This study evaluated histologically the tissue responses to and the effects of a customized nano-hydroxyapatite (n-HA) block bone graft on periodontal regeneration in a one-wall periodontal-defect model.
A customized block bone for filling in the standardized periodontal defect was fabricated from prefabricated n-HA powders and a polymeric sponge. Bilateral 4×4×5 mm (buccolingual width×mesiodistal width×depth), one-wall, critical-size intrabony periodontal defects were surgically created at the mandibular second and fourth premolars of five Beagle dogs. In each dog, one defect was filled with block-type HA and the other served as a sham-surgery control. The animals were sacrificed following an 8-week healing interval for clinical and histological evaluations.
Although the sites that received an n-HA block showed minimal bone formation, the n-HA block was maintained within the defect with its original hexahedral shape. In addition, only a limited inflammatory reaction was observed at sites that received an n-HA block, which might have been due to the high stability of the customized block bone.
In the limitation of this study, customized n-HA block could provide a space for periodontal tissue engineering, with minimal inflammation.
Bone substitutes; Guided tissue regeneration; Periodontal disease; Tissue engineering; Tissue scaffolds
Background and aims
Recent literature shows that accelerated Portland cement (APC) is a non-toxic material that may have potential to promote bone healing. The objective of this study was to histologically evaluate periodontal healing focusing on new bone regeneration following implantation of APC into intra-bony defects in dogs.
Materials and methods
Three-wall intra-bony periodontal defects were surgically created at the mesial aspect of the first molar in both sides of mandible in six dogs. One side was randomly filled with the material and other received a flap operation only. The animals were euthanized eight weeks post-surgery when block sections of the defect sites were collected and prepared for qualitative histological analysis.
Compared to control group, stimulation of growth of new bone tissue in the cavity con-taining APC was significantly prominent in three of six cases, showing osteoid formation with osteoblastic rimming and new bone trabeculla. New bone formation was observed just close to cavity containing APC. Connective tissue proliferation and downgrowth of epithelium were signif-icantly less than those of control group.
Our results are encouraging for the use of APC as a bone substitute, but more comprehensive study are necessary before warranting clinical use.
Accelerated Portland cement; bone substitutes; osteogenesis
A survey of the histology of gastric biopsies in 501 dogs, consisting of 19 clinically healthy dogs and 482 vomiting dogs is presented. Whole stomachs of four young clinically healthy laboratory dogs were used as controls. Eleven percent of forceps biopsies were unsuitable for examination; all suction biopsies were of good quality. Slight to severe gastritis was found in 168 vomiting dogs (35%), whereas five dogs (26%) of the clinically healthy group showed a mainly slight gastritis. Superficial and diffuse gastritis were the most prominent findings in the 168 dogs with gastritis. A single type of gastritis was found in 114 dogs, a combination of different types in 54 dogs. Gastric atrophy was seen in 23 (5%) vomiting dogs and in three (15%) clinically healthy dogs, atrophy with a slight to severe fibrosis in 21 (4%) vomiting dogs, and in 84 (17%) vomiting dogs and two (11%) healthy dogs, gastric fibrosis was present. Carcinomas were seen in 26 vomiting dogs, of which 17 also had gastritis. A differential diagnosis of granulomatous gastritis/carcinoma had to be made in one case. Seven dogs showed a lymphosarcoma, and in six other dogs a differential diagnosis of lymphosarcoma and/or gastritis was made. One adenomatous polyp was seen. In one clinically healthy dog an adenomyoma was diagnosed. Ulceration was found in 24 dogs, but only five of these lacked other lesions. Other biopsy findings were pseudopyloric metaplasia, hyperplasia, cysts, calcification and edema. Some dogs showed "antralization".
Addison's disease, also known as hypoadrenocorticism, has been reported in many individual dogs, although some breeds exhibit a greater incidence than the population as a whole. Addison's is presumed to be an autoimmune mediated hereditary defect but the mode of inheritance remains unclear. In particular, the heritability and mode of inheritance have not been defined for the Portuguese Water Dog although Addison's is known to be prevalent in the breed.
The analyses present clear evidence that establishes Addison's disease as an inherited disorder in the Portuguese Water Dog with an estimate of heritability of 0.49 (± 0.16); there were no differences in risk for disease across sexes (p > 0.49). Further, the complex segregation analysis provides suggestive evidence that Addison's disease in the Portuguese Water Dog is inherited under the control of a single, autosomal recessive locus.
