Heart Failure Is Common in Diabetic Cats: Findings from a Retrospective
Total Page:16
File Type:pdf, Size:1020Kb
Heart failure is common in diabetic cats: findings from a retrospective case-controlled study in first-opinion practice OBJECTIVES: To study the prognosis and cause of death in cats with Experimental induction of diabetes mel diabetes mellitus. litus in various laboratory mammals also causes cardiovascular disease and heart METHODS: Twenty consecutive cases of feline diabetes mellitus failure so that the prevalence of cardiac diagnosed in first-opinion practice were followed. Three control cats, disease and failure in diabetic cats seemed worthy of examination. The purpose of without diabetes, were matched to each case of diabetes; these this study was to examine the progno were also followed. sis and cause of death for a cohort of con secutive cases of feline diabetes mellitus RESULTS: One Somali cat with diabetes could not be matched, so diagnosed in a first opinion veterinary practice, and to compare these with con complete data analysis considered only 19 diabetics and 57 trol cats matched for age, breed and sex. matched controls. Death occurred in 14 of 20 diabetics and 23 of 57 controls although one control cat was eventually lost to follow-up. MATERIALS AND METHODS Heart disease and heart failure led to death in six diabetic cats. One of these was the non-matched Somali; nevertheless, the death rate Selection of cases The computer records of Barton Veteri from heart disease in the diabetics was five of 19 compared with two nary Hospital (BVH) were searched for of 57 in controls. The relative risk of heart failure in diabetic cats was all cases of feline diabetes first diagnosed during a six year period between June 10 4 times that of the controls; this difference in rates was 1999 and June 2005. Searching was statistically significant. Survival amongst diabetics was achieved by identifying all cats for which a fructosamine assay had been performed, significantly worse than for controls. For the control cats median and/or where insulin therapy, or oral survival was 718 days after the index visit, whereas for the diabetic hypoglycaemic medication, and/or a diet designed for use with feline diabetes had cases median survival was 385 days after diagnosis. been dispensed. These raw records were CLINICAL SIGNIFICANCE: Heart disease and failure are common in then reviewed in detail to identify cases, which were confirmed as diabetic based diabetic cats. This observation deserves further attention. on compatible clinical signs, concurrent hyperglycaemia and glycosuria, or concur rent elevated fructosamine levels, or both. INTRODUCTION These records were further sorted to iden tify those cases, which had been diagnosed Diabetes mellitus is common in the cat in the first opinion stream of the practice and the prevalence of this condition and treated under our care thereafter. appears to be increasing (Peterson 1998, Rand and Marshall 2004, Rand and others Selection of controls 2004). The prognosis for cats with diabe For each case of diabetes diagnosed tes mellitus in first opinion practice has according to these criteria, three matched received little attention in the literature; non diabetic control cats were sought by few data indicate why diabetic cats die. the following routine. The date of diagno Death in people with diabetes is over sis of each diabetic was identified together Barton Veterinary Hospital, 34 New Dover Road Canterbury, CT1 3BH Kent whelmingly because of cardiovascular dis with their breed, sex and age on that date. ease (Grundy and others 1999, Almdal The hospital database was searched for *Department of Statistics and Modelling Science, University of Strathclyde, Glasgow and others 2004, Bell 2004, Bertoni and matching control cats of the same age G1 1XD others 2004, Nichols and others 2004). (to the nearest year), breed and sex which had been seen at the hospital, either for as well as compatible clinical signs. The from the case control study for which only a routine vaccination or a new episode principal clinical signs recorded from 19 diabetic cats were thus eligible. of illness, within a maximum of 90 days these animals were: polydipsia/polyuria Control cats (n=57) consisted of 45 before or after the date of diagnosis of (80 per cent), weight loss (75 per cent), DSH and 12 DLH. The sex ratio of these the index diabetic case. If more than three polyphagia (65 per cent), depression/leth cats was identical to the diabetic cases (36 control cases were found, three control argy (25 per cent), capricious/variable males, 21 females) and again all were neu cases were chosen at random. appetite (15 per cent), dysuria/haematuria tered. Age structure of the control group (15 per cent) and peripheral neuropathy strongly resembled the age of the cases (10 