Ivermectin for Dogs Dosage Chart
Veterinary professionals are increasingly concerned about the number of pet owners searching for ivermectin dosage charts as though it’s a DIY tool. But here’s the raw truth: there’s no one-size-fits-all chart for ivermectin in dogs—because a safe dose depends on genetics, weight, indication, and formulation.
📌 Key Takeaways – Ivermectin Dosage for Dogs
| ❓ Question | ✅ Short Answer |
|---|---|
| Is there a universal dosage chart? | No. Each dose depends on weight, breed, and condition. |
| Can I use livestock ivermectin for dogs? | Absolutely not. Toxicity is likely, especially in small or sensitive dogs. |
| What’s the safe dose for heartworm prevention? | 6 mcg/kg once monthly, using FDA-approved products. |
| What’s the dose for mange treatment? | 200–600 mcg/kg, but only under strict veterinary supervision. |
| What breeds are at high risk of toxicity? | Collies, Aussies, Shelties, and other herding breeds. |
⚠️ There’s No Safe DIY Ivermectin Chart—Here’s Why
Dosage charts fail when they ignore the dog’s MDR1 gene mutation, formulation concentration, or intended use. Without those three details, a dose that’s safe for one dog could kill another.
| 🧩 Variable | 📈 Influence on Dosage | 🧠 Critical Risk Factor |
|---|---|---|
| 🐶 Breed Genetics | MDR1 mutation can reduce safe threshold by 20x | ✅ Requires genetic testing |
| ⚖️ Weight Accuracy | Dose is mcg/kg—not by guesswork | ❗ Precision down to decimals needed |
| 💊 Product Type | Livestock vs. canine versions differ 1,000-fold in concentration | 🚫 Never mix or substitute |
| 🧴 Route of Delivery | Oral, injection, topical each absorb differently | 🔄 Absorption affects toxicity onset |
🐕 FDA-Approved Ivermectin Dosages (Heartworm Prevention Only)
For heartworm prevention, the dosage is extremely low and only available in pre-measured chewables for precise safety.
| 💊 Product | 🐶 Dog Weight | 💉 Ivermectin per Dose | 📦 Color Code | 💡 Notes |
|---|---|---|---|---|
| Heartgard® Plus | 0–25 lbs | 68 mcg | Blue | Includes pyrantel for worms |
| 26–50 lbs | 136 mcg | Green | FDA-approved | |
| 51–100 lbs | 272 mcg | Brown | Use combo for >100 lbs |
✅ These are the only doses considered safe for all dogs, including MDR1 mutants. Never try to recreate this at home using bulk formulations.
🦠 Off-Label Ivermectin Use for Mange: Riskier, Not DIY-Friendly
Treating mange with ivermectin means diving into off-label territory, where the dosage spikes up to 100× the heartworm level—and so does the risk.
| 🐾 Condition | 💊 Dosage Range | 🧪 Frequency | 🛑 WARNING |
|---|---|---|---|
| Sarcoptic Mange | 200–300 mcg/kg | Once every 14 days x2–3 | Only with vet supervision |
| Demodectic Mange | 300–600 mcg/kg daily | Daily for weeks/months | MDR1 testing required first |
| Topical (Pour-on) | 500 mcg/kg | Days 1 and 15 | Off-label, cattle product—avoid at home |
🔥 Fact: A mange dose for one dog might be a fatal overdose for another of the same weight due to MDR1 mutation. That’s not guesswork—it’s genetics.
🧬 The Genetic Wildcard: MDR1 Sensitivity
This is where most ivermectin “chart” guides crash and burn: they don’t account for the MDR1 mutation that renders the drug fatally neurotoxic in some dogs—even at “safe” levels.
| 🧬 MDR1 Status | 🧠 Blood-Brain Barrier Status | 💀 Toxicity Threshold |
|---|---|---|
| Normal/Normal | Fully functional | ~2.5 mg/kg |
| Carrier (Normal/Mutant) | Partially compromised | ~0.6–1.0 mg/kg |
| Mutant/Mutant | Critically vulnerable | ~0.1 mg/kg |
Affected breeds include Collies, Australian Shepherds, Shelties, and their mixes. The only way to know? Genetic testing.
⚖️ Livestock Ivermectin = Russian Roulette 🎯
Here’s why you can’t just “scale down” a cattle or horse ivermectin product:
| 💉 Livestock Product | 🧪 Concentration | 🐕 Canine Equivalent Risk |
|---|---|---|
| Cattle Injection (1%) | 10,000 mcg/mL | 0.1 mL error = 1,000 mcg overdose |
| Horse Paste (1.87%) | 18,700 mcg/gram | Impossible to dose safely |
| Canine Heartworm Tablet | ~68–272 mcg/tablet | Safe & precise |
😱 Even a 0.05 mL overdose of livestock injectable can push an MDR1-positive dog into a seizure.
