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2002 Diabetes UK. Diabetic Medicine, 19, 7779 77

Introduction

Dogs and cats have played a crucial role in the understanding

of diabetes and during the development of its therapies:

pancreatectomized dogs along with serependity [1] helped

von Minkowski and Mehring to understand that the pancreas

was essential to maintain blood glucose levels normal [2];

in 1913, the partially pancreatectomized female bullterrierB2-31 led Allan to the erroneous belief that the avoidance

of sugar consumption might represent a therapy for diabetes

[3]as the sugar-Verbotit has terrorized the life of millions

of people with diabetes during the past century [4]; in 1921,

the pancreatectomized beagle Majorie helped Banting to

prove for the first time that survival was possible by injections

of pancreatic extracts (later called insulin) [5] and Dr Lukens

cats demonstrated that overexposure to glucose could exhaust

the endocrine pancreas and thus bring about permanent

diabetes [6]. However, when dogs or cats became spon-

taneously diabetic, other than euthanasia very little medical

help was available to them up to quite recently. Around thediabetes publicity generated during the Annual Meeting of the

European Diabetes Association held in Dsseldorf in 1994,

we were contacted by a practising veterinarian as to whether

it would indeed be evidence-based to switch insulin treatment

in his canine diabetic patients from porcine to human insulin,

as had been suggested to him by some of their owners. This

request heralded a seminal change in the citys veterinary

practice, since during the 1960s diabetes treatment in dogs had

been practically unheard of. It led us to conduct a systematic

study of the frequency and nature of diabetes care in cats and

dogs in veterinarian practices in the city of Dsseldorf.

Methods

Dsseldorf is a city with a population of approximately

550 000 people and 16 000 dogs registered at the city council (as

an absolutely minimal estimate of the citys canine inhabitants).

In the summer of 1995 we contacted all 25 veterinarians

registered as practitioners in the city of Dsseldorf. Two of

them had already discontinued their practice at the time of

the survey, two were not willing to co-operate in the study. The

remaining 21 veterinarians were visited by one of us (T.P.N.)

during office hours in their practices. Information on the

quality and quantity of diabetes care currently provided for

cats and dogs in these practices was obtained by standardized

interviews comprising 24 questions and by extracting data

from respective patients files. Since in veterinary practices,

in general, no third-party payment system is operative, case

documentation is not necessarily as complete as in German

general practitioners offices.

Results and discussion

During the survey 52 dogs and 38 cats were identified as

diagnosed and subsequently treated diabetics; in 46 animals a

complete set of data comprising demographic characteristics,

details about therapy and achieved degree of metabolic control

as well as concerning the acute and late complications of thedisease was obtainable from the practice files.

In accordance with veterinary textbook information [7], of

the diabetic dogs, 57% were thoroughbred dogs, and 68%

female; of the diabetic cats, 3/4 of which belonged to the

ordinary European domestic cat type, 60% were male (about

half of which had been castrated before diabetes was diagnosed).

On average, the animals were quite old by the time diabetes

had been diagnosed: dogs (n= 52) mean 9 3 (SD) years (range

121 years); cats (n= 32) 12 4 years (624 years). At the time

of diagnosis, around 70% of the animals had been classified as

overweight by the veterinarians. In some cases, the veterinarians

had noted apparent precipitating causes for the manifestation

of the disease, such as corticoid therapy, infections, oestrogen/

progesterone treatment, or psychological stress, such as

jealousy or changes of location and/or owners.

