wk 4 VEA+112+Common+Parasites

Common Internal Parasites

Overview

• Basic information for the Veterinary Assistant

Introduction to Parasitology

• Parasitology and testing procedures reviewed in Veterinary Practice.

• Focus on common parasites treated in dogs and cats.

Intestinal Parasites

Common Concerns

• Pet owners often ask how their puppy has worms.

• Intestinal parasites are frequently diagnosed through fecal samples.

Roundworms

Characteristics

• One of the most common intestinal parasites in young animals.

• Adult roundworm resembles "spaghetti" in size and shape.

• Lives in the small intestine; sometimes passed in stool or vomit.

• The Ascaris lumbricoides (giant roundworm) eggs are considered the most environmentally resistant internal parasite, capable of surviving for extended periods in soil and on various surfaces, even under harsh condition

Transmission

• Dogs and cats ingest eggs from the environment (egg hatching in the small intestine).

• Female worms lay eggs in cats; in dogs, larvae migrate through the circulatory system to the respiratory system, are coughed up, swallowed, and mature in the intestines.

• Roundworm larvae can encyst in dog tissues for months.

Lifecycle of Roundworms

1. Eggs: Present in feces, soil, or carried by rodents.

2. Infection: Puppies can be born with roundworms or acquire them through lactation.

3. Symptoms: Nutrient absorption interference, digestion issues, signs include weight loss, dull coat, and pot-bellied appearance.

Diagnosis and Treatment

• Diagnosis via fecal flotation for eggs or adult worms in feces/vomit.

• Treatment includes worming medications (first treatment kills adults; repeat in 2-4 weeks).

• Annual fecal exams and monthly preventative medications recommended; maintain cleanliness in yards and litter boxes.

Hookworms

Characteristics

• Hookworms have teeth-like structures to attach to the intestinal wall and feed on blood.

Transmission

• Can be ingested from contaminated soil, water, or through skin penetration, uterus, or lactation.

• Larvae entering the skin migrate to lungs, are coughed up and swallowed, maturing in the intestine.

Effects

• Can lead to anemia, weak animals, black tarry stools, and stunted growth in young animals.

Diagnosis and Prevention

• Similar to roundworms: fecal flotation for eggs, treatment can often overlap.

• Regular exams and hygiene measures are critical.

Whipworms

Characteristics

• Typically found in dogs; have a whip-like appearance.

• Live in the large intestine and cecum.

Transmission

• Ingested via contaminated food, water, or soil.

Effects

• Cause inflammation in the intestine, leading to diarrhea, mucus, weight loss, anemia, and hemorrhage.

Diagnosis and Treatment

• Diagnosed through fecal flotation. Worming medications repeated in 2-4 weeks.

• Resistant eggs can live in soil for years; cleanliness is essential.

Tapeworms

Characteristics

• Flat, segmented worms with suckers for attachment to intestines.

• Segments contain reproductive organs and eggs.

Transmission

• Require an intermediate host (usually fleas). Infection occurs when an animal ingests an infected flea.

Symptoms

• Possible abdominal discomfort, vomiting, and visible parasites (resembling grains of rice).

Diagnosis and Treatment

• Segments around the hind end noted; fecal flotation confirms infection.

• Treatment and flea control are crucial.

Giardia

Characteristics

• Protozoa that inhabit the digestive tract; can exist in both motile and cyst forms.

• Easily contaminates the environment and water sources.

Transmission

• Animals ingest Giardia cysts from the environment; converts to trophozoites in the intestines.

Symptoms

• Most infections are asymptomatic; diarrhea may occur.

Diagnosis and Treatment

• Fecal smear analysis for motile forms; antigen tests available (Idexx SNAP test).

• Maintain cleanliness in habited areas.

Heartworm

Characteristics

• Adult worms reside in the heart and pulmonary arteries.

• Dogs may have multiple worms; cats usually have one or a few.

Transmission

• Begins when a mosquito bites an infected host, transmitting larvae (L1 to L3).

Lifecycle

• Larvae migrate via thoracic muscles, entering veins and reaching the heart; develop in 6-9 months.

Clinical Signs

In Dogs

• Low numbers of heartworms often asymptomatic; highly infected dogs may exhibit exercise intolerance, coughing, and signs of heart failure.

In Cats

• Signs often minor; may see respiratory issues, weight loss, and vomiting.

Diagnosis and Treatment

• Initial antigen test for adult worms; further tests for active infections.

• Treatment includes stabilizing patients, followed by administration of adulticide.

• Strict exercise restriction necessary post-treatment to prevent complications.

Prevention

• Start heartworm prevention in puppies as early as 8 weeks; annual testing and monthly preventative recommended for all pets.

References

• Taylor, M., Coop, R. & Wall, R. (2007). Veterinary Parasitology, 3rd edition. Blackwell Publishing.

• Sirois, M. (2021). Veterinary Assisting Textbook, 3rd edition. Elsevier.