FDG‐PET IN HEALTHY AND EPILEPTIC LAGOTTO ROMAGNOLO DOGS AND CHANGES IN BRAIN GLUCOSE UPTAKE WITH AGE

Regional cerebral metabolism and blood flow can be measured noninvasively with positron emission tomography (PET). 2‐[¹⁸F]fluoro‐2‐deoxy‐D‐glucose (FDG) widely serves as a PET tracer in human patients with epilepsy to identify the seizure focus. The goal of this prospective study was to determine whether juvenile or adult dogs with focal‐onset epilepsy exhibit abnormal cerebral glucose uptake interictally and whether glucose uptake changes with age. We used FDG‐PET to examine six Lagotto Romagnolo dogs with juvenile epilepsy, two dogs with adult‐onset epilepsy, and five control dogs of the same breed at different ages. Three researchers unaware of dog clinical status visually analyzed co‐registered PET and magnetic resonance imaging (MRI) images. Results of the visual PET analyses were compared with electroencephalography (EEG) results. In semiquantitative analysis, relative standard uptake values (SUV) of regions of interest (ROI) drawn to different brain regions were compared between epileptic and control dogs. Visual analysis revealed areas of hypometabolism interictally in five out of six dogs with juvenile epilepsy in the occipital, temporal, and parietal cortex. Changes in EEG occurred in three of these dogs in the same areas where PET showed cortical hypometabolism. Visual analysis showed no abnormalities in cerebral glucose uptake in dogs with adult‐onset epilepsy. Semiquantitative analysis detected no differences between epileptic and control dogs. This result emphasizes the importance of visual analysis in FDG‐PET studies of epileptic dogs. A change in glucose uptake was also detected with age. Glucose uptake values increased between dog ages of 8 and 28 weeks and then remained constant.     

CEREBRAL GLUCOSE UTILIZATION MEASURED WITH HIGH RESOLUTION POSITRON EMISSION TOMOGRAPHY IN EPILEPTIC FINNISH SPITZ DOGS AND HEALTHY DOGS

In human epileptic patients, changes in cerebral glucose utilization can be detected 2‐deoxy‐2‐[¹⁸F] fluoro‐d ‐glucose positron emission tomography (FDG‐PET). The purpose of this prospective study was to determine whether epileptic dogs might show similar findings. Eleven Finnish Spitz dogs with focal idiopathic epilepsy and six healthy dogs were included. Dogs were examined using electroencephalography (EEG) and FDG‐PET, with epileptic dogs being evaluated during the interictal period. Visual and semi‐quantitative assessment methods of FDG‐PET were compared and contrasted with EEG findings. Three independent observers, unaware of dog clinical status, detected FDG‐PET uptake abnormalities in 9/11 epileptic (82%), and 4/8 healthy dogs (50%). Occipital cortex findings were significantly associated with epileptic status (P = 0.013). Epileptic dogs had significantly lower standardized uptake values (SUVs) in numerous cortical regions, the cerebellum, and the hippocampus compared to the control dogs. The lowest SUVs were found in the occipital lobe. White matter normalized and left‐right asymmetry index values for all pairs of homologous regions did not differ between groups. Visual evaluation of the EEGs was less sensitive (36%) than FDG‐PET. Both diagnostic tests were consensual and specific (100%) for occipital findings, but EEG had a lower sensitivity for detecting lateralized foci than FDG‐PET. Findings supported the use of FDG‐PET as a diagnostic test for dogs with suspected idiopathic epilepsy. Visual and semiquantitative analyses of FDG‐PET scans provided complementary information. Findings also supported the theory that epileptogenesis may occur in multiple brain regions in Finnish Spitz dogs with idiopathic epilepsy.     

Electroencephalography findings in healthy and Finnish Spitz dogs with epilepsy: visual and background quantitative analysis

