1447, 1448.qxd

Clinical features and outcome in dogs and cats
with obsessive-compulsive disorder:
126 cases (1989–2000)
Karen L. Overall, VMD, PhD, DACVB, and Arthur E. Dunham, PhD ning, fly biting, self mutilation, hair or air biting, pica,pacing or spinning, staring and vocalizing, some aggres- Objective—To determine clinical features and out-
sions, self-directed vocalizing, and fabric sucking or come in dogs and cats with obsessive-compulsive chewing. In cats, self-mutilation, excessive grooming, tail chasing, and wool or fabric sucking or chewing are Design—Retrospective study.
also signs of OCD.1-6 Because behaviors seen in OCD are Animals—103 dogs and 23 cats.
often normal behaviors performed in an inappropriate, Procedures—Records of patients with OCD were
excessive, or out-of-context manner,7,8 history becomes analyzed for clinical features, medication used, extent particularly important in elucidating whether the patient truly has OCD. The purpose of this retrospec- Results—Most dogs affected with OCD had been
tive study was to determine clinical features, response obtained from breeders. Male dogs significantly out- to treatment, and outcome in dogs and cats with OCD. numbered females (2:1). Female cats outnumberedmale cats by 2:1 in a small sample. Most affected Criteria for Selection of Cases
dogs lived in households with 2 or more humans All dogs and cats seen at the Behavior Clinic of the and other dogs or cats, and had some formal train- University of Pennsylvania from January 1989 through ing. Client compliance with behavior modification December 2000 were assessed for OCD as part of a was high. A combination of behavior modification thorough history and by use of a standardized ques- and medication resulted in a large decrease in inten- tionnaire.8,a Inclusion criterion was a diagnosis of OCD sity and frequency of OCD in most animals.
made on the basis of finding repetitive, stereotypic Clomipramine was significantly more efficacious fortreatment in dogs than was amitriptyline. Only 1 dog motor, locomotory, grooming, ingestive, or hallucino- and 1 cat were euthanatized because of OCD during genic behaviors that occurred out of context or in fre- quency or duration in excess of that required to accom- Conclusions and Clinical Relevance—OCD in dogs
plish the ostensible goal or in a manner that interfered does not appear to be associated with lack of training, with the animal’s ability to function in its social envi- lack of household stimulation, or social confinement.
ronment.7,9,10 As a result of the standardized screening In cats, OCD may be associated with environmental of all patients, the diagnosis of OCD was made for and social stress. Obsessive-compulsive disorder some patients for whom the affiliated behaviors were appears at the time of social maturity and may have not the clients’ primary complaint, and in a few ani- sporadic and heritable forms. With appropriate treat- mals the diagnosis of OCD was secondary to another ment (consistent behavior modification and treatment primary condition (eg, obsessive-compulsive spinning with clomipramine), frequency and intensity of clinical and barking that is particularly performed during signs in most dogs and cats may decrease by > 50%.
Success appears to depend on client understanding and compliance and the reasonable expectation thatOCD cannot be cured, but can be well controlled. Procedures
(J Am Vet Med Assoc 2002;221:1445–1452) From the medical records, patients were classified by breed; weight; sex and neuter status; age at neuter-ing; age at onset of OCD; source; number of humans, Obsessive-compulsive disorder (OCD) in pet dogs cats, and dogs in the household; training or schooling;
and cats is usually recognized because of a com- duration of treatment; class of OCD (hallucinatory, pulsive component (ritualistic, stereotypic behaviors).
