Which virus in rats may increase anesthesia-related mortality but may be clinically silent?

• A. Sendai virus
• B. Lymphocytic choriomeningitis virus
• C. Parvovirus
• D. Sialodacryoadenitis virus

Answer: (D)

The situation tested is how some rat infections can be hidden in the animal yet become dangerous under anesthesia. Sialodacryoadenitis virus is a rat coronavirus that predominantly affects the salivary and lacrimal glands and can cause ocular and nasal signs, but many infections are subclinical or very mild. Under anesthesia, however, any underlying airway or respiratory tract involvement can be amplified, leading to bronchitis or pneumonitis and, in some cases, anesthesia-related mortality. Because an animal may look healthy at baseline and show little to no clinical signs, it’s easy to miss the risk unless routine health monitoring and colony management are in place. The other viruses listed are typically associated with more evident clinical disease or have less clearly documented links to anesthesia-related mortality in clinically silent infections.