11. GiardiaGiardia in puppies can be difficult to diagnose and is a common cause of puppy diarrhea. Learn more about this potentially devastating protozoan parasite in this article about giardia in puppies.
12. CoccidiaSome intestinal puppy parasites are so tiny, it requires a microscope to find them--but they can still cause great health problems. Coccidia is a protozoan as is giardia, and both can be contracted from the environment. Learn about the signs, diagnosis and prevention for the disease in this article about coccidia in puppies.
Donald ie TBone Kershner/Flickr
Salmonella is a bacteria that has been known to contaminate human food and cause food poisoning, and it also can affect puppies. Salmonella is found in the environment and some animals, or their feces. Puppies may become sick from eating contaminated raw foods, "varmints" or animal droppings, and sometimes even commercial pet foods become contaminated. It can make puppies very sick and cause diarrhea and vomiting. Learn about the signs of the disease, how it's treated and ways to protect your puppy in this article about salmonella.
Heartworms hide on the inside of your puppy, and are an insidious parasite transmitted by mosquitoes that can cause heart and lung damage and ultimately kill your pet. Thankfully, there are very effective preventive medications available. Learn all about heartworms in this article.