Respiratory parasites

Question 1

Describe lifecycle of Linguatula serrata (dog tongue worm)

Answer 1

Symptoms:
Nasal discharge, nose bleeds (epistaxis) & sneezing

Treated with Milbemycin oxime

1. Adult worm in nasal cavity lays eggs which are shed with host’s nasal secretions
2. Intermediate host (ruminant) ingests eggs
3. Larvae migrate from intestinal wall to various organs
4. Larvae develop into nymphs
5. Intermediate host ingested by definitive host (predation or scavenging)
6. Nymphs migrate to nasal cavity & develop into adult worms

Question 2

Describe lifecycle of Pneumonyssus caninum (dog nasal mite)

Answer 2

Treated with moxtidectin or milbemycin oxime

1. Female mite lays eggs in host nasal cavity
2. Larvae hatch & feed on host’s nasal tissue & secretions
3. Nymphs moult into adult mites

Question 3

Describe lifecycle & importance of Oestrus ovis

Answer 3

Prevalence within sheep flock may be as high as 80%
Ivermectin may reduce prevalence

Clinical signs:
Nasal discharge, laboured breathing, loss of appetite

ELISA test used for diagnosis

Treated with moxidectin or ivermectin

1. Female fly lays eggs on hairs around nostrils
2. After hatching larvae migrate into nasal cavities & sinuses of host where they mature
3. Larvae leave nasal cavity & pupate in soil
4. Adult fly emerges from pupa

Question 4

Describe lifecycle & importance of Syngamus trachea (gapeworm)

Answer 4

Economically important in turkeys & chickens

Clinical signs are gaping & weight loss

Diagnosis: eggs in faeces & adults in trachea

Treated with fenbendazole or flubendazole

1. Adult worms live in trachea & bronchi of host
2. Worms lay eggs which are shed through host’s respiratory secretions
3. Eggs ingested by host or intermediate host which is then ingested by host
4. Larvae develop into infective larvae in body cavity
5. Larvae migrate to respiratory tract

Question 5

How can nasal & tracheal parasites be diagnosed

Answer 5

Microscopic examination
ELISA test
Radiographs
PCR testing
Endoscopy

Question 6

What are haematological abnormalities associated with parasitic disease

Answer 6

Low PCV
High WBC
High neutrophils
High eosinophils
Low platelets

Question 7

Common anthelmintics in young horses

Answer 7

Benzimidazoles (e.g. fenbendazole)
Interrupts parasite energy metabolism

Macrocytic lactones (e.g. moxidectin, ivermectin)
Block neuronal signals of parasites which are then paralysed/expelled out of body

Pyrantal
Paralysis of parasite

Praziquantal
Causes severe spasms & paralysis of parasite muscles