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.