Use of clomipramine in treatment of obsessive-compulsive disorder, separation anxiety and noise phobia in dogs: a preliminary, clinical study

OBJECTIVE: To evaluate the efficacy and tolerance of a treatment protocol for obsessive-compulsive disorder, separation anxiety and noise phobia in dogs. DESIGN: A study was undertaken to assess clinical responses in 24 dogs diagnosed with one or more of three behavioural disorders stated above to a treatment regimen that included clomipramine and behaviour modification. PROCEDURE: A detailed behavioural and clinical history was obtained for each dog. Obsessive-compulsive disorder was diagnosed in nine cases: primary presenting complaints were tail-chasing, shadow-chasing, circling and chewing; one case was diagnosed with concurrent separation anxiety. Separation anxiety was diagnosed in 14 cases: presenting complaints included destruction, vocalisation and escaping in the absence of the owner; four cases also exhibited noise phobia. The study also included one dog diagnosed with noise phobia only and another with inappropriate fear responses. Clomipramine was administered orally twice daily. The starting dose was 1 to 2 mg/kg bodyweight. The dose was increased incrementally to a maximum of 4 mg/kg if needed. A behaviour modification program was designed and the owner instructed on its implementation. Dogs continued medication for at least 1 month after clinical signs disappeared or were acceptably reduced, then withdrawal of medication was attempted by decreasing drug dosage at weekly intervals while behaviour modification continued. RESULTS: The presenting clinical sign was largely improved or disappeared in 16 dogs, 5 demonstrated slight to moderate improvement and the behaviour was unchanged in 3. Clomipramine withdrawal was attempted in nine cases: this was successful in five. CONCLUSION: Clomipramine was effective and well-tolerated in controlling signs of obsessive-compulsive disorder and/or separation anxiety and/or noise phobia in 16 of 24 assessable cases, when used in combination with behaviour modification, and improvement in clinical signs was noted in 5 others.     

Clinical features and outcome in dogs and cats with obsessive-compulsive disorder: 126 cases (1989-2000)

OBJECTIVE: To determine clinical features and outcome in dogs and cats with obsessive-compulsive disorder (OCD). DESIGN: Retrospective study. ANIMALS: 103 dogs and 23 cats. PROCEDURES: Records of patients with OCD were analyzed for clinical features, medication used, extent of behavior modification, and outcome. RESULTS: Most dogs affected with OCD had been obtained from breeders. Male dogs significantly outnumbered females (2:1). Female cats outnumbered male cats by 2:1 in a small sample. Most affected dogs lived in households with 2 or more humans and other dogs or cats, and had some formal training. Client compliance with behavior modification was high. A combination of behavior modification and medication resulted in a large decrease in intensity and frequency of OCD in most animals. Clomipramine was significantly more efficacious for treatment in dogs than was amitriptyline. Only 1 dog and 1 cat were euthanatized because of OCD during the study. CONCLUSIONS AND CLINICAL RELEVANCE: OCD in dogs does not appear to be associated with lack of training, lack of household stimulation, or social confinement. In cats, OCD may be associated with environmental and social stress. Obsessive-compulsive disorder appears at the time of social maturity and may have sporadic and heritable forms. With appropriate treatment (consistent behavior modification and treatment with clomipramine), frequency and intensity of clinical signs in most dogs and cats may decrease by > 50%. Success appears to depend on client understanding and compliance and the reasonable expectation that OCD cannot be cured, but can be well controlled.     

Clomipramine-induced urinary retention in a cat

A 10-year-old, female, spayed shorthair with presumed psychogenic alopecia was treated with clomipramine (1 mg/kg body weight/day). The cat developed urinary retention within 2 days. Clomipramine was discontinued. Clinical signs resolved over the next 7 days. The urinary retention was attributed to the anticholinergic effects of clomipramine.     

