Pathogenic species in dogs include:
- Brugia malayi
- Brugia pahangi
The life cycle of this parasite involves transmission of infective L1 larvae by mosquitoes, which subsequently feed on dogs and transmit infective L3 larvae. Adult Brugia spp usually reside in the mandibular, retropharyngeal and axillary lymphatics.
An intimate relationship exists between Brugia spp development, reproduction and survival and the endosymbiontic alphaproteobacteria Wolbachia spp, and needs to be understood to understand the etiopathogenesis of this disease in dogs. In filaria, Wolbachia is an obligate mutualistic symbiont that plays an essential role in oogenesis and embryogenesis in adult worms and during larval development. Symptoms of Brugia infection are correlated not so much with adult filariids but with Wolbachia-surface proteins, which induce an inflammatory response associated with the pathogenesis of onchocerciasis through the activation of an innate immune response. Elimination of Wolbachia by antibiotic treatment leads to infertility of the female worms, inhibition of larval molting, and atrophy and death of adult worms (macrofilaricidal effect).
Serological surveys show high prevalence of this parasite in South-East Asia and India.
Clinical signs in dogs usually involves lymphadenopathy and lymphedema, but this can be complicated in dogs with co-infections with D. immitis. Limb edema, particularly unilateral hind limb involvement is commonly observed. In selective breeding studies with beagles, occult infections appears to be more pathogenic than dogs with microfilaremia, underlying the role genetics play in clinical manifestations with this disease.
Treatment with doxycycline is relatively effective at eliminating Wolbachia spp which resides in the reproductive tract of brugia. Doxycycline given at 10 mg/kg orally twice daily for 30 days has efficacy against migrating tissue-phase larvae and juvenile worms and will delay or restrict microfilarial production.
- Lincoln. ac.uk
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