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Mosquitoes and Dogs

by Tim Day

        It occurred to me the other day in class, that some of you might have some interest in learning about the lowly mosquito and how they can potentially affect your hound. What spurred this on is the fact that I start the year doing a fundamental chapter on how life is defined. As a part of this, I do a lab where we look at microorganisms in pond water. I decided a year or two ago that this would also be a great time to look at mosquito larvae and teach the kids some facts about them as well. Besides that, they do look pretty cool and they are pretty interesting! (Sorry guys, it’s the biologist in me!) So here goes, I’ll give you some information on their life cycle and how they affect your hound.

       First of all, you will find these little industrious creatures (larvae) in almost any little standing bit of water. It doesn’t have to be a vast expanse of water either, a little dip in a tarp covering, or a spare tire lying on its side, or an old cup, etc., etc. Basically they will be found anywhere water can stand. This summer in Indiana has been a very wet year, so finding the little adult bloodsuckers ahs been no problem! (I like the larvae, not the adult!) This might be a good juncture to inform you that it is only the adult for that is parasitic. The larval form is pretty much an herbivorous (plant) or detritus feeder, detritus is more of a dead type organic material. Now, I guess this is also a good time to tell you that only the female mosquito bites and withdraws blood! I relish informing my wife as to the female’s blood sucking abilities! Ha Ha! Course, you might be a bit wiser than I! Anyway, the female mosquito takes her blood meal in order to be able to lay her eggs. My guess is that there is a protein or other nutrient component that a mosquito doesn’t get from its normal food source. Which is what, you may be asking? Normally, they feed on the carbohydrate rich sap/juices of fruits or plants.

       One of the fascinating things about mosquitoes is the fact that they do go through a larval form. The fact that it has a larval form means that it goes through a process called metamorphosis. Meta- means change and morpho- is from body, so in other words a complete change in body form. Trust me, if you have seen the larval form you know that this is indeed the case! This larval form will be distinctly visible as it goes through its development. Eventually looking like sort of a ball with a tail that orients itself just right under the surface of the water. They do this through a tube that is literally attached to the posterior portion of their body, thus prompting one student to exclaim, “they breathe through their butt!”. Leave it to kids to well define a process, Ha Ha! Actually, by hanging upside down in the water they can see what is below, like minnows, etc., and are already positioned to propel themselves downward should danger come from above! It is however, funny to think of spending your youth hanging upside down!

      It is interesting to note that supposedly the only time in the life cycle that the mosquito grows is during its larval stage. As soon as it exits the water it is ready to begin its adult life. As we know, the desire of all living things is to reproduce, so it only stands to reason that mosquitoes want to breed. This is where the problem comes in for poor Rover. It seems that our little long nosed anti-coagulant carrying buddies can also carry heartworm larvae, which is another kind of a parasitic worm. Some more of those damned larvae again! Once inside poor Rover they can continue their metamorphosis process eventually culminating into a life in the heart (of your hound). They deliver these wonderful heartworm payloads when they (females) seek a blood meal. The heartworm larvae do not immediately go to the heart; they circulate for a while in the bloodstream. Therefore, if your hound is on a monthly preventative such as Ivermectin, then the larvae are killed in the bloodstream before they become a worm and attach to the inside of Rover’s heart. My understanding of Ivermectin is that it does not kill an established adult heartworm. Therefore, we will assume that the hound that has just been bitten does not already have heartworms.

       So your hound gets bitten, the evil mosquito that did it is carrying heartworm larvae. The heartworm larvae are called microfilariae. Pronounced micro – fill – a – ray. Once inside your hound they mature into adults within 2-3 months. In another 2-3 months they have achieved patency. This means nothing more than becoming evident. I assume that this means from a heartworm test perspective. Now, I used to think that heartworm were on a 6 month cycle and you could catch them anytime within this cycle. Not really true. At some point within this 6 months to adulthood, they will make their way to the heart. Once in the heart you are looking at some expense as well as danger. I have a buddy that had two hounds treated for heartworm this year. There was a better than average risk for the hounds and a pretty nice price tag. He wished he had been more diligent with his proactive defense.

        So what is the risk? Well, from what I gather much greater for hounds than for cats. This may be due to host specificity (they are more of a canine parasite) or who knows, they may have a better immune system! Regardless, I read where the percentage of infection for dogs is nearly 100% of those exposed! Man, that is high! So what is the consensus? Get your hounds on a preventative regiment! There are four compounds approved in the US and they are Ivermectin, Milbemycin, Moxidectin, and Selamectin. Your Vet can help you figure out what is best and what dosage you can administer.

      There is some good news if you have never treated your hounds in a preventative manner, and that is the fact there are several good tests available. They are very sensitive. One of the best is the antigen test. Let me give you the Tim Day definition: Ever wonder why you are so unique? Ever wonder why organ transplants are rejected? You have proteins and carbohydrate chains on the surface of your cells. Scientists often refer to some of these surface markers as antigens. You have some that no one else has, while at the same time having some that are uniquely human. So your tissue could be identified as uniquely yours while at the same time definitely human. Well, science developed such a surface marker test for heartworm, thus distinguishing compounds from heartworm in the blood of your hound. Neat, huh? Okay, so maybe I am to easily amazed!

        Lets close with a couple more facts about mosquitoes. First of all there are at least 2,600 different species, possibly more have been identified by now. The male is the weaker and smaller, and is basically a breeder. (Some of you may be thinking there are worse ways to go! Ha Ha) They have adapted to nearly every environment, and if I understand correctly are found as far north as the Artic Circle! They are resilient and cause more deaths and disease every year than cancer and heart disease combined! Millions of dollars are spent to fight the little beasts, but they carry on. Better get ole Rover on a heartworm preventative! Good running.

Should you have a concern regarding the health of your Beagle(s), you should contact your veterinarian. All information on this site is presented solely for educational and informational purposes and should not, at any time, be considered a substitute for seeking or receiving veterinary care for your Beagle(s).