Apply a non-adherent pad such as telfa or gauze sponges to the wound. If the wound is actively bleeding apply direct pressure to the wound in an attempt to stop the bleeding.
DO NOT remove any blood soaked gauze or pads from the wound. If they soak through apply additional layers on top.
Loosely wrap affected area with cast padding or long narrow strips of cloth.
Apply a layer of roll gauze over the padding. This layer should be applied tightly but if you cannot pass a finger under the bandage it is too tight.
Apply a layer of cohesive bandage material such as Coban or Vet-wrap or a loose layer of first aid tape over the gauze layer to complete the bandage.
You should be able pass a finger underneath the top edge of the bandage. If you cannot it is too tight.
Bring your pet in to your veterinarian for medical care.