In “History and diagnosis of multi-anthelmintic drug resistant hookworms,” I discussed the history of multi-anthelmintic drug resistant (MADR) hookworms and how to differentiate between true resistance and other complications such as reinfection, treatment noncompliance, and suboptimal anthelmintic treatment.

Cassan N. Pulaski, DVM, MPH, PhD, clinical assistant professor and director of the Diagnostic Parasitology Lab at the University of Georgia College of Veterinary Medicine and a small animal relief veterinarian, has valuable insights on how to diagnose cases of MADR in dogs and here, she shares her thoughts on extra-label treatment option for MADR that can be considered when hookworms are not responding to combinations of commonly used anthelmintics.

Get to know emodepside

An article in Clinician's Brief by Pablo David Jimenez Castro, DVM, and Ray M. Kaplan, DVM, PhD, DEVPC, DACVM (Parasitology), describes describes the extra-label use of Profender, a topical parasiticide for cats, which has emodepside as its active ingredient. While it is labeled for topical use in cats, emodepside must be used orally to kill drug-resistant hookworms in dogs. The dose that has been suggested is 1 mg/kg.

Jimenez Castro and Kaplan clarify that they do not recommend this course of treatment due to limited safety data. Nonetheless, Pulaski reports that it is sometimes the only drug that works.

Important safety concerns of emodepside

There are multiple safety concerns with the extra-label use of emodepside in dogs.

Pulaski reports that the drug is very effective at killing heartworms. It kills them so quickly that a heartworm–positive dog that takes this drug orally would be at increased risk for anaphylaxis secondary to rapid, widespread worm kill off.

Additionally, Jimenez Castro and Kaplan report that dogs with the MDR1 gene for multidrug sensitivity may be at higher risk for “severe adverse effects,” especially if they are dosed incorrectly.  

Before deciding to use it to treat suspected MADR hookworms, Pulaski recommends running a fecal PCR test to look for look for the mutation that codes for benzimidazole resistance.

Jimenez and Castro also recommend treating patients with triple-drug combination therapy:

• febantel/pyrantel pamoate/praziquantel and moxidectin; or
• fenbenazole, pyrantel pamoate, and moxidectin.

They also suggest documenting failure of this treatment via FECRT first.

Best practices for emodepside use

When considering extra-label emodepside use, it is also important to choose patients carefully, screening for heartworm disease and the MDR1 mutation if appropriate.

Pet owners must be adequately warned about the risks and the extra-label nature of the treatment, and treatment must be administered in the hospital where patients can be monitored closely, according to Pulaski.

If emodepside treatment is elected, some dogs may need up to three doses of the drug to be totally cleared of their hookworms, but should not continue with this treatment long term.

Even if they reach “no parasite” status with emodepside, Pulaski cautions, these dogs should still have their fecal samples checked at least three to four times per year.

Their owners should continue to take precautionary measures to avoid reinfection and environmental contamination, including picking up feces immediately. She says some dog owners will place a paper plate on the ground before their dog defecates so that their stool never touches the grass.

Treatment strategies for MADR hookworms

Clinicians who are treating cases of MADR hookworms don’t have to struggle alone. Pulaski recommends some strategies that can support both pet owners and the veterinary team:

1. For dogs who have been receiving regular anthelmintic treatment and have suspected hookworm resistance, reach out to the manufacturer of the drug(s) they have been taking. The manufacturer will want to have this information, and they may be willing to assist with the cost of future treatment.
2. Veterinarians can also reach out to their local university parasitologist for assistance and guidance. Reference laboratories can be another source of expert advice.
3. Pulaski also recommends the “Getting rid of Parasites in Retired Racing Greyhounds” Facebook group. This group is moderated by a veterinarian and has a lot of good information.

Further reading

History and diagnosis of multi-anthelmintic drug resistant hookworms (NEWStat)
https://www.aaha.org/publications/newstat/articles/2024-4/history-and-diagnosis-of-multi-anthelmintic-drug-resistant-hookworms/

Persistent or Suspected Resistant Hookworm Infections (Clinician’s Brief)
https://www.cliniciansbrief.com/article/persistent-or-suspected-resistant-hookworm-infections

Reflecting on the past and fast forwarding to present day anthelmintic resistant Ancylostoma caninum–A critical issue we neglected to forecast
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10229760/

Emergence of canine hookworm treatment resistance: Novel detection of Ancylostoma caninum anthelmintic resistance markers by fecal PCR in 11 dogs from Canada (AVMA)
https://avmajournals.avma.org/view/journals/ajvr/84/9/ajvr.23.05.0116.xml#:~:text=the%20primary%20veterinarian.-,RESULTS,BZ%20F167Y%20resistance%20marker%20detection

Emily Singler, VMD, is AAHA’s Veterinary Content Specialist.

Cover photo credit: © Macrovector E+ via Getty Images Plus

Disclaimer: The views expressed, and topics discussed, in any NEWStat column or article are intended to inform, educate, or entertain, and do not represent an official position by the American Animal Hospital Association (AAHA) or its Board of Directors.