A Comparison of the Number of Bacterial CFUs Found on Cats' Paws

This experiment was designed to determine if the type of cat litter used would change the amount of bacteria found on cats’ paws.  It was hypothesized that scoopable cat litter would transfer more bacterial contamination to the subjects’ paws because only the fecal material and urine are taken out, and not all of the litter is thrown away.  This could allow for a large amount of bacteria to remain in the litter box that could contaminate the subjects’ paws.  Three types of cat litter were tested in this experiment; clay, scoopable, and recycled newspaper.  The cats’ paws were cleaned before they were placed with the correct cat litter and left with that litter for 36 hours.  The samples were taken by placing the cats’ right front paw pads on both blood and MacConkey agar plates.  The samples were diluted with 200µl of sterile water and then spread using the spread plate method.  The plates were incubated at 38.3°C (feline body temperature) in a bacterial culture incubator for 48 hours.  The CFUs (colony forming units) were counted and recorded every 24 hours.  The type of litter did not significantly alter the amount of bacterial contamination found on the cats’ paws.  However, recycled newspaper had the higher total number, with 1619 CFUs.  The scoopable had a total CFU count of 1342, and the clay had 1005 total CFU.  This research has importance for cat owners, especially those with compromised immune systems, when choosing a cat litter that best suits their needs.