It's not uncommon for this question to remain unanswered even after someone claims to have authoritatively answered it. The problem is our lack of any real science behind it.

The two most common answers are:
Yes - but symptoms are not the same as human infection
No - animals are immune

We've all heard enough about H5N1 to understand that a mutating virus can hop species. Not familiar with H5N1? The Bird flu site will get you up to speed. It's not zombie related, but does provide a primer on how viruses spread, mutate, are tracked, emerge, and then go dormant.

I believe that any kind of zombie infection would also mutate. Frankly, it would have no choice as the living in an area decreased with it's own proliferation.

vanrulzz -I really doubt that it will spread to animals, or we would all be dead instantly (zombie insects, zombie fleas, zombie dogs, zombie charging rhinos....) and after all the Zombie Survival Guide (i guess its our bible here) says Humans Only.

TonyPro --Cross-species infection is seen only in a small portion of known viral strains. And in those that can be transmitted from animals to humans, drastic changes frequently take place (for example, in the book I Am Legend, the main character is bitten by a bat that is infected with the zombie germ. Instead of becoming infected, he becomes immune because the bacillus had been so weakened by the bat's immune system). It is more likely, were the infection to maintain its zombifying properties when transferred to another specie, that it is a bacterium, rather than a virus. The Bubonic Plague is an example of the effectiveness and devastation a bacillus bacterium can cause. So unless this is the case, I believe there is little to fear regarding a viral infection being transmitted by animals.


Toomin: It's possible that the virus (if it's a virus) could cross species and infect animals as well as humans. However just because it could infect animals and humans, it doesn't mean it would be able to take over every animal. So while it is likely that it would be able to move from humans to maybe apes or even other mammals. The virus may not be equipped or be able to mutate enough to infect reptiles or insects. However even if the virus were able to infect insects like tics, flies and fleas, if one were to ride out the infection 'storm' in a wintry domain, bugs would not be a problem.

Despite my arguments, I do agree with the Guide, I think it would be an unlikely scenario that the virus would cross species.

ZEROFLY: Although the virus can be transfered over to animals, they cannot be reanimated. The animal in question becomes infected and dies sooner than a human would, too soon for the virus to make the change. It remains in the bloodstream and doesn't get the time it needs to affect the brain in the way it does in humans. Even with that, animals are smart and avoid the undead, and not only that, the undead will take no notice of any animal around if a person is there instead.

DevilMayCrye: I think it could spread to other species, but they would act like a "Typhoid Mary". They could carry the disease/virus/parasite/whatever, but not be affected by it.

McSkullcracken: I believe that whether it is a bacteria or a virus the infection could infect humans and animals. This does not mean, however, that the infected animals would "reanimate". As has been suggested in The Zombie Survival Guide, the infection may not be able to convert the brains of animals due to their smaller size or because of genetic differences (both really, I'm sure whales and other large creatures have larger brains). While I personally deem unlikely to the point of near impossibility, it may be that the infection could "reanimate" species besides humans. But a reanimated animal would not necessarily behave in the same manner as a reanimated human. They may have a compulsion to mate rather than consume, or to keep moving, or to simply sit/stand there until they waste away. Again, even if cross-species infection is possible, it would not mean the same reaction/symptoms.

Shadow Five: I can only hope with all my heart that the viral nightmare that keeps us up at night cannon cross species lines. If it can, I give our collective civilization less time on the earth than the half-life of a not-so-stable isotope.

Z13: The chances of the virus effecting animals as well as humans is extremely high. If its a virus of that substantial proportions, the limits for it expand beyond anything I can imagine. We could have mutonogenic creatures that were once animals become our greatest nightmare. What if the virus enhances the speed and strength of a rhino? Or a cheetah? What if it raises the size of the animal and makes them more violent. What if all the bugs in the world become 5 feet tall? Beetles would rule the world.

Gladimnotdaonly1: I've been thinking on universal balances. If human zombies arise, I believe some animals will also carry it. There's a lot of research behind my thoughts, I've compiled composition notebooks on different viruses, bacterium, immune deficiencies, and parasites. It's all in hopes of having every possible angle on zombies before it happens. As McSkullcracken said the infected animal would probably be affected differently. I don't believe it would be a mating urge, could be though. Like a dog can eat things that we can't, without getting sick. So an infected dog might be able to have it's own immunity to a virus. Parasites would be my main worry when it comes to a cross species hop.

Kingrich3: Face it, if it does hop to animal's there's no point in any planing. I mean hordes of zombie fleas? you're screwed, and what if it jumps to bacteria. no matter where you go, no matter what you do, the bacteria will just infect you, the world would be infected within hours

Irishflyboy254: I think we are all forgetting the possibility of a man-made viral agent, similar to Resident Evils T-Virus. While far fetched, it stands to reason that there is a distinct possibility that such an agent could make he species leap. The only saving grace would be that eventually an immunity would form to such a disease. But that would take decades, and the world we be overrun.

Tactics101: Everyone remember The Black Plague or Bubonic Plague? So of course cross-species transmission is possible

Apocalypsewillcome: If zombies did infect mice or rats or anything like that then I'd be screwed! There's like a million rats in the fields next to my house! :P

StrykerPez: Look at rabies. Dogs, cats, rodents, humans... However, I think that the virus would have to target a specific part of the human brain and therefore only be carried in other mammals. A dog infected with the Z-virus would show no signs of infection, yet if the dog bit a human, then the human would turn.

Renegade13: I basicly think the same as StrykerPez the animals can carry but will not turn.

Dooran: While it is possible for the zombie virus (as it seems is the most probable cause) could in theory go cross-species, there is one point to consider: Zombies hunt people. That is the generic consideration taken, that zombies will hunt down other humans, in a cnnibalistic fashion. Could it not be said then, that a zombie dog would hunt down other dogs? Or cats with cats? They may or may not have any intrest in humans at all.

ReverantFaun:Well seeing as how we humans don't have the strongest immune system in the animal kingdom but we aren't the most prone to disease either then there are two possibilities:

One

Any animal could just as easily die from being bit, or could become zombified

Two

We have just the right/wrong type of immune system that allows us to to be zombified

We wouldn't be able to tell untill it happens i guess




See also:

• Deteriorating tissue impacts
• First Signs of a zombie bite
• First signs of a zombie outbreak
  
• Why hunt the living?
• Motor Skills
• Possibility of "recovery"
• Psychological effects on the living
• Experimentations
  
• Origin of the Zombie
• How are zombies created?
• How a zombie virus could arise
  
• Celestial Events

karaz: well if that was true i still say we'd all be dead zombie bugs just think about that zombie bugs that in my mind is hell though i think the zombies will eat anything that moves