vocalization, locomotory, grooming or self-mutilation, Obsessive-compulsive behaviors in dogs can include ingestion [pica or coprophagy])1-6,11; whether other those characterized by circling, tail chasing, flank suck- dogs or cats in the household had the same or similar ing (particularly in Doberman Pinschers), fence run- behavior and if so, which animals; concurrent behav-ioral diagnoses; medication used and duration; extent From the Biology Department (Dunham) and the Center for Neurobiology and Genetics-Psychiatry Department, School of Medicine (Overall), University of Pennsylvania, Philadelphia, For assessment of animal age and duration of OCD, actual birth dates were used when known. If the Data entry was supported by Novartis Animal Health, Greensboro, day was unknown but the month of birth was known, NC; medication for some patients was provided by CIBA, Summit, the patient was assigned a birth day of 15. If both NJ, and Novartis Animal Health, Greensboro, NC.
month and day were unknown, the patient was The authors thank Len Rhone and Ken Mullin for technical assis- assigned a birth date of June 30 of the year suspected Address correspondence to Dr. Overall.
JAVMA, Vol 221, No. 10, November 15, 2002 Sources of animals included stray or found, breed- intensity and frequency of OCD behaviors), administra- er (serious or show), breeder (backyard), Society for tion of the drug was maintained and treatment was con- the Prevention of Cruelty to Animals or humane shel- sidered successful. If a patient was treated initially with ter, breed rescue service, newspaper adoption adver- amitriptyline and acceptable results were not obtained, tisement (not breeder), pet store, friend, and other.
clomipramine was administered instead; if acceptable Training or schooling categories included no school, results were obtained with clomipramine, treatment trained by client, puppy kindergarten, group lessons with amitriptyline was considered a failure and treat- (basic), group lessons (advanced), private trainer at ment with clomipramine was considered a success.
house, and private trainer (sent to trainer). Patients for whom treatment with clomipramine failed The general behavior modification scheme for dogs were likewise treated with another medication. consisted of 3 basic steps designed to stop unwanted Dosage protocols13 were used consistently and behaviors and reward preferable behaviors that were included amitriptyline (1 mg/kg [0.45 mg/lb], PO, q 12 directly competitive with the undesirable behaviors. In h for 10 days; if no change in behavior was detected, step 1, clients were to cease even unintentional reward the dosage was increased to 2 mg/kg [0.91 mg/lb] for for the undesirable behavior. In step 2, clients were 10 days; if still no change was detected, the medication asked to follow a passive behavior modification pro- was changed [if treatment was efficacious it was con- gram designed to teach dogs to sit quietly, look at the tinued for a minimum of 1 month]); doxepin (3 to 5 person from whom they were seeking attention or with mg/kg [1.4 to 2.3 mg/lb], PO, q 8 h to q 12 h for a min- whom the interaction was occurring, and wait to take imum of 1 month); clomipramine (1 mg/kg, PO, q 12 the cues about the appropriateness of their behavior h for 14 days, then 2 mg/kg, PO, q 12 h for 14 days, from those people (ie, Protocol for Deference8). In step then 3 mg/kg, PO, q 12 h for 1 month, for a minimum 3, clients were requested to begin active behavior mod- of 2 months of treatment [the gradual increase in ification designed to teach the dogs to relax when they dosage was intended to minimize gastrointestinal dis- would otherwise be engaged in the behavior, in orders]); and the SSRIs, sertraline and fluoxetine (1 exchange for which the dog was given a food or play mg/kg, PO, q 24 h for 2 months initially). Treatment reward (ie, Protocol for Relaxation: Tier 18). was then continued at the minimum effective dose nec- For clients with feline patients, steps 1 and 3 were recommended; step 2 was modified to recommend that All patients received full physical and laboratory the client only interact with the cat when the cat was evaluation prior to treatment. Any nonspecific derma- calm. Cats were not required to sit in step 3, although tologic, medical, or neurologic signs potentially associ- this was encouraged, but the clients were advised to ated with OCD were evaluated by the veterinarians engage the cat in an enjoyable behavior that was direct- trained in the respective specialty prior to behavioral ly competitive with the undesirable behavior. treatment. When warranted, patients also received var- Behavior modification was assessed on the basis of ious nonroutine diagnostic procedures (eg, assessment of thyroid function and magnetic resonance spec- For some of the patients, medication had been pre- scribed by the referring veterinarian. When the first Eight clinicians were involved in evaluation of the patient in this study was treated, treatment with tricyclic
dogs reported here. All clinicians adhered to the same antidepressants (TCAs; eg, clomipramine and specific
diagnostic criteria, and at least 2 clinicians reviewed each serotonin reuptake inhibitors [SSRIs]) was cost pro-
diagnosis. Although many records contained detailed out- hibitive (> $10/d). Clomipramine is now affordable and come data, quality of the description of the behaviors available in a canine formulation.b Accordingly, the TCA depended on clinician expertise versus resident expertise, (amitriptyline) was the first drug of choice for all whether the behaviors were videotaped, client capability patients with conditions that primarily involved anxiety and motivation in keeping data logs, and knowledge and were enrolled in the early portion of the study.