The high heritability and mode of inheritance of Addison's disease in the Portuguese Water Dog should enable the detection of segregating markers in a genome-wide scan and the identification of a locus linked to Addison's. Though the confirmation of Addison's disease as an autosomal recessive disorder must wait until the gene is identified, breeders of these dogs may wish to keep the present findings in mind as they plan their breeding programs to select against producing affected dogs.
The aim of this study was to provide a systematic pathological and parasitological overview of the gastrointestinal tract (GIT), including the stomach, duodenum, jejunum, ileum, caecum and colon, of dogs naturally infected with Leishmania.
Twenty mongrel dogs naturally infected with Leishmania (Leishmania) infantum and obtained from the Control Zoonosis Center of the Municipality of Ribeirão das Neves, Belo Horizonte Metropolitan area, Minas Gerais (MG) state, Brazil, were analyzed. The dogs were divided into two groups: Group 1 comprised nine clinically normal dogs and group 2 comprised 11 clinically affected dogs. After necropsy, one sample was collected from each GIT segment, namely the stomach, duodenum, jejunum, ileum, caecum and colon. Furthermore, paraffin-embedded samples were used for histological and parasitological (immunohistochemistry) evaluation and a morphometrical study were carried out to determine the parasite load (immunolabeled amastigote forms of Leishmania). The Friedman and the Mann Whitney tests were used for statistical analysis. The Friedman test was used to analyze each segment of the GIT within each group of dogs and the Mann Whitney test was used to compare the GIT segments between clinically unaffected and affected dogs.
The infected dogs had an increased number of macrophages, plasma cells and lymphocytes, but lesions were generally mild. Parasite distribution in the GIT was evident in all intestinal segments and layers of the intestinal wall (mucosal, muscular and submucosal) irrespective of the clinical status of the dogs. However, the parasite load was statistically higher in the caecum and colon than in other segments of the GIT.
The high parasite burden evident throughout the GIT mucosa with only mild pathological alterations led us to consider whether Leishmania gains an advantage from the intestinal immunoregulatory response (immunological tolerance).
Cardiac arrhythmias, endocarditis, or myocarditis was identified in 12 dogs, of which 11 were seroreactive to Bartonella vinsonii subspecies berkhoffii antigens. Historical abnormalities were highly variable but frequently included substantial weight loss, syncope, collapse, or sudden death. Fever was an infrequently detected abnormality. Cardiac disease was diagnosed following an illness of short duration in most dogs, but a protracted illness of at least 6 months' duration was reported for four dogs. Valvular endocarditis was diagnosed echocardiographically or histologically in eight dogs, two of which also had moderate to severe multifocal myocarditis. Four dogs lacking definitive evidence of endocarditis were included because of seroreactivity to B. vinsonii antigens and uncharacterized heart murmurs and/or arrhythmias. Alpha proteobacteria were not isolated from the blood by either conventional or lysis centrifugation blood culture techniques. Using PCR amplification and DNA sequencing of a portion of the 16S rRNA gene, B. vinsonii was identified in the blood or heart valves of three dogs. DNA sequence alignment of PCR amplicons derived from blood or tissue samples from seven dogs clustered among members of the alpha subdivision of the Proteobacteria and suggested the possibility of involvement of one or more alpha proteobacteria; however, because of the limited quantity of sequence, the genus could not be identified. Serologic or molecular evidence of coinfection with tick-transmitted pathogens, including Ehrlichia canis, Babesia canis, Babesia gibsonii, or spotted fever group rickettsiae, was obtained for seven dogs. We conclude that B. vinsonii subsp. berkhoffii and closely related species of alpha proteobacteria are an important, previously unrecognized cause of arrhythmias, endocarditis, myocarditis, syncope, and sudden death in dogs.
