Estimation of heritability of atopic dermatitis in Labrador and Golden Retrievers

OBJECTIVE: To estimate the heritability of atopic dermatitis in Golden and Labrador Retrievers. ANIMALS: 429 dogs related to 13 dogs with atopic dermatitis. PROCEDURE: Atopic dermatitis was defined on the basis of the type and frequency of clinical signs recorded in the clinical records, and each dog was classified with atopic dermatitis or probable atopic dermatitis or as nonatopic. By use of data from atopic and nonatopic dogs, regression analyses of parental status on offspring status were performed to estimate heritability. RESULTS: There was no difference in the frequency of atopic dermatitis between sexes or between breeds. There was a marked association between the atopic status of the parent and that of the offspring, particularly for sires. By use of data from 32 litters in which the status of both parents was known and considering only those dogs classified with atopic dermatitis or as nonatopic, the heritability (+/- SE) of atopic dermatitis was estimated to be 0.47 (+/- 0.17). CONCLUSIONS AND CLINICAL RELEVANCE: Atopic dermatitis has a strong genetic component, and breeding of dogs with clinical signs of atopic dermatitis should be discouraged.     

Cartilage canals in the medial coronoid process of young Golden Retrievers

The aim of the study was to establish the location of cartilage canals in the medial coronoid process (MCP) of the ulna of young Golden Retrievers, a breed that is predisposed to fractures of the medial coronoid process (FMCP). To determine whether the presence of cartilage canals could be associated with the predilection site of FMCP, the right elbows of nine young Golden Retrievers (aged 4, 6, 8, 10, 13, 16, 18, 22 and 24 weeks) were dissected and, with no prior decalcification, the formaldehyde-fixed MCPs were embedded in methylmethacrylate. The entire MCPs were serially sectioned in the frontal plane from cranial to caudal and the sections (5 microm) were routinely stained. Between the ages of 5 and 10 weeks, three main cartilage canals were visible--medial, central and lateral. All originated from the periosteum of the distal parts of the MCP and ended proximally under the articular cartilage. Branches of the main canals were seen more cranially and caudally. At the age of 13 weeks, the central canal was absent, and the remaining canals showed a smaller diameter. From 16 weeks onwards, no cartilage canals were seen. No direct relationship could be established between the predilection site of FMCP (lateral part of the MCP) and the presence/absence of cartilage canals, since both medial and lateral canals disappeared at the same age. Further research is needed to elucidate the pathogenesis of FMCP.     

A histopathological study of iridociliary cysts and glaucoma in Golden Retrievers

This is a retrospective histopathological study of archive slides from the Comparative Ocular Pathology Laboratory of Wisconsin from 1981 to 1997. Reports on eyes or ocular contents from 2176 dogs were reviewed. Five-hundred and thirty out of 2176 (24%) of the cases had a clinical or histologic diagnosis of glaucoma. Twenty-five out of 530 (5%) of the canine cases of glaucoma were in Golden Retrievers. Thirteen out of 25 (52%) of the Golden Retriever cases of glaucoma had iridociliary cysts. Iridociliary cysts in Golden Retrievers may lead to the development of glaucoma. Histologically all 13 of the cases of glaucoma and iridociliary cysts had large thin-walled cysts lined with attenuated cuboidal epithelium filling most of the posterior chamber. The following histologic features were also present: thick walled cysts containing hyaluronic acid (8/13; 62%), a solid cellular proliferation (2/13; 15%), a retrocorneal membrane associated with a defect in Descemet's membrane (7/13; 54%), iris bombé (5/13; 38%), a preiridal fibrovascular membrane (4/13; 31%), hemorrhage (4/13; 31%), a cellular membrane on the anterior lens surface (6/13; 46%), retinal detachment (5/13; 38%), peripheral anterior synechia (5/13; 38%), and posterior synechia (6/13; 46%). Complete follow up was obtained on 11/13 (85%) of the Golden Retrievers with glaucoma and iridociliary cysts. Two/11 (18%) of the dogs were euthanized due to intractable glaucoma. Eight/13 (62%) of the dogs had problems in the other eye. The other eye was diagnosed with uveitis 5/11 (45%), glaucoma 2/11(18%), pigment in the anterior chamber 3/11 (27%), and iridociliary cysts 4/11 (36%).     

