Morbidity of insured Swedish cats during 1999–2006 by age, breed, sex, and diagnosis

Journal of Feline Medicine and Surgery (2010) 12, 948e959doi:10.1016/j.jfms.2010.08.008

Morbidity of insured Swedish cats during 1999e2006by age, breed, sex, and diagnosis

Agneta Egenvall DVM, PhD, Dipl EVCPH1,*, Brenda N Bonnett BSc, DVM, PhD

1,Jens Haggstrom DVM, PhD, Dipl ECVIM-CA (Cardiology)

1, Bodil Strom Holst DVM, PhD, Dipl ECAR1,

Lotta Moller DVM2, Ane Nødtvedt DVM, MSc, PhD

3

1Department of Clinical Sciences,Box 7054, Swedish University ofAgricultural Sciences, SLU, SE-75007 Uppsala, Sweden2Agria Insurance, P.O. Box 70306,SE-107 23 Stockholm, Sweden3Department of CompanionAnimals, Norwegian VeterinarySchool, P.O. Box 8146 Dep., 0033Oslo, Norway

*Corresponding author. Tel : þ[email protected]

1098-612X/10/120948+12 $36.00/0

The aim of the study was to describe patterns of morbidity, as reflected byreimbursed claims for veterinary care among cats covered by a Swedishinsurance company during 1999e2006. The annual incidence rates of having atleast one veterinary care event were calculated overall and stratified by sex, age,breed, diagnosis and urban/other location. The total rate was 875 (95% CI858e892) cats with claims per 10,000 cat-years at risk. The Siamese, Burmese,and the Abyssinians had high rates of claims, compared to the Norwegian Forestcat, the Maine Coon, the European Shorthair and domestic cats. The mostcommon causes for insurance claims were trauma, gastrointestinal and lowerurinary tract problems and there was substantial breed, sex and age variation forcertain problems. For example, among cats under 9 years of age, the rate forlower urinary tract problems was 2e3 times higher in males than females.

Date accepted: 20 August 2010 � 2010 Published by Elsevier Ltd on behalf of ISFM and AAFP.

It is useful to quantify the occurrence of the com-mon diseases in cats, both in general and for spe-cific subpopulations defined by sex, age and

breed. Information on feline disease frequency canbe utilized by veterinary practitioners to guide clinicaldecision making, by breeders or clubs when planningbreeding programmes and by owners when acquiringa new pet. Unfortunately, population-based studiesregarding disease occurrence in cats are scarce. Oneof the reasons few estimates of feline morbidity arepublished, is the lack of knowledge about the back-ground population at risk.

Data kept by pet-insurance companies can poten-tially be a useful source of information regardingdisease and death in the owned populations of catsand dogs.1 A benefit of using these existing data-bases is that the population at risk is known and es-timates of disease incidence can be calculated. Dueto the considerable size of the insurance databases,stratifications by sex, age, breed and more can beperformed and risk factors for disease or death canbe assessed. Data on an insured cat population inthe UK have been used to calculate the prevalenceof feline diabetes mellitus, as well as to investigate

-70-3799544. E-mail :

� 2010

breed differences in the odds of developing thedisease.2

The Swedish insurance database (Agria Insurance,PO 70306, SE-107 23, Stockholm, Sweden) has beenused extensively to describe the pattern of mortalityand morbidity in dogs and horses.3,4 Recently, thisdatabase was used to describe patterns of mortalityin life-insured cats under 13 years of age.5 However,life insurance is purchased almost exclusively forpure-bred cats in Sweden. Veterinary care insuranceis more widely subscribed than life insurance, and ac-cessing information on cats’ veterinary care coverageprovides estimates of disease frequency relevant tothe more general Swedish cat population. However,even if a substantial fraction of the Swedish cat pop-ulation is insured for veterinary care (around 20%;personal communication, I Ahlen) there are likely tobe some major differences between insured andnon-insured cat populations. The most obvious isthe likelihood that a cat will receive expensive veter-inary care.

The aim of the study was to describe the patternof morbidity in cats, as reflected by reimbursedclaims for veterinary care insurance in cats insuredat the Agria insurance company during the periodfrom 1999 to 2006. Findings are presented overalland stratified by sex, age, breed group, diagnosisand location.

Published by Elsevier Ltd on behalf of ISFM and AAFP.

mailto:[email protected]

http://dx.doi.org/10.1016/j.jfms.2010.08.008



949Morbidity of insured Swedish cats

Materials and methods

Description of the insurance process 1999e2006

In order to qualify for veterinary care insurance atAgria, a cat must be vaccinated against feline panleu-kopenia. Cats can enter a veterinary care-insuranceprogramme at any age and stay insured for theirwhole life. If a cat is older than 6 years when first in-sured, a health certificate from a veterinarian must ac-company the application. The insurance is renewedannually but can be terminated at any time if theowner so desires.

