Agneta Egenvall

Breed Risk of Pyometra in Insured Dogs in Sweden

An animal insurance database containing data on over 200,000 dogs was used to study the occurrence of pyometra with respect to breed and age during 1995 and 1996 in Swedish bitches <10 years of age. A total of 1,803 females in 1995 and 1,754 females in 1996 had claims submitted because of pyometra. Thirty breeds with at least 800 bitches insured each year were studied using univariate and multivariate methods. The crude 12-month risk of pyometra for females <10 years of age was 2.0% (95% confidence interval = 1.9-2.1%) in 1995 and 1.9% (1.8-2.0%) in 1996. The occurrence of pyometra differed with age, breed, and geographic location. The risk of developing pyometra was increased (identified using multivariate models) in rough Collies, Rottweilers, Cavalier King Charles Spaniels, Golden Retrievers, Bernese Mountain Dogs, and English Cocker Spaniels compared with baseline (all other breeds, including mixed breed dogs). Breeds with a low risk of developing the disease were Drevers, German Shepherd Dogs, Miniature Dachshunds, Dachshunds (normal size), and Swedish Hounds. Survival rates indicate that on average 23-24% of the bitches in the databases will have experienced pyometra by 10 years of age. In the studied breeds, this proportion ranged between 10 and 54%. Pyometra is a clinically relevant problem in intact bitches, and differences related to breed and age should be taken into account in studies of this disease.

Mortality in over 350,000 Insured Swedish dogs from 1995–2000: I. Breed-, Gender-, Age- and Cause-specific Rates

This study presents data on over 350,000 insured Swedish dogs up to 10 years of age contributing to over one million dog-years at risk (DYAR) during 1995–2000. A total of 43,172 dogs died or were euthanised and of these 72% had a claim with a diagnosis for the cause of death. The overall total mortality was 393 deaths per 10,000 DYAR. Mortality rates are calculated for the 10 most common breeds, 10 breeds with high mortality and a group including all other breeds, crudely and for general causes of death. Proportional mortality is presented for several classifications. Five general causes accounted for 62% of the deaths with a diagnosis (i.e. tumour (18%), trauma (17%), locomotor (13%), heart (8%) and neurological (6%)). Mortality rates for the five most common diagnoses within the general causes of death are presented. These detailed statistics on mortality can be used in breed-specific strategies as well as for general health promotion programs. Further details on survival and relative risk by breed and age are presented in the companion paper [14].SammanfattningMortalitet hos hund baserad på data från över 350 000 svenska hundar försäkrade under 1995 till 2000: 1. Ras-, ålders-, köns- och orsaksspecifika rater.I denna studie presenteras data från över 350 000 försäkrade svenska hundar, med en ålder upp till 10 år, som tillsammans har bidragit med över en miljon hundår av risk (HÅR) under åren 1995 till 2000. Totalt dog eller avlivades 43 172 hundar. Av dessa hade 72% fått en dödsorsaksdiagnos. Den totala mortaliteten var 393 dödsfall per 10 000 HÅR. Mortalitet ututräknades generellt och per dödsorsak för de 10 vanligaste hundraserna, för 10 hundraser med hög mortalitet och för en övrig grupp. Flera typer av proportionell mortalitet presenteras. Fem generella orsaker stod för 62% av alla dödsfall där diagnos förelåg – tumörer (18%), trauma (17%), problem från rörelseapparaten (13%), hjärta (8%) och neurologiska problem (6%). Mortaliteten för de fem vanligaste diagnoserna inom de generella dödsorsakerna presenteras. Denna detaljerade mortalitetsstatistik kan användas både för rasspecifika strategier och för mer generella hälsobefrämjande åtgärder.

Detection of granulocytic Ehrlichia species DNA by PCR in persistently infected dogs.

Three female beagle dogs inoculated with granulocytic Ehrlichia species were monitored for four to six months to determine whether there was evidence that the organisms persisted. The dogs were inoculated intravenously with blood containing an Ehrlichia species closely related to Ehrlichia equi and Ehrdichia phagocytophila, and identical to the human granulocytic ehrlichiosis agent with respect to its 16S rRNA gene sequence. The clinical signs were evaluated, and blood samples were collected for haematology, serum biochemistry and serology. Ehrlichial inclusions in the blood were monitored by microscopy, and ehrlichial DNA was detected by the polymerase chain reaction (PcR). Two of the dogs were injected with prednisolone on days 54 to 56 and days 152 to 154 after infection, and the other was injected with prednisolone on days 95 to 97 after infection. The dogs were euthanased and examined postmortem. Ehrlichial inclusions were demonstrated in the neutrophils and seroconversion occurred shortly after inoculation. Two of the dogs developed acute disease with rectal temperatures above 39.°C, after which no further clinical signs were observed. The administration of corticosteroids seemed to facilitate the detection of ehrlichial inclusions. Ehrlichial DNA was detected intermittently by PCR in blood samples from two of the dogs throughout the study. Persistent infection was demonstrated up to five-and-a-half months after inoculation.

