Vesicles on the teat skin of a dairy cow

Time and location: October 2019, Malanda Queensland.

Case definition: Fluid-filled vesicles on cloven-hoofed animal.

Gross findings: An 11 year-old dairy cow with fluid-filled vesicles on the rear teats (about 5mm wide) noted by the owner at the afternoon milking. This cow has no oral or foot lesions. Only one cow in a herd of 300 affected. The differential diagnoses were: Vesicular Diseases (FMD, Vesicular Stomatitis etc), Bovine Papular Stomatitis, Poxvirus, Staph impetigo, Bovine Herpesvirus, and BVD. Samples submitted included:

• bloods – EDTA, heparin and clotted
• fluid aspirate from intact vesicles
• fresh lesion for PCR (lid of vesicle)
• Amies Media swab of discharge for microbial culture and sensitivity
• fixed tissue for histopathology (entire lesions / excisional biopsy).

Laboratory findings: All major EADs were ruled out with:

• AAHL testing negative for FMD serotypes, Vesicular Stomatitis serotypes and BHV-4
• State vet lab (BSL) testing negative for BHV-1, BHV-2, BVD and FMD PCR.

Bacterial culture (for Staph) was not done as the Amies swab was used for the FMD PCR, and the labs do not have a molecular test that they deem suitable for poxvirus.

Animal / management / environment risk factors: The lesions were self-resolving.