In an ideal world, the home owner is able to remove the pets prior to showings. In a realistic world, the home owner must be home with the pets for showing, take them for a walk during showings, or leave the pets in the property for showings.  As Realtors, we must be responsible for the property and its inhabitants!

Pets should be away - the best way.

Make arrangements with the seller with regard to pets.  If needed, the listing agent should be present at showings to manage pets.  

I feel very uncomfortable hoping that showing agents and their prospective buyers will be as careful with pets as they need to be.  They're distracted because they're deciding whether or not the house is the one they want to buy.

The pets should be off the property when the home is shown.

Frank Rubi - no pets while showing the property or at the open house! Period.

Cindy nailed this one!

Chief Cook always advises that pets of the dog, cat, rabbit or larger critter variety either be removed from the property during showings and opens or crated and/or contained.  Iguanas, lizards and birds, etc. should be similarly contained. 

Thanks Frank Rubi, MBA!

I always encourage Sellers to remove their pets.  It is very stressful to pets to have someone in their home and removing them removes a great deal of liability on the Seller's part.  I do not schedule showings if the pet is in the home.  Keeps everyone safe.