1
ESCCAP Guideline 01 Sixth Edition – May 2021
Worm Control
in Dogs and Cats
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2
ESCCAP
Malvern Hills Science Park, Geraldine Road, Malvern,
Worcestershire, WR14 3SZ, United Kingdom
First Edition Published by ESCCAP in December 2006
© ESCCAP 20062021
All rights reserved
This publication is made available subject to the condition that any redistribution or
reproduction of part or all of the contents in any form or by any means, electronic,
mechanical, photocopying, recording or otherwise is with the prior written
permission of ESCCAP.
This publication may only be distributed in the covers in which it is first published
unless with the prior written permission of ESCCAP.
A catalogue record for this publication is available from the British Library.
ISBN: 978-1-913757-18-2
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ESCCAP Guideline 01 Sixth Edition – May 2021
Worm Control
in Dogs and Cats
1
TABLE OF CONTENTS
INTRODUCTION 6
SCOPE 7
PRESENT SITUATION AND EMERGING THREATS 7
LIFELONG CONTROL OF COMMON WORMS 7
BIOLOGY, DIAGNOSIS AND CONTROL OF WORMS 11
1. Roundworms (Toxocara spp.) 11
2. Tapeworms 13
Echinococcus granulosus and Echinococcus multilocularis 13
Dipylidium caninum 16
Taenia spp. 17
3. Heartworm and Subcutaneous Worms 19
Dirofilaria immitis 19
Dirofilaria repens 20
Zoonotic potential of D. immitis and D. repens 21
4. French Heartworm (Angiostrongylus vasorum) 22
5. Hookworms (Ancylostoma spp. and Uncinaria spp.) 23
6. Whipworm (Trichuris vulpis) 24
DIAGNOSIS OF HELMINTH INFECTIONS 25
IMPACT OF PET HEALTH AND LIFESTYLE FACTORS 26
RESISTANCE TO ANTHELMINTICS 26
ENVIRONMENTAL CONTROL OF PARASITE TRANSMISSION 27
OWNER CONSIDERATIONS IN PREVENTING ZOONOTIC DISEASES 28
STAFF, PET OWNER AND COMMUNITY EDUCATION 29
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FIGURES
Figure 1: Scheme for individual deworming of dogs 9
Figure 2: Scheme for individual deworming of cats 10
Figure 3: Toxocara canis life cycle 11
Figure 4: Toxocara cati life cycle 11
Figure 5: Adult worms live in the small intestine of infected dogs and cats 11
Figure 6: Toxocara cati infective egg 12
Figure 7: Echinococcus granulosus life cycle 13
Figure 8: Echinococcus multilocularis life cycle 13
Figure 9: Approximate summary of distribution of Echinococcus granulosus and related species in Europe 14
Figure 10: Approximate distribution of Echinococcus multilocularis in the fox in Europe 15
Figure 11: Dipylidium caninum life cycle 16
Figure 12: Taenia spp. life cycle 17
Figure 13: Taeniid egg 18
Figure 14: Adult worms live in the pulmonary arteries 19
Figure 15: Dirofilaria immitis life cycle 19
Figure 16: The worm may cause skin nodules and swelling 20
Figure 17: Dirofilaria repens life cycle 20
Figure 18: Approximate distribution of Dirofilaria immitis and Dirofilaria repens in Europe 21
Figure 19: A. vasorum larvae measure approximately 345 μm and 22
are characterised by a wavy tail with a dorsal notch
Figure 20: Angiostrongylus vasorum life cycle 22
Figure 21: Hookworms are small nematodes that live in the intestine of infected dogs and cats 23
Figure 22: Hookworm life cycle 23
Figure 23: Infection can be diagnosed by faecal examination and identification of eggs 24
Figure 24: Trichuris vulpis worm 24
Figure 25: Trichuris vulpis life cycle 24
Figure 26: A heavy infection of Trichuris vulpis in the large intestine of a dog 25
Figure 27: Trichuris vulpis eggs 25
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TABLES
Table 1: Summary of Taenia spp. found in dogs and cats 18
Table 2A: Characteristics of worms of dogs in Europe: intestinal nematodes 30
Table 2B: Characteristics of worms of dogs in Europe: tapeworms (cestodes) 30
Table 2C: Characteristics of worms of dogs in Europe: non-intestinal nematodes 31
Table 3: Risk factors for worms of dogs in Europe 32
Table 4: Characteristics of worms of cats in Europe: nematodes and tapeworms (cestodes) 33
Table 5: Risk factors for worms of cats in Europe 35
Table 6: Worm infection of dogs: main clinical signs and diagnosis 36
Table 7: Worm infection of cats: main clinical signs and diagnosis 38
APPENDIX
APPENDIX 1 – GLOSSARY 40
APPENDIX 2 – BACKGROUND 41
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INTRODUCTION
There is a wide range of helminths including nematodes, cestodes and trematodes that can infect dogs and
cats in Europe. Major groups by location in the host are:
Intestinal worms
Ascarids (Toxocara spp.)
