Steve Posted August 21, 2012 Share Posted August 21, 2012 This one is good too if you are considering breeding in future. http://www.showdogsupersite.com/kenlclub/breedvet/herx.html Link to comment Share on other sites More sharing options...
Steve Posted August 21, 2012 Share Posted August 21, 2012 And this one is good reading too. http://www.sotcdogtraining.com/pdf/heartworm.pdf Quote. Heartwormsmust go through several life stages before they become adults infesting the heart of thehost animal. Initially there must be an infected host animal wherein theadult heartworms bear live young, known as microfilariae. The microfilariae then circulate in the bloodstream of the host for as long as two years,waiting for the next stage in their life cycle in a bloodsucking mosquito. When ingested by a mosquito, themicrofilariae undergo a series of molts to the infective, or third, larval stage and then migrate tothe mouth parts of the mosquito, where they wait to infect another host by beingdeposited on the skin of such. These changes inside a mosquito can occur inas little as two weeks and as long as four weeks, depending on the warmth ofthe climate, and generally cease entirely at ambient temperatures below14° C. This time frame involves a simple formula of counting the degreesabove 14° reached each day. Each degree is called a heartwormdevelopment unit and when 234 heartworm development units have accumulated withina 30-day period, conditions have been reached that will allow thetransmission of L3 life stage heartworm to new hosts. If 30 days pass and 234 heartworm development units have not accumulated, mosquitoes will bedying from the cold before any microfilariae they carry can develop to theinfective stage. If a mosquito bites a dog before the larvae reaches stage 3,infection will not occur. Nor will a dogcatch heartworm from microfilariae in a blood transfusion or from nursing an infected mother as theinfective stage can only be achieved inside a mosquito. There are laboratory studies that indicate that developmentto the L3 stage requires the equivalent of a steady 24-hour dailytemperature in excess of 18C for approximately one month. Intermittent daily declines in Temperature below the developmental threshold of 14 C forshort periods (<2hrs) retard maturation, even when the average dailytemperature supports continued development. At a minimum daily temperature of 27C, 10 to 14 days are required for development of microfilariae to theinfective stage. After the third stage larvae are deposited on the skin of adog, they stay close to the mosquito bite entry site and grow very little duringthe next several days. The molt fromthird to fourth-stage larvae occurs 6-10 days after infection. Fourth-stage larvae migrate through subcutaneoustissue and muscle toward the upper abdomen and thoracic cavity.Fourth-stage larvae grow to about 1/10" in length during the next 40-60days and then molt to the fifth and final larval stage, or young adults. The youngadults penetrate veins to get into the blood stream and eventually, after 70-90days in the dog, reach the heart. Mosquito Life Cycle Also important herein is that the probability of any onemosquito bite transferring infectious heartworm can be quite small. First, as noted above, a mosquito must pick up heartwormmicrofilariae from a host animal. Thenthe microfilariae must undergo a series of molts within the mosquito to the infective, or third, larval stage, whichtakes around two to four weeks. Finally,a mosquito must deposit the infective stage larvae on the skin of another animal where they must survive another threeto ten days and molt from third to fourth-stage larvae to migrate throughsubcutaneous tissue and muscle toward the upper abdomen and thoraciccavity. An animal with a healthy immune system makes this migration very hazardousfor the larvae. Several studies have found that the number of microfilariae ingested by a mosquito is in direct proportion to the mortality of eithermosquito or microfilariae within the mosquito. The studies with Aedes and Culex mosquitoes also found that the number of L3 (infectivestage) larvae that reached the mosquito mouth parts was on average 1.5. A conclusion of the studies was that animals with low microfilariae density areimplicated as the main source for the transmission of D. immitis from dogs tomosquitoes. Considering that a dog with a healthy immune system furtherreduces the Considering that a dog with a healthy immune system furtherreduces the number of L3 to adult stage heartworms, it would seem that adog would have to be bitten many times by mosquitoes with infectivestage larvae for a serious number of adult stage heartworms to develop Let'sback up a minute and also consider that the female mosquito, when biting the initial infected host, consumes more than itsweight and will not feed again for three to four days. Let's also consider that most female mosquitoes can survive up to a