Twenty 6-week-old specific-pathogen-free beagles were infected with Borrelia burgdorferi by tick challenge, and five uninfected dogs served as controls. During the study, all dogs were monitored for infection, clinical signs, and antibody response against B. burgdorferi. During episodes of lameness or postmortem, synovial fluids from each dog were examined for volume, cell number, polymorphonuclear leukocyte (PMN) content, cell viability, and chemotactic activity. Twenty-five tissues collected postmortem from each dog were tested for interleukin-8 (IL-8) mRNA, tumor necrosis factor alpha (TNF-alpha) mRNA, presence of live spirochetes, and histopathological changes. Thirteen infected dogs (group A), which seroconverted rapidly (maximum titers within 50 to 90 days), developed acute and severe mono- or oligoarthritis almost exclusively in the limb closest to the tick bite (median incubation period, 66 days). Synovial fluids of the arthritic joints collected during episodes of lameness had significantly elevated volume, cell count, PMN proportion, cell viability, and chemotactic activity for PMNs. The remaining joints of the same animals contained synovial fluids with elevated chemotactic activity and cell viability. Twelve dogs tested positive for IL-8 mRNA in multiple tissues (synovia, pericardium, and peritoneum), and 10 dogs expressed TNF-alpha mRNA, but only in the tributary lymph nodes of the inflamed joints. Histological examinations revealed severe poly- or oligoarthritis and moderate to severe cortical hyperplasia in draining lymph nodes of the inflamed joints in all 13 dogs. Seven infected dogs with mild or no clinical signs (group B) seroconverted slowly (peak titers after 90 days), and only some joint fluids showed chemotactic activity, which on average was lower than that in inflamed and noninflamed joints from dogs in group A. Four dogs expressed IL-8 mRNA (in the synovia and pericardium), and three dogs had TNF-alpha mRNA in tributary lymph nodes. Histologically, nonsuppurative arthritis was found in multiple joints, and mild to moderate cortical hyperplasia was found in draining lymph nodes. Five uninfected dogs without lameness (group C) had normal synovial fluids and tissues. In all infected dogs, live spirochetes were demonstrated more frequently in tissues of the somatic quadrant closest to the tick bite than in tissues further from the site of infection, suggesting that dissemination of B. burgdorferi occurs more by migration than by blood-borne spread. From these studies employing a canine model of B. burgdorferi infection, we conclude that IL-8 is involved in the pathogenesis of acute Lyme arthritis.
Genetic variation in functionally integrated skeletal traits can be maintained over 10 million years despite bottlenecks and stringent selection. Here, we describe an analysis of the genetic architecture of the canid axial skeleton using populations of the Portuguese Water Dog Canis familiaris) and silver fox (Vulpes vulpes). Twenty-one skeletal metrics taken from radiographs of the forelimbs and hind limbs of the fox and dog were used to construct separate anatomical principal component (PC) matrices of the two species. In both species, 15 of the 21 PCs exhibited significant heritability, ranging from 25% to 70%. The second PC, in both species, represents a trade-off in which limb-bone width is inversely correlated with limb-bone length. PC2 accounts for approximately 15% of the observed skeletal variation, ~30% of the variation in shape. Many of the other significant PCs affect very small amounts of variation (e.g., 0.2–2%) along trade-off axes that partition function between the forelimbs and hind limbs. These PCs represent shape axes in which an increase in size of an element of the forelimb is associated with a decrease in size of an element of the hind limb and vice versa. In most cases, these trade-offs are heritable in both species and genetic loci have been identified in the Portuguese Water Dog for many of these. These PCs, present in both the dog and the fox, include ones that affect lengths of the forelimb versus the hind limb, length of the forefoot versus that of the hind foot, muscle moment (i.e., lever) arms of the forelimb versus hind limb, and cortical thickness of the bones of the forelimb versus hind limb. These inverse relationships suggest that genetic regulation of the axial skeleton results, in part, from the action of genes that influence suites of functionally integrated traits. Their presence in both dogs and foxes suggests that the genes controlling the regulation of these PCs of the forelimb versus hind limb may be found in other tetrapod taxa.
