Emergence of methicillin-resistantStaphylococcus pseudintermedius(MRSP) isolated from dogs with cutaneous and wound infections has significantly impacted veterinary medicine. This study aimed to isolateS. pseudintermediusfrom canine pyoderma and investigate the effects of ethanolic extracts ofPiper betle(PB),P. sarmentosum(PS), andP. nigrum(PN) on the bacterial growth and biofilm formation ofS. pseudintermediusand MRSP. Of the isolated 152 isolates, 53 were identified asS. pseudintermediususing polymerase chain reaction, and 10 isolates (6.58%) were identified as MRSP based on the presence ofmecA. Based on phenotype, 90% of MRSPs were multidrug-resistant. All MRSP had moderate (10%, 1/10) and strong (90%, 9/10) biofilm production ability. PB extracts were the most effective in inhibiting planktonic cells, and the minimum inhibitory concentration at which ≥50% of the isolates were inhibited (MIC50) was 256 µg/mL (256–1024 µg/mL) forS. pseudintermediusisolates and 512 µg/mL (256–1024 µg/mL) for MRSP isolates. The MIC90forS. pseudintermediusand MRSP was 512 µg/mL. In XTT assay, PB at 4× MIC showed an inhibition rate of 39.66–68.90% and 45.58–59.13% forS. pseudintermediusand MRSP, respectively, in inhibiting biofilm formation. For PB at 8× MIC, the inhibition rates forS. pseudintermediusand MRSP were 50.74–81.66% and 59.57–78.33%, respectively. Further, 18 compounds were identified in PB using gas chromatography–mass spectrometry, and hydroxychavicol (36.02%) was the major constituent. These results indicated that PB could inhibit bacteria growth of and biofilm formation byS. pseudintermediusand MRSP isolated from canine pyoderma in a concentration-dependent manner. Therefore, PB is a potential candidate for the treatment of MRSP infection and biofilm formation in veterinary medicine.