There is a set deductible amount (in the year 2003 itwas 1200 Swedish Kronor (SEK) (when 100 SEKw$80US)) for a claim period (ie, 100 days), while the me-dian premium was 450 SEK and for the majority ofcats the maximum for which animal owners couldbe reimbursed within a year was 30,000 SEK, duringthe period. After a veterinary visit presumed to becovered by insurance, the receipt for veterinary carecosts is submitted to the insurance company, eitherelectronically or by mail. Veterinarians classify themedical problems using a standardised diagnosticregistry, including both specific and general codes.6

In general, only one diagnostic code is used per claim.

Data management

Data on all cats insured between 1999 and 2006 weredownloaded from the Agria insurance database. Vari-ables used in this study included cat identification,sex, date of birth, breed, veterinary care-insurancecoverage, postal code of the owner and diagnosticcode(s). Dates of visits to veterinarians, when cats en-tered or left the insurance programme and reasons forleaving insurance were also included. Cats were as-signed to the age category they had 1 January eachyear (0< 1 years, 1< 2, etc.).

Sex was either male or female as recording and tim-ing of neutering were not reliable in the database. Inthe insurance data, 41 breed codes were used. Breedsthat were considered closely related were combinedfor analysis; ie, Abyssinians and Somalis were com-bined to Abyssinians; Persians, Chinchilla, colour-point Persians and Exotic Shorthairs to the Persiangroup; and Siamese, Balinese, Foreign White, Java-nese, Oriental Shorthair and Seychellios to the Sia-mese group. ‘Domestic’ cats included domesticShorthair and Longhair cats. The ‘other’ group(a specific code at Agria) included various breeds.

Diagnoses were amalgamated into broad diagnosticcategories/problems/locations: allergy, behaviour,blood/lymphatic vessels, blood disorders (includinghaematology, serum biochemical alterations and elec-trolyte disturbances), blood producing organs, cardio-vascular, claw, otological, endocrine, gastrointestinal,immunological, infection, integumentary, locomotorproblems, liver/pancreatic diseases, oral, neoplasia,neurological, surgery/complications thereof, peri-

parturent problems, ocular, procedural complications,reproduction in females and males respectively, lowerand upper respiratory tract, unspecific signs of dis-ease (symptomatic) (eg, fever, pain, unspecified), den-tal, thoracic, trauma, lower and upper urinary tractand whole body. Diagnoses were also presented ona specific ‘diagnostic code’ level (somewhat amalgam-ated from original diagnoses). A complete list of diag-noses is available from the first author.

Data analysis

Descriptive statistics were calculated. Cats were atrisk from either the 1 January 1999, or the start dateof insurance (if later) until the date of death or with-drawal from insurance.

Cats with one or more reimbursed receipts for vet-erinary care (ie, at least one veterinary care event(VCE)) submitted to the insurance company withina year contributed to the numerator for morbidity. In-cidence rate (IR) calculations were performed with theexact time at risk (cat-years at risk (CYAR)) as the de-nominator. Rates are expressed as deaths per 10,000CYAR. Standard errors times 1.96 yielded 95% confi-dence intervals (95% CIs) for IRs. In general non-over-lapping 95% CIs have been used as evidence ofstatistical difference, mainly comparing rates withinthe respective categories for sex, age, breed group, di-agnosis and location.

Rates were calculated crudely, by year, sex, breedgroup, breed, urban/other location, diagnostic cate-gory, diagnosis, and by combinations thereof as wellas for withdrawal (for any reason, including death).Data are presented for individual breeds with at least500 CYAR over the whole period and for diagnosticcategories and diagnoses with an annual average ofat least 100 and 20 VCEs, respectively. All rates werecalculated annually and in most cases averaged there-after. For overall rates the oldest age group includedcats �16 years of age, whereas by diagnostic categoryit was �13.

Proportional morbidities by diagnostic categorywere calculated including cats with at least one VCE(irrespective of reason) in the denominator and catswith a specific claim for the category in the numerator.For specific diagnoses, the denominator was the totalnumber of cats in the relevant diagnostic category. Ac-cordingly, summing the proportions will add to over100%, because some cats will have several diagnoses,or diagnoses within several categories, within a year.Data handling was performed by SAS version 9.1(SAS Institute Inc, Cary, NC 27513, US).

