Lungworms of dogs and cats Flashcards
What are some characteristics of metastrongyles?
- Lungs or related blood vessels
- Normally L1 in faeces
- L1 have typically ‘kinky’ tails – helps differentiate the species
- Normally indirect life cycles with mollusc intermediate hosts (snails and slugs)
- Lympho-tracheal migration
Name two metastrongyle species of dogs
Angiostrongylus vasorum
Oslerus osleri
Name a metastrongyle species of cats
Aelurostrongylus abstrusus
Angiostrongylus vasorum is also know as?
The French heartworm
Where do adult Angiostrongylus vasorum worms live?
In the pulmonary artery and right ventricle
Describe 2 morphological features of Angiostrongylus vasorum
2cm long
Barber pole - ovaries and gut
What are the 3 hosts of Angiostrongylus vasorum?
- Intermediate host – slugs and snails
- Paratenic hosts –frogs
- Dog/fox - main host
What is a paratenic host?
Hosts where there is no development, just allows the passing from one host to another
Define ovoviviparous
Pass eggs with the larvae already developed within them and are ready to hatch
Describe the life cycle of Angiostrongylus vasorum
- Adults go from the heart and pulmonary artery in capillaries to the lungs, eggs almost immediately hatch into L1 larvae which then move across the alveoli, up the pharynx where they are coughed up and swallowed
- No further development and L1 are passed out in the faeces, when they moult to L3 (temp dependant)
- Once in the dog the L3 larvae cross the intestinal wall, mature to L4 and into L5 adults in the abdominal LN
- Within the blood and lymphatic system they migrate via the liver and blood vessels to the heart
How are snails/slugs involved in the life cycle of Angiostrongylus vasorum?
L1 in faeces
Ingestion by slug/snail
L1 -> L3 development is temperature dependant
Slugs are ingested by dog
What is the PPP for Angiostrongylus vasorum?
5-8 weeks
What are the respiratory clinical signs of Angiostrongylus vasorum?
- Coughing
- Dyspnoea
- Weight loss
- Pulmonary hypertension
What are the non-respiratory clinical signs of Angiostrongylus vasorum?
- Often asymptomatic but can cause sudden death
- Coagulopathies: fluctuating haematoma/bleeding disorders. Worms secrete a range of anticoagulants
- Neurological
How can Angiostrongylus vasorum be diagnosed?
- Antigen SNAP test
- Radiography: Enlarged heart and pulmonary artery. Patchy alveolar and interstitial pattern.
How can Angiostrongylus vasorum be differentiated from other lungworms diagnostically?
- L1 in faeces, trans-tracheal wash or bronchoalveolar lavage
- ‘Dorsal notch’ on the tail of the L1
- 300 to 400 µm
- Baermann apparatus to detect L1
What are 2 considerations when using a Baermann apparatus?
Low sensitivity
Repeat samples every 3 days
How is Angiostrongylus vasorum treated?
- Moxidectin
- Milbemycin oxime
- Fenbendazole
How is Angiostrongylus vasorum controlled?
- Corticosteroids
- Cage rest during treatment (2-3 days)
- Prophylaxis: monthly treatment with macrocyclic lactones
- When possible, dogs should be prevented from ingesting snails or slugs.
What is the role of foxes in the epidemiology of Angiostrongylus vasorum?
They act as reservoir hosts
What is the main feature of Oslerus osleri life cycle?
Direct
Where are adult Oslerus osleri worms found?
In nodules in the trachea
How long is the PPP of Oslerus osleri?
10-18 weeks
What is the infective stage of Oslerus osleri?
L1 in sputum (thick type of mucus made in your lungs)
Describe the life cycle of Oslerus osleri
- Larvated eggs/L1 are passed by the female (ovoviviparous)
- L1 are released into the tracheal lumen, move up to the pharynx, swallowed and passed in faeces.
- Infection of the definitive host by ingestion of L1 larvae (transmission mainly by the bitch grooming/licking its pup)
- Upon ingestion/introduction into the mouth of the pup, L1 cross the intestinal wall, travel via the lymphatics and blood system to the lungs and trachea.
What are the two signs of Oslerus osleri disease?
Tracheo-bronchitis
Coughing
How is Oslerus osleri diagnosed?
- Young dogs, 1-2 years old (PPP = 10-18 weeks)
- Bronchoscopy to identify nodules
- Larvae in faeces (low sensitivity)
- Transtracheal wash or bronchoalveolar lavage cytology or tracheal swabs may reveal larvae or eggs
Which drug is used to treat Oslerus osleri?
Fenbendazole
How would you differentiate between L1 of Oslerus osleri and Angiostrongylus vasorum in the faeces of a dog?
Oslerus larvae have an S-shaped tail and Angiostrongylus larvae have a dorsal notch on their tail
Where are the adults of Aelurostrongylus abstrusus found?
Lung parenchyma
What are the features of Aelurostrongylus abstrusus?
- Affects cats
- Adults = 10mm
- L1 in faeces (‘S’ shaped tail) - 350 to 400 µm
Who are the 3 hosts of Aelurostrongylus abstrusus?
- Snail intermediate host
- Paratenic hosts = small mammal, frog, lizard
- Definitive host = cat
What is the PPP for Aelurostrongylus abstrusus
5-6 weeks
Describe the disease features of Aelurostrongylus abstrusus
- Normally asymptomatic
- Common (~7% cats infected)
- Coughing/respiratory disease
- Hyperplasia of the bronchioles, alveolar ducts and pulmonary arteries
How is Aelurostrongylus abstrusus diagnosed?
- L1 in faeces – Baermann technique: fresh faecal samples within a 3-7 day period
- L1 in transtracheal wash or bronchoalveolar lavage
How is Aelurostrongylus abstrusus treated?
- Fenbendazole: for at least 3 days, up to 7 days.
- Moxidectin, Emodepside
Name the lungworm of dogs that has anterior cuticular rings on its tail
Crenasoma vulpis
Give 3 other morphological features of Crenasoma vulpis
- 1.5cm size
- White slender
- L1 has a straight pointed tail, no notch
What are the pre-patent periods for the lungworms of dogs?
Angiostrongylus vasorum: 5-8 weeks
Oslerus osleri: 10-18 weeks
