Diazepam For Veterinary Use

by Barbara Forney, VMD

Basic Information

Diazepam is a benzodiazepine tranquilizer. Drugs in this class act directly on the brain and are central nervous system (CNS) depressants. Although the precise mechanism of action is not fully known, specific benzodiazepine receptors have been found in the brain and other tissues including the heart, kidney, liver and lungs. Diazepam is used clinically for sedation, to diminish anxiety or modify behavior, as a muscle relaxant, an anticonvulsant and in some species as an appetite-stimulant. It may be administered intra-venously, intra-muscularly, orally and rectally via suppository or enema. Diazepam is metabolized by the liver to nordiazepam and other active metabolites. They are excreted in the urine.

Dogs and Cats

Diazepam can be used as a sedative either alone or in combination with other drugs. It is considered a relatively safe pre-operative sedative for patients with underlying cardiac or metabolic diseases because it causes minimal cardiopulmonary-side-effects and provides good muscle relaxation. It may be used in combination with ketamine for induction of anesthesia.

Diazepam is used in both dogs and cats as an anti-anxiety drug and to treat many behavioral problems including some stereotypic behaviors. These behaviors include separation anxiety, fear of loud noises or thunderstorms, territorial or social aggression between animals, urine marking or spraying and hair loss due to excessive licking or grooming. Diazepam can be used to treat aggressive dogs to make them more manageable, although occasional individuals can have a contradictory reaction and become more aggressive. If diazepam is used in a potentially aggressive animal, it is important to be aware of this possibility, warn the animal's handler and take appropriate precautions. Because diazepam causes drowsiness and decreased coordination, it may impair the ability of working dogs. Diazepam alone is less likely to be effective as a sedative when used in an animal that is already excited.

Diazepam frequently is used to treat seizures. It is the treatment-of-choice for clusters of seizures or status epilepticus in both dogs and cats. It is used in the emergency treatment of seizures due to poisoning or intoxication. It also is used for the long-term management of seizures in cats (either alone or in combination with other drugs). Diazepam is not as commonly used in the long-term management of epilepsy in the dog because it loses effectiveness within a few weeks. Other drugs such as phenobarbital or potassium bromide are used more commonly for this purpose in dogs.

Diazepam is used as a muscle relaxant either alone or in combination with other drugs. It can be used to treat pain and muscle spasm associated with many conditions including inter-vertebral disc disease, urethral obstruction, muscle cramping, tremors and tetanus.
It is used in combination with corticosteroids to treat "Little White Shakers Syndrome” in Maltese and West Highland white terriers.

Diazepam is a powerful appetite-stimulant in the cat.

Horses

Diazepam is used most frequently in horses as a part of a pre-operative sedative combination and to treat seizures both in the neonate and in adult horses. It is not used commonly on its own as a sedative in adult horses but can be used to sedate neonates. It generally is considered a safe choice in the young foal because it causes minimal cardiovascular depression, while providing good muscle relaxation and CNS depression. It is important to note that diazepam provides little or no analgesia.

When diazepam is used pre-operatively, it is given in combination with other drugs such as xylazine, ketamine, glycerol guaiacolate and butorphanol. Many practitioners report that the inclusion of diazepam in the traditional xylazine/ketamine anesthesia provides for longer "down-time" and a smoother recovery.

Diazepam is used to control seizures and status epilepticus in both adult horses and foals. It may be used alone or in combination with other drugs including xylazine, detomidine, glycerol guaiacolate, methocarbamol, pentobarbital, phenobarbital and others. The drug choices, combinations and doses will vary with the underlying cause of the seizures.

Diazepam also is used to diminish sexual inhibition in order to improve breeding behavior in the slow or shy stallion.

Diazepam Side Effects

• Common: weakness, drowsiness and loss of coordination.
• Rare: paradoxical excitement, aggression or unusual behavior. Liver failure is a rare but serious side effect that can occur in cats after receiving oral diazepam for several days. Affected cats do not have a prior history of liver disease or elevated enzymes. The cause of this hepatic toxicity is not known at this time.

Precautions

• Diazepam should be used with caution in debilitated or geriatric animals, animals with decreased kidney or liver function, animals in shock, coma or with significant respiratory depression.
• Diazepam may be addictive and should not be withdrawn abruptly from those animals that have been on long-term treatment.
• Some animals may show unexpected behavior such as excitement or aggression after administration of diazepam. Alternative drugs should be considered in these animals.
• Intravenous injection of diazepam should be performed slowly, particularly when used in small animals or when injecting into smaller veins because of potential thrombophlebitis and cardiotoxicity due to the propylene glycol base.
• Diazepam should not be stored in plastic syringes or bottles as it may adsorb to the plastic and become inactivated.
• Diazepam should be avoided in pregnant or lactating animal and be used only when the benefits clearly outweigh the risks. In humans, it has been shown to be teratogenic when used during the first trimester of pregnancy. Diazepam crosses the placenta and is present in milk.

Drug Interactions

• Diazepam is a CNS depressant. When given with other CNS-depressant drugs (tranquilizers, narcotics, barbiturates, MAOIs, antihistamines and antidepressants) the effects will be additive.
• Cimetidine, erythromycin, isoniazid, ketoconazole, propanolol and valproic acid slow the metabolism of diazepam. The dose of diazepam may need to be decreased.
• The effects of digoxin may be increased in patients receiving diazepam. Serum digoxin levels may need to be checked and patients monitored for signs of toxicity.
• Antacids may delay the absorption of oral diazepam. This can be managed by separating the medications by two hours.
• Rifampin may decrease the effect of diazepam.

Overdose

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