Cerebellar Infarcts in the Cavalier King Charles Spaniel
Cavalier King Charles spaniels appear predisposed to develop cerebellar infarcts, or strokes. Dr. Curtis Dewey has attributed them to the “frequent presence of caudal occipital malformation syndrome (COMS) in these dogs.”
What It Is
A cerebellar infarct is a localized area of typically wedge-shaped dead tissue, called a lesion, within the cerebellum of the brain, which results from the sudden rupture of one of the cerebellar arteries, causing interference with normal blood flow through the area. Such cessation of blood flow may also be referred to as a cerebellar stroke. The effect of a stroke, and the creation of the infarct, are caused by the lack of normal oxygen delivery from the blood flow.
Symptoms
The onset of symptoms of a cerebellar infarct usually is quite sudden and dramatic. The cavalier may be behaving normally one minute, and then in an instant, become unsteady, un-coordinated, nauseous, walk uncontrollably in small circles, or even faint and fall over. The dog may tilt its head, have facial paralysis, lose its vision or control of its bowels, or change its temperament.
Some symptoms may progress over the first twelve hours, presumably due to brain swelling, while others may disappear quickly. Most symptoms should begin to lessen within a day or two.
Diagnosis
Cerebellar infarcts should be suspected in any case in which the onset of symptoms is sudden and otherwise unexplained. The dog should be taken to a veterinary clinic immediately; examination by a neurologist would be preferable. The veterinarian should conduct a complete neurological examination, in addition to blood pressure measurement, normal blood work and urinalysis, x-rays, and possibly an ultrasound and endocrine and thyroid profiles.
The symptoms may be confused with those of paradoxical vestibular syndrome, particularly the head tilt, which is the most consistent sign of unilateral vestibular dysfunction, and ataxia – loss of muscle coordination – and nystagmus, which is an involuntary rhythmic oscillation of the eyeball.
The only accurate way to diagnose an infarction is using magnetic resonance imagine (MRI), and to a limited extent, computed tomography (CT), to obtain scans of brain images. Early enough CT imaging should enable the veterinarian to determine whether the infarct was caused by a burst blood vessel (hemorrhagic), but MRI is the best device for identifying a shut down blood vessel (ischemic), which will better determine the treatment protocol.
As noted at the outset of this article, Dr. Curtis Dewey has written that:
“There appears to be a predisposition for spaniel breeds, especially cavalier King Charles spaniels, to develop cerebellar strokes. This is suspected to be due to frequent presence of caudal occipital malformation syndrome (COMS) in these dogs, with associated interference with normal basilar artery flow.”
Treatment
If the veterinarian is able to determine the underlying cause of the infarction, it should be treated promptly. Initially, mannitol may be administered intravenously to overcome any brain swelling. Mannitol is the alcohol form of the sugar, mannose, and it is an osmotic diuretic and a mild renal vasodilator. It is used to treat excessive intra-cranial pressure and to expand blood vessel openings in the brain.
If systemic hypertension is found, enalapril maleate (Enacard, Vasotec), or another ACE-inhibitor may be prescribed. ACE-inhibitors block the angiotensin converting enzyme, which is necessary to produce a substance that causes blood vessels to tighten. So, ACE-inhibitors serve to relax the blood vessels, thereby lowering the blood pressure and increasing the supply of blood and oxygen to the brain.
Amlodipine (Norvasc) may also be administered. Amlodipine is a calcium channel blocker which relaxes blood vessels so that the blood can flow more easily.
Nicergoline (Fitergol, Sermion) is an alpha-blocking cerebral vasodilator which is a vasodilator that improves blood flow to the brain and stimulates the use of oxygen and glucose. It also blocks serotonin and dopamine receptors. It is used to treat migraine headaches that are of vascular origin and other problems of a vascular nature, such as dizziness and auditory problems.
The prognosis is guarded if the symptoms are very severe and prolonged. However, dogs with less severe signs have shown rapid and dramatic recoveries.
Related Links
Veterinary Resources
MRI appearance of cerebrovascular disease in seven spaniels. Mcconnell, J. F., Garosi, L., Dennis, R., Platt, S. R. & Abramson C. J. 2003 BSAVA Congress; pg 568.
Cerebellar Infarcts in Two Dogs Diagnosed With Magnetic Resonance Imaging. Jason M. Berg and Richard J. Joseph. J Am Anim Hosp Assoc.2003;39:203-207. Quote: "Two dogs presented with severe, peracute-onset, neurological signs. Neuroanatomical localization was cerebellovestibular. Magnetic resonance imaging (MRI) was performed and revealed focal, wedge-shaped lesions in the cerebellum. Diagnosis of cerebellar infarctions was made based on peracute-onset, clinical signs, MRI, and outcome as well as ancillary diagnostic information. Both dogs recovered completely. Cerebellar infarction should be included in the differential of any dog with peracute-onset, central cerebellovestibular signs regardless of severity of clinical signs. Outcome was excellent in these dogs."
Vascular Encephalopathies. C.W. Dewey. 50° Congresso Nazionale Multisala SCIVAC, 2005. Quote: “There appears to be a predisposition for spaniel breeds, especially cavalier King Charles spaniels, to develop cerebellar strokes. This is suspected to be due to frequent presence of caudal occipital malformation syndrome (COMS) in these dogs, with associated interference with normal basilar artery flow.”
Neurological diseases of the Cavalier King Charles spaniel.
Rusbridge, C. J Small Animal Practice, June 2005, 46(6): 265-272. "CKCSs
seem to have an increased tendency towards cerebrovascular disease (McConnell
and others 2003), particularly infarction of the rostral cerebellar artery.
