Imidocarb
Imidocarb dipropionate
Also known as: Imizol · Imidocarb dipropionate · Imidocarb hydrochloride · 4A65 · Imidocarbum
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Babesiosis | 6.6 mg/kg | IM or SC | repeat dose in 2 weeks | — | 🌎 NA |
| Babesiosis | 5-6.6 mg/kg | IM or SC | repeat in 14 days | — | 🌎 NA |
| Ehrlichiosis (Severe cases) | 5 mg/kg | SC | single injection or two injections 15 days apart | — | 🌎 NA |
| Hepatozoonosis (H. canis) | 5 mg/kg | IM or SC | every 14 days | until parasitemia clears | 🌎 NA |
| Treatment of Babesia canis infection | 6.6 mg/kg | IM/SC | once, repeated in 2-3 weeks | 2 doses total | 🌍 EU |
- Babesiosis: Alternatively, 7.5 mg/kg IM or SC once. A single dose of 6 mg/kg the day following a dose of diminazene at 3.5 mg/kg has also been shown to clear the infection.
- Ehrlichiosis (Severe cases): Given with doxycycline at 10 mg/kg/day for 28 days. Note: Imidocarb alone is not effective in clearing E. canis.
- Hepatozoonosis (H. canis): Usually 1-2 injections are sufficient.
- Treatment of Babesia canis infection: Dose based on imidocarb dipropionate (121.15 mg/ml). Premedication with atropine (0.05 mg/kg) to minimize side effects is highly recommended.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Cytauxzoon felis | 3-4 mg/kg | IM | repeated 7 days after initial dose | — | 🌎 NA |
| Cytauxzoon felis | 5 mg/kg | IM | once and then 14 days later | — | 🌎 NA |
| Feline hemoplasmosis (Mycoplasma haemofelis, M. haemominutum) | 5 mg/kg | IM, SC | every 14 days | until able to maintain a normal PCV | 🌎 NA |
| Feline clinical ehrlichiosis or anaplasmosis | 5 mg/kg | IM | every 14 days | for at least 2-4 treatments | 🌎 NA |
| Treatment of large babesial species infection | 2.5 mg/kg | IM | once | 1 dose | 🌍 EU |
- Cytauxzoon felis: Efficacy not proven. Cholinergic effects can be mitigated by pre-treating with atropine. Must also give supportive therapy (IV fluids, prophylactic heparin, nutritional/nursing care, analgesia, and potentially transfusion).
- Feline hemoplasmosis (Mycoplasma haemofelis, M. haemominutum): Alternative for cats intolerant of doxycycline.
- Feline clinical ehrlichiosis or anaplasmosis: Alternative to doxycycline.
- Treatment of large babesial species infection: Dose based on imidocarb dipropionate. Can improve clinical signs. Alternative agents are preferable for smaller species (e.g., B. felis).
Horses
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Equine piroplasmosis (Babesia caballi; Babesia equi) | 2.2 mg/kg | IM | once | — | 🌎 NA |
| Equine piroplasmosis (Babesia caballi) | 2 mg/kg | IM | once a day | for 2 days | 🌎 NA |
| Equine piroplasmosis (Babesia equi) | 4 mg/kg | IM | at 72 hour intervals | for 4 doses | 🌎 NA |
- Equine piroplasmosis (Babesia caballi; Babesia equi): Will generally allow clinical signs to subside.
- Equine piroplasmosis (Babesia caballi): To eliminate B. caballi.
- Equine piroplasmosis (Babesia equi): B. equi is more difficult to eliminate.
Sheep
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Babesiosis | 1.2 mg/kg | IM | repeat in 10-14 days | — | 🌎 NA |
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Imidocarb dipropionate is a diamidine antiprotozoal agent primarily used in veterinary medicine to treat tick-borne protozoal infections.
Key Clinical Applications:
- Babesiosis: Highly effective against Babesia canis in dogs, as well as Babesia species in horses and sheep.
- Cytauxzoonosis: Used in cats for Cytauxzoon felis infections, often as part of a comprehensive treatment protocol.
- Other Uses: Sometimes utilized as an alternative or adjunct treatment for Ehrlichia canis, Hepatozoon canis, and feline hemotropic mycoplasmas (e.g., Mycoplasma haemofelis).
Clinical Pearl: While highly effective for B. canis, it is generally less effective against B. gibsoni. It does not clear the encysted stage of Hepatozoon americanum.
Mechanism of action
Imidocarb acts by directly targeting the nucleic acids of susceptible protozoal organisms.