Tapeworms
Hookworms (Ancylostoma and Uncinaria spp.)
Whipworm (Trichuris vulpis)
Non-intestinal worms
Heartworm (Dirofilaria immitis)
Subcutaneous worms (Dirofilaria repens)
French heartworm (Angiostrongylus vasorum)
Lungworms
Eye worms (Thelazia callipaeda)
These groups are further summarised in Tables 2A, 2B and 2C. Factors affecting the importance of these
worms include:
Prevalence
Pathogenicity for the host
Zoonotic potential
A combination of these factors
This guideline aims to give an overview of these worms and their significance and to suggest control measures
for the most important species in order to prevent animal and/or human infection.
For simplicity, the nematodes, cestodes and trematodes mentioned in this guideline will be referred to as
“worms” and therapeutic compounds as “anthelmintics”.
A. vasorum is sometimes referred to as a lungworm and sometimes named ‘the French Heartworm’, which is due to the fact that
the adult worms are located in the circulatory system and not the lungs.
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SCOPE
ESCCAP provides research-based, independent advice. It is the aim of ESCCAP to produce a guideline which
delivers comprehensive information and support to assist both veterinarians and pet owners to successfully
control worm infection in dogs and cats. This guideline concentrates on the most important groups of
companion animal worms, both intestinal and non-intestinal. Other canine and feline parasites are addressed
in other guidelines; these will be referred to, where appropriate, in the text. For more information on the
control of ectoparasites, superficial mycoses, vector-borne diseases and intestinal protozoa see ESCCAP
guidelines at www.esccap.org/guidelines/.
PRESENT SITUATION AND EMERGING THREATS
In Europe, an increase in pet travel plus climatic changes will probably influence the present epidemiological
situation of certain endoparasites or may introduce them into different regions. Rare diseases may rise in
frequency due to increased importation into presently non-endemic areas. Furthermore, within the European
Union, removal of border controls under the Schengen Treaty and implementation of the PETS Travel Scheme
in the United Kingdom have led to easy travel between the various countries within continental Europe and,
except for the UK, there are no or limited customs controls of pet animals moving from one country to another.
Whilst pets travelling with their owners account for the majority of pet movement, a large number of dogs and,
to a lesser extent cats, are now being relocated by welfare organisations from, for example, Mediterranean
countries to private households all over Europe. This is particularly significant as the Mediterranean is an area
where parasites such as Dirofilaria immitis are highly prevalent.
Veterinary medicinal products go through a rigorous testing process prior to their approval by European or
national authorities and each indication for use has to be scientifically justified. Veterinarians are trained in the
appropriate use of these compounds according to current national legislation. Most modern endoparasiticidal
compounds for companion animals can be used prophylactically or therapeutically to control endoparasites.
LIFELONG CONTROL OF COMMON WORMS
Parasite infections should be controlled through endoparasite and ectoparasite management and treatment.
Few parasite infections are strictly age-related; the risk continues as the animal ages and so consideration
should be given to provide each dog and cat with appropriate worm control throughout its lifetime. The
routine treatment and prevention of all worms depends upon legislation in individual countries, veterinary
professionals taking local epidemiological circumstances into account, owner perception and individual risk
assessments i.e. hunting pets, previous lungworm exposure, raw meat diets etc. Deworming practices
should therefore always be on the advice of a veterinary professional. See Figures 1 and 2: Schemes for
individual deworming of dogs and cats.
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Please be advised that:
In countries or regions where routine treatments are not acceptable for legislative or other reasons, regular
faecal examinations are recommended. See specific parasite sections within this guideline for more
tailored treatment and control recommendations.
Feeding commercial diets or cooked food (internal temperature of at least 65°C for 10 minutes) or deep
frozen (at least for one week at -17 to -20°C) will prevent raw meat- transmitted parasite infections (see
Tables 3 and 5).
Dogs and cats should not be allowed access to rodents, carcasses, placentae or aborted foetuses of
cattle or sheep.
Dogs and cats should always be provided with fresh, potable water.
Where a specific worm infection is diagnosed, the infection should be appropriately treated and then preventive
measures put in place. Symptomatic dogs or cats should have a physical examination, including relevant
parasitic diagnostic procedures, and complete history considered as these are crucial for the diagnosis,
treatment and control of parasitic infections.