Control of urine marking by use of long-term treatment with fluoxetine or clomipramine in cats

OBJECTIVES: To determine whether clomipramine differs from fluoxetine in reducing feline urine marking; whether reduction of marking continues in cats treated >8 weeks; whether recurrence of marking, after abrupt drug withdrawal, is less in cats treated >8 weeks; and whether cats that are successfully treated but resume marking after drug withdrawal can be successfully treated again with the same drug regimen. DESIGN: Positive-controlled, double-masked clinical trial. ANIMALS: 22 neutered cats (2 females, 20 males) > or =1 year old with objectionable urine marking. PROCEDURE: Cats that marked vertically > or =3 times/wk were treated with fluoxetine (1 mg/kg [0.45 mg/lb], q 24 h, PO) or clomipramine (0.5 mg/kg [0.23 mg/lb], q 24 h, PO) for 16 weeks, and efficacy was compared. Recurrence of marking was determined after abrupt withdrawal of fluoxetine at 16 or 32 weeks. Reduction in marking in cats treated with fluoxetine for 8 weeks after returning to marking following drug withdrawal was compared with the initial 8 weeks of successful treatment. RESULTS: Efficacy of fluoxetine and clomipramine was similar. Treatment >8 weeks revealed increasing efficacy in reduction of marking. Return of marking after termination of fluoxetine administration occurred in most cats. Cats successfully treated initially with fluoxetine responded similarly to repeated treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Clomipramine and fluoxetine were equivalent in treating urine marking. Longer treatment increased efficacy. Most cats return to marking after abrupt drug withdrawal. A second course of treatment can be expected to be as effective as the first.     

Effect of clomipramine on the electrocardiogram and serum thyroid concentrations of healthy cats

Clomipramine is a tricyclic antidepressant (TCA) commonly used to treat anxiety related behavioral disorders in companion animals. Tricyclic antidepressants (TCAs) have the potential to cause arrhythmias in humans and companion animals. The effect of the TCAs, clomipramine, and amitriptyline, at therapeutic dosages on cardiac rhythm has been evaluated in dogs. The effect of clomipramine on the cardiac rhythm of cats has not been reported. In Experiment 1, 7 healthy cats were selected to evaluate the effect of clomipramine on their cardiac rhythm using an electrocardiogram. A baseline electrocardiogram was carried out before (Day 0) and repeated (Day 29) after 4 weeks (28 days) of daily clomipramine (10 mg/cat PO) administration. Significant changes in the electrocardiogram were not found after 28 days of daily clomipramine administration. In Experiment 2, 7 healthy cats were enrolled in the study to evaluate the effect of clomipramine administration on the serum thyroid concentrations in cats. Clomipramine (10 mg/cat PO daily) was administered to all cats beginning on Day 1, and continued for 28 days. Serum total thyroxine (T₄), triiodothyronine (T₃), and free thyroxine (fT₄) concentrations were measured before (Day 0) and repeated (Day 29) after 4 weeks (28 days) of daily clomipramine administration. Statistically significant decreases in serum thyroid concentrations (T_4, T₃, and fT₄) were noted between pre and post clomipramine administration. A decrease of 25, 24, and 16% in serum T₄, T₃, and fT₄ concentrations, respectively, may lead to a misdiagnosis of euthyroidism in a subclinical hyperthyroid patient. A longer duration of drug treatment might further suppress thyroid function when used as a single agent, with concomitantly administered drugs, or in conjunction with euthyroid sick syndrome.     

Metronidazole neurotoxicosis in two cats

Two cats were presented for neurological dysfunction from suspected metronidazole toxicity. One cat was receiving 111 mg/kg body weight per day of metronidazole for 9 weeks. After 9 weeks, the dose was increased to 222 mg/kg body weight per day, and 2 days later the cat began to experience progressive neurological signs that culminated in generalized seizures. The second cat was receiving metronidazole at a total dose of 58 mg/kg body weight per day for 6 months. This cat experienced acute onset of ataxia and alteration in mentation. Laboratory evaluations in both cases were without significant findings. The neurological signs in both cats resolved within days of initiating supportive therapy and withdrawal of the drug. This report describes the two cases and discusses the etiology of metronidazole neurotoxicosis.     

Acetaminophen Toxicosis In 17 Cats

Seventeen cases of acetamninophen intoxication in cats were identified over a 12-year period. Information obtained from the medical records included the signalment, amount acetaminophen ingested, time from ingestion until treatment was initiated, clinical signs, physical examination, clinical pathology, treatment and outcome. The most common cause intoxication was owner administration. In cats that died or were euthanized the dose administered ranged from 10mg/kg to 17Omg/kg, while in cats that survived the dosage ranged from 10mg/kg to 400mg/kg. The most common clinical signs were depression, increased respiratory rate, respiratory distress, pale/muddy mucous membranes, and hypothermia. Twelve cats survived. Ten of these cats had treatment initiated within 14 hours after ingestion. One cat that survived had treatment initiated 24 hours after ingestion, and a second cat that survived had treatment initiated 48 hours after ingestion. Time between ingestion and initiation treatment may be as important if not more important than the actual dosage acetaminophen administered.     