accrued by managing increasing numbers of these dogs.
Clomipramine was only used instead of amitriptyline if Accordingly, outcomes were broadly grouped and statisti- amitriptyline was not efficacious or caused gastrointesti- cally treated as class variables to evaluate older and newer nal disorders. Because of its histamine-1 receptor antag- cases equivalently. Response variables for outcome were onist properties, the TCA doxepin was the first drug of small decrease in intensity (≤ 50%), large decrease in choice for conditions that primarily involved pruritus, intensity (> 50%), small decrease in frequency (≤ 50%), followed by amitriptyline.8,12-14 Other medications were large decrease in frequency (> 50%), the behavior stopped occasionally prescribed as dictated by alterations in the totally, no change, small increase in intensity (< 50%), patients’ behaviors, and for some animals, combinations large increase in intensity (> 50%), small increase in fre- of medications were both more efficacious and more quency (< 50%), large increase in frequency (> 50%), cost-effective for clients, as described elsewhere.13 died, euthanatized because of OCD, euthanatized for When the senior author was awarded a grant pro- other reasons, placed, other, and unknown. Patients clas- viding clomipramine at no cost, clomipramine was used sified with unknown outcomes were those lost to follow- as the first drug of choice for treating OCD, as it has up. For patients with concurrent behavioral diagnoses, been in humans. This circumstance allowed us to retro- alterations in intensity and severity reported here pertain spectively compare the relative effects of amitriptyline and clomipramine for patients that met the criteria for Data were analyzed by use of the log-likelihood OCD. If a patient was administered amitriptyline and ratio test, and relevant nonparametric tests as indicat- acceptable results were obtained (marked decrease in 1446 Scientific Reports: Retrospective Study JAVMA, Vol 221, No. 10, November 15, 2002 There was no significant association (log likeli- One hundred three dogs met inclusion criteria, hood ratio test) between sex and neuter status catego- including 5 sexually intact females, 26 spayed females, ry of affected dogs and the category of OCD they had.
20 sexually intact males, and 52 neutered males.
However, compared with the sex and neuter data for Twenty-three cats (1 sexually intact female, 14 spayed the entire veterinary teaching hospital canine popula- females, 1 sexually intact male, and 7 neutered males) tion during the study period (n = 47,473), male dogs that met the diagnostic criteria had sufficiently com- were significantly over-represented in the OCD popu- plete records to be included in the study.
lation (log likelihood ratio test statistic, Gadjusted (adj) =13.256 [P < 0.05]). In addition, neutered males were Category of OCD—The most common category of
over-represented in the OCD population, compared OCD in dogs was that associated with grooming or with non-neutered males (log likelihood ratio test sta- self-mutilation, followed by OCD involving locomo- tion and OCD involving signs of hallucinations (Fig 1).
