Parasite control programs for dogs and cats 3 Flashcards
Which intestinal parasites in dogs/cats require preventive treatment?
- Roundworms
- Hookworms
- Whipworms?
- Tapeworms?
Toxocara canis life cycle, transmission routes
- adult worms lay eggs in small intestine
- eggs passed in feces > not immediately infective, need a few weeks in environment
- eggs embryonate
- embryonated eggs in feces, ingested by dog or intermediate host
- if ingested by intermediate host, tissue of intermediate host ingested by dog…
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Four transmission routes: - transplacental
- transmammary
- direct ingestion of embryonated egg
- ingestion of infected intermediate host
at what age will puppies shed eggs in feces, if infected with toxocara canis?
eggs in feces by 3 weeks of age
Toxocara canis in bitch - transmission to puppies? relevance?
- Parasites accumulate in tissues over entire life
- Tissue parasites reactivated ~3 weeks before whelping:
> uterus > fetuses
> mammary gland > milk
> intestine > eggs in feces
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treat the mother at the same time as puppies!!!
Toxocara canis
Prevalence:
- ~ 4% dogs overall in southern Ontario
- higher in dogs < 6 months of age (e.g. 14% in Niagara pups)
- in adult dogs - more common in lactating bitches
- strays > well cared for dogs
Toxocara canis
Clinical signs:
- subclinical infections are common
- emaciation, rough hair coat
- mucoid diarrhea, vomiting (+/-parasites)
- abdominal distension
- clinical disease most severe in young pups
Toxocara cati life cycle? transmission routes?
- eggs passed in feces
- eggs embryonate
- emryonated eggs in feces ingested by cat or intermediate host
- if egg ingested by intermediate host, intermediate host now ingested by cat…
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Three transmission routes: - transmammary (minor for this parasite)
- ingestion of embyonated egg
- ingestion of infected intermediate host
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NOTE: No transplacental!!
at what age do we see toxocara cati eggs in the feces of infected kittens?
eggs in feces by 4-5 weeks of age
Toxocara cati
- prevalence
- age for patent infections from transmamamry route
- ~5% cats overall in southern Ontario
- higher prevalence in kittens + feral cats
(e.g. 12% in Niagara kittens) - transmammary infection considered a minor route of infection in kittens:
> patent infections by ~4-5 weeks
Toxocara cati
Clinical signs:
- similar to T. canis, but less severe
- subclinical infections = common
- unthriftiness
- intermittent diarrhea, vomiting (+/- parasites)
- abdominal distension
Human toxocarosis - conditions caused by T. canis and cati, transmission
- prevalence
T. canis – most common cause of “Visceral Larva Migrans” and “Ocular Larva Migrans”
T. cati – also zoonotic
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Infection > ingestion of infective eggs (after the eggs have been in the environment for a few weeks!)
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* Current incidence in people in Ontario <1/year, i.e. less than 0.25% of risk quoted for USA
* Not considered an issue by Ontario Public Health experts
Visceral larva migrans - who gets this? risks?
Visceral larva migrans
* most cases children < 4 years old
* increased risk of infection > pups in home +
pica/poor hygiene
Ocular larva migrans - who gets this? risks?
- mean age = children 7-8 years old
- rarely history of pica
Control environmental contamination with Toxocara eggs
- Minimise risk of Toxocara infections in dogs/cats (primary reason for intestinal parasite control)
- Prevent fouling of yards and public places
- Educate public about zoonotic potential of T. canis/T. cati
Ancylostoma caninum life cycle, transmission routes?
- adult worms lay eggs in small intestine
- eggs passed in feces
- eggs hatch and develop into infective larve
- larvae penetrate skin or are ingested by dog
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Three transmission routes: - transmammary
- skin penetration by larvae
- ingestion of larvae
Ancylostoma caninum
- mostly affects who?
- clinical signs?
- prevalence and resistance?
- primarily pathogenic in juvenile dogs
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Clinical signs: - anemia, weakness > sudden death in young pups
- tarry/malenic feces
- very rarely clinical in Ontario
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Chronic disease: - subclinical + anemia
<><><><> - Note: Higher prevalence and burden of hookworms in dogs & cats in southern USA
- 2024: Drug resistance in A. caninum widespread across USA
Hookworm problem in pups (typically not in Canada) - observations? how to treat?
- subsequent litters from same bitch are likely to have the same problem
- treat every 2 weeks from 2 weeks of age until ~10 weeks old
- conservative T. canis prevention should control hookworms
are hookworms in ontario a zoonotic concern?
No evidence hookworms in Ontario are a zoonotic concern
Trichuris vulpis
- nature of infections
- signs
- who gets this? risks?
- prevention?
