Post date: Oct 23, 2013 10:31:17 AM
Swedish research (Ref. 1) has published rankings for incidence of pyometra and mammary tumours in dogs, by breed. They examined Swedish insurance records for about 260,000 bitches, including 857 Longhaired Dachshunds (but not for other varieties and it is unclear whether the 857 includes all 3 FCI sizes).
Apparently, in Sweden 90% of bitches are unspayed, so this is a good population for such an assessment. In dogs up to 10 years of age, around one in four (28%) of the Dachshunds had been diagnosed with either or both pyometra and mammary tumour (average across all breeds 30%). This ranked Dachshunds 75 out of 110 breeds, making ours an average-risk breed.
Taken separately, pyometra was diagnosed in 15% (average 19%) and mammary tumour in 16% (average 13%). Obviously, if they had been able to include dogs older than 10, the rates might well have been even higher.
In our Dachs-Life 2012 Survey the prevalence of Mammary Tumours in Longhaired Dachshunds was just under 2.8% and was 3.6% overall across all six varieties of Dachshund. Pyometra was not reported as a specific condition in Dachs-Life 2012, but a small number of cases were reported as “other” conditions.
The top 10 breeds diagnosed with either or both of the two diseases in the Swedish paper were the Leonberger (73%), Irish Wolfhound (69%), Bernese Mountain Dog (69%), Great Dane (68%), Staffordshire Bull Terrier (66%), Rottweiler (65%), Bull Terrier (62%), Doberman (62%), Bouvier des Flandres (60%), Airedale Terrier (60%).
This does, of course, raise the question of whether or not bitches should be spayed to reduce the risks of Mammary Tumours. A study in 2012 (Ref. 2) set out to estimate the magnitude and strength of evidence for any effect of neutering, or age of neutering, on the risk of mammary tumours in bitches.
The researchers concluded:
There is some evidence to suggest that neutering bitches before the age of 2•5 years is associated with a considerable reduction in the risk of malignant mammary tumours, and that this risk may be reduced further by neutering before the first oestrous. However, our study, which involved screening over 10,000 articles in any language but reviewed only the English literature in detail, demonstrated that the strength of this evidence was weak because of the paucity of published studies that adequately address this issue. Two of the four included studies found no evidence that neutering bitches was associated with a reduced risk of mammary tumours; however, there were also potential biases in these results. This information should be balanced with other available information on the risks and benefits of neutering, including the potentially broader impact of unwanted pregnancies, for example.
In their Abstract, they say: Due to the limited evidence available and the risk of bias in the published results, the evidence that neutering reduces the risk of mammary neoplasia, and the evidence that age at neutering has an effect, are judged to be weak and are not a sound basis for firm recommendations.
The advice would seem, therefore, to be that each dog’s case needs to be considered individually and in thorough discussion with your veterinary surgeon.
You can read more advice on spaying and neutering here.
References:
1. S Jitpean, R Hagman, B Strӧm Holst, OV Hӧglund, A Pettersson and A Egenvall, Breed variations in the incidence of pyometra and mammary tumours in Swedish dogs, 2012, Reproduction in Domestic Animals 47 (Suppl. 6), 347–350
2. The effect of neutering on the risk of mammary tumours in dogs – a systematic review Journal of Small Animal Practice W. Beauvais, J. M. Cardwell, D. C. Brodbelt, Volume 53, Issue 6, pages 314–322, June 2012