Itraconazole for the Treatment of Cryptococcosis in Cats

Itraconazole was used in 35 cats with cryptococcosis. Treatment response was determined by comparing clinical signs before, during, and after treatment. It could not be evaluated in 7 cats because they died during treatment from causes unrelated to cryptococcosis. Of the remaining 28 cats, treatment response was classified as success in 16 cats (57%), as improvement in 8 cats (29%), and as a failure in 4 (14%). The failures were due to death or euthanasia from drug toxicity (1 cat), progressive fungal disease (2 cats), and relapse 1 year after treatment (1 cat). The cats that improved did not undergo a 1 -year posttreatment evaluation because they were lost to follow-up (3 cats), died or were euthanatized for other reasons (4 cats), or had a noncompliant owner (1 cat). For the 16 cats in which treatment was successful, the median itraconazole dose was 13.8 mg/kg body weight daily (range, 10.9 to 26.7 mg/kg/d), and the median duration of treatment was 8.5 months (range, 4 to 16 months). Five of these cats had previously been treated unsuccessfully with ketoconazole.     

Clomipramine and selegiline: do they influence impulse control?

Anxiety disorders in dogs are often accompanied by loss of impulse control and can result in inappropriate behaviour such as destructiveness, excessive barking and aggression. The reduction of these undesirable actions is the focus of behaviour therapy. Clomipramine and selegiline have been approved for the treatment of separation anxiety in dogs, but there are anecdotal reports that they produce inconsistent therapeutic effect. Hence, the aim of this study was to verify the efficacy of clomipramine and selegiline for regulating impulse control by using a rat model based on the delay of reward procedure. The principle is that the animal has to decide between an immediate small food reward, normally preferred by impulsive animals, and a delayed large food reward. In this study, acute effects of clomipramine (0.3-10.0 mg/kg), selegiline (0.3-3.0 mg/kg), and diazepam (1.0-3.0 mg/kg) on the impulsive behaviour of two breeding lines of rats with different anxiety-related behaviour were investigated. Neither clomipramine nor selegiline had an effect on impulse control in either breeding line. However, motor activity was decreased by clomipramine and increased by selegiline. Diazepam led to an increase in impulsive behaviour of one rat line concomitant with an increase in motor activity. The results of this rat model for studying impulsive behaviour suggest that a single administration of selegiline and clomipramine has no influence on impulsive behaviour.     

Aelurostrongylus abstrusus (cat lungworm) infection in five cats from Italy

Infection by the cat lungworm Aelurostrongylus abstrusus is considered uncommon. Here, the authors report the clinical, diagnostic and therapeutic features of five infections recently observed in Italy. All cats were under 12 months of age. All except one cat had symptomatic infections, with cough, dyspnea, and weight loss with radiographic signs of broncopneumonia. All cats were eosinophilic. Larvae were present in fresh fecal smears and on flotation exam in all cats. Baermann larval recovery permitted definitive identification and, in one case, larvae per gram of feces (lpg) counts. One dose of ivermectin (400 microg/kg) was not effective in one cat, while one dose of selamectin (6 mg/kg) was effective in one of three cases and fenbendazole at 50 mg/kg given daily for 15 days was effective in four of four cases.     

Evaluation of clomipramine as an adjunct to behavioural therapy in the treatment of separation-related problems in dogs

