CENTRAL VESTIBULAR DISEASE IN A GERMAN SHEPHERD DOG

Neetu Saini1, Praveen V. Mathapati2, Sujata Turkar1, S.K. Uppal3 and Dipak Deka
1Assistant Professor, 2M.V.Sc. Student, 3Professor & Head; Department of Veterinary Medicine. College of Veterinay
& Animal Science, Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana, Punjab.
[Received: 14.6.2018; Accepted: 14.1.2019]
{DOI 10.29005/IJCP.2019.11.1.018-020}

An eight year old German shepherd bitch was presented with history of fever, head tilt and vomiting. Animal
was unable to balance with signs of incoordination, falling, proprioceptive deficits and nystagmus. Hematological
examination revealed severe neutrophilic leukocytosis. Biochemical parameters of LFT and RFT were within normal
range. Radiography of skull revealed normal air density in both ear canals and tympanic bullae. Thyroid function test
were within the normal range. Reverse transcriptase PCR for Canine distemper virus was positive. The animal was
treated with antibiotics and vestibule sedative drugs. The animal was clinically improved, however head tilt persists
even two months after the treatment. Based upon history, clinical signs and diagnostic tests, it was concluded that
Canine Distemper Virus (CDV) was responsible for Central Vestibular Disease (CVD) in present case.
Keywords: Central vestibular disease (CDV), Dog, Neurological, Neutrophilic leukocytosis.

Neurological disorders affecting vestibular system are commonly found in small animal practice. Vestibular system is the main component of nervous system responsible for maintaining balance, coordinated head movements, trunk and limbs (Chaves et al., 2014). The clinical signs associated with central or peripheral vestibular dysfunctions include head tilt, loss of balance, circling, falling, rolling, ataxia and abnormal eye movements (Nelson and
Couto, 2014). Neurological examination findings help to differentiate lesions of central vestibular system (CVS) from peripheral vestibular system (Kent et al., 2010) by absence or decrease of postural reactions, altered consciousness level and vertical nystagmus (De Lahunta and Glass, 2009). Inflammatory/ infectious diseases mainly canine distemper are commonly associated with central vestibular diseases in dogs (Kent et al., 2010). This case report presents diagnosis and therapeutic management of  central vestibular disease in a German shepherd dog.

Case History and Observations
A 8 year old German shepherd bitch weighing 25 kg was presented to Teaching Veterinary Hospital, College of Veteinary & Animal Science, Guru Angad Dev Veterinary and Animal Sciences University (GADVASU), Ludhiana with the history of fever, head tilt (Fig.1)

and vomiting. On clinical examination, dog was depressed, recumbent with high rectal temperature (104°F), congested mucous membranes and dyspnea. Head was tilted towards left side with ear pointing towards
the ground. The dog showed signs of incoordination, falling, proprioceptive deficits on the same side of head tilt and vertical nystagmus. There were no deficits of cranial nerves and no purulent discharge from ear canals. Palpation of the osseous bullae and temporo-mandibular joint did not reveal any pain or asymmetry.
Blood investigations showed significant leukocytosis (Total leukocyte count=68,320/μl; reference range, 5,000-
14,100/μl) with neutrophilia (62,854/μl; reference range, 5000-14100/μl). Platelet count was slightly low (1.51 x 105/μl; reference range, 2.1-6.2 x 105/μl). Biochemical analysis revealed normal liver function test (LFT) and renal function tests (RFT). Thyroid function tests i.e. Total T4 andTSH were within the normal range.

Radiography of skull revealed normal air density in both ear canals and tympanic bullae. The bone density of the skull was slightly reduced. Lateral chest radiograph revealed normal heart size, increased radioopacity in caudo-dorsal and cranial lung lobes. In Ventro-dorsal (VD) view, all the right and left lung lobes have increased radioopacity indicating presence of pulmonary edema. A 6-lead ECG recording revealed normal sinus rhythm with heart rate 100 bpm. Nasal and ocular samples were collected to run Reverse transcriptase- polymerase chain
reaction (RT-PCR) to rule out canine distemper and it was found positive. RT-PCR was carried out using N gene based primers where the positive sample showed 407bp amplification similar to the positive control. So based upon history, clinical signs and diagnostic tests, it was concluded that Canine distemper virus was responsible for
central vestibular signs in the present case.

