Frequency of non-generalized tonic clonic seizures in a referral population of dogs

Absence seizures are a type of generalized onset seizure associated in humans with brief activity interruptions, unresponsiveness and staring. Absence seizures are infrequently reported in veterinary patients, visually indistinguishable from focal seizures, and so may be grouped as non-generalized tonic clonic seizures (non-GTCS). The objective of this retrospective study was to provide a preliminary understanding of the frequency of non-GTCS in dogs and estimate its prevalence by evaluating the distribution of seizure types presented to a referral hospital over 4 years (May 2017-April 2021), as determined from the medical record history and electroencephalography (EEG) diagnostic testing where available. A total of 528 cases were included via a medical record search for dogs with epilepsy and/or seizures presented to the neurology or emergency services. Cases were categorized into seizure types based on reported clinical signs. Each year, 53-63 % of seizure cases were described as generalized tonic clonic seizures (GTCS), 9-15 % GTCS with additional events and 29-35 % suspected non-GTCS. EEG confirmed absence seizures in 12 of 44 EEGs, 5 cases having a history of GTCS and seven without prior GTCS. This preliminary study suggests that non-GTCS may be relatively common as one third of seizure cases in the referral population presented with non-GTCS clinical signs. Prospective studies using EEG are merited to definitively determine the prevalence of these different seizure types in dogs. Acknowledging the impact of these seizures will improve awareness, aiding veterinarians in their recognition, diagnosis and potential treatment options.

Juvenile idiopathic epilepsy in Egyptian Arabian foals: 22 cases (1985-2005)

BACKGROUND

Epilepsy is relatively uncommon in horses compared with other species and limited information is available.

HYPOTHESIS

The objectives of the study were to describe the age of onset, clinical signs, clinicopathologic data, electroeticephalographic findings, treatment, and outcome, including long-term prognosis in Arabian foals with idiopathic epilepsy.

ANIMALS

Twenty-two foals were included in the study.

MATERIALS AND METHODS

Medical records from 1985 to 2005 were reviewed.

RESULTS

The age of onset of affected foals ranged from 2 days to 6 months. Seizures were characterized by generalized tonic and clonic motor activity, staring, and loss of consciousness. The most common postictal signs were transient blindness and abnormal mental status. The interictal neurologic examination was otherwise normal. Clinicopathologic data and imaging diagnostics were normal except in 4 foals that developed complications. Electroencephalography revealed epileptiform activity in 9 of 13 foals. Foals were treated with benzodiazepines for the short-term; whereas phenobarbital was used over the long-term. Potassium bromide was added in 3 foals in which seizures were multiple, frequent, and difficult to control. The long-term prognosis was favorable with cessation of seizures by 1 year of age. The most common complication was head trauma. The most common concurrent disease was pneumonia.

CONCLUSIONS AND CLINICAL IMPORTANCE

Juvenile idiopathic epilepsy of Egyptian Arabian foals has an early clinical onset but appears to be self-limiting. Information obtained from this study strongly suggests a heritable condition that merits further investigation.

Clinical and genetic investigations of idiopathic epilepsy in the Bernese mountain dog

A study was conducted to investigate the clinical aspects and to define the mode of inheritance of idiopathic epilepsy in the Bernese mountain dog. Pedigree analyses were carried out on an open, non-preselected population of 4005 dogs. Five different subpopulations with 50 epileptic dogs from 13 generations were included. Almost all epileptic patients showed generalised seizures of the grand-mal type with a well-defined prodromal and postictal phase. The majority (62 per cent) of the epileptic dogs had had their first seizures at between one and three years of age and it was found that the age at first seizure was significantly (P < 0.05) lower in dogs from affected parental animals than in dogs from healthy parental animals. A clear predisposition for males was also noted. Additionally, there was no correlation between inbreeding coefficient and age at first seizure or incidence rate of seizures. The increased occurrence of the disease in different subpopulations and different families of the same sires or dams showed that there was a genetic basis for the condition in the Bernese mountain dog. Furthermore, the results of the pedigree analyses and binomial test support the hypothesis that idiopathic epilepsy has a polygenic, recessive mode of inheritance in the breed. Additional objective test-mating programmes would however be necessary to define the exact mode of inheritance.

A canine distemper virus epidemic in Serengeti lions (Panthera leo)

Canine distemper virus (CDV) is thought to have caused several fatal epidemics in canids within the Serengeti-Mara ecosystem of East Africa, affecting silver-backed jackals (Canis mesomelas) and bat-eared foxes (Otocyon megalotis) in 1978 (ref. 1), and African wild dogs (Lycaon pictus) in 1991 (refs 2, 3). The large, closely monitored Serengeti lion population was not affected in these epidemics. However, an epidemic caused by a morbillivirus closely related to CDV emerged abruptly in the lion population of the Serengeti National Park, Tanzania, in early 1994, resulting in fatal neurological disease characterized by grand mal seizures and myoclonus; the lions that died had encephalitis and pneumonia. Here we report the identification of CDV from these lions, and the close phylogenetic relationship between CDV isolates from lions and domestic dogs. By August 1994, 85% of the Serengeti lion population had anti-CDV antibodies, and the epidemic spread north to lions in the Maasai Mara National reserve, Kenya, and uncounted hyaenas, bat-eared foxes, and leopards were also affected.

Clinical pharmacokinetics of phenytoin in the dog: a reevaluation

The pharmacokinetics of phenytoin, as well as drug plasma concentrations, during continued treatment were studied in the dog. After IV injection of 10 mg/kg, the average elimination half-life was 4.4 hours, which is in good agreement with previous studies. Bioavailability from tablet formulation was rather poor (av 36% compared with that obtained with IV) and showed great variation between dogs. Even with the dosage regimen of 20 mg of drug/kg given TID orally, therapeutic plasma concentrations could only be maintained for the first 2 or 3 days of treatment; these subsequently decreased to ineffective concentrations during the 1st week of treatment. This effect was accompanied by considerable reductions in half-life, indicating that phenytoin is a strong inducer of microsomal drug metabolism in the dog. Phenytoin must be considered as poorly suited for the treatment of canine epilepsy.

Taurine treatment of spontaneous chronic epilepsy in a cat

Administration of taurine to a cat suffering from naturally occurring chronic (about 3 years) epilepsy caused disappearance of the clinical manifestation of the seizures as well as a marked improvement in the previously grossly abnormal EEG. The treatment consisted of injections of taurine initially, followed by a more prolonged administration of the amino acid by mouth. The combined methods of administration seemed essential for the success of the trial. To date (5 months post-taurine) the animal has suffered only one "grand mal" type seizure which occurred 3 months after the last dose of taurine was administered. Disappearance of the seizures preceded by several weeks the improvement in the EEG. In accordance with previous findings by a number of investigators, the results of this study suggest an immediate depressant action of taurine on hyperexcitable cortical neurons, followed by a more long-lasting, ameliorative influence on cerebral metabolism contributing to an increased resistance to epileptic discharge.