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Canine Lungworms in Colorado

January 2014  

   For many years we have seen lungworms in our livestock species: cattle, goats, sheep, camelids and even horses.  We have diagnosed lungworms in all of these species in 2013.  Almost every animal from pet rats and hedgehogs to elk and zebras can all have lungworms diagnosed as a cause of coughing or pneumonia.  It has been a few years since our clinic has diagnosed lungworms in cats.  It should be noted that there are at least 8 different species of lungworms, and each species of animals can have a different kind of lungworm that will not affect other species.    

     Recently we have seen 4 cases of lungworms in dogs in 2013.  This is unusual.  Historically these lungworms are very rare in our area.  Three of the four dogs were imported into our state for adoption.  We are aware of many diseases which can occur in animals that have visited back east or down south.  This is a reason why we ask about travel history during a veterinary examination.  Finding one of the tick diseases (Lyme, Ehrlichia and Anaplasmosis) or even heartworms and some lungworms should not be alarming if the dogs are from down south, back east or even New Mexico (Ehrlichia).  The unusual thing in one of the dogs was that the lungworms were resistant to the typical treatments utilized.  Overall a parasite resistance to dewormers is fairly rare, and yet it does occur.  As FYI this past summer we had two flocks of sheep with Haemonchus parasites that were resistant to 3 different dewormers.     

     “Tex” was a 6 year old Golden Retriever that was adopted locally in 2011.  Originally he came from Mississippi.  A routine stool fecal early in 2011 was negative for parasites.  In late 2011 a second fecal was performed because he had a cough.  The routine fecal was negative and the cough responded to a treatment for kennel cough and Mycoplasma.   In the summer of 2013 the cough returned and the history was that Tex still had coughed a few times a month, but it did not seem to be a problem until recently when it worsened.  A routine CBC, mini-panel, heartworm exam and lung radiographs were normal.  We then performed a lungworm fecal exam, which is a separate and different test than the routine spin-down fecal test.  After the test was positive the owners preferred to treat the dog with 1.5x the dose of ivermectin.  He was treated 5 times.  A recheck fecal showed that this treatment did not work, so a treatment of fenbendazole was started.  After a week of fenbendazole the treatment was accidently stopped, so a second round of 15 days of therapy at the double dose/high dose was given.  With some mild coughing the 3rd lungworm exam was again positive.  Utilizing a different avermectin product Tex was successfully treated.  A routine fecal exam will not diagnose lungworms.

     Depending upon the species, lungworms require two species of animals to complete their life cycle, such as a snail, slug, crawfish, amphibian, reptile or bird (cat lungworms).  There is also a dog/fox lungworm species which has a direct life cycle and needs no intermediate host.  You should not be concerned about dog lungworms in our area, nor should you even consider using snail and slug poison products as these baits area very toxic to pets.  A lungworm fecal exam is not indicated for the average pet unless they have a coughing problem that does not respond to the first round of treatment for the more common respiratory type of pneumonias that we see.

     A periodic fecal exam will help diagnose most of the internal parasites that we see in all animals.  We have a strategic deworming program for livestock and horses that includes a periodic fecal exam.  We periodically perform post deworming fecal exams as part of the strategic deworming program, in order to find and diagnose resistance to a dewormer before there is a crisis.  All coughing animals should have this inexpensive lungworm fecal test performed if the initial treatment did not cure the problem.