Some types of canine epilepsy have no cure, but it is possible to resort to a treatment that reduces seizures
- Author: By CAROLINA PINEDO
- Publication date: May 13, 2013
Dog epilepsy is a brain disease that in certain cases can be cured and in others considerably reduce the frequency of attacks. This article explains why some types of epilepsy in dogs have a cure and others do not, the importance of making a good diagnosis of canine epilepsy, what is your treatment and why now it is diagnosed more.
Can epilepsy in dogs be cured?
A dog's epilepsy can be caused by various reasons, including brain tumors and diseases related to the abnormal functioning of the thyroid.
In these cases, the animal may suffer seizures similar to epileptic seizures, but once the veterinarian treats the cause that causes it, the symptoms disappear and therefore the dog has a cure.
In the case where seizures do not have their origin in a certain pathologyLike a brain tumor, the diagnosis of the convulsing can is another: idiopathic epilepsy. In this case, the disease is chronic. It has no cure, but with proper treatment, the frequency of epileptic seizures can be reduced considerably.
Less than 10% of epileptic dogs stay two years without seizures
Less than 10% of epileptic dogs manage to stay two years without suffering attacks, says Paloma Toni, veterinarian and neurologist at the Veterinary Hospital of the Faculty of Veterinary Medicine of the Complutense University of Madrid. "Frequently the crises reappear and, if not, it cannot be assured that the animal will not suffer more attacks throughout its life," says Toni.
Epilepsy in dogs: determine the cause
Seizures of the dog are not always due to epilepsy, since they can have their origin in pathologies and metabolic disorders of the dog, including hypoglycemia.
However, there is no evidence that serves to diagnose canine epilepsy. Hence, the importance of determining the cause of the convulsive episodes of the animal, since if there is a pathology that causes canker seizures, a treatment that solves the situation can be applied.
Another case that can be raised with regard to dog seizures is that, once the veterinarian has performed all the relevant tests, such as cranial magnetic resonance and cerebrospinal fluid (brain) analysis, it is determined, by discard, that the convulsive episodes of the dog are caused by idiopathic or essential epilepsy.
This disease occurs due to a discharge of energy in the brain, which causes seizures in the dog. In this case, no abnormalities are detected in medical tests that could be the origin of the attacks. These are healthy dogs, but they "can have a genetic inheritance of epileptic ancestors", explains Javier Miner, veterinarian and neurologist. In this case it is a chronic epilepsy, which requires lifelong treatment for the dog.
Epilepsy in dogs: treatment
Scientists investigate new drugs for the treatment of canine epilepsy. The new pharmacological treatments are one of the novelties in the advances of the treatment to alleviate epilepsy in dogs. Zonisamide, levetiracetam and pregabalin are some names of the new medicines to treat this canine brain disease.
However, these drugs are expensive and, in many cases, do not appear to be more effective than phenobarbital or potassium bromide, the two medications most used in the treatment of idiopathic epilepsy, essential or true.
Currently, there is no medication effective enough, economically affordable and with few side effects to treat canine epilepsy. But scientists work to create new drugs that contribute to the effective treatment of canine idiopathic epilepsy.
Most of the Advances in research on canine epilepsy they have to do with the diagnosis of the causes of the crises. Magnetic resonances, the scanner and electroencephalograms are novel methods that facilitate the recognition of the causes that cause certain epilepsies. Therefore, more cases of so-called idiopathic or essential epilepsies are ruled out - when there is no pathology that causes seizures.
Tremors and absences in the epileptic dog
Seizures of epilepsy are characterized by a certain intensity and frequency. When the degree of the dog's seizures is slight, or translates into the trembling of a paw, it is a type of epilepsy that is characterized by having milder symptoms and is called tonic-clonic.
Other modalities of this type of epileptic seizures are absences: the dog is disconnected from the world or what experts call "the flycatcher" that throws dentelladas into the air, as if it wanted to catch an insect, or the one chases the tail compulsively.
This type of seizures and attitudes can lead to more frequent and more intense attacks over time, so if they are repeated, a specific treatment should be applied.
Canine epilepsy: why is it diagnosed more now?
Epilepsy is more frequent in certain races such as the can labrador, golden retriever, German shepherd, beagle and small dogs that are nervous, like the yorkshire. However, epileptic seizures can occur in any dog breed and in mongrel dogs.
The fact that the dogs, before boom urban, living in the rural environment further away from people made it difficult to detect the disease of epileptic diseases in them.
In addition, dogs were considered working animals and their health needs were not met as effectively as they are today. On the contrary, the close coexistence between owners and dogs on city floors has led to an increase in the diagnosis and treatment of animals with this cerebral pathology.
