1. Contact your veterinarian immediately for further advice. Depending on the dose your pet has ingested, you may be required to take your pet to your veterinarian for decontamination. Bring the medication your pet has ingested, with its package insert and/or label for confirmation of the specific drug involved and calculation of dose ingested to give the vet an idea of the severity of toxicity and treatment plan.
  2. In severe cases your pet may require hospitalisation for a few days. Treatment may involve close monitoring of blood pressure and aggressive intravenous fluid therapy to maintain it within the normal range. Monitoring of urine output and kidney parameters and electrolyte levels in blood is also advised.
  3. If your pet is stable or had a mild overdose, veterinary care may involve inducing vomiting if ingestion occurred within the hour and/or activated charcoal can be given to absorb any more circulating drugs in the system. If deemed necessary, a gastric lavage may also be performed to evacuate the contents in your pet’s stomach to get rid of any more drugs in its system.


Angiotensin converting enzyme inhibitor; various brand names



  • ACE inhibitors should be dosed judiciously in patients with heart or kidney disease, especially when used with other medications, as they lower blood pressure, which can be life threatening if severe. High doses of ACE inhibitors can also cause kidney failure. Severity of toxicity is dose dependent.
  • ACE inhibitors cause changes in electrolyte and fluid balances and have some other minor effects on other organs or body systems as well.
  • Some ACE inhibitors will cross the placenta and may harm foetuses.


  • Signs associated with low blood pressure:
  • Lethargy/Weakness
  • Dullness/Disorientation
  • Inappetance
  • “Shock” – increased heart rate (tachycardia), increased respiratory rate (tachypnoea)
  • Excessive thirst (polydipsia)
  • Excessive urination (polyuria)
  • Inability to produce urine (anuria)
  • Collapse
  • Seizures
  • Death
  • Adverse effects: Rare but more associated with Captopril Gastrointestinal upset – vomiting, diarrhoea, inappetence


The main effect of ACE inhibitors is to lower blood pressure by causing dilation of blood vessels, which can be life threatening if severe.

Some pets may also show gastrointestinal signs related to an allergic type reaction to this drug, which may not be related to dose.


Livshits A (2012) ACE Inhibitor Overdoses. Toxtidbits. Maryland Poison Center monthly update. January issue

Plumb DC (2011) Plumb’s Veterinary Drug Handbook 7th Edn. Wiley-Blackwell, Iowa, USA.

BSAVA (2011) BSAVA Small Animal Formulary 7th Edn. Ramsey I (ed.) Gloucester: BSAVA

Varon JV & Duncan SR (1991) Naloxone reversal of hypotension due to captopril overdose. Annals of Emergency Medicine 20(10): 1125-1127

Harewood WJ, Phippard AF, Duggin GG, Horvath JS & Tiller DJ (1994) Fetotoxicity of angiotensin-converting enzyme inhibition in primate pregnancy: A prospective, placebo-controlled study in baboons. American Journal of Obstetrics Gynecology 171(3): 633-642