Expert: Jessica - 5/12/2011

Question
I read your response to a previous question about cats with bots and would like additional clarification, if you don't mind.
I have three cats who seem quite healthy, but lately I have noticed tiny little black bugs in their dry cereal. I leave three dishes of cereal out inside the house for them to nibble whenever they need a snack.  I'm pretty sure that these little black critters must be ingested by the cats and they eat, but I'm not 100% sure. An article I read on another site says that they are not fatal to cats, but it seems you feel otherwise.
I also have Guinea Pigs...I had four, but lost two who were quite young. I have noticed these nasty little bugs inside the cages when I clean them.  I learned from a vet that Ivermectin, in very small doses will take care of the bots in the Guinea Pigs and have been using it for about a year.
I have never noticed any wounds on my cats and they play outdoors all day while the sun is up. The yard is fairly rural with lots of wild plants, sand and rock.
My concern is that the other article I read said that they are ingested and passed through the cats with little to no harm. Do you think I should be giving the cats the Ivermectin?  Also, do you think that I should NOT leave the dry food out for them all day?
My cats are four years old and were rescued at birth from a feral mom who abandoned them.  I bottle fed them and they managed to survive.  I am pretty much the only parent they have ever known...and I would be devastated if I were to lose any of them.
Thanks in advance for your reply, David

Answer
Hi David,

I can't be sure that it's bots in your cats' food. It doesn't sound like that's what they are to me, personally, but if you have identified them positively, then I'll base my answer on that.

Bot fly larvae are not generally fatal to cats. The only exception is if the larvae die while still living as parasites under the skin of the cat, OR if they leave an infection in the wound after exiting the skin. Some cats have a fatal reaction to the decaying larva (not all cats will, but this is a big chance to take). Also, infections of the bot site or relatively uncommon, but if it does occur, bacteria can enter the bloodstream. This condition, called septicemia, can be quickly fatal.

As far as ingesting the worms, what you have read is correct. Cats have a short and highly acidic digestive tract. This means that what they eat is digested and expelled quickly, giving it little chance to make the cat ill at all, and these larvae are not toxic anyway.

Ivermectin, on the other hand, is very toxic to cats. It should be avoided for use in cats except in the most specific circumstances. For instance, it might be used in the ears to treat ear mites, in a very diluted concentration under the supervision of a vet. However, it should never be given orally, and it should never be applied topically to an area where the cat can lick it.

Dry food is fine to leave out all day, as long as it has not been moistened at all. If you do moisten it, it should be discarded within 2 hours.

Best wishes!

Jessica