A dog can pick up parasites anywhere. If yours spends a lot of time swimming or playing in freshwater streams or lake, he could pick up the intestinal parasites known as Diphyllobothrium latum. That's the formal name for freshwater fish tapeworms. Often, the presence of Diphyllobothrium latum cause no symptoms in healthy dogs, but they pose risks in older or debilitated canines.
Diphyllobothrium latum exist in freshwater rivers, lakes and streams throughout North America. In each stage of development, they live in different hosts or habitats. Diphyllobothrium latum don't have mouths. The tapeworms feed by absorbing food from the host's intestines. These hermaphroditic tapeworms fertilize themselves. Diphyllobothrium latum continue growing throughout their lives. Some of these yellowish-white worms can reach lengths beyond 39 feet.
Diphyllobothrium Latum Transmission
In order to acquire Diphyllobothrium latum, a dog must consume a freshwater fish carrying the parasites. However, that fish must have already eaten a small crustacean known as a copepod, another tapeworm host. In the dog, the tapeworms lodge in the small intestine. From there, they begin reproducing, passing eggs through the canine feces approximately six weeks after infection. Cats are also vulnerable to Diphyllobothrium latum infestation, but they can't acquire the parasites from dogs, and vice versa. Humans can also acquire these tapeworms through fish consumption.
While many dogs remain asymptomatic after ingesting Diphyllobothrium latum, others exhibit gastrointestinal problems. The tapeworms can deplete a dog's vitamin B12, or cobalamin, causing a deficiency if the dog doesn't receive sufficient amounts of the vitamin in his daily meals or through supplementation. Dogs deficient in vitamin B12 might experience diarrhea, vomiting and weight loss. If you suspect your dog has Diphyllobothrium latum, don't give him vitamin B12 supplements -- take him to the veterinarian for an examination.
Diagnosis and Treatment
Your veterinarian will request that you bring in a fecal sample so she can perform a fecal flotation to determine if worm eggs are present. It's possible you could see evidence of the worms if your dog throws up. If so, bring a sample to the vet. Your vet might prescribe praziquantel, marketed under the trade name Droncit and Drontal, to eradicate the worms. Praziquantel also gets rid of other types of tapeworms, but your vet might recommend a higher dose than normal to eliminate Diphyllobothrium latum. Other commoneworming medications -- such as ivermectin, which is in many heartworm preventives -- don't work for tapeworms.
Jane Meggitt has been a writer for more than 20 years. In addition to reporting for a major newspaper chain, she has been published in "Horse News," "Suburban Classic," "Hoof Beats," "Equine Journal" and other publications. She has a Bachelor of Arts in English from New York University and an Associate of Arts from the American Academy of Dramatics Arts, New York City.