Progressive renal disease in Soft-coated Wheaten Terriers: possible familial nephropathy

Clinical and Histopathological Features of Renal Maldevelopment in Boxer Dogs: A Retrospective Case Series (1999-2018)

Simple Summary

This study describes clinical findings in Boxer dogs with renal maldevelopment and proposes a possible mode of inheritance. Medical records of 9 female Boxer dogs, older than 5 months and with a clinical diagnosis of proteinuric chronic kidney disease prior to one year of age, showed the presence of polyuria and polydipsia, decreased appetite, weight loss, lethargy and weakness in all affected dogs. Common laboratory findings were proteinuria and diluted urine, non-regenerative anemia, azotemia, hyperphosphatemia, hypoalbuminemia and hypercholesterolemia. Histopathology of the kidneys identified the presence of immature glomeruli in all dogs. In 7 out of 9 related dogs, the pedigree analysis showed that a simple autosomal recessive trait may be a possible mode of inheritance. Renal glomerular immaturity should be suspected in Boxer dogs with a history of polyuria, polydipsia, decreased appetite, weight loss, lethargy, weakness and proteinuria. A prompt diagnosis of renal maldevelopment, potentially hereditary, may help to evaluate if relatives of the affected dogs might be at risk, thus assisting clinicians in reaching an early diagnosis. A routine clinical renal screening evaluation in this breed, especially when this disease is suspected, should be strongly recommended.

Abstract

Renal maldevelopment (RM) has been proposed to replace the old and sometimes misused term “renal dysplasia” in dogs. Although renal dysplasia has been described in Boxers, hereditary transmission has only been hypothesized. This study reports clinical and renal histological findings in Boxer dogs with RM, proposing a possible mode of inheritance. Medical records of 9 female Boxer dogs, older than 5 months and with a clinical diagnosis of chronic kidney disease prior to one year of age, were retrospectively reviewed. Polyuria and polydipsia (PU/PD), decreased appetite, weight loss, lethargy and weakness were described in all affected dogs. Common laboratory findings were proteinuria, diluted urine, non-regenerative anemia, azotemia, hyperphosphatemia, hypoalbuminemia and hypercholesterolemia. Histopathology of the kidneys revealed the presence of immature glomeruli in all dogs, which is consistent with RM. In 7 related dogs, the pedigree analysis showed that a simple autosomal recessive trait may be a possible mode of inheritance. Renal maldevelopment should be suspected in young Boxer dogs with a history of PU/PD, decreased appetite, weight loss, lethargy, weakness and proteinuria. Due to its possible inheritance, an early diagnosis of RM may allow clinicians to promptly identify other potentially affected dogs among the relatives of the diagnosed case.

Incidence of and mortality from kidney disease in over 600,000 insured Swedish dogs

Kidney disease is an important cause of morbidity and mortality in dogs. Knowledge about the epidemiology of kidney disease in the dog population is valuable and large-scale epidemiological studies are needed. The aim of the present study was to use insurance data to estimate kidney-related morbidity and mortality in the Swedish dog population. Insurance company data from insured dogs during the years 1995-2006 were studied retrospectively. Incidence and mortality were calculated for the whole group of dogs as well as divided by sex and breed. The total number of veterinary care insured dogs was 665,245. The total incidence of kidney disease in this group of dogs was 15.8 (15.3-16.2) cases/10,000 dog-years at risk. The number of dogs in the life insurance was 548,346 and in this group the total kidney-related mortality was 9.7 (9.3-10.2) deaths/10,000 dog-years at risk. The three breeds with the highest incidence of kidney disease were the Bernese mountain dog, miniature schnauzer and boxer. The three breeds with the highest mortality caused by kidney disease were the Bernese mountain dog, Shetland sheepdog and flat-coated retriever. In conclusion, the epidemiological information provided in this study concerning kidney disease in dogs can provide valuable information for future research.

Glomerulopathy and mutations in NPHS1 and KIRREL2 in soft-coated Wheaten Terrier dogs

Dogs of the soft-coated wheaten terrier breed (SCWT) are predisposed to adult-onset, genetically complex, protein-losing nephropathy (average onset age = 6.3 ± 2.0 years). A genome-wide association study using 62 dogs revealed a chromosomal region containing three statistically significant SNPs (p(raw) ≤ 4.13 × 10(-8); p(genome) ≤ 0.005) when comparing DNA samples from affected and geriatric (≥14 years) unaffected SCWTs. Sequencing of candidate genes in the region revealed single nucleotide changes in each of two closely linked genes, NPHS1 and KIRREL2, which encode the slit diaphragm proteins nephrin and Neph3/filtrin, respectively. In humans, mutations in nephrin and decreased expression of Neph3 are associated with podocytopathy and protein-losing nephropathy. The base substitutions change a glycine to arginine in the fibronectin type 3 domain of nephrin and a proline to arginine in a conserved proline-rich region in Neph3. These novel mutations are not described in other species, nor were they found in 550 dogs of 105 other breeds, except in 3 dogs, including an affected Airedale terrier, homozygous for both substitutions. Risk for nephropathy is highest in dogs homozygous for the mutations (OR = 9.06; 95 % CI = 4.24-19.35). This is the first molecular characterization of an inherited podocytopathy in dogs and may serve as a model for continued studies of complex genetic and environmental interactions in glomerular disease.

