Psychotropic drugs and natural products can be used to reestablish a more stable emotional state and improve trainability in animals that are anxious, fearful, or overly reactive. Drugs might also be effective in the treatment of behavior that is abnormal, pathologic, or lacking impulse control. In addition, drugs may be indicated to improve compromised welfare. However, whereas drugs can improve the animal's emotional state and facilitate new learning, only with concurrent behavior modification can new neuronal pathways be established, new behaviors learned, and fearful responses to stimuli changed to positive ones.
Evidence-based decision making is a way to provide the best information and treatment options. Treatment should be selected using the evidence combined with the clinician’s expertise regarding the animal, client, and problem. Very few drugs have been adequately tested in rigorous, randomized, controlled trials for use in veterinary behavioral therapy. In fact, most drugs used in veterinary behavioral therapy are human drugs, very few of which have had pharmacokinetics established for animal species. This can lead to inaccurate assumptions with respect to dosage, duration of effect, contraindications, and adverse effects. In addition, there is a wide range of published dosages based on the application, individual variability, and desired outcome. Therefore, practitioners should remain current with the most recent veterinary behavior literature with respect to indications, recommended dosages, evidence of efficacy, potential adverse effects, and contraindications before dispensing any of these medications. (For dosing guidelines, see Table: Drug Dosages for Behavioral Therapy in Dogs and Cats Drug Dosages for Behavioral Therapy in Dogs and Cats 
). Depending on the drug and patient, compounding may be required to achieve an appropriate dosage and formulation for administration; however, reformulation may alter a drug’s pharmacokinetics, safety, efficacy, and stability. Recent studies on the use of transdermal preparations of behavioral drugs such as fluoxetine, amitripyline, and buspirone have found little to no absorption of transdermal preparations versus oral dosing.
A variety of natural products have been used to treat anxiety; however, only a few have demonstrated any evidence to support efficacy. Products that have published studies indicating potential therapeutic effects to calm and reduce underlying fear and anxiety include the canine appeasing pheromone (Adaptil®), the feline cheek gland pheromones (Feliway® and Felifriend®), a feline pheromone that might aid in scratching post training (Feliscratch®), l-theanine (Anxitane®), α-casozepine (Zylkene®), a diet supplemented with α-casozepine and l-tryptophan (Royal Canin Calm™ Feline and Canine), a product combining Magnolia officinalis and Phellodendron amurense (Harmonease®), a Souroubea sp supplement (Sin Susto™), as well as perhaps melatonin, and lavender aromatherapy.
A physical examination and blood and urine tests should be part of a minimum database before dispensing drugs to ensure there are no underlying medical problems that may be causing or contributing to the behavioral signs, or that might have an impact on drug selection and use. For tricyclic antidepressants and selective serotonin reuptake inhibitors, 4 wk may be required to achieve optimal therapeutic effect.
