As a vet tech.. and TONS of experience in parasitology
I find the subject fascinating.. BTW..
False negatives in a fecal is common.. For all worms, Coccidia, and yes even giardia.. There are LIMITS to what parasites you are going to see on different methods of Fecals.. Parasites don't shed ova, eggs all the time too.. all equals often multiple samples run to ID.. so yes it happens.. in dogs, cats as they are far more resilient and there is more research and safety info.. often they are just wormed.. Have a dog use a monthly Heartworm med? almost all also contain a additional wormer to cover GI parasites.. just in case (some dog/Cat) parasites can infect people so there is a health risk.. its only in our domestic dogs, cats and us humans where anything other than a negative no parasites ever is the norm.. most other animals finding specific types is yeh.. normal don't treat unless there is symptoms of disease going on or extreme stress where the parasite can overtake the immune system..
Direct smear actually is better for things like giardia or protozoan parasites as they are VERY tiny.. so finding them is looking for movement, then focusing down on them.. Giardia specifically is darn hard to pick up on in house style fecal float..
I don't see it in your pictures, but having run THOUSANDS of fecals 99% of the time I have caught giardia by seeing the tell tail circular, squiggly movement then focused down, or done a smear and even a stain on a direct smear and ID giardia.. on a stained smear I had to use oil immersion to see it clearly..
If he is being treated for giardia.. the meds paralyze the parasite.. so may not see it right now.
Coccidia.. It looks the same in all species heck so does the Pinworm.. and Giardia.. neat right?? I can run a fecal on any animal and see and note parasites, just may need to look up and ID them.. Pinworms in dogs is very rare, so that "shape" egg is unfamiliar.. but Giardia, Coccidia, Roundworm, Liver fluke, Lung worms.. All fit into the same "shape" think of how you can recognize a cat, or dog, or heck a chameleon.. Just not know what specific species it is?? same with those pesky little parasites..
so there really should not be any confusion between giardia and coccidia, also Giardia IS much smaller.. So I doubt they confused it..
Coccidia is a stress parasite.. often shows up at times of stress.. Why you can have say even a dog, go to the vet have a exam Neg fecal, go to a new home a day or two later, and diarrhea.. opps now has coccidia.. It was there all the time, and will ALWAYS be there one never gets rid of coccidia, however at times of stress they shed it, and treatment is to knock down the parasite enough for the immune system to keep it in check.. at least in dogs unless you are seeing TONS, have other symptoms.. often a positive coccidia result does not equal treatment..
I would ask however, to see the lab results.. see if it was noted.. that is something the vet should have said and why.. and express that you would like copies of the results and be given all the info and why.. If it was run in house ask did they see pinworms and coccidia? and if yes.. ask why no treatment.. sometimes vets forget.. what is standard knowledge, not a significant finding a owner may not know, or heck want to know anyhow.. in many species some parasites are common.. and what is considered a Not significant finding, don't treat unless specific medical reason...
Just curious however, what is he being treated with? it is possible it is broad spectrum enough to cover other stuff "just in case" in addition to the giardia..
Now I Don't specifically know what meds they use in a Cham.. However some wormers get several types of worms, and can treat Giardia - panacure (fenbendazole) is one.. Coccidia at least in Dogs/cats Birds etc.. you use a antibiotic in the sulfer class.. So possible may be treating for all or many just by drug selection...
