Middle-aged Dogs Research Articles

Signalment differences in bone mineral content and bone mineral density in canine appendicular bones

The objective was to determine signalment-related differences in bone mineral content (BMC) and bone mineral density (BMD) in dogs. Unilateral appendicular bones were harvested from 62 canine cadavers. Mid-diaphyseal regions of interest (ROIs) were scanned using a Hologic DXA device Braincon, Vienna, Austria). BMC and BMD were calculated within this region. Middle-aged dogs (3-10 years) revealed the highest BMC and BMD levels. Mean BMC and BMD were higher in males compared to females. Furthermore, body-weight of the male dogs was significantly higher compared to the females (P < 0.0001). Body weight and bone length were significantly associated with BMC and BMD (P < or = 0.023) in all bones but the radius. These data suggest that BMC and BMD appear to be highest in male large-breed dogs with a body weight greater than 30 kg. These results may help determine risk factors in fracture development and healing.

Risk of anal furunculosis in German Shepherd dogs is associated with the major histocompatibility complex

Anal furunculosis (AF) is a chronic, progressive inflammatory disease of the perianal tissues most frequently affecting middle-aged or older German Shepherd dogs (GSD). Because this breed accounts for over 80% of all reported cases, there is likely to be a genetic association with disease susceptibility. Although there are some similarities with perianal fistulation that occurs in human Crohn's disease, the aetiology and pathogenesis of AF are still poorly understood. Recent research has suggested an immune-mediated aetiology, and evidence for this has been further provided by clinical responses to the immunosuppressive drug cyclosporin. The aim of the current study was to investigate canine major histocompatibility complex immune response genes. Dog leucocyte antigen class II alleles and haplotypes were characterised by sequence-based typing of 107 GSD affected with AF and 196 breed-matched controls collected in the UK. A highly significant association of DLA-DRB1*00101 with the presence of AF was observed (OR = 5.01, CI = 2.7-9.3, P < 0.00000001). This association was confirmed in a second cohort of GSD collected in Finland. Homozygosity for this allele is associated with an earlier disease onset.

Microalbuminuria and Comparison of Serologic Testing for Exposure toBorrelia Burgdorferiin 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.

Combined cytosine arabinoside and prednisone therapy for meningoencephalitis of unknown aetiology in 10 dogs

The differential diagnosis for young to middle-aged dogs with progressive neurological signs, focal or multifocal computed tomography/magnetic resonance imaging lesions, mononuclear cerebrospinal fluid pleocytosis and negative infectious titres includes granulomatous meningoencephalomyelitis, breed-specific meningoencephalitis, infectious meningoencephalitis of unknown origin and central nervous system neoplasia. The terminology meningoencephalitis of unknown aetiology may be preferable for cases that lack histopathological diagnoses. The safety and efficacy of a combination of cytosine arabinoside and prednisone protocol is evaluated, in this study, for the treatment of meningoencephalitis of unknown aetiology in 10 dogs. Cases were selected based on neuroanatomical localisation, negative regional infectious disease titres, cerebrospinal fluid pleocytosis and brain imaging. Clinical response was gauged through follow-up examinations, owner and referring veterinarian surveys and review of medical records. Partial or complete remission was achieved in all dogs; the median survival time for the 10 dogs was 531 days (range 46 to 1025 days), with five of the 10 dogs alive at the time of writing. Prednisone/cytosine arabinoside is a safe empirical therapy for dogs with meningoencephalitis of unknown aetiology; this drug combination may prolong survival time.

A review of the pathophysiology of prostatic diseases

Prostatic disease is common in the middle-aged and older dog. While the majority of clinical cases present as intact male dogs, it must be remembered that neutered animals can also be affected. The clinical signs vary from faecal tenesmus or a preputial discharge through to severe systemic illness, pyrexia and shock. This highlights the need for careful abdominal palpation and rectal examination as part of the clinical assessment in any unwell male dog with non-specific signs of disease. Disorders of the prostate gland are rare in cats.

