Evaluation of hepatic contrast enhancement with a hepatocyte-specific magnetic resonance imaging contrast agent (gadoxetic acid) in healthy dogs.

OBJECTIVE: To determine, by means of MRI, the time to maximal contrast enhancement in T1-weighted images following IV administration of gadoxetic acid in healthy dogs and assess the impact of gadoxetic acid on the signal intensity of T2-weighted images. ANIMALS: 7 healthy dogs. PROCEDURES: No hepatic abnormalities were detected during ultrasonographic examination. Each dog was anesthetized and positioned in dorsal recumbency for MRI. Transverse T1- and T2-weighted images of the liver were acquired prior to and following (at 5-minute intervals) IV injection of 0.1 mL of gadoxetic acid/kg. Signal intensity of the liver parenchyma was measured in 3 regions of interest in the T1- and T2-weighted images before and at various times point after contrast agent administration. Time versus signal-to-noise ratio curves were plotted to determine time to maximal contrast enhancement and contrast agent-related changes in signal intensity in T2-weighted images. RESULTS: Analysis of T1-weighted images revealed that mean ± SD time to maximal enhancement after gadoxetic acid injection was 10.5 ± 3.99 minutes. Signal intensity of T2-weighted images was not significantly affected by gadoxetic acid administration. No injection-related adverse effects were observed in any dog. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that gadoxetic acid can be used for hepatic MRI in healthy dogs and the resultant hepatic enhancement patterns are similar to those described for humans. Maximal contrast enhancement occurred between 10 and 15 minutes after contrast agent injection; thus, T2-weighted images may be obtained in the interval between injection and maximal enhancement for a more time-efficient clinical protocol.

Isolation of Tritrichomonas foetus from cats sampled at a cat clinic, cat shows and a humane society in southern Ontario.

Tritrichomonas foetus is a protozoan parasite that has been associated with chronic diarrhea in cats. This study aimed to determine (i) the prevalence of T foetus shedding in cats from three different populations in southern Ontario, and (ii) associations between the presence of T foetus and potential cat management, health and demographic risk factors. A cross-sectional study was conducted involving 140 cats from a cat clinic in Guelph, 46 cats from a humane society in Guelph and 55 cats from two cat shows. Risk factor information was assessed through a questionnaire. The InPouch TF (feline) culture method was used to determine the presence of T foetus in all samples. Polymerase chain reaction was conducted on all samples positive by the InPouch TF, as well as 132 negative samples. The assays were interpreted in series and the prevalence of T foetus shedding and 95% confidence intervals (CI) were estimated at 0.7% (95% CI: 0.0-3.9%; n = 140) from the cat clinic, 0% (95% CI: 0.0-7.7%; n = 46) from the humane society and 23.6% (95% CI: 13.2-37.0%; n = 55) from the cat shows. 'Attendance at cat shows' was the only variable significant in both the univariable and multivariable analyses (P <0.05). No significant association was found between the presence of T foetus and diarrhea at the time of sampling or having a history of diarrhea in the past 6 months. The prevalence of T foetus was highly variable among populations of cats in southern Ontario, with shedding being most common in show cats.

Comparison of citrated native and kaolin-activated samples for thrombelastographic analysis in healthy dogs.

BACKGROUND: Thrombelastographic (TEG) analysis is a test of global hemostasis in veterinary medicine; however, there have been limited comparisons of analysis of citrated native and kaolin-activated samples. OBJECTIVES: The purpose of this study was to determine the variation in TEG variables between citrated native and kaolin-activated whole blood samples and to establish reference intervals for both sample types. METHODS: Citrated whole blood samples were obtained from 40 healthy dogs. Thirty minutes after collection, TEG analysis was performed simultaneously on samples with and without kaolin-activation. Reaction time (R), clotting time (K), angle (α), maximum amplitude (MA), global clot strength (G), and clot lysis at 30 minutes (LY30) were recorded, and the concordance correlation coefficient (ρ(c)) was calculated for each sample type. RESULTS: Significant differences between results obtained for kaolin-activated and native samples were obtained for R (mean difference -1.3 minute, P = .0009), K (-0.7 minute, P = .0003), α (+5.1º, P = .002), MA (+2.4 mm, P = .002), and G (+568 dyn/cm(2), P = .0009). LY30 was not different between methods. There was substantial agreement between methods for G (ρ(c) = .69) and MA (ρ(c) = .65), moderate agreement for R (ρ(c) = .45) and α (ρ(c) = .44), fair agreement for K (ρ(c) = .29), and slight agreement for LY30 (ρ(c) = .04). CONCLUSIONS: The TEG variables were significantly altered by kaolin activation; however, some agreement between sample types suggests a consistent bias. In citrated whole blood activated with kaolin, clot formation time is shortened and the amplitude of the tracing is increased, resulting in a TEG tracing that appears to indicate relative hypercoagulability compared with that obtained using native citrated whole blood samples.