BACKGROUND: Qualitative and quantitative electroencephalography (EEG) parameters of healthy and Finnish Spitz dogs with epilepsy have not been determined. OBJECTIVE: To determine if EEG can provide specific characteristics to distinguish between healthy dogs and dogs with epilepsy. ANIMALS: Sixteen healthy and 15 Finnish Spitz dogs with epilepsy. METHODS: A prospective clinical EEG study performed under medetomidine sedation. Blinded visual and quantitative EEG analyses were performed and results were compared between study groups. RESULTS: Benign epileptiform transients of sleep and sleep spindles were a frequent finding in a majority of animals from both groups. The EEG analysis detected epileptiform activity in 3 Finnish Spitz dogs with epilepsy and in 1 healthy Finnish Spitz dog. Epileptiform activity was characterized by spikes, polyspikes, and spike slow wave complexes in posterior-occipital derivation in dogs with epilepsy and with midline spikes in control dog. The healthy dogs showed significantly less theta and beta activity than did the dogs with epilepsy (P < .01), but the only significant difference between healthy dogs and dogs with untreated epilepsy was in the alpha band (P < .001). Phenobarbital treatment increased alpha, beta (P < .001), and theta (P < .01), and decreased delta (P < .001) frequency bands compared with dogs with untreated epilepsy. CONCLUSIONS AND CLINICAL IMPORTANCE: Benign epileptiform transients of sleep could be easily misinterpreted as epileptiform activity. Epileptiform activity in Finnish Spitz dogs with epilepsy seems to originate from a posterior-occipital location. The EEG of dogs with epilepsy exhibited a significant difference in background frequency bands compared with the control dogs. Phenobarbital treatment markedly influenced all background activity bands. Quantitative EEG analysis, in addition to visual analysis, seems to be a useful tool in the examination of patients with epilepsy.     

Magnetic resonance imaging findings in Finnish Spitz dogs with focal epilepsy

Eleven Finnish Spitz dogs with focal seizures and 3 healthy controls were evaluated. General clinical and neurological examinations, blood examination, urinalysis, cerebrospinal fluid examination, electroencephalography (EEG), and magnetic resonance imaging (MRI) of the brain were performed on all dogs. On EEG examination, focal epileptic activity was found in 7 of 11 dogs (64%), and generalized epileptic activity was observed in 4 of 11 dogs (36%). MRI (performed with 1.5 T equipment) detected changes in 1 epileptic dog. Mild contrast enhancement after gadolinium injection was identified in this dog's right parietal cortex. However, no such changes were observed in repeated magnetic resonance images. Special emphasis was given to seizure history to determine any correlations between seizure intervals and MRI findings. Our results indicate that Finnish Spitz dogs with focal seizures suffer from focal idiopathic epilepsy and have nondetectable findings on MRI or pathology. MRI showed poor sensitivity in detecting epileptogenic areas in our patients with focal seizures. Reversible MRI changes in 1 dog could have been caused by seizures.     

Cerebellar cortical abiotrophy in Lagotto Romagnolo dogs

This case report documents two pathological variations of potentially inherited, cerebellar cortical abiotrophy in two unrelated Lagotto Romagnolo breed dogs. The first dog had an atypical lesion in the cerebellar cortex with depletion of cerebellar granular cell layer and sparing of the Purkinje cell layer. The second case had degenerative changes in both Purkinje and granular cell layers. The clinical picture was similar in both cases presented, although the severity of the signs of cerebellar dysfunction varied.     

Benign familial juvenile epilepsy in Lagotto Romagnolo dogs

BACKGROUND: Idiopathic childhood epilepsies with benign outcomes are well recognized in human medicine, but are not reported in veterinary literature. We recognized such a neurologic syndrome in Lagotto Romagnolo dogs. ANIMALS: Twenty-five Lagotto Romagnolo puppies from 9 different litters examined because of simple or complex focal seizures and 3 adult Lagotto Romagnolo dogs exhibiting similar clinical signs were used. METHODS: Clinical and diagnostic evaluations of affected dogs were conducted, including electromyography, electroencephalography, and other testing. RESULTS: Seizures in puppies began at 5 to 9 weeks of age and usually resolved spontaneously by 8 to 13 weeks. Those with the most severe seizures also had signs of neurologic disease between these seizures, including generalized ataxia and hypermetria. There were no abnormalities in routine laboratory screenings of blood, urine, and cerebrospinal fluid. Electromyography, brainstem auditory-evoked potentials, and magnetic resonance imaging revealed no specific and consistent abnormalities. Fourteen of 16 (87.5%) affected puppies and 2 of 3 (67%) adult dogs revealed epileptiform activity in the electroencephalogram. Histopathologic examination in 1 puppy and 1 adult dog revealed lesions of Purkinje cell inclusions and vacuolation of their axons restricted to the cerebellum. Pedigree analysis suggests an autosomal recessive mode of inheritance. CONCLUSIONS AND CLINICAL IMPORTANCE: This disorder, with simple or complex focal seizures and cerebellar lesions, represents a newly recognized epileptic syndrome in dogs.