Objectives of antiepileptic treatment
The main objective of anti-epileptic treatment is to try to reduce the frequency of epileptiform seizures, their duration and intensity, associated with null or minimal side effects in order to maximize the quality of life of both the patient and the owners.
To achieve this goal it is necessary that clinical veterinarians know how to decide when to start treatment, what medications should be used and at what dose, know the possible complications and side effects, monitor the treatment and determine if the therapy can be stopped. at some point.
There is no consensus based on studies to decide when to start an antiepileptic treatment in veterinary medicine. As a general rule, all publications recommend initiating antiepileptic treatment when any of the following criteria is present:
- When there are two or more epileptosis crises in a period of six months.
- When the patient presents in a state of epilepsy or crisis in a run or cluster.
- When there is a very long posictal period (more than 24 hours) or it is severe (aggression, blindness, etc.).
- When the frequency or duration of epileptiform seizures increases.
There is also no consensus on the choice of antiepileptic in dogs. The choice of an antiepileptic is based on a series of factors related to the patient (tolerance, adverse effects, type of crisis) and also with respect to the owner (lifestyle, economic circumstances). Next, the currently available antiepileptic drugs are listed, their pharmacology and mechanism of action, adverse effects, doses and monitoring are described. The main characteristics and details of each antiepileptic drug are summarized in the table.
It is a drug belonging to the group of barbiturates and is the oldest antiepileptic used in veterinary medicine. It is a first choice antiepileptic with high availability and economical. In dogs, an effectiveness between 60-93% has been described as a unique antiepileptic. According to systematic studies on its effectiveness, there is very good evidence in its use as monotherapy against idiopathic canine epilepsy.
Pharmacology and mechanism of action
It is absorbed in approximately two hours after administration and reaches the maximum plasma concentration between 4 and 8 hours. The elimination half-life is 40-90 hours after oral administration. Half of the drug is bound to proteins, it is mainly metabolized in liver and, about a third, is eliminated in the urine. It is an autoinducer of cytochrome p-450, which can accelerate its elimination and that of other hepatic metabolism drugs, so that its pharmacological effect is reduced. Its use is not recommended in patients presenting with hepatic dysfunction.
Its exact mechanism of action is still unknown, but among its actions are: prolongation of the opening of the chlorine channels in the GABA receptors, anti-glutamate effects and decrease of the calcium flow inside the neurons.
Most of the adverse effects appear at the beginning of the treatment or after an increase in the dose and usually improve or disappear after 1-2 weeks. These adverse effects include: polyuria / polydipsia, polyphagia, sedation, ataxia and behavioral changes such as hyperexcitability.
With a lower frequency, idiosyncratic reactions such as hepatotoxicity or cytopenias may also occur, which usually resolve after discontinuation of treatment. Other reactions that are much less described are: superficial necrolitis dermatitis, pancreatitis and dyskinesias.
At an analytical level the most frequent effects are the increase in alkaline phosphatase, ALT, GGT, increases in cholesterol and triglycerides and a decrease in albumin and T4.
Dose and monitoring
The initially recommended dose is 2.5-3 mg / kg / 12 h, although doses of 5-6 mg / kg / 12 h can be reached. Stable blood phenobarbital levels are reached approximately after 15 days of treatment and should be measured at 15, 45, 90 and 180 days after the start of treatment and, subsequently, every six months in case of correct control. The recommended levels are between 15-35 μg / ml and, for good crisis control, the optimal levels are between 25-30 μg / ml. The timing of the sampling is irrelevant, since there are no significant differences in the concentration of the phenobarbital during the day.
It is an antiepileptic drug approved in Europe in 2013 for the treatment of idiopathic canine epilepsy. Several published studies have shown similar efficacy (76%) to that of phenobarbital in the control of epileptiform seizures. According to studies on its effectiveness, there is a good level of evidence in its use as monotherapy, but insufficient evidence in its use as an adjunct treatment.
However, a study conducted in 2017 shows that the percentage of controlled patients is lower than in previous studies (54% vs. 76%). It is important to note that there are recent publications demonstrating the effectiveness of imepitoin as an adjunct treatment with phenobarbital.
Potassium bromide (KBr)
It is an inorganic salt and one of the most used drugs for the treatment of canine epilepsy. It has been shown to be effective for the treatment of criВsis, although to a lesser extent than phenoВbarbital (73.9%). However, its effectiveness increases (72-95%) when it is administered as a second antiepileptic next to the phenobarbital in the event that crises cannot be controlled. Recent studies have also shown an efficacy of 69% as a second antiepileptic in dogs that were refractory to treatment with imepitoin. Despite these publications, and according to systematic studies on their effectiveness, there is good evidence in their use as monotherapy against idiopathic canine epilepsy, but the evidence is reduced when used as a second antiepileptic.
