Fascinating

The last couple of weeks I have been in cardiology and this week in the Antec lab and parisitology lab of the teaching hospital.  Yesterday we echoed a dog that had a positive antigen test for heart worm adults.  The ultrasound image showed the worms in the right atrium and the right ventricle and one in between the two, through the tricuspid valve.  The dog was small (chihuahua) therefore the worms were large about as long as a #2 pencil and about as thick as a piece of horse hair.  For a small dog the worms were a big problem.  Seeing the worms on ultrasound one day then spending the next day in the parasitology lab performing a modified knotts procedure on ten patient specimens helped sink in the information.  A knotts procedure is taking 1ml of patient blood with 9ml of 2% formalin and centrifuging the sample.  Then pouring off the supernatant (top fluid portion), then taking 1 drop of new methylene blue dye and stirring it with the sediment (button) on the bottom of the test tube.  Taking the mixture and placing it on a slide with a coverslip then viewing it under a microscope is the next step.  The modified knotts' purpose is to differentiate two parasites (microfilaria) that circulate in the blood.  The most common one that is pathogenic is heart worm or Dirofilaria immitus.  The second that can be confused with dirofilaria is Acanthocheilonema (Dipetolenema) reconditum, it is not pathogenic.  Performing the procedure, we actually saw a dirofilaria microfilaria in the blood of a dog that had a negative antigen test.  Two reasons why this could happen the test was faulty or the young dog acquired the microfilaria from its mother through the umbilical.  Microfilaria can live up to two years in the blood.  The only way that the animal can be infested with the adults is if a mosquitoe ingests blood and grows into the next stage which takes two weeks and then drinks blood from another animal and passes the microfilaria to another animal which then those microfilaria grow to the next life cycle and become adults that migrate to the heart.  Google image heartworm and you will see that these worms are pretty nasty.  Now imagine those in your pet dog.  This can all be prevented by giving your dog heartworm preventative.  I will now step down from my soapbox.