1. General Considerations

   1. Hookworm dermatitis in dogs is also called ancylostomiasis or uncinariasis dermatitis.
   2. Lesions occur as a result of the cutaneous penetration of the third stage larvae of Uncinaria stenocephala and Ancylostoma spp.
   3. The larvae are located in the soil that the animals contact.
   4. Lesions are more often associated with Uncinaria stenocephala infestation because Uncinaria stenocephala rarely completes its life cycle by percutaneous penetration, however, Ancylostoma spp. can.
   5. The larvae enter the skin primarily at areas of desquamation but occasionally they may enter via hair follicles.
   6. Hookworm dermatitis has also been reported in cattle and sheep.
   7. Dermatitis is caused by larvae of the hookworm Bunostomum spp..

2. Cause

   1. Third stage larva of the nematode Uncinaria stenocephala or Ancylostoma spp in dogs.
   2. Infective larva of the nematode Bunostomum spp. in cattle and sheep.

3. Clinical Signs

   1. The condition is more frequently noticed in hookworm-infested dogs that are housed on dirt runs with poor sanitation.
   2. Lesions are primarily located on the paws but they may be seen on any area of the skin that contacts the ground.
   3. Erythematous papules are present initially but chronically affected skin often becomes diffusely erythematous, thickened and alopecic.
   4. Foot pads often become hyperkeratotic and may fissure.
   5. The interdigital spaces may be erythematous and the paws may eventually become soft and spongy, especially at the paw pad margins.
   6. The nails may grow faster, become deformed and break off in severe cases.
   7. Arthritis of the interphalangeal joints may be present.
   8. Pruritus is always present but it can vary in intensity.
   9. In cattle and sheep maintained in wet and muddy conditions, repeated cutaneous penetration by infectious larvae of Bunostomum spp. may produce a pruritic, erythematous, papular dermatitis especially on the hooves and legs. Affected animals are often irritable and stomp, kick, and lick the affected areas.

4. Diagnosis

   1. History of being housed on dirt and moist/muddy soil and poor sanitation.
   2. Suggestive clinical signs.
   3. Skin scrapings are often negative. Skin biopsy should be considered when skin scrapings are negative but it not always demonstrates the larva.
   4. A positive fecal exam for hookworm eggs provides supporting evidence but does not confirm a diagnosis.
   5. Differential diagnoses in dogs include atopic dermatitis, demodicosis, contact dermatitis, and pelodera dermatitis.

5. Treatment

   1. All affected and in-contact animals should be given appropriate anthelmintic treatment and a prophylactic program should be started. Examples of anthelmintics include thiabendazole, fenbendazole and levamizole.
   2. Frequent removal of feces from the contaminated environment as well as improved sanitation should be initiated.
   3. Sodium borate 4.5 kg per 30 m² may be used to destroy larvae on the ground but this treatment will kill the vegetation.

References

Chu S, Myers SL, Wagner B et al. Hookworm dermatitis due to Uncinaria stenocephala in a dog from Saskatchewan. Can Vet J 2013; 54: 743–747.

Scott DW. Parasitic Diseases.  Large Animal Dermatology. 1st edn. Philadelphia, PA: W.B. Saunders, 1988;  266-267.

Scott DW, Miller WH, Griffin CE:  Parasitic Skin Diseases.  Small Animal Dermatology. 5th edn. Philadelphia: W.B. Saunders Co., 1995; 393-395.