Forty-nine dogs showing signs of separation-related problems were randomly assigned to one of three groups: group A (15 dogs) received a placebo twice daily; group B (17 dogs) received clomipramine at 0.5 to 1.0 mg/kg twice daily; and group C (17 dogs) received clomipramine at 1.0 to 2.0 mg/kg twice daily. All the dogs also received behavioural therapy. Their owners were required to complete questionnaires about their dog's behaviour initially, and one, four and eight weeks after the treatment with clomipramine began. Bipolar ratings scales were used to monitor the frequencies of 'general', 'attachment-related' and 'separation-related' behaviours. Kruskal-Wallis tests and Kendall Rank correlations were used to determine any initial differences between the treatment groups, and the association between the initial scores and behavioural changes after one week of treatment with clomipramine. Extended Mantel-Haenszel statistics were used to evaluate the effects of clomipramine treatment versus the placebo, and Page's test was used to assess the effectiveness of behavioural therapy on its own. There were no significant differences in the demographic characteristics of the owners of the dogs assigned to the three groups. The dogs differed slightly in age between groups, and the dogs in the two clomipramine-treated groups were reported as showing problems at a significantly earlier age than those in the placebo group. Clomipramine treatment had a sustained suppressive effect on the dogs' general activity levels, and a more modest suppressive effect on their attachment-related tendency to want much physical contact with their owners. The typical signs of separation-related behaviour problems were not significantly affected by treatment with clomipramine, but behavioural therapy on its own was highly effective in reducing behavioural problems.     

Determination of the dosage of clomipramine for the treatment of urine spraying in cats

OBJECTIVE: To determine the optimal dosage of clomipramine for the treatment of urine spraying in cats. DESIGN: Randomized controlled multicenter clinical trial. ANIMALS: 67 neutered cats. PROCEDURE: Cats with a minimum 1-month history of spraying urine against vertical surfaces at least twice per week were randomly assigned to be treated with a placebo or with clomipramine at a dosage of 0.125 to 0.25 mg/kg (0.057 to 0.11 mg/lb), 0.25 to 0.5 mg/kg (0.11 to 0.23 mg/lb), or 0.5 to 1 mg/kg (0.23 to 0.45 mg/lb), p.o., every 24 hours for up to 12 weeks. Owners of all cats were given information on behavioral treatment and environmental modification. RESULTS: Prior to treatment, mean number of urine spraying events ranged from 0.9 to 1.3 urine spraying events/d for the 4 groups, and mean percentage of days with urine spraying events ranged from 62% to 69%. All 3 dosages of clomipramine were associated with significant reductions in frequency of urine spraying. Sedation was the most common adverse effect and was identified in 27 of the 50 cats treated with clomipramine; however, treatment was not discontinued in any cat because of sedation. CONCLUSIONS AND CLINICAL RELEVANCE: Results of the present study suggest that compared with a placebo, clomipramine significantly reduces the frequency of urine spraying in cats in terms of the number of urine spraying events per day and the number of days with urine spraying events. For cats with urine spraying, the recommended initial dosage of clomipramine is 0.25 to 0.5 mg/kg, p.o., every 24 hours.     

Effects of physiological covariables on pharmacokinetic parameters of clomipramine in a large population of cats after a single oral administration

This study was conducted to confirm an interindividual variability in pharmacokinetic parameters of clomipramine in a large population of cats and to identify potential covariables that would explain the presence of such pharmacokinetic variability after a single dose of Clomicalm. Clomipramine hydrochloride was administered orally according to a weight-dose chart from 0.32 to 0.61 mg/kg, to 76 cats and five blood samples were then taken by direct venipuncture at 1, 3, 6, 12, and 24 h. Plasma concentrations of clomipramine and desmethylclomipramine (DCMP) were measured by LC-MS/MS. The Standard Two-Stage technique was used to assess differences and detect correlations between pharmacokinetic parameter estimates and individual covariables. A large interindividual variability in all pharmacokinetic parameters (CV% 64-124) was detected. Statistically significant gender-related differences were detected in MR and Cl/F, where female cats had a higher mean MR (0.53) and faster Cl/F (0.36 L/h.kg) than males (0.36 and 0.21 L/h.kg, respectively). No correlation could be found between clomipramine AUC0-24 h or DCMP AUC0-24 h and sedation scores. Further feline studies are required to assess these findings after multiple dosing of clomipramine and DCMP to allow clinical extrapolation.     