For cats, the most common category of OCD involved Breed—The population of dogs with OCD com-
grooming or self-mutilation (Fig 2).
prised 18 mixed-breed dogs; 12 German ShepherdDogs; 7 Rottweilers; 6 Golden Retrievers; 5 each ofDalmatians, Labrador Retrievers, and Lhasa Apsos; 3each of Doberman Pinschers, Poodles, Soft-CoatedWheaten Terriers, and English Springer Spaniels; 2each of American Pit Bull Terriers, Bulldogs, GreatDanes, Miniature Schnauzers, and Cocker Spaniels;and 1 dog each of 22 other breeds. This distributiondid not differ significantly from that in the overallcanine population of the Behavior Clinic or of the vet-erinary teaching hospital. Further examination of themost common breeds of dogs (mixed breeds, GermanShepherd Dogs, Rottweilers, Dalmations, andBulldogs) revealed interesting patterns among thebreeds. The specific manifestations of the OCDappeared to be associated with the tasks for which thedogs were developed. Dogs of herding breeds often hadexcessive tail chasing. Dogs of guarding breeds andthose selected for intense focus and tenacity (eg,Dalmatians, Rottweilers, and German Shepherd Dogs)often had signs of hallucinations. All Rottweilers andall but 1 Dalmatian had signs of hallucinations. Nine of Figure 1—Frequency (%) distribution of categories of obsessive- 12 German Shepherd Dogs chased their tails. compulsive disorder (OCD) in 103 dogs. M = Self-mutilation The cat population consisted of 14 Domestic (grooming). L = Locomotor (spinning, chasing). H = Hallucinatory. Shorthairs, 6 Siamese, 1 Devon Rex, 1 Russian Blue, P = Pica. V = Vocalization. K = Licking. C = Coprophagy. S =Sucking. D = Digging. O = Other.
and 1 Bengal. Siamese cats commonly had pica involv-ing sucking, chewing, or ingestion of fabrics; 2 of the 6Siamese cats in the study chewed, sucked, or ingestedfabric; and 1 ingested electric cords. All cats thatingested fabric were Siamese, but neither cats thatlicked plastic substrate or had sucking behavior cate-gory were. The Bengal cat had over-grooming andurine marking, both anxiety-related conditions. Thesmall number of cats we evaluated precluded statisticalcomparisons among breeds. The behaviors associatedwith OCD appeared after trauma in 3 cats and afterchanges in feline or human social circumstances orrelationships in 7 cats. The changes in the feline orhuman relationships were also often associated withintercat aggression or elimination abnormalities (9cats). Grooming or self-mutilation involved 16 of thecats, 3 of which had a previous diagnosis of hyperes-thenia and 3 of which had a diagnosis of atopy. Age of onset—Age of onset was known or confi-
dently estimated for 95 of the 103 dogs. Mean ± SD ageat onset was 20.3 ± 23.7 months; however, the fre-quency distribution of age at onset was highly skewed Figure 2—Frequency (%) distribution of categories of OCD in 23 (skewness, 3.214). Age of onset for cats was 28.2 ± 30.1 months (n = 21), and the frequency distribution JAVMA, Vol 221, No. 10, November 15, 2002 was less skewed (skewness, 1.14) than that of the dogpopulation. Median age of onset for cats and dogs was12 months, indicating that half of the patients devel-oped signs of OCD by the age of 1 year.
Source—Almost 60% of the dogs in this study
originated from either serious show breeders (54.4%) or backyard breeders (4.9%). These categories wereself-assigned by the dog owners, so the low percentageof backyard breeders may have been an underestimate.
