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How to Buy Cheap Heartworm Preventatives Without a Prescription

Dr. Mark is a veterinarian. He works mostly with dogs and exotic animals.

Heartworm medications are available at your nearest vet's office.

Heartworm medications are available at your nearest vet's office.

Cheapest way to Treat Heartworms

Can you buy heartworm prevention for your dog for less than 10 dollars a year? Sure you can.

Heartworm preventative is a big expense for everyone that keeps dogs. It should be readily available to everyone, no matter what their income is, since it is a terrible disease. It's worse than many others because it is so easy to prevent.

Why Is Heartworm Preventative so Expensive?

The big drug companies that sell heartworm preventative make a healthy profit off of their products and are not about to help owners find a cheaper option. I do not have stocks in these companies, do not market their products, and do not mind if you find an alternative. What I care about is seeing that all dogs are healthy, and I would like to give you this alternative that I use.

What is the alternative? You can prevent heartworm disease by using the same medication that is sold by the drug companies for a fraction of the price. If you have a large dog, you can order the generic ivermectin from (I have large dogs, so this is the form of ivermectin that I give them to prevent heartworm disease.) The cost of a 50cc bottle is about equal to a six-month box of heartworm preventative (or much less, depending on where you are buying your preventative). When the generic ivermectin arrives, it should be kept in the refrigerator. The expiration date is about three years.

The Ivermectin Dose

Quite a few of the doses listed for generic ivermectin on the internet are absurd and the label on the most common heartworm preventative is only 0.006 mg/kg. Since ivermectin is sold at 1%, or 10mg/cc, a 20 kg dog needs less than 0.05cc. Even when you are giving the dose to a big dog, the ivermectin dose is so low that it needs to be drawn up with an insulin (diabetes) syringe.

The only insulin syringes I can find online with a needle are for sale only as a full box, and you do not need to buy 100. You really only need one. There are larger syringes for sale with needles, but you cannot use a large syringe to dose a dog. I would recommend you try to buy a single insulin syringe with a needle from a local pharmacy. It would be cheaper and more accurate. Since the insulin syringe does not need to be sterile, you can reuse it. I keep mine in the refrigerator next to my ivermectin. I do not have children at my house, so I do not need to worry about the syringe in the refrigerator. If you need to be concerned, please keep it out of reach of children.

Can I Use the Syringe Every Month?

There might be some concern out there about reusing the needle and drawing up a small amount every month. The medication should be kept refrigerated to reduce bacterial growth. Most importantly, the ivermectin should only be given orally.

Dogs have a lot of healthy bacteria population flourishing in their gut and a small dose on a dog biscuit is not going to affect them. If you needed to give this medication on top of a dead and rotting squirrel each month, I would be concerned about GI upset; a drop on a little biscuit does not worry me.

What About a Small Dog?

If you have a small dog, the ivermectin available for cattle is much too concentrated. There are several options to make it more diluted. You can make up a 30:1 dilution using propylene glycol. At this dilution rate, 0.1cc contains only 333 micrograms of ivermectin, so it is easy to dose a small dog at 0.1 cc per 10 pounds. The site recommends mixing 0.1 cc of ivermectin 1% with 3 cc of propylene glycol.

The only problem with that is buying the propylene glycol, keeping an extra 3 cc syringe around for dilution purposes, and having another container to keep the dilute ivermectin in.

The other option is to use the 0.08% ivermectin drench for sheep. It is the same product I use for my large dogs. An eight-ounce bottle is enough to treat a 100-pound dog hundreds of times. If you have smaller volumes available, or want to divide up a bottle with your neighbor, it will not be any more expensive than the product marketed for cattle. There is a two-year expiration date, so even if you had to buy a bottle by yourself, it would only cost about $15 per year.

Dogs only need about 3.5 micrograms per pound to safely prevent heartworm disease, according to the makers of Heartgard, but due to some recent research done at Auburn, I am including the dose for about 7 micrograms per pound. Since one milliliter of the sheep product contains 800 micrograms, here is what you only need to give.

Dose of sheep drench ivermectinWeight of the DogNumber of Micrograms

0.1 ml

up to 12 pounds

80 micrograms

0.2 ml

12-26 pounds

160 micrograms

0.3 ml

27-50 pounds

240 micrograms

0.4 ml

51-70 pounds

320 micrograms

0.5 mll

71-90 pounds

400 micrograms

0.6 ml

92-112 pounds

480 micrograms

Do I Have to be Very Careful With the Dose?

