Light micrograph of the eggs of the dog roundworm Toxocara canis. The larvae cause toxocariasis, a parasitic infestation due to ingestion of material contaminated by eggs deposited in dog feces. They migrate around the body destroying various tissues; the liver may enlarge and the lungs become inflamed. Symptoms include fever, joint and muscle pain, vomiting and convulsions; larvae lodging in the retina of the eye cause inflammation and granuloma. Magnification 450x @ 35mm.