- most infections = light and subclinical
- if clinical: large bowel diarrhea - hematochezia, mucus, straining
- older dogs tend to have higher burdens than young dogs
- more common in kennel environment
- prepatent period = 10-12 weeks:
> need for routine preventive treatment in young dogs (i.e. < 6 months of age) is questionable
> mature outdoor dogs require a prevention program
Tapeworm diagnosis usually made how? which one is tricky?
signs?
- infections most likely to be diagnosed by finding segments in feces or attached to perianal fur
> segments of E. multilocularis = too small to be visible - typically no clinical signs
- perianal pruritus dragging anus on ground
Dog/Cat tapeworms in Ontario
- Dipylidium caninum (dogs + cats) (flea tapeworm)
- Taenia pisiformis (dogs) (rabbit tapeworm)
- Taenia taeniaeformis (cats) (rats, rodents)
- Echinococcus multilocularis (dogs + cats)
tapeworm therapeutic treatment
- praziquantel (treats all 4 common tapeworms) - one treatment kills adult and immature stages
- epsiprantel (not for Echinococcus) – two treatments may be required
Dipylidium caninum
- life cycle
- prevention
- adult worms in small intestine
- posterior segments of adult worms passed in feces
- segments and egg packets in feces and on fur
- eggs ingested by larval flea
- larval flea develops into adult flea
- infected adult flea ingested by dog
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Prevention: flea control!
Taenia taeniaeformis, Taenia pisiformis
- life cycle, prevention
- adult worms in small intestine
- posterior segments of adult worms passed in feces
- eggs released from segments > eggs in feces
- eggs ingested by intermediate host
- tissues of intermediate host ingested by dog or cat
<><> - Taenia taeniaeformis: IH is rat
- Taenia pisiformis: IH is rabbit
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Prevention: - stop hunting!
- preventative treatment with praziquantel can be done
Tapeworms in Ontario
Is preventive treatment justifiable ?
- individual animal decision:
<><> - cats that eat rodents (T. taeniaeformis):
- treat 1-4 times/year with praziquantel or epsiprantel
<><> - dogs (cats) that eat rodents (E. multilocularis) and live in high risk household:
- treat monthly with praziquantel?
> theoretically this could be done but theres a BIG concern of inducing resistance, so 3 months is better
Puppies and kittens aged 0-6 months
- In southern Ontario, what internal parasites require a preventive program in (a) puppies ? (b) kittens ?
roundworms, hookwroms
At what age should puppies/kittens receive their first preventive treatment with an anthelmintic compound ? Why ?
- by two weeks as this is when we may start to see shedding from young
- (2w is the pre-patent period for hookworms, usually 5w okay for kittens but 2w keeps things simple)
- For puppies in Ontario, what drug would you recommend for the first treatment ? Why ?
- Why should additional treatments be given ?
o Pyrantel, Fenbendazole
> both approved to 0d old
o Milbemycin approved to 2w old, activity against heartworm too (used commonly in USA)
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Additional treatments beyond the first treatment at 2 weeks of age are required because of:
o Reinfection (multiple routes)
o Drugs typically only kill adult nematodes and do not address immature parasites
Intestinal parasite control in puppies & kittens
(a) Puppies:
Deworm at 2, 4, 6, 8, 10, 12 weeks of age
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(b) Kittens:
Deworm at 2, 4, 6, 8, 10, 12 weeks of age
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(a)+(b) Then deworm monthly to 6 months of age
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Ideally, fecal examination at time of 12-week treatment & at 6 months > ensure drugs are working
Intestinal parasite control in puppies & kittens
- What should you recommend when first seen at 7-8 weeks of age?
deworm at 8w, 10w, 12w, 5mo, 6mo!
Companion Animal Parasite Council (USA)
- Dogs & cats > 6 months reccomendations?
- vs Canada?
“Administer year-round treatment with broad- spectrum heartworm anthelmintics that have activity against parasites with zoonotic potential.”
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* Appropriate in southern USA
* Clinical parasitologists at all 5 Canadian veterinary colleges do not believe this is appropriate for Canada
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Canada:
A benefit/risk assessment for each animal should determine the required spectrum of anthelmintic activity, choice of anthelmintic and frequency of administration.
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reasonable parasite control shcedule in canada:
- deworm preventively + monitor:
- high risk household: deworm 3-4 times a year if not on heartworm prevention
- note: animals on most heartworm preventives are dewormed a minimum of 6 times/year
- deworm as indicated by fecal examination (e.g. low-risk household)
Intestinal parasite control in dogs & cats
Nursing bitches/queens reccomendations:
- deworm concurrently with pups/kittens
- no treatment available to eliminate somatic larvae of Toxocara or Ancylostoma
- ivermectin or fenbendazole before/after whelping will reduce transmission of Toxocara / Ancylostoma (note: very rarely used)
