Parasite and tick identification in cats and dogs

What it shows

Two lines on the form cover the same idea: the parasite itself is sent to the lab, and a specialist names it. Parasite identification is used for intact internal or external parasites — roundworms, tapeworms or their segments, fleas. Tick identification names the tick removed from the animal, often down to genus and species.

For tapeworms the shape of a segment helps. Segments of Dipylidium caninum look like cucumber seeds with a pore on each side; Taenia segments are rectangular with a single pore; adult Echinococcus worms are tiny, a few millimetres long with only a few segments. Adult ticks are fairly easy to identify; larvae and nymphs are harder, which is why they are best sent to a diagnostic laboratory.

Higher than reference — what it may be a sign of

• The species of tick tells the vet which infections to think about, because many pathogens are carried only by particular ticks. In North America, Ixodes ticks carry the Lyme disease bacterium and Anaplasma phagocytophilum; the brown dog tick (Rhipicephalus sanguineus) carries Ehrlichia canis, Babesia, Anaplasma platys and Hepatozoon canis; the lone star tick (Amblyomma americanum) carries Ehrlichia ewingii and the cat parasite Cytauxzoon felis; Dermacentor ticks carry Rocky Mountain spotted fever. In Europe and other regions the list is different.
• A named tick is not a diagnosis. It shows possible exposure. Transmission takes time after the tick attaches: Ehrlichia and Rickettsia within 3–6 hours, the Lyme bacterium after 24–48 hours of feeding.
• A named tapeworm points to its source: Dipylidium comes from swallowed fleas; Echinococcus matters for people’s health too, because people can be infected by swallowing eggs passed in dog faeces.

Lower than reference

Sometimes the specimen cannot be named — it is crushed, dried, incomplete or an immature stage. And not seeing worms does not mean there are none: roundworms, hookworms and whipworms usually shed microscopic eggs that an owner cannot see, so a stool sample is still worth checking. Fecal flotation is unreliable for tapeworms, and under the microscope the eggs of Taenia and Echinococcus look the same — telling them apart needs PCR.

Look at together with

• Tests for tick-borne infections — Lyme disease, Ehrlichia, Anaplasma, Babesia — the vet chooses them by the tick species, the region and the signs.
• Fecal flotation or a fecal parasite PCR panel — look for the eggs or DNA of parasites that cannot be seen by eye.
• Skin parasites — fleas found during the visit are part of the same picture as Dipylidium.

Units and conversion

There are no units and nothing to convert. The result is a name: the genus and, where possible, the species of the parasite or tick, sometimes with its life stage (larva, nymph, adult). In the app the result is stored as text.

Reference range

The reference range is on your lab’s form — but for this test it is not a number. The answer is simply what the specimen is. The specimen goes intact into a leak-proof tube or container; for worms, fleas and ticks one laboratory asks for 70% ethanol, and ticks may also be sent in a tube without alcohol. If a tick needs to be removed, it is gripped, in gloves, with fine forceps as close to the skin as possible and pulled out slowly and steadily without crushing or twisting. If a particular parasite is suspected, this is noted on the submission form.

Cats and dogs

Sources

1. Iowa State University Veterinary Diagnostic Laboratory — Parasitology services (organism identification, submission)
2. CAPC (Companion Animal Parasite Council) — Ticks guidelines
3. Merck Veterinary Manual — Tapeworms in Dogs and Cats
4. VCA Animal Hospitals — What to do if you spot worms in your pet’s poop