J Vet Intern Med 2001 Nov-Dec;15(6):530-8
Breed risk of pyometra in insured dogs in Sweden.
Egenvall A, Hagman R, Bonnett BN, Hedhammar A, Olson P, Lagerstedt AS.
Department of Ruminant Medicine and Veterinary Epidemiology, Faculty of
Veterinary Medicine, Swedish University of Agricultural Sciences, Uppsala.
An animal insurance database containing data on over 200,000 dogs was used
to study the occurrence of pyometra with respect to breed and age during
1995 and 1996 in Swedish bitches <10 years of age. A total of 1,803 females
in 1995 and 1,754 females in 1996 had claims submitted because of pyometra.
Thirty breeds with at least 800 bitches insured each year were studied using
univariate and multivariate methods. The crude 12-month risk of pyometra for
females <10 years of age was 2.0% (95% confidence interval = 1.9-2.1%) in
1995 and 1.9% (1.8-2.0%) in 1996. The occurrence of pyometra differed with
age, breed, and geographic location. The risk of developing pyometra was
increased (identified using multivariate models) in rough Collies,
Rottweilers, Cavalier King Charles Spaniels
, Golden Retrievers, Bernese
Mountain Dogs, and English Cocker Spaniels compared with baseline (all other
breeds, including mixed breed dogs). Breeds with a low risk of developing
the disease were Drevers, German Shepherd Dogs, Miniature Dachshunds,
Dachshunds (normal size), and Swedish Hounds. Survival rates indicate that
on average 23-24% of the bitches in the databases will have experienced
pyometra by 10 years of age. In the studied breeds, this proportion ranged
between 10 and 54%. Pyometra is a clinically relevant problem in intact
bitches, and differences related to breed and age should be taken into
account in studies of this disease.