Dr. Thomas' article - Rectal Diazepam for Cluster Seizures in Dogs

HOME TREATMENT WITH RECTAL DIAZEPAM

FOR CLUSTER SEIZURES IN DOGS

By W.B. Thomas DVM, MS, Dipl. ACVIM (Neurology)

The purpose of this article is to provide general information about home treatment with rectal diazepam (valium) for dogs with cluster seizures. It discusses the treatment recommended by the Neurology/Neurosurgery service at the Veterinary Teaching Hospital, College of Veterinary Medicine, University of Tennessee. Because clinical circumstances vary widely and each patient is unique, specific recommendations can only be made by the attending veterinarian.

Why is home treatment necessary for some dogs?
Most dogs with idiopathic epilepsy suffer isolated seizures that stop spontaneously within one to three minutes. However, some dogs with epilepsy tend to suffer cluster seizures or status epilepticus. Status epilepticus is defined as (1) a continuous seizure lasting at least 5 minutes or (2) two or more discrete seizures without full recovery of consciousness between seizures. Cluster seizures (serial seizures, acute repetitive seizures) are two or more seizures occurring over a brief period (minutes to hours) but with the patient regaining consciousness between the seizures.1

While a single seizure of short duration is rarely life-threatening, status epilepticus is a medical emergency requiring prompt treatment. Continuous seizure activity lasting 30 to 60 minutes can lead to profound, life-threatening abnormalities and brain damage. 2 Although cluster seizures do not fulfill the definition of continuous seizure activity, they nevertheless represent a serious condition that can progress to status epilepticus. The goal of treatment is to quickly stop the seizure and provide support for the patient. Typically, this involves urgent veterinary care, including administering anti-seizure medication by vein. The financial and emotional distress of repeated emergency treatment is a common reason for a client to have an epileptic pet euthanized.

Why is rectal administration of diazepam recommended?
Rectal administration of diazepam (valium) by the client is a safe method of home treatment of cluster seizures in dogs with idiopathic epilepsy.3 Diazepam belongs to the class of drugs known as benzodiazepines. Benzodiazepines are the treatment of choice for the emergency treatment of seizures because they are safe, work quickly, and are effective against many types of seizures. Veterinarians typically administer diazepam by vein to quickly stop a seizure, but most clients are not adept at intravenous injections. Absorption of diazepam after injection into the muscle is variable and unpredictable and may cause muscle damage.4 Giving diazepam by mouth is difficult and hazardous when the dog is actively seizing, and absorption after oral administration is slow and unpredictable.4 On the other hand, rectal administration of diazepam results in higher and earlier blood levels compared with either oral or intramuscular routes, making this route of administration ideal for home treatment of cluster seizures.4

Which dogs are candidates for home treatment with rectal diazepam?
This treatment is considered in dogs with a tendency to suffer multiple seizures during a 24-hour period. A primary goal of treatment in these dogs is to prevent the seizures with daily anti-seizure medication. If this is not totally successful and the patient still tends to suffer cluster seizures, then home treatment with rectal diazepam should be considered. This treatment is not recommended for the majority of dogs with idiopathic epilepsy that tend to suffer single, isolated seizures.

How is the treatment administered?
This treatment uses commercially available diazepam injectable solution. Although this solution is intended for injection by vein, studies have shown that this product is absorbed well when given rectally. The syringe is filled with the appropriate dose of diazepam and then attached to a 1-inch teat cannula or similar device. This is inserted approximately one inch (2 cm) into the dog's rectum and the syringe's plunger is pushed, delivering the diazepam. The first treatment is given as soon as possible after the onset of a seizure. The same dose can be repeated for a total of 3 times within a 24-hour period. If the seizures do not stop or if the dog appears to be having difficulty breathing, the pet should be taken to a veterinarian for emergency treatment.

What dose of diazepam is used?
Each patient is different, so specific recommendations can only be made by the attending veterinarian. A dose of 2 mg per kg of body weight is usually recommended for dogs taking Phenobarbital (Phenobarbital is known to increase the dose requirement for diazepam).5 In dogs not taking Phenobarbital, the dose is usually 0.5 to 1 mg per kg.

Isn't this a high dose of diazepam?
The rectal dose is higher than the intravenous dose in order to obtain adequate blood levels. Also, as mentioned above, long-term treatment of Phenobarbital increases the dose requirement as well. These doses have been found to be quite safe in experimental studies in dogs.5

What about diazepam suppositories?
Some pharmacists can compound diazepam suppositories. Also, a gel formulation of diazepam (Diastat) has recently become available for rectal administration in human patients.6 However, these are not currently recommended because the absorption of these products has not been studied in dogs.

Is it legal for me to have diazepam?
In the United States, diazepam is a prescription drug. Clients need to obtain the diazepam from their veterinarian or have a prescription from their veterinarian in order to obtain diazepam from a pharmacy. Diazepam is also a controlled substance, as is Phenobarbital. This means there are certain additional requirements the veterinarian must follow when writing a prescription for or dispensing the drug. The purpose of controlled substance regulations is to minimize inappropriate use of these drugs, not prevent their beneficial use in patients that need such therapy. Because injectable diazepam solution is used mostly in hospitals, many pharmacies do not carry this product. However, it can usually be obtained from hospital pharmacies or ordered by a pharmacist or veterinarian.

Address questions or comments to:
W.B. Thomas DVM, MS, Dipl. ACVIM (Neurology)
Wthomas@utk.edu

References:

1. Lowenstein DH, Alldredge BK. Status epilepticus. New Engl.J.Med. 1998; 338:970-976.

2. Lothman EL. The biochemical basis and pathophysiology of status epilepticus. Neurology 1990; 40(suppl 2):13-23.

3. Podell M. The use of diazepam per rectum at home for the acute management of cluster seizures in dogs. J.Vet.Int.Med. 1995; 9:68-74.

4. Papich MG, Alcorn J. Absorption of diazepam after its rectal administration in dogs. Am.J.Vet.Res 1995; 56:1629-1636.

5. Wagner SO, Sams RA, Podell M. Chronic phenobarbital therapy reduces plasma benzodiazepine concentrations after intravenous and rectal administration of diazepam in the dog. J.Vet.Pharmacol.Therap. 1998; 21:335-341.

6. Dreifuss FE, Rosman NP, Cloyd JC, Pellock JM, Kuzniecky RI, Lo WD, et al. A comparison of rectal diazepam gel and placebo for acute repetitive seizures. New Engl.J.Med. 1998; 338:1869-1875.