🧠 Ivermectin Overdose Symptoms: Know What to Watch For
Symptoms often show within hours. Immediate veterinary care is non-negotiable.
| 🚨 Toxicity Signs | ⏳ Onset Window | 📈 Severity Progression |
|---|---|---|
| Lethargy, drooling | 4–12 hrs | Early red flags |
| Vomiting, disorientation | 8–16 hrs | Moderate concern |
| Ataxia, blindness | 12–24 hrs | Severe neurological signs |
| Seizures, coma, death | 24+ hrs | Requires ICU-level care |
There’s no antidote—only intensive supportive therapy. The earlier you intervene, the better the outcome.
🧴 Ivermectin Isn’t One Drug—It’s Many Formulations
Different delivery methods absorb differently. Even a dose that’s safe orally may be toxic by injection or pour-on.
| 🧪 Formulation Type | 🚚 Absorption Rate | ⚠️ Risk Level |
|---|---|---|
| Oral Tablet | Predictable | 🟢 Safest route |
| Injection (SubQ) | Rapid systemic | 🔴 High risk without vet |
| Pour-On | Variable, risky | 🔴 Especially in small breeds |
📋 The Veterinarian Is the Chart
No downloadable table replaces the clinical decision-making of a vet. Here’s what they assess before prescribing:
| 🧠 Vet Decision Point | 🧪 Why It Matters |
|---|---|
| Confirmed Diagnosis | Mange? Worms? Allergy? |
| MDR1 Status | Risk of neurotoxicity |
| Weight + Age + Condition | Dosing precision |
| Drug Interactions | Other meds may affect safety |
| Safer Alternatives Available | Isoxazolines for mange, for example |
✅ Final Chart: Ivermectin Dosage Context Matrix
| 🐾 Use Case | 📉 Safe Dose Range | ⚠️ Key Risk Factors | 🧪 Route |
|---|---|---|---|
| Heartworm Prevention | 6 mcg/kg monthly | None at this dose—even for MDR1 | Oral chewable |
| Sarcoptic Mange | 200–300 mcg/kg | MDR1 gene, misdiagnosis | Oral/SubQ |
| Demodectic Mange | 300–600 mcg/kg | High cumulative toxicity | Oral daily |
| DIY Livestock Use | N/A | Dosage error, wrong ingredients | Unsafe |
FAQs
💬 Comment: Can I give ivermectin to my 12-lb Chihuahua using the horse paste if I calculate the dose correctly?
Absolutely not. Even a minuscule error in measuring a paste designed for 1,200-lb animals could deliver a dose 50× higher than safe. For small dogs, the margin of safety is virtually nonexistent—especially in breeds like Chihuahuas, where body mass is so low that even a 0.01 mL miscalculation can cause neurotoxicity. Moreover, pastes may contain inactive ingredients not tested in canines, which can lead to unpredictable absorption or reactions.
| 🐶 Small Dog Danger Chart |
|---|
| ❗ Weight: 12 lbs |
| 💊 Safe Dose: ~33 mcg |
| 🧪 Horse Paste: 18,700 mcg/g |
| 🚫 Unsafe Margin: >99.8% |
➡️ Use only FDA-approved chewables. They’re flavored, dosed per weight, and safe even for tiny dogs.
💬 Comment: My dog has mange. Can I give ivermectin every day if I start with a small amount?
Mange requires a vet-confirmed diagnosis and breed-specific treatment plan. Attempting a daily ivermectin regimen without guidance is high-risk, especially since mange protocols involve high-dose, long-term exposure—which can accumulate in the body and trigger toxicity, particularly in dogs with compromised liver metabolism or MDR1 mutations.
| 📅 Ivermectin Daily Use for Mange |
|---|
| ⚠️ Dosage Range: 0.3–0.6 mg/kg daily |
| ⏱️ Duration: 30–90+ days |
| 🧠 CNS Risk (MDR1+): Extreme |
| 🐾 Vet Supervision: Essential |
Important: Dogs often develop secondary infections with mange, requiring concurrent antibiotics and medicated baths—not just ivermectin alone.
💬 Comment: What if my dog licked ivermectin from manure or spilled livestock paste—what should I watch for?
