Antifreeze, ethylene glycol, is notoriously dangerous to cats but can also cause severe toxicity in dogs, usually during the winter months.
Common sources of ethylene glycol include automotive antifreeze, radiator coolant, which typically contains 95% ethylene glycol, windshield deicing agents, motor oils, hydraulic brake fluid, developing solutions for photography, paints and solvents. Just a small quantity can result in severe renal toxicity in dogs.
Clinical signs can be categorised into 3 stages:
Stage 1: Clinical effects occur between 30 minutes and 12 hours. Common signs include in-coordination, salivation, vomiting, seizures, drinking and urinating more than normal.
Stage 2: This occurs within 12-24 hours post exposure, and cardiopulmonary signs such as difficulty breathing, increased heart rate, altered blood pressure, and circulatory shock may develop.
Stage 3: This final stage occurs 36-72 hours post ingestion in dogs. During this stage, severe kidney impairment is occurring. Late signs of inappetence, lethargy, bad breath, coma, depression, vomiting and seizures may be seen. Low blood calcium can cause muscle spasms.
If antifreeze has been ingested, the urine may fluoresce from the fluorescent dye in the product, when examined under ultraviolet light. Flourescien is present in many commercial antifreeze products which can be a good indicator but is not always reliable.
Dogs are more likely to be observed ingesting antifreeze and/or noticed to be unwell, unlike cats who tend to disappear overnight. Dogs are therefore more likely to receive prompt treatment, which is vital to secure a good outcome.
Treatment for ethylene glycol poisoning requires aggressive intervention and administration of the antidote, where possible.
Ethanol is the antidote and must be given intravenously. The sooner the antidotal therapy is started after ingestion, the better the outcome.