Neurologic dysfunction in hypothyroid, hyperlipidemic Labrador Retrievers

BACKGROUND: Hypothyroidism has been associated with a variety of neurologic signs, but the mechanism for this association is not completely understood. Hypothyroidism also is associated with hyperlipidemia that predisposes to atherosclerosis, increased blood viscosity, and thromboembolic events. OBJECTIVE: The objective is to characterize neurologic signs potentially associated with hyperlipidemia and atherosclerosis in canine hypothyroidism. ANIMALS: This study used dogs referred to North Carolina State University Veterinary Teaching Hospital for evaluation of neurologic signs. MATERIALS AND METHODS: A retrospective study was conducted in which medical records of dogs with neurologic signs and a diagnosis of hypothyroidism and hyperlipidemia were reviewed. Details of the history, presenting signs, results of routine blood tests, thyroid tests, cerebrospinal fluid (CSF) analysis and diagnostic imaging, and response to therapy were compiled. RESULTS: Three Labrador Retrievers and one Labrador Retriever cross fit the inclusion criteria. All dogs were hypothyroid and severely hyperlipidemic. Neurologic signs included tetraparesis, central and peripheral vestibular signs, facial paralysis, and paraparesis. Two dogs had an acute history and rapid resolution of signs consistent with an infarct, the presence of which was confirmed in 1 of the dogs by magnetic resonance imaging. Two dogs had chronic histories of cranial neuropathies and paraparesis. One of these dogs had evidence of iliac thrombosis and atherosclerosis on ultrasound examination. All dogs improved with thyroid hormone supplementation. CLINICAL RELEVANCE: Labrador Retrievers may be predisposed to the development of severe hyperlipidemia in association with hypothyroidism. One possible consequence of severe hyperlipidemia is the development of neurologic signs due to atherosclerosis and thromboembolic events.     

Phenotypic and genetic evaluation of elbow dysplasia in Dutch Labrador Retrievers, Golden Retrievers, and Bernese Mountain dogs

Canine elbow dysplasia encompasses four developmental diseases: ununited anconeal process, osteochondrosis of the medial part of the humeral condyle, fragmented medial coronoid process (FCP), and incongruity of the elbow joint. Four radiographic views per joint were used to evaluate 2693 Labrador Retrievers (LRs), 1213 Golden Retrievers (GRs), and 974 Bernese Mountain Dogs (BMDs) for the presence of elbow dysplasia between 2002 and 2009 in the Netherlands. The views were also graded for signs of osteoarthritis and sclerosis. FCP was diagnosed most frequently in LRs, GRs and BMDs, with an incidence of 6%, 5%, and 15%, and a heritability of 0.17, 0.24, and 0.06, respectively. Heritabilities were estimated using a sire model and all available ancestors. Sclerosis at the base of the medial coronoid process was the radiographic sign most strongly correlated with FCP (r=0.95, 0.92, and 0.95 in LRs, GRs and BMDs, respectively). The sex of the dog was significantly correlated with the presence of osteoarthritis in LRs, but not in GRs and BMDs. Male LRs were 1.7-fold more frequently, but not more severely, affected by osteoarthritis than female dogs. Age at radiographic examination was significantly associated with osteoarthritis in all three breeds. The heritability estimates in Retrievers were high enough to warrant including FCP findings in the breeding policy, but until the biomechanical and genetic background of elbow dysplasia are better understood, correct phenotyping with a sensitive technique is essential.     

A neurologic syndrome in Golden Retrievers presenting as a sensory ataxic neuropathy

BACKGROUND: A sensory ataxic neuropathy has been observed in Swedish Golden Retrievers recently. ANIMALS: Twenty-one affected Golden Retrievers. METHODS: Clinical and neurologic status, electrophysiologic, and pathologic status as well as pedigree analyses were evaluated. RESULTS: Clinical signs had an insidious onset between 2 and 8 months of age and a slowly progressive course. Affected dogs were ataxic and dysmetric. They had abnormal postural reactions and decreased spinal reflexes but no apparent muscle atrophy. Clinical pathology, radiography, and electrophysiology of motor systems were all within reference values. Sensory nerve conduction results of affected dogs were significantly different from those of a group of control dogs. Necropsy revealed a chronic progressive central and peripheral sensorimotor axonopathy; the proprioceptive pathways were most severely affected. CONCLUSIONS AND CLINICAL IMPORTANCE: This disease in these Golden Retrievers is distinct from other canine breed-related neurodegenerative diseases or hereditary neurodegenerative diseases described in humans. Pedigree analyses indicated a hereditary background, but the mode of inheritance could not be established.     

