External Parasites in Rats and Mice – NAVLE Study Guide

External Parasites in Rats and Mice

Overview

External parasites (ectoparasites) are common in rats and mice, particularly in pet and laboratory populations. The most clinically significant ectoparasites include fur mites, tropical rat mites, and lice. While many infestations are subclinical in healthy animals, immunocompromised or genetically manipulated rodents may develop severe pruritus, dermatitis, anemia, and secondary bacterial infections. Understanding species-specific parasites, their clinical presentations, zoonotic potential, and appropriate diagnostic and treatment strategies is essential for the NAVLE and clinical veterinary practice.

Species-Specific External Parasites

Key Point: Fur mites are the most common external parasites in both rats and mice. Tropical rat mites are the most dangerous due to their zoonotic potential and blood-feeding behavior. Lice are species-specific and will not cross between rats and mice.

Fur Mites

Etiology and Transmission

Fur mites are the most common external parasites of pet and laboratory rats and mice. In mice, the three most common species are Myobia musculi, Myocoptes musculinus, and Radfordia affinis. In rats, Radfordia ensifera is the primary fur mite species. These mites feed on skin secretions and interstitial fluid but are NOT blood-suckers. Transmission occurs primarily through direct contact between animals. These mites are often endemic in rodent populations with no visible symptoms in healthy, immunocompetent animals.