Since you are using such a small amount of this drug, you could even double the dose and still only use a tiny amount. There is a comment in the advertisement about this cattle ivermectin being dangerous for dogs. If it is given as an overdose, it will be dangerous. Ivermectin is used at a much higher dose when treating demodectic mange (0.3-0.6 mg/kg) and for a long time, an average of 3-8 months. It is quite safe even at those levels.

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It would be more economical to treat the larger dogs with the cattle ivermectin, but if you have small and large dogs, the sheep product is easier to use. You can decide which product is right for you.

When the correct ivermectin dose is drawn up, you can put it on a dog biscuit or other dry food that your dog likes to eat. The volume of medication is very small but be sure to put it on a treat (something stinky!) where she will not notice the smell.

Can Ivermectin Cause Problems in Some Dogs?

Owners of Collies, Shelties, OES, Aussies, and some other mixed breed dogs might be sensitive to ivermectin. If your vet has been reluctant to prescribe heartgard to your dog, and you are concerned in any way, you can test for the mutation on the MDR1 gene that causes sensitivity. Testing is available though the Washington State University College of Veterinary Medicine.

Of course, these dogs can be given heartworm preventatives that do not utilize ivermectin (Revolution [selamectin] and Advantage multi [moxidectin] are both topical so treat fleas as well as preventing heartworm disease). Both of these medications are fairly new and will need to be purchased from your veterinarian.

Ajej and Achilles playing on the beach.

Ajej and Achilles playing on the beach.

Is Heartgard Plus Better Than Ivermectin?

Heartgard Plus contains ivermectin as well as pyrantel pamoate, a dewormer. This is one of the cheapest dewormers on the market, used to treat roundworms in puppies. Roundworms may not even be an issue in adult dogs unless they are nursing. The drug also treats hookworms, a more important parasite and one that should be controlled.

Effective dewormers can be bought without a prescription. Even if your dog was continuously exposed, it would still be cheaper to buy these drugs separately.

Dogs exposed every day, year-round

Dogs exposed every day, year-round

Closing Thoughts

If you have a small dog, are nervous about drawing up the ivermectin into a syringe, if you are afraid to figure out the dose for your dog, or if you believe the advertisements and think that the branded product is safer than generic, then you are better off paying a little more and buying the product sold by your veterinarian.

This method is not as easy as picking up a package and giving your dog a chewable every month. No matter what method you use, please continue protecting your dog however you feel is best.

This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.

Questions & Answers

Question: Do I have to make sure my dog doesn’t have Heartworm before giving her the ivermectin? Also, is it a once a month dose?

Answer: Ivermectin is used in the "slow kill" method to treat dogs that have heartworms. So no, you do not have to be sure your dog is heartworm negative before starting the preventative.

Some vet techs/vet receptionists will tell you that you can kill your dog if you give heartworm preventative without having a heartworm test first. This is not true. In the 70s and 80s we used a medication called Filaribits, and if the dog was not heartworm negative before prevention was given he could have problems. This is not the case with ivermectin.

The ivermectin only needs to be given about every 45 days. The reason that companies recommend once a month is so that people do not forget. (Always give heartworm preventative the first of the month, etc.) If they tell people every 45 days, dogs are more likely to miss a dose, be given medication late, etc.

So yes, it is okay to give it once a month. Try the first of each month.

Question: We live in Georgia and have a 60 lb. vizla/hound mix and an 80 lb. Labrador. They were both taking Trifexis. This took care of heartworms, fleas, and hookworms etc... What would be better the generic ivermectin or the sheep drench? And can you tell me the dosage for each of them in the suggested product?

Answer: Since you mention you live in Georgia, I would first want to recommend that you ask your local vet if ivermectin resistant heartworm is in your area. If it is, neither of these products are reccomended. Trifexis costs a lot more but as of this time no heartworm microfilaria have built up a resistance to this drug.

If you are going to use the ivermectin in your area, the generic ivermectin and the sheep drench contain the same drug. The sheep product is easier to use since it is not as concentrated, so I would suggest you use that. A bottle will last you several years, and if you share it with a neighbor you can use the doseages that I refer to in the article.

The smaller dog will need to get 0.4 cc and the larger dog 0.5 cc. This dose is small and should be given with a tb syringe (1cc).

If you buy a bottle of the ivermectin for cattle, (the generic product) even a large dog like the Lab only needs 0.024 cc. This is less than 0.05 cc, which is really the smallest dose that you can actually give.