Evaluation of risk factors for degenerative joint disease associated with hip dysplasia in German Shepherd Dogs, Golden Retrievers, Labrador Retrievers, and Rottweilers.

OBJECTIVE: To determine whether age, breed, sex, weight, or distraction index (DI) was associated with the risk that dogs of 4 common breeds (German Shepherd Dog, Golden Retriever, Labrador Retriever, Rottweiler) would have radiographic evidence of degenerative joint disease (DJD) associated with hip dysplasia. DESIGN: Cross-sectional prevalence study. ANIMALS: 15,742 dogs. PROCEDURE: Hips of dogs were evaluated radiographically by use of the ventrodorsal hip-extended view, the compression v ew, and the distraction view. The ventrodorsal hip-extended view was examined to determine whether dogs had DJD. For each breed, a multiple logistic regression model incorporating age, sex, weight, and DI was created. For each breed, disease-susceptibility curves were produced, using all dogs, regardless of age, and dogs grouped on the basis of age. RESULTS: Weight and DI were significant risk factors for DJD in all breeds. For German Shepherd Dogs, the risk of having DJD was 4.95 times the risk for dogs of the other 3 breeds combined. In all breeds, the probability of having DJD increased with age. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that the probability of having hip DJD increased with hip joint laxity as measured by use of DI. This association was breed-specific, indicating that breed-specific information on disease susceptibility should be incorporated when making breeding decisions and when deciding on possible surgical treatment of hip dysplasia.     

Bartonella DNA in the blood and lymph nodes of Golden Retrievers with lymphoma and in healthy controls

BACKGROUND: Although lymphoma is the most common neoplastic process reported in dogs, its precise etiology is unknown. Golden Retrievers are more likely to develop lymphoma, suggesting a breed predisposition; however, other factors, including environment, immunity, and infection, are likely contributors to oncogenesis. HYPOTHESIS: We hypothesized that the development of lymphoma in Golden Retrievers may be associated with vector-borne infections, specifically Bartonella, Anaplasma, or Ehrlichia species infections. ANIMALS: Golden Retrievers with lymphoma and healthy Golden Retrievers from across the United States were recruited for study participation. METHODS: A matched, case-control study was performed to determine the association of lymphoma and the presence of Bartonella, Anaplasma, and Ehrlichia species in serum, blood, and lymph node aspirates. RESULTS: Using PCR analyses and DNA sequencing, single and coinfections with Bartonella henselae, Bartonella elizabethae, Bartonella quintana, and/or Bartonella vinsonii (berkhoffii) were detected in the blood and lymph node aspirates of Golden Retrievers with lymphoma (5/28 dogs, 18%) and in healthy Golden Retrievers (10/56 dogs, 18%); no Anaplasma or Ehrlichia DNA was detected in any dog. When compared with dogs with lymphoma, a higher (P <.001) proportion of healthy Golden Retrievers were receiving monthly acaricide treatments (2.6 times higher). CONCLUSIONS AND CLINICAL IMPORTANCE: Bartonella DNA can be detected in blood and lymph nodes; importantly, in this report, Bartonella was detected in the same proportion of clinically healthy dogs and dogs with lymphoma. Longitudinal studies should be conducted to determine the mode of transmission of Bartonella in dogs, whether lymphatic infection is persistent, or whether these bacteria may contribute to the development of lymphoma.     

Ultrasonographic evaluation of the thyroid gland in healthy, hypothyroid, and euthyroid Golden Retrievers with nonthyroidal illness