Clinical features and serology of 14 dogs affected by granulocytic ehrlichiosis in Sweden

The clinical features and the titres to Ehrlichia equi, E canis, E risticii, Rickettsia rickettsii and Borrelia afzelii in 14 Swedish dogs, in which ehrlichiosis was diagnosed on the basis of the presence of inclusions in granulocytes, are reported. Most of the dogs were moderately ill but made a rapid recovery after treatment with doxycycline. The dogs with inclusions were thrombocytopenic. Analysis of the antibody titres indicates that serology to E equi will remain the most appropriate serological test for granulocytic ehrlichiosis in Swedish dogs, until a specific test is developed for detecting the recently identified subspecies of Ehrlichia.

Mortality in insured Swedish dogs: rates and causes of death in various breeds

Data on over 222,000 Swedish dogs enrolled in life insurance in 1992 and 1993 were analysed. There were approximately 260 deaths per 10,000 dog-years at risk. Breed-specific mortality rates and causes of death are presented for breeds with more than 500 dogs at risk that had consistently high or low rates. Breed-specific mortality ranged from less than 1 per cent to more than 11 per cent. True rates and proportional statistics for the cause of death were calculated for the entire insured population (250 breeds) and cause-specific mortality rates were calculated for the breeds with the highest risk of dying of the most common causes. Trauma, tumours and problems related to the locomotor system together accounted for more than 40 per cent of all deaths or euthanasias. Although limited to insured dogs, these data cover approximately one-third of all Swedish dogs and provide baseline mortality data for further population-based studies on health and disease.

Validation of computerized Swedish dog and cat insurance data against veterinary practice records

Large computerized medical databases offer great potential for epidemiological research. However, data-quality issues must be addressed. This study evaluated the agreement between veterinary practice records and computerized insurance data in a large Swedish claims database. For the year 1995, the company insured over 320,000 dogs and cats. A total of 470 hard-copy records were sampled from claims for health care (n = 236) and life insurance (n = 234). Computerized insurance data for these claims were accessed and records from the attending veterinary practices were collected. For health and life claims, respectively, 79.2 and 72.8% of practice records were retrieved. Variables compared between the computer and practice records were breed, sex, date of birth and diagnosis for the claim. The degree of agreement was categorized as agreement, minor disagreement, major disagreement or data missing. Multivariable logistic regression was used to examine factors associated with errors. The observed agreement for breed and sex was excellent. There was 28.9 and 33.8% minor disagreement for the date of birth for health and life claims, respectively. This was mainly because, prior to 1993, the date of birth was coded as the first of January when more complete information was unavailable. Major disagreement (different year of birth) was low for both health and life claims. For health and life claims, the observed agreement for diagnosis was 84.0 and 84.9%, minor disagreement was 6.4 and 4.3%, and major disagreement 5.9 and 9.4%, respectively. Although there was no difference based on size of the veterinary clinic involved, there was a tendency for better agreement between the practice record and the computerized insurance data for claims from clinics with computerized practice records (n = 40) than for clinics with manual practice records (n = 286). Rates of discrepancy were affected by the clerk who processed the claims. Records processed by two of the 21 clerks had significantly more disagreements. Given the nature of the data, it was only possible to calculate a measure of observed agreement. In general, the agreement between data in the insurance-company database and from the practice records was excellent for demographic data such as breed and sex and fair for diagnostic information and date of birth. In general, the data are adequate to support ongoing research with due considerations of certain limitations.