Only 9% of dogs came from pet stores, whereas 11%came from humane shelters. Six of the cats came from friends, 5 came from either serious show breeders or backyard breeders, 5were found or were stray, 3 came from humane shel-ters, and 4 came from miscellaneous sources. Size of human and pet households—Only 18
(17.5%) of the dogs in this study lived in single-humanhouseholds; 46 (44.7%) lived in households with 2humans, and 39 (37.7%) lived in households with 3 ormore humans. More than half of the dogs in this studyhad other dogs in the household, and almost 30% had Figure 3—Outcomes for 103 dogs treated for OCD. SDI = Smalldecrease in intensity of OCD (≤ 50%). LDI = Large decrease in intensity (> 50%). SDF = Small decrease in frequency of OCD Most of the cats lived in households with 2 or behavior (≤ 50%). LDF = Large decrease in frequency (> 50%).
more humans (n = 18). Fifteen cats lived with other S = Stopped OCD behavior completely. NC = No change.
cats; 11 lived in 2-cat households, and 4 lived in house-holds with 3 or more cats. Few cats (n = 3) with OCDhad dogs in their household. Training for dogs—Most dogs in this study had
what is considered to be basic training of some kind; 6(5.9%) attended puppy kindergarten, 20 (19.6%)attended basic group lessons, 10 (9.8%) attendedadvanced group lessons, 17 (16.7%) had a privatetrainer come to their house, and 3 (2.9%) were sent toa private trainer. Client compliance with treatment—Only 3% of
canine clients admitted to performing none of thebehavior modification. For 17% of the patients, com-pliance data were unavailable. Sixty-three percent ofthe clients either complied extensively (38%) or con-sistently (25%). Twenty percent complied intermittent-ly. Client compliance for treatment in cats was alsohigh. Treatment outcomes for dogs and cats were calcu- lated (Fig 3 and 4). Percentage frequencies of dogs
with large decreases in intensity and dogs with large
Figure 4—Outcomes for 20 cats treated for OCD. See Figure 3 decreases in frequency of behavioral problems were significantly associated (Cochran-Mantel Haenzel teststatistic Gadj = 59.87; df = 1; P < 0.001). Other out- (0.59) for amitriptyline (log likelihood ratio test statis- comes included unknown (14 dogs were lost to follow- up), small increase in intensity but a large decrease in frequency of episodes (n = 1), death unrelated to OCD Duration of treatment—Dogs for which complete
(1), euthanasia for OCD (1), and euthanasia for rea- information was available (n = 80) were treated for a mean of 14.1 months, a median of 12 months, and a rangeof 6 to 78 months. Cat data were insufficient for analysis, Efficacy of medication—Of the 103 dogs in this
but the range of continuous treatment was 2 to 4 months.
population, 84 were treated with 1 or more drugs.
All cats from which medication was withdrawn (n = 9) Nineteen clients declined a drug treatment option for relapsed and drug treatment was reinstated. their dog. There were sufficient data only to comparethe relative success rates for amitriptyline and Affected relatives—Clients knew whether rela-
clomipramine (Table 1). The observed success rate for
tives were also affected with some form of OCD for clomipramine (0.83) was significantly greater than that only 30 of the 103 dogs in this study; 15 dogs had 1448 Scientific Reports: Retrospective Study JAVMA, Vol 221, No. 10, November 15, 2002 Table 1—Drug treatment and evaluation of success versus fail- Discussion
ure in 89 dogs and 20 cats with obsessive-compulsive disorder Stereotypic behaviors may or may not be associat- ed with OCD.1-5,7 Differential diagnoses for other Probability
behavioral conditions in which the nonspecific signs Successes
Failures
of success
associated with OCD can occur include environmental causes, management, humane considerations (eg, those involving understimulation, neglect, or excessive , generalized anxiety, and hyperactivity.7,8 Obsessive-compulsive disorder in all species is tion of which interferes with normal, daily activities behavior that is exaggerated in form as well as dura- tion. The diagnostic criteria employed here have dual *Used in combination with clomipramine to treat signs of panic. †Used for advantages. First, they permit separation of nonspecif- pruritus associated with lesion caused by grooming in cats. ‡Used for pruri-tus associated with lesions caused by grooming in dogs. §For treatment of ic signs from diagnostic criteria. This allows the non- putative intervertebral disk disease. IIUsed in combination with amitriptyline specific signs to be used to evaluate changes in the con- (2 animals) and clomipramine (1 animal) for signs of panic.
