Hookworms are intestinal parasites causing significant blood loss and malnutrition in infected dogs, with puppies particularly vulnerable to life-threatening anemia from heavy infections.
Hookworm infections cause suffering that ranges from subclinical but ongoing in mild cases to critically life-threatening in severe infections. Puppies with heavy hookworm burdens become progressively anemic - pale, weak, unable to thrive, with the characteristic tarry stools of gastrointestinal blood loss. Without treatment, severely infected puppies die from blood loss. Adult dogs with moderate infections experience chronic blood and protein depletion that impairs immune function, reduces energy, and degrades coat condition - ongoing welfare harm that may be mistaken for poor condition due to inadequate nutrition. The human health dimension of hookworm infection (larva migrans) also creates public health risks in environments contaminated by infected dog feces.