Even cats from the finest homes may eat a mouse now and then, given the opportunity. Cats have been eating mice for thousands of years. That made them valuable to the ancient Egyptians when they began cultivating and storing grain. Cats earned their keep and a chance at domestication by killing and eating mice.
It should come as no surprise then that mice are good cat food. Mice are even low in a trace mineral - magnesium - that can help prevent urinary problems in cats. But sometimes, especially in today’s world, mice can come with baggage that is harmful, or even fatal to cats.
Modern farmers use rodenticides - rodent killers - to get rid of mice. The poison typically works by inhibiting blood clotting. Even if you don’t cut yourself, you could not live long without normal blood clotting, and neither can a mouse. Before long a little leak would start somewhere, perhaps in the chest or abdomen. Other animals, like dogs and cats, commonly eat rodenticides too, and may die suddenly, with no apparent bleeding, several days after eating the poison mouse bait. An autopsy may show the dog or cat bled to death internally. As mice developed a tolerance to rodenticides, new poisons were developed and are so toxic that a cat can die from eating a mouse that had eaten mouse poison.
Prompt emesis - making the cat puke - can prevent poisoning or reduce its severity. A couple of simple blood tests can tell if an animal has impaired blood clotting or is bleeding internally. A blood transfusion may be needed. Even if the cat vomits everything out of its stomach and the blood clotting tests are normal, an injection of a particular type of vitamin K, is often recommended, followed by pills for up to a month or more, to be safe.
Cats get infected with tapeworms by eating mice that are carrying the tapeworm larvae. Inside the cat the larvae mature and grow into a tapeworm. Pieces of the tapeworm are shed when the cat has a bowel movement and each tapeworm segment contains thousands of eggs. Other mice get infected by eating grain or something contaminated with tapeworm eggs.
Many parasites have complicated life cycles. There are many other species of tapeworms and almost all of them involve a primary host, like the cat (or dogs, people, and horses,) and an intermediate host, like the mouse (or fleas, cattle, or insects.) Fleas are the most common intermediate hosts for tapeworms in dogs and cats. Rodents can also infect cats with other parasites, like lungworms and roundworms.
Cooking kills or inactivates many of parasite larvae. If you could train your cat to bring his mice to you so you could cook them, or at least zap them in the microwave, it would reduce the chances of infection with these parasites. But I doubt if cooking would help inactivate rodenticides.
Eating mice can also be a cause of the barfing and the “green apple quick-step” that is so pleasant to find with your bare feet in the early morning. I would recommend that you encourage your cat to limit his diet to a good quality cat food. If he insists on a more natural diet, at least watch the cat closely for unexplained bruises, labored breathing and lethargy, and watch the yard and household for pieces of rodenticide packaging. Rodenticides are also usually colored - green or some other distinctive color - so watch for that in what he is eating, or what he pukes up. P>Return to Dr. Roen's Weekly Column