dition and to further describe populations afflictedwith different manifestations of the condition.15,16 affected relatives and 15 did not. Of the 15 dogs with Second, they do not require definition or assessment of affected relatives, 7 had 1 known affected relative (3 underlying motivational states, which is difficult to male littermates, 3 sires, and 1 dam), 7 had 2 known accomplish in a meaningful manner in other species.
affected relatives (female littermate-male littermate, It appears that dogs, as do humans, may perceive sire-male offspring, sire-other, grandsire-other, dam- that their behaviors are abnormal and control their male littermate, dam-second degree relative), and 1 behaviors to the extent that the behavior is performed had 3 known affected relatives. Only 3 clients with cats only minimally, or not at all, in the presence of others.
knew about affected relatives, and only 2 of these defi- Dogs who flank suck or tail chase may, after frequent nitely had an affected relative (1 sire, 1 offspring). reprimands and corrections, remove themselves fromview and then commit the behavior elsewhere. Upon Concurrent behavioral diagnoses—Seventy-seven
approach, the behavior ceases, only to begin again (74.8%) dogs had concurrent behavioral conditions, as when no one is watching or when the animal removes determined via published diagnostic criteria.8 Thirty- itself from view. Results of this study support the exis- three (32.0%) dogs met the criteria for a diagnosis of tence of this evasive behavior pattern. If the desire to attention-seeking behavior (eg, excessive solicitation perform the behavior is present, despite restraint and neediness), 29 (28.2%) met the criteria for a diag- because of punishment, training, or physical incarcer- nosis of dominance or impulse-control aggression, 23 ation, the condition is present. The key is that if such (23.3%) met the criteria for a diagnosis of separation control is removed and the animal can commit the anxiety, and 16 (15.5%) met the criteria for a diagnosis behavior, it will commit the behavior. Ignoring this of generalized anxiety disorder. Thirty other miscella- crucial point will result in underdiagnosis of OCD and neous behavioral and medical diagnoses were also underestimation of its frequency in canine and feline noted. There was no association between duration that the dog had been affected before treatment and the The presence of this and other cognitive compo- number of concurrent behavioral diagnoses (r = 0.13; nents suggests that the problem is rooted at a higher P = 0.23). Because many dogs in this study had multi- level than the behavior alone may indicate (ie, a ple concurrent behavioral diagnoses, the sample sizes of Doberman Pinscher may be flank sucking, but not each diagnostic combination were insufficient to deter- because anything is wrong with its flank). Such exam- mine whether the associations were random, as has ples support the contention that obsessions are a valid been performed elsewhere.15 The data were also insuffi- component of OCD. We evaluate obsessions in cient to assess whether dogs that had been affected humans by asking them about repetitive, invasive longer had more intense or more frequent signs of thoughts.17 It is inappropriate to apply a criterion (eg, OCD, compared with dogs affected for a short period. assessment that relies on a verbal response) to 1 In contrast with dogs, only 9 of 23 (39.1%) cats species that has a divergent phylogeny (eg, nonverbal) met the criteria for concurrent behavioral diagnoses, a that prohibits the use of that tool or criteria.10 The difference that was significant (log likelihood ratio test, extent to which the patients in our study focused on Gadj = 10.04; P < 0.05). In contrast with dogs, most of their behaviors, avoided those who sought to interfere the concurrent behavioral diagnoses were associated with them, and were avoided by clinically normal or with elimination disorders; 3 cats also sprayed, 2 cats unaffected canine and feline housemates strongly sug- urine-marked without spraying, 1 cat marked with gests that a cognitive component was present, albeit feces, and 1 cat had a substrate aversion to the litter.
