The mg vs mL Problem in Common Bird Parasite Treatments
As avian veterinarians, one of the most common medication errors we see is significant overdosing of macrocyclic lactone drugs such as ivermectin, moxidectin and eprinomectin. In most cases, this is not intentional misuse, it is the result of unit confusion, product concentration differences, and misinformation copied endlessly online.
In this article, we will break down:
- Why these drugs are so commonly overdosed
- The critical difference between mg and mL
- How product concentration changes everything
- Why birds require much lower doses than most people realise
- Correct, veterinarian-backed dose ranges for commonly used products
This is not about blame, it is about preventing avoidable toxicity in birds.
The Core Problem: mg vs mL
This is where most internet dosing goes wrong.
mg (milligrams)
- A measure of drug amount (the actual active ingredient)
- This is what dose rates are based on medically
mL (millilitres)
- A measure of liquid volume
- The amount of drug in each mL depends entirely on the product concentration
mg tells you how much drug is needed.
mL tells you how much liquid you draw up to reach that dose.
When people skip the mg step and dose directly in mL without accounting for concentration, overdosing happens, often by a factor of 5–20×.
Why Birds Are Especially at Risk
Birds are not small mammals.
Key differences include:
- Faster metabolism but narrower safety margins
- Different liver enzyme pathways
- Higher sensitivity to neurotoxic effects of macrocyclic lactones
- Very small body weights, where tiny errors matter
A dosing error of 0.05 mL might seem insignificant, but for a finch, budgie or pigeon, it can be catastrophic.
The Concentration Trap
Many products on the market were never designed for birds.
Common livestock formulations include:
- Ivermectin 1% = 10 mg/mL
- Moxidectin 0.1% = 1 mg/mL
- Eprinomectin 0.5% = 5 mg/mL
If someone reads “dose at 0.2 mg/kg” but mistakenly gives 0.2 mL/kg, the bird receives:
- Ivermectin: 10× overdose
- Eprinomectin: 25× overdose
And this is exactly what we see repeated online.
Why the Internet Keeps Getting This Wrong
- Old forum posts copied without context
- Mammal dosing incorrectly scaled down
- Confusion between topical vs oral dosing
- People repeating what “worked once” without understanding margins
- No adjustment for formulation strength
Unfortunately, birds that survive overdosing often still suffer neurological or organ damage that goes unrecognised.
Why “More” Is Not Better
With these drugs:
- Higher doses do not improve efficacy
- Parasite kill is receptor-based, not dose-linear
- Toxicity increases rapidly beyond the therapeutic window
Signs of overdose can include:
- Ataxia (loss of coordination)
- Tremors
- Lethargy
- Blindness
- Seizures
- Sudden death
Common Products Used and Dose Rates
-
Cydectin Oral Drench (oral or topical)
Active: Moxidectin
Dose rate: 0.2 –0.4 mg/kg
mg/ml in product: 1mg/ml
Administeration volume per kg: 0.2 - 0.4ml/kg
-
Cydectin Pour On (topical)
Active: Moxidectin
Dose rate: 0.2 –0.4 mg/kg
mg/ml in product: 5mg/ml
Administeration volume per kg: 0.04 - 0.08ml/kg
-
Eprinex (topical)
Active: Eprinomectin
Dose rate: 0.2 –0.4 mg/kg
mg/ml in product: 5mg/ml
Administeration volume per kg: 0.04 - 0.08ml/kg
-
Ivomec 1% (oral or topical)
Active: Ivermectin
Dose rate: 0.2 –0.4 mg/kg
mg/ml in product: 10mg/ml
Administeration volume per kg: 0.02 - 0.04ml/kg
-
Moxidectin Pour On (topical)
Active: Moxidectin
Dose rate: 0.2 –0.4 mg/kg
mg/ml in product: 5mg/ml
Administeration volume per kg: 0.04 - 0.08ml/kg
Why “More” Is Not Better
With these drugs:
- Higher doses do not improve efficacy
- Parasite kill is receptor-based, not dose-linear
- Toxicity increases rapidly beyond the therapeutic window
Signs of overdose can include:
- Ataxia (loss of coordination)
- Tremors
- Lethargy
- Blindness
- Seizures
- Sudden death
The Avian Empire Approach
At Avian Empire, we:
- Calculate doses by mg/kg first — always
- Use bird-appropriate dilutions
- Avoid long-acting products where not indicated
- Provide clear, written dosing instructions
- Prefer precision over convenience
If you are ever unsure, do not guess. Ask.
