Academic onefile – document – acute neurological signs as the predominant clinical manifestation in four dogs with angiostrongylus vasorum infections in denmark anoxic tank

Angiostrongylus vasorum

, also known as the french heartworm, is an approximately 13-21 millimetre

Gastropod-borne nematode, recognised in endemic areas of europe [1, 2, 3, 4,

5, 6, 7, 8], north and south america [9, 10, 11, 12] and uganda [13, 14]. In

Endemic areas, the parasite is a well-known cause of respiratory disease

(canine pulmonary angiostrongylosis, CPA) especially in young dogs which,

Along with other canine species, e.G. The fox, act as the definitive hosts in

The life cycle of the parasite [1, 3, 15]. The adult worms primarily inhabit

The pulmonary arteries and right cardiac ventricle of the canine host,

Resulting in a verminous pneumonia with obliterative thrombotic endarteritis

And fibrosis [16].Anoxic tank the primary clinical signs are reported to be cough,

Exercise intolerance, dyspnoea and right sided heart failure, all of which

Are directly related to the respiratory system. However, non-specific

Clinical signs such as vomiting, diarrhoea or anorexia are also frequently

Reported [3]. Furthermore, disorders of haemostasis resulting in severe

Haemorrhages have been identified as possible complications of the CPA

Complex [3, 15]. The exact pathophysiological mechanisms remain unclear [3,

15], but a chronic low grade disseminated intravascular coagulation (DIC)

With associated consumption of both platelets and coagulation factors is most

Commonly suggested [17, 18]. Immunemediated thrombocytopenia associated with

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A. Vasorum

Infections has also been reported as a possible cause of bleedings [19].

Prolongation of clotting times and decrease of coagulation factors, e.G. Von

Willebrand factor and factor V have been reported in both experimentally and

Naturally infected animals, although not consistently [17, 20, 21].

At necropsy, a subcutaneous haematoma of 10 x 20 centimetres was detected on

The left side of the thorax. In the left cerebral hemisphere, a haematoma,

2.5 centimetres in diameter, was extending into the left lateral ventricle

(figure 1). Histopathology (HE) of the area peripheral to the cerebral

Haematoma revealed the presence of gitter cells and changes compatible with

Granulation tissue including proliferated fusiforme cells, and

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Capillaries/venules and collagen as shown by masson trichrome staining

(figure 2). In addition, several acute microscopic haemorrhages were observed

In the brain. Acute malacic foci were also encountered as well as foci of

Gitter and glial cells. Gitter cells (macrophages) occasionally contained

Haemosiderin as identified by the perl’s prussian blue stain (figure 3).

Moderate cuffing and meningeal infiltrates of macrophages, lymphocytes/plasma

Cells and neutrophils were identified in addition to dense focal infiltrates

Of neutrophils (absence of eosinophilic granules by luna staining).

A seven-months-old danish/swedish farmdog was referred with progressive

Ataxia and mucosal membrane petechiae of 24 h duration.Anoxic tank A diagnosis of

A. Vasorum

Had already been established by a faeces smear performed by the local

Veterinarian 24 h prior to referral. On presentation, the dog was alert but

Non-ambulatory paraplegic and in pain. Petechial haemorrhages were present in

Both scleras, and oral and ocular mucosal membranes. The neurological

Examination revealed no cranial nerve deficits. Both thoracic limbs were

Hypertonic and there was a bilateral flaccid paralysis of the pelvic limbs.

Proprioceptive placing reactions were normal in the thoracic limbs but absent

In the pelvic limbs. Patellar and withdrawal reflexes were bilaterally absent

In the pelvic limbs, but the perineal reflex was preserved. Cutaneous trunci

Reflex was normal.Anoxic tank neurological signs seemed compatible with

Schiff-sherrington syndrome, and a T3-L3 lesion was suspected. However, as

The cutaneous trunci lesion was normal in the T3-L3 region, multifocal

Disease was considered with a possible lesion cranial to C6, giving rise to

Upper motor neuron signs of the thoracic limbs, and a second lesion in the

Lumbosacral plexus (L4-S2) causing lower motor neuron signs of the pelvic


On neurological examination immediately upon admission, the dog was alert,

But unable to bear weight on its pelvic limbs. There were no cranial nerve

Deficits and thoracic limb reflexes and reactions were normal. Proprioceptive

Placing reactions were bilaterally absent in the pelvic limbs.Anoxic tank patellar