Only 1 cat met the criteria for separation anxiety, a Obsessive-compulsive disorder in humans fre- quently appears in adolescence, at the onset of social JAVMA, Vol 221, No. 10, November 15, 2002 maturity, and continues through midlife. In dogs and nonspecific sign of an anxiety-related condition. This cats, OCD also appears during this indistinct period of finding supports the hypothesis that OCD in dogs is social maturity (range for dogs, 12 to 36 months; based in some primary neurochemical or neurogenetic mean, approx 18 to 24 months; range for cats, 24 to 48 dysfunction, and that the mechanisms driving OCD months; mean, approx 30 to 36 months)8 and if left untreated, whether by behavioral or pharmacologic Obsessive-compulsive disorder affects at least 2% intervention, it worsens. Given the relatively early age of the human population, and this is believed to be an at which this condition develops and the probability of underestimate.19-21 Some forms of OCD have a familial profound deterioration when left untreated, young ani- genetic component22-24; however, most instances of mals should be routinely screened for OCD and treat- human OCD appear to be sporadic. It is important to ed appropriately early. Dogs and cats from families recognize that the development of specific animal with a history of OCD should be carefully watched for breeds and the practice of inbreeding within those its appearance, albeit possibly in a different form than breeds suggest that the prevalence of OCD in dogs could be higher than that reported for humans. In this study, 10 of the 23 affected cats had signs of On the basis of client interviews and complaints, their particular form of OCD after some physical trau- OCD may be familial in Great Danes, German Short- ma or social upheaval, and the OCD in these cats may haired Pointers, German Shepherd Dogs, Bull have occurred concomitant with intercat aggression or Terriers,25 Jack Russell Terriers, Dalmatians, Bouvier de elimination problems. Siamese cats were ranked as the Flanders, Salukis, Cairn Terriers, Basset Hounds, and second most common breed in this study. Although Soft-Coated Wheaten Terriers.10 The strong correla- this does not differ substantially from their rank in the tions between canine breeds and forms of OCD we overall hospital population (3), it is dramatically dif- detected strongly suggest a genetic basis for OCD, ferent from the breed rank in our Behavior Clinic pop- albeit, in part as the result of genetic limitations and ulation (22), suggesting that when a Siamese cat is subsequent potential decreases in genetic heterogene- evaluated because of a behavioral problem, the behav- ior is likely associated with OCD. Siamese cats were As is true for humans, first-degree relatives usual- most often involved in ingestion of fabric, supporting ly have a different form of OCD than the proband, other findings regarding increased prevalence of OCD which supports the hypothesis of a heritable, neuro- in Oriental-breed cats,18 but there were too few mem- chemically variable basis for OCD. That 50% of the bers of each breed to reach breed-related conclusions.
dogs in this study for which familial data were known It is interesting that the only Bengal cat in the study had a relative affected with some form of OCD strong- population had self-mutilation and urine marking.
ly suggests 2 important points: certain breeds of dogs These are both anxiety-related conditions and may appear to have a high prevalence of OCD, perhaps have some association with the relatively recent higher than that in the human population, and a larg- domestication of this breed. Most cats affected with er proportion of canine relatives are affected than OCD had self-mutilation or excessive grooming. No appears true for humans. This strongly suggests a cats were reported to have signs of hallucinating; how- ever, hallucinations may have been associated with tail Results of recent studies indicate that OCD in chasing. Most owners of these cats reported that the humans is the result of dysfunction of genes involving cats acted as if something was on or near the cat’s tail neurochemical and intracellular regulatory systems.26,27 and that the cat was either trying to chase this entity or Similar complex regulatory systems that have a genet- escape it. Accordingly, feline hallucinations may not ic, heritable basis have also been reported for dogs28 have been adequately identified in this study.