Detection and characterization of Clostridium perfringens in the feces of healthy and diarrheic dogs.

Clostridium perfringens has been implicated as a cause of diarrhea in dogs. The objectives of this study were to compare 2 culture methods and to evaluate a multiplex polymerase chain reaction (PCR) assay to detect C. perfringens toxin genes alpha (α), beta (ß ), beta 2 (ß2), epsilon (ɛ), iota (ι), and C. perfringens enterotoxin (cpe) from canine isolates. Fecal samples were collected from clinically normal non-diarrheic (ND) dogs, (n = 105) and diarrheic dogs (DD, n = 54). Clostridium perfringens was isolated by directly inoculating stool onto 5% sheep blood agar (SBA) and enrichment in brain-heart infusion (BHI) broth, followed by inoculation onto SBA. Isolates were tested by multiplex PCR for the presence of α, ß, ß2, ɛ, ι, and cpe genes. C. perfringens was isolated from 84% of ND samples using direct culture and from 87.6% with enrichment (P = 0.79). In the DD group, corresponding isolation rates were 90.7% and 93.8% (P = 0.65). All isolates possessed the α toxin gene. Beta (ß), ß2, ɛ, ι, and cpe toxin genes were identified in 4.5%, 1.1%, 3.4%, 1.1%, and 14.8% of ND isolates, respectively. In the DD group, ß and ß2 were identified in 5%, ɛ and ι were not identified, and the cpe gene was identified in 16.9% of isolates. Enrichment with BHI broth did not significantly increase the yield of C. perfringens, but it did increase the time and cost of the procedure. C. perfringens toxin genes were present in equal proportions in both the ND and DD groups (P ≤ 0.15 to 0.6). Within the parameters of this study, culture of C. perfringens and PCR for toxin genes is of limited diagnostic usefulness due to its high prevalence in normal dogs and the lack of apparent difference in the distribution of toxin genes between normal and diarrheic dogs.

Independent and combined effects of prednisone and acetylsalicylic acid on thromboelastography variables in healthy dogs.

OBJECTIVE: To describe the effects of prednisone and acetylsalicylic acid (ASA) on results of thromboelastography in healthy dogs. ANIMALS: 16 male mixed-breed dogs. PROCEDURES: Dogs were randomly assigned to 3 treatment groups (4 dogs/group) that received prednisone (median dose, 2.07 mg/kg), ASA (median dose, 0.51 mg/kg), or both drugs, PO, every 24 hours from days 0 through 6. Another group received no treatment (control dogs; n = 4). Thromboelastography variables (reaction time, clotting time, α-angle, maximum amplitude [MA], global clot strength, coagulation index, and percentage of clot lysis at 60 minutes [CL(60)]) were evaluated in blood samples collected (prior to drug administration in treated dogs) on days 0 (baseline), 2, 4, and 6. RESULTS: Administration of ASA alone did not alter TEG variables. For treatment effect, mean global clot strength was increased in the prednisone and drug combination groups, compared with values for control dogs; MA was also increased in the prednisone and drug combination groups, compared with that of controls. For treatment-by-time effect, median CL(60) was increased in the prednisone group on day 6, compared with baseline value in the same dogs and with median CL(60) of the control group on day 6. Median CL(60) was also increased in the drug combination group on day 6, compared with the baseline value and with that of the control group on day 6. CONCLUSIONS AND CLINICAL RELEVANCE: Prednisone administered at approximately 2 mg/kg/d, PO, for 7 days with or without concurrently administered ASA increased clot strength and decreased clot lysis in healthy dogs.

Multiple endocrine diseases in dogs: 35 cases (1996-2009).