Mortality in over 350,000 Insured Swedish Dogs from 1995–2000: II. Breed-Specific Age and Survival Patterns and Relative Risk for Causes of Death

This study continues analysis from a companion paper on over 350,000 insured Swedish dogs up to 10 years of age contributing to more than one million dog-years at risk during 1995–2000. The age patterns for total and diagnostic mortality and for general causes of death (trauma, tumour, locomotor, heart and neurological) are presented for numerous breeds. Survival estimates at five, eight and 10 years of age are calculated. Survival to 10 years of age was 75% or more in Labrador and golden retrievers, miniature and toy poodles and miniature dachshunds and lowest in Irish wolfhounds (91% dead by 10 years). Multivariable analysis was used to estimate the relative risk for general and more specific causes of death between breeds accounting for gender and age effects, including two-way interactions. Older females had tumour as a designated cause of death more often than males in most breeds, but not in the Bernese mountain dog. Information presented in this and the companion paper inform our understanding of the population level burden of disease, and support decision-making at the population and individual level about health promotion efforts and treatment and prognosis of disease events.SammanfattningMortalitet hos hund baserad på data från över 350 000 svenska hundar försäkrade under 1995 till 2000: II. Rasspecifika ålders och överlevnadsmönster och relativ risk för olika dödsorsaker.Detta är del 2 i en studie där data på över 350 000 försäkrade svenska hundar under 10 års ålder analyserats. Resultaten grundas på mer än en miljon hundår av risk under 1995 till 2000. Åldersmönstret för den totala och diagnostiska mortaliteten, och också för generella dödsorsaker (trauma, tumörer, problem från rörelseapparaten, hjärta och neurologiska problem) presenteras för ett flertal hundraser. Beräknad överlevnad vid 5, 8 och 10 års ålder presenteras. Överlevnaden vid 10 års ålder var 75% eller högre hos labrador och golden retriever, dvärg- och mellanpudel samt dvärgtaxar och lägst hos irländska varghundar (91% var döda vid 10 års ålder). Multivariabel analys användes för att beräkna relativ risk för generella och mer specifika dödsorsaker för olika raser, med hänsyn taget till könsoch ålderseffekter vilket också inkluderar två-vägs interaktioner. I de flesta hundraser hade äldre tikar tumör som dödsorsak oftare än äldre hanhundar, med undantag för berner sennen hundar. Information som presenteras i denna del (2) och del 1 ger insikt om dödsorsakspanoramat hos hund. Detta kan ge stöd för beslut på både populations och individuell nivå om vilka åtgärder somkan vidtas för att förbättra hundars hälsa, såväl behandlingsmässigt som prognostiskt.

Gender, age, breed and distribution of morbidity and mortality in insured dogs in Sweden during 1995 and 1996.

More than 200,000 dogs insured by one Swedish company at the beginning of either 1995 or 1996 were included in a retrospective, cross-sectional study. They could be covered for veterinary care at any age, but were eligible for life insurance only up to 10 years of age. Accessions for veterinary care that exceeded the deductible cost were used to calculate the risk of morbidity. The morbidity and mortality data have been stratified by gender, age, breed, location and human population density. In each year, 13 per cent of the dogs experienced at least one veterinary care event and the mortality risk was 3-0 per cent. The risk of morbidity varied with age, gender, breed, and location. The risk of mortality increased principally with age. It was possible to derive population-based risks of morbidity and mortality from these insurance data.

Early manifestations of granulocytic ehrlichiosis in dogs inoculated experimentally with a Swedish Ehrlichia species isolate

Seven beagles were inoculated experimentally with a Swedish canine Ehrlichia species isolate to study its pathogenicity. With respect to the 16S rRNA gene sequence, the isolate was identical to the human granulocytic ehrlichiosis (HGE) agent and closely related to both Ehrlichia equi and E phagocytophila. After an incubation period of four to 11 days, the most prominent clinical signs were high fever for two to five days and depression. AU the dogs developed profound thrombocytopenia, moderate leukopenia and a strong serological antibody response. Ehrlichial inclusions were detected in blood neutrophils from four to 14 days after inoculation for four to eight days. Ehrlichial DNA could be detected by polymerase chain reaction during the parasitaemic stage and a few days before and after microscopic inclusions were visible. Postmortem, the dogs showed reactive splenic hyperplasia and non-specific mononuclear reactive hepatitis.

Incidence of and risk factors for atopic dermatitis in a Swedish population of insured dogs

The incidence of atopic dermatitis was estimated to be 1·7 cases per 1000 dog-years at risk in a population of insured Swedish dogs whose insurance claims for the period 1995 to 2002 were examined. Several factors were found to increase the risk of having a recorded claim, including living in a city or in central or southern Sweden, being born in the autumn, and belonging to a high-risk breed. Bull terriers had the highest risk, with 21 cases per 1000 dog-years at risk, and several other breeds including boxers and West Highland white terriers also had an above average risk. There was no difference in the incidence between the sexes. There was a slight increase in the incidence during the period. In a subset of the data that consisted only of dogs from 15 high-risk breeds, the overall survival appeared to be lower for the dogs that had had an insurance claim for the disease.