By Mary Wesker, Courtesy of Ferret-World. Full article is here and I strongly recommend everyone read it. 

Excerpts from the article (an attempt at a tl;dr): 

Ferrets and Other Animals:

Stef’s article reads: 

“No, ferrets don’t get along with other animals. There are a few exceptions, and even these need to be managed carefully. There are a number of factors which cause problems. Ferrets are natural predators and rodents are their natural prey. Never expose your rodent to a ferret. But birds, fish, reptiles, and many other animals are also at risk when kept around ferrets.”

“...Dogs vary in size and temperament which means while many dogs won’t make a good companion for a ferret, a few will.... Big dogs are less likely to intentionally hurt a ferret, but pose a risk of accidentally injuring them, or intentionally hurting them when toys or food is involved.”

I WANT EVERYONE TO READ THIS NEXT BIT. Safety is more important than aesthetic!

“Maybe the first thing you need to ask yourself is why you want to introduce your ferret to another animal. Is it for the ferret’s benefit, or is it for the cute factor of them getting along? If you want to give your ferret company, the very best choice is another ferret. They can be very social animals and already understand their unusual and aggressive form of play...However, it is also important to understand that some ferrets simply won’t get along with other ferrets and making them live together can cause great stress, that can lead to health problems. Some ferrets are simply solitary.”

“...Because your pets can’t talk, you need to learn how to read their other signals like noises and body language. Always keep in mind that they are not human and some actions by an animal don’t mean what they would if a human did them. We show our teeth when we smile. Baring teeth rarely means an animal is happy. But there are other signals that can be misinterpreted as well. A dog staring fixedly at a ferret and wagging its tail looks like it wants to be friends. But instead it might be happy because it is just about to get a little animal to hunt. Be aware of your ability to misinterpret signals and learn as much as you can first.”

Stef continues: “Once you’ve successfully introduced your ferret to another animal, there is still work to do. Even though they might get along really well in your presence, some dogs might attack the ferret when you are not around. And while the stakes are low, friendship can come easily. But when toys and food get involved the mood can change too suddenly for you to intervene. Always feed them separately and pay attention to dog toys that might cause territorial behaviour.”

Here’s yet another important tidbit I see MANY owners ignoring: “Some diseases [Mary’s note: read: rabies, and canine distemper] and many parasites like ticks and fleas can jump the species barrier. Animals that get free time roaming outside are more likely to introduce parasites and diseases than those that have lived a protected life inside. If you’re going to let your ferret build a friendship with an adventurer, make sure you keep your other pet’s vaccinations and health at a high standard as well.”

All in all, I agree with Stef’s article. As a long time owner and trainer of several animals (dogs, horses, cats, reptiles, amphibians, various rodents) I am familiar with people and their desire to “make their animals be friends” but that’s risky and irresponsible at best in 9 situations out of 10. I am going to include my original comment to the blowback this article got, and invite other admins to let me know if they would like me to include their comments on this topic as well. NOBODY, not even Stef in her article, is saying ferrets can never co-exist with other animals; they certainly can, but some common sense precautions should be taken and you should NEVER try to force animals to co-exist, nor should you ever forget THESE ANIMALS ARE PREDATORS, and some are much larger than ferrets. It is not worth a dead ferret or injured dog or cat, to try to make them “friends”. Can some peacefully coexist? Of course. But they should never be left unsupervised, nor should responsible owners forget where these animals come from and what is instinctual for predators (nor the common sense aspect of “cats can be sharp and points and aggressive, and big dogs can accidentally step on a small ferret and break their back”.)

My original comment to the original shared article in the group: 

“The point that needs to be made here, is a point I personally make ALL the time; ferrets are small. They're smaller than most cats and certainly most dogs, and they weigh less than each 9 times out of 10. For that reason alone, ignoring that cats and dogs have prey drives (and ferrets do also), I as a long time animal owner and animal trainer (both of various animals), will NEVER recommend encouraging your ferrets to be "friends" with larger animals; predator OR prey. Worst case scenario; the ferret gets injured by the cat or dog, and it only takes ONE accident, or the ferret kills a smaller animal, they're both predator and prey and designed to kill small animals. That is the general feeling among admins here; all of us have either experienced a close call with a ferret and another animal, or heard countless stories of ferrets and other animals being killed and injured. 

Ferrets do best with their own kind; and that's how it should stay for the safety of ALL involved. 

Your ferret and dog/cat are "friends"? Great, but being "friends" (which is not a common thing cross species with animals; and its usually people anthropomorphizing them, as we're apt to do) doesn't mean your cat with big claws and teeth, or your 50+ pound dog, won't accidentally bite too hard, scratch too hard, or step on the small ferret someday. Or that your ferret won't latch onto your cat or dog and cause unnecessary pain and damage. Expensive damage.

People need to remember this, as well as that this group exists, first and foremost, as an educational tool. We will ALWAYS act in the best interest of the ferrets, regardless of people's feelings on our advice. People wanna take risks with animals? That's their business, but we don't encourage or allow discussion of dangerous (OR potentially dangerous) practices here. Yes, this article's title could have been worded better, but it's a good educational resource written by someone with a wealth of ferret knowledge.”

By Holly

Ferrets should NEVER INTERACT WITH PREY ANIMALS. Ferrets have strong instincts and high prey drives, and even if they are the most docile Marshall's ferret who's never been outside or seen another rat/rabbit/etc in their life, they can VERY quickly kill them. The rats/etc will be in a constant state of panic because they'll see, hear and smell their predators. Just because you don't see them acting scared they will always be on guard in there home. Which is not how I like to feel when I want to go to sleep. 

Scientific study about ferret-smell stressing out rats

Birds are the same. On top of that, mammals have a gram negative bacteria in their saliva which is lethal to birds. It's a specific type of bacteria mammals have and are equipped to handle, but birds are not, and thus cannot fight it off properly. The name "gram negative" is from a staining test developed by Gram, those bacteria cells don't retain a dye used during that testing.

Anecdote: My docile Marshall's boys who were complete sweethearts were introduced to my roommate's giant rabbit. Within minutes, they were both swarming the rabbit and ripping out it's fur, like big football dudes swarming in on a defenseless nerd. It was STARTLING. The rabbit was stress-pooing with every step (it was litter trained normally). We separated them fast... I'm glad nothing came of it, and now I've learned and know better.