Hookworm Dermatitis

Hookworms have been regarded as the most faithful intestinal parasites of dogs and cats. Indeed, they are responsible for developmental impairment, severe clinical signs and high death rate, especially in young subjects. These worms live anchored to the gut mucosa by their oral capsule and have a relevant blood-sucking activity. Indeed, while Ancylostoma braziliense may present a mild pathogenic impact, the other hookworms are intensive hematophagous and cause important exsanguination. In general, ancylostomosis in pets induces a mild enteritis to a fatal hemorrhagic diarrhoea with anemia, depending upon different drivers, e.g. age of the animal, parasitic burden and species involved.

Hookworm dermatitis, also called ancylostomiasis or uncinariasis dermatitis is a skin disease caused by infestation of the small intestine by worms. Different species of ascarids (commonly known as "roundworms") and ancylostomatids (commonly known as "hookworms") may affect the small intestine of dogs and cats. Actually, they remain the most important parasites affecting companion animals worldwide and maintain the primacy in terms of dispersion and risk for animal and human health. This is of particular importance also because some driving forces are nowadays favouring their spread, such as the increase of wild fox populations in suburban and urban areas. The majority of canine and feline roundworms and hookworms are potentially zoonotic.2

Hookworm larva

Hookworms have a complex biological cycle, in which different sources and ways of infection are possible. The most important infectious stage is represented by filariform larvae present in the soil, which infect a suitable host by actively penetrating the skin (especially for Ancylostoma species) and/or via the oral route (Ancylostoma and Uncinaria species). The worms enter the body through the skin leaving an itching rash, travel to the lung via the blood and lymph system, ascend the respiratory tract and are swallowed. Lesions occur as a result of the skin penetration of the third stage larvae of Uncinaria stenocephala and Ancylostoma species. Although the larvae enter the skin primarily at areas of scaling skin, occasionally they may enter via hair follicles.

The condition is more frequently noticed in hookworm infested dogs that are housed on dirt runs with poor sanitation. Lesions are primarily located on the feet but, they may be seen on any area of the skin that contacts the ground. Papules are present initially but, chronically affected skin often becomes red, thickened and alopecic. The interdigital spaces may be red, and the feet may eventually become soft and spongy especially at the pad margins. The nails may grow faster, become deformed and, in severe cases, break off. Arthritis may be present. Itchiness is always present but it can vary in intensity. Animals are irritable and lick their feet.



Diagnosis & Treatment

All affected and in-contact dogs should be given appropriate antihelminthic treatment and a prophylactic program should be started. Frequent removal of feces from the runs and kennels as well as improved sanitation should be performed. Therapy consists of routine worming with thiabendazole, fenbendazole, or levamizol. Tribendimidine is a diamidine derivative of amidantel, an older acetylcholine receptor drug used to treat hookworm. Treatment with tribendimidine has yielded cure rates similar to albendazole for intestinal taeniasis.3 Oral antibiotics are used in cases with confirmed or suspected concurrent bacterial infection. Since decaying organic matter is a typical habitat of P. strongyloides, removal of straw bedding from the kennel is imperative to allow successful medical treatment.

References

  1. Lila Miller, Kate Hurley (editors). Infectious Disease Management in Animal Shelters
  2. Pet roundworms and hookworms: A continuing need for global worming
  3. Antiparasitic Therapy


 

 


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