- It binds to and intercalates with DNA → causing the double helix to unwind and denature.
- This structural damage → inhibits cellular repair and replication → leading to parasite death.
- Mechanistic Note: As a diamidine derivative, it may also interfere with polyamine synthesis and function, further disrupting the parasite's metabolic pathways.
Safety & warnings
Contraindications
- Intravenous (IV) administration
- Patients exposed to cholinesterase-inhibiting drugs
- Patients exposed to pesticides or certain chemicals
Adverse effects
- Pain and inflammation at the injection site (rarely ulceration)
- Salivation (drooling)
- Nasal drip/discharge
- Vomiting (usually brief)
- Panting
- Diarrhea
- Restlessness
- Lacrimation and sweating (horses)
- Severe renal tubular or hepatic necrosis (rare)
- Injection site inflammation (mild to severe, potential ulceration)
- Anaphylactoid reactions (reported in cattle)
Precautions
Important Warnings
- Do NOT administer intravenously (IV).
- Premedication: In cats, puppies, and debilitated dogs, pretreatment with an antimuscarinic agent (e.g., atropine or glycopyrrolate) is strongly advised to mitigate cholinergic side effects.
- Organ Dysfunction: Use with caution in patients with impaired lung, hepatic, or renal function; weigh risks versus benefits.
- Species Sensitivities: Donkeys appear to be particularly sensitive to the toxic effects of imidocarb.
- Reproductive Safety: Safety in puppies, pregnant, lactating, or breeding animals has not been established.
Drug interactions
Increased risk of severe cholinergic toxicity; concurrent use is contraindicated.
May exacerbate cholinergic adverse effects and toxicity.
Increased risk of severe cholinergic toxicity
Monitoring
- Clinical efficacy (resolution of parasitemia and clinical signs)
- Adverse effect profile (cholinergic signs, injection site reactions)
- Creatine kinase (CK) levels (may be significantly increased post-IM injection)
- Liver and kidney function (especially in cases of suspected overdose or pre-existing disease)
- Resolution of clinical signs of babesiosis (fever, anemia, lethargy)
- Blood smears or PCR to confirm parasite clearance
- Injection site for signs of inflammation, necrosis, or ulceration
- Immediate post-injection monitoring for cholinergic crisis
Pharmacokinetics
Half-life
Absorption
No specific information available in the monograph.
Distribution
No specific information available in the monograph.
Metabolism
No specific information available in the monograph.
Elimination
No specific information available in the monograph.
Overdose
Acute Toxicity & Overdose Signs:
- Dogs: At 1.5X the labeled dose (9.9 mg/kg), dogs exhibited signs of liver injury (mildly elevated liver enzymes), pain/swelling at the injection site, and vomiting.
- General Overdose/Chronic Toxicity: Presents primarily with severe cholinergic signs (vomiting, weakness, lethargy, excessive salivation) or adverse changes in liver, kidney, lung, or intestinal function.
- Horses: The reported LD-50 is 16 mg/kg.
Treatment:
- Atropine or other antimuscarinics may be highly useful to treat the cholinergic signs associated with imidocarb toxicity.
- Provide symptomatic and supportive care for organ dysfunction.
Available products
Formulations
- Injection (120 mg/mL)
- Injectable solution: 85 mg/ml imidocarb base (equivalent to 121.15 mg/ml imidocarb dipropionate)
Veterinary
- Imidocarb Dipropinate for IM or SC Injection: 120 mg/mL in 10 mL multi-dose vials (Imizol®)
- Imizol 85 mg/ml solution for injection (121.15 mg/ml imidocarb dipropionate)
Regulatory status
Withdrawal times: cattle meat 213 days · cattle milk 21 days
Licensed primarily for cattle; used off-label in dogs and cats under the cascade.
Withdrawal times: cattle meat 213 days · cattle milk 21 days
Licensed primarily for cattle; used off-label in dogs and cats under the cascade.
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store between 2°-25°C (36°-77°F) and protect from light.
Client information
Important: This medication is administered exclusively by your veterinarian via injection.
- Purpose: Imidocarb is used to treat serious, tick-borne blood parasite infections such as Babesia or Cytauxzoon.
- What to Expect: The injection can be quite painful. Shortly after receiving the medication, your pet may experience drooling, a runny nose, panting, or brief episodes of vomiting. These are known, common reactions and usually pass quickly.
- Precautions: Please inform your veterinarian immediately if your pet has recently been exposed to any flea/tick dips, pesticides, or is taking other medications (especially those affecting the nervous system), as these can increase the risk of severe side effects.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.