In dogs hip joint laxity that can lead to degenerative joint disease (DJD) is frequent and heritable, providing a genetic model for some aspects of the human disease. We have used Portuguese water dogs (PWDs) to identify Quantitative trait loci (QTLs) that regulate laxity in the hip joint.A population of 286 PWDs, each characterized by ca. 500 molecular genetic markers, was analyzed for subluxation of the hip joint as measured by the Norberg angle, a quantitative radiographic measure of laxity. A significant directed asymmetry was observed, such that greater laxity was observed in the left than the right hip. This asymmetry was not heritable. However, the average Norberg angle was highly heritable as were the Norberg angles of either the right or left hips. After correction for pedigree effects, two QTLs were identified using the metrics of the left and right hips as separate data sets. Both are on canine chromosome 1 (CFA1), separated by about 95 Mb. One QTL, associated with the SSR marker FH2524 was significant for the left, but not the right hip. The other, associated with FH2598, was significant for the right but not the left hip. For both QTLs, some extreme phenotypes were best explained by specific interactions between haplotypes.
quantitative trait loci (QTLs); dog; hip laxity; bilateral asymmetry; Norberg angle; Canine genetics; hip dysplasia
A useful approach for evaluating antitussive drugs in humans is to determine the sensitivity of the cough reflex to a standard challenge. The purpose of this study was to determine if methods used to induce coughing in humans would be effective when used on awake, untrained, healthy dogs for future application in therapeutic trials involving dogs with spontaneous disease. Methods tested were: mechanically stimulating the trachea by digital compression as well as by vibration from an electric shaver, neck massager, and palm sander (11 dogs), and administering nebulized irritant (3000 μM capsaicin), acidic (1 M citric acid), and hypotonic (deionized water) solutions using face masks (4 dogs). The threshold for success was defined as induction of at least 2 moderate or strong coughs in at least 75% of the dogs. None of the methods tested was successful. Digital compression induced soft (n = 2) or moderate (n = 1) coughing in 3 of 11 dogs tested. Nebulization of citric acid induced 1 soft cough in 1 of 4 dogs. It was concluded that coughing cannot be successfully induced in awake, healthy dogs using methods that are successful in humans. Other strategies must be developed so that cough sensitivity can be objectively and non-invasively measured in dogs for clinical research purposes.
Twelve control dogs receiving a single intravenous injection of mercuric chloride, 3.0 mg. per kg., all died within 4 to 11 days afterwards with marked nitrogen retention and extensive necrosis and calcification of the epithelium lining the proximal convoluted tubules. Three dogs of comparable age and weight were reduced to a standard hypoproteinemic state by repeated plasmapheresis. Each dog then received the same dose of mercuric chloride as the controls. None of these dogs became sick, none showed any elevation of non-protein nitrogen, and the kidneys— both in the gross and histologically—appeared normal when they were examined 8 to 45 days later. As tested thus far intensive plasmapheresis following the injection of mercuric chloride has been without effect in preventing the classical changes of mercuric chloride injury observed in the control dogs. The simplest explanation for these phenomena is that mercuric chloride acts on a more or less specific substance (presumably fabricated or concentrated in the renal cortex) which is depleted in the standard hypoproteinemic state. Other possibilities are mentioned. These findings are in sharp contrast to the results of similar experiments with uranium nitrate. The hypoproteinemic state appears to render the animals more susceptible to uranium injury (3). This probably indicates that the mode of action of the two heavy metals is different.
This study examined the functional and morphological changes experienced by bone and muscle during Ilizarov distraction osteogenesis. Although extensive research has been conducted in the area of regenerate bone formation, the effect of limb lengthening on the biomechanical properties of bone and muscle has not been thoroughly addressed. In this study, an Ilizarov external fixator was applied to one tibia of nine skeletally mature dogs, and distracted 3 cm over thirty days. The contralateral tibia served as control. Histology and weekly radiographs assessed muscle morphology and bone growth. The contractile capabilities of the gastrocnemius muscles from the experimental and control limbs were measured prior to sacrifice, and the bending stiffness of the tibias of five dogs was determined. All dogs experienced loss of knee extension secondary to muscle contracture and/or stiffness about the joint. These dogs did not bear weight on the experimental limb. In one dog, spontaneous resolution of the muscle contracture allowed partial weight bearing during the last three weeks of consolidation. Despite 3 cm distraction, tibial lengthening ranged from 1.7 to 3 cm. Biomechanical testing revealed a significant reduction in the bending stiffness of the lengthened bones when compared with control values (p < 0.003). The weight of the lengthened muscles was 35% less than control values, a finding consistent with the histology which showed mild muscle fiber degeneration in all dogs. The contractile capabilities of the lengthened muscles were reduced to 29-80% of control values (p < 0.005). In contrast, the lengthened muscle from the weight bearing dog retained 85% of the weight and 104% of the maximum contractile force of the control muscle.
