Polycystic kidney disease in bull terriers: an autosomal dominant inherited disorder

Diagnosis and Surgical Treatment of a Renal Cyst Causing Unilateral Lameness in a Golden Eagle (Aquila chrysaetos)

This report describes the diagnosis and treatment of a benign renal cyst in an adult, female golden eagle (Aquila chrysaetos) presented for unilateral leg lameness. A cyst at the cranial division of the left kidney was diagnosed by computed tomography and was suspected of compressing the lumbosacral nerve plexus, resulting in limb lameness. The renal cyst was incompletely excised because the cyst wall was closely adhered to the kidney parenchyma and local blood supply. Fluid analysis and surgical biopsy of the cyst and left kidney confirmed the diagnosis of a benign renal cyst. No evidence of an infectious, inflammatory, or neoplastic etiology was noted. Postoperatively, the eagle's lameness resolved and the bird was ultimately released following recovery. During treatment for the renal cyst, the eagle was concurrently found to have increased serum titers on elementary body agglutination for Chlamydia psittaci and a positive titer for Aspergillus species antibody testing. The bird was administered doxycycline, azithromycin, and voriconazole for treatment of these potential pathogens prior to release. Unfortunately, the eagle was found dead 86 days postrelease due to an unknown cause. To the authors' knowledge, this is the first report of a golden eagle with a benign solitary renal cyst causing unilateral lameness secondary to nerve compression that was resolved with surgical excision.

Perioperative characteristics, histologic diagnosis, complications, and outcomes of dogs undergoing percutaneous drainage, sclerotherapy or surgical management of intrarenal cystic lesions: 18 dogs (2004-2021)

BACKGROUND

Canine intrarenal cystic lesions (ICLs) are infrequently reported in the veterinary literature. Several treatment options have been described including cyst fenestration (partial nephrectomy/deroofing) +/- omentalization, sclerotherapy using alcohol as a sclerosing agent, percutaneous cyst drainage (PCD), and ureteronephrectomy. Information regarding presenting clinical signs, physical examination findings, histologic diagnosis and outcomes of dogs with ICLs treated by different methods is limited. Medical records of 11 institutions were retrospectively reviewed to identify dogs that underwent PCD, sclerotherapy, surgical deroofing +/- omentalization, or ureteronephrectomy for management of ICLs from 2004 to 2021. Six weeks postoperative/post-procedural follow-up was required. Cases suspected to represent malignancy on preoperative imaging were excluded. The study objective was to provide information regarding perioperative characteristics, complications, and outcomes of dogs undergoing treatment of ICLs.

RESULTS

Eighteen dogs were included, with 24 ICLs treated. Ten had bilateral. There were 15 males and 3 females, with crossbreeds predominating. PCD, sclerotherapy, deroofing and ureteronephrectomy were performed in 5 (5 ICLs treated), 7 (11 ICLs), 6 (6), and 7 (7) dogs, respectively, with 5 dogs undergoing > 1 treatment. Seven dogs experienced 8 complications, with requirement for additional intervention commonest. PCD, sclerotherapy and deroofing resulted in ICL resolution in 0/5, 3/11 and 3/6 treated ICLs, respectively. Histopathology identified renal cysts (RCs) in 7/13 dogs with histopathology available and neoplasia in 6/13 (4 malignant, 2 benign). Of 5 dogs diagnosed histopathologically with neoplasia, cytology of cystic fluid failed to identify neoplastic cells. Among 7 dogs with histologically confirmed RCs, 4 had concurrent ICLs in ipsilateral/contralateral kidney, compared with 2/6 dogs with histologically confirmed neoplasia.

CONCLUSIONS

Benign and neoplastic ICLs were approximately equally common and cystic fluid cytology failed to differentiate the 2. Among renal-sparing treatments, deroofing most commonly resulted in ICL resolution. Presence of concurrent ICLs in ipsilateral/contralateral kidney does not appear reliable in differentiating benign from malignant ICLs.

