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CRS2 > SDL: Small Animal Cardiorespiratory Parasites > Flashcards

SDL: Small Animal Cardiorespiratory Parasites Flashcards

1
Q

Give examples of nematodes which have a lung phase but are not lungworms

A

Ascaris suum
Parascaris equorum
Toxocara cati
Toxocara canis

Ancylostoma caninum
Strongyloides stercoralis

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2
Q

Discuss the clinical signs and the diagnosis of nematodes that have a lung phase but are not lungworms

A

Usually migration does not cause clinical signs unless there is a large burden

Seen often in young puppies as worms migrate through the lungs

May be difficult to diagnose as signs occur before the patent period so faecal egg counts will be negative

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3
Q

Describe a common ascarid life cycle (e.g. Ascaris suum in pigs)

A
  1. Pig ingests eggs (L1-L2 in the egg)
  2. Eggs hatch in intestine (L2)
  3. Migration to HP vein and liver where L3 develops
  4. Migration to heart and lungs where L4 develops
  5. Coughed up and swallowed –> adult develops in intestine
  6. Eggs in faeces
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4
Q

Name some primary cardiorespiratory parasites

A 
Metastrongyloidea superfamily: 
Oslerus osleri (Filaroides osleri)	
Filaroides spp.			
Crenosoma vulpis				
Aelustrongylus abstrusus		
Angiostrongylus vasorum

Trichuroidae:
Capilaria aerophila

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5
Q

What are the clinical signs of O. osleri?

A

Pre-patent period varies between 10-18 weeks

Nodules in which worms live appear around 2 months from infection–> immune response to adults in trachea and bronchus causes the worm to encapsulate

Clinical signs may include chronic cough (often dry rasping cough, particularly after exercise, more notable in young dogs: 6-12months)

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6
Q

Diagnosis of O. osleri

A

Characteristic nodules (1-1.5cm) can be seen via bronchoscopy– particularly at the tracheal bifurcation

Sampling of tracheal mucus to identify eggs and larvae (characteristically coiled in appearance)

L1 in faeces or BAL fluid (+ eosinophils)

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7
Q

Treatment of O. osleri

A

Can be difficult to treat- nodules remain and may even calcify and cough persists

Fenbendazole- 50mg/kg daily for 10 days and often need to repeat 4 weeks later

Check in-contacts

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8
Q

Describe the clinical signs, diagnosis and treatment of Filaroides hirthi

A

Life cycle same as Oslerus osleri

Infection is generally asymptomatic (can see clinical signs in immunosuppressed dogs or dogs with other diseases)

Diagnosis usually found at post mortem
Radiographs often show diffuse broncho-interstitial patterns and rarely alveolar patterns

Treatment is rarely indicated but fenbendazole same as O. osleri where indicated

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9
Q

Describe the life cycle, clinical signs, diagnosis and treatment of Crenosoma vulpis

A

Usually a parasite of wolves and foxes but occasionally affects dogs

Indirect life cycle involving slugs and snails as intermediate hosts
High incidence in autumn due to acquisition of infections in summer

Chronic bronchopulmonary disease and productive cough

Adults live in bronchi and bronchioles where they cause bronchitis- NO nodules

Investigate and treat as Oslerus osleri

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10
Q

Describe the life cycle of Capillaria aerophila

A

Infects the trachea and occasionally nasal passages and frontal sinuses of dogs and cats

Life cycle is both direct (major) and indirect (minor)

  • female deposit eggs in lungs
  • coughed up and pass out in faeces
  • 5-6 weeks to reach infectivity (long survival in environment)
  • ingestion of embryonated eggs completes the direct life cycle
  • ingestion by earthworms and hatching to infective larval stage occurs in indirect life cycle
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11
Q

Describe the clinical signs of Capillaria aerophila

A

Light infections usually asymptomatic

Moderate to severe infections:

  • Rhinotracheitis and or bronchitis
  • Wheezing cough and sneezing
  • Dyspnoea in severe infections
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12
Q

Describe the diagnosis and treatment of Capillaria aerophila

A
  • Faecal egg count
  • Rarely peripheral eosinophilia
  • Radiographs may reveal mixed bronchial and alveolar patterns
  • BAL cytology

Treatment as for Oslerus and Crenosoma (fenbendazole)

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13
Q

Describe the life cycle of Aelurostrongylus abstrusus (feline lungworm)

A

Indirect life cycle
Cats= definitive hosts
Snails/ slugs= intermediate hosts
Rodents, birds, amphibians, reptiles= paratenic hosts

