LIFE-SPAN OF LONG AND ROUGH COATED DACHSHUNDS IN DEPENDENCE OF THEIR INBREED LEVEL AND SEX

Barbara Kosowska¹, Tomasz Strzała², Magdalena Moska², Joanna Kujałowicz¹, Ewa Oryszczak¹, Justyna Piecyk¹, Magdalena Sawczuk¹, Justyna Ślusarczyk¹, Katarzyna Wasilewska^1
1 Department of Genetics and Animal Breeding, Wrocław University of Environmental and Life Sciences, Poland
² Department of Genetics, Wrocław University of Environmental and Life Sciences, Poland

ABSTRACT

We report results presenting average life-span of two dog breeds: long coated dachshunds (average life-span 13.11 years) and rough coated dachshunds (average life-span 12.11 years). Also we describe relationship between life-span and inbreed level. Dogs were divided into two groups: experimental (inbreeded) and control. Long coated dachshunds from experimental group (with average inbreed level = 5.62%) were living on average 13.06 years. Rough coated dachshunds from experimental group (average inbreed level = 5.62%) were living on average 11.24 years. Average inbreed level within all long coated dachshund carried out 3.54 % while within rough coated 1.82%. Both differences between life-span among breeds and groups inside breeds were statistically significant. Furthermore interaction between sex and inbreeding level also had crucial influence on life span of both breeds.

Key words: life-span, long coated dachshunds, rough coated dachshunds, inbreeding, breed, sex.

INTRODUCTION

The life-span is multifactorial feature and depends in precise part from individual’s genotype as well as from influences of habitat. The Scandinavian investigations of monozygotic twins showed that inheritance of man's expected average life-span hesitated between 20 and 30% [8]. Therefore, the factors of habitat affects on life-span in 70-80%. The life-span was not up to here feature subjected to selection. In nature, this feature is a subject to the improvement on track of natural selection, making better the efficiency of species [11]. Executed on drosophilae works suggest, that selection directed on different features can also bear the fruit with enlargement of the life-span [10]. Positive result of such selection, proves the participation of genetic factors in the process of aging and shows on polygenous character of longevity [3]. How Smith showed [12], the maximum life-span is species specific feature, determined genetically. In grounds of species Canis lupus familiaris, this feature shows the considerable liability, however it is a rule that the dogs of large breeds live shorter [6]. Average life-span of studied dogs of different breeds was 13 years, and the oldest dog reached age 22 years. Average time of the dogs’ life according to different authors is specific for breed. Generally crossbreeds live longer than pedigree dogs. Michell [6] showed that hybrids live indeed longer than breed dogs, but there are breeds, which representatives live longer on the average than hybrids. They are rather small dogs – the miniature poodles, dachshunds as well as whippets. Differences in dogs life-span are reflection of breed specific genetic differences, resulting from selection of different features. Parker and co. [7]. showed that liability among dogs’ breeds is over 27% total genetic liability of this species. The wide range of breed specificities shows, that in some breeds on result of selection usage in connection with inbreeding, genes conditioning longer life could become consolidated. Compound between inbreeding level of standard poodle and length of their life was studied by Armstrong [1]. Author showed that the life-span had got smaller with growth of poodles inbreeding level. Similarly Smid [11], leading investigation on rhodesian ridgeback breed, suggested that individual’s inbreeding level could show compound with length of its life. Michell [6], showed that dachshunds make up group of the dogs’ living comparatively long. Moreover they are rather plentiful group of breeds, not only in the world but also in Poland. To improve the breed were used mostly selection and the inbreeding, in reasonable affinity. With this reason, dachshunds made up very good material for investigations, which purpose was the qualification of relationship between life-span of two races (long coated dachshunds – as well as rough coated dachshunds (standard varieties)), and value of their inbreeding factor.

MATERIALS AND METHODS

Research were lead in 2003-2004 and included males and females of the long-coated dachshund (134 individuals, 68 males and 66 females) as well as rough-haired dachshund (140 individuals, 53 males and 87 females) – both the standard varieties. All dogs were registered in Polish Kennel Club (ZKwP – member of FCI). We examined only dead males and females, deceased with natural causes. Life-span was defined by interview with owner. All dogs deceased of fate causes were eliminated from research. Then it was created (within both of studied breeds) the experimental groups (inbreeded males and females) as well as control (males and females free from inbreeding). Basing on four-generation pedigree, got from ZKwP, we estimated coefficient of inbreeding using Wright’s formula. Then calculated average values of life-span were compared between the experimental and supervisory groups as well as among sexes within the breeds and among breeds, by the multifactorial variation analysis.