Role of chemokines, innate and adaptive immunity

Polycystic Kidney Disease (PKD) triggers a robust immune system response including changes in both innate and adaptive immunity. These changes involve immune cells (e.g., macrophages and T cells) as well as cytokines and chemokines (e.g., MCP-1) that regulate the production, differentiation, homing, and various functions of these cells. This review is focused on the role of the immune system and its associated factors in the pathogenesis of PKDs as evidenced by data from cell-based systems, animal models, and PKD patients. It also highlights relevant pre-clinical and clinical studies that point to specific immune system components as promising candidates for the development of prognostic biomarkers and therapeutic strategies to improve PKD outcomes.

Monkeys mutant for PKD1 recapitulate human autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) caused by PKD1 mutations is one of the most common hereditary disorders. However, the key pathological processes underlying cyst development and exacerbation in pre-symptomatic stages remain unknown, because rodent models do not recapitulate critical disease phenotypes, including disease onset in heterozygotes. Here, using CRISPR/Cas9, we generate ADPKD models with PKD1 mutations in cynomolgus monkeys. As in humans and mice, near-complete PKD1 depletion induces severe cyst formation mainly in collecting ducts. Importantly, unlike in mice, PKD1 heterozygote monkeys exhibit cyst formation perinatally in distal tubules, possibly reflecting the initial pathology in humans. Many monkeys in these models survive after cyst formation, and cysts progress with age. Furthermore, we succeed in generating selective heterozygous mutations using allele-specific targeting. We propose that our models elucidate the onset and progression of ADPKD, which will serve as a critical basis for establishing new therapeutic strategies, including drug treatments.

Renal ultrasonographic abnormalities are associated with low glomerular filtration rate calculated by scintigraphy in dogs

Ultrasound provides information on kidney morphology, but studies relating structural and functional abnormalities in chronic kidney disease (CKD) are lacking. The aim of this descriptive cross-sectional study was to compare individual kidney (IK) B-mode ultrasound abnormalities to IK glomerular filtration rate (GFR) estimated by scintigraphy normalized to plasma volume (PV) in dogs, to evaluate if ultrasonographic findings were associated with low IKGFR/PV. Eighty privately owned dogs with and without clinical suspicion of CKD were prospectively enrolled, and kidney ultrasound and IKGFR/PV were evaluated independently. Ultrasound images were assessed retrospectively for subjective abnormalities (shape, cortical, and medullary hyperechogenicity), and kidney size was measured. The normal IKGFR/PV cutoff was derived from dogs in the study group with no history and clinical signs of kidney disease and normal blood and urine results (n = 28) and was 16.84 mL/min/L. Kidneys were categorized into normal, mild, moderate, and severe ultrasound changes according to subjective ultrasound grades. Associations were found between low IKGFR/PV and abnormal kidney shape (P = .0004), cortical hyperechogenicity (P = .0008), medullary hyperechogenicity (P < .0001), and low kidney volume (P = .0092). Apart from the moderate and severe category comparison, IKGFR/PV value significantly decreased with increasing severity of category. The combination of ultrasonographic subjective abnormalities had a high sensitivity (93.8%) and moderate specificity (65.7%) for detecting low IKGFR/PV. Kidneys with normal IKGFR/PV had a low frequency of mild ultrasound changes. Findings indicate kidneys with increasing number and grade of subjective ultrasound abnormalities are more likely to have a lower IKGFR/PV.

Polycystic Kidney-like Disease in a Red-ear Slider Turtle (Trachemys scripta elegans)

A 14-year-old red-ear slider turtle (Trachemys scripta elegans) with no history of pre-existing clinical disease died and was referred for necropsy examination. Grossly, oesophageal prolapse, bilateral renal cysts and a paraduodenal cystic mass were detected. Tissues were processed routinely for histology and immunohistochemistry (IHC) with primary antibodies specific for Wilm's tumour suppressor gene-1 (WT-1), insulin, glucagon and pancytokeratins. Microscopically, renal medullary cysts and medullary atrophy resembled the changes associated with polycystic kidney disease (PKD). The cysts of the paraduodenal mass were lined by ciliated epithelial cells resembling embryonal cells and were intensely positive for glucagon and insulin by IHC. There was no cytokeratin expression in either lesion. WT-1 expression in the paraduodenal mass was cytoplasmic and appeared non-specific. Lesions were consistent with renal PKD-like disease and a pancreatic cystic hamartoma.

