Volume 6 | Issue 1 (January 2004)


Veterinary Neurology and Neurosurgery Journal (VNNJ) Case Study 10

Vet Neurol Neurosurg J. January 2004;6(1):1.
Veterinary Neurology and Neurosurgery Journal (VNNJ)

Full Text Article (What's Your Diagnosis?)

March 2004

Presented by: Angel Hernández Guerra and Carmen Lorente-Méndez, University Cardinal Herrera CEU, Moncada, Valencia, Spain

Signalment, History, Physical Examination   Neurological Examination   Tests Performed   Case Summary

Signalment, History, Physical Examination

This dog was seen at the Veterinary Medical Teaching Hospital, Universidad Cardinal Herrera-CEU, Moncada, Valencia, Spain. We are grateful for the skillful participation of the Radiology Service and Clinical Laboratories in the diagnostic investigations of this dog.

 Signalment: Rough Collie, male, age unknown.

 History: The dog was referred to our hospital with a previous history of ataxia. It had been found a week earlier close to a busy road and was taken to a local animal shelter. The referring veterinarian suspected a traumatic origin of the clinical signs.

 Medications: None

Physical examination

 General: Depressed and dull. Body condition score=3 (System range= 1-9)

 Rectal temperature: 38.0. Heart rate: 100/min, normal rhythm, femoral artery pulses equal and synchronous. Respiratory rate+ 24/m. Mucosae pale, capillary refill time < 2 sec

 Integument: Normal

 Musculoskeletal: mild muscle atrophy of the entire body

 Lymph nodes: N

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Neurological Examination

 Consciousness: Slightly obtunded.

 Falling: Absent

 Head Tilt: None

 Tremor: None

 Muscle tone: reduced in thoracic limbs.

 Gait: See video   Watch the Video

 Circling: None observed

 Paresis: Not apparent.

Postural and Placing Reactions

 Conscious proprioception: See video  Watch the Video

 "Paper Test" - Thoracic and pelvic limbs: See video  Watch the Video

 "Knuckling"- Thoracic limbs: Left: slow / Right: normal; Pelvic Limbs: Left very slow Right: normal

 Visual and tactile placing: Thoracic limbs: unable to evaluate; Pelvic limbs: unable to evaluate

 Hopping: - Thoracic limbs: slow Pelvic limbs: slow

 Hemistand/walk: dog would fall

 Wheelbarrowing: Thoracic limbs: slow Pelvic limbs:
See video  Watch the Video

 Extensor thrust: slow

Spinal (Segmental) Reflexes: (N=normal; D= depressed; A= Absent; I= increased)

 Tendon Reflexes: Forelimb: Extensor Carpi: D: Biceps brachii: Not evaluated; Triceps brachii: Not evaluated

 Pelvic limbs: Quadriceps: N; Gastroc / Dig. Flexors: N.

 Flexion Reflexes: Forelimbs: D; Pelvic limbs: I.

 Crossed Extensor Reflexes: Forelimbs: Not present clinically; Pelvic limbs: Not present clinically.

 Perineal Reflexes: N

 Cutaneous Trunci Reflexes: Present in all normal segmental levels.

 Pain Perception In Limbs: See video  Watch the Video

Cranial Nerves

 I: Not tested

 II: Vision apparently normal.

 III, IV, VI: Pupils equal, normal direct and indirect pupillary light reflexes. Normal ocular positions and physiological nystagmus

 V: Sensory: N Motor: N.

 VII: Sensory: N; Muscles of facial expression N;

 VIII: Righting reactions: N; Spontaneous nystagmus: absent; Positional nystagmus: absent.

 VII: Vision menace - Nystagmus, resting VIII - Nystagmus

 IX, X: Gag reflex- normal and symmetrical.

 XII: Tongue: normal position, symmetry, normal movements.

Ocular fundus: retinal bleeding, no other signs of uveal inflammation, (Intraocular pressure, Tyndall, etc)

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Tests Performed

Hematology, Chemistry and Urinalysis

Clinical Chemistry Results

Constituent

Patient's Results

Units

Reference Range (Dog)

Alk. Phosphatase

56

U/L

15-127 U/L

ALT (SGPT)

33

U/L

19-70

AST (SGOT)

8

U/L

15-43

Bilirubin: total

< 0.1

mg/dl

0-0.4

Blood urea nitrogen (BUN)

7,5

mg/dl

8-31

Calcium

Not done

mg/dl

9.9-11.4

Phosphorus, inorganic

Not done

mg/dl

3.0-6.2

Cholesterol

245

mg/dl

135-345

Creatine kinase

not done

U/L

46-320

Creatinine

1.19

mg/dl

0.8-1.6

Electrolytes:

