Hookworms are pandemic in the US racing greyhound environment from farm to track and most racing kennels. Aggressive use of hookworm medications has resulted in the worms developing resistance to the more commonly used medications. Most greyhounds retiring from racing or displaced by the COVID-19 pandemic and Florida wagering ban closures will have an active hookworm infestation.
After the break I’ll describe what our local adoption agency is doing for new retirees, describe the treatment protocol, and the hookworm characteristics that led to the development of this protocol. The references include Greyhound Health Initiative papers (a bit scholarly), and and articles at Greyhound Friends and Ohio Greyhound Gathering and Adoption, two regional adoption charities. The Jennifer NG, DVM, article contributed to the OGGA website is a good lay introduction to contemporary hookworm management in greyhounds.
- 16 April 2020. Reorder to move the original paragraphs 2 and 3 below the break. Add application experience. Add reference 5. Relate kinematics to larval hideout.
- https://www.greyhoundhealthinitiative.org/resources/ Greyhound Health Initiative reference materials.
- https://www.wormsandgermsblog.com/ Companion and horse medical safety topics
James River Greyhounds new adopter recommendations
Per  six to eight months of treatment with Bayer Advantage Multi can be required to completely eliminate an infestation. Periodic surveillance by both fecal flotation and IDEXX fecal antigen testing is indicated and treatment with Advantage Multi should continue until several (at least three) months of clean samples have been observed.
James River Greyhounds is providing 3 months of worm prophylaxis using Sentinel Spectrum and Bayer Advantage Multi. The two medications are administered as directed on a monthly schedule with a 15 day stagger between the two products. The two products have different active medications. The thinking is that by alternating the two products establishes effective concentrations of each simultaneously and that the two materials together in staggered monthly application will be more effective than either alone.
Advantage Multi Topical Application
Advantage Multi is a thin topical solution applied to the withers. In Rocky, application was easy enough but absorption was slow and the material spread from the withers onto Rocky’s side. Per manufacturer’s literature, contact with the treated area should be avoided for 2 hours and critter should be kept dry while the material is being absorbed.
Spill from the withers does not affect the treatment as the moxidectin will be absorbed through the skin away from the withers. But spreading does enlarge the area to be avoided and may increase the amount of material exchanged with environmental objects or people. The liquid is somewhat oily and a bit smelly as it contains an odor additive to discourage licking.
Dormant Hookworm Larvae Hideout
Dormant hookworm larvae are able to hide out in your hound’s tissue. When the level of worm activity drops in the intestines, the dormant worms become active sustaining the infestation . To be effective, treatment must be continued until multiple monthly negative surveillance results have been obtained. A typical treatment period lasts six to eight months. Moxidectin alternated with a second modern medication is the preferred protocol for eradication of a hookworm infestation in greyhounds.
Advantage Multi Kinematics
The removal kinematics of Advantage Multi’s active ingredient, moxidectin, are such that it reaches an equilibrium level that is therapeutically effective after 3 months of monthly application. Once this level is reached, any dormant worm larvae that are hiding out in tissue will be killed upon becoming active. This ability of the parasite to hang out in a dormant state makes re-infestation possible after after episodic therapy is complete.
Establishing an equilibrium level of moxidectin is an important element of the therapy. When the level of active hookworms drop and larvae activate, the moxidectin level is adequate to kill the emergent larvae. Because release of the larvae is gradual, the moxidectin level must be maintained for several months of clean surveillance results.
Alternating Advantage Multi with a second product
This protocol interleaves two deworming products, Advantage Multi and a second product having a different hookworm control agent. Virginia Greyhounds recommends and supplies Sentinel Spectrum as the second agent. Administer one product on the first of the month and the second on the 15th of the month.
Re-infestation from the Environment
Hookworm larvae can persist in moderate and warm climate soils. Hookworm larvae can enter a hound lounging on contaminated ground or can be ingested by eating fecal matter from an infested animal or by licking feet following an outing.
Rocky is shedding hookworm larvae in stool around the yard. I’m trying to pick up daily to limit the buildup of hookworms in the environment. Hookworms migrate up to 4 feet from stool and can penetrate the skin through bare feet or during direct ground contact to do some yard or gardening task. Showering after gardening or mowing (soil dust) has become a mandatory health protection practice.
Missy, my incumbent, likes to lie out in the garden. It is possible that she’ll become infested also. Given Rocky’s hookworm status, what prevention protocol and surveillance protocol should I follow for my incumbent girl, Missy? I have a query into Greyhound Health Initiative and will update this post when I hear back from them.