Establishment of infection with Helicobacter pylori and gastritis in nonhuman species is currently only successful in gnotobiotic piglets. This study was designed to determine whether H. pylori will colonize the gastrointestinal tract of gnotobiotic dogs. Gnotobiotic beagle pups were derived by standard methods. Group A (five dogs) was orally challenged with 3 x 10(8) H. pylori at 7 days of age. Group B (two dogs) received only peptone water but was contact-exposed beginning on day 23 postinfection (p.i.). Necropsy was performed on dogs on day 30 p.i. H. pylori colonized the stomach of all dogs (groups A and B). Urease map analysis correlated with the microbiologic findings and indicated that the density of colonization was less than that observed in human tissue. Organisms were also recovered from the pharynx, esophagus, duodenum, and rectum of 1, 2, 2, and 1 dog, respectively. All group A and one group B dog developed serum immunoglobulin G specific for H. pylori by day 30 p.i. Gross lesions were restricted to the stomach and consisted of small (less than 1 mm) lymphoid follicles. Microscopically, there were focal to diffuse lymphoplasmacytic infiltrates with follicle formation and mild to moderate infiltration of neutrophils and eosinophils in the gastric lamina propria. With the Warthin-Starry silver stain, organisms were seen on the surface of the gastric epithelial cells, beneath the mucus layer. We conclude that H. pylori colonizes the stomachs of gnotobiotic dogs for at least 1 month and the lesions resemble those seen in humans. H. pylori is transmissible by contact from infected to noninfected dogs.
We examined an epileptic focus by electroencephalography (EEG) by using an international 10-20 electrode system in 11 Shetland sheep dogs affected with familial idiopathic epilepsy. We also performed an evaluation of the amino acids in the cerebrospinal fluid (CSF) and a pathologic examination of the brains of 8 dogs that died from status epilepticus. Continuous electroencephalography demonstrated that an epileptic focus was initially detected in the frontal lobe, particularly the internal area, and that paroxysmal foci developed diffusely in other lobes of affected dogs with recurrent convulsions. The EEG analyses indicated spike and sharp wave complexes, which were considered to be paroxysmal discharges. An increased value for glutamate or aspartate was found in the CSF of some epileptic dogs. Histologically, acute neuronal necrosis and astrocytosis were distributed predominantly in the cingulate cortex and internal area of frontal cortex, less frequently in other areas of the cerebrum. The results of this study suggest that, initially, the dogs have an epileptic focus in the frontal lobe, and that the focus extends gradually to other areas of the cerebrum. Based on the distribution of neuronal necrosis and astrocytosis, acute neuronal damage may be related to the superexcitation of neurons following epilepsy.
This report describes the histomorphological changes of central hypothyroidism (pituitary dependent) in several target organs of thyroid hormones of a Portuguese water dog, and contrasts those with the reported features of central hypothyroidism in German shepherd dogs, in which central hypothyroidism is a part of a combined pituitary hormonal deficiency.
A new isolate of canine distemper virus (CDV), named ZJ7, was isolated from lung tissues of a dog suspected with CDV infection using MDCK cells. The ZJ7 isolate induced cytopathogenic effects of syncytia in MDCK cell after six passages. In order to evaluate pathogenesis of ZJ7 strain, three CDV sero-negative dogs were intranasally inoculated with its virus suspension. All infected dogs developed clinical signs of severe bloody diarrhea, conjunctivitis, ocular discharge, nasal discharge and coughing, fever and weight loss at 21 dpi, whereas the mock group infected with DMEM were normal. The results demonstrated that CDV-ZJ7 strain isolated by MDCK cell was virulent, and the nucleotide and amino acid sequences of strain ZJ7 had no change after isolation by MDCK cell when compared with the original virus from the fresh tissues. Molecular and phylogenetic analyses for the nucleocapsid (N), phosphoprotein (P) and receptor binding haemagglutinin (H) gene of the ZJ7 isolate clearly showed it is joins to the Asia 1 group cluster of CDV strains, the predominant genotype in China.
Canine distemper virus (CDV); MDCK; Genotype; Phylogenetic analysis; Pathogenesis; Virulence
Enzyme treatment is the mainstay for management of exocrine pancreatic insufficiency (EPI) in dogs. ‘Enteric-coated’ preparations have been developed to protect the enzyme from degradation in the stomach, but their efficacy has not been critically evaluated. The hypothesis of the current study was that enteric coating would have no effect on the efficacy of pancreatic enzyme treatment for dogs with EPI.
