From Dog
Adult hirudinid leech removed from the nasal cavity of a dog
The common flea tapeworm of cats, Dipylidium caninum
Trichuris spp - adult whipworms
Post-mortem specimen from a dog which died suddenly from D. immitis infection
Ctenocephalides canis - the dog flea
Adult Heterodoxus spiniger - dog biting louse
Egg of Toxocara canis under light microscopy, showing the characteristic pitted-edge surface[1]
Giardia spp parasite, a common cause of diarrhoea in cats

The term parasitism may be defined as a two-species association in which one species, the parasite, lives on or in a second species, the host, for a significant period of its life and obtains nourishment from it. This is a commonly accepted working definition of parasitism and using it we can emphasize several important features of the host-parasite relationship. Parasitism always involves two species, the parasite and the host. Many of these parasitic associations produce pathological changes in hosts that may result in disease. Successful treatment and control of parasitic diseases requires not only comprehensive information about the parasite itself but also a good understanding of the nature of parasites' interactions with their hosts. The parasite is always the beneficiary and the host is always the provider in any host-parasite relationship[2].

This definition of parasitism is a general one but it tells us nothing about parasites themselves. It does not address which particular infectious organisms of domestic animals we might include in the realm of parasitology. The protozoa, arthropods and helminths are traditionally defined as parasites. However, there are members of the scientific community who designate all infectious agents of animals as parasites including viruses, protozoa, bacteria and fungi as well as the arthropods, helminths and protozoa. Within this broad definition, parasites are further divided into microparasites and macroparasites.

Various nematodes transmits nematophagous fungal symbionts, Pochonia chlamydosporia[3] and Paecilomyces lilacinus[4] and control of these fungi affects survival and reproductive performance of the nematode[5].

Similarly, the hematophagous nematode Dirofilaria immitis transmits the endosymbiont alphaproteobacteria Wolbachia spp, which affects both its survival, growth and reporuction, and their importance cannot be overemphasized.

In low socioeconomic regions of the world, co-infections with ecto-, endo- and hemo-parasites is extremely common[6].

Common canine parasites


Cuterebra emasculator, Cochliomyia spp, Phortica variegata, Hippobosca longipennis
Aedes spp, Anopheles spp, Culex spp, Culiseta spp, Coquillettidia richiardii, Ochlerotatus taeniorhynchus, Psorophora columbiae, Uranotaenia unguiculata
Cediopsylla simplex, Ctenocephalides spp, Echidnophaga gallinacea, Odontopsyllus multispinosus, Orchopeas howardi, Oropsylla hirsuta, Polygenis gwyni, Pulex irritans, Spilopsyllus cuniculi, Synosternus pallidus, Xenopsylla cheopis
Ixodes holocyclus, Rhipicephalus sanguineus, Amblyomma americanum, Dermacentor andersoni, Haemaphysalis concinna, Ornithodoros talaje, Otobius lagophilus, Hyalomma spp
Demodex spp, Notoedres spp, Eutrombicula alfreddugesi, Neotrombicula autumnalis, Otodectes spp, Cheyletiella spp, Straelensia cynotis, Sarcoptes spp, Dermanyssus spp, Notoedres spp
Heterodoxus spiniger, Trichodectes canis, Linognathus setosus
Onchocerca lupi, Dirofilaria repens, Dracunculus insignis, Dipetalonema reconditum, Cercopithifilaria spp, Schistosoma spp, Acanthocheilonema spp, Microfilaria auquieri, Crenosoma vulpis, Anatrichosoma cutaneum, Pelodera strongyloides


Thelazia spp
Toxoplasma spp, Cuterebra spp, Toxocara canis, Trypanosoma cruzi


Linguatula serrata
  • Leech
Myxobdella annandalei
Pneumonyssoides caninum


Dirofilaria immitis, Brugia malayi, Acanthocheilonema spp, Dipetalonema repens, Microfilaria auquieri
Babesia canis, Theileria annae, Leishmania spp, Trypanosoma spp, Hepatozoon spp, Rangelia vitalii
Anaplasma spp, Bartonella spp, Rickettsia spp, Ehrlichia spp, Mycoplasma spp


Toxocara cati, Dirofilaria immitis
Toxoplasma spp, Balamuthia mandrillaris
Cuterebra emasculator


Dirofilaria spp, Strongyloides spp, Filaroides osleri, Angiostrongylus vasorum, Eucoleus aerophilus, Crenosoma vulpis, Aelurostrongylus abstrusus, Paragonimus spp, Lagochilascaris spp


Dirofilaria immitis, Angiostrongylus vasorum, Crenosoma vulpis


Metorchis bilis, Parametorchis complexus, Clonorchis sinensis, Opisthorchis spp, Metagonimus yokogawai

Reproductive tract

Brucella canis


Dioctophyme renale, Pearsonema plica
Schistosoma japonicum


Dipetalonema reconditum, Cuterebra spp
Dirofilaria immitis
Parametorchis complexus
Trichinella spiralis
Hepatozoon spp, Neospora spp


Linguatula serrata


Physaloptera spp, Spirocerca lupi, Gnathostoma spp, Protospirura spp

Small intestine

Giardia spp, Cryptosporidium spp, Isospora spp, Acanthamoeba spp, Blastocystis hominis, Toxoplasma gondii, Hammondia hammondi, Sarcocystis spp, Neospora spp, Eimeria spp, Balantidium coli, Pentatrichomonas hominis, Tritrichomonas spp, Cystoisospora spp, Entamoeba histolytica, Chilomastix mesnili
Strongyloides spp, Alaria marcianae, Ancylostoma braziliense, Toxocara canis, Uncinaria stenocephala, Toxascaris leonina, Toxocara cati, Trichinella spp
Heterobilharzia americana, Alaria spp, Nanophyetus salmincola, Metagonimus yokogawai, Haplorchis spp, Stellantchasmus spp, Stictodora spp, Centrocestus spp, Cryptocotyle lingua, Apophallus donicum, Acanthotrema felis, Mesostephanus appendiculatum, Echinochasmus schwartzi, Heterophyes heterophyes, Pygidiopsis genata, Prohemistomum vivax, Schistosoma japonicum
Mesocestoides spp, Diphyllobothrium latum, Echinococcus multilocularis, Mesocestoides lineatus, Taenia hydatigena, Dipylidium caninum, Spirometra mansonoides, Diphyllobothrium latum, Joyeuxiella spp, Diplopylidium acanthotetra
Oncicola canis, Macracanthorhynchus ingens

Large intestine

Balantidium coli, Blastocystis spp
Strongyloides spp, Trichuris vulpis


  1. Buckelew
  2. University of Pennsylvania
  3. Araujo JM et al' (2012) Survival of Pochonia chlamydosporia in the gastrointestinal tract of experimentally treated dogs. Res Vet Sci 93(2):803-806
  4. Carvalho RO et al (2010) Ovicidal activity of Pochonia chlamydosporia and Paecilomyces lilacinus on Toxocara canis eggs. Vet Parasitol 169(1-2):123-127
  5. Frassy LN et al (2010) Destruction of Toxocara canis eggs by the nematophagous fungus Pochonia chlamydosporia. Rev Soc Bras Med Trop 43(1):102-104
  6. Bwalya EC et al (2011) Prevalence of canine gastrointestinal helminths in urban Lusaka and rural Katete Districts of Zambia. Prev Vet Med 100(3-4):252-255