OBJECTIVE: To characterize a population of dogs from a tertiary care center with 2 or more endocrine disorders, including the specific disorders and time intervals between diagnosis of each disorder. DESIGN: Retrospective case series. ANIMALS: 35 dogs with 2 or more endocrine disorders. PROCEDURES: Medical records were reviewed, and the following was recorded: clinical signs, physical examination findings, and the results of CBC, serum biochemical analysis, urinalysis, aerobic bacterial culture of urine samples, endocrine testing, diagnostic imaging, and necropsy. RESULTS: 35 dogs with more than 1 endocrine disorder were identified. Seventy-seven percent (27/35) of the dogs were male, and the mean age at the time of diagnosis of the first endocrinopathy was 7.9 years. Miniature Schnauzer was the most common breed. Twenty-eight of 35 (80%) dogs had 2 disorders; 7 (20%) had 3 disorders. The most common combinations of disorders included diabetes mellitus and hyperadrenocorticism in 57.1 % (20/35) of dogs; hypoadrenocorticism and hypothyroidism in 22.9% (8/35) of dogs; and diabetes mellitus and hypothyroidism in 28.6% (10/35) of dogs. A mean of 14.5 months elapsed between diagnosis of the first and second endocrine disorders, whereas there was a mean of 31.1 months between diagnosis of the first and third endocrine disorders. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that the occurrence of multiple endocrine disorders was uncommon in dogs. The most common combinations of endocrine disorders in this population of dogs were diabetes mellitus and hyperadrenocorticism, followed by hypoadrenocorticism and hypothyroidism.

Migration of cells from the yolk sac to hematopoietic tissues after in utero transplantation of early and mid gestation canine fetuses.

BACKGROUND: In utero hematopoietic cell transplantation offers a means of early intervention for the treatment of diseases before birth. Delivery of cells to the yolk sac is a minimally invasive approach that results in low levels of chimerism. However, there is little information on the optimal doses, timing of delivery, and migration of transplanted cells from the yolk sac into the fetus. METHODS: Varying cell doses of mesenchymal stromal cells or bone marrow mononuclear cells labeled with fluorescent supraparamagnetic iron oxide nanoparticles and a fluorescent intracellular dye, 5- and 6-([(4-chloromethyl)benzoyl]-amino) tetramethylrhodamine, were transplanted under ultrasound guidance to the yolk sacs of day 25 or day 35 canine fetuses. Ex vivo whole body fluorescence imaging and microscopy of tissue sections were correlated with the presence of iron oxide in injected and control fetuses. RESULTS: Day 25 and day 35 recipients showed similar survival rates after injection of cells into yolk sacs, although increased fetal morality was associated with cell doses greater than 10 cells/kg to day 25 fetuses. The fluorescence and iron oxide signals were predominantly localized to the abdominal regions, with no fluorescence visible in yolk sacs. Microscopy of tissues revealed colocalization of fluorophore with iron oxide in donor cells detected in the fetal livers and bone marrow of recipients 7 and 17 days after receiving mesenchymal stromal cells or bone marrow mononuclear cells. CONCLUSIONS: These studies demonstrated that cells injected into the yolk sacs of early gestation canine fetuses migrate to recipient hematopoietic tissues. Thus, yolk sac injection offers a safe and effective approach for engraftment of cells to fetal hematopoietic tissues.

Multiple endocrine diseases in cats: 15 cases (1997-2008).

The objective of this retrospective study was to characterize a population of cats from a tertiary care center diagnosed with multiple endocrine disorders, including the specific disorders and time intervals between diagnosis of each disorder. Medical records of 15 cats diagnosed with more than one endocrine disorder were reviewed. The majority of cats were domestic shorthairs, and the mean age at the time of diagnosis of the first disorder was 10.3 years. The most common combination of disorders was diabetes mellitus and hyperthyroidism. Two cats had concurrent diabetes mellitus and hyperadrenocorticism, one cat had concurrent central diabetes insipidus and diabetes mellitus. A mean of 25.7 months elapsed between diagnoses of the first and second endocrine disorder, but this was variable. This study suggests the occurrence of multiple endocrine disorders is uncommon in cats.

Effects of lithium carbonate on carboplatin-induced thrombocytopenia in dogs.

