Veterinary Parasitology 1: Nematodes of Dogs and Cats

Vocabulary flashcards testing key concepts, morphology, clinical signs, and life cycles of canine and feline nematodes.

Nematoda Body Cavity

Nematodes possess a pseudocoelom rather than a true coelomic cavity.

Ancylostoma Egg Morphology

Eggs are thin-shelled, multicellular, and oval-shaped.

Toxocara canis cervical alae

Prominent cuticular expansions on the anterior end that give the parasite its common name, arrowhead worm.

Ascarids

A group of round-bodied nematodes commonly referred to as roundworms.

Trichuris vulpis Infection Route

Dogs become infected by ingesting embryonated L1 eggs from the environment.

Ancylostoma braziliense in kittens

Transmammary transmission to kittens does not occur in this species.

Stichosome Esophagus

A specialized esophagus composed of a linear row of cells called stichocytes, characteristic of Trichuris vulpis.

Toxascaris leonina egg morphology

Eggs are slightly oval to round, smooth on the exterior, unicellular, and light/wavy on the inside.

Ancylostoma tubaeforme Pathogenicity

Recognized as the most pathogenic hookworm species in felines.

Trichuris vulpis Prepatent Period

Ranges from 11 to 13 weeks ( $3\,\text{months}$).

Strongyloides stercoralis diagnosis

Recovering L3 filariform and rhabditiform larvae in fecal culture or fresh feces.

Ancylostoma Female Caudal Region

Female hookworms lack a copulatory bursa, which is a membranous expansion present only in males.

Ancylostoma(hookworm) egg development

At environmental temperatures around $77\,^{\circ}\text{F}$.

Strongyloides shedding in cats

In US, cats generally shed larvae rather than eggs in their feces.

Rhabditiform Esophagus

Consists of three distinct parts: corpus, isthmus, and bulb.

Ancylostoma caninum Prepatent Period

10 days to 4 weeks (typically $2\,\text{weeks}$).

Piperazine

An anthelmintic medication specific for treating ascarid infections.

Toxocara canis Prepatent Period

Typically $3\,\text{weeks}$ to 4 weeks.

Toxocara cati Prepatent Period

Approximately $8\,\text{weeks}$.

Toxascaris leonina Prepatent Period

From 8 (9) to 10 weeks

Toxocara canis Infective Stage

An embryonated egg containing an L3 larva.

Ancylostoma caninum Infective Stage

Free-living L3 larval stage.

Strongyloides stercoralis infective stage

The L3 filariform larva.

Trichuris vulpis Infective Stage

An egg containing an L1 larva.

Uncinaria stenocephala Infective Stage

The L3 larval stage.

Turbellaria

A class of flatworms (phylum Platyhelminthes) that are free-living and nonparasitic.

Neonatal Ascarid Infection

Puppies showing ascarid eggs in feces at $3\,\text{weeks}$ of age were infected in utero with Toxocara canis.

Peracute Hookworm Infection

Severe infection causing acute blood loss, severe anemia, and sudden death in puppies during their second week of life.

Ancylostoma tubaeforme clinical signs

Infected cats display pale mucous membranes due to blood-loss anemia.

Ancylostoma caninum human zoonosis

Associated with eosinophilic enteritis and cutaneous larval migrans in humans.

Ancylostoma caninum in puppies

Transmammary transmission through colostrum and milk is the primary route for young puppies.

Baylisascaris procyonis

Raccoon ascarid whose migrating larvae cause severe neural larval migrans in animals and humans.

Fresh Trichuris eggs

Unsegmented (unicellular) eggs; prominent bipolar plug at each end.

Feline nematodes

Adult Toxocara cati worms passed in cat feces measure approximately $5\,\text{cm}$ in length.

Severe Canine Strongyloidiasis

Clinical disease characterized by a soft cough and watery diarrhea.

Strongyloides treatment

Fenbendazole administered daily for 5 consecutive days.

Trichuris vulpis induced Hematochezia

Infection causes irritation of the colon/cecum resulting in fresh bright red blood in stool accompanied by tenesmus.

Cotyloda

Pseudophyllidean tapeworms characterized by a bothriated scolex, acquired by dogs eating raw fish.

Toxascaris egg infectivity

Eggs require $1\,\text{week}$ in the environment to develop into the infective stage.

Why is Toxocara canis is hard to eradicate?

Environmental control is difficult; the egg shell is extremely thick and impervious to chemical disinfectants.

Dipylidium caninum host transmission

Dogs become infected by ingesting adult fleas containing cysticercoids.

Hookworm Primary Habitat

Adult worms reside attached to the mucosa of the small intestine.

First-Hour Fecal Larva

Larvae retrieved from fresh dog feces within $1\,\text{hour}$ of defecation are Strongyloides stercoralis.

Ancylostoma caninum in the environment

Fecal egg prevalence exceeds $60\%$ in adult outdoor dogs.

Toxocara canis adult dimensions

Large intestinal parasite possessing 3 lips, a thick stoma, and measuring up to $5\,\text{inches}$ in length.

Ollulanus tricuspis Treatment

Managed and treated using Fenbendazole.

Spirocerca lupi Tx

Fenbendazole, Ivermectin, Pyrantel, or surgical removal of esophageal nodules.

Physaloptera spp Therapeutics

Treated effectively with Pyrantel Pamoate or Fenbendazole.

Canine Whipworm Therapeutics

Treated using Fenbendazole.