The veterinarians diagnosed diabetes in the presence of

typical symptoms (polyuria, polydipsia, polyphagia, weight loss)

by measuring fasting venous glucose levels (20 veterinarians);

for one veterinarian clinical symptoms plus glucosuria was

sufficient to make the diagnosis. One difficulty in diagnosing

diabetes was the frequent occurrence of transient stress-

induced hyperglycaemia in cats; thus, reproducibility of

hyperglycaemia over time and values >15 mmol/l were taken

Correspondence to: Professor Michael Berger MD, Klinik fr

Stoffwechselkrankheiten und Ernhrung (WHO Collaborating Centre for

Diabetes), Heinrich-Heine Universitt Dsseldorf, Moorenstrasse 5, 40225

Dsseldorf, Germany. E-mail: bergermi@uni-duesseldorf.de

BlackwellScience,LtdOxford,UKDMEDiabeticMedicine0742-3071BlackwellScienceLtd, 2002January200219113OccasionalReportOccasionalreportDiabetescareincatsanddogsT.P.Neuvians&M. Berger

Diabetes care in cats and dogs

T. P. Neuvians and M. Berger

Department of Metabolic Diseases and Nutrition (WHO Collaborating Centre for Diabetes), Heinrich-Heine University Dsseldorf, Dsseldorf, Germany

Accepted 4 June 2001

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78 Diabetes care in cats and dogs T. P. Neuvians & M. Berger

as indicators of diabetes. One veterinarian relied also on

fructosamine determination, and in four practices oral glucose

tolerance tests were performed in doubtful cases. Opportunis-

tic screening for asymptomatic venous hyperglycaemia has

become routine in some practices.

In the cases in this study, at diagnosis fasting venous

glycaemia was 21.5 6.4 mmol/ l (n= 44; range 11.0

44.2 mmol/l) in dogs and 24.3 4.2 mmol/l (n= 34, range

12.333.1 mmol/ l) in cats. The veterinarians were well aware

of the particular pathogenic heterogeneity of diabetes in these

animals and the outstanding relevance of secondary diabetes

[7]; nevertheless, they argued that any effort to obtain a

differential diagnosis was not warranted as it had no conse-

quences for any therapeutic strategy.

In female dogs, with two exceptions, the veterinarians

favoured an ovario-hysterectomy as the first-line antidiabetic

treatment, especially in cases of menstrual cycle-associated

insulin resistance. This strategy is in line with veterinary

textbook recommendations for the therapy of diabetic dogs

and, although somewhat less straightforward, for femalediabetic cats [7]. In practice, however, this treatment was

carried out in only two of 27 (previously non-castrated) female

dogs, mainly because the animal owners did not consent or

because surgery was contraindicated due to the patients

advanced age and/or poor general condition. None of the

veterinarians used oral antidiabetic agents; in all practices,

diabetic dogs and cats with blood sugar values > 11.0 mmol / l

were immediately put on subcutaneous insulin therapy.

One veterinarian reported the successful additional use of a

homeopathic substance, Syzygium jambolanum (Myrtaceae).

In general, the initiation of insulin therapy was performed

on an ambulatory basis with repeated blood glucose measure-ments during the day, the frequency depending on the owners

co-operation; only two veterinarians admitted animals for this

purpose. On the whole, hospitalization was seen as too stress-

ful for both pet and owner. Adjustment of insulin dose to opti-

mize control was usually performed on the basis of blood

glucose measurements (e.g. fasting and post-prandial, or 4 h

and 8 h post-insulin injection, respectively) and occasionally

urine tests, carried out in the practices: one veterinarian regu-

larly measures serum fructosamine. All veterinarians asked

the owner to check the animals drinking behaviour and/or

body weight. Five practices recommend recording the animals

water consumption; 14 veterinarians handed out dry-chemistry

strips for regular or for occasional glucosuria monitoring to

the owners. Two veterinarians found it sufficient to adjust

insulin dosages based upon their patients clinical symptoms.

During therapy, office blood glucose levels for dogs (n= 41)

were 13.5 8.5 (range 3.338.9) mmol/l, and for cats (n= 31)

12.3 5.0 (range 4.627.6) mmol/ l.

