Introduction

• Cause: classical hookworm disease caused by Ancylostoma species, particularly A. caninum.
• Rare in the UK and when present likely to be caused by the "northern hookworm" Uncinaria stenocephala. Common in the US and more southern parts of mainland Europe.
• A. caninum now recognized as a zoonosis.
• Signs: hookworm disease severity and clinical signs depend to a large extent on the species of hookworm: anemia (A. caninum), lethargy, inappetence, diarrhea (may be black and tar-like in A. caninum), dermatitis.
• Diagnosis: signs, worms seen.
• Treatment: anthelmintics and environmental control.
• Prognosis: good with appropriate treatment.

Pathogenesis

Etiology

• Hookworm disease is caused by infection with immature or adult hookworm population.

Predisposing factors

General

• Access to grass or sand runs. Dog racetracks and greyhound rearing and training facilities make ideal breeding grounds for hookworms due to the sandy ground. 
• Inadequate worm control.
• Warm, wet weather (so disease maybe seasonal in incidence, eg may be seen in autumn after a warm wet summer).

Specific

• Acute and peracute A. caninum infection associated with sudden infection with a large number of larvae (though 50-100 adult worms may be sufficient to kill a pup).
• Disease may be seen before the worms reach adulthood, ie in the pre-patent period.
• Chronic infection associated with prolonged exposure to a significant hookworm population.

Pathophysiology

• Worms ingest blood and tissue fluid and damage small intestinal mucosa so that blood/fluid loss continues even when the worm itself has moved to a new feeding site.
• In acute or peracute A. caninum infection, severe anemia is caused and the animal has no time to compensate for the degree of blood loss.
• In a chronic A. caninum infection, clinical signs may be seen if the rate of blood loss exceeds the animal's capacity for compensation.
• A. caninum peracute infection where suckling pups receive a large infection of larvae from the dam in the milk.
• Acute symptoms may also be seen in an older pup that receives a sudden large challenge for the first time.
• A. caninum Ancylostoma caninum are voracious blood suckers and possess teeth within their buccal capsules to slash the mucosa.
• As worms move to fresh feeding locations they leave bleeding ulcers.
• A. caninum worms can remove 0.1 ml blood per worm per day.
• A. braziliense is less pathogenic removing only in the region of 0.008 ml blood per worm per day.
• U. stenocephala worms damage the mucosa, resulting in protein losing enteropathy. Blood loss less severe.
• Eggs passed in feces embryonate and hatch into infective larvae within a week in ideal conditions.
• Dogs then reinfected when they ingest infective third stage larvae.
• A. caninum infection may occur through the percutaneous route.
• Main source of A. caninum infection for neonates is remobilization of resting L3 larvae from the somatic tissues of the bitch to the mammary gland.
• Pass in the milk to the pups.
• Transplacental transmission does not occur or not to any significant extent.

Timecourse

• A. caninum larvae pass in the milk to pups from birth, clinical signs typically seen in second week after birth.
• Pre-patent period approximately 16 days.

Epidemiology

• See A. caninum Ancylostoma caninum and Uncinaria stenocephala Uncinaria stenocephala.

Diagnosis

Treatment

Prevention

Outcomes