Danger: Collie, Border Collie, Shetheland Shepherd and Ivermectin

Danger: Collie, Border Collie, Shetheland Shepherd and Ivermectin 


Last week serve two dogs of the breed Collie who live in the same house and were treated by the owner, WITHOUT PRESCRIPTION with 2 tablets of ivermectin for each of them.

After three hours began to show change in behavior, involuntary muscle tremors and incoordination. They were treated at emergency, induced vomiting (as was recently the intake) and after 48 hours were already high.

They were lucky because we were able to meet in time to induce vomiting and remove the product from the stomach, but not always the case and this case could be weeks hospitalized with complications from poisoning.

Ivermectin is a drug antiparasitic used for years in veterinary medicine in large animals (horses and cows). Nowadays it is very well used in humans (to treat scabies) and in dogs and cats with certain restrictions, since it can be toxic and sometimes fatal to some breeds .

This medicine is used to treat heart Worm Disease (Heartworm) Scabies (Scabies and Demodecidose) and Scabies Ear (Otoacaríase) and control Intestinal worms.

The products sold under this principle are Cardomec ® , Ivomec ® ,, Endogard ® ,, Mectimax ® ,, Revectina ® , among others.

Unfortunately Ivermectin can not be used in dogs of breeds Collie, Shetland Sheepdog (Mini Collie), Border Collie, Sheepdog, Bearded Collie, Australian Shepherd and their crosses . In addition to these races there are those animals with a genetic alteration are also sensitive to the drug.

The most common causes of ivermectin toxicity are due to administration of excessive doses (10-20 times the recommended dose) and sensitivity of the race.

Very young animals, animals of the breeds mentioned above and animals with head trauma history or other diseases of the central nervous system affecting the blood brain barrier appear to have an increased risk of poisoning.

This feature allows the passage to the brain of ivermectin in low dosages, causing poisoning. Dogs that exhibit these characteristics can, in addition to Ivermectin, intoxication with other agents listed below, which should be avoided or used at lower doses in susceptible breeds according to avaliaçãodo veterinarian.

–  Selamectin

– Milbemycin


– Moxidectin



– loperamide

– acepromazine

– butorphanol


– Vinblastine


Toxicity may occur as a single dose or from daily doses.


Signals can occur in acute or subacute form . Acute signs often develop within 4 to 12 hours of drug exposure . The subacute signals often can occur 48 to 96 hours of drug exposure.

The most common signs are:

* Dilated pupils


* Depression


Excessive Salivation


* Tremors



* Disorientation


* Being supine (lying down)

* Blindness

* Slow beat of the heart.

* Anorexia (lack of appetite)

* Stupor

* Slow Breathing







* Eat or death


Diagnosis is based on possibilidadeou sure the medicine, being a sensible race medication and ruling out other possibilities for the neurological disorders mentioned above.

Nomalmente examinations and biochemical blood count are normal and only the gases may have changes consistent with respiratory depression.


The treatment is largely supportive and symptomatic , since no specific reversal agents available to treat toxicity of ivermectin . If the drug ingestion was recent (4-6 hours), we can induce vomiting and gastric lavage in order to eliminate the drug or decrease its absorption.


– Support Fluid (serum in the vein) and electrolyte replacement.

– Nutritional support for esophageal tube.

– appropriate bed, often changing position, physiotherapy, lubricant eye and urinary temperature control probe.

– Mechanical ventilation (breathing) may be indicated for those with difficulty in breathing.

– Anticonvulsant if necessary.


The prognosis depends on the severity of clinical signs, race and daquantidade of medicine used. Some pets may require days or even weeks of supportive care.


Only use medications with the prescribing veterinarian and be sure drugs to the animals ( many are palatable ). If you have a susceptible breed (described above), consider not using these drugs.

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