Reflexes were absent and withdrawal reflexes were reduced, whereas the

Perineal reflex was normal. The cutaneous trunci reflex was slightly

Decreased in the lumbar region. Deep pain perception and some voluntary

Movement were initially preserved, but the dog’s neurological status

Gradually worsened during hospitalisation with complete loss of withdrawal

Reflexes and voluntary movement of the pelvic limbs. Based on the

Neurological findings, a spinal cord lesion located at segments L4-S2 was

Suspected. Thoracic radiographs revealed a diffuse lung pattern of

Interstitial and peribronchial hyperdensity. Blood analysis revealed a

Slightly decreased PCV (0.35), mild thrombocytopenia (145 x 10 9

/L), hyperglobulinaemia (72) and slightly increased D-dimers (0.6 mg/L)

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(additional file 2: table S2). A magnetic resonance imaging scan (esaote

Vetscan 0.2 tesla) with T1- and T2-weighted images (WI) of the lumbosacral

Region was performed in transverse and sagital planes. Contrast was not

Administered. On T1 weighted images (T1-WI), a hypointense area was

Recognised subdurally at the level of vertebrae L4-L6, lateralised to the

Right and compressing the spinal cord towards the left (figure 6). The same

Finding appeared iso- to hyperintense on T2 weighted images (T2-WI). Caudal

To this was an area of hyperintense swelling on T2 (figure 7). These findings

Were considered compatible with an acute haematoma with peripheral oedema in

The area. A baermann test was accordingly performed revealing multiple

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A. Vasorum larvae


CPA is a commonly diagnosed disease in endemic areas of denmark and the UK,

Primarily presenting as respiratory disease [3, 15]. The included cases of

The present study all presented with neurological signs as the primary

Complaint, in each patient caused by one or more CNS haemorrhages resulting

From haemostatic dysfunction associated with A. Vasorum

And/or evidence of aberrant larvae. This emphasises CPA as an important

Differential diagnosis in dogs presenting with neurological signs of unknown

Aetiology. Acute non-traumatic brain haemorrhages are only infrequently

Reported in dogs [30], and A. Vasorum

Should therefore be highly suspected as the underlying cause of brain

Haemorrhages in endemic areas.Anoxic tank as opposed to ischaemic stroke, which appear

With greater frequency and which might present with similar neurological

Signs, CPA is most commonly seen in young dogs [3, 15], whereas the mean age

Of dogs reported with ischaemic stroke is 8.4-8.9 years [31, 32]. The mean

Age of dogs in the present study was 10 months (median; 17 months) which is

In accordance with previous studies of dogs naturally infected with

A. Vasorum

[3, 15]. The present study furthermore confirms haemorrhages due to

A. Vasorum

To be an important differential diagnosis to acute disc disease and

Fibrocartilaginous embolisation in dogs with acute spinal cord disease in

Endemic areas as previously reported [23, 33].

As opposed to dogs mildly to moderately infected (i.E.Anoxic tank with no signs of

Coagulopathy or neurological disease), in which survival is close to 100% [3,

15], the prognosis of CPA should be considered guarded when complicated by

Haemostatic dysfunction and even more so when the condition gives rise to

Severe neurological deficits. This can also be appreciated from a review of

Neurological cases in which 11 out of 17 (65%) died despite recognition and

Treatment of A. Vasorum

In the majority [2, 20, 22, 23, 25, 26, 28, 33, 34]. Compromised blood supply

To the area involved, along with direct physical compression caused by a

Haematoma makes the CNS, which is strongly dependent on continuous supplies

Of oxygen and glucose, highly susceptible to irreversible damage.Anoxic tank

Furthermore, any attempt of surgical decompression or evacuation of the

Haematoma is severely complicated by the presence of ongoing haemostatic

Dysfunction unless addressed appropriately by blood component therapy such as

Fresh frozen plasma or cryoprecipitate [35].