The use of drugs to influence behaviour, including altering mood and emotional responses, is known as psychopharmacology. In veterinary medicine, behaviourally-active medication is most commonly used in dogs, and to a lesser extent in cats. Behaviourally-active drugs will generally either have a calming effect, for example through reducing anxiety and/or causing mild sedation, or they can have a longer-term effect on reducing negative emotional responses, such as anxiety, fearfulness or frustration, which can reduce stress and improve wellbeing generally.
Behaviourally-active drugs can improve welfare in animals in both the short and longer term, and can also play an important role in the successful treatment of some problem behaviours. Used judiciously, their calming effects can make fearful animals easier, and safer, to handle in the veterinary surgery as well as in other environments, and they can also reduce the risk of animals becoming even more fearful in these environments in future.
Although the Veterinary Surgeons Act 1966 legally prevents veterinary nurses from prescribing medication, in the course of their work, they are very likely to encounter animals that would benefit from behaviourally-active medication either to facilitate handling in the veterinary surgery or to address problem behaviours or situations that are detrimental to an animal's welfare in other contexts. Therefore, veterinary nurses in general practice should ideally have an understanding of psychopharmacology, including an awareness of what drugs are available and how they work. They may also be asked about behavioural medication by owners, for example to help dogs fearful of noises in the run-up to the firework period. Owners of animals already on behaviourally active medication may also seek help and support from veterinary nurses, for example if they have concerns about potential side effects or lack of any obvious behavioural improvement.
It is hoped that this three-part article will give veterinary nurses a comprehensive introduction to the principles of using psychoactive medication in companion animals. Part 1 comprises an overview of the main types of behaviourally active drugs that are available for treating dogs and cats in the UK, and the different types of behavioural problems that they can potentially help. Part two will give a more detailed look at the decision-making process for using short-acting behaviourally-active medications, including to help animals that are fearful and potentially difficult to handle in the veterinary surgery. Part 3 will outline ways in which veterinary nurses can contribute to improving the behavioural welfare of their patients generally, including how to identify those animals that may benefit from psychoactive medication, who to refer these cases to, what to expect when animals are treated with these medications and how nurses can support the owners of animals that are undergoing treatment.
Types of drugs available and the sorts of behaviour problems they can help
While behaviourally-active drugs comprise several different classes of medication, they can be divided into two main types: short-acting drugs that can be given as needed (Box 1), and drugs that need to be given on a daily basis longer term (Box 2).
Box 1.Short-acting or situational medicationBehavioural effects of short-acting drugs:
- Generally have a calming effect, via reducing anxiety, causing sedation or both. Most drugs have the potential to both reduce anxiety and cause sedation depending on the dose given, but at normal doses some drugs tend to be more anxiolytic, such as benzodiazepines, while others tend to be more sedative, such as gabapentin
- Onset of effect fairly rapid, and effect also wears off quite quickly (within a few hours)
Uses:
- To prevent pre-existing fear or anxiety-related problems getting worse when exposure to problem triggers is unavoidable. For example:
- Dogs that are fearful of bangs over the firework period and New Year's Eve
- Cats that are scared of car travel that need to travel to come into the surgery or to go to a cattery
- Dogs that are difficult to handle in the veterinary surgery that need an appointment because they are unwell or because they are due for a vaccination
- Dogs that are fearful and/or difficult to handle when they go to the groomers.