A splice site variant in INPP5E causes diffuse cystic renal dysplasia and hepatic fibrosis in dogs

Ciliopathies presenting as inherited hepatorenal fibrocystic disorders are rare in humans and in dogs. We describe here a novel lethal ciliopathy in Norwich Terrier puppies that was diagnosed at necropsy and characterized as diffuse cystic renal disease and hepatic fibrosis. The histopathological findings were typical for cystic renal dysplasia in which the cysts were located in the straight portion of the proximal tubule, and thin descending and ascending limbs of Henle’s loop. The pedigree of the affected puppies was suggestive of an autosomal recessive inheritance and therefore, whole exome sequencing and homozygosity mapping were used for identification of the causative variant. The analyses revealed a case-specific homozygous splice donor site variant in a cilia related gene, INPP5E: c.1572+5G>A. Association of the variant with the defect was validated in a large cohort of Norwich Terriers with 3 cases and 480 controls, the carrier frequency being 6%. We observed that the identified variant introduces a novel splice site in INPP5E causing a frameshift and formation of a premature stop codon. In conclusion, our results suggest that the INPP5E: c.1572+5G>A variant is causal for the ciliopathy in Norwich Terriers. Therefore, genetic testing can be carried out in the future for the eradication of the disease from the breed.

Inflammation and Fibrosis in Polycystic Kidney Disease

Polycystic kidney disease (PKD) is a commonly inherited disorder characterized by cyst formation and fibrosis (Wilson, N Engl J Med 350:151-164, 2004) and is caused by mutations in cilia or cilia-related proteins, such as polycystin 1 or 2 (Oh and Katsanis, Development 139:443-448, 2012; Kotsis et al., Nephrol Dial Transplant 28:518-526, 2013). A major pathological feature of PKD is the development of interstitial inflammation and fibrosis with an associated accumulation of inflammatory cells (Grantham, N Engl J Med 359:1477-1485, 2008; Zeier et al., Kidney Int 42:1259-1265, 1992; Ibrahim, Sci World J 7:1757-1767, 2007). It is unclear whether inflammation is a driving force for cyst formation or a consequence of the pathology (Ta et al., Nephrology 18:317-330, 2013) as in some murine models cysts are present prior to the increase in inflammatory cells (Phillips et al., Kidney Blood Press Res 30:129-144, 2007; Takahashi et al., J Am Soc Nephrol JASN 1:980-989, 1991), while in other models the increase in inflammatory cells is present prior to or coincident with cyst initiation (Cowley et al., Kidney Int 43:522-534, 1993, Kidney Int 60:2087-2096, 2001). Additional support for inflammation as an important contributor to cystic kidney disease is the increased expression of many pro-inflammatory cytokines in murine models and human patients with cystic kidney disease (Karihaloo et al., J Am Soc Nephrol JASN 22:1809-1814, 2011; Swenson-Fields et al., Kidney Int, 2013; Li et al., Nat Med 14:863-868, 2008a). Based on these data, an emerging model in the field is that disruption of primary cilia on tubule epithelial cells leads to abnormal cytokine cross talk between the epithelium and the inflammatory cells contributing to cyst growth and fibrosis (Ta et al., Nephrology 18:317-330, 2013). These cytokines are produced by interstitial fibroblasts, inflammatory cells, and tubule epithelial cells and activate multiple pathways including the JAK-STAT and NF-κB signaling (Qin et al., J Am Soc Nephrol JASN 23:1309-1318, 2012; Park et al., Am J Nephrol 32:169-178, 2010; Bhunia et al., Cell 109:157-168, 2002). Indeed, inflammatory cells are responsible for producing several of the pro-fibrotic growth factors observed in PKD patients with fibrosis (Nakamura et al., Am J Nephrol 20:32-36, 2000; Wilson et al., J Cell Physiol 150:360-369, 1992; Song et al., Hum Mol Genet 18:2328-2343, 2009; Schieren et al., Nephrol Dial Transplant 21:1816-1824, 2006). These growth factors trigger epithelial cell proliferation and myofibroblast activation that stimulate the production of extracellular matrix (ECM) genes including collagen types 1 and 3 and fibronectin, leading to reduced glomerular function with approximately 50% of ADPKD patients progressing to end-stage renal disease (ESRD). Therefore, treatments designed to reduce inflammation and slow the rate of fibrosis are becoming important targets that hold promise to improve patient life span and quality of life. In fact, recent studies in several PKD mouse models indicate that depletion of macrophages reduces cyst severity. In this chapter, we review the potential mechanisms of interstitial inflammation in PKD with a focus on ADPKD and discuss the role of interstitial inflammation in progression to fibrosis and ESRD.