All diabetic animals were treated with (medium-) long-

acting insulin preparations, once or twice daily. In most

cases bovine (Depot-CR in 13 practices) or porcine (Depot

CS in four practices) surfen insulin preparations and in

four practices a mixture of bovine and porcine insulin (Novo

lente) were used. Four veterinarians preferred human

insulin. The fact that amino acid sequences of porcine and dog

insulins are identical and of bovine and cat insulins almost

identical (except for a rare substitution in the A chain, i.e. the

substitution of His for Asn at position 18) did not appear to

play a role in the selection of insulin preparations. During

treatment, mean insulin dosages were for dogs (n= 27) 1.2

(range 0.32.3) U/kg body weight and for cats (n= 21) 1.0

(range 0.31.7) U/kg body weight.

Along with insulin therapy, various special diet regimens

were recommended, except for three veterinarians who

maintained the animals on their preferred nutritionin

order to avoid additional behavioural disturbances and

stress, especially in cats that are considered particularly

stress-susceptible. As in human diabetology [4], almost any

diet theoretically possible is advocated, mainly calorie-

reduced manufactured nutrition, e.g. enriched with fibre

and protein, or with reduced protein and carbohydrate

contents. It appears common to these diet food products

that they are expensive and that their advocates call for theirregular and exclusive use.

The success of diabetes care in the animals was reported

by the veterinarians as variable, dependent on the overall

status of the animal, the ease of combining insulin therapy

with predictable nutrition (with particular difficulties in the

stress-susceptible and often erratically behaving cats) and the

understanding and co-operation of the owners. Insulin therapy

was initiated in the vast majority of cases, only seldom did

owners ask for primary euthanasia. During the course of

treatment, discontinuation of therapy and/or euthanasia is

frequently opted for by the owners, mostly in cases in which

insulin treatment does not lead to an improvement of theanimals general condition (due to advanced age or concom-

itant diseases), if the animal appears to reject treatment

(mostly cats), and when owners feel overburdened by having

to carry out the treatment. Nevertheless, 13 veterinarians

reported diabetes treatment lasting for 24 years, three for

57 years and one had treated a diabetic cat for 10 years

with insulin.

During treatment, the most frequent acute complication

was hypoglycaemia (which was lethal in two cases); there was

no case of diabetic ketoacidosis. The veterinarians reported

frequent concomitant diseases and or complications such as

skin and urinary tract infections, fatty infiltration of the

liver and hyperlipoproteinaemia. By far the most frequent

diabetes-related complication in dogs was cataracts; four of 52

diabetic dogs were blind. In contrast, cataracts were only

rarely seen in diabetic cats. Clinically and on necropsy (two

cases) there were no apparent signs of vascular diabetic late

complications.

Conclusions

This report of a cross-sectional study on diabetes care reflects

the substantial importance of diabetes in a small-animal urban

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2002 Diabetes UK. Diabetic Medicine, 19, 7779

veterinary practice. With an estimated prevalence of 0.31.0%

in dogs and 0.10.3% in cats [8,9] diabetes represents a

relevant proportion of chronic diseases in household animals,

predominantly at a geriatric age. The growing number of dogs

and cats in big cities, their living conditions (resulting in

increasing body weight, decreasing physical activity and

increasing psychological stress) along with augmenting life

expectancy will lead to a dramatic increase in incidence

rates of diabetes in the future. On the other hand, it appears

that an increasing number of owners are prepared to accept

the burden in effort and expense associated with treating

their animals. As in human diabetology [4,10], much of the

current practice observed in this study is neither directed to

patient-orientated goals nor based on adequate evidence with

regard to efficacy and safety of diagnostic and therapeutic

interventions. Veterinarians, responsible animal owners and

animal protectionists should work together to formulate

evidence-based guidelines to be used in day-to-day veterinary

practice for education of animal owners and the exercise of

sensible diabetes care in cats and dogs.

Acknowledgements

We thank Professor Lotte Herberg DVM, MD (Dsseldorf)

and Professor Eleazar Shafrir MD, PhD ( Jerusalem) for their

help. M.B. had the original idea for the study and has written

the paper. T.P.N. is a DVM and carried out the study as part

of her MD thesis.

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