You would need to make up a 1/30 solution to use the cattle strength ivermectin. To do so, add 1cc of ivermectin to 30 cc of olive oil. Mix thoroughly. At this dilution the Lab will need 0.7cc, the Vizsla 0.5 cc. This one ml of ivermectin will last you about 2 years.

Question: I mixed the dose of sheep drench with a blob of peanut butter and she ate it right up. My question is, you say to use a dry biscuit which she would never eat with the medicine on it. Did I make a mistake by using a moist media instead of a dry one for giving my dog medicine?

Answer: I just suggest using a dog biscuit since it is easy and most people have biscuits in the house. If your dog likes peanut butter instead that is great. Anything that masks the taste helps a lot.

Question: Do you have to dilute the sheep drench ivermectin like you do with the cattle pour on?

Answer: The doses that I list for the sheep drench are for the undiluted product. No, you do not need to dilute it any futher.

Question: I do not know if I can give the heartworm injectable formulation orally. Are the oral and injectable formulations the same drug?

Answer: The active component, ivermectin, is the same. The carrier molecule in the injectable solution is propylene glycol. This compound has been tested by the US FDA, and is generally listed as safe. It is used as a replacement for ethylene glycol in those "pet-safe" antifreeze solutions that you can buy. Would it be okay to give a couple of liters of propylene glycol orally? No, probably not. In this formulation, you are giving a very, very tiny amount.

As far as the sheep drench, it is an oral product. If you look at the dosing recommendations, you will see that it is a very tiny amount. If you have any doubts about this, I suggest you continue to buy the oral product that is sold through your vet. after all, it went through a 30-day test.

Question: I live in Georgia. I have a 130 lb dog. What dose of ivermectin would I give him every 1st of the month? Would I put it on his food or inject him?

Answer: In a separate container, add 1 ml (cc) of the ivermectin and 30 ml of olive oil. Shake it up so that the ivermectin is mixed thoroughly. When you have made up this solution, give your dog 1.1 cc of this solution on the first of every month.

It is better to give him ivermectin directly into his mouth so that he does not spit it out/refuse it. Sometimes they will do that since the medication tastes bad.

Since you are in Georgia, I do want to advise you that there has been ivermectin resistant heartworm discovered in some places in the south. Talk to your local vet and find out if this is a problem where you live. If it is, one of the other products may be safer. They will, of course, be a lot more expensive.

Question: What do you recommend for intestinal parasites and fleas if changing from Trifexis to ivermectin?

Answer: It depends on what kind of parasites. The product in Heartgard, pyrantel pamoate, does not kill all parasites but is okay for roundworms. If you want to use that, you can purchase it VERY cheaply from Amazon. I think the best thing to do, however, takes your dogs stool sample to his regular vet a few times a year and have him checked for worms. It is likely that he will not even need any kind of treatment.

Fleas are another matter. If you live in an area where fleas are a big problem, it might be cheaper to use a medication like Triflexis that gets the fleas and prevents heartworm. If fleas are not much of an issue, you can use an over the counter topical (like Frontline or other inexpensive topicals sold in pet shops) or use natural flea control methods like a flea comb, vacuuming, and diatomaceous earth.

It depends on how big a problem fleas are, and how much you or the dog are bothered by them. I know some clients get upset if they see one flea.

Question: My vet has been treating my twelve-year-old Australian female for heartworm for two years at least. She has been given shots 3 different times to kill the babies but nothing that effects the adult works. Is there anything else besides the regular monthly heartworm treatment?

Answer: I am not sure if the vet is using a very low dose because of safety concerns, the condition of your dog, etc. It is impossible for me to say since I have not examined your dog.

If this is taking so long, the alternative is the slow kill method. You use monthly heartworm preventative year round to kill any new babies. The adults die off by themselves. Please reference this article:

I do not think you should give your dog any more injections to kill the adults.

Question: I have two medium size dogs; one is 47 lbs and the other is 56 lbs. Would the dosage of ivermectin be 0.05 ml? Does this have to be injected, or can it be digested, via giving with food?

Answer: The cattle strength ivermectin is more difficult to dose for small and medium-sized dogs, so I would recommend you purchase the sheep drench instead. The correct dose for your dogs would be 0.3 ml for the smaller and 0.4 ml for the larger dog. The oral sheep dewormer is very affordable.

Both solutions, the cattle and the sheep product, can be given orally, just like Heartgard from Merial. It should NOT be injected.

