Lect 16

• No great mind has ever existed without a touch of madness, according to Aristotle.
• Psychoactive veterinary drugs that are FDA-approved, their approved uses, and most veterinary psychoactives used are extra-label are topics discussed in DVM 611 P Harcmacology.
• Psychoactive medications are used in vet med to reduce underlying emotional arousal (fear, anxiety, stress) that contributes to undesirable behaviors.
• Serotonin is a neurotransmitter that is used in the mechanism of action of many psychoactive medications.
• Long-term (daily) psychotropics are used for conditions that need continuous treatment, while short-term (event) psychotropics are used for conditions that need treatment for a specific event.
• Common classes of long-term (daily) psychotropics include benzodiazepines, GABA, and anti-emetics and emetics.
• Individual drugs discussed in each class include clinical uses/indications, efficacy onset, mechanisms of action, pharmacologic properties, dosing, and side effects or contraindications.
• The route of administration that is efficacious and recommended for a specific drug is important to understand.
• Behavior-modifying drugs are referred to as psychotropics, psychopharmaceuticals, psychopharmacology, and behavioral meds.
• Mostly dogs and cats are treated with behavior-modifying drugs, but some horses, birds, and other species are also treated.
• Behavior-modifying drugs are used to treat conditions such as fear, anxiety, stress, and behavioral disorders.
• The use of behavior-modifying drugs in veterinary medicine is increasing due to their ability to improve the quality of life for both pets and owners.
• Mental health is important for overall well-being.
• Neurotransmitters targeted by psychotropic medications include Transmitter amines (Serotonin, Dopamine, Norepinephrine), Transmitter amino acids (GABA, Glutamate), and Transmitter monoamines (Dopamine).
• Indications for long-term (daily) psychotropics include generalized anxiety, fearful behavior leading to aggression, inter-pet conflict, separation anxiety, cognitive dysfunction syndrome, urine marking (vertical) in cats, stress-related house soiling, and repetitive behaviors (compulsive disorders, e.g., spinning, licking, fly-biting, etc).
• Common classes of long-term psychoactives include Selective serotonin reuptake inhibitors (SSRIs), Tricyclic antidepressants (TCAs), Azapirones (Serotonergic), and Monoamine oxidase inhibitors (MAOIs).
• When to use psychotropics include Veterinary-Client-Patient-Relationship (VCPR), underlying medical condition, behavior history, behavioral diagnosis, knowledge of which medications affect which neurotransmitters, and adjunct/combo with behavioral modification.
• There are two major categories of psychotropics: Long-term or "Daily" for chronic use, and Short-term or "Event" medication for acute use.
• Psychotropics can be used in Veterinary Medicine for a variety of reasons, including managing behavioral health conditions, treating underlying medical conditions, and aiding in surgical procedures.
• Behavioral health conditions that can be managed with psychotropics include Mental health conditions such as anxiety, fear, aggression, and phobias, and Physical health conditions such as diabetes, Cognitive Dysfunction Syndrome, and urine marking (vertical) in cats.
• Use of SSRIs can cause serotonin syndrome in animals with diabetes, dogs with epilepsy or history of seizure disorders, and animals with severe hepatic impairment.
• Sertraline is used in human patients with hepatic disease and may be safest if the animal has epilepsy.
• Herron 2021SSRIs: Contraindications, adverse/side effects include decreased appetite or GI upset, mild sedation, lethargy, decreased grooming in cats, anxiety, restlessness, urine retention, seizures, aggression, and competitive inhibitor of cytochrome P450 liver enzyme.
• Fluoxetine, the most commonly used SSRI, is also the most studied and has indications/uses including canine separation anxiety, repetitive behaviors, stereotypies, compulsive behaviors, generalized anxiety, urine marking/spraying in cats, and house soiling.
• Sertraline, another SSRI, also has no dog/cat placebo-controlled clinical trials, is primarily fecal excreted, skips kidney, and is safer for CKD animals.
• Herron 2021Serotonin syndrome is a condition that can occur from excessive intake of medications increasing serotonin levels or impacting serotonin metabolism.
• Fluoxetine is a highly selective inhibitor of serotonin reuptake and is well absorbed after oral administration with very poor bioavailability with transdermal (~10% of oral) – do not recommend.
• Paroxetine, another SSRI, has no dog/cat placebo-controlled clinical trials, may be appetite enhancing, has mild anticholinergic effects (constipation), and has a shorter half-life necessitating sometimes twice-daily dosing.
• Serotonin syndrome is not recommended (contraindicated) to combine SSRIs with TCAs or MAOIs (including Amitraz), and caution is warranted with serotonin precursors (tryptophan), St. John’s Wort, and others.
• Behavior-Modifying Drugs include Tracycline Antidepressants (TCAs), which inhibit both serotonin and norepinephrine, increasing the availability of neurotransmitters in synapses.
• Venlafaxine is not commonly used and is not discussed in this section of long-term psychotropic medications.
• Selective serotonin reuptake inhibitors (SSRIs) are classified as antidepressants with other properties including anxiolytic, anti-compulsive, and some anti-aggression properties.
• Selective serotonin reuptake inhibitors (SSRIs) should not be used “as needed” as they are ineffective.
• The uses and indications of Selective serotonin reuptake inhibitors (SSRIs) include generalized anxiety disorders, obsessive compulsive or repetitive/stereotypic behaviors, urine marking, and some aggressive behaviors.
• The initial actions of Selective serotonin reuptake inhibitors (SSRIs) involve blocking reuptake, which can cause serotonin to flood all receptors, leading to side effects.
• Selective serotonin reuptake inhibitors (SSRIs) are metabolized in the liver and excreted through the kidneys, and there is no relationship between plasma levels of SSRIs and response.
• All of the drugs discussed in this section of long-term psychotropic medications are orally administered.
• Selective serotonin/norepinephrine reuptake inhibitors (SNRIs) include Venlafaxine, which is not commonly used and not discussed in this section.
• The therapeutic effect of Selective serotonin reuptake inhibitors (SSRIs) is due to the postsynaptic auto receptor becoming more active with time, while the presynaptic serotonin autoreceptor, which is responsible for side effects, downregulates over 4-6 weeks, leading to side effects waning.
• Selective serotonin reuptake inhibitors (SSRIs) are used in conjunction with behavior modification and can be used with acute/event drugs.