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934 Spirocercosis

GEOGRAPHY AND SEASONALITY DIAGNOSIS • Thoracic CT identifies significantly more
This parasite is found in the southern Diagnostic Overview esophageal masses, aortic aneurysms, aortic
VetBooks.ir tropical regions. In some endemic areas, Spirocercosis typically is suspected in a patient • Postmortem exam of patients with sudden
mineralization, and aortic thrombi.
United States and many tropical and sub-
living in an endemic area presented for evalu-
there is a disproportionately high prevalence
death or that have been euthanized can
among urban dogs compared with rural
dogs, but this varies with geographic ation of regurgitation. Thoracic radiographic provide a definitive diagnosis.
findings often support the diagnosis, but direct
region. visualization through endoscopy is required for TREATMENT
confirmation before treatment.
ASSOCIATED DISORDERS Treatment Overview
• Esophageal neoplasia (osteosarcoma, fibro- Differential Diagnosis Treatment goals:
sarcoma, undifferentiated sarcoma) may • Regurgitation: other esophageal disorders • Resolution of regurgitation or vomiting
occur secondary to esophageal granuloma such as megaesophagus, esophagitis, foreign • Prevent development of esophageal neoplasia
formation from the encysted worms. bodies, esophageal stricture, gastroesophageal or hypertrophic osteopathy.
• Hypertrophic osteopathy reflux disease • Prevent sudden death due to rupture of
• Thoracic aortic aneurysm and/or thrombosis • Esophageal mass: esophageal neoplasia, aneurysm.
may occur secondary to migration of S. lupi granuloma of other origin
from the gastrointestinal (GI) tract into the • Vomiting: gastrointestinal (GI) (inflam- Acute General Treatment
aortic wall. matory, infectious, parasitic, neoplastic, • Doramectin is treatment of choice. Perma-
• Thoracic vertebral spondylitis has been dietary) and extra-GI (metabolic, endocrine, nent resolution/cure is expected for many or
reported secondary to migration and pancreatitis) causes most dogs in 6 weeks or less. Two protocols
granuloma formation. are recognized:
• Salivary gland necrosis, esophageal perfo- Initial Database ○ Intermittent SQ protocol: 200 mcg/
ration with associated mediastinitis and • CBC, serum biochemical profile, urinalysis; kg SQ q 14 days for 3 treatments; if
pyothorax have also been reported. no characteristic abnormalities necessary (incomplete resolution of
○ Anemia (53% of cases) typically normo- lesions), retreatment with 500 mcg/kg
Clinical Presentation cytic, normochromic, and nonregenerative PO q 24h × 6 weeks has been successful
HISTORY, CHIEF COMPLAINT ○ Leukocytosis (primarily neutrophilia) and safe.
May be subclinical or clinical signs reflecting ○ Elevation in serum creatine kinase level: ○ Daily PO protocol: 500 mcg/kg PO q 24h
location of lesion: vomiting or regurgitation, most common biochemical abnormality × 42 days (65% cured); if lesions persist,
odynophagia, ptyalism, weakness, respira- (54% of cases) can retreat × 42 days once (further 25%
tory difficulty, coughing, anorexia, melena, ○ Hyperproteinemia due to hyperglobulin- cured) or twice (remaining 10% cured)
paraparesis emia more
• Fecal flotation NaNO 3 (specific gravity [SG] • Fenbendazole 50 mg/kg PO q 24h × 5-7 days
PHYSICAL EXAM FINDINGS 1.22), MgSO 4 (SG 1.29), ZnSO 4 (SG 1.30), or ivermectin 200-400 mcg/kg SQ q 14-28
In addition to the chief complaints listed above, or sugar (SG 1.27) days has been used for treating spirocercosis.
the most common abnormalities are weight ○ May reveal characteristic small, elongated
loss and fever. eggs; positive result in 42%-67% of Possible Complications
endoscopically confirmed cases (NaNO 3 Do not use ivermectins (like doramectin) in
Etiology and Pathophysiology best) collies, Shetland sheepdogs, Australian shep-
• Spirocercosis is caused by migration of the • Thoracic and abdominal radiographs are herds, or other susceptible breeds or individuals
nematode S. lupi. Carnivores are infected indicated (dorsoventral and right lateral unless MDR1/ABCB1-Δ mutation negative
by ingestion of an intermediate host projections most accurate for thoracic films) (p. 638).
(coprophagous beetles) or other paratenic and may reveal
hosts (e.g., birds, hedgehogs, lizards, mice, ○ Esophageal and stomach lesions (soft-tissue PROGNOSIS & OUTCOME
rabbits) in which the parasite does not masses with/without calcification): a
undergo further development during its mass is noted in the caudal esophagus Prognosis is variable:
passage. in 53%-86% of cases of spirocercosis. • With appropriate treatment, cure is
• Adult S. lupi generally live in esophageal Most affected dogs have more than expected for many or most dogs in 6 weeks
and gastric nodules. Spirocerca eggs pass one granuloma, but not all are visible or less.
with feces, and they are ingested by radiographically. ○ Daily protocol: > 97% of dogs have
coprophagous beetles. The definitive host ○ Insufflation of the esophagus with air resolution of clinical signs after 7-10 days
may acquire the infection by ingesting the (sedated/anesthetized patient) significantly of treatment.
beetle intermediate host or other paratenic improves diagnostic yield. • Esophageal neoplasia, aortic aneurysm, or
host. ○ Bony changes in the thoracic vertebrae large masses obstructing flow of ingesta
• L3-stage larvae penetrate the stomach wall ○ Evidence of metastasis possible when worsens the prognosis.
of the definitive host, migrate in the walls of esophageal neoplasia is present • Hypertrophic osteopathy signifies a worse
the gastric arteries to the thoracic aorta, and • Limb radiographs of patients with lameness prognosis (39% of cases with esophageal
then migrate to the esophagus. The prepatent or hard swelling of distal limbs to assess for malignancy, 0% of cases without esophageal
period, the time from infection of the host to hypertrophic osteopathy malignancy)
the first ability to detect the infection with • Radiographic evidence of spondylitis (68%
diagnostic evaluation, is approximately 5-6 Advanced or Confirmatory Testing vs. 38%) and bronchial displacement (52%
months. • Esophagoscopy and gastroscopy (p. 1098) vs. 17%) is significantly more likely in those
• Clinically significant lesions reflect the may allow visualization of granulomas with malignancy.
migration route and final destination of and biopsy. In most cases of spirocercosis, • Sixty-three percent of dogs with spirocercosis
the parasite. The most common scenario is endoscopy is the confirmatory diagnostic may die or be euthanized within 1 month
esophageal granuloma formation. procedure of choice. of admission.

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