Helminthiasis may also refer to ancylostomiasis, but this term also refers to all other parasitic worm diseases as well Ancylostomiasis is a hookworm disease caused by infection with Ancylostoma hookworms. The name is derived from Greek ancylos αγκύλος "crooked, bent" and stoma στόμα "mouth". braziliense, and Uncinaria stenocephala. Hookworm infection is one of the most common diagnoses in canine practice, and A. caninum is by far the most prevalent species involved. Ancylostoma eggs were identified in 19% of canine fecal samples collected from various locales in the United States [6]. Ancylostoma caninum infections can be acquired by vertical (transmammary) transmission, percutaneous invasion, or ingestion of infective third-stage larvae or paratenic hosts. In mature dogs with some acquired immunity, infective larvae may not develop directly into adults, but rather migrate to somatic tissues such as kidney and skeletal muscle, where they undergo prolonged arrested development [7]. These arrested larvae are most commonly reactivated by the hormones of pregnancy and lactation, and larvae are transmitted to suckling pups in the bitch’s milk. Although hookworm infection is observed in dogs of all ages, pups and juveniles are more likely to exhibit clinical signs of disease, including anemia, weakness, melena, anorexia, and weight loss or poor growth. As with most parasitisms, clinical signs are exacerbated by malnutrition, stress, or concurrent disease. Hookworm disease (ancylostomosis) has been classified as four distinct syndromes which vary with the age, route of infection, or overall health status of the animal. In peracute ancylostomosis, suckling pups around 2–3 weeks of age die of severe anemia with no preceding clinical signs, due to overwhelming hookworm infections acquired through the transmammary route. Acute ancylostomosis involves slightly older or weaned pups that survive long enough to develop melena and signs of severe anemia. Again, transmammary infection is the usual route. The two remaining classifications of ancylostomosis occur in mature dogs that are either repeatedly exposed to L3 stages or are continuously reinfected with larvae activated from their arrested, somatic pools. Uncompensated ancylostomosis occurs when malnutrition or co-morbid disease render an animal incapable of managing hookworm insults through immunologic or general defense mechanisms. In contrast, no clinical signs are seen in dogs with compensated ancylostomosis, which is a term used to describe recurrent infections that are partially controlled, but not eliminated, by host mechanisms. Compensated ancylostomosis is typically recognized when fecal examinations after repeated treatments document the incessant reappearance of hookworm eggs. Products labeled for treatment or removal of Ancylostoma caninum are the appropriate therapeutic choice for apparently healthy dogs or those with moderate signs of ancylostomosis (ie, compensated and uncompensated cases). Suckling pups with acute ancylostomosis require immediate and vigorous medical attention. Pyrantel pamoate/embonate is the preferred anthelmintic for this syndrome, due to its speed of activity and broad safety in debilitated animals. Ancillary medical management (eg, iron supplementation) is critical, but pups with acute ancylostomosis often make very dramatic recoveries once the immediate source of blood loss has been eliminated. By definition, anthelmintic treatment would arrive too late to salvage pups with peracute ancylostomosis, but surviving littermates should be treated promptly as for the acute syndrome. Specific regimens of pyrantel pamoate have been designed to reduce the clinical impact of hookworm infections in suckling pups. These are described in greater detail in the section on Toxocara canis. Current standards of care support the maintenance of all canine patients on some form of heartworm prevention, and all currently marketed Dirofilaria preventives are anthelmintics of the macrocyclic lactone (ML) class. Several heartworm preventive products have been developed in which the ML component is combined with other anthelmintics, including pyrimidines, to provide a broader spectrum of nematode control. Because most MLs also exhibit activity against hookworms, some of these combination products achieve higher efficacy against hookworms than either component used singly. For example, HeartGard Plus (ivermectin plus pyrantel pamoate) was more than 99% effective against adult Uncinaria stenocephala whereas pyrantel pamoate alone exhibited 93.4–96.3% efficacy [8]. Regular, monthly administration of such combination products reduces environmental contamination with hookworm eggs, and thereby reduces the risk of compensated or uncompensated ancylostomosis in mature dogs. Uncinaria stenocephala is a less common hookworm of dogs that is most often acquired through ingestion of third-stage larvae (L3s). Uncinaria is more restricted in its geographic distribution than Ancylostoma caninum, occurring more frequently in Europe, Canada, and the northern tier of the United States. Uncinaria eggs were found in only 1.02% of canine fecal samples collected from around the United States [6]. Uncinaria ingests plasma proteins rather than whole blood, so clinical signs are primarily related to the gradual loss of vital nutrients. Ancylostoma braziliense is another fairly nonpathogenic hookworm of dogs that is limited to tropical and subtropical climates. Routine Uncinaria and A. braziliense infections can be managed with approved anthelmintics containing pyrantel pamoate/embonate. Transmammary transmission does not occur with either species, so special regimens for suckling pups are not required. Some monthly heartworm preventives are also labeled for efficacy against U. stenocephala and A. braziliense (eg, HeartGard Plus). Regular control is advisable in endemic areas because both U. braziliense can cause a zoonotic condition known as cutaneous larva migrans [9].
