Langman V, Ellifrit N, Sime D, Rowe M, Hogue A. (2015). Testing Refrigerator Trucks for the Emergency Evacuation of Companion Animals. Journal of Applied Animal Welfare Science, 18:4, 398-403.
Research question: When hurricanes require the emergency evacuation of dogs and cats from coastal areas, can sealed refrigerator trucks be used as safe transport for the crated animals? And how dramatically will carbon dioxide (CO2) levels increase and oxygen (O2) levels decrease (and reach potentially lethal conditions) as the animals breathe?
Sample: A total of 122 companion animals (total weight = 2,751 lbs.) housed in individual crates were loaded into a 53-ft. refrigerator truck. The animals, which came from surrounding animal shelters, consisted of 90 dogs (average weight = 28 lbs.) and 33 cats (average weight = 6.4 lbs.).
Methodology: The animals were loaded into an airtight refrigeration truck at an animal shelter in Baton Rouge, La. for an emergency evacuation. Researchers measured levels of CO2 and O2 before and immediately after the doors shut—and every five minutes thereafter. When the doors were shut, O2 and CO2 were at normal atmospheric levels: 21 percent O2 and 0 percent CO2. To ensure animal safety and comfort, the doors were opened when CO2 levels reached 1.5 percent or when O2 levels dropped to 19.5 percent. There is no mention of the truck’s interior temperature.
Findings: Researchers ended the experiment after 165 minutes, once CO2 and O2 levels were 1.5 percent and 19.5 percent, respectively. Once the doors opened, it took 30 minutes to completely rid the compartment of CO2. As authors suggest, the CO2 levels had a much higher-than-predicted increase, and O2 had a higher-than-predicted decrease. A team of five veterinarians observed each animal and there were no reports of adverse effects on the animals, but because the reported O2 levels can cause hypoxia and the reported CO2 levels can cause hypercapnia, researchers conclude that extending the transport time can cause asphyxia or suffocation, and potentially mortalities. For this study, researchers recommended a two-hour stop frequency, but variables in animal count, weight and truck specifications will require more frequent stops.
Limitations: These findings reflect careful adherence to a very specific set of parameters, and if any one of those parameters had changed, the potential for adverse effects to the animals could have risen substantially. As such, limitations include: 1) potential challenges of complying with the required door opening frequencies, especially during heavy evacuation traffic; 2) changing numbers of animals in each load from this study’s sample of 122 dogs and cats; 3) changing weight of animals in each load from this study’s sample of 2,751 lbs.; 4) changing the size of the sealed compartment from this study’s 53-foot truck; 5) varying sizes of air-circulating units. And less importantly but still a consideration, researchers in this study assumed that problems associated with comingling between dogs/cats and animals with underlying health issues were kept to a minimum—meaning those issues could present challenges with future applications of this research.
Summary by Bana Jobe