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275.e2 Draining Tracts, Cutaneous

extraction using blunt dissection is recom- Recommended Monitoring Technician Tips
mended. Antiinflammatory drugs may ease Visual assessment of healing The use of a compound microscope to detect
VetBooks.ir • There is no proven effective medical treat- PROGNOSIS & OUTCOME with their characteristic long tails is the key
removal.
the presence of the unique first-stage larvae
ment; surgical extraction is recommended.
to diagnosis.
Experimental treatments include niridazole
12.5 mg/kg PO q 12h for 10 days, or Excellent prognosis if the parasite is surgically Client Education
extracted and no portions remain in situ
thiabendazole 50 mg/kg PO q 24h for 2 Dogs should not be allowed to roam freely to
to 3 days. PEARLS & CONSIDERATIONS avoid contact with infested water.
• A single worm is contained in each ulcerative
lesion. After the entire gravid female worm is Comments SUGGESTED READING
extracted, healing should take place quickly. • These worms are singular in their appearance Beyer TA, et al: Massive Dracunculus insignis infection
• Ivermectin or fenbendazole for 7 to 10 days in ulcerated skin lesions. in a dog. J Am Vet Med Assoc 214:351, 366-368,
can interrupt infection if given within 90 • Although this nematode is rare, it is easy to 1999.
days, but early recognition of infection is diagnose.
not possible. • D. insignis is closely related to the human ADDITIONAL SUGGESTED
scourge, D. medinensis, the human Guinea READINGS
Chronic Treatment worm, the “serpent on the stick,” or the Johnson GC: Dracunculus insignis in a dog. J Am
As needed for dermatologic complications: serpent of the staff of Aesculapius, the symbol Vet Med Assoc 165:533, 1974.
• Secondary bacterial infection of the medical/veterinary professions. Panciera DL, et al: Dracunculus insignis infection
• Cellulitis • The old school/Old World therapy of remov- in a dog. J Am Vet Med Assoc 192:76-78, 1988.
• Culture and sensitivity of skin lesion with ing D. medinensis in humans is to tie the AUTHOR: Charles M. Hendrix, DVM, PhD
appropriate antimicrobial therapy worm to a small stick and gradually roll the EDITOR: Joseph Taboada, DVM, DACVIM
worm up over the course of a few days or
Behavior/Exercise weeks. Dogs are not likely to tolerate this
An Elizabethan collar may be indicated until therapy.
the lesion is healed.
Prevention
Possible Complications Prevent dogs from roaming and coming into
Breaking the friable body of the female worm in contact with freshwater aquatic environments
situ and not being able to recover the remnants containing Cyclops species harboring infective
of the parasite larvae of D. insignis.

Draining Tracts, Cutaneous Client Education
Sheet

BASIC INFORMATION ASSOCIATED DISORDERS • Exudate from the tracts may be serous,
• Frequently associated with cutaneous nodular serosanguineous, or purulent. Tissue granules
Definition disease (e.g., actinomycosis, actinobacillosis, nocar-
A fistulous connection between an area of • May be associated with additional systemic diosis, and bacterial pseudomycetoma) may
subcutaneous or deeper soft-tissue inflammation signs, depending on the cause be found in the exudate.
and the skin surface
Clinical Presentation Etiology and Pathophysiology
Epidemiology DISEASE FORMS/SUBTYPES Infectious causes are often the result of direct
SPECIES, AGE, SEX • Infectious inoculation of the organism into the subcu-
Varies, depending on cause • Noninfectious taneous tissue by penetrating injury. Foreign
• Neoplastic material often remains as a sequestrum at
RISK FACTORS the site of a penetrating wound, leading to
Penetrating injuries, chronic exposure of the HISTORY, CHIEF COMPLAINT draining tracts. Plant awns, porcupine quills,
skin to trauma or moisture, wound con- There may be a history of a previous penetrat- or other foreign bodies may penetrate through
tamination, contact with infected individuals, ing injury, typically associated with infectious the skin or other orifices (e.g., gastrointestinal
immunodeficiency syndromes causes. For all forms/subtypes, a common tract, respiratory tract) and then migrate to
complaint is a non-healing cutaneous wound distant body sites. Unlike other infections,
CONTAGION AND ZOONOSIS that fails to respond to antimicrobial therapy systemic mycoses (e.g., blastomycosis, coc-
Pathogens with zoonotic potential are Nocar- or that recurs after antimicrobial therapy has cidioidomycosis, cryptococcosis) are acquired
dia, Blastomyces, Sporothrix, Leishmania, and been discontinued. mainly through inhalation and only rarely
others. through direct inoculation. Immunosup-
PHYSICAL EXAM FINDINGS pressive diseases may increase the risk of
GEOGRAPHY AND SEASONALITY • Lesions may be solitary or multiple. infection or colonization with opportunistic
• In warm, dry climates, grass awns can become • Draining tracts are often associated with pathogens.
penetrating foreign bodies. cutaneous nodules (fungal or bacterial • Bacterial (including feline subcutaneous
• Some infectious causes (including systemic granuloma, idiopathic sterile pyogranuloma/ abscesses, actinomycotic infections [Acti-
fungal infections) are endemic to geographic granuloma, sterile nodular panniculitis). nomyces, Nocardia], Streptomyces griseus,
regions. • Lesions may or may not be painful. Dermatophilus congolensis, actinobacillosis,

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