Thirty-eight client-owned dogs with naturally occurring EPI were included in this multicentre, blinded, randomised controlled trial. Dogs received either an enteric-coated enzyme preparation (test treatment) or an identical preparation without the enteric coating (control treatment) over a period of 56 days.
There were no significant differences in either signalment or cobalamin status (where cobalamin deficient or not) between the dogs on the test and control treatments. Body weight and body condition score increased in both groups during the trial (P<0.001) but the magnitude of increase was greater for the test treatment compared with the control treatment (P<0.001). By day 56, mean body weight increase was 17% (95% confidence interval 11-23%) in the test treatment group and 9% (95% confidence interval 4-15%) in the control treatment group. The dose of enzyme required increased over time (P<0.001) but there was no significant difference between treatments at any time point (P=0.225). Clinical disease severity score decreased over time for both groups (P=0.011) and no difference was noted between groups (P=0.869). No significant adverse effects were reported, for either treatment, for the duration of the trial.
Enteric coating a pancreatic enzyme treatment improves response in canine EPI.
Dog; Pancreas; Malabsorption; Diarrhoea; Lipase; Trypsin
Osteoarthritis (OA) is a progressive and debilitating disease that often develops from a focal lesion and may take years to clinically manifest to a complete loss of joint structure and function. Currently, there is not a cure for OA, but early diagnosis and initiation of treatment may dramatically improve the prognosis and quality of life for affected individuals. This study was designed to determine the feasibility of analyzing changes in gene expression of articular cartilage using the Pond-Nuki model two weeks after ACL-transection in dogs, and to characterize the changes observed at this time point.
The ACL of four dogs was completely transected arthroscopically, and the contralateral limb was used as the non-operated control. After two weeks the dogs were euthanatized and tissues harvested from the tibial plateau and femoral condyles of both limbs. Two dogs were used for histologic analysis and Mankin scoring. From the other two dogs the surface of the femoral condyle and tibial plateau were divided into four regions each, and tissues were harvested from each region for biochemical (GAG and HP) and gene expression analysis. Significant changes in gene expression were determined using REST-XL, and Mann-Whitney rank sum test was used to analyze biochemical data. Significance was set at (p < 0.05).
Significant differences were not observed between ACL-X and control limbs for Mankin scores or GAG and HP tissue content. Further, damage to the tissue was not observed grossly by India ink staining. However, significant changes in gene expression were observed between ACL-X and control tissues from each region analyzed, and indicate that a unique regional gene expression profile for impending ACL-X induced joint pathology may be identified in future studies.
The data obtained from this study lend credence to the research approach and model for the characterization of OA, and the identification and validation of future diagnostic modalities. Further, the changes observed in this study may reflect the earliest changes in AC reported during the development of OA, and may signify pathologic changes within a stage of disease that is potentially reversible.
Age-related changes in renal histomorphology are described, while the presence of glomerulonephritis in dogs with pyometra is controversial in current literature.
Dogs with pyometra were examined retrospectively for evidence of secondary renal damage and persisting renal disease through two retrospective studies. In Study 1, light microscopic lesions of renal tissue were graded and compared in nineteen dogs with pyometra and thirteen age-matched control bitches. In Study 2, forty-one owners of dogs with pyometra were interviewed approximately 8 years after surgery for evidence ofclinical signs of renal failure in order to document causes of death/euthanasia.
Interstitial inflammation and tubular atrophy were more pronounced in dogs with pyometra than in the control animals. Glomerular lesions classified as glomerular sclerosis were present in both groups. No unequivocal light microscopic features of glomerulonephritis were observed in bitches in any of the groups.
Two bitches severely proteinuric at the time of surgery had developed end stage renal disease within 3 years. In five of the bitches polyuria persisted after surgery. Most bitches did not show signs of kidney disease at the time of death/euthanasia.
Tubulointerstitial inflammation was observed, but glomerular damage beyond age-related changes could not be demonstrated by light microscopy in the dogs with pyometra. However, severe proteinuria after surgery may predispose to development of renal failure.