Demographics of polycystic kidney disease and captive population viability in pygmy hippopotamus (Choeropsis liberiensis)

Polycystic kidney disease (PKD) was previously diagnosed at necropsy in several pygmy hippopotami (Choeropsis liberiensis) from the Smithsonian National Zoo and Zoo Basel, suggesting a threat to the long-term viability of the captive population. We determined the incidence and demographics of PKD in the captive population historically; we tested if the condition is linked to pedigree; we investigated mode of inheritance; we examined effects of PKD on longevity; we conducted survival analysis; and we examined long-term population viability. Thirty-seven percent of 149 necropsied adult pygmy hippos were affected by PKD, and it was more common in females, controlling for the overall female-biased sex-ratio. Prevalence increased significantly with age, but most hippos were beyond their reproductive prime before developing clinical signs; thus fecundity was likely unaffected. PKD was linked to pedigree and may exhibit X-linked dominance, but further research is needed to definitively establish the mode of inheritance. PKD did not affect longevity, overall or within any age class. There was no significant correlation between inbreeding coefficient (F) and PKD, and the prevalence in wild-caught and captive-born animals was similar. Longevity for both captive-born and inbred hippos (F > 0) was significantly shorter than longevity for their wild-caught and non-inbred counterparts. Demographic projections indicated the extant population will likely experience a slow increase over time, provided there are no space constraints. We conclude that although PKD is an important cause of morbidity and mortality in pygmy hippos, the condition is not a primary concern for overall viability of the captive population.

Aquaporin-2 regulation in health and disease

Aquaporin-2 (AQP2), the vasopressin-regulated water channel of the renal collecting duct, is dysregulated in numerous disorders of water balance in people and animals, including those associated with polyuria (urinary tract obstruction, hypokalemia, inflammation, and lithium toxicity) and with dilutional hyponatremia (syndrome of inappropriate antidiuresis, congestive heart failure, cirrhosis). Normal regulation of AQP2 by vasopressin involves 2 independent regulatory mechanisms: (1) short-term regulation of AQP2 trafficking to and from the apical plasma membrane, and (2) long-term regulation of the total abundance of the AQP2 protein in the cells. Most disorders of water balance are the result of dysregulation of processes that regulate the total abundance of AQP2 in collecting duct cells. In general, the level of AQP2 in a collecting duct cell is determined by a balance between production via translation of AQP2 mRNA and removal via degradation or secretion into the urine in exosomes. AQP2 abundance increases in response to vasopressin chiefly due to increased translation subsequent to increases in AQP2 mRNA. Vasopressin-mediated regulation of AQP2 gene transcription is poorly understood, although several transcription factor-binding elements in the 5' flanking region of the AQP2 gene have been identified, and candidate transcription factors corresponding to these elements have been discovered in proteomics studies. Here, we review progress in this area and discuss elements of vasopressin signaling in the collecting duct that may impinge on regulation of AQP2 in health and in the context of examples of polyuric diseases.

Identification of porcine polycystic kidney disease 1 (PKD1) gene: molecular cloning, expression profile, and implication in disease model

