Fish may not be a regular treat on Rover's menu, but you may have heard about the benefits derived from feeding small amounts of fish every now and then. Fish is rich in protein and is often the main ingredient in low-allergen diets for dogs. Fish oil is great for Rover's coat. Beyond having fins and scales, however, not all fish are good for dogs. Some species harbor dangerous parasites. Some are poisonous or contain potentially harmful bones. Even the best fish pose a variety of hazards to consider.
Fish Carrying Parasites
If Fido consumes raw salmon or any of several other West Coast fish species, he could fall victim to salmon poisoning, a potentially fatal disease caused by a rickettsial organism called "Neorickettsia helminthoeca." This parasite infects salmon, sculpin, amprey, redside, shiner, shad, candlefish, sturgeon and the large-scale sucker along the Pacific coasts of Oregon, Washington, Canada and northern California. Thoroughly cooking the fish kills the parasite.
Fish with Mercury
Nearly all types of fish and shellfish these days contain traces of mercury. Large fish often contain higher levels of the metal, because they have lived longer, prey on other mercury-carrying fish, and accumulate mercury throughout their life spans. Swordfish, shark, king mackerel and tilefish are fish particularly known for posing the greatest risk, according to the Food and Drug Administration. For this reason, just as with humans, you should limit the amount of such fishes your dog consumes.
Fish with Chemicals
If you're considering feeding your dog locally caught fish, it's a good idea to ask your local health department about health advisories concerning consumption of various local fish species. Your local waters may contain higher-than-average levels of mercury or other contaminants such as dioxin, selenium and polychlorinated biphenyls (PCBs). As with ocean fish, many such toxins tend to accumulate in the fish over time, so larger, older specimens tend to carry higher levels of the chemicals. Fish that are higher in fat, such as catfish and carp, may store higher levels of polychlorinated biphenyls and other chemicals in their body fat.
Watch out for blowfish, a fish that can be found washed up on the beach or a river bank along the Florida and Gulf coastlines. Often, these fellows are discarded by fishermen. The fish produce a very powerful toxin known as tetrodotoxin, which can be fatal to dogs. If you suspect your dog has ingested this type of fish, contact your vet immediately.
Pay attention to where the fish you give your dog comes from. More than 80 percent of fish sold in the United States is imported, according to the FDA, and some of the countries they're imported from may raise fish using antibiotics and antifungal drugs banned in the U.S. The U.S. government lacks the resources to inspect more than a small sampling of the fish imported to the U.S., so it's important to be aware of possible issues.
General Fish Dangers
Be careful about feeding your pal fish that contains bones. Just as with other types of bones, fish bones can lodge in Fido's throat or irritate his gastrointestinal tract. Also, consider that any raw fish in general has the potential for harboring dangerous bacteria, such as salmonella. Salmonella not only poses a risk for Rover, but also for other family members and pets, according to the Cummings School of Veterinary Medicine at Tufts University. The best way to prevent the problem is by thoroughly cooking the fish.