Equine and companion animal lungworms

Question 1

Name the lungworm that affects horses

Answer 1

Dictyocaulus arnfieldi

Question 2

Where are D.arnfieldi found? 4

Answer 2

• Adult worms in smaller bronchi –> frequent cause of chronic cough.
• Raised areas of over-inflated pulmonary tissue (surrounding small bronchus, containing worms and purulent exudate).
• Hyperplastic bronchial epithelium
• Peribronchial cuffing

Question 3

Diagnosis - equine lungworm - 5

Answer 3

• CS
• Grazing Hx (donkeys!!)
• Faecal exam (only detects patent infections = small proportion of lungworm infections in horses).
• Tracheobronchial washings (large eosinophils)
• Response to anthelmintic treatment

Question 4

How can you perform a faecal exam in the horse? 2

Answer 4

• Process immediately - McMaster method - embryonated egg

- Process later - Baerman technique - L1 larva and tail spine

Question 5

Control - equine lungworm - 2

Answer 5

• don’t keep horses on pastures grazed by donkeys

- treat donkeys with appropriate anthelmintic in spring if grazed with horses (e.g. ivermectin)

Question 6

What are the 2 more common species that cause canine lungworm?

Answer 6

• Angiostrongylus vasorum

- Filaroides (Oslerus) osleri

Question 7

What is another name for Angiostrongulus vasorum?

Answer 7

French heartworm (adults reside in the right heart)

Question 8

Outline the LC of A. vasourm

Answer 8

• lungworm of dogs/foxes
• typical metastrongyloid nematode:
  
  • Indirect LC (mollusc IH)
  • Adult worms (2cm, pulmonary arteries, RHS heart)

Question 9

What are the 3 clinical forms/syndromes of A.vasorum?

Answer 9

• Cardio-respiratory signs
• Coagulopathies
• Neurological signs

Question 10

Outline the cardio-respiratory signs of A.vasorum. Mechanism?

Answer 10

• chronic cough
• exercise intolerance (young)
  HOW: BV blockage in PA (adult worms, eggs, larvae)

Question 11

Outline coagulopathy signs of A. vasorum. Mechanism?

Answer 11

• SC haematomas
• internal haemorrhage
• prolonged bleeding from wounds
  HOW: thrombocytopaenia, decreased CFs (5 and 8)

Question 12

Outline the neuroligical signs of A.vasorum. Mechanism?

Answer 12

• depends on location of haemorrhage - paresis, behavioural changes, ataxia, loss of vision, seizures)
  HOW: CNS haemorrhages

Question 13

How can A.vasorum be diagnosed? 6

Answer 13

• CS
• Imaging
• Faecal exam (L1)
• Sputum exam (L1)
• Blood
• PME

Question 14

What do you look for on radiographs if you suspect A. vasorum?

Answer 14

Peripheral lung lobe lesions - marked bronchial and peribronchial infiltrate

Question 15

Outline faecal exam (Baerman) and sputum for L1 of A. vasorum

Answer 15

• larval recovery unreliable due to low numbers
• relatively long PPP (6-10 weeks)
• intermittent egg production by adults so collect samples on 3 consecutive days.

Question 16

What might you seen on bloods with A.vasorum infection? 4

Answer 16

• Hypochromic anaemia
• Eosinophilia
• Coagulopathy tests (thromboplastin times)
• ELISA serology tests

Question 17

What might you seen on PME with A.vasorum infection? 5

Answer 17

• adult worms
• lungs - mottled, reddish-purple
• SC haematoma
• Larger BVs (–> endarteritis –> fibrosis)
• RV (endocarditis - tricuspid valve)

Question 18

How can A. vasorum be treated? 3

Answer 18

2 UK licensed anthelmintics for this:

• MOXIDECTIN (Advocate) - single dose, prevents infection for 1 months
• MILBEMYCIN (Milbemax) - weekly for 4 weeks

OFF-LABEL TREATMENT:
- Fenbendazole (Panacur) - daily for 1-3 weeks

OTHER:

• monitor course of treatment, repeat if necessary
• treat early in LC to minimise pathology
• supportive tx (fluids, O2, broncho-dilators, O2, ABs)

Question 19

How can A.vasorum be controlled? 3

Answer 19

• Regular anthelmintics (risk based)
• IH control is impractical
• Public education

Question 20

Outline the general LC for Filaroides (Oslerus) osleri

Answer 20

• dog lungworm
• ATYPICAL metastrongyloid nematode since it has a direct LC, adult worms live in tracheal nodules, transmission to puppies from bitch grooming (sputum)
• Clinical significance: asymptomatic –> chronic dry debilitating cough, associated with breeding kennels

Question 21

How can Filaroides (Oslerus) osleri be diagnosed? 2

Answer 21

• Difficult
• Baerman to recover L1 from faeces (distinct dorsal indentation) but larvae sluggish, low numbers so few recovered
• Endoscopy - view tracheal nodules and confirm diagnosis.

Question 22

How can F.osleri be treated?

Answer 22

Fenbendazole (Panacur) - licensed, 50mg/kg for 7 days

Question 23

What does Aelurostrongylus abstrusus affect?

Answer 23

Lungworm of cats, generally uncommon

Question 24

Outline the Aelurostrongylus abstrusus LC

Answer 24

• lungworm of cats, uncommon
• typical Metastrongyloid nematode - indirect LC (molluscan IH), adults worms live in lung parenchyma and small bronchioles)
• clinical significance - asymptomatic - serious respiratory problems

Question 25

Outline pathogenesis of Aelurostrongylus abstrusus

Answer 25

often asymptomatic - severe respiratory problems (immuno-compromised cat, poor prognosis)

Question 26

How can A.abstrusus be diagnosed? 3

Answer 26

• Faecal exam (Baerman - L1)
• PME - greenish nodules in lung
• Histopathology - differentiate from TB

Question 27

How can A.abstrusus be treated?

Answer 27

Fenbendazole (Panacur) - licensed - 50mg/kg/day for 3 days)

Question 28

What are other respiratory parasites of HORSES? 1, 1

Answer 28

• Parascarius equorum (migrating larvae)

- Echinococcus granulosus (hydatid cyst)

Question 29

What are other respiratory parasites of DOGS? 2, 4

Answer 29

• Toxocara canis (migrating larvae)
• Toxascaris leonina (migrating larvae)
• Crenosoma vulpis (fox lungworm)
• Filaroides spp (parenchyma)
• Linguatula serrata (tongue worm)
• Pneomonyssus caninum (nasal mite)

Question 30

What are other respiratory parasites of CATS? 2, 1

Answer 30

• Toxocara cati (migrating larvae)
• Toxascaris leonina (migrating larvae)
• Linguatula serrata (tongue worm)