© 2012 Dr Mark


Dr Mark (author) from The Atlantic Rain Forest, Brazil on August 16, 2020:

Jan, it is really necessary in some areas. When I worked in the Mississippi valley I saw many dogs die of this painful disease. Other parts of the US never have a problem.

It is one of those situations where the costs are not worth it, until they are. It is a horrible way for a dog to suffer and die.

Jan on August 16, 2020:

We’ve always had dogs never have given heart worm pills even to our outside dogs never had any of our dogs get Herat worms ...we’ve had 5 dogs at one time have one indoor dog I just was wondering is it really necessary?

Dr Mark (author) from The Atlantic Rain Forest, Brazil on May 13, 2020:

Dexter, just go into Amazon and add this into the search: 1ml 1cc Syringe with Luer Slip Tip, No Needle, Sterile (Pack of 50)

That is the box of 50, about $6, or you can probably buy 1 one cc syryinge at a local feed store.

I Dexter on May 13, 2020:

Dr. Mark, I'm confused about what type of syringe to get for the sheep drench ivermectin. I have a 16lb schnauzer, so I understand I need to give .2ml, correct? I just don't know the proper syringe to buy (U40, U100, etc.) Any chance you could provide a link to the right kind just so I know (even if it's a box of 100)? Thanks so much forthis article!!! I have been using Nuheart for 6 years, but can't get it because of the Covid19 pandemic!

Dr Mark (author) from The Atlantic Rain Forest, Brazil on August 06, 2019:

Annalyn, no, I just stopped the chart at that number because it is so unusual to see a dog over 112 pounds. If your dog weighs that much you can go ahead and give 0.9cc safely.

Annalyn Paz on August 06, 2019:

Is there a maximum dose currently used? My dog weighs 160 lbs and is very lean.

Dr Mark (author) from The Atlantic Rain Forest, Brazil on January 18, 2019:

Peg, no, it is not. It is very concentrated, and you are most likely going to overdose and kill your dogs, unless they happen to weigh as much as one of your horses.

Buy the medication in the sheep strength. It is worth it to avoid the potential heartache.

Peg on January 18, 2019:

Is Bimecten 1.87% (what I use for my horses) safe to substitute for the Ivermectin?

Dr Mark (author) from The Atlantic Rain Forest, Brazil on October 19, 2018:

Samantha, currently doxycycline is recommended for secondary Wolbachia infection. Some vets even think that this infection is responsible for most of the side effects.

Samantha S Heinz on October 19, 2018:

I work with an animal rescue in NC. I have been mixing ivermectin heartworm preventative for many years. Several local vets have checked my "recipe" and found it to be accurate. I use the 1% ivermectin and dilute 2.5 ml with 40 ml of an oil based skin and coat supplement. It tastes better if it has salmon or cod liver oils. The dose of the mixture is 1 ml per 50# dog. We have diluted further for small dogs as it is still hard to give such a tiny amount. This will separate and has to be shaken well before drawing up the mixture to give.

One local vet also told me that if this mixture is given at 1 ml per 5# it will kill roundworms, hookworms and whipworms. We do not give this amount to herding breeds that might be ivermectin sensitive or to heartworm positive dogs.

When funds were especially low, we have used this ivermectin dose as the slow-kill method of heartworm treatment. We gave the preventative dose every 2 weeks and all dogs tested negative when checked at 6 months. If people use the slow-kill method, do you recommend giving doxycycline to kill the Wolbachia parasite that lives symbiotically with them? This is the current practice of our local vets.

Dr Mark (author) from The Atlantic Rain Forest, Brazil on June 16, 2018:

You do not need a prescription to purchase ivermectin through Amazon.

DividendRaptor on June 15, 2018:

Have you used any of those websites you have listed to purchase pet meds with no prescriptions? Please point me in the right direction as there is a lot of bad reviews out there.

Dr Mark (author) from The Atlantic Rain Forest, Brazil on June 15, 2018:

Cassaundra, yes, you can keep it in your fridge.

I have big dogs too and use it without diluting. The problem is though that the 1% ivermectin has a very low dose. (For your dog, for example, would only receive 1/30th of that 1.1 cc dose)

You can give it orally, without diluting it, but if you give too much an overdose is more possible. (Since I give very large doses for dogs with demodectic mange I do not worry about this.) If I were to recommend people give a larger dose, and the dog got sick or died from the ivermectin, I would feel responsible. Maybe not legally, but definitely morally.

