Cats and dogs cestodes and trematodes Flashcards
Epidemiology/ecology of Taeniids
Adults found in both canids and felids. Larval stages found in a variety of hosts
Global distribution
Predator-prey based indirect life cycle
Carnivore definitive hosts
Herbivore intermediate hosts
Eggs immediately infective and resistant in the environment (months)
Prevalence in DH tends to increase with age
Characteristics of Taenia spp
Have a rostellum with hooks and suckers on the side
One genetialia per mature segment - hermaphrodite
Life cycle of Taenia spp
Eggs in feces
Egg contains a single hecanth larvea
IH with metacestode with protoscolex eater
takes 2-3 months to develop in IH
PPP 6-9 weeks
Common Taenia spp. tapeworms in Canada
Taenia hydatigena
T.pisiformis*
T.ovis
T.krabbei
T. serialis
T. taeniaeformis*
Common Taenid species in canids
Taenia hydatigena
T.pisiformis*
T.ovis
T.krabbei
T. serialis
Diagnosis and clinical signs of taenia spp. In the DH (dog or cat)
Almost always subclinical
Fecal flotation for eggs
Not sensitive (20-30%)(using high specific gravity solution >1.3, or sedimentation)
Not specific- morphological identical to echinococcus
Coproantigen or coporoPCR
Segments or adults cestode in feces or on necropsy (fairly easy to determine genus- usually sent to a specialized lab to determine species)
Control and treatment of Taenia in DH
Animals at risk are any free-roaming pet with access to IH (hunt,scavenge), potentially raw meat diets
Goal: halt environmental contamination with immediately infective, resistant eggs
Several pesticides labelled for dogs and cats that will kill adult tapeworms
Control: prevent access to IH, cook or freeze offal and meat before feeding to dogs
There are no pharmaceutical control measures for intermediate hosts
Remember these will cycle wherever wild hosts are present
Taenia spp. From dogs and cats are not zoonotic
Echinococcus granulosus/E. Canadensis DH and IH
DH: wolves, coyotes, dogs
IH: sheep, moose, elk, caribou, deer (people)
Echinococcus multilocularis DH and IH
DH: fox, coyotes, wolves, dogs (cats)
IH: rodents (dogs, people)
Epidemiology/ecology of E.canadensis
All across canada except NL (so far)
E.canadensis is only species present in canada
11% of dogs in eastern SK reserve community
70% of wolves, 30% of coyotes
Prevalence tends to increase with age
Predator-prey indirect life cycles
Carnivore DH
Herbivore IH
Eggs immediately infective and very resistant
Life cycle of Echinococcus canadensis
Infective egg in feces of DH
Eaten by IH cystic hydatid
Devlops for 6-12 months in IH
IH eaten by DH
PPP~6 weeks
IH of Echinococcus canadensis
Moose>caribou>elk>deer
Cervid IH
Diagnosis and clinical signs of Echinococcus spp, in DH (dog)
Almost invariably subclinical
Fecal flotation for eggs (low sensitivity, 17-27%)
CoproPCR (higher sensitivity, >80%) and can distinguish among Taneia and 2 Echinococcus spp.
Adult cestodes in feces or on necropsy?
Life cycle of Echinococcus canadensis with humans
Humans can eat the infective eggs
Echinococcus multilocularis distribution
All of western Canada now considered endemic (maybe not Vancouver island)
Also in southern Ontario
Prevalence
30-70% in coyotes
30% of foxes
13% of wolves
Echinococcus multilocularis life cycle
Infective eggs in feces
Alveolar echinococcosis develops in IH
Develops in 2-4 months in IH
DH eats IH
PPP 35 days
Echinococcus spp.:larval stages
Cystic hydatid- many protoscolices free in single chambered fluid-filled cyst
Alveolar hydatid- many protoscolices free in multi chambered fluid filled cysts
Diagnosis of canine Alveolar echinococcosis (AE)
Suspicion: medical imaging, liver mass in young dog
Ddx neoplasia, granuloma, other causes of cyst
Suggestive: serology, histopathology
Protoscolices only present in about ⅓ of dogs
Periodic acid-Schiff (PAS) stain to detect membrane
Calcareous corpuscles
Potential for misdiagnosis with other larval cestodes
Definitive: immunohistochemistry, PCR
Abdominocentesis fluid
Aspirated cyst contents
Biopsy, surgical resection
Risk factors for AE
There have been at least 35 cases in dogs across most of Canada since 2009, 6+ in SK, 15+ in AB
Contact with wildlife, esp coyotes and foxes
Habitat overlap
70% of coyotes in a study
European strain E.multi
Use of off leash areas
Copropahgic dog
Management of canine AE
Collect fecal sample for flotation and/or fecal PCR
Treat with adult cestocide (initially)
I.e. praziquantel at 5 mg/kg daily for 2 days
Treat with larval cestocide (long term/life long)
I.e. albendazole (larval cestocide) at 10 mg/kg daily
Surgical debulking/resection if clinically indicated
Advise owner to consult health care provider
Poor prognosis indicators: lare detection, significant abdominal effusion, metastases
Control of Echinococcus in DH (dog)
Goal: halt environmental contamination with immediately infective, highly resistant eggs
Resistant to most chemicals
Killed by heat, drying, and freezing below -80*C
Control: prevent access to IH (freeze or cook off)
Why treat? Primarily public health considerations
With what? Praziquantel- high efficacy against adults