Affected dogs present with signs of acuteonset, rapidly progressive central
vestibular syndrome. Rostral cerebellar artery infarction in humans is
associated with cardiogenic embolism and major artery occlusive disease such as
carotid artery dissection (Yin and others 1994). The CKCS is
predisposed to mitral valve disease Haggstrom and others 1992), increased
platelet aggregation (Olsen and others 2001) and arterial disease (Buchanan and
others 1997), all of which offer some explanation for a tendency towards
cerebrovascular disease. In the UK, any CKCS presented with
signs of intracranial haemorrhage or infarction should be screened for
Angiostrongylus vasorum. This parasite can result in bleeding and coagulation
disorders, and the CKCS appears to be predisposed to infection
(Chapman and others 2004)."
Suspected cerebellar infarcts in 4 dogs. John C. Irwin, Curtis W.
Dewey. J Vet Emer & Crit Care; Sept 2007; 17(3):268-274. Quote: “Objective:
Reports of cerebellar infarction in veterinary literature are rare.
Documentation and descriptions of cerebellar infarction in human literature have
been well described. Brain lesions suspected to be infarcts have been recognized
with magnetic resonance imaging (MRI). ... Four dogs presented ... with the
history of acute onset cerebellovestibular dysfunction. All animals were imaged
using a 0.5 T super-conducting Magna GE MRI unit. Suspected cerebellar
infarction was diagnosed in all dogs based on history, physical examination, and
MRI findings. Further diagnostics were performed based on the individual case
and owner compliance. Functional recovery was favorable in 3 dogs. One dog was
euthanized shortly following the onset of neurological dysfunction. ...
Cerebellar infarction appears to have characteristic MRI features. Affected
tissue within the cerebellum is typically wedge-shaped with low signal intensity
in T1-weighted images, high signal intensity in T2-weighted images, subtle rim
enhancement without central contrast enhancement in T1 post-gadolinium, and
selectively hyperintense in fluid-attenuated inversion recovery images. Anatomic
regions serviced by rostral cerebellar arteries are affected. Vascular risk
factors as compared with reports in human literature are also discussed.”
A Practical Guide to Canine and Feline Neurology. Curtis W. Dewey. John Wiley & Sons; 2008; 4-6, 194-195. Quote: ""Breed-associated neurologic abnormalities of dogs and cats. ... Cavalier King Charles Spaniels ... Cerebellar infarct". pp. 4-6. “Cerebellar infarcts appear to be most common in small breed dogs, most notably the Cavalier King Charles Spaniel (CKCS). It has been postulated that this predisposition may be related to this breed's propensity to develop heart disease, inherited platelet abnormalities, or to local aberrations in regional arterial (e.b., basilar artery) blood flow due to caudal occipital malformation (COMS), which is common in the breed. ... In the author's experience, the combination of COMS and cerebellar infarct is common in the CKCS, whereas combinations involving cardiac disease and platelet abnormalities are not.”
Computed tomography diagnosis of eight dogs with brain infarction. AEH Paul, Z Lenard, CS Mansfield. Australian Vet J. Oct. 2010; 88(10): 374-380. Quote: “Objective: Medical records of eight dogs [two Cavalier King Charles Spaniels (CKCS)] presenting with acute onset of neurological signs and a diagnosis of brain infarction as determined by computed tomography (CT) imaging were reviewed. Results: Ischaemic infarction in the territory of the rostral cerebellar artery was identified in three spaniel-breed dogs. All cerebellar infarcts were non-haemorrhagic. Telencephalic infarcts were identified in five dogs, in the territories of the middle cerebral artery (2/5) and rostral cerebral artery (3/5). One of these dogs had an ischaemic infarction, but all other infarctions appeared haemorrhagic. All dogs were geriatric (≥8 years old), with concurrent medical conditions identified in six dogs. One dog was euthanased after diagnosis because of the severity of its neurological signs and one dog was euthanased as a result of associated renal disease 2 months after diagnosis. Six dogs were alive at least 1 year after diagnosis. Conclusions CT is useful in the diagnosis of cerebrovascular accident in dogs, which can present as a spectrum of images with early changes in attenuation and subtle mass effects detected after infarction. CT is particularly sensitive for detecting haemorrhagic infarction, but under-represent ischaemic and lacunar infarctions when compared with MRI.”
Clinical and topographic magnetic resonance imaging characteristics of suspected thalamic infarcts in 16 dogs. Rita Gonçalves, Inés Carrera, Laurent Garosi, Peter M. Smith, J. Fraser McConnell, and Jacques Penderis Vet J, April 2011, 188(1)39-43. Quote: “Sixteen dogs with acute-onset, non-progressive signs of brain dysfunction and magnetic resonance imaging (MRI) characteristics compatible with thalamic infarction are described. ... There were 3 Cavalier King Charles spaniels (CKCS) ... Topographically the MRI lesions could be grouped in three thalamic regions, namely, paramedian (8/16), extensive dorsal (5/16) and ventrolateral (3/16). Paramedian lesions resulted in signs typical of vestibular dysfunction. Extensive dorsal lesions were associated with vestibular ataxia, circling and contralateral menace response deficits. Ventrolateral lesions resulted in circling and contralateral proprioceptive deficits. In several dogs, regions other than the thalamus were also affected: four extended into the midbrain; six extended to the internal capsule, and two dogs had a second lesion in the cerebellum. Three clinical syndromes were identified in association with thalamic infarction. These signs varied somewhat, most likely because lesions were not confined to specific nuclear boundaries and involved different combinations of thalamic nuclei."
