The plastic particles, usually smaller than 5mm in length, were found to be present in more than three quarters of pet food products, with "value ranges" containing higher percentages than more expensive brands.
Despite higher concentrations in dry food, wet food is actually responsible for a higher intake of microplastics, given the amount of food needed to meet daily requirements.
A call for new regulations
The team has called for new regulations to be introduced, which would require food manufacturers to test for microplastics in the same way they test for chemical contamination.
"Our results are a reminder that our pets are exposed to the same chemical pollutants as ourselves," University of Exeter professor Tamara Galloway explained.
Further research is now needed to find out whether ingredient quality, packaging types, or processing methods, are the main contributors to the problem."
Part of a wider issue
"Based on current information, the FSA considers it unlikely that the presence of microplastics in food or pet food would cause harm, though this will be kept under review as new evidence becomes available." clarified Dr James Cooper, from the Food Standards Agency.
While monitoring continues, UK Pet Food association is confident their members' products are safe for consumption. "Our members' pet food products comply with all applicable regulations and food safety standards, and pet owners can continue feeding commercially prepared pet food with confidence." they confirmed in a statement.