Livestock Production Science 63 2000 275–289 www.elsevier.com locate livprodsci
Estimates of longevity and causes of culling and death in Swedish warmblood and coldblood horses
a , a
a b
¨ Lena Wallin
, Erling Strandberg , Jan Philipsson , Goran Dalin
a
Department of Animal Breeding and Genetics , Swedish University of Agricultural Sciences, S-750 07 Uppsala, Sweden
b
Department of Anatomy and Histology , Swedish University of Agricultural Sciences, S-750 07 Uppsala, Sweden
Received 26 October 1998; received in revised form 6 May 1999; accepted 15 June 1999
Abstract
Data on several different horse populations were analysed and compared regarding length of life and diseases or injuries leading to death or culling. In order to include information for horses still alive, a failure time survival analysis was used.
The first material included 1847 warmblood horses born between 1968 and 1982, that had participated in the Swedish Riding Horse Quality Test RHQT as 4-year-olds. The next two materials included 344 warmblood and 204 coldblood horses
owned by the Swedish Cavalry Horse Foundation CHF, born between 1970 and 1975. The last population consisted of 481 warmblood brood-mares born between 1965 and 1967. According to this study it was important to estimate the median
length of life separately for each sex. For warmblood brood-mares and mares that had participated in the RHQT, comparable figures of 18.6 and 18.3 years were found. Close agreement was also found between geldings of the CHF and males that had
participated in the RHQT; the estimates were 14.7 and 13.9 years, respectively. There was a positive trend in the median length of life over time for horses that had participated in the RHQT, and the median length-of-life curve increased more
steeply for mares than for males. This study showed a longer median length of life for coldblood geldings, 17.6 years, than for the mares, 16.4 years. The most common causes of death of warmblood horses were diseases of the musculoskeletal
system 56–57, respiratory diseases 8–9, diseases of the digestive system 5–6 and accidents 3–9. The primary causes of death of coldblood horses were temperamental disorders 23, diseases of the musculoskeletal system 14 and
hoof diseases 8.
2000 Elsevier Science B.V. All rights reserved.
Keywords : Horses; Survival; Length of life; Culling; Death; Disease; Injury
1. Introduction tions of insurance statistics regarding length of life
gave rise to a debate about equine longevity. An In recent years, claims have been made that the
estimated average age of 7 to 8 years, based on lifespan of horses is shortening. Doubtful interpreta-
insurance data, was incorrectly interpreted in the horse journals as expected lifespan for all horses in
the population JFB, 1986. However, estimates of
Corresponding author. Tel.: 146-18-671955; fax: 146-18-
average age at culling in the insurance data were
672648. E-mail address
: Lena.Wallinhgen.slu.se L. Wallin
calculated only from the ages of dead horses where
0301-6226 00 – see front matter
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276 L
. Wallin et al. Livestock Production Science 63 2000 275 –289
compensation had been granted. These estimates were never found 30. Among those traced, the
should not be confused with the average expected response frequency to the questionnaires was 78.
life span of all horses in the population, because of Ninety-nine horses had been exported and were not
lack of information on horses still alive and on included in the study due to lack of information
horses not compensated for at death. Such estimates about their health status. The number of horses
would therefore most likely underestimate length of finally included in the study was 1847, 503 of whom
life Ohlsson, 1990. were dead. The distribution between mares and
Survival analysis, a statistical technique that can males was fairly even 864 983. Of the males 74
use information on horses still alive, so-called cen- were stallions at the time of the test. Information
sored data, is a more appropriate way to estimate the about the horses was available until 1990. Horse
length of life of horses. More accurate estimates of owners were asked if particular horses were alive or
length of life would bring better information to the dead and, if dead, to state the cause and year of
debate about equine longevity. death. When analysing the questionnaires, no distinc-
Reports summarising causes of death in sports tion was made between horses that died and those
horses are rare. Many studies mention a specific that were put down, because death was considered to
disease affecting horses and are often based on a be due to the causes mentioned in the questionnaires.
relatively selected group of horses Baker and Ellis, The date of birth ranged from 1968 to 1982 Fig.
1981. Available statistics are based mostly on 1. The horses were usually 4 years old when they
insurance data or veterinary clinical studies. Accord- participated in the test, the oldest horses in the
ing to insurance statistics, diseases of the musculo- material could have reached an age of 22, whereas
skeletal system are the predominant cause of death of horses born in 1982 could not have been more than 8
sports horses Clausen et al., 1990; AGRIA, 1995; years old. When the test started in 1973, participation
Heisele, 1995. Among ‘companion’ horses kept as a was limited because all horses were judged at only
hobby, diseases of the digestive system are the most one location in Sweden. Later, more places became
frequent cause of death Baker and Ellis, 1981. available and interest in participating increased.
Other than insurance statistics, recent reports on The horses included in the study had been used for
length of life and the most important causes of death different purposes — many of them for more than
in horse populations are scarce. This emphasizes the one purpose Table 1. Most horses 85 had been
need to find unselected materials in order to establish competing in different disciplines. It was quite
appropriate benchmarks. The aims of this inves- common that horses competing at a novice level had
tigation, therefore, were to estimate median length of results in several disciplines, whereas horses compet-
life and to analyse and compare causes of death in ing at an advanced level had results only in one of
different Swedish horse populations representative of the disciplines. An earlier study Ohlsson and Philip-
their breeds and normal use. sson, 1992 showed that horses with high scores in
the test had competed more successfully than the others at advanced levels. Many brood-mares had
2. Materials competition results as well. It was not unusual that
