Meningeal Worm in Central Iowa Goat Herds

Aberrant migration of the deer meningeal worm, Parelaphostrongylus tenuis, is a commonly recognized cause of neurologic disease in South American camelids but is less frequently considered in other small ruminant species. After an unusually cool and wet summer season, central Iowa goat herds serviced by Iowa State University’s Veterinary Field Services have been increasingly affected by P. tenuis, with clinical cases presenting as early as August. Most caprine cases present with progressive neurologic deficits, starting with hind-end weakness and ataxia which may lead to complete paresis and death. Both sporadic cases and herd outbreaks involving as much as 15% of the herd have been observed. These cases involve a range of ages from older pre-weaned kids (4-6 months) to mature animals. Herds browsing wooded areas with a high deer density appear to be especially at risk. Field diagnosis is based on exposure history, clinical presentation, cerebrospinal fluid analysis, and response to treatment. Treatment protocols include extra-label high-dose, extended course fenbendazole, anti-inflammatories, and supportive care along with single dose ivermectin for control of immature larvae. Ambulatory animals generally respond to treatment but may retain residual neurologic deficits; prognosis for downer animals is poor. Control effort may include restricting access to high-risk browse or grazing sites, exclusion of deer and mollusks, and chemoprophylaxis