The use of drugs to treat behaviour problems in animals (psychopharmacology) is in its infancy. Much of the available data is anecdotal, based on individual clinical cases treated successfully (unsccessful cases are not written up). The drugs used are usually not registered for use in animals. There is a tendency to prescribe drugs used in the treatment of human psychiatric disorders for the treatment of animals but there have been very few trials in which the use of such drugs in cats and dogs was examined. Behavioural treatment should be used in combination with drugs. Beware side effects: many of the drugs used to alter behaviour act on monoamines, an effective overdose of noradrenaline or 5HT can have severe cardiovascular effects (serotonin syndrome).
Anxiolytic drugs, antidepressants and progestins have been used. They reduce the anxiety and stress being experienced by the cat. This allows the cat time to become habituated or desensitized to the stressor and the owner time to modify the environment to reduce the stressor. Drugs assist in the treatment of inappropriate marking but may be ineffective if used without environmental modification.
Many drugs are used to reduce anxiety in humans. The definition of anxiety in domestic animals remains unclear but it is widely accepted that inappropriate marking in cats is often due to anxiety. The most commonly used anxiolytic in the cat is diazepam (Valium) 1 to 2 mg/cat (0.2 - 0.4mg/kg) twice daily for 4 weeks then once daily for 4 weeks thereafter decreased by half for each week in the third month. Many cats revert to inappropriate marking when administration of diazapam is stopped. Diazepam improves the problem of inappropriate marking in 55 to 75% of cats treated and is as effective in males as females. Longer acting benzodiazepines, lorazepam, oxazepam or clonazepam may also be useful in the treatment of inappropriate marking (Stogdale, 1992).
Sedation may leave the cat more vulnerable to road traffic accidents and predatory dogs. Increased appetite and weight gain are common. Interestingly, increased affection is regularly seen. Fatal hepatic toxicity has been reported in cats within 11 days of receiving diazepam.
Buspirone is a 5HT1A antagonist used as an anxiolytic in people. It may be effective in the treatment of inappropriate marking in cats (0.5 - 1mg/kg po 2 - 3 times daily). Buspirone has little sedative effect and appears to produce little tolerance in humans. It does not cause withdrawal symptoms. If the cat does not respond to treatment then use something else. Buspirone was effective in 55% of cats treated by Hart et al. (1993).
Tricyclic antidepressants are the most commonly used drugs in the treatment of depression in humans. They do not interfere with short term memory and thus are useful in behaviour therapy in animals. Amitriptyline, clomipramine and fluoxetine are commonly used. Treatment should continue for 2 to 3 weeks after the undesirable behaviour has stopped. The medication should then be gradually reduced over an eight week period. Amitriptylline stopped inappropriate marking in 80% of cats (Stogdale, 1992). Sleepiness was seen initially but it wore off during the first two weeks of treatment.
Progestins, such as megoestrol in tablet form and medroxyprogesterone in injectable form, have antiandrogenic and antianxiety effects. They are commonly used for sexually dimorphic problems which have not responded to neutering. They may work by selective binding to sites in the hypothalamus which reverse the action of testosterone sensitive action centres. They should not be used initially in the treatment of inappropriate marking because of their side effects.
In the treatment of inappropriate marking it is the antianxiety effect of progestins which is utilised. They are reported as being effective in about 30 to 50% of neutered cats however other reports conclude that they are effective in 48% neutered males and 18% spayed queens. If the treatment is successful then results should be seen within the first week after initiation (Halip et al, 1992). It has been suggested that if megoestrol acetate doesn't work then medroxyprogesterone may or vice versa. Progestins should be used as a last resort since the risk of side effects is high.
here are several different types of aggression and it is important to diagnose the cause of aggression before initiating treatment. In addition the social milieu in which aggression occurs must be considered before treatment is embarked upon. Behavioural therapy and castration are often effective in reducing or eliminating aggression but on occasion drugs are needed to supplement these forms of therapy. Painful conditions especially those of the ears, shoulders and hips are probably more important in the development of aggression than we usually recognise. Male aggression, especially intermale aggression, may respond to castration. If castration is not possible or if aggression continues afterwards then progestins (medroxy- progesterone) may be effective.