Results

The population

The total number of cats was 301,485 and the totalnumber of CYAR 1,013,012. The number of CYAR

950 A Egenvall et al

varied from a low of 86,531 in 1999 to a high of 179,642in 2006. The 10th, 50th and 90th percentiles for num-ber of years of insurance per cat during the wholetime period were 0.5, 3.0 and 10.6 years. Most cats(76%) entered insurance before 2 years of age.

The mean and median ages of the insured cats were4.2 and 3.5 years and varied little over the time period(data not shown). The proportion ofmale catswas 53%.Fig 1 shows the distribution of CYAR by age category.The breed distribution is found in Table 1. The aver-aged annual overall withdrawal rate was 975 (95% CI958e993) cats per 10,000 CYAR. The total number ofcats with claimed receipts was 62,456, varying between6999 (year 1999) and 14,317 (year 2006). Averaged, the10th, 50th and 90th percentiles of number of receiptsper cat and year were 1, 1 and 3.6.

Overall morbidity

Overall (1999e2006) the averaged annual rate of atleast one VCE was 875 (95% CI 858e892) cats per10,000 CYAR. This approximates to 8.4% of cats hav-ing at least one VCE annually (1� e(�IR)). The highestrate was for year 2001 and the lowest for 2006; 932(95% CI 913e951) and 826 (95% CI 813e840) catswith �1 VCE per 10,000 CYAR, respectively.

The overall averaged rate for males was 967 (95%943e992) and for females it was significantly lowerat 769 (95% CI 745e792) cats per 10,000 CYAR. Byage the rate was 1000 cats per 10,000 CYAR at the low-est age, 650 per 10,000 CYAR at age categories 3< 5and then 2000 cats per 10,000 CYAR at 14< 15 yearsof age (Fig 1). By age category, females had a signifi-cantly lower rate in age categories 1< 2 to 7< 8, com-pared to males (data not shown). Breed-specific ratesare found in Table 1, where, for example, the breedgroup Siamese has a significantly higher IR than theNorwegian Forest cat and the domestic cats. In urbanareas, the rate was 1002 (95% CI 976e1030) and inother areas 775 (95% CI 753e796) cats with �1 VCEper 10,000 CYAR, the difference between areas beingsignificant.

0

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Fig 1. Number of CYAR and rate for at least one VCE per aduring 1999e2006 at a Swedish insurance company (annual av

Cause-specific morbidity

The most common diagnostic categories are presentedin Table 2. Among cats with claims, 20% had at leastone claim within the category trauma and 14% withingastrointestinal. Table 3 shows the specific codes(somewhat amalgamated from the original diagnoses)within diagnostic categories, for conditions affecting,on average, at least 20 cats per year. Among catsthat had a claim for trauma, 50% had at least oneclaim for a bite/cut/wound. Among cats with a claimunder urinary, lower, 44% had at least one claim forcystitis and 38% had at least one claim for an unspec-ified urolith.

The graphs by diagnostic category, sex and age(Fig 2) suggest a sex difference for trauma, especiallyat low ages (males higher), but larger differences forlower urinary problems (males higher). For neoplasia,females have a much higher rate at older ages thanmales (Fig 2), with mammary tumour being themost common specific type, followed by skin tumours(data not shown). Compared to cats between 1 and 5years of age, claims due to ocular disease were (ingeneral significantly) more common for cats youngerthan 1 year, whereas at older ages the 95% CIs over-lap. Fig 3 contrasts the rates by breed group and diag-nostic category. For example, the Persian group hasa low rate of traumatic problems, but a high rate of oc-ular problems. Further, the IR of claims for lower uri-nary tract disease (LUTD) was significantly increasedamong the Persian group and Norwegian Forest catsand decreased for the Siamese group as compared todomestic cats.

Discussion

Overall, sex, age, breed and urban/other location

In general, the insured population increased in sizewhile the annual age distributions and morbidityrates remained relatively stable over the years

9 < 1 0

1 1 1 < 0 1

2 1 < 1 3 1 < 2 1 1

4 1 < 3 5 1 < 4 1 1

6 1 < 5 6 1 = >

egory

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AR idence rate

ge category. Data are from cats insured for veterinary careerage 126,627 CYAR).

Table 1. Total CYAR, and annual average values for number of cats with at least one VCE and (rankedby) IRs per 10,000 CYAR (with 95% CI) for breeds/breed groups with at least 500 CYAR for cats insuredfor veterinary care during 1999e2006 at a Swedish insurance company.

