Heart Worms & Using Ivermectin On A Modified Schedule
Yes, Heartworm Disease is a serious disease. And completely avoidable. You should be proactive about treating (preventing) your dog from becoming infected with adult heartworms – you do this by killing the microfilaria.
There is no “preventive” medicine for Heartworm. We are all treating microfilaria already infecting our dogs body to prevent growth of the microfilaria from maturing into adult heartworms, reproducing and becoming heartworm disease. ALL heartworm medicines work the same way – they kill heartworm microfilaria present in the body of the dog.
Heartworm medications do not prevent your dog from being infected with microfilaria.
Heartworm “prevention” medicines are TOXINS.
- The traditional drugs used to kill heartworm microfilaria are:
- Ivermectin: (Heartgard, Heartgard Plus, Iverhart, Merial and Verbac)
- Milbemycin (Interceptor, Safeheart, Sentinal and Norvartis).
- Both drugs are nematode poisons, and in both cases a single dose will kill all microfilarial infection that occurred up to 90 days earlier
- Read the package insert of any product you are you choose to use with your pet.
Ivermectin use in Dog’s With Seizures
Dr. Robert Clemmons of the Chi Instituted has noted that dogs with history of seizures do not fair well on Ivermectin. It would be best to consider Interceptor or AmberNaturals HWF.
Some breeds are more sensitive to Ivermectin.
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Some lines of collies and collie-crosses have sometimes fatal reactions to ivermectin, the most common heartworm preventative medicine. Though this is not common, and is even rarer today with low-dose Ivermectin such as Heartgard, and seems to only hold true for collies, serious thought needed to be given to dosing any collie, collie-cross, or herding dog with white feet. For these dogs, the safest heartworm medicine is Interceptor, though in fact the Heartgard box features a Border Collie on it face, and many working Border Collie folks dose their own dogs with a low dose of sheep drench 0.08% Ivermectin.
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Other breeds may also be at risk:
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Collies (e.g., Border Collies, Rough Collies, Shetland Sheepdogs)
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Australian Shepherds
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Old English Sheepdogs
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Long-haired Whippets
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Silken Windhounds
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McNabs
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English Shepherds
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If your dog belongs to one of the susceptible breeds or has tested positive for the MDR1 gene mutation, it is important to inform your veterinarian so that alternative medications or dosage adjustments can be made to ensure their safety and prevent potential ivermectin toxicity
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However, the dosing amounts for seasonal hw is significantly lower than dosing for Mange, Heartworm Treatments, etc.
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The Heartworm Cycle
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After a infected mosquito bite, it takes about three months for microfilaria (baby worms) to grow inside your dog to a larval stage, and even longer for these larva to mature into adult heartworms.
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If your dog is dosed with a simple Ivermectin treatment at any time during this period before adult worms are present (a period that lasts about three months long), the larvae will never develop into adult worms, and will die. Read that statement again: a single dose of Ivermectin will stop heartworm dead up to 3 months after your dog is first infected.
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Heartworm is a kind of nematode (dirofilaria immitis) spread by mosquitoes (and only by mosquitoes). The lifecycle of the nematode involves six stages, and a dog can get infected with heartworm only if two of these stages are fully completed inside the body of the mosquito, and those stages
- can only be completed inside the body of the mosquito if the temperature stays ABOVE 57 degrees for at least 45 days straight, both day and night. If the temperature drops below 57 degrees even once during that 45-day period, the lifecycle of the nematode is broken, and heartworm cannot be transmitted to your dog.
- What this means, in simple terms, is that a year-round program of Heartgard (sometimes spelled 'Heartguard") or some other “preventative” medicine is NOT needed in most of the country.
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Most people feel comfortable with the first dose of spring once we hit that 45 day mark of 57 degrees, and then 45 day intervals
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The Last dose can be administered 45 days after your temperatures start falling below 57 degrees in the fall.
- For me this translates to a first administration in June and the last in November.
Assess Your Region:
Some regions will seldom ever see a case of heartworm disease. For some of us in the south, we have this completely preventable disease take the life of too many dogs in a very tragic way.
As you consider the climate requirements above AND the fact that heartworm preventatives don’t prevent, but rather kill microfilaria already in the body to prevent growing into adult heart worms – you may start to feel comfortable modifying your schedule.
Testing for heartworm Before or While Using Ivermectin
I’d recommend all of you continue your annual heartworm testing. Making the change to alternative remedies makes many nervous and you’ll want to be reassured that your decision to change is working.
Shelter Dogs, Rescue Dogs, Strays, etc should be tested before beginning any strategy.
- Puppies under 6 months do not need to be tested. A puppy, under six months of age, of course, will always test negative for heartworm because the microfilaria have not yet had a chance to develop and circulate.
Dogs with Heartworm Disease
- It does not have to be expensive and overly complicated to treat a dog with heartworm disease
- Yes it’s risky for any dog with heartworm disease, but we have to try! If the dog appears healthy (i.e. it is active, not lethargic, and does not have a chronic cough), a monthly dosing of Ivermectin at a dosage normally used to kill roundworms (a dosage that is 3 times higher than that used to simply prevent heartworm), plus a once-a-month 5-day dosing of Doxycycline (sold as Bird Biotic, and the same antibiotic used to treat Lyme disease) will kill all the adult heartworms if it is sustained for a period of 18 months. This treatment works better than previous Ivermectin-only treatments because the Doxycline wipes out the Wolbachia microbe that grow in the gut of the adult heartworm, essentially sterilizing all of the female heartworms. A round-worm strength dosing of monthly Ivermectin will not only prevent new heartworm microfilaria from taking hold in your dog, it will also work to dramatically shorten the life of any existing adult worms in your dog. Bottom line: after 18 months of treatment, your dog will be heartworm-free at very little cost compared to other remedies.
Dosing Ivermectin Yourself
- Products like HeartGard are a prescription from your vet.
- You can buy Ivermectin at any Feed & Tack Store, Farm Supply or Online. It will be around $40 for a small bottle of “Sheep Drench” in 0.08% ß IMPORTANT as this is diluted sufficiently to give to dogs.
- One bottle will dose many dogs for probably a several years before the product expires. You do not need a large bottle.
- à If you buy any other % – a) don’t and b) calculations must be adjusted.
- If you are at all hesitant about weighing & dosing your dog yourself, stick with prescription products.
- Do NOT buy Horse Paste.
- If you are comfortable measuring dosages:
Up to 14 pounds: – given 0.05 ml or or 1 drop from an eye dropper, assuming 20 drops per ml)
15 to 29 pounds: 0.1 ml (two drops)
30 to 58 pounds: 0.2 ml (four drop)
59 to 88 pounds: 0.3 ml (6 drops)
89 to 117 pounds: 0.4 ml (8 drops)
118 to 147 pounds: 0.5 ml (10 drops)
Note: cc and ml are the same 
One dose is all that is needed.
Detox Ivermectin
Use a Detox protocol (Milk Thistle) 24 hours following administration of Ivermectin to support the liver. Ivermectin has a ½ life of 24 hours. So after 24 hours of administration, ½ the product will have been eliminated by the body. We can then feel confident that we’ve given the product time to eliminate the parasites, and then support the liver.