May 2020

Rats!

A fecal sample from a 2 year-old male rat rescued from a hoarding situation, was submitted for gastrointestinal parasites evaluation. The rat did not show any symptoms at submittal but the feces was soft in consistency.

For fecal analysis, a centrifugal fecal flotation with Sheather’s sugar solution (specific gravity, 1.26) was performed, and a low number of eggs were observed.

What's your diagnosis?

Trichosomoides crassicauda or bladder threadworm, is a parasite of the urinary bladder of rats. The female is 10–19 mm long; the male measures 1.5–3.5 mm.  A curious fact about this parasite is that the male lives inside the uterus of its mate (hyperparasite).  

The medium‐sized egg is lemon‐shaped with transparent polar plugs and measures about 60–70 by 30–36 μm. The shell is thick and brown, and contains either a morula or an L1 larva. 
 
How did the rat become infected? Usually from mother rats to their offspring before weaning. 

Is it pathogenic? The presence of the worms can cause nodules in the bladder wall.
 
How do you treat it? In laboratory animals successful treatment has been achieved with Ivermectin subcutaneously at 0.2 mg/kg or orally at 3mg/kg.