Ivermectin for dogs: history, indications, side effects, and related causes of infestations

In 1974, a routine screening test of naturally occurring soil organisms took place at a golf course in Japan. An organism known today as Streptomyces avermectinius was discovered and it has an active compound called avermectin that was identified in 1975. From that active compound, ivermectin was synthesized. Later on, researches have proven its potential to treat and prevent common intestinal worms, mites and some lice by blocking muscle activity on these parasites dwelling within an animal’s body and eventually causing them to be paralyzed and be killed later. Its broad spectrum of activity has allowed the United States Food and Drug Administration its use in the veterinary field since 1981, as well as its recommended dosage that was found out to be 50 times lesser than most anti-parasitic agents in that decade. Today, Ivermectin is available in many brands and marketed by various animal health care companies in formulations of tablets, chewable tablets for heartworm prevention, topical solution for ear mite treatment, and oral or injectable solution for other parasite diseases.


Ivermectin has been approved to treat or avoid parasitic and intestinal problems outlined below:

  1. Heartworms. Veterinarians recommend monthly prevention of heartworms in dogs. Along with heartworms, hookworms and roundworms are also common. Heartworms are carried by mosquitoes, and a bite from a mosquito infected with these parasites will cause transmission of the disease to your dog. All dogs are prone to these parasites. Therefore, it is a must that you have a regular schedule with your veterinarian to ensure that your dog is safe from heartworms. Symptoms of this disease is not easily detected, and even when diagnosed it is usually too late for treatment. Heartworms will directly damage the heart of your dog making them very lethal. As a standard procedure veterinarians conduct annual heartworm test before prescribing monthly heartworm medicines to protect a dog’s health.
  2. Ear mites. Topical preparations of Ivermectin are available for use only on ear mite infection since there is a zero probability for any dogs to bite or lick their ears infested with mites as a result of the itchy feeling. The use of topical solutions is not recommended on other parts of the body because direct contact with the drug by tongue may poison the dog. Remember that Ivermectin is technically a poison, although it is generally a safe drug, because they kill parasites and worms.
  3. Demodectic mange. Mange is a group of persistent contagious skin diseases. When we say demodectic mange, it is a skin disease caused by the parasite demodex. Sensitivity to and overpopulation of demodex will weaken the immune system of a dog and even its natural defenses against parasites will disable it to control the mites. It could be a localized demodicosis, where there are small circular areas in the dogs body that show hair loss or baldness. Generalized demodicosis is more widespread and cause lesions and blood discharges caused by frequent scratching or biting.
  4. Sarcoptic mange. It is also a parasitic disease that causes extreme itchiness and hair loss which eventually leads to skin rash as a result of a mite known as Sarcopsis scabiei. In simpler terms, it is known as scabies. The lesions in the dog’s body associated with this particular skin disease are itchiness, skin rash with reddened and inflamed skin, scabs on the skin, and hair loss.


Ivermectin is generally a safe drug. Side effects are not so much a concern. However certain precautions are exercised in some dogs that are sensitive to the compound. For one, Collies cannot be treated with the drug as well as other herding breeds unless there is a close and strict supervision of a veterinarian. Other breeds that have high risks of ivermectin toxicity include Shetland sheepdogs, Australian shepherds, and Old English sheepdogs. The reason for this is that these breeds are affected by a genetic defect that makes them sensitive to antibiotics, opioids, and steroids and over 100 more drugs. These dogs have a mutant gene known as “P-glycoprotein” which has the ability to keep drugs from entering body tissues but does not have the ability to keep them away from the central nervous system (CNS). Insisting the use of ivermectin on these breeds will manifest certain CNS side effects that may cause serious harm or damage to the dog’s brain.


The most trusted way to ensure that dogs are provided with the correct therapeutic doses is to consult with a veterinarian. Although we may be tempted to buy anything on the Internet offered at very low prices without the need to present prescriptions, a dog’s health and life is best evaluated by an experienced professional. They were well trained to diagnose a dog’s present condition, to assess the accompanying early and progressive symptoms of a particular illness, and to decide on which medication to recommend with the accompanying dosage fitting for the dog’s disease and body weight. Incorrect use of the compound whether they are in small or large doses may cause serious side effects and have been proven to be fatal to your dog.

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