Influence of the estrous cycle on urodynamic and morphometric measurements of the lower portion of the urogenital tract in dogs

To compare the values of the urodynamic parameters of the lower portion of the urinary tract and vaginourethral measurements obtained during the phases of the estrous cycle in dogs and determine possible functional or anatomic modifications of the lower portion of the urinary tract associated with those phases. 7 adult female Beagles. Urethral pressure profilometry, diuresis cystometry, and vaginourethrography were performed in each dog during proestrus; estrus; early, mid, and late diestrus; and early and late anestrus. The maximum urethral pressure (MUP), maximum urethral closure pressure (MUCP), urethral functional and anatomic profile lengths (UFPL and UAPL, respectively), integrated pressure, threshold pressure, threshold volume, compliance, urethral length, and vaginal length and width were measured. For all measurements, significant interindividual variation was detected. Integrated and threshold pressures, APL, and each morphometric value significantly increased from late anestrus to proestrus. Compared with other phases, MUP, MUCP, and integrated pressure values were significantly lower in estrus and early diestrus; UAPL and UFPL values were significantly lower in late diestrus. At each cycle phase in old dogs, MUP, MUCP, threshold pressure, and vaginal length and width were significantly lower (except in proestrus for vaginal measurements) and threshold volume and compliance values were significantly higher, compared with middle-aged dogs. Urodynamic and morphometric measurements of the lower portion of the urogenital tract are affected by the changes in hormonal balance that occur during the estrous cycle. In sexually intact female dogs, estrous phase determination is important for the interpretation of urodynamic data.

Spontaneous Chronic Corneal Epithelial Defects in Dogs: A Review

Spontaneous chronic corneal epithelial defects (SCCEDs) in dogs are typically found in middle-aged dogs of all breeds. These epithelial defects may be present for weeks to months, particularly if left untreated or if treated inappropriately. Typical histopathological findings include loss of the corneal epithelial basement membrane and formation of a superficial, acellular, hyalinized zone in the stroma. Together, these histological abnormalities lead to delayed wound healing and poor epithelial adhesion. Epithelial debridement, anterior stromal puncture, grid keratotomy, and superficial keratectomy are the most common treatment options applied to the defects. Procedures that address the stromal changes present generally have a higher success rate than epithelial debridement alone.

Establishment of a microplate assay for flow cytometric assessment and it is use for the evaluation of age-related phenotypic changes in canine whole blood leukocytes

The effectiveness of flow cytometric assays for canine use is still requiring standardization. Despite several studies using purified mononuclear cells, no methodology or reference ranges are available for immunophenotyping of whole blood leukocytes (WBL). Fresh and pre-fixed WBL were used to identify cell-subsets, (Thy-1(+)/CD5(+)/CD4(+)/CD8(+)/CD21(+) and CD14(+)) and measure MHC-II, CD45RA/CD45RB expression. We described here an efficient method for fast quantification of canine-WBL, using pre-fix in a microplate assay, which allows long-term sample storage prior to phenotyping. Decreased percentage of CD5(+)-T-cells within the lymphocyte-gate and increased percentage of CD21(+)-B-cells were observed in young animals, which led to higher T/B cell ratios in middle-aged dogs. Lower numerical counts of Thy-1(+), CD4(+), CD8(+) and CD21(+) lymphocyte were observed when compared to young animals. In addition, we identified an age-related decline of MHC-II/CD45RA expression by lymphocytes. We proposed an improved method for phenotyping of canine peripheral blood mononuclear cells (PBMC) that has significant use for researchers and veterinary clinicians. The hematological changes of senescence previously identified on PBMC could be adequately reproduced on features identified by whole blood. Furthermore, this study supplies normal range references as baseline standards for clinical purposes, besides specific immunological parameters to monitor canine aging process.

Degraded cardiomyocytes and dysfunctional energy metabolism; their relationship with canine cardiomyopathies

Tissue sections from hearts of dogs suffering from cardiomyopathies were studied histologically and ultrastructurally. Two types of mitochondrial changes were defined and quantitated. Mitochondrial hypertrophy occurred in cardiomyocytes of middle-aged and older dogs. Significant numbers of degraded cardiomyocytes related to hydropic degeneration of hypertrophied mitochondria associated with autolysis of contractile elements and loss of cellular physiochemical functions were seen in hearts of old dogs with cardiomyopathy. Dogs with cardiac disease that were treated to enhance dysfunctional energy production early in the course of disease had cellular changes similar to those seen in old dogs but they survived heart disease and ultimately died of other causes.