Familial glomerulonephropathy in the Bullmastiff

Glomerular disease was diagnosed by histopathologic examination in 11 related Bullmastiff dogs, and clinical and laboratory data were collected retrospectively. Four female and seven male dogs between the ages of 2.5 and 11 years were affected. Clinical signs, including lethargy and anorexia, were nonspecific and occurred shortly before death or euthanasia. In five affected dogs serial blood samples were obtained, and dramatically elevated blood urea nitrogen and creatinine levels were demonstrated up to 2.75 years before death. Protein-creatinine ratios were elevated in six of six dogs and were above normal 3.5 years before death in one dog. The kidneys appeared grossly normal to slightly smaller than normal at necropsy. Histologic abnormalities of the kidneys were consistent with chronic glomerulonephropathy with sclerosis. Examination of the pedigrees of related affected dogs yielded evidence supporting an autosomal recessive mode of inheritance.

Renal dysplasia and urinary tract infection in a Bull Mastiff puppy

Renal dysplasia and concurrent pyelonephritis were diagnosed in a 15-week-old female Bull Mastiff which presented with clinical signs compatible with chronic renal failure. Ultrasound examination was consistent with renal dysplasia and clinical pathology supported a diagnosis of chronic renal failure and urinary tract infection. Renal histological examination demonstrated inflammation and scarring with concurrent tubular dysplasia and persisting primitive glomeruli, although the presence of chronic inflammation complicated interpretation. It is uncertain whether renal dysplasia was inherited or due to a urinary tract infection acquired in the neonatal period. Renal dysplasia has not previously been reported in the Bull Mastiff breed.

Creatinine in the Dog: A Review

Creatinine is the analyte most frequently measured in human and veterinary clinical chemistry laboratories as an indirect measure of glomerular filtration rate (GFR). Although creatinine metabolism and the difficulties of creatinine measurement have been reviewed in human medicine, similar reviews are lacking in veterinary medicine. The aim of this review is to summarize information and data about creatinine metabolism, measurement, and diagnostic significance in the dog. Plasma creatinine originates from the degradation of creatine and creatine phosphate, which are present mainly in muscle and in food. Creatinine is cleared by glomerular filtration with negligible renal secretion and extrarenal metabolism, and its clearance is a good estimate of GFR. Plasma and urine creatinine measurements are based on the nonspecific Jaffé reaction or specific enzymatic reactions; lack of assay accuracy precludes proper interlaboratory comparison of results. Preanalytical factors such as age and breed can have an impact on plasma creatinine (P-creatinine) concentration, while many intraindividual factors of variation have little effect. Dehydration and drugs mainly affect P-creatinine concentration in dogs by decreasing GFR. P-creatinine is increased in renal failure, whatever its cause, and correlates with a decrease in GFR according to a curvilinear relationship, such that P-creatinine is insensitive for detecting moderate decreases of GFR or for monitoring progression of GFR in dogs with severely reduced kidney function. Low sensitivity can be obviated by determining endogenous or exogenous clearance rates of creatinine. A technique for determining plasma clearance following IV bolus injection of exogenous creatinine and subsequent serial measurement of P-creatinine does not require urine collection and with additional studies may become an established technique for creatinine clearance in dogs.

Juvenile nephropathy in a boxer, a rottweiler, a collie and an Irish wolfhound

Juvenile nephropathy was diagnosed in a Boxer, a Rottweiler, a Collie and an Irish Wolfhound dog, each presenting with signs compatible with chronic renal failure. The diagnosis in each case was based on the presence of persistence of poorly differentiated tissue (immature glomeruli and/or tubules, persistent mesenchyme) on histopathologic examination. Although juvenile nephropathy has been reported in many breeds of dog, this is the first report of the condition in the Collie and the Irish Wolfhound and only the second description in the Boxer and the Rottweiler. The possibility of an inherited origin of the condition in these four breeds is at present unknown.

Juvenile nephropathy in a Weimaraner dog

A case of juvenile nephropathy in a two-year-old Weimaraner bitch is reported. Although Juvenile nephropathy has been described in several breeds of dogs, this is the first report in a Weimaraner. Clinical aspects, blood analysis, renal pathology and extrarenal changes are described. The renal changes consisted of tubular as well as glomerular lesions, similar to those described in the miniature schnauzer. The main extrarenal lesion was degeneration and necrosis of subendocardial myocytes in the left atrial wall associated with an inflammatory reaction and focal necrotising arteritis.