For healthy dogs and cats, the prevention of worm infection is essential. To simplify preventive measures,
ESCCAP has identified three “key” parasite groups that can cause severe disease, pose a zoonotic risk and
have high prevalence in some or all areas of Europe:
Ascarids (Toxocara spp., Toxascaris leonina) (prevalent in all areas)
Echinococcus spp. (see Figures 9 and 10 for distribution)
Heartworm (Dirofilaria immitis see Figure 18 for distribution; Angiostrongylus vasorum occurs Europe-wide
in endemic spots).
Ascarid infections occur across Europe, whilst the distribution of other infections is geographically related. By
adding Echinococcus spp. and/or D. immitis/A. vasorum control to ascarid control measures, basic control
plans can be produced for dogs and cats anywhere in Europe.
In areas endemic for Echinococcus multilocularis, dogs that may hunt and eat small prey should be treated
monthly with a product effective against this parasite.
In areas endemic for Echinococcus granulosus, dogs with access to offal or livestock carcasses should be
treated with a product effective against this parasite at least every 6 weeks.
In areas endemic for Dirofilaria spp., administration of a monthly preventive or a long-acting injectable
preventive during the vector season is recommended. In areas endemic for Angiostrongylus vasorum,
regular diagnostic controls or monthly anthelmintic treatments against this parasite prevent the onset of
important clinical signs.
In areas where only Toxocara spp. is a concern, deworming at least four times a year is recommended if
dogs and cats are housed outside or have access to the outdoors.
Control of other parasites, such as hookworms, whipworms and lungworms can be added as necessary.
Appropriate anthelmintic treatment for all parasites can be identified and the animals treated at suitable intervals.
Responsible ownership of cats and dogs includes regular health controls with faecal diagnostics and
deworming accompanied by regular testing for efficacy.
More detailed considerations for each of the companion animal parasites can be found in the individual
parasite sections.
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Figure 1: Scheme for individual deworming of dogs
ADDITIONAL TREATMENTS FOR DOGS
Roundworms
Puppies From the age of 2 weeks, then every 14 days up to 2 weeks after weaning and then
monthly treatments up to six months of age.
Pregnant bitches To reduce transmission to the puppies, pregnant females can be given macrocyclic
lactones on the 40th and 55th day of pregnancy or fenbendazole daily from the 40th
day of pregnancy continuing to 2 days postpartum.
Lactating bitches Should be treated concurrently with the first treatment of puppies (see above).
Dogs with increased risk of infection i.e.
those used in sport, competitions, shows
or those kept in kennels etc.
Two treatments: a maximum of 4 weeks before and 2–4 weeks after the event.
For kennels: use planned deworming once a month or examine faecal samples
every four weeks and treat according to findings.
Professional dogs i.e. therapy, rescue
or police dogs
Depending on the risk assessment, use planned deworming once a month or
examine faecal samples once a month and treat according to findings.
Dogs sharing homes with children below
5 years or immunocompromised individuals
Depending on the risk assessment, use planned deworming once
a month or examine faecal samples once a month and treat according to findings.
Tapeworms
Travel or import into/from endemic areas
for Echinococcus spp.
Dogs with a high risk of infection should be treated 4 weeks after starting the
trip, then every 4 weeks until 4 weeks after return. After importation, immediate
examination and treatment is recommended.
Eats raw meat and/or offal, eats prey
or goes hunting
Dogs should be tested every 2–3 months by faecal examination and treated
accordingly to findings or dewormed every 6 weeks.
Flea or chewing lice infestation
(as a vector for Dipylidium)
Once when the infestation is established.
Heartworm (Dirofilaria immitis)*
Dogs living in heartworm endemic areas
(see Fig. 18)
Prophylactic larval treatment with macrocyclic lactones at monthly intervals during
the mosquito season.
Travel or importation to/from endemic
areas for heartworm
No later than 30 days after departure to 30 days after last possible travel date at
monthly intervals.
Deworming practices should always be on the advice of a veterinary professional. Regular coprological examination of faeces,
as suggested in Groups A and B, is a good alternative to standard deworming advice.
If the individual risk of an animal cannot be judged clearly, the animal should be examined or dewormed at least 4 times a year.
Studies have shown that deworming 1–3 times a year does not provide sufficient protection. Deworming every 3 months does
not necessarily eliminate patent infections.