Anion gap

Not done

 

12-25

Chloride

120.6

mmol/l

105-116

CO2, total

Not done

mmol/l

16-26

Potassium

4.2.

mmol/l

4.1-5.3

Sodium

154.5

mmol/l

145-154

Total protein

6.8

g/dl

5.4-7.4

Albumin

2.83

g/dl

2.9-4.2

Hemogram Results

Parameter

Patient's results

Reference Values (Dog)

Erythrocytes

5.01

5.5-8.5 million

Haemoglobin (Hb)

12.7

12.0-18.0 g/dl

Hematocrit

43.1

37-55%

Mean corpuscular volume

87.4

62-77 fl

Mean corpusc. Hb

25.3

33-37 g/d

Mean corpusc. Hb conc.

29

21.5-26.5 pg

Reticulocytes

not done

0.5-1 %

Leukocytes

7010

6000-17000/microliter

Band

0

0-300/microliter

Neutrophils

5467

3000-11500/microliter

Lymphocytes

821

1000-4800/microliter

Monocytes

560

150-1350/microliter

Eosinophils

140

100-1250/microliter

Basophils

0

Rare

Platelets

217

200-500x1000

Icteric Index

Not done.

2.0-5.0

Plasma proteins

6.8

6.0-8.0

Fibrinogen

Not done

200-400 mg/dl

Protein:fibrinogen

Not done

 

Immunology, Serology and Microbiology

Neosporosis Serology: Neospora caninum: negative

Vector-borne Diseases, Serology:
Serology for
Ehrlichia canis: 1:1280 (positive)
Ehrlichia platys: Negative

Toxoplasmosis, Serology:
Serology for Toxoplasma gondii: Negative

Canine Distemper, Serology:
Canine distemper virus:negative

Cryptococcal Serology: Cryptococcus neoformans: negative

Cerebrospinal Fluid: Total and Differential Cell Counts; Total Protein

 Fluid from: Cerebello-medullary cistern
Gross appearance: Hazy, colourless
Refractive index: Not done

 Total Protein: 200 mg/dl; Pandy test 2+
Total erythrocytes: 100/µL
Total nucleated cells: 120/µL

Differential Nucleated Cell Counts:

 Neutrophils: 45%
Small mononuclear cells: 0%
Large mononuclear cells: 7%
Eosinophils: 48%

Imaging

Radiographs - Survey Film and Myelogram

Click on an image to see a larger view
Click to view larger image
 

Lateral cervicothoracic radiograph

Click to view larger image
 

Lateral cervicothoracic myelogram

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Case Summary

Angel Maria Hernadex-Guerra, Carmen Lorente-Mendez
Departamento de Medicina y Cirugía Animal. Universidad Cardenal Herrera-CEU.
Avenida Seminario s/n. Moncada, Valencia, Spain

Cervicothoracic Spinal Cord Syndrome associated with Ehrlichia canis.

Summary and Diagnosis

A Rough Collie dog referred to our hospital with a previous history of ataxia is described here. The dog had been found a week before close to a busy road and taken to a local animal shelter. The referring veterinarian suspected a traumatic origin of the clinical signs. Our physical examination revealed a mildly lethargic and ataxic dog. Neurological examination revealed a cervicothoracic spinal cord syndrome, with lower motor neuron signs in the fore legs and upper motor neuron signs in the rear legs. Plain X-rays of the caudal cervical area appeared to show a decreased C6-C7 intervertebral space, consistent with the neurological examination. However, no abnormality was found on myelography. CSF taken at the time of myelography presented changes typical of meningitis/meningoencephalitis. Indirect immunofluorescence of the CSF was positive for E.canis.

Although described, meningitis is not a typical presentation of E.canis, nor is E.canis a typical cause of meningitis. In addition, meningitis is often regarded as causing multifocal signs; however, this case presented signs compatible with a focal lesion.

Treatment and Follow-up.

Imidocarb dipropionate, subcutaneous, twice, with 14 days in between.

Great improvement 5 days after the first injection; completely recovery a week after the second imidocarb dipropionate injection.