- Work best if given before an animal becomes scared, so they are ideal for planned or otherwise predictable events, e.g. before a veterinary examination or grooming appointment, before a neighbourhood firework display
- If given after an animal has already become fearful, such as when a dog has been scared by unexpected fireworks they can still have some beneficial effect, but will be harder to dose the animal and the drug will generally not be as effective as when given while the animal is calm
- Can also be used alongside longer-term behavioural medication:
- To provide behavioural support during the first few weeks of treatment until longer-acting drugs reach their full therapeutic activity
- To help animals on longer-term behavioural medication cope better with particularly difficult situations, such as over the firework period for dogs that are generally noise-sensitive, or before a veterinary examination for dogs that are fearful of strangers
The short-acting medications most commonly used in dogs and cats in the UK are outlined in Table 1
Table 1. Short-acting behaviourally active drugs most commonly used in dogs and cats in the UK
| Class | Drug | Main mode of action | Behavioural conditions most suitable for | Approx time to onset of effect | Approx length of activity | Most common side effects | Dose ranges and dosing information |
|---|---|---|---|---|---|---|---|
| Benzodiazepines | Alprazolam | Binds to GABAA receptors. Reduce anxiety and panic. Can be sedative at higher doses | Short-term reduction of anxiety, fears and phobias in dogs, e.g. firework fears, car travel. Used less frequently in cats as other drugs e.g. gabapentin appear more effective | 30–45 mins | 4 hours |
|
Dog: 0.01–0.1 mg/kgCat: 0.125–0.25 mg/cat (trial and error may be needed to find most effective dose). For very fearful or anxious animals can give a dose the evening before a predicted scary event and a second dose about an hour before the event |
| Diazepam | Binds to GABAA receptors. Reduce anxiety and panic. Can be sedative at higher doses | Short-term reduction of fears and phobias in dogs, e.g. firework fears, car travel | 45–60 mins | Up to 6 hours |
|
Dog: 0.5–2 mg/kg (trial and error may be needed to find most effective dose)Cat: 0.2–0.4 mg/kg per os (PO) every 8 hours or 1.25–5.0 mg/cat | |
| Other anticonvulsant drugs with sedative/anxiolytic effects | Gabapentin | Inhibits release of various excitatory transmitters including glutamate, noradrenaline and substance P. Does not bind to GABAA receptors but increases GABA activity indirectly | Short-term sedation and reduction of fear and anxiety in dogs and cats. Can be effective when used alone in cats to reduce fear of veterinary visits and car travel etc. May need to be supplemented by other medications in dogs | 1–2 hours | 8 hours + |
|
Dog: 10–20 mg/kg as single doseCat: 50–100 mg/cat as single doseFor very fearful animals can give a dose the evening before a predicted scary event and a second dose 1–2 hours before the event Absorbed best on empty stomach |
| Imepitoin | Low affinity partial agonist of the benzodiazepine binding site on the GABAA receptor, plus weak calcium-channel blocking activity | Licensed in UK as Pexion (Boehringer Ingelheim) for the reduction of anxiety and fear associated with noise phobia in dogs | 2–3 hours | 12 hours |
|
Dogs: For short-term dosing give 30 mg/kg every 12 hours starting 2 days before expected event and continue through the event. Absorbed best on empty stomach | |
| Alpha 2 adrenergic agonists | Dexmedetomidine oro-mucosal gel | Selective alpha-2 adrenoceptor agonist, reduces activation of locus coeruleus in response to stressors/threats. Low dose via oromucosal route should reduce anxiety without causing sedation or cardiovascular effects | Licensed in UK as Sileo (Zoetis) for short-term treatment of noise aversion in dogs. Potential to be useful in other situations, e.g. veterinary visits, car travel, grooming | 30–60 mins | 2–3 hours. Can repeat up to 5 times if needed |
|
|
| Clonidine | Non-selective centrally acting a2-adrenergic agonist | Reduction of high arousal and panic: generally used as add-on agent in dogs on longer-term medications such as TCAs or SSRIs | 1–2 hours | Around 8 hours |
|
Dog: 0.01-0.05 mg/kg, can be used as needed (given 1–2 hours before exposure to anticipated stressful situation) or every 8–12 hours | |
| Serotonin antagonist and reuptake inhibitors (SARIs) | Trazodone | Increases serotonin activity. Also blocks histaminic and a1-adrenergic receptors | Short-term anxiolytic and sedative effects, e.g. before veterinary visits, groomers, travel etc (dog and cat) N.B. studies suggest gabapentin may be more effective than trazodone for cats before travel, veterinary visits etc | 1 hour | 8 hours + |
|
Dog:
|
(Overall, 2013; dePorter et al, 2016; Ramsey, 2017; Plumb, 2018)
Box 2.Longer-term behaviourally-active medicationBehavioural effects of longer-term drugs:
- Most influence serotonin, and to a lesser extent noradrenaline and dopamine, pathways in the brain
- Can reduce negative emotional states such as fearfulness, anxiety and frustration
- Varying effects on arousal levels: some drugs tend to have a calming effect while others may increase arousal
- Improve an animal's ability to learn more appropriate behaviours, indirectly through reducing stress and more directly through encouraging physiological processes important for learning such as long-term potentiation
- Tend to have a slow onset of effect: often take several weeks to start to become effective and sometimes several months to become fully effective
Uses:
- Longer-term treatment of behavioural disorders associated with fear, anxiety or sometimes frustration, where exposure to problem triggers is constant, frequent or highly unpredictable, for example:
- Generalised anxiety
- Fears of things that are encountered frequently and/or unpredictably, e.g. unfamiliar people, other dogs, noises
- To reduce chronic stress associated with ongoing social tension in cats (may present as hiding away, inappropriate toileting, overgrooming)
- Abnormal repetitive behaviours in both cats and dogs
The drugs most commonly used to treat longer-term behavioural disorders in dogs and cats in the UK are outlined in Table 2.