month (or longer incaptivity) but most probably do not live longer than one to three weeks innature. Their chances of survival depend on temperature and humidity, not beingeaten themselves, and also their ability to successfully obtain a blood mealwhile avoiding host defenses. So, from the time the female mosquito bites the initialinfected host, around three weeks at a minimum must pass before infectious stagelarvae can be deposited on the skin of another animal. Thus most female mosquitoes will have only one opportunity to potentially infect anotheranimal, and then only if they have bitten an infected host early on and survive atleast three weeks afterwards in optimal conditions. If one is in a seasonal mosquito area, it should also beapparent that the threat of an infectious mosquito bite in almost the first month ofconducive temperatures is virtually nil (unless an infectious mosquitois shipped to your immediate local from the gulf coast :-). The idea that mosquitos might linger around inside say yourhouse might be a concern at the end of a mosquito season for a month or twoat the most, but after that they will be dead, and if they have managed topropagate, the new mosquitos will not achieve an infectious state unless thereis also a host animal present. Inseasonal mosquito areas there is no real justification for year around chemoprophylaxis other than profit, or to treata heartworm positive dog. In subtropical and tropical zones there are some longerlived mosquitos, and usually a greater host pool, so augment this informationwith local conditions. Someadult mosquitos can hibernate over coldmonths, and though there is evidence that viruses in such may not bekilled, I can find no evidence that heartworm microfilariae can survive such Link to comment Share on other sites More sharing options...
Dagmar Posted August 22, 2012 Share Posted August 22, 2012 I regularly worm my dogs with a natural product as worms tend to become more and more resistant to chemical wormers. I am using food grade Diatomaceous Earth and it works beautifully! Even the vet rang me one day and asked what I used. Here is more information about it: http://animalconnection.com.au/Natural_De-wormer.php Link to comment Share on other sites More sharing options...
milacon Posted August 22, 2012 Share Posted August 22, 2012 Yikes... I've just given my 13 week old pup his 2nd interceptor worming chew (for small dogs) which contains heartworm? Any harm done now? The vet didnt even mention that heartworm was inappropriate for puppies... Link to comment Share on other sites More sharing options...
Steve Posted August 22, 2012 Share Posted August 22, 2012 Vets go by what the drug companies tell them and some go by their profit margin. No matter what anyone including your vet tells you research it and take a good look at what the actual drug notifications tell you rather than the promo stuff put out by the drug companies. Also before you say go ahead research your risk factors, life cycles of the parasites you are supposedly trying to avoid etc to work out for yourself if its the best thing for your dog. You cant take back out what is already in but a good lesson learned when you only have a new pup. The reason I advise everyone to take out pet insurance for the first year is because vets bomb these babies with over vaccination , heart worm drugs when they are stressed already - going through changes in environment,foods and hormones etc .You often see a rash develop or other immune related issues a few weeks after a vax or heartworm meds etc and you don't associate the symptoms with what has been given because it isn't an instant reaction. After the first year booster many educated owners dont vaccinate anymore and dont give heart worm vaccinations so the immune systems arent challenged as much. By the way its the same when you are feeding only one type of commercial food. First reaction of the dog is that its coat gets shiny and poos are nice and firm and you think all is well but over time you may be over of underfeeding specific nutrients which will affect the dog's immune system etc but because its a slow show you dont associate it with the symptoms in a few months time. Challenge everything. Link to comment Share on other sites More sharing options...
Steve Posted August 22, 2012 Share Posted August 22, 2012 I regularly worm my dogs with a natural product as worms tend to become more and more resistant to chemical wormers. I am using food grade Diatomaceous Earth and it works beautifully! Even the vet rang me one day and asked what I used. Here is more information about it: http://animalconnect...l_De-wormer.php Yep. Link to comment Share on other sites More sharing options...
GeorgieB Posted August 22, 2012 Author Share Posted August 22, 2012 Thankyou for all that information Steve! Link to comment Share on other sites More sharing options...
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