Unlike cats, few dogs had OCD after trauma or Human OCD has been postulated to be caused by social-situational distress or upheaval, and few had aberrant serotonin metabolism.30-32 Accordingly, treat- concurrent behavioral diagnoses involving elimination ment has been directed at affecting serotonergic metabo- or social relationships with other dogs. These data sug- lism; pharmacological agents used for treatment are fair- gest that the behavioral characteristics, neuroanatomic ly specific and affect subclasses—primarily the 5-HT1A regions affected, and molecular and neurogenetic class—of serotonin receptors. Neuropharmacologic mechanisms of OCD may differ for dogs and cats. Two approaches to treatment have sought to address such reg- dogs had OCD after physical trauma. In both dogs, the ulatory abnormalities by augmenting serotonin through trauma consisted of abusive training (hanging by a the use of TCAs and SSRIs.33-39 The key to the success of choke collar). That 2% of this population of dogs with the specific TCAs and SSRIs over other classes of med- OCD was subject to such abuse should be of concern ication is that they use the same second messenger sys- tems and transcription pathways that are used to develop One pet-store dog had profound coprophagia, sug- gesting that at some point coprophagia may have rep- While the best design for comparing drug efficacy resented a nutritional strategy. Of the 103 dogs, few is a prospective, placebo-controlled, double-blind (approx 10%) had a putative neurologic disorder, study, other statistical comparisons can be made if cri- physical condition, or potentially painful disorder teria for switching medications are consistent, as was associated with OCD, which could either be primary or the case here. Such techniques are underused in veteri- secondary to OCD. One dog had a diagnosis of irrita- nary medicine, which is unfortunate since the funding ble bowel syndrome, a diagnosis that may be simply a and large enrollment pools required for the former are 1450 Scientific Reports: Retrospective Study JAVMA, Vol 221, No. 10, November 15, 2002 seldom available. As is true for humans, dogs with dogs, clomipramine reaches steady-state concentra- OCD respond well to the TCA, clomipramine,7,11,18,25 tions in 3 to 5 days, peak plasma concentrations are and to the SSRI, fluoxetine.42-46 Results of the study attained in approximately 1 to 3 hours, the half-life of reported here indicated that clomipramine was superi- the parent compound is 1 to 16 hours, and the half- or for treatment of OCD in dogs, compared with life of the active intermediate metabolites is 1 to 2 amitriptyline. The difference in efficacy is likely asso- hours.52,53 These data suggest that dogs may require ciated with specificity for the serotonin 1A subtype (5- higher dosages or more frequent dosing than do HT1A) receptor of the parent compound and at least 1 humans treated with such medications. Should the of the intermediate metabolites that acts as a SSRI.35,40 medication be discontinued, relapses occur in many This specificity may also be responsible for the success cases.8,13 Signs also worsened or became more pro- of fluoxetine in the treatment of some forms of nounced in stressful or anxiety-inducing circum- OCD,47,48 although our sample size was not sufficient to stances for some patients in our study. Use of clomipramine to treat OCD in animals is extralabel Adverse effects appear rare in canine patients; the most common adverse effects have been gastrointesti-nal disorders.11,49 Use of TCAs is contraindicated in ani- aAvailable from corresponding author upon request.
b mals with a history of urinary retention and severe, Clomicalm, Novartis Animal Health, Greensboro, NC.
dAmitriptyline, Stuart, Wilmington, Del.
It is surprising that amitriptyline was at all effica- eClomipramine, Ciba-Geigy, Summit, NJ.
cious (32/54 animals) in the treatment of OCD in our fFluoxetine, Eli Lilly & Co, Indianapolis, Ind.
study. Although not the drug of choice for treatment of gBuspirone, Mead Johnson Pharmaceuticals, division of Bristol- OCD in humans, this relatively nonspecific TCA may sufficiently decrease nonspecific anxiety so that iHydroxyzine, Roering, New York, NY.
patients can learn to change their behavior. At present, we have no way to evaluate how advanced OCD is kSertraline, Pfizer Animal Health, Groton, Conn.
when it is diagnosed in dogs and cats. Early signs may go unnoticed. The success associated with treatment with amitriptyline may reflect that some animals haveless severe forms of OCD and fewer comorbid diag- References
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