per cent). Following routine haema (range five to 16 years, median 11Á5 years). RESULTS tology, biochemistry and urinalyses, other laboratory tests were frequently used in the Treatment and clinical outcomes Diabetic cats evaluation of these diabetic cats; those tests of the diabetic cases A total of 28 cats with a new diagnosis of used most frequently were: fructosamine At the time of writing, of these 20 diabetic diabetes were examined and treated at assays for diagnosis and/or monitoring cats, 14 were dead and six were still alive. BVH during the six year period in ques (in 75 per cent of cases), serial glucose The cause(s) to which death or euthanasia tion. Of these 28 cats, six were excluded curves (70 per cent of cases) and measure was ascribed are given in Table 1. Of the from further detailed analysis because ments of thyroid hormone (50 per cent of 14 cats that died, six were caused by heart their condition was originally diagnosed cases). Systemic arterial blood pressure was failure. Details of the clinical and labora elsewhere and the cats were referred to not measured in these cats. tory findings which confirmed the pres our second opinion service and/or their The 20 cats consisted of 15 domestic ence of heart failure in these cats are condition was managed at another prac shorthairs (DSH), four domestic longhairs given in Tables 2 and 3. tice subsequent to the cat being seen at (DLH) and one Somali cat. Males out One cat was euthanased, without treat our practice. Another two cats had both numbered females (13:7); all were neu ment, three days after diagnosis (case 15). diabetes and hyperthyroidism. These cases tered. Most cats were middle aged or Most of the cats that were treated eventu were also excluded from further analysis. older at the time of diagnosis (range six ally received insulin therapy (n=17) and The remaining 20 cats were the subject to 16 years). Median age at diagnosis was a diet particularly designed for diabe of this study. 12 years. tic cats (n=11) (Hills Feline W/D n=6, All cats diagnosed as diabetic exhibited We were unable to find any matching Hills Feline M/D n=5). However, some marked and persistent hyperglycaemia control cats for the male Somali cat (case of the cats were initially treated with an and glycosuria at the time of diagnosis 16), consequently this cat was excluded oral hypoglycaemic agent (glipizide, see Table 1. Causes of death in the 14 diabetic cats which have died Cause of death/euthanasia Numbers Cases Details of diagnostic findings Other information Heart failure 6/14 2, 4, 7, 10, 13, 16* See Tables 2 and 3 One died, five euthanased Chronic renal failure 2/14 17, 18 Azotaemia, cachexia and Two euthanased persistent polyuria In spite of reasonable control of the diabetes, based on fructosamine and plasma glucose monitoring Poor diabetic 2/14 9, 12 Persistent/frequent hyperglycaemia 2 euthanased control: ‘‘unstable’’ and glycosuria Elevated fructosamine One (12) treated with glipizide only Owners persisted with treatment for Other (9) treated 17 (case 9) and 16 months with PZI insulin (case 12) respectively. once a day Hypoglycaemia with convulsions 1/14 19 Hypoglycaemia. Neurological signs Euthanased persisted after euglycaemia Owner, a doctor, was achieved was managing this cat’s diabetes herself Owner requested 1/14 15 Euthanased euthanasia without treatment (three days after diagnosis) Profound anaemia 1/14 14 Investigation not permitted by owner Euthanased Sudden death 1/14 8 Glycaemic control being attempted Died with glipizide *This cat was a male Somali and no matched controls were available. It was omitted from the case-control analyses Table 2. History and diagnostic findings used to diagnose heart failure in six diabetic cats Case Interval between History at Physical examination. Plasma Radiography ECG Echo Pleural effusion Ascites Outcome diagnosis of diabetes time of Findings at time of [T4] and development of diagnosis diagnosis of heart failure of heart failure heart failure 2 10 weeks nappetence T38°C 21Á6 nmo / Patchy ncrease n S nus rhythm 1 (see Tab e 3) Scant effus on after – Euthanased we ght oss HR 164 bpm pu monary dens ty atter y frequent d abetes had been 10 months dyspnoea RR 80 brpm a r bronchograms ventr cu ar present for 12 months after d agnos s dyspnoea card omega y premature severe effus on three of heart fa ure hyperpnoea VHS 11Á5 comp exes weeks ater nsp ratory crack es on auscu tat on 10 30 months Du abdom na T37Á4°C Not done Not done S nus 1 (see Tab e 3) 250 m mod fied Large vo ume Euthanased swe ng HR 120 bpm bradycard a transudate mod fied one week after anorex a RR 40 brpm TP 38 g/ transudate d agnos s of m d dehydrat on Tr g 0Á47 mmo / TP 34 g/ heart fa ure co d p nnae Cho 2Á2 mmo / and feet Not cons stent w th chy e 7 16 months Du ness T38Á5°C Not done P eura effus on Not perm tted