* Detailed information about heartworm infection in dogs and cats can be found in ESCCAP Guideline 5: Control of Vector-Borne
Diseases in Dogs and Cats at www.esccap.org
GROUP B
Treat 4 times
a year against
roundworms or
carry out faecal
examination
GROUP D
Treat monthly against
tapeworms; 4–12
times a year against
roundworms depending
on risk analysis
GROUP C
Treat 4–12 times
a year against
roundworms and
tapeworms depending
on risk analysis
GROUP A
Treat 1–2 times
a year against
roundworms or
carry out faecal
examination
YES
YES
NO
NO
Eats prey animals and/or goes outdoors to hunt without
supervision, has a propensity to eat ‘anything’
Eats snails and slugs and/or raw meat
and/or has access to raw meat/offal
Lives indoors only or goes
outdoors but has no direct contact
with other dogs, parks, sandpits,
playgrounds, snails and slugs, raw
meat or prey animals
Goes outdoors and has direct
contact with parks, sandpits,
playgrounds, and other dogs
Dog lives in a fox tapeworm
(Echinococcus multilocularis)
endemic area, eats prey animals
and/or goes outdoors to hunt
without supervision
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Figure 2: Scheme for individual deworming of cats
ADDITIONAL TREATMENTS FOR CATS
Roundworms
Kittens From 3 weeks of age, then every 2 weeks until weaning and then
monthly treatment until the age of 6 months.
Pregnant queens A single treatment of emodepside spot-on approximately seven
days before expected parturition prevents lactogenic transmission
of Toxocara cati larvae to the kittens.
Lactating queens Should be treated concurrently with the first treatment of kittens
(see above).
Cats with increased risk of infection i.e. those used in
competitions, shows or those kept in catteries etc.
Two treatments: a maximum of 4 weeks before and 2–4 weeks
after the event. For catteries: use planned deworming once a
month or examine faecal samples every four weeks and treat
according to findings.
Cats sharing homes with children below 5 years or
immunocompromised individuals
Depending on the risk assessment, use planned deworming
once a month or examine faecal samples once a month and treat
according to findings.
Tapeworms
Eats raw meat and/or offal, eats prey or goes hunting Cats should be tested at least 4 times a year by faecal
examination and treated accordingly to findings or dewormed
at least 4 times a year.
Flea infestation (as a vector for Dipylidium) Once when the infestation is established.
Echinococcus multilocularis Cats rarely shed E. multilocularis eggs and therefore infection is of
little epidemiological significance.
Heartworm (Dirofilaria immitis)*
Cats living in heartworm endemic areas (see Fig. 18) Prophylactic larval treatment with macrocyclic lactones at monthly
intervals during the mosquito season.
Travel or importation to/from endemic areas for heartworm No later than 30 days after departure to 30 days after last possible
travel date at monthly intervals.
Deworming practices should always be on the advice of a veterinary professional. Regular coprological examination of faeces,
as suggested in Groups A and B, is a good alternative to standard deworming advice.
If the individual risk of an animal cannot be judged clearly, the animal should be examined or dewormed at least 4 times a year.
Studies have shown that deworming 1–3 times a year does not provide sufficient protection. Deworming every 3 months does
not necessarily prevent patent infections.
* Detailed information about heartworm infection in dogs and cats can be found in ESCCAP Guideline 5: Control of Vector-Borne
Diseases in Dogs and Cats at www.esccap.org
Cat lives indoors
Infection pressure with worm stages
is low, eating rodents unlikely
Cat is free to roam
Infection pressure with worm stages
is high, eating rodents likely
RISK GROUP B
To minimise the risk of excretion of Toxocara
and Taenia eggs, carry out faecal examination
(and treatment according to findings) at least
4 times a year or treat against roundworms
and tapeworms* at least 4 times a year
(*Taenia taeniaeformis infections often occur while
cats rarely shed E. multilocularis eggs and infection
has a low epidemiological significance)
RISK GROUP A
1–2 times per year faecal examination
(and treatment according to findings) or treat
1–2 times a year against roundworms
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BIOLOGY, DIAGNOSIS AND CONTROL OF WORMS
1. Roundworms (Toxocara spp.)
Toxocara canis is a large, intestinal nematode, with adults measuring as much as 15 cm in length that
can cause disease in young dogs. Similarly, Toxocara cati, an intestinal nematode with adults measuring up
to 10 cm in length, can cause disease in young cats.
Toxocara spp. infection can occur in puppies and kittens but also in older dogs and cats. Infection of humans
can occur as a result of accidentally ingesting infective eggs or eating undercooked meat containing larvae.
Adult worms inhabit the small intestine (Figure 5)
where they lay eggs that are then passed in the
faeces. The eggs can become infective after several
weeks and these can survive in the environment
for years. Dogs and cats become infected when
they ingest infective eggs from the environment
(Figure 6). Dogs and cats can also become infected
when they eat undercooked meat or prey on an
infected paratenic host (e.g. rodents).
