The veterinarian diagnoses most worm infections by identifying the characteristic eggs of the different species in the faeces. However, there are several exceptions. Filaroides osleri are found in the sputum, while the eggs of the Capillaria plica are passed in the urine. Dipetalonema and Dirofilaria microfilariae are found in the blood. Strongyloides stercoralis eggs usually hatch in the intestines; therefore, first stage larvae are found in the faeces of an infected dog.

The major types of eggs which are present in canine faeces include:

Strongyle-type eggs

The hookworms, Ancylostoma, and Uncinaria, lay "strongyle type" eggs which are oval with smooth thin shells. When laid, the eggs have already begun to develop and are called "segmented" because the inner mass has split into a group of cells (fig 1).

Lungworm and Whipworm

Capillaria, the lungworm, and Trichuris vulpis, the whipworm, lay barrel shaped eggs with a transparent plug at each end. The plugs of the Capillaria egg are often asymmetrically placed (fig 2a lungworm, fig 2b whipworm).

Spirurids

Physaloptera and Spirocerca lupi eggs are small and oblong. By the time the egg is passed in the faeces, it already contains a nematode larvae (fig 3).

Toxascaris

Toxascaris leonina eggs are slightly oval with smooth, thick shells (fig 4).

Toxocara

Toxocara canis, the common canine roundworm, lays round eggs with thick, pitted shells (fig 5).

Cestodes

• Common Tapeworms
  Dipylidium caninum, known as the common tapeworm, sheds elongated segments called proglottids that resemble rice grains. Each proglottid contains packets of eggs (fig 6).
• Hydatid Tapeworm and Taenia
  Echinococcus granulosus and Taenia species are passed in the faeces as eggs that are round with thick striated coats. Each egg contains a larvae with six hooks. If ingested by human beings, Echinnoccus can cause serious damage. Therefore, faeces must be handled with caution (fig 7).

Control

Summary