Who and where? High risk dogs in endemic regions
Free-roaming, hunting, scavenging, raw meat
When to treat Echinococcus in DH
High risk: prophylactically, year round, q 4-6 weeks
Known positive (eggs may shed for 3 days post tx)
Advise owner to consult health care provider
Cysticercoid means
single protoscolex, no cyst, in an arthropod
Cyclophyllid cestodes larval stages
Cysticercoid- single protoscolex, no cyst, in an arthropod
Cysticercus- single protoscolex, fluid filled cyst
Coenurus- many (10s) protoscolices attached to wall of fluid flipped cyst
Strobilocercus- single miniature adult, no cyst
Cystic hydatid- many (1000s) protoscolices free in fluid filled cyst
Alveolar hydatid- many (100s) protoscolices free in multi chambered fluid filled cysts
Cystic hydatid is
many (1000s) protoscolices free in fluid filled cyst
Alveolar hydatid is
many (100s) protoscolices free in multi chambered fluid filled cysts
Epidemiology/ecology of Dipylidium
IH is fleas
Present wherever you have fleas
More common on the coasts and further south
35% of shelter cats in Oklahoma: proglottids were detected in 19% of these; all negative on fecal float
Global distribution
Indirect life cycles
Dog or cat definitive host (DH)(rarely humans)
Arthropod intermediate hosts (IH)
Zoonotic but not directly from pets (eat flea)
Life cycle of Dipylidium caninum
Gravid segments and egg packets are passed in feces of DH
Flea larvae with cysticercoid
Adult flea with cysticercoid
IH: fleas
Ingested by dogs
PPP 2-3 weeks
Egg packets of Dipylidium caninum
Each packet contains up to 30 eggs
Each eggs contains a hexacanth larvae
Heavy do not float
Cyclophyllid cestodes: larval stages
Cysticercoid- single protoscolex, no cyst, in an arthropod
Cysticercus- single protoscolex, fluid filled cyst
Coenurus- many (10s) protoscolices attached to wall of fluid flipped cyst
Strobilocercus- single miniature adult, no cyst
Cystic hydatid- many (1000s) protoscolices free in fluid filled cyst
Alveolar hydatid- many (100s) protoscolices free in multi chambered fluid filled cysts
Diagnosis and control of Dipylidium
Diagnosis based on detection of egg packets or segments (most likely) in feces (cucumber seeds)
Several products labelled for dogs an cats
Treat all pets in household
Flea control imperative
Treatment failures generally flea related
Short PPP sometimes makes it look as treatment has failed
Helminths of dogs
Small intestine
Pseudophyllid cestodes (2 IH)
Fish or tapeworms: DH dogs, piscivores, people
Fresh water
Diphyllobothrium latum (walleye, pike, pickerel, perch, burbot)
D. dendriticum ( whitefish, burbot, sticklebacks)
Marine
D. ursi (Pacific salmon)
D. nihonkaiense (Pacific salmon)
Epidemiology/ecology of Diphyllobothrium
1.3% of 231 shelter dogs in Regine
5% of 259 dogs from remote and northern SK
Indirect life cycles
Dog DH (also humans and bears)
Cetacean 1st IH
Fish 2nd IH +/- PH
Zoonotic from eating fish
Life cycle of Diphyllobothrium
Eggs in feces
grow to Coracidum in environment
Curstacean gest infected with procercoids
Fish eats crustacean
IH2 now has plerocercoids
IH2 can be eaten by dog OR
Pisciverous fish PH
PH or IH eaten by DH
PPP 2-4 weeks
adults can live for years
Diagnosis and control of Diphyllobothrium
Diagnosed based on detection of eggs ro segments (long strands of gravid segments) in feces
Little clinical significance (gross factor)
Prevent access to raw fish
Cook or deep freeze fish prior to consumption
Prevent dogs from contaminating water
Intestinal flukes of dogs and cats
Alaria spp. - dogs (common NW Canada)
Nanophyetus salmincola (BC)- dogs (and cats)
Liver flukes of dogs and cats
Metorchus conjunctus- dogs
Are dog and cat flukes zoonotic
All potentially zoonotic, but not directly from pets (humans serve as aberrant DH)
Alaria spp
DH dohs (cats, wild canids, people)
3% of 231 shelter dogs in Regina, 8% of 62 dogs in SE Sk
Zoonotic but not directly from pets
Life cycle of Alaria
Eggs in feces
Miracidium
Snail first IH
cercaria
Tadpole or frog second IH with metacercariae
Can have a small mammal PH
PH or IH eatedn by DH
PPP 1-2 weeks
Nanophyetus salmincola is
DH dogs (cats, people)
Fluke infection is harmless to dog but
Transmits neorickettsia helminthoeca, causes salmon poisoning in dogs in BC< NW USA
Rise of body temp, loss of appetite, vomiting, diarrhea, listlessness and/or rapid weight loss
Treat fluke with praziquantel, rickettsia with doxycycline
Life cycle of Nanophyetus
Eggs in feces
Mircidium
Snail first IH
Cercariae
Salmon fish second IH with metacercariae
DH eats IH
Metorchis conjunctus common in and is it zoonotic
DH dogs (rural, remote and northern)
Cats, fox, mustelids, people
Zoonotic but not directly from dogs
Life cycle of Metorchis conjunctus
Eggs in faeces
Miracidium
Snail first IH
Cercariae
Sucker fish seond IH woth metacercariae
DH eats second IH
Diagnosis and control of trematodes
Diagnosis on detection of eggs in feces (flotation)
Usually subclinical
Prevent access to raw fish/frogs (PH)
Cook or freeze prior to feeding (or eating)
Prevent dogs from fecally contaminating water