Breed/breed group Total CYAR Annual average numberof cats with �1 VCE

Annual average IR 95% CI

Korat 544 11 1616 670 2563Rex 796 14 1385 653 2116Siamese group 13,621 234 1377 1200 1554Burmese 9039 151 1339 1126 1553Abyssinian group 7774 128 1333 1099 1566Bengal 1934 26 1283 598 1969Other breeds 7693 107 1171 931 1410Persian group 67,970 953 1121 1049 1192Ocicat 2143 30 1120 684 1556British Shorthair 11,070 152 1113 931 1294Russian Blue 4432 57 1031 764 1298Birman 40,853 515 1010 922 1098Devon Rex 4424 55 1001 726 1275Ragdoll 6965 82 975 725 1224Cornish Rex 6147 75 961 731 1190Norwegian Forest cat 37,287 438 940 851 1029Maine Coon 9464 107 875 695 1055European Shorthair 45,122 478 848 772 924Domestic cat 693,558 6945 804 785 824Turkish Van 830 7 713 211 1215Manx 598 5 639 68 1210


analysed. Over 8% of cats having at least one reim-bursed insurance claim each year is a substantial pro-portion of the population, albeit less than that seen indogs and horses (13 and 11%, respectively).3,4

Females had a lower morbidity rate, compared tomales and significantly lower IRs than males at lowages. In dogs, females had a higher rate from age cat-egory 6< 7 to 11< 12, but at younger ages the rateswere similar for males and females, overall, althoughthis varied by breed (unpublished observations).3 Al-though free-roaming intact male cats would be un-common among Swedish insured cats, the highermorbidity rates in male cats could be a function ofboth anatomical predisposition (eg, urinary tract dis-ease), and behavioural differences (eg, wounds,trauma) also in neutered male cats.

Some breeds, ie, the Siamese group, the Burmeseand the Abyssinians had high rates of morbidity, com-pared to eg, the Norwegian Forest cat, the MaineCoon, the European Shorthair and domestic cats(based on non-overlapping CIs). Differences may re-late to genetic predisposition, ie, reflecting true breeddifferences in disease load. Several breed-related dis-eases have been reported for cats.7 However, such dif-ferences might also reflect conformational differences,whether cats of certain breeds are more likely to bekept indoors or allowed outdoors, or other reasons,such as owner attitudes. Marked breed differences intype and occurrence of disease in dogs are often not

related to genetic disease, but due to differences inconformation and use. As breed statistics are exam-ined, it is crucial to remember the complex aetiologyof many diseases.

The rate of at least one VCE was apparently higherin urban compared to other areas (based on this cur-sory analysis). Whether this is due to true differencesin disease risk, variation in breed distribution orowners’ attitudes, especially relative to outdoor/in-door cats, or a function of the availability and costof veterinary services is beyond the scope of this pre-liminary analysis, but may warrant further study.

Specific diagnoses

The top six specific diagnoses for feline morbidity inthis insured population are discussed below (exclud-ing ‘Unspecific signs of disease’, ranked fourth). Trau-matic injury (ranked first) was the singlemost commondiagnostic category, occurring in 20% of the cats withclaims. The specific traumatic reasons (Table 3) includecauses related to both animate and inanimate environ-mental dangers, and are likely a reflection of cats inter-acting with their surroundings. Most major traumasobviously occur outdoors, but owners may feel therisk is acceptable, in order to allow the cat to liveamore natural life than being confined, more safely, in-doors. Indoor cats are likely at higher risk of variousother diseases, perhaps related to lack of physical

Table 2. Annual average values (1999e2006) for number of cats with at least one VCE, IR (and 95% CI),of any VCEs per 10,000 CYAR, and proportional morbidity for diagnostic categories with at least 100VCEs per year (annual average 126,627 CYAR).

Diagnostic category Annual averagenumber of cats with

�1 VCE

IR per 10,000 CYAR Proportional morbidity

Rate 95% CI %*

Trauma 2170 174 167 182 20Gastrointestinal 1520 123 116 129 14Urinary lower 1365 109 103 115 13Unspecific signs of disease(symptomatic)

1292 102 96 108 12

Integumentary 946 75 70 79 9Neoplasia 707 58 54 62 7Urinary upper 523 41 37 45 5Ocular 500 40 37 44 5Infection 398 33 30 36 4Locomotor problems 356 27 24 30 3Respiratory upper 289 23 21 26 3Endocrine 269 20 18 23 3Liver, pancreas 260 21 18 23 2Respiratory lower 252 20 18 23 2Reproduction females 229 19 17 22 2Peri-parturent problems 205 17 15 19 2Cardiovascular 197 15 13 18 2Neurological 180 14 12 16 2Dental 169 13 11 16 2Oral 140 11 10 13 1Otological 136 11 9 13 1

*Percent of cats within a specific category, divided by all cats with claims.


activity and behaviour-related problems. In general,trauma was significantly more common in male catsthan females up to 5< 6 years of age. Road traffic acci-dents have been shown to bemore common inmales inthe UK and US.8,9 Note that no trauma diagnoses wereranked in the top 25-list in a study of medical recordsfrom primary care centres for companion animals inthe US by Lund et al10

The top causes in the gastrointestinal category (sec-ond) were similar to those from the US where 4% ofthe diagnoses were unspecific problems such as‘vomiting’ and ‘diarrhea’.10 This might reflect thatan etiological diagnosis is often not pursued or con-sidered possible and that cats most often recover with-out a more precise diagnosis.

