Nematodes 1

Toxocara canis; characterized by a thick, rough, pitted shell.

Toxocara cati; same rough, thick, pitted shell but slightly smaller than Toxocara canis

Toxascaris leonina; has a lighter appearance in the embryo and a smooth outer shell with a roughened inner layer; ascarid of dog and cat

Ascarid Roundworm (Arrowhead)

Division of the zygote of a Toxocara egg. Left: Cell; Right: Morula

Larvae of Toxocara can live within the egg for many months

vermi-form embryo, larvae developing within the eggs of Toxascaris leonina

Toxocara canis egg that has ruptured spilling out its contents

• Left: Toxascaris leonina;
• Right: Toxocara canis; egg is brownish in color with a pitted shell

Massive Ascariasis in a young dog, this will often lead to intussusceptions

Eggs of Toxocara cati the ascarid of cats and rarely of dogs. Also note two oocysts of Isospora felis.

An egg of Toxocara cati and an oocyst of Isospora felis.

Eggs of Toxocara cati (right) and Ancylostoma tubaeformae. (left)

Eggs of Parascaris equorum, the ascarid of horses. Notice the brown to yellow color and a thick, rough shell.

Parascaris equorum, these eggs may be found lacking the external shell covering making them appear colorless.

Elliptical perforation and a mass of Parascaris equorum. Rupture of the small intestines.

Eggs of Ascaris lumbricoides the ascarid of humans.

Eggs of Ascaris lumbricoides or Ascaris suum, the ascarid of swine.

Ancylostoma sp. Notice the smooth, thin outer shell which contains several cells that will quickly divide to form a morula (embryo)

Eggs of Uncinaria stenocephala very similar to Ancylostoma caninum but larger.

Ancylostoma tubaeformae occurs in cats, no real distinction from Ancylostoma caninum

Eggs of Ancylostoma caninum more common and more pathogenic

Eggs of Uncinaria stenocephala (Larger eggs) and Ancylostoma caninum (smaller eggs), also in the upper right hand corner Toxocara canis, one of the ascarids. Uncinaria sp. 65-80 microns. Ancylostoma sp. 55-65 microns

Eggs of Uncinaria stenocephala (larger eggs) and Ancylostoma caninum (smaller eggs)

Hookworm anemia- pale mucus membranes, weakness, and death. Puppies may succumb to the infection before the eggs are detectable in the feces.

Hookworm infection in a puppy, bloody feces characterized by dark tarry, chocolate brown stools.

Eggs of Toxocara canis and Toxascaris leonina, both species can be found in dogs, foxes, and coyotes. The small eggs are Ancylostoma caninum.

Toxocara cati and Ancylostoma tubaeformae found in cat feces.

Eggs of Ancylostoma caninum observed in various stages of segmentation.

First stage larvae of hookworms can hatch in about 48 hours.

Larvae of hookworms may become desiccated by the flotation solution.

Trichuris sp. (whip-like) the thicker end is the posterior end. They can be several centimeters long.

Trichuris vulpis, the whip worm of dogs. Notice the egg is brown in color, barrel shaped, has bipolar plugs, and a smooth outer shell.

Trichuris campanula, infrequent parasite of cats

End on end orientation of the Trichuris sp. (at arrow), this can disguise the characteristics.

Trichuris vulpis and Alaria canis, the stomach fluke.

Trichuris vulpis and Ancylostoma caninum

Trichuris vulpis on the mucosa of the colon

Eggs of Trichuris vulpis, the whipworm of dogs and wild canids.

Eggs of Trichuris vulpis not to be confused with lungworms which have a rough outer shell.

Eucoleus aerophila similar to Trichuris sp. But has a stubbier shape and is pale in color

Eggs of Trichuris suis, the whipworm of swine. X100

Egg of Trichuris suis X400

Aelurostrongylus sp. Note the kinked tail which is characteristic of lungworms.

Egg and larvae of Dictyocaulus arnfeldi, the lungworm of horses. These were taken from bronchial exudate. Only the larvae are found in the feces.

Eggs, part of a larvae, and an empty shell of Dictyocaulus arnfeldi. X400

Eggs of Dictyocaulus filaria, the lungworm of sheep, goats, and deer. They are embryonated when laid but usually hatch before they leave the host in the feces.

Eggs of Strongyloides papillosus the intestinal thread worm of cattle, sheep and swine. X400

Metastrongylus apri, one of the lungworms of swine recovered from bronchial exudate. X100

Rhabditiform larva of Strongyloides stercoralis, the intestinal "threadworm" of dogs, foxes, cats and man. The eggs hatch in the intestinal mucosa.

Strongyloides larva normally appear in fresh feces of infected dogs, the eggs are usually not seen.

Strongyloides stercoralis X400