OBJECTIVE: To describe the effects of lithium carbonate on thrombopoiesis in clinically normal dogs and in dogs treated with carboplatin. ANIMALS: 18 young adult sexually intact female Beagles. PROCEDURES: Dogs were assigned to each of 3 treatment groups (6 dogs/group). Group 1 received 150 mg of lithium carbonate (14 to 16 mg/kg), PO, every 12 hours on days 1 through 21. Group 2 received carboplatin (300 mg/m(2), IV) on day 0 and cephalexin (30 mg/kg, PO, q 12 h) on days 14 through 21. Group 3 received lithium, carboplatin, and cephalexin at the aforementioned doses and schedules. Plasma lithium and blood platelet concentrations were measured on days 0, 2, 4, 7, 9, 11, 14, 16, 18, and 21. Number of megakaryocytes in bone marrow specimens and the percentage of large unstained cells and CD34+ mononuclear cells in bone marrow aspirates were determined on days 0, 7, 14, and 21 by manual enumeration, automated hematologic analysis, and flow cytometric immunophenotyping, respectively. RESULTS: Plasma lithium concentrations ranged from 0.12 to 2.41 mmol/L. All dogs given lithium achieved a concentration within the target interval of 0.5 to 1.5 mmol/L by days 4 to 7. Thrombopoiesis was increased in dogs receiving lithium alone. All dogs given carboplatin developed mild thrombocytopenia. There were no differences between group 2 and group 3 throughout the study. CONCLUSIONS AND CLINICAL RELEVANCE: Lithium stimulated thrombopoiesis in clinically normal dogs. Lithium administration at the doses and schedules used, with concurrent administration of cephalexin, did not prevent thrombocytopenia induced by carboplatin.

Invasive cutaneous angiomatosis and thrombocytopenia in a cat.

CASE DESCRIPTION: A 9-year-old 6.9-kg (15.18-lb) castrated male Siamese cat was evaluated because of a 3-year history of repeated hemorrhage from the right metacarpal pad. CLINICAL FINDINGS: Physical examination findings were unremarkable except for a 2-mm-diameter erosion of the right metacarpal pad. A CBC revealed marked thrombocytopenia. Serum biochemical analyses, retroviral screening, thoracic radiography, and abdominal ultrasonography revealed no abnormalities. Via ultrasonographic examination, the vasculature in the right metacarpal pad appeared increased, compared with that of the left pad; an aberrant arterial plexus that was confined to the metacarpal pad was identified via arterial angiography. TREATMENT AND OUTCOME: Surgical resection of the metacarpal pad (without digital pad transposition) with primary closure was performed. Histologic evaluation of the pad tissue revealed invasive cutaneous angiomatosis. The incision healed without complications, and limb function was considered normal. Administration of prednisone (2 mg/kg [0.91 mg/lb], PO, q 24 h) was initiated 4 weeks prior to surgery to treat suspected immune-mediated thrombocytopenia and continued afterwards with a tapering dosage. Platelet count was within reference limits 4 months after surgery; at 12 months, there was no evidence of recurrence of abnormal vasculature in the right metacarpal pad region. CLINICAL RELEVANCE: Complete resection of the metacarpal pad (without pad transposition) resulted in successful and well-tolerated treatment of cutaneous angiomatosis of the metacarpal pad of a cat. Recurrence of abnormal vasculature was not evident at a 12-month follow-up examination. Thrombocytopenia is commonly associated with vascular anomalies in humans and may have been a contributing factor in this cat.

Derivation and characterization of canine embryonic stem cell lines with in vitro and in vivo differentiation potential.

Embryonic stem cells (ESCs) represent permanent cell lines that can be maintained in an undifferentiated state. In an environment that induces differentiation, they form derivatives of the three embryonic germ layers: mesoderm, ectoderm, and endoderm. These characteristics give ESCs great potential for both basic research and clinical applications in the areas of regenerative medicine and tissue engineering. The establishment of ESCs from large animals that model human diseases is of significant importance. We describe the derivation of permanent canine cell lines from preimplantation-stage embryos. Similar to human ESCs, canine ESCs expressed OCT3/4, NANOG, SOX2, SSEA-3, SSEA-4, TRA-1-60, TRA-1-81, and alkaline phosphatase, whereas they expressed very low levels of SSEA-1. They maintained a normal karyotype and morphology typical of undifferentiated ESCs after multiple in vitro passages and rounds of cryopreservation. Plating cells in the absence of a feeder layer, either in attachment or suspension culture, resulted in the formation of embryoid bodies and their differentiation to multiple cell types. In vivo, canine ESCs gave rise to teratomas comprising cell types of all three embryonic germ layers. These cells represent the first pluripotent canine ESC lines with both in vitro and in vivo differentiation potential and offer the exciting possibility of testing the efficacy and safety of ESC-based therapies in large animal models of human disease.

PCR ribotyping of Clostridium difficile isolates originating from human and animal sources.

