Hereditär nefrit hos bullterrier i Sverige
HereditärNefritBullterrierBasalmembranKollagenGlomeruliElektronmikroskopiUltrastrukturLamelleringFotutskottHistopatologiärftligNjursjukdomLjusmikroskopiPersisterandeProteinuriUrinproteinUrinkreatininTyp IV
Bull terrier hereditary nephritis is caused by a mutation that leads to an inadequate synthesis of collagen type IV, which is an important component in the basement membranes. The inheritance of the mutation is autosomal dominant in bull terriers and progression to renal failure takes variable time, from several months to ten years.
Proteinuria is the first clinical sign of the disease and the diagnosis is confirmed by transmission electron microscopy of renal tissue where typical ultrastructural changes in the glomerular basement membrane (GBM), thickening and multilaminar splitting are found.
This study was performed in order to find out the occurrence of hereditary nephritis in bull terriers in Sweden through examination of urine samples and renal tissue and comparisons with how the disease is described in the literature. Urine samples from 76 Swedish bull terriers were collected and examined for proteinuria. Dogs in heat or pregnancy were excluded. Three dogs had persistent proteinuria which was defined as a urinary protein creatinine ratio >0,5 in at least two urine samples taken at least one month apart, and in one of them a renal biopsy was performed.
Renal tissue for light and transmission electron microscopy from nine bullterriers that had been euthanized/died earlier because of renal disease were also evaluated.
In accordance with earlier studies the light microscopic changes found were non-specific and not diagnostic. Common lesions were fetal glomeruli (in adult dogs), larger glomerular tufts, adhesions between capillaries and Bowmans capsule, mesangial thickening, thickened and mineralized basement membranes, glomerular sclerosis, periglomerular fibrosis, cystic dilatation of Bowmans capsules with glomerular atrophy and protein content in the tubules. The ultrastructural abnormalities corresponded well to those described as specific for hereditary nephritis in earlier studies, including thickening and multilaminar splitting of the GBM. These changes in the GBM were seen in all the seven dogs that could be evaluated with electron microscopy.
The results suggest that hereditary nephritis occurs in the bull terrier breed in Sweden and that the disease can be diagnosed by clinical symptoms and light microscopy together with transmission electron microscopy. Urine specimens from a greater number of dogs, especially from suspected families, would further increase the knowledge about how widespread hereditary nephritis amongst bull terriers is in Sweden.