Pyrantel Pamoate treatments

Effective against both hookworms and ascarids, but inactive against whipworms.

Ancylostoma caninum Dentition

Buccal cavity contains 3 pairs of ventral teeth.

Uncinaria stenocephala dentition

Possesses chitinous cutting plates instead of teeth.

Ancylostoma braziliense dentition

2 pairs of teeth.

Ancylostoma tubaeforme dentition

Buccal cavity contains 3 pairs of teeth in feline hookworms.

Cutaneous Larval Migrans

Zoonotic skin eruption in humans caused by penetrating hookworm larvae.

Transmammary Route

Among canine/feline hookworms, transmammary transmission occurs only in Ancylostoma caninum.

Toxocara cati definitive host

The cat

Baylisascaris procyonis definitive host

Raccoon.

Ollulanus tricuspis mode of infection

Host ingests L3 larvae present in vomitus.

Physaloptera Infection Mode

Acquired by ingesting infective L3 larvae in intermediate (insects) or paratenic hosts.

Spirocerca lupi Infection Mode

Ingesting L3 larvae within dung beetles (intermediate host) or paratenic hosts.

Ascarid Parasites

Toxocara canis, Toxocara cati, Toxascaris leonina, and Baylisascaris procyonis.

Female Nematode Posterior Anatomy

Characterized by an anal pore and uterus, lacking a copulatory bursa.

Male Hookworm Posterior Anatomy

Characterized by a copulatory bursa with finger-like rays and copulatory spicules.

Fecal Flotation Method

Standard diagnostic technique for identifying ascarid, hookworm, and whipworm eggs.

Trichuris vulpis egg

Football or barrel-shaped; symmetrical bipolar end plugs.

Ollulanus tricuspis clinical signs

Chronic gastritis, increased gastric mucous production, vomiting, and weight loss in cats.

Whipworm GI Location

Adult whipworms reside in the cecum and colon of the host.

Spirocerca lupi Lesion Site

Adult worms induce fibrotic nodules in the esophageal wall.

Baermann Technique Application

Selected for isolating active larval stages, such as Ollulanus tricuspis or Strongyloides.

Fecal Sedimentation Application

Diagnostic procedure of choice for recovering heavy eggs like Physaloptera spp. and Spirocerca lupi.

Physaloptera egg morphology

Oval, thick-shelled, transparent, and larvated when shed.

Visceral Larval Migrans

Zoonotic disease in humans caused by systemic migration of Toxocara larvae through organs.

Trichuris vulpis zoonotic potential

Canine whipworms generally considered non-zoonotic to humans.

Neural Larval Migrans

Severe zoonotic condition caused by Baylisascaris procyonis larvae invading brain and CNS tissue.

Stomach Worm Zoonotic Potential

Gastric nematodes of pets (Ollulanus, Physaloptera, Spirocerca) are not zoonotic.

Trichuris vulpis clinical signs

Weight loss, unthrifty coat, anemia, watery diarrhea, and hematochezia.

Parasite

An organism living in or on a host species that derives nutrients at the host's expense.

Phylum Platyhelminthes

Flatworms lacking a body cavity, divided into Trematodes (flukes) and Cestodes (tapeworms).

Indirect Life Cycle

A parasite life cycle requiring one or more intermediate hosts for larval development.

Direct Life Cycle

A parasite life cycle completed within a single host species without an intermediate host.

Spirocerca lupi egg morphology

Distinctive small, thick-shelled, larvated egg with a paperclip-like appearance.

Phylum Nematoda

Unsegmented roundworms possessing a cylindrical shape and a pseudocoelomic body cavity.

Toxascaris leonina egg morphology

Slightly oval to round egg with a smooth outer shell and a wavy inner membrane around an unsegmented zygote.

Spirocerca lupi Nodules

Granulomatous esophageal masses caused by adult worms that may require surgical excision.

Spirocerca lupi clinical signs

Leads to dysphagia, regurgitation, vomiting, gastritis, and esophageal ulceration.

Physaloptera spp. clinical manifestations

Gastric mucosal irritation resulting in chronic vomiting, gastritis, and stomach ulcers.

Common Zoonotic Nematodes

Includes ascarids (Visceral/Ocular Larval Migrans) and hookworms (Cutaneous Larval Migrans).

Ancylostoma clinical signs

Blood feeding causes pale mucous membranes, melena, diarrhea, weight loss, and lethargy.

Ollulanus tricuspis is found where in the host?

Embedded within the gastric mucosa of the stomach.

Hookworm Egg Identification

Oval shape with a thin, smooth outer shell containing an early morula (multicellular stage).

Pyrantel Pamoate Limitations

Ineffective against Trichuris vulpis (whipworms).

Copulatory Bursa

Specialized caudal structure in male bursate nematodes used to clasp the female during mating.

Toxocara spp. egg Identification

Spherical egg featuring a dark unsegmented center and a pitted, rough outer protein coat.

Hookworm Target Location

Adults inhabit the small intestine of the host.

Physaloptera is found where?

Adults inhabit the stomach of dogs and cats.

Spirocerca lupi Target Organ

Esophagus.

Prepatent Period

The time interval between host infection and the initial detection of parasite reproductive stages (eggs/larvae).

Ollulanus Female Tail Structure

Female worm possesses a distinct tricuspid (three-pointed) tail tip.

Arrowhead Worm

Common nickname for Toxocara canis derived from its arrow-shaped cervical alae.