Is Decon Dangerous For Dogs?

I'm a veterinarian and the most common poisoning by far that we see is when a dog eats rat or mouse poison.  The dog can easily bleed to death (either internally or through the nose, mouth, digestive tract or urinary tract) as a result of eating the poison.  If you catch them within an hour of ingesting it, do give them hydrogen peroxide by mouth (about 1 teaspoon per ten pounds of body weight) to get them to vomit up the poison.  Then get them to a veterinarian as soon as possible.  They will need a vitamin K1 injection (under the skin, NOT in the muscle as someone previously wrote) and monitoring for lack of blood clotting.  Bring along the container of the mouse poison so you can show it to the vet.  Some types of mouse or rat poison can stay active in their system for four to six weeks, so your pet may need to stay on Vitamin K1 capsules for that length of time.  Don't fool around with this, it may cost your dog it's life!

You are right to be concerned.  The chemical of poison in D-Con is brodifacoum. Warfarins are used in both rat and mouse poison products.  This substance is classified as a superwarfarin, which can be highly toxic to dogs, even if they ingest a poisoned rodent.
 
Here are some other common chemicals found in mouse/rat poisons you should be aware of.  Examine the label to determine if these are the active poisons in that product:
 
Strychnine  which is used as a rat, mouse and mole poison. It is  toxic to dogs and a dog may be harmed by eating or ganwing on the rodent who ingested it.
 
Sodium fluroacetate is also a chemical used as a rat poison, and it is mixed with cereal, bran and other rat feeds. It is so potent that cats and dogs can be poisoned just by eating the dead rodent.
 
Zinc phosphide   This substance also is found in rat poisons.  Toxic to dogs and cats also.

Off course Yes. Decon is sort of poison so it will definitely affect a dog as well. Many vets suggest to give hydrogen peroxide to a dog in such a situation, as it  will help them to throw up . Also some vet advise to give Vitamin K injections to help the clotting process.

I have a cat and dog I put out decon and a mouse came out into the house both caught the mouse and had it in their mouth if that mouse had ate decon will it hurt my animals I didnt see any blood on them the mouse got away

Yes it should say on the box of decon to keep away from pets. I am sure it must be dangerious if injested by a mouse and it is eatten by a pet. I don't know if it could kill them but surely they would get ill.