Swinepox is an acute skin disease of pigs caused by the swinepox virus (SPV) and was recognized for the first time in the USA in 1929. Although its incidence is low and its economic impact may be minimal, the disease still exists in US swine populations. Various methods have been utilized to detect SPV in clinical specimens, ranging from conventional methods like electron microscopy and virus isolation to molecular assays such as polymerase chain reaction (PCR) and sequencing. Among these methods, PCR testing has been most commonly employed to detect the virus. Yet, any of the published PCR tests have not been evaluated for their diagnostic performance on SPV-suspect cases in US swine populations. The following study was conducted to develop a PCR assay based on sequences of SPV of US origin and compare its diagnostic performance to the other published PCR tests, including a pan-poxvirus PCR as the reference test. A primer pair (forward: 5’-CCCATTCATCTAGCTCTTCG-3’; reverse: 5’-GTATAGCATATCACCATGGT-3’) was designed and selected for specific detection of SPV through bioinformatics analysis of various poxviruses, evaluation of their suitability for melting temperature, GC content, potential dimer formation, and secondary structure, and PCR optimization process. The newly developed PCR assay showed no cross-reactivity with many other common swine viral pathogens. Diagnostically, the new PCR assay showed 87.6% test agreement with the pan-poxvirus PCR, whereas the other published PCR tests for SPV showed 62.5% test agreement. While the pan-poxvirus PCR requires sequencing PCR products to identify virus species, the new PCR assay does not require sequencing but performed better than the other SPV-specific PCR tests. Therefore, the newly developed PCR assay can be a laboratory tool for rapid and specific detection of SPV in suspect cases in US swine, leading to a conclusive diagnosis of SPV-associated dermatitis.