  • L1 passed into faeces
  • L3 develops within intermediate host
  • Cat usually infected by ingesting the paratenic host (after they have eaten the intermediate host)
  • (May survive in intermediate host for up to 2 years)
  • (Can remain viable as cyst form in paratenic host for up to 4 months)
  • L3 then released into the alimentary tract
  • Travel to lungs via blood or lymphatics
  • Adults reside in the alveolar duct and terminal bronchioles
    (Loose living–> no nodule)
  • Eggs laid develop into L1 within the lung, coughed up and swallowed passing out in faeces

Pre-patent period between 4-6 weeks
Duration of patency around 4 months
Some worms can survive in the lungs for several years

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14
Q

Describe the clinical signs of Aelurostrongylus abstrusus (feline lungworm)

A

Usually no clinical signs- self-limiting infestation in young cats

Signs (usually limited to chronic mild cough) related to infective dose

Recent reports of hypoventilation and respiratory acidosis in affected cats
Rarely, severe infections may develop pleural effusion

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15
Q

Describe the diagnosis of Aelurostrongylus abstrusus (feline lungworm)

A 
Faecal examination (most sensitive method)--> smear, flotation or Baermann 
May require repeated samples as intermittent shedding

Radiographs–> diffuse bronchial pattern, may see associated nodules

BAL- may see larvae in wash fluid, increased proportion and number of eosinophils

Sensitive PCR has been developed for pharyngeal swabs or faeces but not yet commercially available

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16
Q

Describe the treatment of Aelurostrongylus abstrusus (feline lungworm)

A

Fenbendazole –at 50mg/kg PO SID for 3 days – although may require longer course of 10-14 days

May require additional anti-inflammatory or bronchodilator therapy during treatment of respiratory signs worsen

17
Q

Describe the lifecycle of Angiostrongylus vasorum

A

Sometimes called a heartworm but this is a misnomer–> it is a vascular worm (aka French Heartworm) –> adults live in pulmonary arteries

Indirect life cycle:
Dogs= definitive host
Slugs/snails= intermediate host

  • eggs laid in pulmonary vessels then carried into capillaries to hatch
  • L1 penetrate into the alveoli, migrate to the trachea to be coughed up then swallowed
  • passed out into faeces
  • further development within IH
  • L3 travel to abdominal LNs where two moults take place (liver heavily compromised 10-25dpi)
  • proceeds to vascular space (aberrant migration may occur at this point)

PPP= 7 weeks

18
Q

Describe the clinical signs of Angiostrongylus vasorum

A

Often complex presenting signs, not limited to respiratory tract
Early stages of infection are often asymptomatic

Clinical signs when present typically involve three major body systems:
- Cardiorespiratory– degree of signs associated with worm burden, various respiratory signs including chronic cough,
ex intolerance, syncope, dyspnoea,
tachypnoea
- Coagulopathies - anaemia, subcutaneous haematomas, internal haemorrhages, prolonged bleeding from wounds or after surgery, thrombocytopenia, prolonged APTT and OSPT, elevated D-dimer
- Neurological dysfunction- paresis, depression, seizures, spinal pain, behavioural changes, ataxia and loss of vision

19
Q

Why are the signs of A. vasorum so diverse?

A

Adult antigens:

  • Cause Type III hypersensitivity (immune complex deposition)
  • Complement activation
  • Immune infiltrate in lungs and other tissues

Egg deposition/L1:

  • Pulmonary inflammation/granuloma formation
  • Pulmonary arteriolar vasoconstriction
  • End arteritis and fibrosis of vessels
20
Q

Describe the diagnosis of Angiostrongylus vasorum

A

Signs may be very suggestive

Detection of L1- flotation techniques, smear methods, BAL

SNAP test

Radiography, biochemistry, CBC may help support

21
Q

Describe the management of Angiostrongylus vasorum

A

Currently 2 products are licensed- advocate spot-on and milbemax/milbactor/milpro/milquantel

Fenbendazole is effective but unlicensed (some people suggest treating at weekly intervals every 3 weeks for 3 treatments)

Levamisole and ivermectin are also effective

22
Q

Describe the treatment of Angiostrongylus vasorum

A

Supportive treatment (in addition to anthelmintics):

  • bronchodilators (aid with airway hyperresponsiveness)
  • corticosteroids (reduce tendency for acute deterioration after beginning anthelmintic therapy)
  • phosphodiesterase inhibitors (for ongoing PH)
  • cage rest and possible oxygen therapy if dyspnoeic
23
Q

Describe the prevention of Angiostrongylus vasorum

A

No licensed drugs for prevention

Treatment in PPP with milbemycin oxime or moxidectin prevents establishment of adult parasites

Try to limit exposure to slugs and snails

CRS2 (64 decks)

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