In the mortality study,5 urinary disease (rankedthird, upper and lower) was dominated by diagnosespertaining to the kidney/ureter. However, lower uri-nary diagnoses were predominant in this study witha proportional morbidity of 13% as compared to 5%for upper. Risk factors for feline LUTD have beenstudied with a case-control approach using the Pur-due Veterinary Medical DataBase (VMDB), which in-cludes medical records from a variable number ofveterinary teaching hospitals in North America.11 Per-sians, Himalayan and Manx cats were found to be at

increased risk of LUTD when compared to domesticshorthairs while Siamese had a lower risk. A similarpattern was observed in this study for Persians, do-mestic cats and Siamese.

Integumentary problems were found to be the fifthmost common cause of morbidity, found in 9% of catswith claims. The majority of skin diagnoses probablystem from traumatic events (eg, ‘skin abscess/fis-tula’). The study by Lund et al10 shows a similar pro-portion for unspecific ‘skin disease’ to the currentstudy if one combines numbers for ‘feline miliary der-matitis’ and ‘dermatitis’ to a proportion of 4%.10 In thecurrent study, adding the proportions of such unspe-cific dermatological problems as ‘dermatitis (unspeci-fied)’, ‘pruritus’, ‘skin without further specification’,‘eosinophilic dermatitis’, ‘pyoderma’ and ‘alopecia’,accounts for 42% of all cats with integumentary prob-lems (equating to 3.8% of cats with claims).

Neoplasia was the sixth most common generalcause of morbidity in this study, with mammary neo-plasia, the most common specific type of neoplasia. Inan older study from the USA, mammary tumourswere the third most frequently diagnosed neoplasmin the cat.12 Cats belonging to the Siamese grouphad a high incidence of morbidity from neoplasiaand neoplasias, dominated by mammary tumours,

Table 3. Averaged IR of any VCE per 10,000 CYAR (annual average 126,627 CYAR) and proportionalmorbidity by diagnosis, with an averaged total of at least 20 diagnostic events/at least one VCE per year,with a specific code.

Diagnosticcategory

Diagnostic code Average numberof cats

with �1 VCE

IR per 10,000CYAR

Proportionalmorbidity

Rate 95% CI %*

Trauma Bite/cut/wound 1091 87 82 93 50Foreign body stomach/intestines 110 9 7 11 5Hit by car/train/vehicle 104 8 7 10 5Bites/snake/insect 81 6 5 8 4Foreign body mouth/throat 67 5 4 7 3Trauma claw 61 5 3 6 3Fall (eg, from apartment) 59 5 3 6 3Femoral fracture 52 4 3 5 2Cruciate rupture 42 3 2 4 2Pelvic fracture 39 3 2 4 2Hip joint sprain/strain etc 37 3 2 4 2Tibial/fibular fracture 36 3 2 4 2Trauma without further specification 32 2 2 3 1Mandibular fracture 27 2 1 3 1Radial/ulnar fracture 27 2 1 3 1Poisoning without further specification 24 2 1 3 1Foreign body (upper respiratory) 23 2 1 3 1Mouth/throat bite/cut/wound 23 2 1 3 1Trauma/skeletal without further

specification22 2 1 2 1

Carpal/metacarpal fracture 21 2 1 2 1Hock joint sprain/strain, etc 20 2 1 2 1

Gastrointestinal Vomiting 669 53 49 57 44Infection/inflammation(stomach/intestines)

329 28 25 31 22

Constipation/impaction 224 18 16 20 15Diarrhoea 164 13 11 15 11Vomiting/diarrhoea 92 7 6 9 6Stomach/intestines (unspecified) 37 3 2 4 2

Urinary lower Cystitis 601 48 44 52 44Urinary stone (unspecified) 518 42 38 45 38Urinary urgency 136 10 8 12 10Haematuria 80 6 5 7 6Urethral plug 50 4 3 5 4Lower urinary (unspecified) 49 4 3 5 4Magnesiumeammoniumephosphate

stones49 4 3 5 4

Voiding difficulties 22 2 1 3 2Urinary calculi (unspecified) 21 2 1 2 2

Unspecific signsof disease(symptomatic)

