Larval survival of Aelurostrongylus abstrusus lungworm in cat litters

The dehydrating power of cat litters may reduce the vitality of first-stage larvae (L1s) of feline lungworms, limiting copromicroscopical diagnosis. This study assessed the effect of the most commonly used cat litters on Aelurostrongylus abstrusus L1 survival.

Four types of cat litters were used: clumpling clay (group A); non-clumpling clay (group B); silica crystals (group C); and biodegradable (group D). A control group without litter (group E) was also included. On study day 0 (T₀), L1s were obtained by the Baermann-Wetzel technique from the faeces of a naturally infected cat and ~100 larvae were injected in each of the 20 lungworm larvae-free faecal samples (~2 g each). Thereafter, four faecal samples per group were transferred into plastic cups containing the four different types of cat litters, or into empty cups (group E). The survival of L1s was assessed in each group after 3 (T₃), 6 (T₆), 12 (T₁₂) and 24 (T₂₄) h, using the Baermann-Wetzel technique.

A decreasing trend of L1 survival was observed in all groups, with highest significant values at T₀ compared with T₃, T₆, T₁₂ and T₂₄ (P <0.001). However, at T₂₄, a significantly higher number (P <0.05) of L1s was extracted from faeces of the control group compared with the four groups with cat litters.

This study demonstrates how the survival of A abstrusus L1s, and therefore diagnosis, may be negatively influenced by the litter. The effect is time dependent, with a reduction in the number of vital larvae according to the type of litter, over time. False-negative results may be obtained, especially in cases of low parasitic load or when the sample is collected many hours after the emission.