The microstructure of the canine colon was described morphometrically. The artifacts induced by administration of enemas and biopsy technique were studied by comparing biopsy specimens to tissues obtained at necropsy from 15 normal dogs. Biopsies from control dogs and clinical cases of colonic disease were then evaluated quantitatively, and histological abnormalities which might clarify mechanisms underlying large bowel dysfunction in the dog were sought. In control dogs, gland length and diameter, epithelial, goblet cell and mucosal mast cell numbers, and intraepithelial lymphocyte and mitotic indices were remarkably uniform throughout the colon. Minor variations were found in the proximal and distal regions of the colon. An apparent shortening of glands, and a reduction in mucous goblets and intraepithelial lymphocytes in biopsies were attributed to suboptimal orientation and irritation caused by enemas. The only significant difference from controls identified by morphometric analysis of biopsies from clinical cases was fewer epithelial cells lining longitudinal sections of glands. It was concluded that failure to identify morphometric variations in the colonic mucosa of clinical cases might reflect either a biased, homogeneously mild clinical syndrome in this group, or the possibility that in many of the clinical cases, a functional rather than physical abnormality was involved. The proprial inflammatory cell population was not examined quantitatively; further investigation of this component is merited.
Reduced bone toughness, the energy absorption capacity of the tissue, has been consistently documented in vertebrae of animals treated with a wide range of bisphosphonate doses. Data regarding toughness changes in the rib are conflicting with one report showing no effect and another showing a significant reduction following treatment of beagle dogs with high doses of bisphosphonates. The goal of this study was to evaluate changes in bone toughness and various other tissue-level properties of the rib following three years of bisphosphonate treatment with doses at and above those used to treat osteoporosis. Skeletally mature intact beagle dogs were treated daily for three years with vehicle (VEH), alendronate 0.2 mg/kg/day (ALN0.2), or alendronate 1.0 mg/kg/day (ALN1.0). The lower ALN dose approximates, on a mg/kg basis, that used for treatment of postmenopausal osteoporosis with the higher dose being 5x higher. Ribs were assessed for biomechanical properties, bone turnover rate, microdamage, density, and geometry. Toughness was significantly lower with ALN1.0 (-33%), but not ALN0.2 (-19%), compared to VEH while neither ultimate stress nor modulus differed among groups. Bone density, geometry, and structural biomechanical properties were similar among the three groups. There was no significant difference in overall microdamage accumulation among groups. Intracortical bone formation rate was significantly lower than VEH in both ALN groups (-69 to -90%). These data show that while rib cortical bone experiences significant reductions in turnover following bisphosphonate treatment, it is only in animals treated with doses above those used to treat osteoporosis that toughness is significantly compromised.
bisphosphonates; remodeling suppression; microcracks; biomechanical properties; cortical bone
A scaling disorder specific to Golden Retriever dogs has been recognized by both dermatologists and pathologists, but to date has not been well characterized. At the University of Pennsylvania’s Laboratory of Toxicology and Pathology, 46 cases of ichthyosis were diagnosed histologically in Golden Retriever dogs from January 2004 to January 2007. A total of 22 dogs had skin lesions documented at younger than 1 year of age; 3 dogs between 1 and 2 years of age; 13 dogs developed lesions at older than 2 years; and the time of onset was unknown for 8 dogs. A total of 25 dogs were female, and 21 were male. All dogs had strikingly similar histopathologic changes that consisted of mild to moderate laminar orthokeratotic hyperkeratosis with an absence of epidermal hyperplasia and dermal inflammation. Ultrastructural analysis using a ruthenium tetroxide fixation method was performed on punch biopsy samples from 5 dogs and compared with 2 control dogs (1 clinically and histologically normal sibling of an affected dog and 1 Cairn Terrier). All affected dogs had retained and convoluted membranes with crystalline structures in the stratum corneum. Scattered keratinocytes in the granular cell layer had prominent, clear, membrane-bound, cytoplasmic vacuoles. Pedigree analysis of 14 dogs was compatible with autosomal recessive inheritance, but incomplete dominance could not be ruled out. This unique hyperkeratotic/scaling disorder in Golden Retrievers has distinctive clinical, histologic, and ultrastructural features, which are consistent with a primary cornification defect.
Canine; cornification; Golden Retrievers; hyperkeratosis; ichthyosis
The aim of this study was to elucidate the effect of a bovine hydroxyapatite/collagen (BHC) block in one-wall intrabony periodontal defects in dogs.