Ultrasound evaluation of the thyroid gland was performed in healthy, hypothyroid, and euthyroid Golden Retriever dogs with nonthyroidal illness (NTI) to determine the diagnostic usefulness of ultrasound for differentiating between euthyroid and hypothyroid dogs. Thirty-six healthy, 11 hypothyroid, and 35 euthyroid dogs with NTI were evaluated. Each thyroid lobe was examined ultrasonographically for size, shape, echogenicity, and homogeneity. Thyroid lobe volume was estimated by using the equation for an ellipsoid: pi/6(length X height x width). No differences were found between healthy dogs and euthyroid dogs with NTI. In the majority of euthyroid dogs, the thyroid lobes were fusiform and triangular in shape in longitudinal and transverse planes, respectively. The thyroid capsule appeared smooth. The thyroid parenchyma had a homogeneous echogenic pattern and usually was hyperechoic or isoechoic compared with the surrounding musculature. Ultrasound findings in hypothyroid dogs were more variable, including a greater frequency of round to oval-shaped thyroid lobes in the transverse imaging plane (P < .05), hypoechogenicity of the thyroid parenchyma compared with surrounding musculature (P < .001), and a decrease in the size and volume of the thyroid lobes and total volume of the thyroid gland (P < .05) compared with euthyroid dogs. Other findings in hypothyroid dogs included an irregular surface to the thyroid capsule, a heterogeneous pattern to the thyroid parenchyma, and differences in the echogenic pattern between the left and right thyroid lobes. Results suggest that determination of thyroid size and volume by ultrasound may be a useful adjunctive test for differentiating between hypothyroid and euthyroid dogs with NTI.     

Microalbuminuria and comparison of serologic testing for exposure to Borrelia burgdorferi in nonclinical Labrador and Golden Retrievers.

Canine Lyme disease is caused by the spirochete Borrelia burgdorferi after transmission by an Ixodes tick, typically resulting in joint pain, fever and lethargy. Lyme nephritis is a poorly characterized syndrome associated with severe glomerular and tubular renal injury and poor clinical outcome in young to middle-aged dogs positive for exposure to B. burgdorferi. The aims of this study were to identify associations between natural exposure to B. burgdorferi and the presence of microalbuminuria in nonclinical young Labrador and Golden Retrievers and to compare two commonly used serologic tests available to document B. burgdorferi exposure: the Western blot and the commercial point-of-care C6 peptide enzyme-linked immunosorbent assay (ELISA) tests. Microalbuminuria was assessed using a commercial point-of-care ELISA specific for canine albumin. Blood and urine samples from 268 asymptomatic Labrador and Golden Retrievers were included. Of these, 18.7% were positive for B. burgdorferi exposure according to the C6 ELISA; 21.2% were positive for natural exposure to B. burgdorferi and 11.5% for vaccinal antibodies according to the Western blot. The agreement rate was 93% between the two tests (kappa = 0.78, P < 0.0001) for natural exposure. Urine from 6.1% of the dogs was positive for microalbuminuria. There was no association between microalbuminuria and exposure to B. burgdorferi based on results of a Western blot (P = 0.57) or C6 ELISA (P = 0.53). Microalbuminuria is likely not a consequence of B. burgdorferi exposure in young nonclinical Labrador and Golden Retrievers.     

Estimates of prevalence of hip dysplasia in Golden Retrievers and Rottweilers and the influence of bias on published prevalence figures

OBJECTIVE: To estimate prevalence of canine hip dysplasia (CHD) in Golden Retrievers and Rottweilers and identify sources of bias in published reports. DESIGN: Prospective study. ANIMALS: 200 clinically normal Golden Retrievers and 140 clinically normal Rottweilers between 24 and 60 months of age referred for hip evaluation (group 1) and 93 clinically normal dogs evaluated for Orthopedic Foundation for Animals (OFA) hip certification (group 2). PROCEDURE: Hip-extended pelvic radiographs from group 1 dogs were screened for CHD. Radiographs were evaluated twice; the first interpretation used an OFA-type subjective 7-point scoring system, and the second included the caudolateral curvilinear osteophyte as an additional sign of degenerative joint disease. The OFA submission rate of group 2 dogs was determined from the number of official reports returned from the OFA. RESULTS: Prevalence of CHD in Golden Retrievers ranged from 53% to 73% and in Rottweilers ranged from 41% to 69%. Among dogs referred for OFA evaluation, radiographs from 49 (53%) were submitted to OFA. Of submitted radiographs, 45 (92%) were normal; of radiographs not submitted, 22 (50%) were normal. Radiographs with normal-appearing hips were 8.2 times as likely to be submitted to the OFA. Compared with Golden Retrievers, Rottweiler radiographs were significantly more likely to be submitted for OFA certification. CONCLUSIONS AND CLINICAL RELEVANCE: Prevalence of CHD in these 2 breeds may be much higher than previously reported in the United States. Results suggest substantial bias in the OFA database, which causes lower estimates of prevalence of CHD.     