This is a veterinary emergency. Livestock-treated manure contains ivermectin residues that can linger for weeks. A dog licking manure or residue can ingest enough to induce CNS depression, especially if the animal is small, geriatric, or genetically susceptible.
| 🐕 Ivermectin Exposure Signs |
|---|
| 😴 Early: Lethargy, drooling, disorientation |
| 👁️ Progressive: Dilated pupils, ataxia, confusion |
| 🚑 Severe: Blindness, seizures, coma |
Immediate action: Call a vet or poison control. If ingestion was within 4–6 hours, activated charcoal and emesis may be attempted. Do not delay.
💬 Comment: Why do herding breeds react differently to ivermectin?
The culprit is the MDR1 (ABCB1) gene mutation. In breeds like Collies, Aussies, and Shelties, this mutation disables the P-glycoprotein pump that normally keeps ivermectin out of the brain. As a result, doses that are harmless to most dogs cross the blood-brain barrier and cause neurotoxicity in these breeds.
| 🧬 Genetic Sensitivity Map |
|---|
| 🐶 Collies: Up to 70% affected |
| 🐶 Aussies: ~50% carry one copy |
| 🐶 Shelties & OES: High prevalence |
| 🧫 Testing: Available via cheek swab or blood sample |
Tip: Even carriers (one copy of the mutation) may show signs at higher doses. Testing costs less than one ER visit.
💬 Comment: How do I convert mg to mcg? The charts confuse me.
Great question. Precision in ivermectin dosing is absolutely critical—and confusion between mg and mcg is one of the leading causes of unintentional overdose.
| 🔍 Ivermectin Unit Conversion |
|---|
| ✅ 1 milligram (mg) = 1,000 micrograms (mcg) |
| 💊 0.3 mg/kg = 300 mcg/kg |
| ⚠️ 10 mg = 10,000 mcg (deadly if misused) |
Pro Tip: Always confirm units on the label. Veterinary drugs use mcg/kg, while livestock versions use mg/mL or % concentration—a key distinction.
💬 Comment: What happens if my dog misses a monthly heartworm dose?
Missing even one dose puts your dog at risk. Heartworm preventatives like ivermectin don’t kill adult worms, only larvae (L3–L4 stages). If larvae mature before the next dose, the infection can establish permanently.
| 🗓️ Dose Gap Timeline |
|---|
| 🟢 <30 Days: Likely still protected |
| 🟡 31–60 Days: Recheck + restart, consult vet |
| 🔴 >60 Days: Heartworm test required before resuming |
Year-round prevention is best. Contrary to myths, mosquitoes bite in winter in many climates.
💬 Comment: I saw ivermectin in a YouTube video treating COVID in dogs. Is that safe?
No. That claim is not only unsubstantiated, it’s medically reckless. Ivermectin has no approved antiviral use in canines. Its action targets glutamate-gated chloride channels—specific to parasites, not viruses. Attempting to use it for unrelated diseases in animals is a misuse that could cause irreversible harm.
| 🚫 Misuse Risk Breakdown |
|---|
| ⚠️ Unapproved use: Not safe for viral infections |
| 🔬 Mechanism: Parasite-specific channel interference |
| 🧠 Toxicity risk: Escalates with unnecessary dosing |
Never use off-label unless directed by a licensed veterinarian who understands pharmacokinetics and your dog’s individual health.
💬 Comment: “Why is my veterinarian so strict about only prescribing FDA-approved heartworm preventatives?”
Veterinarians are held to the highest standards of patient safety and legal compliance. FDA-approved heartworm preventatives are not only meticulously dosed for each weight category, but they also undergo rigorous safety and efficacy trials specific to dogs. These products account for pharmacological subtleties such as absorption rates, palatability, and metabolic stability. When owners request compounded, off-label, or livestock formulations, veterinarians are duty-bound to refuse—not out of caution alone, but to prevent tragic dosing errors or unknown adverse effects.
| 🏥 Why Vets Say “Only FDA-Approved” |
|---|
| ⚖️ Legal Obligation: Protects against malpractice and ensures compliance with veterinary law. |
| 🧬 Genetic Safety: Proper dosing for MDR1-sensitive breeds. |
| 🥇 Quality Control: Every batch is manufactured to strict standards. |
| 🦠 Contaminant-Free: No dangerous fillers or solvents. |
| 🐕🦺 Palatability & Compliance: Easier dosing means owners don’t skip doses. |
💬 Comment: “Is it safe to double the ivermectin dose if I miss a month of heartworm preventative?”
