ANSC 221_PPT10_Parasites (1)

Overview of Internal Parasites

• Parasites, external and internal, are prevalent in horses

• Complete elimination of insects, worms, and arachnids is not possible

• Effective parasite control is essential for good equine health

Life Cycle of Parasites

• Life cycle stages of internal parasites can impact equine health

  • Mature female worms lay eggs in feces

  • L1 larvae hatch, transition to L2, and finally L3 which is infectious

Impact of Internal Parasites

• Internal parasites pose significant health risks

  • Can cause anemia, diarrhea, weight loss, poor condition, and overall debility

  • Young horses may suffer permanent bowel damage leading to malabsorption

  • Internal parasites can contribute to cases of intestinal colic

Types of Internal Parasites

Strongyles

• Considered one of the most damaging equine parasites

  • Two primary groups: Large Strongyles and Small Strongyles

  • Large Strongyles (bloodworms) migrate through circulation causing damage to blood vessels

  • Small Strongyles stay within gut walls

Life Cycle of Strongyles

• Life cycle begins with eggs in feces, becoming free-living larvae

• Horses ingest larvae while grazing, leading to different paths for large and small strongyles

Patient Comparison

• Common equine strongyles include:

  • Cyathostominae, Strongylus edentatus, Strongylus equinus, Strongylus vulgaris

Specific Strongyles

Large Strongyles

• Include Strongylus vulgaris, Strongylus edentatus, Strongylus equinus

  • Strongylus vulgari can cause severe arterial damage leading to life-threatening conditions such as thrombosis and embolism

Effects of Strongyles

• Thromboembolism can result in colic and severe abdominal pain

• After five months in the arteries, larvae return to intestines where they mature into adults

Small Strongyles

• Over 40 species in the cecum and colon

  • Causes include colic, bleeding, anemia, protein loss, and malabsorption

  • In spring, larvae emerge rapidly leading to severe diarrhea

Managing Strongyles

• Essential focus for deworming programs

• Protective measures against reinfection include:

  • Rotate dewormers to mitigate resistance

  • Regular testing and treatment

Roundworms (Ascarids)

• Specifically Parascaris equorum that mainly affect young foals

  • Adult roundworms can reach up to 12 inches in length

  • Diagnosis via fecal tests and lack of growth in foals

Signs of Ascarids

• Symptoms may include malnutrition, retarded growth, rough coat, potbelly, persistent cough, and nasal discharge

Treatment and Prevention of Ascarids

• Use dewormers like Oxibendazole and Piperazine

  • Interval deworming starting at eight weeks of age

Threadworms

• Strongyloides westeri is a significant parasite, particularly affecting foals through the dam's milk

• Treatment includes careful monitoring and deworming of mare and foal

Stomach Bots

• Caused by the larvae of bot flies; three species exist based on egg deposits

• Bots can lead to severe complications like colic and ulcers

Treatment & Prevention of Bot Infestations

• Regular cleaning and treatment with anthelmintics can minimize bot populations

Pinworms

• Common in stabled horses; they cause itching and irritation

• Treatment requires cleanliness and use of anthelminthic medication

Tapeworms

• Once deemed insignificant, tapeworm infections are now known to impact colic cases

Lungworms

• Associated with burros and donkeys, showing symptoms like cough and labored breathing

Stomach Worms (Habronema)

• Can cause gastritis; control through fly management and deworming

Hairworms (Small Stomach Worms)

• Difficult to diagnose due to egg similarity to other worms; frequent deworming is necessary

General Control of Internal Parasites

• Regular deworming schedules and fecal testing are critical

• Environment management to reduce reinfection risk

Deworming Agents

• Various classes: Benzimidazoles, Organophosphates, Piperazines, Carbamates, Avermectins

Important Deworming Guidelines

• Treat all horses simultaneously to prevent contamination

• Develop and adhere to a structured deworming schedule

Deworming Schedules

Adult Horses

• Schedule for effectiveness at preventing reinfestation

Foal Specific Schedule

• Interval deworming adapted for developmental needs

Strategic Deworming Program

• Regular fecal examinations help track parasite burdens and drug efficacy

Environmental Control Practices

• Crucial for effective parasite management; regular manure removal and proper feeding practices essential