The polycystic kidney disease 1 (PKD1) gene, which accounts for ~85% of human autosomal dominant polycystic kidney disease (ADPKD) cases, has been extensively studied in human and mouse. Much information about the pathogenesis of and treatments for ADPKD has been gained from the use of mouse models. However, because mouse models pose some limitations, further studies in other model systems are needed to investigate the biological basis of ADPKD. The pig is regarded as an important biomedical model. Thus, we isolated a pig PKD1 homolog and characterized its cDNA sequence, genomic structure, expression profile, alternative splicing, methylation status, protein characteristics, and immunohistochemical features in both neonatal and adult pigs. The pig PKD1 cDNA is 14,209bp long and encodes a 4305-residue polypeptide. The genomic sequence of PKD1 is ~50kb with 46 exons. An alternative splice acceptor site was identified in intron 9. PKD1 is expressed in all tissues tested in both neonatal and adult pigs and exhibits a developmentally regulated expression pattern. Western blotting revealed that the molecular mass of polycystin-1 is ~460kDa, but its expression level is relatively low. Immunohistochemical study of the kidneys shows that polycystin-1 is mainly expressed in the tubular epithelia. Bisulfite methylation analysis of CpG islands in the promoter region does not show a direct correlation between methylation status and expression level among different tissues/cells. The cloning and characterization of pig PKD1 indicates that the pig and human genes are highly similar in length of genomic and cDNA sequences, genomic structure and context, expression patterns, conserved transcription factor binding sites, and the molecular mass of the encoded polycystin-1. These data support our current understanding of PKD1, and suggest that the pig is an ideal candidate for development of an ADPKD disease model.

Juvenile nephropathy in a Boxer dog resembling the human nephronophthisis-medullary cystic kidney disease complex

A juvenile nephropathy in a 4-year-old male Boxer dog, closely resembling the Nephronophthisis (NPHP)-Medullary Cystic Kidney Disease Complex (MCKD) in humans is described. Gross examination of the kidneys revealed several multiple cysts at the corticomedullary junction and in the medulla. Histological examination was characterized by a widespread tubular atrophy and dilatation, with a marked thickening of the tubular basement membrane, interstitial lymphocytic infiltration and fibrosis. Ultrastructural studies revealed dilated tubules with irregular basement membrane thickening and splitting. Lectin histochemistry investigation revealed that the cysts originated in the distal convoluted tubule and collecting duct. Having excluded all other known cystic diseases of the kidney, and based on the lectin histochemistry results, the macroscopic and histological findings of our case are highly compatible with a diagnosis of the NPHP-MCKD complex. To our knowledge, this is the first report describing this particular lesion.

A non-synonymous mutation in the canine Pkd1 gene is associated with autosomal dominant polycystic kidney disease in Bull Terriers

Polycystic Kidney Disease is an autosomal dominant disease common in some lines of Bull Terriers (BTPKD). The disease is linked to the canine orthologue of human PKD1 gene, Pkd1, located on CFA06, but no disease-associated mutation has been reported. This study sequenced genomic DNA from two Bull Terriers with BTPKD and two without the disease. A non-synonymous G>A transition mutation in exon 29 of Pkd1 was identified. A TaqMan® SNP Genotyping Assay was designed and demonstrated the heterozygous detection of the mutation in 47 Bull Terriers with BTPKD, but not in 102 Bull Terriers over one year of age and without BTPKD. This missense mutation replaces a glutamic acid residue with a lysine residue in the predicted protein, Polycystin 1. This region of Polycystin 1 is highly conserved between species, and is located in the first cytoplasmic loop of the predicted protein structure, close to the PLAT domain and the second transmembrane region. Thus, this change could alter Polycystin 1 binding or localization. Analytic programs PolyPhen 2, Align GVGD and SIFT predict this mutation to be pathogenic. Thus, BTPKD is associated with a missense mutation in Pkd1, and the application of this mutation specific assay could reduce disease transmission by allowing diagnosis of disease in young animals prior to breeding.

Linkage confirms canine pkd1 orthologue as a candidate for bull terrier polycystic kidney disease

Bull terrier polycystic kidney disease (BTPKD) is a Mendelian disorder with many features reminiscent of human autosomal dominant polycystic disease, the latter disease being due to mutations at PKD1 and PKD2 loci. We investigated the role of the canine pkd1 orthologue in BTPKD via linkage analysis of a large kindred in which the disorder is segregating. Twelve microsatellite markers around the canine pkd1 locus (CFA6) were amplified from the genomic DNA of 20 affected and 16 unaffected bull terriers. An additional 28 affected dogs were genotyped at five key microsatellites. A highly significant multi-point LOD score that peaked over the canine pkd1 locus was observed (LOD = 6.59, best two-point LOD score LOD = 6.02), implicating this as the BTPKD locus.