It is an S-enantiomer of the ethyl analog of piracetam. It is an effective drug against epileptiform seizures that, typically, has been used as a complementary treatment to other antiepileptic drugs, studies have recently been published on its use as monotherapy in structural epilepsy. In one of these investigations its utility was demonstrated to reduce epileptic seizures by up to 64% when used as a complementary treatment. However, it should be noted that, according to most publications, its antiepileptic effect lasts between 4-8 months in many cases. According to the systematic studies conducted on its effectiveness, there is good evidence in its use as a complementary anti-epileptic.
It is a sulphonamide that is used as an anti-epileptic along with other drugs, according to some publications shows an efficiency of 58-80%. However, according to systematic studies on its effectiveness, there is insufficient evidence for its use as an attached drug or as monotherapy. As with levetiracetam, its antiepileptic effect is lost at 2-7 months.
In addition to the drugs described above, there are other medications that can be used for the treatment of epilepsy, such as topiramate, gabapentin and pregabalin. In these three cases, systematic studies on its effectiveness confirm that there is insufficient evidence to recommend its use as a complementary treatment against canine epilepsy.
Approximately 70-80% of the absorbed drug is eliminated without change through the urine. It has a half-life of elimination of 2-4 hours and acts through different mechanisms such as, for example, facilitation of GABA and modulation of sodium and calcium channels. The recommended dose is 2-10 mg / kg / 8-12 hours. Adverse effects that can be observed after administration include ataxia, irritability and sedation.
A study carried out in 2013 evaluated the efficacy of topiramate as complementary treatment to phenobarbital, potassium bromide and levetiracetam.
It is a drug analogous to GABA. Several publications have evaluated its effectiveness as a complementary antiepivlÃ © ptico treatment.
It has a hepatic metabolization of around 30% without induction of hepatic enzymes and does not have a high binding to plasma proteins. Its maximum concentration in plasma is reached two hours after ingestion and the elimination half-life
It is 3-4 hours. Its mechanism of action is based on the inhibition of calcium channels, decreasing the release of excitatory neurotransmitters. The most common adverse effects are sedation and ataxia. The recommended dose in dogs is 10-20 mg / kg / 8 hours and reaches stable levels after 24 hours of treatment.
This is another GABA analogue drug. There are few publications of its use as a complementary antiepileptic but its effectiveness reaches 70% of the patients evaluated.
It does not present hepatic metabolism or binding to plasma proteins and is excreted by the urinary tract without changes. The elimination half-life is 7 hours. It acts on calcium channels by decreasing calcium currents. The most commonly described adverse effects are ataxia, sedation and irritability. The recommended dose in dogs is 3-4 mg / kg / 8-12 hours.
Vagal nerve stimulation
It consists of the surgical placement of a device that releases repetitive electrical stimulations to the left cervical vagus nerve and whose use has been approved in people of all ages and with any type of epileptiform crisis.
The mechanism by which it produces antiepileptic effects is not fully studied, but it is believed that the estimation of vagal afferent fibers influences brain activity by modulating the syndromic synergistic and cholinergic synaptic transmission.
Preclinical studies have shown that stimulation of the left cervical vagal trunk by this device prevents experimentally induced epileptiform seizures. However, a published study showed that there were no significant differences in the frequency, severity, or duration of epileptiform seizures between a group of ten dogs with idiopathic epilepsy refractory to treatment and a control group, although a decrease in the frequency of Crisis in 34% of dogs treated with this device in the last four weeks of treatment.
The ketogenic diet is the best known dietary treatment for human epilepsy. It consists of a diet high in fat, low in protein and low in carbohydrates, with the aim of mimicking the biochemical changes that occur in fasting to enhance the energy metabolism dependent on mitochondria in neurons, the inhibition of Metabolic glutaminic pathways and synaptic transmission.
Studies in dogs with this type of diet showed no efficacy against a control group. However, studies with diets based on medium-chain triglycerides showed efficacy in terms of decreasing the frequency of epileptiform seizures in 71% of dogs as an attached veterinary treatment when compared to a group of animals with a plaВcebo diet. . This is mainly due to the anticonvulsant properties of medium chain tri-glycides.
Studies have also been carried out on the use of supplementation with omega 3 fatty acids in dogs with idiopathic epilepsy in which no benefit has been demonstrated compared to control groups.