Table 2. Behaviourally active drugs used for longer term treatment in dogs and cats in the UK
| Class | Drug | Main mode of action | Behavioural conditions most suitable for | Most common side effects | Dose ranges |
|---|---|---|---|---|---|
| Tricyclic antidepressants (TCAs) | Clomipramine | Increases activity of serotonin and noradrenaline. Also blocks histaminic, cholinergic and α1-adrenergic receptors | Licensed in UK as Clomicalm (Novartis) for treatment of separation anxiety in dogs. Has also been used successfully to treat a range of other fear and anxiety-related problems including noise fears and generalised anxiety, and also compulsive behaviours |
|
Dogs: 1–2 mg/kg per os (PO) every 12 hoursCats: 0.25–1 mg/kg PO every 24 hours |
| Specific serotonin reuptake inhibitors (SSRIs) | Fluoxetine | Increases serotonin | Licensed in UK as Reconcile (Forte Healthcare) for the treatment of separation anxiety in dogs. Has also been used successfully to treat a wide range of fear and anxiety-related problems including noise fears, separation anxiety and generalised anxiety, also compulsive behaviours and can reduce impulsivity |
|
Dog: 1–2 mg/kg every 24 hoursCat: 0.5–1 mg/kg every 24 hours |
| Sertraline | Increases serotonin. Very weak effects on noradrenaline and dopamine | Similar to fluoxetine, may be slightly more effective at reducing panic |
|
Dog: 1–3 mg/kg every 24 hours | |
| Azapirones | Buspirone | Increases serotonin | Has been used successfully to treat a range of fear and anxiety disorders, particularly in cats. These include urine marking, stress-related inappropriate urination, social tension, timidity. May increase pro-social behaviour towards people and other cats |
|
Dog: 1–2 mg/kg every 8–12 hoursCat: 0.5–1 mg/kg every 8–12 hours |
| Serotonin antagonist and reuptake inhibitors (SARIs) | Trazodone | Increases serotonin activity. Also blocks histaminic and α1-adrenergic receptors | While mainly used for short-term anxiolytic and sedative effects, trazodone can also be used to treat chronic anxiety problems in dogs that have not responded to other medications. Generally used as an adjunct to other longer-term medication |
|
Dog: 2–12 mg/kg every 12 hoursAdvise start on lower dose and increase gradually if necessary, particularly if dog is also on other serotonin-increasing medication |
| Monoamine oxidase inhibitors (MAOIs) | Selegiline | Small increases in monoamine neurotransmitters including serotonin and noradrenaline. Mainly increases dopamine. Metabolites include amphetamine and methamphetamine, both of which are stimulants | Licensed in UK as Selgian (CEVA) for ‘treatment of behavioural disorders of purely emotional origin in dogs, such as depression and anxiety, and, in association with behaviour therapy, for the treatment of signs of emotional origin observed in behavioural conditions such as overactivity, separation problems, generalised phobia and unsocial behaviour’. Not licensed in cats. Generally indicated for animals with fear-related problems associated with hiding and withdrawal rather than those showing high levels of arousal and reactivity. Can also be helpful in animals with cognitive dysfunction and in animals experiencing severe grief-related responses |
|
Dog: 0.5–1 mg/kg PO every 24 hoursCat: 1 mg/kg PO every 24 hoursBest dosed in morning due to stimulant effect |
| Anticonvulsant drugs with anxiolytic effects | Imepitoin | Low affinity partial agonist of the benzodiazepine binding site on the GABAA receptor, plus weak calcium-channel blocking activity | Licensed in UK as Pexion (Boehringer Ingelheim) for the reduction of anxiety and fear associated with noise phobia in dogs. May be used in combination with a behaviour modification plan for the control of anxiety in dogs in relation to both social stimuli (e.g. crowds, strangers) and non-social stimuli (e.g. noises, novel items, new environments) |
|
Dogs: 10–30 mg/kg twice dailyAbsorbed best on an empty stomach |
| Gabapentin | Inhibits release of various excitatory transmitters including glutamate, noradrenaline and substance P. Does not bind to GABA receptors but increases GABA activity indirectly | Generally used as an adjunct to other longer-term medication such as TCAs or SSRIs. Can be particularly useful in cases where behaviour is being exacerbated by chronic or neuropathic pain |
