After three clean stool samples in a row, our vet discontinued Drontal+ medication back in the spring. The 3 month check came back hook worm positive. So we’re back to square one with a new baseline fecal egg count and resumption of Advantage Multi plus Drontal+ parasite treatment. And did I mention, fecal egg count stool sample every 2 weeks.
Medication resistant hookworms remains an area of active investigation regarding treatment protocols. The University of George paper was published in August of 2020. The American Animal Hospital Association, AAHA, is updating treatment guidance about yearly. Several papers date to 2017 or so but did not initially influence practice as a change in practice was not indicated at the time. But difficulty in treating the initial infection and completely mopping up the infection are changing clinical practice.
Bayer Animal Health sold
Elanco now owns the Bayer Animal Health business and products. Lay product information is now at https://www.petbasics.com/
Management has not made any “optimizations”, always a concern following an acquisition as important patent products may be discontinued.
A new medication
Reference three suggests an additional drug, emodepside, the primary wormer in cats, as a medication to try in place of Drontal+ if the hooks keep returning. The Pub Med article  establishes safety and effectiveness of emodepside in canines.
A new test
Rocky tested clean by fecal egg count for three months before we discontinued the Drontal+. About six months later, he is again hookworm positive. This is not an isolated occurrence as hideout in the small intestine provides an internal source for reinfection.
IDEXX  has a fecal antigen test for hook worms that is more sensitive than the fecal egg count test. This test will discover active infections in the pre-patent phase about 30 days before the onset of positive fecal samples . Typical cost is $50, comparable in cost to the fecal egg count test. This test correlates well with the fecal egg count test during the patent period.
Reference  compares fecal egg count and ELISA tests in laboratory animals and in client owned animal infections. The article also talks about use of the test for initial surveillance, treatment effectiveness surveillance, and post-treatment surveillance.