Midland Collie Club

Many of you know that Collies must not be administered Ivermectin as it can cause serious troubles and even death. Recent research findings from Germany and the United Stated show that a genetic defect is the cause of this oversensitiveness and that more drugs can cause troubles. Read this summary by Raymonde Bergmann
Important information: Genetic defect in Collies can cause oversensitiveness to drugs:
Ivermectin sensitiveness is connected to a genetic defect of the blood brain barrier.
Already in the 80ties, it was reported that Collies showed neurotoxic effects after administration of Ivermectin.

In the past a few breeders lost many of their dogs because not all vets were aware of the toxic effects this medication could have in Collies.

Recently scientists in Germany and in the United States discovered a genetic defect causing this over sensitiveness. The defect concerns the Multidrugresistance-1, short MDR-1 transporter.

The MDR-1 transporter is located on surface from the liver, kidney, intestine and brain cells. It is responsible for the transport of certain molecules. Scientists discovered it on cancer cells that showed resistance against several chemotherapies.

On the border between blood vessels and nerve tissue the MDR-1 transporter puts up a defense barrier for the brain which is a part of the blood-brain-barrier. The MDR -1 transporter usually is located on the surface of the Endothelial cells , which cover the inside walls of the blood vessels.

When all is working properly in this area the MDR - 1 transporter insures that no toxic substances like Ivermectin can penetrate into the nerve tissue. In case of a genetic defect in MDR - 1 this protection function gets lost and toxic substances can enter straight into the nerve tissue in high concentrations. Such a defect of the blood brain barrier is causing in affected dogs strong neurotoxic side effects after administration of Ivermectin.

They suffer from troubles in coordination and movements, trembling, dizziness, their pupils are enlarged, there is more salivation and it can come to death. Nowadays it is also known that there are several more medications that can cause troubles in affected Collies and can enter the brain at a rate 90 times higher as on those animals with a sound blood brain barrier. Here is a list compiled from the findings of the University of Giessen and from the American Scientist Mark Neff.

Worming medications
Ivermectin
Selamectin
Moxidectin
Cardiac drugs
Digoxin
Quinidine
Gastro-intestinal drugs
Loperamid
Domperidon
Immuno-suppressants
Cyclosporin A
Tacrolimus
Steroids
Dexamethasone
Hydrocortisone
Anti-Cancer agents
Vincristine
Vinblastine
Doxorubicine
Narcotics
Ondansetron
Antimicrobial agents
Erythromycin
Grepafloxacin
In UK they found that Immodium contains also small doses of Ivermectin and from Holland the news reached us that a new worming medication named Verminthel (containing Abamectine) caused also death to one Collie and one Sheltie.

At the moment it is believed that the defect is transmitted in a recessive way. The defect can be tested with a blood sample. That way it can be determined if your dog has the defective gene or if he is a carrier or if he is free from this defect. Certain reports show that probably also Bearded Collies, Border Collies, Old English Sheepdogs, Shetland Sheepdogs and Australian Shepherds are affected.

You can read the full publication of the Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California.
By Raymonde Bergmann, August 21st 2004