INCREASING INCIDENCE OF HEREDITARY INTRAHEPATIC PORTOSYSTEMIC SHUNTS IN IRISH WOLFHOUNDS IN THE NETHERLANDS (1984 TO 1992)

Because of the frequency with which Irish wolfhounds were observed to have intrahepatic partosystemic shunts, the concentration of ammonia w as measured in samples of venous blood taken at seven to eight weeks o ld from the 1066 Irish wolfhounds born in the Netherlands between 1984 and 1992, The average rate of incidence of the condition (defined as an ammonia concentration exceeding 150 mu M) over this period was 2.1 per cent and it increased (P<0.03) at an average annual rate of 0.34 p er cent, The genetic similarity between the individual dogs with porto systemic shunts, defined by their degree of relationship (R(pq)), was significantly higher (P<0.00001) than either the R(pq) among the contr ol dogs which had an ammonia concentration below 46 mu M or the R(pq) between the affected dogs and the controls, Furthermore, the mean ammo nia concentration in clinically normal Irish wolfhounds was higher tha n that in the healthy control dogs of various breeds (73.8 v 33.4 mu M ). The overrepresentation of portosystemic shunts in Irish wolfhounds, the increasing rate of incidence of the shunts, and the familial dist ribution of the animals with the condition are evidence for a heredita ry basis for the disorder in this population.