A one-wall intrabony periodontal defect (4 mm wide and 5 mm deep) was prepared bilaterally at the mesial side of the mandibular fourth premolar in five beagle dogs. After thorough root planing, block-type BHC (4×5×5 mm) was placed on one side. The contralateral defect area did not receive any material as a sham-surgery control. Histological analysis of the sites was performed after an 8-week healing period.
Two of five samples in the experimental group healed well without dissipation of the graft materials, and histological analysis revealed excellent regeneration of the periodontal tissues. However, most of the grafted materials had been displaced in the other three samples, leaving only a small portion of the graft. The measured parameters exhibited large standard deviations, and the mean values did not differ significantly between the experimental and sham-surgery control sides.
The application of BHC alone-without a barrier membrane-to wide, one-wall intrabony periodontal defects yielded inconsistent results regarding both periodontal regeneration and substantivity of the graft materials. Thus, the use of a barrier membrane for noncontained-type defects is recommended to improve the stability of the grafted material, and to condense it.
Collagen; Guided tissue regeneration; Histology
The question of whether or not the size of an area of myocardial infarction, measured at 1 wk after coronary occlusion, can be influenced by coronary artery reperfusion was examined in dogs. In seven control experiments the anterior descending coronary artery was ligated, while in seven other studies the occlusion was released after 3 hr. In all animals calibrated photographs were used to assess the zone of hypoperfusion and the acutely injured area of epicardial ST segment elevation, as well as the extent of damage at postmortem 1 wk later. In control dogs, the gross infarct size at postmortem averaged 63.8±7.3% of that predicted from the acutely injured zone. However, in reperfused hearts the average gross infarct size at 1 wk was only 10.2±4.4% of that predicted. Transmural specimens were obtained at autopsy for histology and measurement of myocardial creatine phosphokinase (CPK) activity from sites initially used for epicardial electrocardiography. In control animals, there was a direct relationship between the degree of ST segment elevation and the degree of cell necrosis in transmural histologic sections. ST segment elevation also predicted myocardial CPK (international units per milligram protein): log CPK = − 0.0613 ST + 1.17 (r = 0.66, n = 56 sites). In the reperfused animals, log CPK = − 0.166 ST + 1.36 (r = 0.69, n = 46 sites) showing almost complete preservation of CPK activity at 1 wk, sparing being most prominent in the epicardial zone. Similarly, there was a good correlation between myocardial CPK activity and the histological assessment of cell destruction, the degree of cell damage = − 0.152 CPK + 3.86 (r = 0.86; n = 102 sites). Thus, control dogs showed severe myocardial CPK depletion and histologic evidence of extensive cell destruction, whereas animals subjected to coronary artery reperfusion had little CPK depletion and much less evidence of myocardial cell necrosis 1 wk later.
Specific passive immunity against Pseudomonas aeruginosa sepsis was assessed in granulocytopenic dogs. Dogs were infused with either normal or antipseudomonas immune plasma 24 h before pseudomonas challenge. They were challenged intravenously with 10(7) serotype 6 P. aeruginosa during granulocytopenia. Treatment was evaluated by observation of survival periods, febrile responses, type 6 pseudomonas antibody titers, and quantitative cultures of blood and tissues. The results demonstrated that passively immunized dogs did not survive infection. Both normal-plasma and immune-plasma recipients had bacteremia at death, with median values of 980 and 470 pseudomonas per ml of blood, respectively. All dogs had marked febrile responses 24 h after pseudomonas challenge and had high concentrations of pseudomonas in their lung tissue at death, with median values of 10(8) pseudomonas per g of wet tissue weight. After plasma infusion, immune-plasma recipients had high concentrations of anti-pseudomonas antibody, with total antibody titers ranging from 256 to 1,024 and a median value of 1,024. These titers were comparable to titers attained in a previous study from our laboratory using active immunization with pseudomonas lipopolysaccharide vaccine, where the median total anti-pseudomonas antibody titer was 2,048. Actively immunized animals, however, were significantly protected against pseudomonas sepsis and had prolonged survival periods and prevention of bacteremia. The present study demonstrates that circulating type-specific antibody is not solely responsible for the protection afforded to granulocytopenic dogs actively immunized against pseudomonas.