Molecular typing of Clostridium difficile isolates from animals and humans may be useful for evaluation of the possibility for interspecies transmission. The objective of this study was to evaluate C. difficile isolates from domestic animals and humans using PCR ribotyping. Isolates were also tested using PCR for the presence of genes encoding toxins A and B. One hundred and thirty-three isolates of C. difficile from dogs (n = 92), horses (n = 21) and humans (n = 20), plus one each from a cat and a calf, were evaluated. Overall, 23 ribotypes were identified. Of these, nine were identified from dogs, 12 from horses, seven from humans and one each from the cat and calf. In dogs, humans and horses, one or two different ribotypes predominated. Overall, 25 % of isolates from humans were indistinguishable from isolates from one or more animal species. Genes encoding C. difficile toxins A and B were detected in all human, equine and bovine isolates, and in 69 % of canine isolates. While different ribotypes appear to predominate in different mammalian species, several indistinguishable strains may be found in multiple species. This suggests that there is a potential for interspecies transmission of C. difficile and epidemiological studies are warranted.

Endoscopic evaluation of the gastroduodenal mucosa to determine the safety of short-term concurrent administration of meloxicam and dexamethasone in healthy dogs.

OBJECTIVE: To evaluate the safety, with respect to the development of gastric ulcers and erosions, of concurrent administration of meloxicam and dexamethasone for 3 days to healthy dogs. ANIMALS: 20 conditioned purpose-bred research Beagles. PROCEDURE: Seven days prior to treatment, dogs were anesthetized for endoscopic evaluation of the upper portion of the gastrointestinal tract (ie, the gastric and duodenal mucosa). Five regions of the gastroduodenal area were scored by 2 investigators. Dogs were randomly assigned to 1 of 4 treatment groups as follows: saline-saline, dexamethasone-saline, saline-meloxicam, and dexamethasone-meloxicam groups. On days 1, 2, and 3, dogs received either dexamethasone or saline (0.9% NaCl) solution injections SC twice daily. On days 2, 3, and 4, dogs received either meloxicam or saline solution injections SC once daily. On day 2, dogs were anesthetized for a sham surgery (ie, electrostimulation). On day 5, the gastroduodenal area of each dog was reevaluated by use of endoscopic evaluation and histologic examination of biopsy specimens. RESULTS: The total endoscopic score of the dexamethasone-meloxicam group was significantly greater than the scores of the other groups. The dexamethasone-saline group had a mean cumulative score that was significantly greater than the saline-meloxicam or saline-saline groups. Endoscopic scores of the saline-meloxicam group were not significantly different from scores of the saline-saline group. No significant differences in histologic findings were found between groups. CONCLUSIONS AND CLINICAL RELEVANCE: In healthy dogs, meloxicam appears to be safe with regard to adverse effects on the gastrointestinal tract. Concurrent administration of dexamethasone and meloxicam is more likely to cause gastric erosions than meloxicam administration alone.

Delivery of recombinant gene product to canine brain with the use of microencapsulation.

An alternative approach to somatic gene therapy is to deliver a therapeutic protein by implanting "universal" recombinant cells that are immunologically protected from graft rejection with alginate microcapsules. This strategy has proved successful in reversing pathologic conditions in several rodent models of human disease (dwarfism, lysosomal storage disease, hemophilia, cancer). In particular, neurologic disease and behavioral deficit in the mouse model of a neurodegenerative disease (mucopolysaccharidosis [MPS] VII) were significantly improved through the intraventricular implantation of the recombinant encapsulated cells. Here we report the feasibility of delivering recombinant gene products to the central nervous systems (CNSs) of dogs, first using human growth hormone as a marker for delivery in normal dogs and then using alpha-iduronidase as a therapeutic product for delivery in the MPS I dog that is genetically deficient in this lysosomal enzyme. Madin-Darby canine kidney cells were genetically modified to express either human growth hormone or canine alpha-iduronidase, then enclosed in alginate-poly-l-lysine-alginate microcapsules of about 500 microm in diameter. The encapsulated cells were implanted into the brain under steoreotaxic guidance. The brains were monitored with computed tomographic scans before and after surgery and examined biochemically and histologically. Delivery of gene products, as measured in the plasma and cerebrospinal fluid sampled periodically through 21 days or in various regions of the brain after death showed that the delivery of both gene products was extremely low but detectable. However, we noted extensive inflammatory reactions, both at the sites of implantation and in the immediate vicinity of the implanted microcapsules. Hence for this technology to be applicable to the CNSs of larger animals and human beings, a more accurate and less invasive neurosurgical procedure, more biocompatible microcapsule-recombinant cell combinations, and higher output of recombinant products must be developed.