Congenital renal diseases

Congenital renal diseases of assorted pathologic types occur in dogs and cats. Many of the conditions are known or suspected to be inherited in specific breeds. However, for most of these disorders the causative defect, pathogenesis, and mode of inheritance remain unknown. Congenital renal diseases usually are progressive and they often cause chronic renal failure in affected animals. Presumptive diagnosis usually is based on clinical findings after exclusion of other conditions, but definitive diagnosis generally requires appropriate pathologic studies.

Diagnosis and long-term management of protein-losing glomerulonephropathy. A 5-year case-based approach

Protein-losing glomerulonephropathy can be a challenging disease for veterinarians to manage. This case-based article illustrates long-term management of protein-losing glomerulonephritis in a dog. Prolonged survival of this patient was attributed to early diagnosis and carefully planned therapeutic intervention consisting of dietary protein reduction and modulation of blood pressure with angiotensin converting enzyme inhibition.

Familial nephropathy in Bernese mountain dogs

Between January 1988 and March 1992 nephropathies were frequently diagnosed in Bernese Mountain Dogs. During this period, 20 animals (16 females, four males), ages 2-5 years (average age at time of diagnosis = 3.3 years) presented with clinically renal insufficiency. Morphologic diagnosis of the renal lesions was identical in all cases, i.e., membranoproliferative glomerulonephritis (MPGN) with concomitant interstitial nephritis. Deposits of immunoglobulin-M (IgM) and of the third complement component were regularly demonstrated immunohistochemically in the glomeruli; deposits of immunoglobulin-A (IgA) and immunoglobulin-G (IgG) were found only in isolated cases. Reduplication of glomerular basement membranes, mesangial interposition, and subendothelial deposits of the immunocomplex type were also detected by electron microscopy. A pedigree analysis indicated that the MPGN in these 20 Bernese Mountain Dogs of approximately the same age was of hereditary genesis. Thus, MPGN should be allocated to the group of familial nephropathies. Serologically, high IgG titers against Borrelia burgdorferi were found in 17 dogs. These findings are discussed in relation to familial nephropathies in humans.

Chronic renal disease in bull terriers

Chronic renal failure was diagnosed in 15 Bull terrier dogs. The dogs ranged in age from one to 8 years. History and clinical findings typically included lethargy, anorexia, polyuria, polydipsia and weight loss. Affected dogs were azotaemic, had elevated serum phosphate and cholesterol, and proteinuria was apparent in all dogs tested (13/13). The concentration of urine was consistently in the nil to minimally concentrated range (specific gravities 1.011-1.017). In those dogs necropsied, both kidneys were approximately two-thirds normal size, tough in consistency, with a pale cortex and a finely nodular capsular surface. Histologically, there was marked nephron loss, diffuse interstitial fibrosis and focal dense radial fibrosis which was especially evident in the renal medulla. Tubular dilation was widespread with focal mineralisation of tubular epithelium and adjacent basement membranes. Glomeruli were often shrunken and segmentally fibrotic. Some Bowman's spaces were extremely dilated. Many less severely affected glomeruli had thickened basement membranes.

Familial progressive nephropathy in young Bull Terriers

The clinical, clinicopathological and pathological findings are described in three Bull Terrier bitches with advanced renal disease. The bitches were less than four years old and showed variable presenting signs but anorexia, lethargy and polydipsia were the most frequent. All three dogs were azotaemic and isosthenuric. Urinary protein was measured in two of the three cases. Both were proteinuric. At necropsy all dogs had shrunken kidneys. Histological examination revealed nephron loss, atrophy of glomerular tufts, interstitial fibrosis, and mineralisation of basement membranes. The progressive renal disease in these dogs was similar to the condition reported in Bull Terriers in Australia, and is probably familial and inherited.

Microscopic features of canine renal dysplasia

Forty-five cases of renal dysplasia in dogs are examined. Microscopic lesions of dysplasia include asynchronous differentiation of nephrons, persistent mesenchyme, persistent metanephric ducts, atypical tubular epithelium, and dysontogenic metaplasia. These may be distinguished from secondary lesions including compensatory hypertrophy and hyperplasia of the nephron and a variety of degenerative and inflammatory lesions. Although morphological features of renal dysplasia in dogs differ somewhat from those in man, microscopic criteria used in the diagnosis of human dysplasia may be useful when applied to the dog.

Comparative pathology of canine hereditary nephropathies: an interpretive review

Hereditary nephropathies in dogs represent multiple complex clinicopathological entities which cause renal failure in juvenile, adolescent, and young adult dogs. To date, nephropathies believed to have a genetic basis have been described in 11 breeds. These disorders represent a variety of developmental, degenerative, and metabolic defects. Many canine hereditary nephropathies are analogous to childhood nephropathies in man. Review of the veterinary literature, comparative pathology, and avenues of future research are discussed.