Treatment and Discussion
The patient was empirically treated with Cefotaxime (25mg/kg I/M every 12 hourly) and Enrofloxacin (7mg/kg IM every 12 hourly) for 2 weeks to treat secondary bacterial infection. Normal saline @ 20 ml/kg b.wt. I/V every 12 hourly was given for 4 days to treat dehydration. The vomiting in this dog was controlled with vestibulosedative drug meclizine (1mg/kg, every 24 hourly) for 3 days. The animal showed significant improvement in clinical
condition after 2 weeks of treatment. The secondary bacterial infection was controlled with total leukocyte count (20,270/μl) and neutrophil count (18,243/μl). However, the head tilt persisted even after two months of
treatment.

The clinical features of vestibular dysfunctions are abnormalities of the gait, head, body and limb posture and eye
movements as also reported by De Lahunta and Glass (2009). However, vomiting and nausea are also occasionally present as mentioned by Chaves et al. (2014) also. The clinical signs of head tilt, ataxia, altered postural reaction i.e. proprioceptive deficits, altered level of consciousness confirms central vestibular disease in present case.
Propioceptive deficits are related to brain stem lesions and are consistent with central vestibular disease as also reported by Kent et al. (2010) and Troxel et al. (2005). The paresis of limbs as seen in present case was
could be due to the injury to upper motor neuron pathways that project through brain stem indicating central vestibular syndrome. In present study, the dog was completely non ambulatory showing tetraparesis which
cannot occur in dogs with peripheral vestibular disease, so confirming CVD as also recorded by Troxel et al. (2005).
Radiographic examination of tympanic bullaedid not reveal any abnormality in ears, so  ruling out ear infection (otitis). Signs of altered mentation and depression present in this case could be due to defect in reticular
activator system located in brain stem resulting due to CVD. Inflammatory/ infectious diseases mainly Canine distemper involving the central nervous system are most frequently associated with signs of vestibular
disease as also reported by Chaves et al. (2014). Higgins et al. (2006) reported that central vestibular dysfunctions have also found to be sequelae of hypothyroidism in dogs. Contrary to that, in present case, the thyroid function tests were normal so excluding possibility of hypothyroidism. Haematological examination revealed
neutrophilic leucocytosis in the present case which could be associated with secondary bacterial complications such as pneumonia due to canine distemper as also mentioned by Sherding (2006). Radiology of chest may
demonstrate an interstitial (viral) pneumonia in early cases and an alveolar pattern with bacterial pneumonia as observed in present case may occur later in the course of canine distemper disease. The vestibule sedative
drug meclizine was given for one week to alleviate emesis as recommended by Nelson and Couto (2014) also. So, based on history of sudden development of left sided head tilt with tight circling on the same side, absence
of any lesion or infection in the ear, exclusion of other diseases, absence of any radiological evidence of involvement of tympanicbullae and bony labrinth, altered mentation, proprioceptive deficits, vertical nystagmus in
the 8 year old dog appeared due to Central vestibular disease.

References
Chaves, R,O., Beckmann, D.V., Copat, B., Souza, F.W., Fabretti, A.K., Gomes, L.A., Fighera, R.A. and Mazzanti, A. (2014).Vestibular disease in dogs: 81 cases (2006-2013) Pesq. Vet. Bras., 34 (12): 1229-1233.

De Lahunta, A. and Glass, E. (2009). Vestibular system: special proprioception. In: Ibid. (Ed.), Veterinary Neuroanatomy and Clinical Neurolo-gy. 3rd edn., Saunders Elsevier, St. Louis, U.S.A. Pp. 319-347.

Higgins, M.A., Rossmeisl, J.H. and Panciera, D.L. (2006). Hypothyroid associated central vestibular disease in ten dogs: 1999–2005. J. Vet. Intern. Med., 20: 1363–1369.

Kent, M., Platt, S.R. and Schatzberg, S.J. (2010). The neurology of balance: Function and dysfunction of the vestibular system in dogs and cats. Vet. J., 185: 247- 258.

Nelson, R.W. and Couto, C.G. (2014). Small Animal Internal Medicine. 5thedn. C.G. Mosby, St. Louis, U.S.A. Pp. 1028-1035.

Sherding, R.G. (2006). Canine Distemper. In: Birchard, S.J. and Sherding, R.G. (Eds.). Saunders manual of small animal practice. 3rd edn., Saunders, Philadelphia,U.S.A. Pp. 154-157.

Troxel, M., Drobatz, K. and Vite, C. (2005). Signs of neurologic dysfunction in dogs with central versus peripheral vestibular disease. J. Am. Vet. Med. Assoc., 227: 570-574.

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