I tend to agree with Betta. While it's an intriguing thought and likely useful to consider from this perspective, I don't think it's the whole story.
Last night I saw a piece of a show on PBS--Scientific Investigators maybe?--that theorized the die-off of frogs in the Eastern US is being caused by a fungal-related disease. The fungus appears to block the ability to breathe through their skin, which kills them.
Can frogs be carrying emotional baggage that suppresses their immune system as Andreas suggests?
The concern put forth by this show is that because frogs are anatomically very similar to humans, it may be an early warning of unexplained environmental damage.