|
Dog: starting dose 10–20 mg/kg every 8–12 h, increase gradually if neededCats: starting dose 5–10 mg/kg PO every 8–12 hours, increase gradually if neededAbsorbed best on an empty stomach. If given for a long period animal may develop tolerance and dose may need to be increased |
(Overall, 2013; dePorter et al, 2016; Ramsey, 2017; Plumb, 2018; Sinn, 2018)
Supplements and nutraceuticals with behavioural effects
There is a wide range of supplements and nutraceutical products available that are purported to have behavioural effects. Many of these are marketed as calming agents. While many of these supplements contain ingredients that do appear to have mild calming and anxiolytic effects they are very unlikely to be sufficiently effective in animals that experience moderate to severe fearfulness or anxiety. It is also important to be aware that most supplements are not rigorously tested either for the quality of their ingredients or their efficacy. While calming supplements may play a role in helping animals that are only mildly fearful or anxious, it is important that they are not used in place of more effective medications in animals with more severe fearfulness or anxiety (van Haften et al, 2020). It is also important to check if animals are already receiving any sort of supplement before behaviourally-active medication is prescribed, as the ingredients in some supplements can interact adversely with certain behaviourally-active medications.
The role of behaviourally-active medication in the treatment of problem behaviour
While both short-acting and longer-term behaviourally active medications can play important roles in improving welfare and managing and treating problem behaviour, medication should always be part of a wider approach to addressing an animal's behaviour.
Repeated exposure to the situations that cause an animal to become fearful or anxious will lead to that fear or anxiety worsening, and the effective use of short-term medication can prevent this (Riemer et al, 2021). However it is also important to address the underlying behavioural issue itself, via reducing exposure to problem situations where possible and then teaching the animal to be more comfortable in these situations.
Animals on longer-term behaviourally-active medication will always need comprehensive behavioural support in order to help address and resolve chronic stress and underlying emotional disorders. Ideally the animal should be assessed by a suitably qualified behaviourist before medication is prescribed, to ensure an accurate assessment of their emotional state is made as this will help to inform the choice of drug. The behaviourist will also ensure a comprehensive behavioural plan is put in place to limit the animal's exposure to problem triggers, help the owner address the animal's general wellbeing and build resilience as well as helping the animal learn to be more comfortable in the particular problem situations.
Unless there is sufficient behavioural expertise within the practice to provide ongoing behavioural support the animal will need to be referred to a suitably-qualified behaviourist. Because the behaviour profession is currently unregulated it is important to check that the behaviourist has been assessed as being both academically and practically competent, such as those listed on the Animal Behaviour and Training Council (ABTC) Clinical Animal Behaviourist or Veterinary Behaviourist registers.
Before an animal is referred to a behaviourist, and also before any behaviourally-active medication is prescribed, the owner should be asked to make an appointment with a veterinary surgeon for a thorough health check. There are a number of health problems, including pain, that can cause or exacerbate a wide range of problem behaviours associated with fearfulness, anxiety and also frustration, including aggressive and abnormal repetitive behaviours (Camps et al, 2019; Mills et al, 2020). It is important that any animal presenting with a behaviour problem is given a thorough health check, and that potential underlying medical conditions are ruled out, or identified and a treatment plan put in place, before the animal is referred to a behaviourist, particularly if they are not also a veterinary surgeon.