Discussion

Meningitis is inflammation of the meninges1, and usually is accompanied by encephalitis.2 Traditionally, it has been considered to have multifocal neurological signs1,3; however, in a study done by Tipold in 1995 in Switzerland, two thirds of the dogs with proven meningitis were presented with signs of focal rather than multifocal neurological lesion. The same study showed that clinical signs (both systemic and neurological) of meningitis are rather unspecific regardless of the aetiology, rendering the diagnosis of meningitis/meningoencephalitis very difficult.1

When there are clinical signs and results of ancillary diagnostic tests2,3, especially CSF analysis, are consistent with meningitis/meningoencephalitis, several causes of inflammatory disease of the CNS must be ruled out. The differential diagnosis in south west Europe should include Toxoplasma gondii, Neospora caninum, Rickettsia rickettsii, Ehrlichia canis, Cryptococcus neoformans,, distemper virus infection meningitis and idiopathic inflammatory disorders like granulomatous meningoencephalomyelitis, and steroid responsive meningitis-arteritis. Therefore a CSF analysis is essential to reach a diagnosis. This analysis should include, WBC count and differential, protein content and serology.1 Other possible tests are culture and sensitivity and immunoglobulin-G ratio. Ancillary tests that may be useful include computerized tomography, magnetic resonance imaging, and brain biopsy.1

In this case, having a CSF analysis consistent with an inflammatory/infectious process, serology of the CSF for the most common infectious causes of this area was performed. A positive titer was obtained confirming a diagnosis of ehrlichiosis.

The detection of antibodies against E. canis is considered of high specificity and sensitivity. Either serum or CSF can be tested for antibody by indirect fluorescence assay. A titer of 1:10 or greater with the indirect fluorescent assay test is considered positive. The test may be negative early in the disease.4,5

E. canis is a tick-borne intracellular bacterium in the family Ehrlichiaceae.4,6 It is transmitted to dogs by the brown dog tick Rhipicephalus sanguineus.4,5 CNS lesions are characterized by a lymphoplasmacytic meningoencephalitis involving the meninges, cerebral cortex and brainstem.5 After a variable incubation phase, the disease may go through three described stages: an acute one that usually lasts two to four weeks with non-specific signs, followed by a subclinical phase, and a third phase with more severe symptoms. Neurological signs appear in the latter phase.4

It is uncommon for dogs suffering the disease to present neurological signs, notwithstanding that E. canis has been associated with several neurological syndromes.4,5,8 Neurological signs result from organism-induced vasculitis, the host immune response and the haemorrhagic diathesis.3 These signs would include seizures, vestibular dysfunction, lower motoneuron disease and meningitis, as in this case.4,8

Dogs suffering canine monocytic ehrlichiosis presenting neurological disease usually show as well systemic signs such as fever, ophthalmic abnormalities, pale mucosae, respiratory signs.4,7,8,9 Non-neurological signs are usually enough for the clinician to suspect the disease, especially in areas with high prevalence of the disease. The diagnosis is usually confirmed by finding positive E. canis serum titers.4,8,9

The treatment of choice is either doxycycline (at 10 - 20 mg/kg, PO bid), or imidocarb dipropionate (5-7 mg, SC or IM; 2 injections, 2 weeks apart), both with very good results.4,5,8,9 The choice of treatment depends on the specific case; Doxycycline is usually first choice in house-kept dogs, whereas imidocarb dipropionate, that requires two painful injections, is applied in cases where daily administration is impracticable or inconvenient.

References

1.  Tipold A. (1995). Diagnosis of inflammatory and infectious disease of the central nervous system in Dogs: a retrospective study. Journal of Veterinary Internal Medicine. Vol 9, no 5, 304-314

2.  Bagley RS (1995). Diseases of the brain. In: Manual of Small Animal Neurology. Second edition. Pg: 112-124. Ed: British Small Animal Association. Cheltenham, Gloucestershire. UK

3.  Muñana KR (1996). Encephalitis and Meningitis. Veterinary Clinics of North America. Vol. 26, No 4, 857-873.

4.  Sainz A, Carmona A, Tesouro MA, (2001). Ehrlichiosis, Patogenia y Cuadro Clínico. Canis y Felis. Vol 51, pp: 25-40

5.  Carter GR. (2003). Major Infectious Diseases of Dogs and Cats. In: V In: A concise guide to infectious and Parasitic Diseases of Dogs and Cats International Veterinary Information Service, Ithaca NY (www.ivis.org), 2003; B0405.0403

6.  Taxonomic outline of the prokaryotic genera. Bergey's Manual of Systematic Bacteriology. Second edition, April 2001.

7.  Davidson MG, Breitschwerdt EB, Nasisse MP, et al (1989). Ocular manifestations of Rocky Mountain spotted fever in dogs. J Am Vet Med Assoc; 194:777-781. 

8.  Braund KG (2002) Inflammatory Diseases of the Central Nervous System. En: Clinical Neurology in Small Animals - Localization, Diagnosis and treatment. International Veterinary Information Service (www. ivis.org) Ithaca, New York, USA.

9.  Hibler SC, Hoskins JD, Greene CE. Rickettsial infections in dogs: part II. Ehrlichiosis and infectious cyclic thrombocytopenia. Compendium Continuing Education Practice Veterinary, 8, 106-114.

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