A fish that knows the way to go: the Chinook salmon, which appears to use the Earth's magnetic field to navigate ocean waters and rivers. Jeff T. Green/Getty Images hide caption

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The sexually transmitted cancer is common in street dogs around the world. Noel Celis/AFP/Getty Images hide caption

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Jerky treats for dogs and cats have been linked to pet illnesses and deaths. But it's still unclear what is causing the problems. iStockphoto.com hide caption

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If you need empirical information about what is happening in the brain of a dog to know that dogs think, then either you've never met a dog or your own humanity is in doubt. iStockphoto.com hide caption

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