A veterinary examination is also important before behaviourally-active medication is prescribed. Like all veterinary medicines, behaviourally-active drugs must be prescribed by a veterinary surgeon, according to the Veterinary Medicines Directorate's Prescribing Cascade, so a recent health check is a legal requirement. However this is also important to identify any health problems that might cause certain drugs to be contraindicated, as well as those that might potentially be causing or exacerbating the problem behaviour itself. The only exception would be if short-acting medication is needed to enable an animal that is fearful of the veterinary surgery or of being handled, to be examined.
Choosing the most appropriate medication for an individual animal
In the UK there are relatively few drugs licensed for the treatment of behavioural disorders in dogs, and none at all in cats. And despite the terms of some of the licenses, there are no individual drugs that are particularly suited to treating specific behavioural presentations, such as separation anxiety or sound sensitivity. This is partly because the motivations for showing problem behaviours, and the emotional responses underlying them, can vary from one individual to another, even if the behavioural responses appear similar. Animals can also vary quite significantly in how they respond to individual drugs, as also occurs in people (Preskorn, 2014). For example, one dog with signs suggestive of separation anxiety may respond well to treatment with clomipramine (Clomicalm, Novartis), while another will respond better to a different drug such as fluoxetine (Reconcile, Forte Healthcare). While most animals respond to trazodone by becoming calmer, a few animals may become hyperactive instead. This also applies to the likelihood of individuals experiencing side-effects, with some animals on a particular drug experiencing no adverse side effects at all while others can experience side-effects such as inappetence or gastrointestinal effects that are severe enough to warrant stopping the medication. Therefore, there will always be an element of trial and error when choosing behaviourally-active drugs for individual animals.
The ultimate responsibility for the choice of behaviourally-active medication for an individual animal must be made by the veterinary surgeon, based on a number of factors including:
- Legal constraints: most behaviourally active drugs are prescription only medications (POMs) and must be prescribed by a veterinary surgeon according to the Veterinary Medicine Directorate (VMD) prescribing cascade (VMD, 2021).
- The nature of the problem behaviour including the animal's motivation for doing it and the emotional response underlying it
- The animal's general health and any other medications it may be taking.
There is a more detailed discussion of how these factors will influence the decision-making process for choosing behaviourally-active medication in Warnes (2021). Part 2 of this article also includes a more detailed look at the decision-making process for choosing short-acting medication.
While the veterinary surgeon is responsible for the choice of medication, the behavioural aspects of this choice will be usefully informed by a behaviourist, and veterinary nurses can also make an important contribution through providing information given by owners about their animal's behaviour and/or their own observations of the animal's behaviour.
Conclusion
Veterinary nurses have an important role to play in ensuring animals experiencing compromised welfare receive appropriate behavioural help, potentially including behaviourally-active medication where appropriate. Veterinary nurses are often in a good position to identify the animals that might benefit from behaviourally-active medication, either through conversations with owners about their pet's behaviour or from direct observation of an animal's behaviour in the veterinary surgery. Having an understanding of the various drugs available including their behavioural effects and potential side effects will enable veterinary nurses to assist veterinary surgeons in choosing the most appropriate medication(s) for individual animals, and also to support the owners of animals that have been prescribed behaviourally-active medication. Parts 2 and 3 of this article will give more information on how they can do this.
KEY POINTS
- Behaviourally active medication can help improve welfare in animals in both the short and longer term, and can also play an important role in the successful treatment of some problem behaviours, when used alongside a comprehensive behaviour modification plan.
- An understanding of the various types of behaviourally-active drugs available and how they can be used to influence behaviour will enable veterinary nurses to assist veterinary surgeons in making the best drug choices for individual animals.
- Short-acting behaviourally-active drugs tend to have a calming effect, via reducing anxiety and/or causing sedation. They tend to work quickly and can be used as needed. However they are most effective if given before the animal becomes fearful.
- Short-acting drugs can prevent fear-related problems from getting worse by helping animals cope better with unavoidable exposure to scary situations such as loud noises, car travel, being handled in the veterinary surgery or groomers.
- Longer-term behaviourally-active drugs tend to reduce negative emotional responses, such as anxiety, fearfulness or frustration, which can reduce stress and improve wellbeing in the longer term. They have a relatively slow onset of effect, sometimes several weeks.
- Both short-acting and longer-term behaviourally-active drugs should always be used as part of a wider approach to addressing the problem behaviour including minimising exposure to problem situations where possible, and supported by a comprehensive behaviour modification plan overseen by a suitably-qualified behaviourist.