What we thought was D-con poisoning turned out to be Whipworms
(Creston, Iowa, US)
My 4 yr. old Bassador, who has a very lazy demeanor anyway, was getting very lethargic. (more than normal). We had just caught a nuisance rat with D-con and knew that we had not placed the poison anywhere that our dog could come in contact with it and ingest it. I then thought maybe the rat carried the D-con in its mouth and dropped it where our dog could eat it or the dog could've snagged the rat (when poisoned) in its mouth.
Every time our dog attempted to walk up or down even the littlest step , I'm talking like an inch, she would face plant herself. She was trembling, incoherent, and panting a lot. She never lost her appetite and her stool was very normal. She began losing weight for no apparent reason. There was no vomiting or diarrhea. You could literally see her ribs along with a few other bones. We took her to the vet about a week after very noticeable symptoms fearing the worst and ready to euthanize her. It turned out to be whip worm, which I've never heard of. She was prescribed Panacur granules along with a dose of Advantage multi. which I was told would kill any other kind of parasitic worm she may have. Also, she was tested for heartworms which was negative. My other dog will be tested next but does not or never has shared the same sleeping area or dog house. Is there any easy way to remove the whipworm from my soil?
It sounds like your dog showed the less common secondary symptoms that imitate Addison's Disease, mainly weakness that inexplicably comes and goes.
In answer to your question, unfortunately, whipworms can live in the soil for several years and I have never read through research, nor found a veterinarian who has a remedy for getting rid of these parasites in the soil.
The best way to prevent recurrence is to make sure your dog is the absolute healthiest he can be. This means feeding your dog a high-quality food such as Innova, Blue Buffalo or Wellness, to name a few.
Normally, after a dog has been rid of intestinal parasites, a heartworm preventive, such as the one you are using, will keep the worm from returning or at least under control. Be sure and read our "Heartworm" page for guidance on administering heartworm meds.
Good luck to you and your fur kid!