The eggs hatch in the intestine releasing larvae
that penetrate the intestinal wall and undergo a
hepato- tracheal migration, with the life cycle
completed when larvae are coughed up and
swallowed, returning to the small intestine to
complete their migration (Figure 3 and Figure 4).
In puppies, infection can occur by the passage of
larvae across the placenta from about the 42nd day
of pregnancy and later through the milk (Figure 3).
Kittens can be infected through the milk (Figure 4).
Somatic migration can occur in older canines and
felines and non-canid/felid hosts that can then act
as paratenic hosts.
Figure 4: Toxocara cati life cycleFigure 3: Toxocara canis life cycle
Figure 5: Adult worms live in the small intestine of infected
dogs and cats
eggs can survive
in the environment
for years
eggs passed in faeces
humans can be
infected by ingesting
infective eggs
humans can be
infected by ingesting
infective eggs
eggs ingested
by small mammals
eggs passed
in faeces
eggs passed
in faeces
transmission
to kittens
via milk
transmission
to kittens
via milk
cats infected by ingesting
small mammals, infective
eggs or undercooked meat
humans can be
infected by ingesting
infective eggs
humans can be
infected by ingesting
infective eggs
eggs ingested
by small mammals
eggs can survive
in the environment
for years
eggs passed
in faeces
eggs passed
in faeces
eggs passed in faeces
dogs infected by ingesting
infective eggs, small mammals
or undercooked meat
transmission
to pups via
placenta or milk
transmission
to pups via
placenta or milk
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In adult animals, infections are extremely unlikely
to be associated with clinical signs therefore it is
difficult to determine whether a dog is infected unless
regular faecal examinations are conducted. Puppies
can be heavily infected by T. canis worms in utero
or via nursing and these may cause serious illness
before diagnosis is possible by faecal examination.
In addition, these parasites are prolific egg-layers
and just a few worms can produce large numbers of
eggs which are able to survive for a long time in the
environment.
Roundworms have an elevated zoonotic potential.
After oral intake of infective roundworm eggs, the
larvae may begin somatic migration (larva migrans
complex). This can have serious consequences
on human health (see chapter on OWNER
CONSIDERATIONS IN PREVENTING ZOONOTIC
DISEASES). For these reasons Toxocara spp.
infections in dogs and cats of all ages merit
consideration.
Puppies should be treated with appropriate anthelmintics from 14 days old. The treatment should then
be repeated fortnightly until two weeks after weaning and then monthly treatments carried out up to six
months of age.
Because prenatal infection does not occur in kittens, fortnightly treatment can begin at 3 weeks of age
and be repeated fortnightly until two weeks after weaning, then monthly treatments carried out up to six
months of age.
To reduce transmission to the puppies, pregnant bitches can be given macrocyclic lactones on the 40th
and 55th day of pregnancy, or fenbendazole daily from the 40th day of pregnancy continuing to 2 days
postpartum.
Pregnant queens should be treated with emodepside spot-on approximately seven days before expected
parturition to prevent lactogenic transmission of Toxocara cati larvae to the kittens.
Nursing bitches and queens should be treated concurrently with the first treatment of their offspring, as
they often develop patent infections at this time.
For adult dogs and cats, ESCCAP recommends an individual risk assessment for each animal to determine
whether anthelmintic treatment is necessary, and how often. There is surprisingly little information about
the impact of re-treatment intervals on parasite burdens and environmental contamination on which to
base a maximum re-treatment interval under different epidemiological conditions. Current information
suggests that annual or twice yearly treatments do not have a significant impact on preventing patent
infection within a population. Therefore, a treatment frequency of at least 4 times per year is a general
recommendation.
As the pre-patent period for Toxocara spp. after ingestion of larvae via predation of paratenic hosts
(rodents) or infective eggs from the environment is a little over four weeks, monthly treatment will minimise
the risk of patent infections and is recommended in risk scenarios, for example when the pet shares a
house with small children and has frequent risk of infection (free roaming, access to garden).
As an alternative to repeated treatments, faecal examinations can be performed at suitable intervals followed
by anthelmintic treatment where positive results are found (see chapter on DIAGNOSIS OF HELMINTH
INFECTIONS). This approach should be adopted in countries where routine treatments are not acceptable
for legislative reasons. Nevertheless, between faecal examinations the excretion of infective eggs is still
possible and cannot be prevented. Caution must be taken in cases of negative results following faecal
examination: it cannot be assumed with certitude that an animal is not infected with roundworms in case
of prepatent infections or when the number of excreted eggs is under the detection limit of the analysis.
For further information on Toxocara spp. characteristics, risk factors, clinical signs, diagnosis and treatments
see Tables 2A and 3–7.