Pharmacokinetics of clomipramine in dogs following single-dose and repeated-dose oral administration

OBJECTIVE: To determine pharmacokinetics of clomipramine and its principle metabolite (desmethylclomipramine) in the plasma of dogs following single-dose and repeated-dose oral administration at various dosages. ANIMALS: 9 male and 9 female Beagles. PROCEDURES: Clomipramine was administered orally at a dose of 1, 2, or 4 mg/kg to 3 male and 3 female dogs, first as a single dose and then, after an interval of 14 days, twice daily for 10 days. Plasma clomipramine and desmethylclomipramine concentrations were measured by use of a gas chromatography with mass-selection method. RESULTS: Dose-related accumulation was detected following repeated-dose administration. Accumulation ratios after administration of clomipramine at dosages of 1, 2, and 4 mg/kg twice daily were 1.4, 1.6, and 3.8, respectively, for clomipramine and 2.1, 3.7, and 7.6, respectively, for desmethylclomipramine. Terminal half-life increased slightly (1.6-fold for clomipramine and 1.2-fold for desmethylclomipramine) with repeated-dose administration but remained short in all groups (< or = 4 hours). Steady state was reached within 4 days in all animals. Ratios of the areas under the concentration versus time curves from time 0 to 12 hours for clomipramine and desmethylclomipramine were 3.9, 3.1, and 1.5 after repeated administration at dosages of 1, 2, and 4 mg/kg every 12 hours, respectively. Areas under the concentration versus time curve, mean residence times, and terminal half-lives were not significantly different between male and female dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Repeated administration of clomipramine results in higher concentrations of clomipramine than desmethylclomipramine in dogs.     

Pharmacokinetics of clomipramine and desmethylclomipramine after single-dose intravenous and oral administrations in cats

A cross-over study was performed in six adult spayed cats to determine the pharmacokinetics of clomipramine and its metabolite, desmethylclomipramine (DCMP) after intravenous (0.25 mg/kg) and oral (0.5 mg/kg) single-dose administrations. Plasma clomipramine and DCMP were measured by high-performance liquid chromatography at regular intervals for up to 30 h. Intravenous clomipramine best fit a two-compartmental model yielding an elimination rate constant of 0.037-0.09 h(-1) from which a mean half-life of 12.3 h was calculated. Mean clomipramine AUC(0--infinity) (ngxh/mL), clearance (L/hxkg), V(ss) (L/kg) and MRT (h) values were 652.5, 0.393, 5.0, and 13.5, respectively. Compartmental modeling for clomipramine, after oral administration, and DCMP after both administrations, produced wide parameter estimates and plots of residuals indicated poor goodness of fit. Noncompartmental analysis yielded mean AUC(0--30 h) (ngxh/mL), C(max) (ng/mL) and T(max) (h) of 948.3, 87.5 and 6.2 for clomipramine, and 613.8, 34.8, and 12.8 for DCMP respectively after oral administration. Clomipramine bioavailability was 90%. The present study showed marked pharmacokinetic variability for clomipramine and DCMP through biphasic absorption and potential genetic variability in clomipramine metabolism. It was concluded that population pharmacokinetics would allow better characterization of clomipramine variability that may explain the variability in clinical response noted in cats.     

The safety of high‐dose buprenorphine administered subcutaneously in cats

The safety of a proprietary formulation of buprenorphine hydrochloride administered subcutaneously (SC) to young cats was investigated in a blinded, randomized study. Four cohorts of eight cats aged approximately 4 months were administered saline, 0.24, 0.72 or 1.20 mg/kg/day buprenorphine SC for nine consecutive days, representing 0×, 1×, 3× and 5× of the intended dose. Cats were monitored daily for evidence of clinical reactions, food and water intake and adverse events (AEs). Physical examinations, clinical pathology, vital signs and electrocardiograms (ECGs) were evaluated at protocol‐specified time points. Complete necropsy and histopathologic examinations were performed following humane euthanasia. Four buprenorphine‐treated cats experienced AEs during the study, two unrelated and two related to study drug administration. The two cats with AEs considered related to drug administration had clinical signs of hyperactivity, difficulty in handling, disorientation, agitation and dilated pupils in one 0.24 mg/kg/day cat and one 0.72 mg/kg/day cat. All of these clinical signs were observed simultaneously. There were no drug‐related effects on survival, injection response, injection site inspections, body weight, food or water consumption, bleeding time, urinalysis, respiration rate, heart rate, ECGs, blood pressures, body temperatures, macroscopic examinations or organ weights. Once daily buprenorphine s.c. injections at doses of 0.24, 0.72 and 1.20 mg/kg/day for 9 consecutive days were well tolerated in young domestic cats.     