Anorexia 390 30 27 33 32Fever 201 16 14 18 17Signs without further specification 192 15 13 17 15Sick 173 15 12 17 14Emaciation 123 9 8 11 10Polyuria/polydipsia 94 7 5 8 8Fatigue 77 6 5 8 6Pain 34 3 2 4 3Dehydration 25 2 1 3 2

(continued on next page)


Table 3 (continued)

Diagnosticcategory


with �1 VCE

IR per 10,000CYAR


Rate 95% CI %*

Integumentary Skin abscess/fistula 428 33 30 36 45Dermatitis (unspecified) 140 11 9 13 15Anal sac inflammation/infection 106 9 7 10 11Pruritus 86 7 5 8 9Skin without further specification 62 5 4 6 7Eosinophilic dermatitis 43 3 2 5 4Pyoderma 34 3 2 3 4Alopecia 32 3 2 3 3

Neoplasia Mammary tumour 282 23 21 26 40Tumour skin 200 16 14 19 28Tumour stomach/intestines 41 3 2 4 6Tumour mouth/throat 26 2 1 3 4Neoplasia e without further


Urinary/upper Urinary/upper without furtherspecification

231 18 15 20 44

Uraemia 127 11 9 12 24Nephritis 102 8 6 9 19Erythropoietin deficiency anaemia

(renal failure)36 3 2 3 7

Nephrosis 23 2 1 3 4Ocular Conjunctivitis 123 10 8 12 25

Keratitis 71 6 4 7 14Corneal ulcer 57 4 3 6 11Uveitis 46 4 3 5 9Ulcer eye 44 4 2 5 9Ocular without further specification 31 3 2 3 6Cornea (other than ulcer) 29 2 2 3 6

Infection Infection (unspecified) 200 16 14 18 50Feline infectious peritonitis 35 3 2 4 9Virus (unspecified) 35 3 2 4 9Cat flu 32 3 2 4 8Scabies 29 2 1 3 7

Locomotor problems Lame without further specification 200 15 13 18 56Patellar luxation 21 2 1 2 6

Respiratory/upper Rhinitis/sinusitis 94 8 6 9 32Respiratory/upper without further


Cough 48 4 3 5 16Dyspnoea 37 3 2 4 13Acute tonsillitis 29 2 1 3 10

Endocrine Diabetes mellitus 153 12 10 14 57Hyperthyrosis 89 6 5 8 33Hypothyrosis 21 2 1 2 8

Liver, pancreas Liver (unspecified) 104 9 7 10 40Hepatitis 44 4 3 5 17Abnormal liver enzymes 34 2 2 3 13Icterus 24 2 1 3 9


Table 3 (continued )

Diagnosticcategory


with �1 VCE

IR per 10,000CYAR


Rate 95% CI %*

Respiratory lower Respiratory/lower (unspecified) 55 4 3 5 22Bronchitis ‘asthma’ 48 4 3 5 19Respiratory/lower inflammation/

infection39 3 2 4 16

Pneumonia 38 3 2 4 15Bronchitis 35 3 2 4 14

Reproduction female Pyometra/endometritis 169 14 12 16 74Peri-parturient Caesarean section 127 11 9 12 62problems Complication of delivery/dystocia 67 5 4 7 33Cardiovascular Cardiomyopathy 111 9 7 10 57

Heart (unspecified) 33 3 2 4 17Murmur 28 2 1 3 14

Neurological Neurological without furtherspecification

90 7 5 8 50

Epilepsy 32 3 2 4 18Dental Broken tooth 87 7 5 8 51

Calculus of teeth 31 2 2 3 18Teeth infection/inflammation 30 2 2 3 18Enamel defects 22 2 1 3 13

Oral Gingivitis/stomatitis 76 6 5 8 54Otological External otitis 101 8 7 10 74

*Percent of cats with a specific diagnosis, divided by all cats with claims within the relevant diagnostic category.


were the most common cause of death in Siamese catsin our mortality study.5 Factors other than breed thathave been suggested to influence the prevalence ofmammary tumours include age, hormone treatmentand neuter status. If cats are spayed before age of 1year the risk of mammary carcinoma development issignificantly reduced.13 Regular administration ofprogestins was associated with mammary carcinomain one study.14 Skin tumours were also common neo-plasms, in accordance with previous studies.12,15