RESULTS

The life-span average values with standard deviation (SD) of analyzed breeds are showed on fig. 1. Average values of inbreed level with SD are showed on fig. 2. Numerical and proportional share of individuals from experimental groups of both breeds divided into 5 classes with different inbreeding level, are showed on fig. 3. Overall variation analysis are placed in table 1.

Table 1. Significance of the influence of all variability sources (sex, inbreed, breed) for analyzed dogs life-span

Variability sources	Life-span
1. sex long-coated dachshunds – inbreeded group – control group rough-coated dachshunds – inbreeded group – control group	- -   - -
2. inbreed long-coated dachshunds rough-coated dachshunds	** (a=0.01) * (a=0.05)
breed n=139, 134 total 273	** (a =0.01)
Interactions	(a=0.05) (a=0.05)
4. sex x inbreed long-coated dachshunds rough-coated dachshunds
5. sex x breed	-
6. inbreed x breed	-
7. inbreed x sex x breed	-

Long-coated dachshunds

The average life-span of all long-coated dachshunds’ was 13.11 years. Individuals from control group lived 14 years and those from experimental group – 13.06 years (fig. 1). Individuals from control group made up near half of studied long-coated dachshunds’ rate (49.3 %) and lived almost about a year longer than inbreeded dogs. The difference between life-span from control and inbreeded groups has highly significant character (tab. 1) and with large possibility was the result of homozygosity among dogs from experimental group. Males and females from control group had different average life-span. Females, which made up over half of studied group (57.57 %). lived average 13.85 years, meanwhile males somewhat longer – 14.21 years. The difference was not statistically significant.

Fig. 1. Average life-span with SD for all individuals within breed, groups and sexes

Individuals from experimental group were inbreeded in variously (from about 1% to 25%. – fig. 3), average in 6.98 %. Participation of inbreeded individuals among all dogs was 50.7 %. In experimental group was also more females (58.82 %) than males. Average inbreeding level was 7.25 % among males, 6.8 % among females, and both inbreeded males and females lived on average 12.21 years (fig. 2). Sex did not differentiate life-span between inbreeded dogs (tab. 1). Average inbreed level of whole studied long-coated dachshunds’ population was 3.54 %.

Fig. 2. Average inbreed level (F) and SD for all dogs within breed, groups and sexes

Fig. 3. Numerical and proportional share of individuals from experimental groups of both breeds divided into 5 classes with different inbreeding level

Below on fig. 3. we illustrated numerical and proportional share of individuals from experimental groups of both breeds. divided into 5 classes with different inbreeding level. Among inbreeded long-coated dachshunds the most common inbreed level oscillated from 3 to 6 % (41.8% of all inbreeded long-haired dachshunds), second common was that about 3 % (31.3 % of individuals), third one from 9 to 12 % of inbreeding (13.4 % of individuals), 7.5 % had inbreed level between 6 and 9 %. and almost 6 % had relatively high inbreed level 25 %.

Rough-coated dachshunds

Average life-span of all studied rough-coated dachshunds was 12.11 years and in comparison with long-coated dachshunds was shorter about a year. This difference had highly significant character (table 1.). Dogs from control group made up 67.85 % of whole studied rough-coated dachshunds. It suggest that most of Polish rough-coated dachshunds are mated without inbreeding. The average inbreed level for whole breed carried out only 1.82 %, however for individuals from experimental group 5.62 %. Average life-span of dogs from control group was 12.51 years, in this 12.7 years for females (which were majority of this group – 63.15 %) and 12.2 years for males (fig. 1.). Average life-span of individuals from inbreeded group was 11.24 years, in this 11.8 years for females (which were 60% of all group) and only 10.4 years for males. The difference in life-span between control and experimental group. was over 1 year (1. 26 year) and had significant character (table 1). However the factor of sex did not have the influence on life-span in all groups.

