Crenosoma spp

From Dog
Egg of C. vulpis under light microscopy[1]
First-stage larvae of C. vulpis recovered using Baermann technique[1]

Crenosoma spp (fox lungworm) are a parasitic nematode of the bronchi, bronchioles, and trachea of dogs[2].

Species which are pathogenic to dogs include:

  • Crenosoma vulpis

The life cycle of this parasite involves a paratenic host (usually snails) and encysted infective larvae within the mollusc are ingested by dogs. The larvae are proteolytically activated by gastric acids in the stomach and undergo visceral migration to finally reside in the pulmonary tree of dogs. Adult worms within the lungs deposit eggs in the alveoli and these ascend via ciliary action into the oropharynx, where they are swallowed, and are shed in the feces. Fecal eggs are ingested by snails to complete the cycle. The prepatent period is approximately 3 weeks[3] in dogs.

Clinically signs are usually mild compared with other cardiopulmonary parasites such as Dirofilaria immitis, Angiostrongylus spp and Eucoleus spp[4]. Fatal cases have never been reported in dogs[5].

A chronic insidious cough predominates, with some dogs presenting with hemoptysis, signs not dissimilar to dogs with allergic respiratory disease. Clinicians failing to consider C. vulpis infection in cases of dogs suffering signs of chronic cough are most likely to misdiagnose and treat the condition as asthma or an allergic disease.

Hematological parameters are usually nonspecific, although eosinophilia is common.

Diagnosis usually involves coprological examination using a Baermann flotation device. Bronchoalveolar lavage are usually performed and larva are regularly found[6].

ELISA assays are usually indicative of C. vulpis infection and PCR assays are a definitive test.

Treatment is relatively effective with fenbendazole, milbemycin oxime (0.5 mg/kg weekly x 4)[7], doramectin, selamectin, ivermectin or daily diethylcarbamazine[8].

Prednisolone (1 mg/kg q 24 hrs for 7 days, then reducing dose) may help ameliorate clinical signs while the anthelmintic drugs are taking effect[9].

References

  1. 1.0 1.1 Shaw DH et al (1996) Eosinophilic bronchitis caused by Crenosoma vulpis infection in dogs. Can Vet J 37(6):361-363
  2. Rinaldi L et al (2007) Crenosoma vulpis in dog: first case report in Italy and use of the FLOTAC technique for copromicroscopic diagnosis. Parasitol Res 101(6):1681-1684
  3. Bowman, DD (2009) Georgis' parasitology for veterinarians. 9th edn. Elsevier Saunders, Missouri. pp:186
  4. McGarry JW et al (1995) Crenosoma vulpis, the fox lungworm, in dogs. Vet Rec 137(11):271-272
  5. Traversa D et al (2010) Canine and feline cardiopulmonary parasitic nematodes in Europe: emerging and underestimated. Parasit Vectors 3:62
  6. Unterer S et al (2002) Spontaneous Crenosoma vulpis infection in 10 dogs: laboratory, radiographic and endoscopic findings. Schweiz Arch Tierheilkd 144(4):174-179
  7. Conboy G et al (2004) Natural infections of Crenosoma vulpis and Angiostrongylus vasorum in dogs in Atlantic Canada and their treatment with milbemycin oxime. Vet Rec 155(1):16-18
  8. Stockdale PH & Smart ME (1975) Treatment of crenosomiasis in dogs. Res Vet Sci 18(2):178-181
  9. Peterson EN et al (1993) Use of fenbendazole for treatment of Crenosoma vulpis infection in a dog. J Am Vet Med Assoc 202(9):1483-1484