Multi-drug Resistance in Collies (MDR1)

Test Results in the UK are now on a separate page - see the menu on the left.

The Club is encouraging owners to have their dogs tested for MDR1 (a painless and simple procedure) and will be bringing a supply of swabbing kits to all our Club events. We are also encouraging owners to share their test results via the Club website - knowledge of our breed's health status is absolutely essential. Results of tests to date can be sent to Bev White at bevfrenchwhite@googlemail.com for inclusion on the site.
 
It is now widely accepted that the Collie breeds (Rough Collies, Smooth Collies, and Border Collies) appear to be hypersensitive to certain drug compounds.

The problem first came to light in 1983 when several Collies died from Ivermectin poisoning and, since then, the veterinary profession has accepted this drug should never be given to Collies. More recently a Rough Collie died from eating horse faeces (Ivermectin is used for worming horses and any excess drug passes out with their faeces).

Researchers have since found that approximately 60% of Rough and Smooth Collies appear to be susceptible not only to Ivermectin, but to a wide range of other drug substances. The MDR1 (multi-drug resistant) gene is responsible for enabling the body's blood-brain barrier to function normally. In healthy dogs the brain and central nervous system are protected by the 'blood-brain barrier', which prevents high drug concentration from circulating in the blood stream.

However, in MDR1-affected dogs the function of the blood-brain barrier is compromised allowing certain drug compounds to leak into major organs like the liver, or into the central nervous system, causing toxic reactions and even death. Symptoms include excessive salivation, ataxia, blindness, coma, and respiratory problems.

An MDR1 Normal dog (+/+) receives a healthy MDR1 gene from each of its parents and can therefore only pass on healthy genes to its offspring. The healthy + genes are dominant and such animals do not exhibit drug toxicity.

A 'Carrier' (+/-) is a dog that has received a normal [dominant] MDR1 gene from one of its parents, and a defective gene [recessive] from the other parent which is 'carried' by the dominant + gene. Please bear in mind that a carrier can pass either a normal or a defective genes onto its offspring resulting in approximately 50% of the puppies inheriting a defective MDR1 gene. Theoretically the 'carrier' animal should not be susceptible to drug toxicity but unfortunately the dominance of the MDR1 + gene has been found to be incomplete as some 'carrier' animals also appear to be susceptible to high doses of those drugs that cause problems in MDR1-affected dogs, that is, those with two defective MDR1 genes (-/-).

An Affected dog (-/-) receives a defective or mutant MDR1 gene from both its parents, so such dogs are double recessive and will display toxic reactions to a wide range of drug compounds (see list below). In 2007 a genetic test was made available for MDR1 and so it is extremely important that breeders try and use Normal (+/+) dogs in their breeding programmes so as to eliminate the defective MDR1 genes as soon as possible.

If you have an MDR1-affected Collie (-/-) you could be in a position to save its life by providing your veterinary surgeon with a copy of its MDR1 Certificate and the list of drug compounds that your Collie should never be given. Of those vets who have already been asked to put MDR1 test results onto a Collie's records, all have been aware of the Ivermectin problem but have had no idea about the broad spectrum of drug compounds that can severely threaten an MDR1-affected dog.

Please note there are usually alternative, safe drugs your Collie could be given instead.

The table here shows three classes of drug compounds: Class A includes substances that have been proven to pass through the blood-brain barrier in MDR1-affected dogs and cause problems; Class B lists substances which have shown interactions in animal tests, whereas Class C substances can be given without problems, even to affected dogs:

Laboklin (Manchester) carry out MDR1 tests at a cost of £70.00 per dog. DNA swabs are freely available from Mansour Makki
Email: m.makki@laboklin.co.uk (telephone 0161 2823066).

Please CLICK HERE to check web site for details and order forms etc.

For information - the Club has investigated costs of DNA testing for MDR1 and CEA/CH as the costs for laboratories used for UK clients are high and we have found an alternative.
There are several labs in Europe undertaking MDR1 testing at cheaper rates than Laboklin (which is interesting as UK lab sends all samples to Germany!) but Optigen appeared to have the monopoly on CEA testing.  However there is a lab in Czech Republic that is used by many breeders in Europe that offers both MDR1+CEA testing at considerably less and is available to residents in all EU countries.
 
Cost comparison (July exchange rate):
 
 
Optigen  CEA - £118.48
Laboklin MDR1 - £70.00 
Genomia MDR1 - £48.68; CEA - £66.22 MDR1 and CEA - £94.08

 The website for Genomia is www.genomia.cz and is available in English.  They also offer a discount for 5 or more samples. 

 
Also for information - if anyone has had their dogs tested for MDR1 through Laboklin using blood samples rather than mouth swabs, they can ask Laboklin (contact German lab direct by email) to send on sample to Optigen for testing.  Saves cost of second blood test and slightly cheaper than sending direct - Laboklin will invoice you but you do need original sample number (on results sheet).

Note: Please ensure you provide your vet with copies of all MDR1 test results so they can be added to your dogs' veterinary records.
See Sandra Schaffer and Marita von Dicken's database, where results are collated from all countries.