Canis ISSN: 2398-2942

Filaroides hirthi

Synonym(s): F. hirthi

Contributor(s): Stephen Barr

Introduction

Classification

Taxonomy

  • Superfamily: Metastrongyloidea.
  • Genus: Filaroides.
  • Species: Hirthi.

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Clinical Effects

Epidemiology

Habitat

  • Adults, eggs and larvae in lung alveolar and bronchial spaces.
  • L1 in sputum and feces.

Lifecycle

  • See lifecycle diagram.
    • Adult.
    • 1st stage larva.

Transmission

Transmission from bitch to puppies
  • L1 in respiratory secretions is carried out of the mouth with partly digested food that is being regurgitated to feed the pups.
  • Coprophagy and licking also relevant.
Transmission to other dogs
  • L1 passed in the feces or vomitus are fully infective if these are eaten relatively fresh.
Internal autoinfection
  • L1 are swallowed and, in immunosuppressed dogs, are able to migrate directly from the intestine back to the lungs.

Pathological effects

  • In hyperinfected dogs, worms, eggs and L1 are distributed throughout the lung parenchyma.
  • Interstial and nodular infiltrates around worms (but particularly around eggs and L1), form granulomata that appear grossly as small grayish nodules that may coalesce to form masses.

Control

Control via animal

  • Anthelmintic treatment.
  • Separation of dogs so that they have no access to feces or vomitus.
  • Derive puppies by Caesarean section and hand rear them in separate kennels. However, it is not known whether or not prenatal transmission could occur in dogs with auto-infection.

Control via chemotherapies

  • Albendazole Albendazole : (25 mg/kg bid for 5 days) (not licensed for use in dogs).
  • Ivermectin Ivermectin or millbemycins might be tried. Ivermectin (at 50 mcg/kg), is reported to have effect.
  • Fenbendazole Fenbendazole : (50 mg/kg/day for 14 days) (unlicenced use).

Control via environment

  • Removal of all feces immediately when passed.
  • Larvae are rapidly killed by desiccation.

Diagnosis

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Further Reading

Publications

Refereed papers

  • Recent references from VetMed Resource and PubMed.
  • Bahnemann R & Bauer C (1994) Lungworm infection in a Beagle colony - Filaroides hirthi, a common but not well known companion. Experimental Toxicol Pathol 46, 55-62. (Pathology in relation to toxicological studies.)
  • Bourdeau P & Ehm J P (1992) Filaroides spp. infection in dogs. A case report and an update on filaroidosis caused by Filaroides hirthi Georgi and Anderson 1975. Recueil de Medicine Veterinaire 168, 315-321. (Review.)
  • Georgi J R (1986) Parasites of the respiratory tract. Vet Clin N Am Small Anim Pract) 17, 1421-1442. (Review.)

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