heartworm meds

[Cheryl Lynn]

I remember reading something in the past about border collies and Interceptor but I can't remember if it was to only give that brand or to never give that brand.Which one is it?

 

thanks for your help

[Pipedream Farm]

It makes no difference.

All heartworm meds will affect dogs the same way since all heartworm meds are in the same class of drugs. There are lots of threads on this issue; just search for heartworm or ivermectin to find them.

 

Mark

[Barb Scott]

Interceptor is supposedly more safe for BCs (and other collie-type breeds). We've used it for the last 15 or 20 years with good success. Heartgard contains ivermectin and can cause reactions in collies/collietypes.

Barb Scott

[Rebecca, Irena Farm]

We have two (related) dogs here that get sick from Interceptor. I've known for years that Ben barfed up his pills, since the time I moved his crate and found half a dozen half-digested pills that he had quietly barfed through the wire over the last several months. That was a scary trip to the vet. Ben gets ivomec now - my vet doesn't carry Hartguard.

 

Doug barfs them up too. Thankfully, I was alert for that possibility from the first he arrived - as I am with all new dogs.

 

I have another friend whose dog gets violently ill from Interceptor. It's odd that I happen to know so many Interceptor sensitive dogs but I've never heard of problems with ivomec. Maybe because a lot of the dogs around here are related.

[Pipedream Farm]

Originally posted by Barb Scott:

Interceptor is supposedly more safe for BCs (and other collie-type breeds). We've used it for the last 15 or 20 years with good success. Heartgard contains ivermectin and can cause reactions in collies/collietypes.

Barb Scott

Not true. Dogs that have the mutation making them ivermectin sensitive are also sensitive to ALL the heartworm meds on the market today. This is from one of the many posts refuting this rumor.

 

Hi,

 

Just ran through and saw this. Here's a general reply.

 

Important points to remember

 

1) The normal dose of ivermectin used for prevention of heartworm in products such as Heartguard (6 micrograms/kg) is not documented to cause the toxicity associated with this mrd1 mutation in collies or any other dog. It is only when higher doses are used, often by people mistakenly thinking the cattle/sheep dose is appropriate for dogs, that toxic symptoms appear in susceptible dogs.

 

2) Any of the avermectins, the class of chemicals ivermectin belongs to, are capable of producing the same toxicity in affected dogs when used at high doses. The commonly held belief that heartworm preventives such as Interceptor are safer than Heartguard is incorrect. Both products are safe at the low dose used. However, there are confirmed reports that moxidectin, which is used in the six month injectable for heartworm prevention, has caused neurotoxicosis in susceptible collies.

 

3) Any breed of dog can suffer from toxicity and death from ivermectin and the related class of drugs if they consume high enough levels to penetrate the blood-brain barrier. Levels of ivermectin shown to cause toxicity in beagles, a breed that does not have the mdr1 mutation are 2.5 - 40 mg/kg which is greater than 200 times the therapeutic dose.

 

Special considerations for farm dogs

 

An important consideration not everyone is aware of is that farm dogs often consume ivermectin or other avermectins in the manure from recently treated stock. Merck reports an apparent half-life for ivermectin of 1-1.5 weeks in sheep manure from sheep wormed with the standard drench dose of 200 micrograms/kg. They also estimate typical soil incorporation rates for manure from treated sheep to range from 0.16 ppb to 5.1 ppb. (From http://www.fda.gov/cvm/FOI/131-392FONSI.pdf ) Therefore, it?s possible for collies and other breeds known to have the mdr1 mutation to consume a toxic dose of ivermectin from eating the manure of recently wormed stock. The timing of worming stock with avermectins should also be taken into account when giving farm dogs heartworm preventative to prevent accidental overdose.

 

Partial list of drugs known or suspected to cause problems in dogs with the mdr-1 mutation

 

Ivermectin (antiparasitic agent)

Loperamide (Imodium?; over-the-counter antidiarrheal agent)

Doxorubicin (anticancer agent)

Vincristine (anticancer agent)

Vinblastine (anticancer agent)

Cyclosporin A (immunosuppressive agent)

Digoxin (heart drug)

Acepromazine (tranquilizer)

Butorphanol (pain control)

 

Partial list of drugs thought to have the potential to cause problems with the mdr-1 mutation

 

Ondansetron

Domperidone

Paclitaxel

Mitoxantrone

Etoposide

Rifampicin

Quinidine

Morphine

 

Reference: Neff, et al, 2004

 

 

As far as the internet reports on cases of ivermectin sensitivity in border collies, as I said, I contacted the people who do the gene test and they said no border collies had been confirmed to have the mutation. I asked specifically about the unconfirmed reports and they are still unconfirmed. The number of border collies that've had the test is now over 300.

--------------------

Denise

Mark

[Rebecca, Irena Farm]

If I had the money to blow, I'd test Ben to see whether it's the mdr-1 mutation that is causing the problem. I just realized, looking at the list, that there are two other drugs on there we've consistently had trouble with, in the past (Bute and Ace). Maybe in the spring when cash isn't as tight.

 

Is filaribits (diethycarbamazine) in the same class as the avermectins?