Mange is caused by microscopic mites. Demodectic mange is either localized, with fewer than five isolated lesions, or generalized, with five or more lesions covering a region or the entire body of the dog. Dogs with sarcoptic mange have red, scaly skin and are extremely itchy as female mites burrow under their skins. Dog owners' home treatment of choice is ivermectin, but this extremely toxic medication carries risks. Owners must consult their veterinarians before using it.
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Ivermectin Mange Treatment
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Ivermectin is a broad-spectrum anti-parasitic dog medication used against lice, intestinal worms and heartworms. It successfully kills mange mites, but it's not approved for this purpose by the U.S. Food and Drug Administration, or FDA. Ivermectin is administered orally or via injection daily or every second day.
High doses eradicate mange quickly. However, "This does not mean that a pet owner should experiment with ivermectin doses on their own, as there is some potential for lethal toxicity if this drug is not used appropriately," warns the Mar Vista Animal Medical Center in Los Angeles.
Ivermectin is sold under various brand names including Ivomec, Heartgard, Iverhart Plus, Tri-Heart, Acarexx, Stromectol, Mectizan and Ivexterm.
Fatal For Some Dogs
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Ivermectin can be fatal to dogs of any breed or crossbreed. However, sensitivity is most common in herding breeds. The highest sensitivity rates are in collies, Shetland sheepdogs, Australian shepherds, Old English sheepdogs, long-haired whippets, McNabs, Silken windhounds, border collies, English shepherds and German shepherds, according to the website for the Washington State University College of Veterinary Medicine.
Drug sensitivity results from a mutation in the multidrug resistance gene MDR1. Mutant MDR1 genes can't pump some drugs out of dogs' brains, resulting in neurologic problems and sometimes, death.
Pre-Use Testing
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It's prudent to try low test doses of ivermectin on dogs before administering the high doses required for mange treatment, according to the Mar Vista Animal Medical Center. Ideally, owners can test their dogs for ivermectin sensitivity and the mutant MDR1 gene by ordering and submitting a test kit to Washington State University's College of Veterinary Medicine. No special training is required to collect the cheek-swab DNA samples.
Veterinary clinics can also submit dogs' DNA samples--2 cc of blood--to Washington State. Test results generally are available within two weeks.
Incompatible Drugs
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Ivermectin should not be used with Valium or related tranquilizers. It shouldn't be used with Mitiban or Amitraz mange dips, or with Amitraz (Preventic) or other tick collars. These medications are members of the monoamine oxidase inhibitor group. Their efforts accumulate, according to Mar Vista Animal Medical Center, creating sedation and adverse neurologic effects.
Ivermectin is also not compatible with the commonly used flea product spinosad, marketed as Comfortis.
Expert Insight
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The Mar Vista Animal Medical Center advises, "While we recognize that it is possible to buy large-animal formulations of ivermectin (such as Ivomec) through catalogs, we strongly discourage this practice because of the potential to easily give a toxic dose. ...Large-animal formulations are much more concentrated, and it is extremely difficult to measure a dose appropriately for a small animal." Owners are safest contacting their veterinarians before measuring and administering ivermectin to their dogs.
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