Inflammation of the central nervous system is a common cause of neurological manifestation in dogs. The confirmation of an inflammatory origin is made by cerebrospinal fluid (CSF) analysis. However, a tentative diagnosis and a prognosis are not always easy to give when the results of complementary tests are pending. The signalment, history, clinical and CSF findings of 90 dogs presenting confirmed inflammation of the central nervous system were reviewed. Our goal was to determine if a consensus was found among these parameters to be able to direct the diagnosis and the prognosis.

Materials and Methods

The medical records of 90 dogs admitted to the Clinique Fregis,Arcueil-France, between 1999 and 2001 were retrospectively reviewed. On all dogs CSF result had revealed a pleocytose of more than 10 cells per microliter. Case histories, signalment, general and neurological examination results, results of CSF analysis, other complementary exams (blood work, serology, PCR, CSF electrophoresis, radiography, myelography, tomodensitometry and histopathology), and outcomes were reviewed. CSF tap was performed directly at the level of the cerebro-medullary cistern if an inflammatory central nervous system disease was suspected. The CSF tap was performed at the lumbar region during the myelographic procedure if a medullary problem was suspected. Cell count was performed in house within a few minutes after collection; protein measurement and electrophoresis were performed within 48 hours on centrifuged specimen and cell differential count after cytospin. Serology titers were performed in veterinary labs with validated techniques. Radiographs and myelography were performed in house and tomodensitometry studies at two veterinary imaging centers. The follow up was performed either during control visits, either on phone with the referring veterinarian or the owner.

SIGNALMENT and history

Twelve of the 90 dogs were Boxer (14%), 9 were Yorkshire Terriers (10%), 7 were Poodle or West Highland White Terrier (8%). 26 pure breed were represented just once and mix breed, 4 times. The incidence of Boxer presentation in our clinic is 1 for 43 case; The incidence of Boxer presentation in this study is 1 for 7,5 cases. Twenty of the 90 dogs were less than 1-year-old (22%), 13 less than 2 (14%) and 7 more than 8 years old (8%). Forty-three of the 90 dogs were intact females (49%) and 40 were intact males (44%). Sixty-one dogs had no history of general signs (65%), 21 had hyperthermia (22%) and 8 had prostration (9%).

Major owner complain

On neurological examination, 21 had difficulty walking (24%), 13 had ataxia (15%), 8 had neck pain, 8 had diffused pain (10%) 6 had either amaurosis, seizures or other deficits (7%). Twenty-six dogs had clinical signs duration of less than a week (30%), 37 had clinical signs for 1 to 4 weeks (43%) and 23 had clinical signs for more than one month (27%). Owner's complain was not available on 4 cases.

Results of neurological examination

Sixty-four dogs had conscious proprioception deficit (71%). Thirty-seven dogs had cranial nerve deficits (41%); among them, 22 had menace deficit, 12 had pupillary light abnormalities and 12 had vestibular signs, some of them having more than one deficit.

CSF analysis

Sixty-nine CSF tap were performed at the level of the cerebro-medullary cistern. CSF analysis revealed a nucleated cell count between 10 to 30 in 23 dogs (25%), 30 to 50 in 10 dogs (11%), 50 to 100 in 16 dogs (18%), 100 to 1000 in 25 dogs (27%) and more than 1000 in 17 dogs (19%). Total protein concentration in CSF was less than 0,3 g/l in 8 dogs (9%), in between 0,3 and 1 g/l in 32 dogs (35%), in between 1 and 3 in 39 dogs (43%) and above 3 g/l in 12 dogs (13%). Thirty-six dogs had a CSF differential mainly mononucleated (57%), 14 had a mixed population (22%) and 13 had a mainly polynucleated population (21%).

Complementary blood work

When blood cont was performed, a normal result was found in 18 dogs (41%), a neutrophilia in 22 dogs (50%) and a leucopenia in 4 dogs (9%).

Tentative diagnosis at discharge

Eighteen dogs had a tentative diagnosis of meningitis at discharge (20%); 5 of meningo-encephalitis (6%), 33 of meningo-myelitis (36%), 29 of meningo-encephalo-myelitis (32%). 5 had a compressive cord lesion (6%).

Discussion

By the time of writing of this proceeding, the retrospective study is being continued with analysis of the follow up, the final diagnosis and a review of all the parameters according to the breed or the size of dogs and their age. The actual subjective impression is that suppurative non-infectious meningitis is more common in large juvenile breed of dog with CSF results being peculiar; cure is obtained within a few months. The tentative diagnosis is easily made before the results are pending. This must be opposed to the small breed, young adult dogs with a mix pleocytosis which reach more often remission than cure. Those cannot be diagnosed until all the complementary results are back. A lot of inflammatory central nervous system inflammation ends with no known etiology.