Average inbreed level in experimental group accounted 5.62 %. More than a half of the individuals from inbreeded group (53.3 %) had rather low inbreed level – 3%, 31.1 % individuals – a bit higher – in borders 3-6%, and 6.6% of dogs had inbreed level oscillated between 6 and 12%. Very small percentage of individuals from this group (2.2 %), had the high inbreed level – 25-31% (fig. 3).

Generally females were more often represented within analyzed individuals than males (from 57.57% to 63.15%). Bigger loss of males was observed within rough-coated dachshunds (only 40% in experimental group and 43.3% in control group). Probably females from this breed are more popular than males. Besides, it can be assumed that according to the shorter average life-span of males, they had higher death-rate. The same problem was found among long-coated dachshunds. Among inbreeded long-coated dachshunds males were 41.2% individuals in an experimental group and 42,4% individuals in a control group. Both sexes of long-coated dachshunds had the same life-span, so the shortage of males could be result by unnatural death causes, which were not consider in our study.

Long-coated dachshunds had significantly longer life-span in comparison to rough-coated (fig. 1). In both groups, control and inbreeded, average life-span of long-coated dachshunds was 1.5 years longer than rough-coated. The difference is bigger when we analyzed only experimental groups. Long-coated dachshunds from inbreeded groups lived on average 13.04 years (average inbreed level 6.98%), while rough-coated dachshunds lived 1.5 years shorter (11.24 years) despite lower average inbreed level (5.62). Also interaction between sex and inbreed significant influenced on life-span both long and rough-coated dachshunds.

DISCUSSION

In our work we presented results applying to average life-span of long and rough coated dachshunds. Both differences in life-span between these two breeds and between two analyzed groups (inbreeded and control) were significant. That means firstly – that there are breed specific genes which have influence on life-span, secondly that even low inbreed level can be the factor which have influence on dogs life-span. Mean inbreed level within experimental groups of rough and long coated dachshunds was adequately 5.62 % (for whole breed – 1.82%) and 6.98% (for whole breed 3.54%). Drozd and Karpinski [1] estimated inbred level of four dog breeds. The highest average inbreed level was occurred within rottweilers (1.31% for whole breed and 5.74% for experimental group), then great dane’s (0.77% for whole breed and 7.60% for inbreeded group), boxer’s (0.74% for whole breed and 3.47% for experimental group) and german shepard’s (0.33% for whole breed and 2.48% for inbreeded group). Our results compared to other authors outcomes contains within the borders of other breeds inbreed levels. Long-coated dachshunds inbreed level is close to upper border compared to other breeds. This situation probably results from low amount of dogs from this breed (for example in years 1980-1993 in Lódz, only 35 long-coated dachshunds were registered).

The only author who analyzed connections between inbreed level and life-span was Armstrong (1998). He examined standard poodles divided into 4 groups with different inbreed level (to 6.25%, from 6 to 12.5%, from 12.5 to 25% and more than 25%). He showed that poodles from first class (to 6.25% inbreed level) lived on average 14 years, which was 4 years longer than dogs from class with the highest inbreed level. In our research average dachshunds life-span was shorter than dogs from Armstrong’s analysis (13.06 and 11.24 years). All dogs analyzed by Armstrong [1] had veterinary card and confirmed death cause. Poodles are also known as a long life dogs. Armstrong displayed potential poodles life-span as 15-16 years. From the other hand breeds which have very short life-span are great danes and mastiffs. The reasons of reduced life-span were according to Kaleta and Fiszdon [4] mostly tumors and intestines torsions. Rehfeld [9] showed that high inbreed level (18.6% to 37.6%) in beagles didn’t have influence on puppies survivability. Not before inbreed level 50% survivability came down from 70% to 46%. Michell [6] researched relation between British breeds life-span and body lengths, cardiological variables and diseases. He showed that average life-span for all breeds was 11 years and 1 month. Only 8% of dogs lived longer than 15 years. Smid [11] showed that rhodesian ridgeback’s average life-span was only 8.4 years, and that inbreed level do not have influence on life longitude. Inbreed level was estimated only for 27 individuals of that breed. In ours research within all 274 dogs only more than ten dogs which lived longer than 13 years had high inbreed level.