Concept abstraction in the aging dog: development of a protocol using successive discrimination and size concept tasks

The present study examined the effects of age on concept learning in beagle dogs. In experiment one, subjects were tested on a series of 2-choice size discrimination (2CSD) tasks, in which the correct response was to always approach the larger or smaller of the two blocks. Compared to old and senior dogs, young and middle-aged dogs solved the initial training subtest faster and were more successful at transferring this learning to subsequent tests. The second experiment extended the task by using three rather than two objects and introducing novel objects to test concept acquisition. Young and middle-aged dogs made fewer errors than old or senior dogs on a 3-choice size discrimination (3CSD) task. Transfer performance was above chance for all four groups on the 3CSD and first 3-choice size concept (CSC) task and for the young dogs on the second 3CSC but did not differ from the original learning criterion in any group. Age impairments in concept learning may account for differences in transfer performance on both 3CSC tests.

Behavioural Differences of Dogs of Various Ages in Czech Households

Baranyiova E., A. Holub, M. Tyrlik, B. Janaakova, M. Ernstova: Behavioural Differences of Dogs of Various Ages in Czech Households. Acta Vet. Brno 2004, 73: 229-233. The aim of the study was to evaluate the behaviour of dogs of various ages as viewed by their owners in the Czech Republic. The data were obtained in a questionnaire. The dogs were divided by age as follows: 35 animals younger than one year (Y), 220 middle-aged dogs (M), and 12 dogs, seniors (S) older than 8 years (giant and large breed dogs were included in this group at 8 years, medium at 10 years, and small and toy breeds at 12 years of age). The following significant differences were found: young dogs were destructive (household items and gardens), they eliminated in the house more frequently and mounted people. They were fed more than twice a day, and were never described as nervous. Middle-aged dogs were more often than others described as dominant and were given treats. Old dogs were most frequently described as nervous, sometimes difficult to control, and excessively barking, whining and howling. On the other hand, they were more often described as protective of the house and household members, and they were most often walked unleashed. These differences are in agreement with earlier data on the ontogeny of dog behaviour, and show some changes in the co-existence of people and dogs of various ages in Czech households. Importantly, they serve as a basic information about behaviour problems that may be encountered in veterinary practice and show a need for client education programmes and preventive behavioural medicine in the country. Young, middle-aged, old dogs, development, behavioural traits, questionnaire

Fibrocartilaginous embolism in 75 dogs: clinical findings and factors influencing the recovery rate.

The records of 75 dogs with fibrocartilaginous embolism of the spinal cord were evaluated retrospectively. The diagnosis was confirmed histopathologically in 21 dogs (group A) and remained suspected in 54 patients (group B). The two groups were compared. Particular emphasis was placed on the description of physiotherapy procedures, recovery rates and prognostic criteria. Results demonstrated that fibrocartilaginous embolism affected mainly middle-aged, large- or giant-breed dogs. Clinical signs were peracute in onset, non-progressive and often asymmetric. Cerebrospinal fluid analysis was normal in the majority of dogs. Intramedullary swelling was the only abnormality detected on myelograms of these patients. A positive correlation was found between a poor prognosis and the involvement of intumescences, symmetrical clinical signs and decreased deep pain sensation. However, physio/hydrotherapy instituted immediately after the diagnostic work-up seemed to have a major influence on the recovery rate.

The influence of age on the cytology of the liver in healthy dogs.

Liver cytology was evaluated in 28 healthy dogs 1-14 years of age with normal liver structure and function. Smears were stained with May-Grünwald-Giemsa. Hepatocytes had distinct cell borders, and cells did not overlap. Cells with two nuclei and cells with intranuclear crystalloid structures were observed regularly. Cytoplasm contained small numbers of vacuoles characteristic of glycogen and lipid and small amounts of pigment consistent with ceroid or bile. Nuclei were uniform. Small numbers of biliary epithelial cells were seen in most samples. Lymphocytes and neutrophils occurred in small numbers, with lipocytes, mast cells, fibrocytes, mesothelial cells, eosinophils, and Kupffer macrophages seen less frequently. Mean parenchymal cell sizes were significantly greater in older dogs, but no age-related differences were observed in nuclear size. Older dogs also had a significantly increased number of nuclei per cell. There were more neutrophils in young and old dogs than in middle-aged dogs.

Canine serum alkaline phosphatase isoenzymes detected by polyacrylamide gel disk electrophoresis.

