Abstract
Background
Dogs are regularly transported or housed in vehicles, with guidelines for housing dogs suggesting that the ambient temperature should be maintained between 15 – 24 °C. Veterinary drugs are routinely stored and carried in vehicles providing ambulatory veterinary care. Non-refrigerated medications typically require storage between 8 – 25 °C. This study aimed to investigate the potential for thermal stress associated with vehicular storage and transportation of drugs and dogs in a temperate climate such as the United Kingdom.
Methods
The study used data loggers to continuously record internal temperatures of four vehicles at 15-minute intervals over a two-year period, to investigate the effect of seasonality and time of day on internal car temperature.
Results
Internal car temperature ranged from -7.4 °C to 54.5 °C during the study period. Temperatures fell below 8 °C in every month except June and July. Internal car temperature exceeded typical drug storage recommendations (> 25°C) during every month, and exceeded the canine thermo-neutral zone (> 35°C) from April to September. Peak temperatures occurred between 14:00 and 17:00 hours.
Conclusion
The results demonstrate the year-round potential for thermal stress of both dogs and drugs left in cars. Public awareness campaigns highlighting the risks of leaving dogs in hot cars are typically launched in late spring, but should consider launching earlier in light of these findings. Veterinary surgeons transporting drugs should take measures to ensure drugs are stored within the manufacturer’s temperature range year-round. This will limit the potential for drug degradation and decreased efficacy.

Key words: Car temperature, drug storage, dog transport, thermal stress