Polycystic kidney disease in adult Brazilian agoutis (Dasyprocta leporina)

During the last 21 years, 7 adult captive Brazilian agoutis (Dasyprocta leporina) from 4 different zoologic gardens were necropsied and histologically examined at the Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany. All animals had polycystic kidney disease as the major pathologic change. Except in 1 case, no clinical signs were recognized prior to death. The animals had macroscopic bilateral alterations of the kidneys ranging from granulated surfaces to severe polycystic changes. Microscopic examination revealed multifocal to generalized, moderate to severe cystic dilatations of Bowman's capsules and renal tubules, moderate mesangial and capsular proliferation of the renal corpuscles, mild interstitial fibrosis, and mild to moderate interstitial lympho-plasmacytic infiltrations. Little information is known about the genetic relationships of these animals, but breeding practice indicates a high possibility of inbred agouti zoo populations in Germany. This is the first report on polycystic kidney disease in Brazilian agoutis with possible genetic background.

Congenital polycystic kidney disease in lambs

AIM

To describe the pathology and inheritance of a congenital polycystic kidney disease (PKD) of sheep.

METHODS

Mode of inheritance of PKD was investigated by evaluation of results of the disorder from planned matings in two consecutive years within subsets of a flock that had a high prevalence of PKD in lambs. Gross pathological and histopathological studies were based on tissues derived from this study. Haematoxylin and eosin (H&E)-stained paraffin sections of kidney, liver, extrahepatic biliary and pancreatic ducts, pancreas and epididymis were used to describe the lesions.

RESULTS

Twenty-five lambs affected by PKD, of both sexes, were born, numbers in accord with those expected for an autosomal recessive disorder in the population studied. In all cases for which tissues were available, the renal, bile ductal (intrahepatic and extrahepatic), pancreatic and epididymal tissues had widespread dysplastic changes and associated cyst formation.

CONCLUSIONS

The findings of renal cysts in conjunction with cysts in other organs are unifying features in many of the human and animal forms of PKD and suggest a related pathogenic and genetic base consistent with an autosomal recessive disorder.

Auscultation and echocardiographic findings in Bull Terriers with and without polycystic kidney disease

OBJECTIVE

To investigate a possible association between Bull Terrier polycystic kidney disease (BTPKD) and cardiac disease, to determine the prevalence of mitral valve disease (MVD) and left ventricular outflow tract obstruction (LVOTO) in the Australian Bull Terrier population, and to compare auscultation and echocardiography in detection of cardiac disease in Bull Terriers.

DESIGN

Ninety-nine Bull Terriers, ranging in age from 8 weeks to 13 years and 11 months were auscultated and examined using renal ultrasonography; 86 were also examined using echocardiography. The prevalence and severity of heart defects in dogs with BTPKD was compared with that in dogs without BTPKD.

RESULTS

Nineteen of these 99 dogs were diagnosed with BTPKD. Forty-two percent of Bull Terriers with BTPKD and 28% of those without BTPKD had murmurs characteristic of mitral regurgitation or LVOTO. How recently an animal was descended from an ancestor with BTPKD was associated with presence (P = 0.008) and loudness of a murmur (P = 0.009). Overall, echocardiography detected MVD in 39% of Bull Terriers, with increased prevalence in older animals (P = 0.003). Mitral stenosis was found in eight cases. Fifty-three percent of dogs in this study had evidence of LVOTO, with obstruction consisting of a complex of lesions including dynamic or fixed subvalvular LVOTO, significantly narrowed left ventricular outflow tract or valvular aortic stenosis. Dogs with BTPKD, or those descended from dogs with BTPKD, were more likely to have MVD (P = 0.006), and while LVOTO was not more common in these dogs, if they did have LVOTO, they were more likely to have severe obstruction than dogs with no ancestors with BTPKD (analysed in three ways P = 0.028 to 0.001). In this study, 46% of Bull Terriers without a murmur or arrhythmia had cardiac disease detected on echocardiographic examination.

CONCLUSION

Cardiac disease, especially MVD and LVOTO, was common in Bull Terriers in this study, and those with BTPKD had an increased risk of cardiac abnormalities. Auscultation did not detect a significant number of Bull Terriers with cardiac disease.