Serum alkaline phosphatase (ALP) isoenzymes were studied in normal dogs using a commercially available polyacrylamide gel disk electrophoresis kit (PAG/disk kit). Serum samples taken from the dogs were incubated with neuraminidase, after which most showed ALP isoenzymes as two characteristic stained bands. To determine the origin of each band, ALP isoenzymes of serum and tissue extracts (liver, intestine and bone) were characterized by heating, wheat germ agglutinin (WGA) and levamisole treatments. The results suggested that the band detected on the anode was liver ALP (LALP) and that the band detected on the cathode represented bone ALP (BALP), and both were corticosteroid-induced ALP (CALP). The percentage of each ALP isoenzyme to total ALP activity was estimated by densitometry. The percentage of BALP was the highest in young dogs (age<1 year, 64.7% ), and this value decreased with age. In contrast, the percentage of LALP in young dogs (22.2%) was much lower than that in middle-aged dogs (ages 1 year to 7 years, 59.3%) and old dogs (ages>7 years, 50.4%). The present results suggested that a commercially available PAG/disk kit is capable of detecting three serum ALP isoenzymes in dogs, and further that it may have clinical applications in the evaluation of ALP isoenzymes in veterinary medicine.

Patient and environmental factors associated with calcium oxalate urolithiasis in dogs.

To test the hypothesis that breed, age, sex, body condition, and environment are risk factors for development of calcium oxalate uroliths in dogs. Case-control study. 1,074 dogs that formed calcium oxalate uroliths and 1,724 control dogs that did not have uroliths. A validated multiple-choice questionnaire was designed to collect information from veterinarians and owners within 1 year of the date of urolith detection concerning signalment and environment of the dogs. Univariate and multivariate analyses were performed to calculate odds ratios to assess whether breed, age, sex, body condition, and environment were risk factors for calcium oxalate urolith formation. Middle-aged (8- to 12-year-old) castrated male dogs had increased risk for formation of calcium oxalate uroliths. Urolith formation was also associated with increasing age. Dogs of certain breeds, including Miniature and Standard Schnauzer, Lhasa Apso, Yorkshire Terrier, Bichon Frise, Shih Tzu, and Miniature and Toy Poodle, had increased risk for developing calcium oxalate uroliths. Overweight dogs also had increased risk. Knowledge of patient and environmental risk factors for development of calcium oxalate uroliths may facilitate development of surveillance strategies that result in earlier detection of this disease. Modification of environmental factors and body weight may minimize calcium oxalate urolith formation and recurrence.

Degenerative Lumbosacral Stenosis

This article reviews the management of degenerative lumbosacral stenosis. Degenerative lumbosacral stenosis occurs when soft tissue and bony changes, possibly in conjunction with abnormal motion of the lumbosacral joint, impinge on the nerve roots or vasculature of the cauda equina. It occurs most frequently in middle-aged dogs of medium to large breed, especially the German Shepherd dog. Common signs are lumbosacral pain, lameness, pelvic limb weakness and ataxia, and urinary incontinence. Diagnosis is based on clinical features and imaging studies. Decompressive surgery is effective in most patients.

Effects of intramuscular administration of low doses of medetomidine and medetomidine-butorphanol in middle-aged and old dogs

Objective To determine effects of low doses of medetomidine administered with and without butorphanol and glycopyrrolate to middle-aged and old dogs. Design Prospective randomized clinical trial. Animals 88 healthy dogs ≥ 5 years old. Procedure Dogs were assigned randomly to receive medetomidine (2, 5, or 10 pa/kg [0.9, 2.3, or 4.6 μg/lb] of body weight, IM) alone or with glycopyrrolate (0.01 mg/kg [0.005 mg/Ib], SC), medetomidine (10 μg/kg) and butorphanol (0.2 mg/kg [0.1 mg/lb], IM), or medetomidine (10 μg/kg), butorphanol (0.2 mg/kg), and glycopyrrolate (0.01 mg/kg). Anesthesia was induced with thiopental sodium and maintained with isoflurane. Degree of sedation and analgesia were determined before and after medetomidine administration. Respiratory rate, heart rate, and mean arterial blood pressure were determined 10 and 30 minutes after medetomidine administration. Adverse effects and amounts of thiopental and isoflurane used were recorded. Results Sedation increased after medetomidine administration in 79 of 88 dogs, but decreased in 7 dogs that received 2 or 5 μg of medetomidine/kg. Mean postsedation analgesia score and amounts of thiopental and isoflurane used were less in dogs that received medetomidine and butorphanol, compared with other groups. Respiratory rate, heart rate, and blood pressure were not different among groups. Significantly more adverse effects developed in dogs that did not receive glycopyrrolate. Conclusions and Clinical Relevance Administration of medetomidine (10 μg/kg, IM) and butorphanol (0.2 mg/kg, IM) induced sedation and analgesia and reduced amounts of thiopental and isoflurane required for anesthesia in middle-aged and old dogs. Glycopyrrolate decreased frequency of medetomidine-associated adverse effects. (J Am Vet Med Assoc 1999;215:1116–1120)