If you still want to give the undiluted ivermectin, I would recommend you use a dropper bottle. Your dog would only need one drop once a month. As you can tell, a bottle of this ivermectin is going to last you a long time, as long as the expiration date.

Cassaundra Green on June 15, 2018:

Thank u so much for ur reply.. I just have a couple other questions..once I mix the 1ml (cc) of ivermectin with the 30ml (cc) of Olive oil and give my 130 lb fur babe 1.1 ml (cc) of this solution..should I keep this mixture and store it in the fridge for the next month or toss it? Can I ever just give my fur babe the ivermectin without the olive oil? If so what dose?

Dr Mark (author) from The Atlantic Rain Forest, Brazil on May 02, 2018:

Paige, Alabama is a grey area. Most of the heartworms that are resistant to ivermectin have been found in the Mississippi valley and Georgia. I can understand what you are saying about the grain allergy, but you really need to talk to a local vet and find out if any of the dogs on Heartgard have had problems. If not, the sheep drench is okay. If they have, the sheep drench should not be used.

Paige on May 01, 2018:

I have a pit bull 3 years old and is 80lbs we live in Alabama do you think sheep drench would be a good option For him? We are trying to save money any way we can due to him having a grain allergy And having to buy expensive dog food

JeanieD on October 17, 2017:

I found Sheep Drench at Tractor Supply. Sighuff, do you have Tractor supply in your area?

Dr Mark (author) from The Atlantic Rain Forest, Brazil on October 04, 2017:

I think the sheep drench was on there but HP took it off. It is available on Amazon, but you can also get it at a feed store. Do you have any around where you live in Fl?

That Triflexis sounds really expensive. As far as treating worms, the only times dogs drag their end because of worms is when they have a tapeworm infection. You can find little white segments-similar to grains of rice-so I cannot see it happening every month. Ask your local vet if tapeworm infections are a big problem in your area.

Sighuff on October 04, 2017:

(Also, I don't see where to buy the sheep drench?)

Sighuff on October 04, 2017:

Trifexis costs me $24 per month per dog (so $72 per month for all three). Three days after they "miss" their Trifexis, they're all scooting on the ground, so I think they do need to be de-wormed monthly. Do you still think Trifexis is the cheapest route for me?

Dr Mark (author) from The Atlantic Rain Forest, Brazil on October 04, 2017:

Sighuff, if you are in Florida, the triflexis may be the better buy for you, depending on what you have to pay. I live in the tropics and use natural flea control, treat for internal parasites only as needed.

The generic ivermectin is once a month, and for dogs even the size of yours the meds are hard to measure, which is why I recommend the sheep drench.

Sighuff on October 04, 2017:

I'm just not completely clear on the dosage for the generic ivermectin injection (the bottle shown, that links to Amazon for purchase). I have a 64 lb dog, a 69 lb dog, and an 84 lb dog. Also, this is still once a month, correct? Finally, my dogs are currently on Trifexis year round (we live in Florida). What can I use for deworming and flea prevention that will work here? It's a BIG issue where I am. Thanks in advance!

Dr Mark (author) from The Atlantic Rain Forest, Brazil on August 04, 2017:

Lauralee, since you are in that state (my jees are not workin on this PC! the ivermectin in Nuheart may not be workin. the dose is okay in other states up north. Read up on resistant heartworm infections, and talk to your local vet to see if it has been dianosed in your area.

Keep up on the alternative flea prevention!

Lauralee on July 26, 2017:

Hello! I have a 4 year old yellow lab weighing approximately 65-70 lbs. She has been on Nuheart (large dog) since August 2015 when we adopted her. She tested negative in 2015 and in 2016. Based on reading another of your articles, I am considering not getting her tested this year, but still continuing on the Nuheart which I buy from Australia. My question is concerning the dose of Ivermectin in Nuheart. Each once-a-month pill is 272 mcg. Will that be effective or should she receive more? In case it's important, we live in Georgia.

Also, we have stopped using topical flea/tick treatments this year (even though the ticks have been horrendous due to a very mild winter). I have started giving her brewer's yeast tablets with garlic and also 1-2 cloves of garlic a day, plus a couple of tablespoons of apple cider vinegar in her water bowl.

Many thanks!!

Dr Mark (author) from The Atlantic Rain Forest, Brazil on May 10, 2017:

Thanks SmartandFun, I appreciate your comments and interest. A lot of the damage from HW may be from the Wollbachia bacteria, which is why the doxycycline may be helpful in many of the cases. We learn all the time, and HW is not killing as many dogs as it used to when I started out back in the 70s.