Figure 6: Toxocara cati infective egg
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2. Tapeworms
Echinococcus granulosus and Echinococcus multilocularis
Echinococcus granulosus (dog tapeworm) is a small cestode that inhabits the small intestine of dogs and
some other canids, excluding foxes. Echinococcus multilocularis (fox tapeworm) is a small cestode that
inhabits the small intestine of foxes, raccoon dogs, some other canids and rarely dogs and very seldom cats.
See Figures 7 and 8 for life cycles.
Both the tapeworms, E. granulosus and E. multilocularis induce extra-intestinal metacestode stages in
intermediate hosts and both are zoonoses of major public health concern. In humans, E. granulosus causes
cystic echinococcosis and E. multilocularis causes alveolar echinococcosis, which if untreated can have
potentially fatal consequences. Both infections result in the formation of cysts, most commonly in the liver
(E. multilocularis, E. granulosus) or in the lung (E. granulosus). These occur following the oral ingestion of eggs
or proglottids excreted in the faeces of the definitive hosts. They are immediately infective to intermediate
hosts including humans.
Figure 8: Echinococcus multilocularis life cycle
Figure 7: Echinococcus granulosus life cycle
DEFINITIVE HOSTS
ingest infected rodents
eggs passed in
faeces into the
environment
eggs passed in
faeces into the
environment
humans can be infected
by contaminated food
humans can
ingest eggs by
hand-to-mouth
contact with
dog faeces
humans can
ingest eggs by
hand-to-mouth
contact with
dog faeces
INTERMEDIATE HOSTS
ABERRANT HOSTS
ingest eggs from the environment
eggs contain
oncospheres
alveolar
hydatid
cyst
DEFINITIVE HOST
ingests raw
offal containing
hydatid cysts
eggs passed in
faeces into the
environment
eggs passed in
faeces into the
environment
humans can ingest eggs by
hand-to-mouth contact with
dog faeces or direct contact
with dog and/or can be
infected by ingestion of eggs
from the environment
INTERMEDIATE HOSTS
ABERRANT HOST
ingest eggs from the environment
eggs contain
oncospheres
hydatid cysts develop
from oncospheres
14
In the central and Eastern European endemic area of E. multilocularis (Figure 10) with red foxes as main
definitive hosts and voles as intermediate hosts, dogs that have access to rodents should also be treated at
four weekly intervals with an effective anthelmintic containing praziquantel or epsiprantel. Cats, in contrast to
dogs, are epidemiologically insignificant as sources of egg output. Whilst in dogs, it is common to find eggs
in the fur of infected animals, no eggs have been recovered to date from the coat of infected cats and their
zoonotic potential is also probably limited because there is only a small risk of cats excreting large numbers
of eggs. Specific diagnosis of Echinococcus infections in definitive hosts is difficult as taeniid eggs (including
Echinococcus spp. and Taenia spp.) cannot be differentiated morphologically and are passed intermittently.
Figure 9: Approximate summary of distribution of Echinococcus granulosus and related species in Europe (© ESCCAP)
In areas where E. granulosus and related species are endemic (Figure 9), care should be taken to prevent dogs
having access to raw offal and carcasses. Where dogs may have access to carcasses or raw viscera especially
from sheep, pigs, cattle or horses (depending on the Echinococcus genotypes present locally) they should be
treated at least every six weeks with an effective anthelmintic containing praziquantel or epsiprantel.
Echinococcus granulosus
Sheep strain – high prevalence
Pig strain – high prevalence
15
Figure 10: Approximate distribution of Echinococcus multilocularis in the fox in Europe (© ESCCAP)
DNA-based tests for species and/or genotype identification are only performed in specialised laboratories.
Therefore in Echinococcus endemic areas, taeniid infections based on egg detection should be handled
as potential Echinococcus infections since eggs are directly infective. Where animals are infected with
an Echinococcus species, it is advisable that they are treated under the supervision of a veterinarian with
praziquantel or epsiprantel on two consecutive days, and that the dogs are shampooed to remove any
parasite eggs adhering to the coat. The faeces of treated dogs should be appropriately eliminated (in waste
that will be burned) up to three days after anthelmintic treatment. The personnel involved should use suitable
protective clothing such as gloves and a mask.
E. multilocularis
16
Prevention is achieved through the following recommendations:
If possible, dogs should not have access to wild rodents.
Dogs and cats should not be given slaughter waste or raw meat but only commercial food or meat that has
been heated for 10 minutes (inner temperature: 65°C) or frozen for one week at -17 to -20°C.
For dogs with a high risk of infection with Echinococcus spp., ESCCAP promotes monthly treatments with
an appropriate anthelmintic containing praziquantel or epsiprantel.
