Medication for the Anxious, Fearful Dog and Cat
Jill Sackman, DVM, PhD, DACVS
Transporting and handling a fearful and anxious dog or cat in a veterinary practice can be challenging. It has been reported that nearly 80% of dogs that visit veterinary practices for examination exhibit signs of anxiety or fear (Doring, et al 2009). Fearful dogs and cats resist restraint and may display signs of aggression when handled. Although fear-based aggression in dogs and cats is not uncommon, one negative visit has the impact of making every subsequent visit even worse!
Acepromazine is a dissociative agent; it inhibits logical environmental assessment. Often referred to as “ace,” acepromazine is routinely used to sedate fearful or aggressive dogs. Research has shown that acepromazine functions primarily as a chemical restraint without affecting the animal’s emotional behavior. However, while under the influence of “ace,” animals still have strong anxiety, avoidance or arousal responses, but they either don’t display these reactions, or they are delayed in reacting. The dog may appear calm but is still having an intense emotional reaction. Fear may intensify to a level in which it overrides the physiological sedative effects of “ace”; the animal seems ‘out of it,’ but the intense emotional reaction causes him to bite. This increased fear will certainly be remembered.
What should we do?
What else can we do to reduce the stress and upset that these visits often trigger? Pharmacologic agents that have anxiolytic and sedative properties administered in a noninvasive way are ideal.
Anxiolytic drugs – Benzodiazepines
Benzodiazepines such as alprazolam (Xanax®), clonazepam, (Klonopin®), clorazepate (Tranxene®) and lorazepam are alternative drugs which affect the central nervous system and reduce anxiety, stress and fear. They have a calming and amnesic effect on the patient. These drugs have fast-acting effects that begin within 30 minutes to 2 hours after oral administration. They have the benefits of rapid onset of action and potent anxiolytic action and can be especially useful for episodic anxieties.
Alprazolam is used to treat anxiety in dogs and cats. Uses include treatment of thunderstorm and other phobias, separation anxiety and situational fears (such as car travel and veterinary visits). Like other benzodiazepines, alprazolam may be used as a muscle relaxant, anticonvulsant or appetite stimulant. Although generally safe, the most common side effect is excessive sedation and loss of motor control. These effects occur at doses greater than those needed for its anxiety-reducing effect. In some, alprazolam may cause a paradoxical excitement or worsen aggression. Long-term treatment with alprazolam can lead to physical dependence, which can result in undesirable behavior changes if the drug is abruptly discontinued.
Benzodiazepines are best given one to two hours before the exam and repeated 30 minutes before the exam. Most benzodiazepines are scored and easily cut further with a pill cutter, but they melt if hands or surfaces are damp. For patients that do not take tablets well, benzodiazepines can be made into a paste with a tiny bit of water and smeared on the gums or tongue. As soon as the patient licks or swallows, the medication enters the system.
Trazodone is a serotonin antagonist and reuptake inhibitor (SARI) used for anxiety disorders in dogs and cats. Recently, (Orlando, J Feline Med Surg 2015) trazodone was used to sedate cats prior to stressful veterinary visits and exams and evaluated for safety and efficacy. The observed sedation resulted in no adverse effects with the use of trazodone at 50-100 mg. Likewise in dogs, trazodone has been effectively used to support post-surgical confinement in dogs (Gruen, et al JAVMA 2014) at 7 mg/kg PO q 12 hours.
Trazodone is available as tablets in 50 mg, 100 mg, 150 mg, and 300 mg. Based on owner reports, the onset of action in dogs is approximately 1 hour, so if using for travel anxiety, dosing in advance is recommended.
Trazodone was used in a recent study (Gruen, unpublished results) as a single agent at doses of 5-30 mg/kg/day (divided q8-12 hours). The mean dose for this population was 15 mg/kg/day. When used as an adjunctive medication, starting doses for trazodone are typically lower, and dose is titration used to achieve clinical success. Dogs may require incremental dose increases as they become tolerant to the effects of trazodone.
Trazodone has a large safety margin for the majority of our canine patients. As an antidepressant, trazodone is prescribed in humans at up to 600 mg/d. The LD50s for mice, rats, and rabbits are 610 mg/kg, 486 mg/kg, and 560 mg/kg respectively.
To reduce fear in anxious canine patients, α2-adrenergic agonists have been used parenterally. Although a commercially available oral transmucosal (OTM) formulation of detomidine is approved for sedation and restraint in horses, there are currently no reports on its use in dogs, and no α2-agonist has been approved for OTM administration in dogs.
A recent study (Hopfensperger, et al 2013) evaluated the behavioral and physiological effects of OTM detomidine gel (Dormosedan Gel; Pfizer Animal Health, Madison, NJ) in dogs. Based on pre- and post-treatment assessments, dogs were deemed to be more sedated, less anxious and easier to handle. The gel was safely administered, and the dose (0.35mg/m2) resulted in measurable signs of sedation and anxiolysis.
Medications for fear and anxiety in cats and dogs
Medication Cat Dog
|Alprazolam||0.0125-0.025 mg/kg by mouth every 8 hours||0.01-0.1 mg/kg by mouth every 4-5 hours|
|Clonazapam||0.1 to 0.5 mg/kg orally every 8 hours||0.1 to 0.5 mg/kg orally every 8 hours|
|Clorazepate||0.2 to 0.4 mg/kg every 12 to 24 hours||1 to 2 mg/kg orally every 8 to 12 hours|
|Lorazepam||0.05 mg/kg by mouth every 12-24 hours up to 0.125-0.25 mg/cat||0.02-0.1 mg/ kg by mouth every 8-12 hours.|
|Maropitant citrate (Cerenia®) – for travel nausea||NA||2-8 mg/kg by mouth every 24 hours|
|Midazolam||0.05-0.3 mg/kg SQ, IM or IV only. Consider more for sedation except at lower doses that are anxiolytic.||0.05-0.3 mg/kg SQ, IM or IV only. Consider more for sedation except at lower doses that are anxiolytic.|
|Trazodone||0.5 mg/kg (approximately 2.5-3 mg per cat) by mouth every 8 hours||2-3 mg/kg by mouth every 12-24 hours|