Acepromazine tablets may be effective in the short term control of aggression (0.5 - 2.0 mg/kg every 8 to 36 hours).
The anti androgenic progestagen delmadinone (Tar- dak) may also be effective. It is thought to work by inhibiting pituitary gonadotrophin release and by affecting a behavioural (sex) centre. The effects are reversible. Dose dogs <10kg - 1.5 - 2.0 mg/kg, 10 to 20kg - 1.0 - 1.5 mg/kg, >20kg - 1 mg/kg bodyweight by sc or im injection. An effect should be seen within 5 days. If not seen within 8 days repeat treatment. Otherwise repeat treatment at 3 to 4 weeks. Thereafter repeat as required. Do not use in dogs with history of poor libido or poor fertility if such dogs are to be used later for stud purposes. Do not use if other steroids are being given.
The use of diazepam for the treatment of fear aggression in dogs is not recommended as it sometimes acts to cause aggression by, it is speculated, reducing fear.
The obsessive-compulsive behaviour in dogs which include tail chasing (Bull Terrier types), flank sucking (Doberman), fly biting (Cavalier King Charles Spaniels) and acral lick granuloma are similar to stereotypic behaviour seen in humans such as hair pulling and hand washing. The pathological background to these activities remain ill defined but it is believed that aberrant serotonin metabolism is involved although some attribute the activity to abnormal endorphin metabolism. It is suggested that the anatomical focus of the disorder is the limbic system and studies have implicated the basal ganglia in the region of the caudate nucleus in humans.
Obsessive compulsive behaviours are characterised by being repetitive behaviours in excess of requirements and often interfering with normal activities. Differential diagnosis of obsessive compulsive behaviour in dogs include the following;
Obsessive compulsive behaviour may be the appro- priate diagnosis if the dog or cat does not respond to the therapies discussed above and if it interferes with normal behaviour.
Obsessive compulsive behaviour disorders have been treated with tricyclic antidepressants; amitriptyline (1-2 mg/kg twice daily for dogs); clomipramine (can cause arrhythmias and should be used only after the dog has had a thorough cardiac examination). Because it is potentially dangerous, treatment should start at about 0.5mg/kg every 12 hours increasing over a 5 week period to 3mg/kg or 200mg per day whichever is less. Should any side effects develop the treatment should be stopped or the dosage reduced. Usually treatment should last for 5 weeks to determine how succesful it is. If clomipramine is successful it will have to be continued for life. Imipramine and fluoxetine (0.5 - 1mg/kg once daily) have also been used, as has doxepin 3-5mg/kg orally every 12 hours increasing to a maximum of 150mg/kg every 12 hours. The minimum dose is given for 10 days and should be doubled if no effect seen.
A common problem in young dogs and may be expressed as persistent barking or destruction / digging when the owners are absent. This type of anxiety is usually treatedby counter-conditioning and habituation. However counter conditioning for the treatment of anxiety is usually more successful if combined with medication. Two drugs considered to be particularly useful in the treatment of seperation anxiety in dogs are; clomipramine (1 - 2mg/kg twice daily) and amitriptyline (1-2 mg/kg twice daily). Both are very useful for dogs which bark or groom excessively when alone. Usually given about 1 hour before everyone leaves the home. Treatment continued for up to 3 months and then tailed off gradually. Fluoxetine (1mg/kg once or twice daily) is also useful.
Diazepam given before or during a storm may be useful in reducing the expression of the phobias. However diazepam does change some dogs behaviour for the bad and they may become aggressive and destructive. Use with cau- tion in nervous dogs!
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K.J.Stafford