Dogs travelling into areas with a high risk of Echinococcus spp. infections should be treated four weeks
after starting the trip and for four weeks after returning with an appropriate anthelmintic containing
praziquantel or epsiprantel.
Dogs imported from endemic areas should be promptly seen by a veterinarian and treated with an
appropriate anthelmintic containing praziquantel or epsiprantel.
Cats are comparatively unsuitable hosts for E. multilocularis. Even in infected cases, cats only excrete
a low number of eggs which have not shown to be infective under experimental conditions, therefore
representing a fractional risk. However, as a precaution, cats with excretion of taeniid eggs should be
treated appropriately.
For further information on Echinococcus spp. characteristics, risk factors, clinical signs, diagnosis and
treatments see Tables 2B and 3–7.
Dipylidium caninum
Dipylidium caninum is a tapeworm of dogs and cats. The parasite is common throughout Europe.
The intermediate hosts are the flea or the chewing dog louse and dogs and cats become infected when
they ingest the infected insects. The adult tapeworm develops within the dog or cat in the small intestine
(Figure 11). D. caninum is zoonotic and if humans ingest infected fleas or lice they can become infected,
although this is rare. The prepatent period is approximately three weeks.
Figure 11: Dipylidium caninum life cycle
dogs and cats
ingest infected
fleas or lice
dogs and cats
ingest infected
fleas or lice humans can ingest
infected fleas or lice
humans can ingest
infected fleas or lice
adult tapeworm develops
in the dog or cat
adult tapeworm develops
in the dog or cat
proglottids
passed in faeces
egg packets
containing
oncospheres
released
oncospheres ingested by
developing flea larvae or lice
infected larvae
develop into adult
fleas or lice
fleas or chewing lice
INTERMEDIATE HOSTS
17
Infection with D. caninum is rarely associated with clinical signs in dogs and cats. The mature segments
leaving the anus may result in anal irritation (pruritus) causing an animal to rub its bottom along the ground.
The white proglottids may be seen in fresh faeces or in the coat around the anus. When dry, these are shaped
like rice grains and may be evident around the perianal area and in samples from the animal’s bedding.
Treatment is performed with praziquantel or epsiprantel and control management is achieved by additional
control of fleas and lice.
For further information on D. caninum characteristics, risk factors, clinical signs, diagnosis and treatments
see Tables 2B and 3–7.
Taenia spp.
Taenia spp. are tapeworms that can infect dogs, cats and foxes by the ingestion of intermediate hosts. They
are common throughout Europe.
Dogs and cats become infected when they eat the tissue or viscera of infected intermediate hosts. Infection
of the intermediate host occurs by ingestion of tapeworm eggs in proglottids passed in the faeces of the
definitive host (Figure 12). The effects on the intermediate host may be more profound than on the definitive
host. The intermediate hosts are varied and, depending on the Taenia spp., range from sheep and cattle
(Taenia multiceps) to rabbits (Taenia serialis, Taenia pisiformis), rodents (Taenia taeniaeformis), ruminants and
pigs (Taenia hydatigena) and sheep and goats (Taenia ovis) (Table 1).
The prepatent period for Taenia spp. ranges from about four to ten weeks in dogs (depending on the species)
and is approximately five to ten weeks for T. taeniaeformis in cats, which uses rodents as intermediate hosts.
Patency can last for several months up to several years, for example T. ovis, a Taenia species infecting dogs,
can be patent for up to five years.
Taenia spp. infections are rarely associated with clinical signs in dogs or cats. The mature segments leaving
the anus may result in anal pruritus causing an animal to rub its bottom along the ground. Owners may also
notice motile segments crawling on the animal’s coat after leaving the anus.
Figure 12: Taenia spp. life cycle
infected by ingesting
eggs or proglottids
oncospheres circulate to tissues
in intermediate hosts
humans
infected by
ingesting
embryonated
eggs
embryonated egg
proglottids
containing infective
eggs passed in faeces
adult worms
develop in the
small intestine
INTERMEDIATE HOSTS
infected
by ingesting
intermediate
hosts
HOSTS
18
Taeniid eggs (Figure 13) may be detected upon
faecal examination. Taenia spp. eggs cannot be
differentiated microscopically from Echinococcus
eggs. Therefore in Echinococcus endemic areas,
taeniid infections based on egg detection should be
considered as a potential Echinococcus infection.
Macroscopic examination of the faeces may
demonstrate the presence of white proglottids;
microscopically, unlike D. caninum each has only
one genital pore.
Treatment is by the administration of an effective
anthelmintic at suitable intervals which will most
likely depend upon evidence of an existing infection.