Never double up. Ivermectin doesn’t work by catching up—it eliminates specific heartworm larvae stages present at the time of administration. Doubling a missed dose doesn’t “erase” the gap and instead raises the risk of side effects, especially in MDR1-variant dogs. If you’ve missed a dose, schedule a heartworm test with your vet and follow their guidance for restarting the medication.
| 🚦 Missed Dose Protocol |
|---|
| ❌ Double Dosing: Increases toxicity risk. |
| 📆 Missed <30 days: Resume as normal, notify vet. |
| 🩺 Missed >30 days: Vet exam + antigen test needed. |
| ⏳ Prevention Only Works Forward: It’s not retroactive. |
💬 Comment: “Are there any visible signs of low-dose ivermectin sensitivity in my herding breed?”
Low-dose reactions are rare, but subtle warning signs exist. Even at preventative doses, dogs with two copies of the MDR1 mutation may exhibit mild neurological signs, especially if another stressor is present (illness, drug interactions, age). Always watch for new or unusual symptoms within hours of dosing.
| 👀 Signs to Watch in MDR1 Dogs |
|---|
| 💤 Unusual Lethargy |
| 😵 Disorientation/Stumbling |
| 👁️ Dilated Pupils or Glassy Eyes |
| 🐾 Shaking/Tremors |
If these occur, contact your vet. For most MDR1 dogs, low-dose heartworm products are considered safe—but vigilance is your ally.
💬 Comment: “What’s the risk if Ivermectin is given with other common medications?”
Ivermectin can interact with dozens of drugs—sometimes with dangerous consequences. Medications that inhibit P-glycoprotein (the pump protecting the brain from ivermectin) or those that depress the central nervous system can amplify ivermectin’s neurotoxic effects.
| 💊 Drug Interactions Table |
|---|
| 🚫 Ketoconazole/Spironolactone: Block P-gp, ↑ risk. |
| ⚠️ Acepromazine/Opioids: Enhance sedation. |
| 💢 Cyclosporine: Major risk for MDR1 dogs. |
| 🧬 Other Macrocyclic Lactones (milbemycin, moxidectin): Additive toxicity risk. |
Tell your vet about all medications and supplements, including flea/tick preventatives and herbal products.
💬 Comment: “Is topical ivermectin safer than oral or injectable forms?”
Not necessarily. While pour-on ivermectin has slower systemic absorption, dogs can ingest it by licking themselves or other treated animals—leading to unpredictable dosing. Additionally, absorption through the skin can vary wildly depending on the coat, skin health, and breed. Oral and injectable forms are more predictable and thus favored in veterinary protocols.
| 🧴 Topical Ivermectin Risks |
|---|
| 🐶 Self-Grooming: Ingests unknown amounts. |
| 👅 Licking Others: Shared toxicity risk in multi-dog homes. |
| 🩸 Broken Skin: Rapid, unsafe absorption. |
| ❓ No Veterinary Label: Formulated for livestock, not dogs. |
For any ivermectin use, oral prescription is safest under veterinary guidance.
💬 Comment: “Why can’t ivermectin treat fleas, ticks, or tapeworms in my dog?”
Ivermectin’s molecular target is highly specific to certain invertebrate neurotransmission systems (notably nematodes and some mites). Fleas, ticks, and tapeworms lack these particular glutamate-gated chloride channels, rendering ivermectin ineffective. Using it off-label for these parasites only exposes the dog to unnecessary risk without any benefit.
| 🚫 What Ivermectin Won’t Treat |
|---|
| 🐛 Tapeworms (Dipylidium, Taenia) |
| 🕷️ Ticks (Ixodidae) |
| 🐜 Fleas (Ctenocephalides) |
| 🦠 Flukes (Trematodes) |
There are targeted, safe treatments for these parasites. Consult your veterinarian for the right match.
💬 Comment: “Can dogs build up a tolerance to ivermectin over time?”
No physiological tolerance develops. Ivermectin doesn’t accumulate resistance within the dog’s body; instead, resistance can develop in parasite populations due to genetic mutations—not in the host. Long-term monthly dosing remains safe in healthy, properly selected dogs, provided dosages are correct and the product is FDA-approved.
| 📉 Tolerance & Resistance Facts |
|---|
| 🧬 No host tolerance |
| 🦠 Parasite resistance (rare in heartworm, more in livestock worms) |
| 🔄 Monthly dosing stays effective if used correctly |
Continuous veterinary monitoring is still essential for efficacy and safety.
💬 Comment: “If my dog vomits right after taking ivermectin, should I give another dose?”
Only under veterinary supervision. If vomiting occurs within 1–2 hours of ingestion, the dose may not have been fully absorbed. However, re-dosing is risky without certainty—especially in small dogs or breeds with MDR1 mutation, where repeating the full amount could lead to accidental overdose.
| 🤢 Post-Dose Vomiting Protocol |
|---|
| ⏱️ <2 Hours Post-Dose: Call vet before re-dosing. |
| 🔁 Do NOT repeat automatically. |
| 🧪 Watch for Signs: Lethargy, drooling, ataxia. |
| 👩⚕️ Vet May Prescribe: New dose or different formulation. |
Never estimate. Repeating without professional advice is dangerous—precision matters.
