Crenosoma vulpis
The lungworm Crenosoma vulpis is a worldwide species of parasite that typically affects Vulpes sp. (True foxes), however it can secondarily affect canines such as Canis familiaris (pet dogs), so C. vulpis of high importance for eradication – owing to the economic importance of the pet industry.
The symptoms of C. vulpis are not dissimilar to classis respiratory allergic reactions leading to common confusion in diagnosis by the owner; these worms are known to cause a build-up in catarrhal inflammation which is relatively mild and cause no nodule formation inside the bronchi [1]. Rarely will this inflammation amount to more than a cough, however L3 can incite pneumonia, while adult worms can cause bronchitis and bronchiolitis in some cases. Endoscopy has shown that damage typically includes: bronchial haemorages, irregular mucosal surfaces, mucosal erythema (redness) as well as purulent exudate [2]
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Lifecycle
The lifecycle for these C. vulpis begins in the lumen of the bronchi in either foxes or dogs, wherein the adult female worm produces eggs which will develop into larvae (L1). These are carried to the digestive system by the trachea and excreted in faecal matter. L1 then penetrate the foot of mollusc host (snails or slugs) and will have developed into L3 after approximately 3 weeks. At this point they in infective and may be ingested by either Vulpes sp. or Canis sp. Once ingested they are released by digestion and will travel to the lungs by either the lymphatic glands or by circulation through the hepatic portal system. It is here that both moults from L4 into L5 will take place (pre-adults) wherein they develop normally into fully fledged adult worms and continue the cycle. [2]
The prepatent period (time for infection after ingestion) is 19 days [1].
Identification [3,4]
Anterior end: 18 to 26 cuticular folds that encircle the body and give the worms their crenated appearance.
Adult males: 3.5 – 8mm length
Adult females: 12-16mm length, ovoviviparous
L1 Larvae: 200 μm long with the oral ends bluntly conical and the tips of the tails tapering smoothly to the end without any kink, undulation, or spine. The esophagus is about one-third of the total body length.
Other varieties of lungworm
Lungworm in cattle – Dictyocaulus viviparus
Lungworm in sheep – Dictyocaulus filaria
Lungworm in cats –
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Bibliography
- https://capcvet.org/guidelines/crenosoma-vulpis/
- Unterer S, Deplazes P, Arnold P, Flückiger M, Reusch CE, Glaus TM. Spontaneous Crenosoma vulpis infection in 10 dogs: laboratory, radiographic and endoscopic findings. Schweiz Arch Tierheilkd. 2002; 144:174-179.
- Wetzel R. Zur biologie des fuchslungenwurmes Crenosoma vulpis. Arch Wiss Prakt Tierheilk. 1940;75:445–450.
- McGarry JW, Morgan ER. Identification of first-stage larvae of metastrongyles from dogs. Vet Rec. 2009;165:258–261. doi: 10.1136/vr.165.9.258.