Off label use for many first line treatments in cats and dog is VERY common. I sent this already in a PM to AddieBee, however wanted to post it here in case others run into the same issues
Updated information 2009 From the Companion Animal Paracite councilhttp://www.capcvet.org/recommendations/giardia.html
- No drugs are approved for treatment of giardiasis in dogs and cats in the United States.
- Metronidazole is the most commonly used extra-label therapy; however, efficacies as low as 50% to 60% are reported. Safety concerns also limit the use of metronidazole in dogs and cats."
The above article does go on to talk about using Fenbendazole as the drug of choice in cats.
article from 2000 http://www.critterchat.net/giardia_fands.htm
"There are several treatments for giardiasis; some of them have not been registered to treat giardiasis in dogs or cats. Metronidazole is one of these, but is the old standby. The nice thing about this drug is that it also kills some types of bacteria that could cause diarrhea. So if the diarrhea was caused by bacteria, and not Giardia, we still kill the cause of the diarrhea and eliminate the symptoms. Makes us look pretty sharp! Unfortunately, metronidazole has some drawbacks. It has been found to be only 60-70% effective in eliminating Giardia from infected dogs. In some cats and dogs it can cause vomiting, anorexia and some neurological signs. It also can be toxic to the liver in some animals. It is suspected of being a teratogen so it should not be used in pregnant animals. Finally, it has a very bitter taste and many animals resent taking it â€“ especially cats."
From the Wisconsin Veterinary medicine school tutorialhttp://www.vetmed.wisc.edu/pbs/zoono...l/giardia.html
"Fenbendazole (e.g., PanacurÂ® or Drontal-PlusÂ®) now appears to be the drug of choice.
Used in dogs and cats at 50 mg/kg for 3 (-5) days, fenbendazole has been shown to be completely effective in eliminating experimental Giardia infections, and with only mild vomiting/diarrhea as potential side effects."
From " The handbook of small animal gastroenterology" by Todd R Tams. editions 2 2003 chapter 7, page 215 http://books.google.com/books?id=2rR...esult&resnum=1
"Fenbendazole is now the preferred treatment for Giardia in cats. (Drontal Plus is approved for use only in dogs"