Chronic renal failure in an English bull terrier with polycystic kidney disease

An entire female English bull terrier, aged five years and one month, was diagnosed with polycystic kidney disease by renal ultrasonography. It had thickening and abnormal motion of the mitral valve on 2D and M mode echocardiography, and left ventricular outflow tract obstruction, characterised by turbulence in the left ventricular outflow tract and elevated aortic blood flow velocity, detected by colour flow and spectral Doppler echocardiography, respectively. Two years later, haematology, serum biochemistry and urinalysis data suggested the presence of compensated renal failure. The dog was euthanased at 10 years and eight months of age, with haematology, serum biochemistry and urinalysis data Indicating decompensated chronic renal failure. Postmortem examination confirmed polycystic kidney disease, chronic renal disease, mitral and aortic valvular myxomatous degeneration, and mixed mammary neoplasia. This case demonstrates that bull terriers with polycystic kidney disease may develop associated chronic renal failure.

Echocardiographic parameters in 14 healthy English Bull Terriers

OBJECTIVE

To determine the range of various cardiac parameters using echocardiography in apparently normal, healthy English Bull Terriers.

DESIGN

Fourteen English Bull Terriers were selected for study. Cardiac auscultation of the parents of these dogs was normal. Echocardiographic examination of one parent of each animal showed: no mitral or aortic valve abnormalities; no myocardial lesions; no two dimensional evidence of fixed or dynamic left ventricular outflow tract obstruction; and no systolic aortic or left ventricular outflow tract turbulence on colour flow Doppler examination. The 14 selected dogs did not have arrhythmias or murmurs, and on echocardiographic examination had similar findings to their parents. Systolic blood pressure was measured in all dogs and they had no clinical evidence of Bull Terrier polycystic kidney disease or Bull Terrier hereditary nephritis.

PROCEDURE

All dogs were auscultated and subjected to a sequential global echocardiographic assessment of the heart, including two dimensional long and short axis, and colour flow Doppler interrogation of the mitral and aortic valves. Dimensional measurements, including those from the left atrium, aortic annulus and left ventricle, were taken from a right parasternal window, and derived values such as fractional shortening, stroke volume and left atrial to aortic annulus ratio were calculated. Peak systolic aortic velocity was measured from the left parasternal window using two dimensional-guided pulsed wave Doppler with angle correction. Systolic blood pressure was measured using a Doppler monitor. The absence of Bull Terrier polycystic kidney disease was determined using renal ultrasonography, and of Bull Terrier hereditary nephritis using urinary protein to creatinine ratio.

RESULTS

These 14 dogs had greater left ventricular wall thickness and smaller aortic root diameters than those reported as normal for other breeds of comparable body size. Left atrial dimensions were also larger, however this may have been due to the "maximising" method of measurement. These apparently normal English Bull Terriers also had higher aortic velocities than those reported for other breeds, possibly due to a smaller aortic root diameter or other anatomic substrate of the left ventricular outflow tract, lower systemic vascular resistance, or breed-specific "normal" left ventricular hypertrophy. While these dogs were selected to be as close to normal as possible, the breed may have a particular anatomy that produces abnormal left ventricular echocardiographic parameters.

CONCLUSION

These echocardiographic parameters may be used to diagnose left ventricular outflow tract obstruction and left ventricular hypertrophy, and inaccurate diagnoses may result if breed-specific values are not used.

Renal pathology of polycystic kidney disease and concurrent hereditary nephritis in Bull Terriers

OBJECTIVE

To describe the renal lesions in Bull Terrier polycystic kidney disease (BTPKD), to confirm that the renal cysts in BTPKD arise from the nephron or collecting tubule, and to identify lesions consistent with concurrent BTPKD and Bull Terrier hereditary nephritis (BTHN).

DESIGN

Renal tissue from five Bull Terriers with BTPKD and eight control dogs was examined by light and transmission electron microscopy. Clinical data were collected from all dogs, and family history of BTPKD and BTHN for all Bull Terriers.