Comparison of Optisol-GS and neomycin-polymyxin B-gramicidin ophthalmic solution for corneal storage in the dog.

The objective of the research was to compare the efficacy of Optisol-GS (OGS, Bausch & Lomb Surgical, Irvine, CA, USA) with triple antibiotic ophthalmic solution (neomycin-polymyxin B-gramicidin, NPG; Bausch & Lomb, Tampa, FL, USA) in preserving the viability of corneal endothelial cells. The study subjects were thirty young to middle-aged dogs with no gross corneal pathology that had been euthanized by pentobarbital overdose for reasons unrelated to this project. Corneal tissues were harvested, analyzed, and randomly assigned to treatment groups: one of two media (OGS or NPG), and one of five storage times (1, 7, 14, 21, or 35 days). Six corneas were stored in each medium for each time period. Corneal endothelial cell viability was evaluated pre- and poststorage by vital staining (trypan blue and alizarin red S), and endothelial cell morphology was evaluated with scanning electron microscopy. Storage in NPG caused significant loss (100%) of endothelial cells after all storage times. OGS storage maintained a high level of endothelial cell viability up to 21 days (98.9% +/- 1.3% viability). A significant decrease in percentage viability was also found for OGS-stored corneas between 21 and 35 days, when endothelial cell viability decreased to 61.4% +/- 45.9%. The conclusions are that NPG storage at -20 degrees C is a very poor choice of media for corneal tissue banking if graft clarity is the goal. Storage in Optisol-GS at 4 degrees C for up to 21 days resulted in significantly higher percentages of viable endothelial cells. Optisol-GS storage should facilitate corneal preservation for canine keratoplasty patients.

Visual-discrimination learning ability and β-amyloid accumulation in the dog

Young, middle-aged, and old beagle dogs were tested on several visual-discrimination tasks: reward- and object-approach learning, object discrimination and reversal, long-term retention of a reversal problem, and a size-discrimination task. β-Amyloid accumulation in the entorhinal, prefrontal, parietal, and occipital cortices was quantified using immunohistochemical and imaging techniques at the conclusion of cognitive testing. Middle-aged and old dogs were impaired in size-discrimination learning. In each task, a subset of aged dogs was impaired relative to age-matched peers. β-Amyloid accumulation was age-dependent. However, not all middle-aged and old dogs showed β-amyloid accumulation in the entorhinal cortex. The error scores from dogs tested with a nonpreferred object during visual discrimination learning and from reversal learning were correlated with β-amyloid in the prefrontal but not entorhinal cortex. Size-discrimination and reward and object-approach learning error scores were correlated with β-amyloid accumulation in the entorhinal but not prefrontal cortex. The results of these studies support an association between cognitive test and the location and extent of β-amyloid pathology.

Magnetic resonance imaging of anatomic and vascular characteristics in a canine model of human aging

Dogs exhibit both neuroanatomical and cognitive changes as a function of age that parallel those seen in aging humans. This study describes in vivo changes in neuroanatomical and cerebrovascular characteristics of the canine brain as a function of age in a group of dogs ranging from 4 to 15 years old. Dynamic contrast-enhanced magnetic resonance imaging (MRI) was used to measure the kinetics of contrast agents in the brain. Measures of vascular volume and blood-brain barrier (BBB) permeability were derived from a pharmacokinetic analysis. Cortical atrophy and ventricular enlargement were characteristic features of the aged canine brain. Vascular volume did not vary as a function of age and BBB permeability exhibited a nonsignificant increasing trend with age. However, BBB dysfunction was detected in one middle-aged dog that in addition to having unusually large ventricles, demonstrated an early onset of diffuse senile plaques at postmortem. These findings indicate that BBB dysfunction detected by magnetic resonance imaging may be useful for predicting and potentially diagnosing early pathological conditions.