Claims due to ocular disease (seventh) were dom-inated by conjunctivitis. There are several infectiousagents in cats that cause conjunctivitis, mostly inyoung animals: feline herpesvirus 1, Chlamydophilafelis and Mycoplasma felis being the most com-mon.16,17 The youngest cats had a high incidenceof ocular disease. In a survey among Swedish catbreeders, one-third reported having had cats withconjunctivitis the previous year.18 In the latter study,Persians had a higher frequency of conjunctivitisthan expected. Persians had the highest proportionof claims for ocular disease in the present study.This fact suggests that factors such as conformationmay influence disease occurrence. Brachycephalia,especially of profound or severe degrees, has beenshown to be associated with an aberrant course ofthe nasolacrimal duct: the duct can be steeply ori-ented and even V-shaped leading to inefficientdrainage function.19,20

A comparison of causes of illness

The top five causes of feline morbidity in this insurancedatabase were trauma, gastrointestinal disease, LUTD,unspecific signs of disease (symptomatic) and integu-mentary problems whereas, in the study by Lund etal,10 dental calculus and gingivitis were the most com-mon diagnoses in cats at a prevalence of 24.2% and gin-givitis 13.1%, respectively.10 Other common diagnosesin the material from the US were flea infestation affect-ing 9.2%andOtodectes species infestation affecting 7.4%of the cats. Dental disease was also the most commondisease reported in a UK survey of feline health (6% ofcats affected), followed by trauma (3.7%) and then up-per respiratory tract infection, LUTD and flea allergydermatitis (all 3.3%).21 When comparing the data fromdifferent sources, it should be noted that the veterinarycare insurance does not cover elective dental work andthat low-cost diagnoses are under-represented in the in-surance database. Also, flea infestation is likely lesscommon in Sweden, compared to warmer countries.Abscesses and cat bites also ranked high in the studyby Lund et al,10 with prevalences of 6.5 and 4.7%, re-spectively. In the current study, bite/cut/wounds ac-counted for half of the morbidity in the category‘trauma’ and abscess/fistula 45% of the diagnoses in‘integumentary’. Seen together, the impression is cer-tainly that cat-inflicted trauma is a very common causeof morbidity among cats in both Sweden and the US.

Trauma

0

200

400

600

800

Age categories

femalesmales

Gastrointestinal

0

100

200

300

400

500

Age categories

femalesmales

Lower urinary

0

100

200

300

400

500

Age categories

femalesmales

Integumentary

0

50

100

150

200

250

Age categories

femalesmales

Neoplasia

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200

400

600

800

0<1 1<2 2<3 3<4 4<5 5<6 6<7 7<8 8<9 9<10 10<11 11<12 12<13 >=13

0<1 1<2 2<3 3<4 4<5 5<6 6<7 7<8 8<9 9<10 10<11 11<12 12<13 >=13

0<1 1<2 2<3 3<4 4<5 5<6 6<7 7<8 8<9 9<10 10<11 11<12 12<13 >=13

0<1 1<2 2<3 3<4 4<5 5<6 6<7 7<8 8<9 9<10 10<11 11<12 12<13 >=130<1 1<2 2<3 3<4 4<5 5<6 6<7 7<8 8<9 9<10 10<11 11<12 12<13 >=13

0<1 1<2 2<3 3<4 4<5 5<6 6<7 7<8 8<9 9<10 10<11 11<12 12<13 >=13 0<1 1<2 2<3 3<4 4<5 5<6 6<7 7<8 8<9 9<10 10<11 11<12 12<13 >=13

Age categories

femalesmales

Upper urinary

0

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Fig 2. Age and sex-specific IRs, with alternatively upper and lower 95% confidence intervals, of at least one VCE by diag-nostic category of at least one VCE per 10,000 CYAR (annual average 126,627 CYAR) for seven most common systems(excluding ‘Unspecific signs of disease (symptomatic)’). Stars indicate where 95% confidence intervals do not overlap.


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r

Siamese group

Burmese Persian group

British Shorthair

Birman Norwegian Forest cat

Maine Coon European Shorthair

Domestic

IR

p

er 10,0000 C

YA

R

Fig 3. Breed and diagnostic category-specific IRs, for breeds with at least 8000 CYAR, and the seven most common diag-nostic categories (excluding ‘Unspecific signs of disease (symptomatic)’). GI¼ gastrointestinal.


A recent study of mortality in the same insured fe-line population reported that the most commoncauses of death by disease category for Swedish catswere urinary tract disease, trauma, neoplasia, infec-tions, cardiovascular and gastrointestinal diseases.5

In a survey carried out among cat-owners in the UK,the most common causes of death for cats were re-ported to be trauma, cancer and old age.22 Unlikefor the insured Swedish cats, a distinction betweendeath and euthanasia could be made and the mostcommon causes of death in the latter subset were can-cer, old age and kidney disease. It appears that whilecats visit the veterinarian because of injuries, vomitingand LUTD, they more commonly die from kidney dis-ease, neoplasia, infections and cardiovascular disease,as well as severe trauma. Some sudden deaths mayoccur without a preceding VCE (eg, undiagnosed car-diomyopathy). It is likely that some problems aremost often acute and/or quickly resolved, eg, catbites, whereas others, eg, upper urinary tract prob-lems may be chronic and/or recurrent during therest of the animal’s life. To fully appreciate these pat-terns longitudinal studies are needed with close mon-itoring of all types of illnesses and diseases.