Effects of clomipramine on cats presented for urine marking

Twenty-five cats exhibiting at least four episodes of vertical urine marking per week were assessed. Following a medical workup, a 4-week clomipramine trial was instituted, using a mean dose of 0.54 mg/kg per os q 24 hours. No concurrent behavioral or environmental modifications were applied. There was a statistically significant (P<0.0001) decrease in urine spraying when the cats were on clomipramine, with 20 of 25 cats having a > or =75% reduction in spraying within 4 weeks. Side effects were mild. Twenty cats were followed for an additional 5 months. Fifteen cats required medication to control the spraying, often at a reduced dose.     

Pharmacokinetics of clomipramine in dogs following single-dose intravenous and oral administration

OBJECTIVE: To determine pharmacokinetics of clomipramine and its principle metabolite (desmethylclomipramine) in the plasma of dogs after IV or oral administration of a single dose. ANIMALS: 6 male and 6 female Beagles. PROCEDURES: Clomipramine was administered IV (2 mg/kg), PO (4 mg/kg) after food was withheld for 15 hours, and PO (4 mg/kg) within 25 minutes after dogs were fed. Plasma clomipramine and desmethylclomipramine concentrations were measured by use of a gas chromatography with mass-selection method. RESULTS: Time to peak plasma concentrations of clomipramine and desmethylclomipramine following oral administration was 1.2 hours. For clomipramine, after IV administration, elimination half-life was 5 hours, mean residence time was 3 hours, and plasma clearance was 1.4 L/h/kg. Values for mean residence time and terminal half-life following oral administration were similar to values obtained following IV administration, and systemic bioavailability was approximately 20% for clomipramine and 140% for desmethylclomipramine, indicating fast absorption of clomipramine from the gastrointestinal tract and extensive first-pass metabolism. Administration of clomipramine with food did not alter the area under the concentration versus time curve for desmethylclomipramine but resulted in a 25% increase for clomipramine. Clomipramine and desmethylclomipramine were extensively bound (> 96%) to serum proteins. There were no significant differences in area under the concentration versus time curve between male and female dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that there should not be any clinically important differences in efficacy regardless of whether clomipramine is administered with or without food.     

Toxicologic evaluation of chlorpyrifos in cats

Twenty-four male domestic shorthair cats were used to evaluate the acute and chronic effects of a single, toxic but sublethal, orally administered dose of chlorpyrifos. A dosage of 10 mg/kg of body weight did not induce clinical signs of toxicosis, but a dosage of 40 mg/kg induced clinical signs of toxicosis, and 1 of 12 cats died. Chlorpyrifos given at a dosage of 0.1 mg/kg to 2 cats reduced whole blood and plasma cholinesterase (Che) activities to values obtained after cats were given doses that induced clinical signs of toxicosis. Regeneration time for whole blood and plasma Che activities ranged from 7 to 28 days. Brain Che activity was considerably decreased in 1 cat that died 4.5 hours after dosing, but was normal in all others at 28 days after dosing. Other than decreased Che activity, significant changes were not seen in hematologic or serum biochemical values. Toxin-related lesions were not seen during macroscopic or microscopic examination.     

Use of doramectin for treatment of notoedric mange in five cats

Five of 16 cats belonging to the same owner were brought to the veterinary hospital because of a 30-day history of signs of intense pruritus and alopecic and erythematous areas with bloody crusts. Notoedric mange was diagnosed and confirmed by microscopic examination of skin scrapings of all 5 cats. The remaining cats did not have clinical signs of mange, and Notoedres cati were not observed after microscopic examination of skin scrapings. A decision was made to treat all 16 cats with doramectin subcutaneously. In each cat, 0.1 ml of a 1% solution of doramectin was administered s.c. Body weights ranged from 2.9 to 7.1 kg (6.4 to 14.2 lb) in the 16 cats and the final doses varied from 143 to 345 micrograms/kg (65 to 157 micrograms/lb) of body weight, with a mean (+/- SD) of 270.4 +/- 64 micrograms/kg (122.9 +/- 29.1 micrograms/lb). The mean dose for the 5 affected cats was 292.2 +/- 44.8 micrograms/kg (132.8 +/- 20.4 micrograms/lb), with a range of 208 to 333 micrograms/kg (94.6 to 151.4 micrograms/lb). Lesions began to recede 1 week after treatment. Fifteen days after treatment, all 5 affected cats were clinically normal. Findings in our cats suggest that a single mean dose of doramectin of approximately 290 micrograms/kg is sufficient to control notoedric mange in cats.