RESULTS

In BTPKD the renal cysts were lined by epithelial cells of nephron or collecting duct origin that were usually squamous or cuboidal, with few organelles. They had normal junctional complexes, and basal laminae of varying thicknesses. Glomeruli with small, atrophic tufts and dilated Bowman's capsules, tubular loss and dilation, and interstitial inflammation and fibrosis were common. Whereas the lesions seen in BTHN by light microscope were nonspecific, the presence of characteristic ultrastructural glomerular basement membrane (GMB) lesions and a family history of this disease indicated concurrent BTHN was likely in three of five cases of BTPKD.

CONCLUSION

This paper provides evidence that renal cysts in BTPKD are of nephron or collecting duct origin. In addition, GBM lesions are described that strongly suggest that BTPKD and BTHN may occur simultaneously.

Prevalence of autosomal dominant polycystic kidney disease in Persian cats and related-breeds in Sydney and Brisbane

OBJECTIVE

A form of autosomal dominant polycystic kidney disease has been identified in Persian cats and related breeds. Two features make elimination of this disease from future generations an achievable goal: the autosomal dominant mode of inheritance and the availability of a noninvasive technique, renal ultrasonography, to identify affected cats. The aims of this study were; to determine the prevalence of the disease in Persian cats and related breeds in Sydney and Brisbane, to determine any effect of domicile and breed on disease prevalence, to alert veterinary practitioners to the prevalence of autosomal dominant polycystic kidney disease and to propose methods of eliminating the disease from future generations of cattery-bred cats.

DESIGN

To be included in this scheme, cats had to be of Persian or related breed and be older than 10 months-of-age. Younger cats were excluded because of the increased likelihood of a false negative result. Renal ultrasonography was performed using either a Medison 600 with a 7.5 MHz mechanical sector scanner (n = 228, Brisbane) or using an ATL UltraMark-9 with a 5 to 10 MHz linear array transducer (n = 92, Sydney). The effects of domicile (Sydney versus Brisbane) and breed on the prevalence of autosomal dominant polycystic kidney disease were tested using two-tailed Fisher's Exact tests.

RESULTS

A total of 320 cats were tested comprising 230 Persians, 48 Himalayans, 17 Exotics, 14 Burmillas, 6 Ragdolls and 5 Chinchillas. The prevalence of autosomal dominant polycystic kidney disease in Sydney (45%) and Brisbane (42%) was comparable and no sex predilection was identified. The disease was not detected in Ragdolls, although only a small number was tested. Two of 14 Burmilla cats were positive (14%), demonstrating that long hair coat and brachycephalic features do not segregate with the polycystic kidney disease trait.

CONCLUSION

These results show that the prevalence of autosomal dominant polycystic kidney disease amongst purebred, long-haired cats in Australia is currently very high. Ultrasound detection schemes are easy to establish and breeder participation can be encouraged through subsidisation.

Feline polycystic kidney disease in Persian and other cats: a prospective study using ultrasonography

OBJECTIVE

To determine the prevalence of feline polycstic kidney disease in Persian cats presented to the University of Melbourne Veterinary Clinic and Hospital between February and August 1999.

DESIGN

A prospective clinical study using client owned animals was performed.

PROCEDURE

Two hundred and fifty Persian cats, ranging in age from 13 weeks to 10 years, were presented to the University of Melbourne Veterinary Clinic and Hospital for ultrasound examination of both kidneys. The cats were placed in dorsal and lateral recumbency and alcohol and ultrasonic coupling gel were applied to the skin. The kidneys were examined ultrasonographically in longitudinal, sagittal and transverse planes. Results were recorded for each cat at the time of examination as either negative or positive for PKD. In addition 14 Exotics (short-haired Persians), 4 Ragdolls and 3 British Short-Hair cats were examined.

RESULTS

Forty five percent of Persian cats examined were found to be positive for feline polycystic kidney disease on the basis of presence of anechoic cysts within the renal parenchyma. These cats ranged in age from 13 weeks to 10 years. Fifty per cent of the Exotic cats were positive for polycystic kidney disease whereas all Ragdolls and British Short Hairs were negative for the disease. Only one positive cat was reported to be showing clinical signs of renal disease.

CONCLUSION

The prevalence of feline polycstic disease in Persian cats presented to the University of Melbourne between February and August 1999 was 45%. Exotic cats were found to have the slightly higher incidence of 50%.