Methodological considerations

This study is based on insured cats at one companyand it is estimated that 20% of the Swedish cat popu-lation is insured. There will likely be higher propor-tions of pedigree cats insured, even though domesticcats dominate the veterinary care data. So, pedigreecats in this study may be more typical of their overallpopulation than the insured domestic cats. The likeli-hood that insured cats receive veterinary care in case

of illness is likely to be higher than for uninsured,cared-for cats (there are relatively few stray cats inSweden). Presumably, uninsured cats may be morelikely to be euthanased, more quickly, than insuredcats for serious or chronic illness. Extrapolation of re-sults of this study to other cat populations must bedone with due consideration and caution. However,one could say that findings are in line with what wewould have expected, strengthening our conclusionsthat the findings are relevant. In general, Swedestend to insure their animals as a function of their com-mitment to responsible pet ownership, tradition andto limit financial burden, rather than an accurate per-ception of the risk inherent in the breed.

Diagnostic information for cats was previouslyvalidated. Similar to in the dog data we found thatdiagnostic information was correctly coded in 84%of scrutinised records and that data on breed, age(not date of birth, only year) and sex (only male/fe-male) was correctly coded to an even greater extent.23

Similar but not completely identical to the previouspublication on mortality in insured cats,5 we haveamalgamated diagnoses across systems and pro-cesses in the diagnostic registry.6 The reason forthis is to ease the interpretation of the data, becausesome similar diagnoses will otherwise be found indifferent categories (eg, unspecific lameness cannotbe attributed to a certain limb/body part). However,the challenge with diagnoses belonging to several di-agnostic groups still exists, eg, skin wounds are clas-sified as traumatic, rather than integumentary.Although there are potential downsides to the amal-gamation, based on our extensive experience withthe data and the diagnostic registry, we believe thatthe benefits are far greater.


These data are reflective of the causes recorded forclaimed cases of disease in these insured cats. As hasbeen seen in dog and horse data from this insurance da-tabase,many of the diagnoses are not refined, eg, simplycoded as ‘unspecified signs of disease’. Thismay be a re-sult of theway the companycollectsdiagnosticdata, vet-erinarians’ expertise or use of the diagnostic registryand/or, at least in some cases, it may accurately reflectthe level of work-up performed. Validation of a clinicalequine database has also shown some generalities andinconsistencies in the way diagnoses are recorded.24

To avoid over-counting events or receipts for veter-inary care, cats have been allowed to be included asa case only once in a year, crudely, by diagnostic cat-egory and by diagnosis. In other words, a cat mayonly have contributed to several diagnoses withina year if there were multiple receipts with different di-agnoses. Thus, values for ‘proportional morbidity’ re-flect the proportion of cats with at least one claim thathave a specific claim, as opposed to describing theproportion of claims.

Given the dynamic population over the years of thestudy, the age distribution for a breed could poten-tially influence the statistics. Some breeds, eg, the Rag-doll, have increased in popularity during the last fewyears and therefore could be younger, on average,than breeds with a more stable popularity, eg, the Si-amese. However, analysis of age-standardised ratesindicated little impact on the demonstrated patternsof disease (data not shown).

ConclusionThe Siamese group, the Burmese and the Abyssinianshad relatively high rates of VCEs, compared to theNorwegian Forest cat, the Maine Coon, the EuropeanShorthair and domestic cats. The most common med-ical problems were trauma, gastrointestinal and lowerurinary problems and there was substantial breed, sexand age variation. Cats located in urban areas hadhigher rates of veterinary care compared to cats inother areas. Whether these findings reflect true differ-ences in disease risk, variation in breed distribution orowners’ attitudes (including cats being indoor/out-door), or the availability and cost of veterinary ser-vices is beyond the scope of this study. This studyprovides comparative, quantitative estimates for dis-ease patterns in these insured Swedish cats, and, bear-ing in mind the limitations of the population and data,the findings can be extrapolated to increase our un-derstanding of health problems in cats.

Conflict of interestBrenda N Bonnett is presently an independent, part-time consultant to the Agria Insurance company.

AcknowledgementsThis study was supported by grants from the Founda-tion for Research, Agria Insurance.

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Morbidity of insured Swedish cats during 1999–2006 by age, breed, sex, and diagnosis

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