Posted 11 December 2002 - 08:08 AM
I'm a brand new mom to 2 7 month old pups, not siblings but we just couldn't pick one.
I've had standard collies before and know they're sensitive to ivermectin. Are Border Collies also sensitive to it? What is commonly used?
Posted 11 December 2002 - 08:39 AM
Posted 13 December 2002 - 10:05 PM
is he in danger of a reaction to Heartgard after being on it this long, is it cumulative or would it be safer to discuss change with the vet? He seems to tolerate the Pill form ( wouldn't take the chewables at all)
Posted 14 December 2002 - 03:05 AM
My feeling is that nearly any drug CAN settle in the tissues - after all, that is where it does it's work, isn't it?
Changing to Interceptor should not be a problem, it's just another type of heartworm drug.
I always discuss things with my vet, but make up my own mind.
The two situations where I know of harm and death to dogs through Ivermectic were NOT cumulative, btu with the rising rate of cancer and seizures and "stuff" in ALL dogs, I suspect we are doing something that isn't truly working...
Dr. Goldstien has a good book, "The Nature of animal healing" that discusses some of this stuf...and www.altvetmed.com has some good contact info...
One thing I would mention is that even if your dog is on heartworm preventive 12 months a year you should still test - again, there are cases where dogs were on the preventive and still had heartworms.
Kensmuir, Working Stockdog Center
River Falls, WI
[This message has been edited by PrairieFire (edited 12-14-2002).]
Posted 16 December 2002 - 02:26 AM
General information: http://petplace.nets....asp?artID=1525
tells the drug is excreted in feces and has a 1/2 life of 24 - 36 hrs. Somewhere else I read that a very small amount is metabolized by the liver.
Gene that produces sensitivity: http://www.vetmed.ws.../ownerInfo.html
The reported sensitivities (scientific papers) talk about collies, collie crosses, and Australian shepherds; I've not seen "border collies" specifically listed but that doesn't mean sensitivity does not occur (just not reported in scientific papers).
Based upon these papers (and others) Invermectic is cleared from the dog's body within a month, at least to below the detection limit of the analytic method used. This link shows that plot for injected Ivermectin in cattle, while the cattle dose is much higher (100x that of the dose for a dog) and a cow's system is different than a dog's it gives you an idea of how the drug level in the body changes over time.
Since the drug does clear for the body, changing to Interceptor shouldn't be a problem. Since the sensitivity appears to be genetic, I wouldn't expect your dog to develop sensitivity over time.
Posted 17 December 2002 - 02:37 AM
do you use Ivermectin for your livestock? I would think you'd avoid its use altogether if you're worried about sensitivity to it in your dogs, since your dogs can injest it via your livestock's feces.
Just a thought.
Posted 18 December 2002 - 06:40 AM
Black Dog Farm
Posted 18 December 2002 - 06:48 AM
I've just been wondering how many of the border collies that show sensitivity to Ivermectin were in fact a reaction to an unintentional overdose via Heartgard plus "sheep cookies" from Ivermectin treated sheep.
Posted 18 December 2002 - 08:11 AM
I have used ivermectin for heartworm control in all of my Border Collies (5), and have never had any problems. The risk of Collie-type ivermectin sensitivity in purebred Border Collies is very very low. I don't have an accurate incidence rate for you, and I certainly will not claim that the risk is nonexistent, but none of the small animal vets I've worked with at 2 different university teaching hospitals have ever seen it in a Border Collie. I do think twice before using a full anti-parasitic dose (which is more than 30x higher than the dose used for heartworm prevention), but have also done this safely on numerous occasions when it was warranted. Whenever I use this dose for the first time in a given dog, however, I watch the dog very closely over the next 12 hours or so.
Now that the genetic basis of Collie-type ivermectin sensitivity has been identified, it is likely that the genetic test will soon be made available to interested dog owners. For a one-time fee (probably around $50 or so) you could buy both peace of mind and a lifetime of savings on heartworm preventatives. Given the high price of alternative drugs such as milbemycin (Interceptor), the cost of the test would be quickly repaid, assuming of course that your dog is negative for the mutation in question.
The overdose issue is a completely separate concern from Collie-type sensitivity, which is caused by greater than normal accumulation of ivermectin within the brain due to a genetic mutation in specific drug-transporting molecules. ALL animals are susceptible to ivermectin overdose (dogs with the sensitivity mutation even more so, of course). Here at the University of Minnesota, for example, we treated a foal for a near-fatal overdose recently - it had received about 20x the recommended dose. Since preparations for cattle, sheep, and horses are more concentrated than those used for dogs, relatively small volumes can be dangerous so safe storage and disposal of these products is important.
One final point that I think it is important to clarify:
Current evidence indicates that the recommended dose of ivermectin for heartworm prevention (e.g. the dose in Heartgard: 6 micrograms/kg body weight) is safe EVEN in those Collies that possess the mutation conferring unusual sensitivity to the drug. All of the reported cases of ivermectin toxicity in Collies and other breeds were associated with administration of significantly higher doses. Either the owner or vet had accidentally miscalculated the dose, or the much higher anti-parasitic dose had been administered (200 micrograms/kg body weight).
** Note: my comments should not be construed as a blanket recommendation for the use of ivermectin in Border Collies! I am comfortable doing so and have never had any problems, but your mileage may vary. Please consult with your own veterinarian before making major decisions about your dogs' medical care.
Cheers and Happy Holidays to all!
[This message has been edited by CMalazdrewich (edited 12-18-2002).]
Posted 18 December 2002 - 08:14 AM
Black Dog Farm
Posted 19 December 2002 - 07:49 AM
Dr. Katrina Mealey at Washington State University is the researcher that identified the genetic basis of ivermectin sensitivity in Collies and developed the genetic test for the underlying mutation. Yesterday I contacted her to pick her brain for any information she may have regarding incidence of this mutation in Border Collies. Although she has not yet been able to conduct large-scale testing in this breed due to a lack of sufficient funding, her preliminary studies have failed to identify the mutation in any Border Collies. Nevertheless, she suspects that it may still be out there. She has identified the mutation in several Aussies. Part of the problem is that they have not been able to find any ivermectin sensitive Border Collies to test.
There is a way you can help science to continue its forward march, as well as contribute to the Border Collie community! If anyone on the Boards owns or knows of a Border Collie that has shown signs of ivermectin sensitivity, Dr. Mealey would be VERY interested in testing it (free of charge). The test is run on cells collected from the inside of the dog's cheek with a small swab/brush. She will mail the swab and instructions directly to you, and you can mail it back to her after collecting the sample. Interested parties may contact Dr. Mealey directly at the following e-mail address: firstname.lastname@example.org
For those of you who may be interested in testing your dogs as a precaution, Dr. Mealey indicated that her genetic test will be commercially available some time in the upcoming year. I will keep in touch with her and post additional information when it becomes available.
Posted 19 December 2002 - 08:29 AM
very interesting stuff. Please keep us informed. Unfortunately (or fortunately) we don't have any ivermectin sensitive dogs.
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