Life-span as a multimodular feature is dependant from many factors. Life-span inheritance is low and amount 20-30% in human [8]. In this small part inbreed level has it’s place. The inbreed influence is difficult to analyze even when inbreed level is constant due to the planned experiment [5]. In population investigations, the results suggesting influence of the homozygotic arrangements into polygenes should be interpreted carefully [6]. Especially during analysis such a complex feature like a life-span, on which the main influence had extragenetic factors [8]. We analyzed dogs which lived in a different environments, were feed on a different ways and the only common feature was breed and for some of them inbreeding level. Therefore the influence of inbreed, sex or breed on life-span should be the target of a future investigations.

REFERENCES

1. Armstrong J.B. 1998. Longevity in the standard poodle.http://www.caninegenetics.com/lifespan.html

2. Drozd L. Karpiński M.. 1997. Inbred wybranych ras psów wpisanych do Polskiej Księgi Rodowodowej [Inbreed of some dog’s breeds in Polish Kennel Club]. Annales Universitatis Mariae Curie Skłodowska. Sectio EE. vol. XV. 42:293-297 [in Polish].

3. Jazwinski S.M..1996. Longevity. genes. and aging. Science. 273: 54-63.

4. Kaleta T. Fiszdon K. 1999. Wybrane zagadnienia z genetyki i zachowania się psów [Some aspects from genetic and behaviour of dogs]. SGGW. Warszawa. s.: 58-72 [in Polish].

5. Kosowska B. Zdrojewicz Z. 1996. The relationship between inbreeding coefficient and sex hormones concentration. J.Bred. Genet. 113.2: 125-134.

6. Michell A.R. 1999. Longevity of British breeds of dog and its relationships with sex. size. cardiovascular variables and disease. Vet. Rec. 145: 625-629.

7. Parker H.G. Kim L.V. Sutter N.B.. 2004. Genetic structure of the purebred domestic dog. Science. 304: 1160-1164.

8. Perls T. Terry D. 2003. Understanding the determinants of exceptional longevity. Ann.Inter. Med. 139:445-449.

9. Rehfeld C.E. 1970. Definition of relationships in a closed beagle colony. Am. J. Vet.Res. 31:723-732.

10. Rose M.. Chalesworth B. 1980. A test of evolutionary theories of senescence. Nature. 287: 141-142.

11. Smid J. 2001. Increased mortality in Rhodesian Ridgebacks: The consequences of inbreeding depression. http://www.andycheah.com/files/rrlongevity.pdf

12. Smith D.W.E. 1995. Evolution of longevity in mammals. Mech. Age. Develop.. 81: 51-60.

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Barbara Kosowska
Department of Genetics and Animal Breeding,
Wrocław University of Environmental and Life Sciences, Poland
Kożuchowska 7, 51-631 Wrocław, Poland
email: basia@gen.ar.wroc.pl

Tomasz Strzała
Department of Genetics, Wrocław University of Environmental and Life Sciences, Poland
Kożuchowska 7
51-631 Wrocław
Poland
email: arrow00@poczta.fm

Magdalena Moska
Department of Genetics, Wrocław University of Environmental and Life Sciences, Poland
Kożuchowska 7
51-631 Wrocław
Poland
Phone +48 71 320 5921
email: magdalena.moska@up.wroc.pl

Joanna Kujałowicz
Department of Genetics and Animal Breeding,
Wrocław University of Environmental and Life Sciences, Poland
Kożuchowska 7, 51-631 Wrocław, Poland

Ewa Oryszczak
Department of Genetics and Animal Breeding,
Wrocław University of Environmental and Life Sciences, Poland
Kożuchowska 7, 51-631 Wrocław,

Justyna Piecyk
Department of Genetics and Animal Breeding,
Wrocław University of Environmental and Life Sciences, Poland
Kożuchowska 7, 51-631 Wrocław, Poland

Magdalena Sawczuk
Department of Genetics and Animal Breeding,
Wrocław University of Environmental and Life Sciences, Poland
Kożuchowska 7, 51-631 Wrocław, Poland

Justyna Ślusarczyk
Department of Genetics and Animal Breeding,
Wrocław University of Environmental and Life Sciences, Poland
Kożuchowska 7, 51-631 Wrocław, Poland

Katarzyna Wasilewska
Department of Genetics and Animal Breeding,
Wrocław University of Environmental and Life Sciences, Poland
Kożuchowska 7, 51-631 Wrocław, Poland

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