💬 Comment: “Can ivermectin cause long-term damage if the dog survives an overdose?”
Yes—especially neurological. Survivors of ivermectin toxicity may suffer from persistent ataxia, blindness, behavioral changes, or cognitive slowing. The drug’s lipophilic nature means it may linger in brain tissue, prolonging recovery. Some dogs regain full function; others may show subtle deficits for life.
| 🧠 Long-Term Effects of Ivermectin Toxicity |
|---|
| ⚡ Residual Ataxia: Uncoordinated movement. |
| 👁️ Vision Loss: Temporary or permanent. |
| 🧠 Memory/Behavior Shifts: Mood or learning deficits. |
| 💤 Fatigue/Weakness: Especially post-hospitalization. |
Early intervention gives the best chance at full recovery. Delayed care reduces neurological prognosis.
💬 Comment: “What’s the difference between ivermectin and moxidectin for dogs?”
They’re both macrocyclic lactones, but moxidectin is longer-acting and more lipophilic. This means it persists longer in tissues and is often used in extended-release preventatives (like ProHeart® or topical Advantage Multi®). Moxidectin may be safer at higher doses in some breeds, but like ivermectin, it still poses risk in MDR1-deficient dogs.
| ⚖️ Ivermectin vs. Moxidectin |
|---|
| 💊 Ivermectin: Shorter half-life; oral monthly. |
| ⏳ Moxidectin: Longer half-life; injectable/topical options. |
| 🧬 MDR1 Risk: Present with both, but some data shows moxidectin may cross BBB less readily. |
| 💉 Route Flexibility: Moxidectin offers injectable depot formulations. |
Veterinarians weigh both the dog’s genetics and the lifestyle risk factors when choosing between them.
💬 Comment: “Is ivermectin safe for pregnant or lactating dogs?”
Use with caution—and only under veterinary oversight. While some studies have shown no teratogenic effects at low doses, high-dose or off-label ivermectin use is not recommended in pregnant or nursing females due to the potential for embryotoxicity or transfer through milk.
| 🍼 Ivermectin & Reproductive Risk |
|---|
| 👶 Pregnant Bitches: Avoid off-label doses; use only if absolutely necessary. |
| 🐾 Lactation: Ivermectin is excreted in milk—risk to neonates. |
| 🧫 Studies: Show safety at labeled doses but lack large-scale trials. |
| ⚠️ Better Options: Often exist for parasite control in breeding females. |
Always disclose pregnancy or intent to breed when consulting a vet. Even “safe” meds can pose risk in this group.
💬 Comment: “Can ivermectin lose effectiveness if used for years?”
Not in the host—but yes, in parasites. Ivermectin itself doesn’t become less effective in the dog’s body, but heartworm microfilariae and intestinal parasites can develop resistance if exposed repeatedly without proper control programs. This is especially a concern in areas of confirmed heartworm resistance.
| 🦠 Ivermectin Resistance Realities |
|---|
| 🧬 No Host Tolerance: Same efficacy in body over time. |
| 🪱 Parasite Resistance: Can evolve, esp. in shelters or overused areas. |
| 🗺️ Endemic Zones: Southern U.S. regions now monitor for resistance. |
| 💡 Rotating Preventatives: Vet may switch drugs if resistance suspected. |
Sticking to proper monthly dosing, yearly testing, and vet oversight is key to avoiding therapeutic failure.
💬 Comment: “My senior dog is on heart meds—can he still take ivermectin?”
Yes—with caution. Many cardiac drugs (e.g., digoxin, enalapril, furosemide) don’t directly interact with ivermectin, but elderly dogs have slower metabolism, which may alter how they process the drug. More importantly, comorbidities like liver disease, kidney insufficiency, or low body fat can influence absorption and clearance.
| 🧓 Ivermectin in Senior Dogs |
|---|
| 💊 Check Drug Interactions: Especially CNS or diuretic drugs. |
| 🩺 Adjust Dose If Needed: Based on weight loss, bloodwork, or organ function. |
| 🧪 Regular Heartworm Tests: Older dogs more vulnerable to complications. |
| ⚠️ MDR1 Screening: Still relevant, even in older rescues or unknown ancestry. |
Veterinary guidance is non-negotiable in geriatric patients. Their physiology isn’t predictable like that of a young, healthy adult.