Eggs can remain viable for lengthy periods in the
environment. Owners should try and prevent dogs
and cats having access to the various intermediate
hosts. The feeding of raw meat and viscera should
be discouraged.
Table 1: Summary of Taenia spp. found in dogs and cats
Definitive
hosts DOGS CATS
Species Taenia
multiceps
Taenia serialis Taenia
crassiceps*
Taenia
pisiformis
Taenia
hydatigena
Taenia
ovis
Taenia
taeniaeformis
Prepatent
period (approx.
in weeks)
6 4–6 6–8 7–10 6–8 5–10
Intermediate
host
Sheep, goats
and cattle
Rabbits
(and rodents) Rodents Rabbits/hares
(and rodents)
Sheep, goats,
cattle and pigs
Sheep
and goats Rodents
Intermediate
stage and site
Coenurus
larvae in brain
and spinal
cord
Coenurus
larvae in
connective
tissue
Cysticercus
larvae in body
cavities or
subcutaneous
tissue
Cysticercus
larvae in
abdomen
or liver
Cysticercus
larvae in
abdomen
or liver
Cysticercus
larvae in
muscles
Strobilocercus
larvae in liver
and abdomen
* much more frequently found in red foxes
For further information on Taenia spp. characteristics, risk factors, clinical signs, diagnosis and treatments
see Tables 2B and 3–7.
Figure 13: Taeniid egg
19
3. Heartworm and Subcutaneous Worms
Dirofilaria immitis
Dirofilaria immitis is a filarial worm that resides in
pulmonary arteries of dogs and cats (Figure 14). Also
known as heartworm, it is transmitted by intermediate
mosquito hosts (Figure 15). Heartworm infection
(D. immitis) is endemic in many southern and south-
eastern European countries (Figure 18). Climatic
changes favourable to parasite development and the
increasing number of travelling pets have increased
the risk of infection for dogs, cats and pet ferrets.
Although cats are potential hosts for heartworm,
their relevance as definitive hosts is clearly reduced
compared to dogs.
Infection with D. immitis may cause severe and
potentially fatal disease in dogs and cats. Low
worm burdens can be asymptomatic. Increasing
worm burdens can cause clinical signs such as loss
of condition, weakness, dyspnoea and chronic
cough. If untreated, the disease can progress to right
side heart failure and death. In cats, the disease is
mostly asymptomatic but in rare cases may cause
sudden death.
In most parts of Europe where infection is endemic,
the transmission season of heartworm lasts from
April to October (depending on the climate). Yearlong
transmission of D. immitis is only actually reported
for the Canary Islands (Spain).
In dogs and cats, control depends upon the use
of heartworm preventive treatments (macrocyclic
lactones) that kill the juvenile heartworm stages prior
to their migration towards the pulmonary artery and
right side of the heart. Infection cannot be hindered,
but the use of appropriate products can effectively
prevent development into adult heartworm and the
onset of clinical signs of infection.
The combination of heartworm preventatives with repellents/insecticides designed to prevent mosquito
blood-feeding activity during the heartworm transmission season could be useful in protecting dogs from
infection. Recently, topical administration of permethrin with dinotefuran has shown repellent efficacy against
mosquitoes on dogs for at least 4 weeks.
In endemic areas, puppies and kittens need to be placed on preventive heartworm treatment as soon as
possible after birth (consistent with label recommendations). Most preventive anthelmintics effective against
heartworm also control a range of other worms, therefore a product should be chosen to control all relevant
worms. In addition, treatment can be extended throughout the year to ensure the continued control of non-
seasonal parasites such as Echinococcus spp. and Toxocara spp., where necessary. The use of such products
should commence within the first four weeks after the start of a potential transmission and maintained monthly
until 30 days after the last potential date of an infection. As a principle, all dogs previously exposed to the risk
of D. immitis infection should receive a complete clinical check-up, including blood tests to detect microfilariae
and/or serology to detect circulating antigens or antibodies for the diagnosis of heartworm infections.
Detailed information about heartworm infection in dogs and cats can be found in ESCCAP Guideline 5:
Control of Vector-Borne Diseases in Dogs and Cats at www.esccap.org
Figure 14: Adult worms live in the pulmonary arteries
Figure 15: Dirofilaria immitis life cycle
humans can also
become infected
humans can also
become infected
adult parasites
sexually reproduce in the
vertebrate host
adult parasites
sexually reproduce in the
vertebrate host
mosquito feeds
and infective larvae
enter the host
mosquito feeds
and microfilariae
are ingested
third stage
larvae migrate
to proboscis
of mosquito
third stage
larvae migrate
to proboscis
of mosquito
larvae develop
inside the mosquito
larvae develop
inside the mosquito