Endoparasites

Endoparasites

1. Roundworms (Nematodes)

   • Toxocara cati
     • No migration
     • Lies dormant in cysts
     • Unborn kittens not affected
     • Can be spread in milk
   • Toxocara canis
     • Life cycle
       • 1. Infected dog passes Toxocara egg in faeces, milk and in utero
       • 2. Eggs pass in faeces
       • 3, Larva develops inside egg in environment
       • 4. Dog ingests larva/egg
       • OR dog can ingest an intermediate host (usually small mammals like squirrel
     • Signs
       • Could be none
       • Weight loss
       • Foul breath
       • Diarrhoea
       • Constipation
       • SEVERE
         • Anaemia
         • Bowel Obstruction
     • Pregnant Bitches
       • Prenatal Infection
         • Larvae mobilised 3 weeks prior to parturition
           • Then migrate to lungs of foetus
             • Then to intestines via tracheal migration
     • Dogs up to 3 months old
       • after ingestion, larvae hatch in small intestines
         • Larvae then travel in blood stream via liver and lungs (2nd moult)
           • Larvae are then coughed up and swallowed back to intestines
           • HEPATIC-TRACHEAL MIGRATION
     • Dogs over 3 months old
       • Hepatic-tracheal migration less common
         • larvae instead travel to tissues such as:
           • liver
           • lungs
           • brain
           • heart
           • gut
           • steletal

2. Tapeworm (cestodes)

   • Dipylidium caninum
     • Life cycle
       • 1. Head (scolex) attaches to small intestine wall
       • 2. Terminal proglottides break off and pass with faeces
       • 3. Proglottids shed eggs on ground
       • 4. Flea larvae eat eggs
       • 5. Tapeworm larvae encyst in the flea and become infective
       • 6. Infective fleas ingested leading to infection of dog
   • Taenia
     • More common in cats
       • cats hunt intermediate hosts
     • intermediate host
       • birds
       • squirrels
       • mice
       • sheep
     • egg ingested in intermediate host:
       • onchosphere moves into blood, lymph or in invertebrates: the body cavity
     • Predilection sites
       • Echinococcus granulosus
         • Hydatid cysts
           • affects humans
             • in liver, lungs, brain
           • prolonged and painful
           • difficult to diagnose and treat
           • usually absorbed back into body
       • Taenia ovis
         • Cysticercus ovis
           • man not affected
           • in heart muscle of sheep
       • Taenia hydatigena
         • Cysticercus tenuicollis
           • Found in abdomen of grazing animals
           • economic loss due to tissue contamination
           • heavy infections cause liver damage
       • Taenia multiceps
         • Coenurus cerebralis
           • Rare in men
           • GID