Cataracts in Chesapeake Bay Retrievers

Cataracts developed in 13 of 27 related Chesapeake Bay Retrievers. The posterior pole, "Y" sutures, and equatorial cortices of the lens were predominantly affected. In one affected dog, the cataracts had progressed to hypermaturity, permitting restoration of vision. The trait was believed to be dominant, with incomplete penetrance.     

Reliability of goniometry in Labrador Retrievers

OBJECTIVE: To evaluate the reliability of goniometry by comparing goniometric measurements with radiographic measurements and evaluate the effects of sedation on range of joint motion. ANIMALS: 16 healthy adult Labrador Retrievers. PROCEDURE: 3 investigators blindly and independently measured range of motion of the carpus, elbow, shoulder, tarsus, stifle, and hip joints of 16 Labrador Retrievers in triplicate before and after dogs were sedated. Radiographs of all joints in maximal flexion and extension were made during under sedation. Goniometric measurements were compared with radiographic measurements. The influence of sedation and the intra- and intertester variability were evaluated; 95% confidence intervals for all ranges of motion were determined. RESULTS: Results of goniometric and radiographic measurements were not significantly different. Results of measurements made by the 3 investigators were not significantly different. Multiple measurements made by 1 investigator varied from 1 to 6 degrees (median, 3 degrees) depending on the joint. Sedation did not influence the range of motion of the evaluated joints. CONCLUSIONS AND CLINICAL RELEVANCE: Goniometry is a reliable and objective method for determining range of motion of joints in healthy Labrador Retrievers.     

Hereditary nasal parakeratosis in Labrador Retrievers

Hereditary nasal dermatitis is reported in 14 Labrador Retrievers and 4 Labrador Retriever crosses. This appears to be a newly described inherited disorder for which an autosomal recessive mode of inheritance is suspected. The lesions were first noted between 6 and 12 months of age. Histopathological analysis revealed parakeratotic hyperkeratosis, often with marked multifocal accumulation of proteinaceous fluid between keratinocytes within the stratum corneum and superficial stratum spinosum. There was also a sub-basal lymphoplasmacytic infiltration within the superficial dermis. Immunohistochemistry staining for IgG (n = 4), distemper and papillomaviruses (n = 4) were negative, as were serum antinuclear antibody serology (n = 4) and fungal culture (n = 7). Electron microscopy revealed an altered cornification process: retention of nuclear chromatin, absence of lamellar bodies and marked intercellular oedema. Dogs did not respond to oral administration of zinc methionin (n = 3), cephalexin (n = 4), vitamin A alcohol (n = 1) or topical tretinoin (n = 1). Improvement of the lesions was obtained with topical vitamin E (n = 2), petroleum jelly (n = 2), and propylene glycol (n = 5).     

Familial reflex myoclonus in Labrador Retrievers

Three 6-week-old male purebred yellow Labrador Retrievers were presented with intermittent stimulus-sensitive contractions of the appendicular and axial muscles. Five littermates were normal, although the grandsire of the affected litter had sired 2 previous litters containing similarly affected pup. Although alert and responsive, the affected dogs appeared decerebrate with extensor rigidity and opisthotonus during handling. During severe episodes, respiratory distress was observed. Generalized contractions were initiated by voluntary movements, but at rest the muscles relaxed. Neurologic deficits were not detected, although efforts to elicit segmental reflexes, assess muscle tone, or assist walking resulted in generalized stiffness. Electromyograms from the semitendinous muscles (musculi semitendinosus) had increased motor unit amplitude (up to 5,000 microV) with polyphasic action potentials. There were no myotonic discharges. A reduced interference pattern was seen. A single tactile stimuli of the distal limb resulted in 3 responses, each lasting less than or equal to 10 ms at latencies of 0 to 12 ms, 20 to 30 ms, and 35 to 40 ms, characteristic for reflex myoclonus. The motor nerve conduction velocities were normal for age (32 to 35 ms). Age-matched control dogs had motor unit action potentials of 100 to 200 microV and single compound motor unit discharges to single tactile stimuli. Therapeutic trials with diazepam and clonazepam produced minimal effects on the muscle contractions. Values of urinalyses, complete blood cell counts, and serum chemistries were within normal limits. Frozen muscle section biopsy findings, including enzyme histochemical assessment of muscle fiber types, were normal.(ABSTRACT TRUNCATED AT 250 WORDS)