An animal in pain is more likely to bite. So muzzle it first with a scarf, belt, or towel, unless it’s vomiting. Get the animal off the road by gently sliding it onto a towel or blanket (these should be in your car's first-aid kit). Don't lift the animal. Make sure it’s warm, as it may be in shock. If it seems to have any broken bones, do your best to not move it too much.
Many household items can be dangerous to dogs and cats -- everything from antifreeze, insecticides, and aspirin to raisins and sugar-free gum. But don't panic. Many of these have antidotes. Call the Animal Poison Control hotline at 888-426-4435 or the Pet Poison Helpline at 800-213-6680 immediately. They can probably help you even before you get to the vet. (Understand, however that there is a fee for the advice.)
If your pet is unconscious, open its mouth and try to clear the object out with your fingers. If the animal is conscious, do a modified Heimlich maneuver. Place the pet on its side, applying pressure right behind the ribs and pressing your hands forward. This may help push the item out. Get someone else to drive to the vet so you can continue to do this on the way.
A seizure will generally pass on its own in less than 3 minutes. Your job is to make sure the animal is safe while it's happening. Get any movable furniture away from the pet. Don't put your hands or your face near the animal's mouth, and don't pull its tongue out of the mouth. When the seizure is over, contact your vet.