his favorite dog stories and offers his own diagnosis to any other client he might contact. Often, he will stay in the waiting room for 20 or 30 minutes after we send him home just so he can enjoy the company of other dog owners.

Another common client behavioral type is the Sterilization Vigilante (Fixum mustus). Gerta Stoppit comes to mind. She is a volunteer storm trooper for a local organization called "Gonads-gotta-go." Whenever she comes to the office she gives an impromptu waiting-room lecture on animal birth control. Any client with a pregnant animal is in for a real brow-beating.

Her goals are admirable, but her overzealous pursuit of anyone with an unspayed animal can be a bit too much. If she gets wind of a person who has such a pet, she'll track them down with more tenacity than the Royal Canadian Mounted Police.

When it comes to sheer amusement, you can't beat the client type known as The Last Minute Dog Trainer (Commandus futilus). We each encounter this subspecies on a regular basis. When told to put the dog on the exam table, he starts shouting a litany of commands:

"Up boy!"

"Up now!"

"Jump up, Barkey!"

The dog, of course, ignores all attempts at verbal communication. Throughout the office call, this man continues to yelp commands. "Sit!" "Stay." "Hold still." The pooch pretends to be deaf.

Often, I want to blurt out a command of my own, "Shut up!" But I rarely give in to the temptation.

Finally, I need to mention my least favorite client type. It is the Deadbeat (Swift running thump-mortis). Although there are several subspecies included in this group, they all have one common trait: They leave a distinctive trail often characterized by growing numbers in accounts receivable. Other notable features may include empty checkbooks, incomplete addresses and broken promises.

Unfortunately, the thump-mortis often is difficult to recognize until after he or she has left the office. Then they become impossible to track down. Collection agencies often cannot locate them, and private detectives are expensive.

Recently, however, we hatched a plan to catch our most elusive Swift running thump-mortis. We leaked information to Gerta Stoppit that this client owned an unspayed mongrel dog.

She had him cornered before the motor on the U-Haul had a chance to cool off.

Dr. Obenski owns Allentown Clinic for Cats in Allentown, Pa.