Healthy Adult Beagle Dogs Research Articles

Circadian variations in salivary chromogranin a concentrations during a 24-hour period in dogs

The purpose of this study was to determine if salivary chromogranin a secretion in dogs exhibits a circadian rhythm. Saliva sampling was performed during three different sessions occurring in three nonconsecutive 24-h periods. Sixteen healthy adult beagle dogs (8 males and 8 females) were moved to a sampling room and housed individually in cages. Saliva samples were obtained every 4 h from 12:00 p.m. to 12:00 p.m. the following day. In the interest of habituation, saliva was obtained hourly from each dog 3 h before the experiment was started. Salivary chromogranin A concentrations were measured using an enzyme-linked immunosorbent assay. No circadian rhythm was detected for salivary chromogranin A secretion, and no differences in salivary chromogranin A concentrations measured every 4 h were demonstrated during the 24-h cycle in dogs.

Pleomorphic extra-renal manifestation of the glomerular podocyte marker podocalyxin in tissues of normal beagle dogs

Podocalyxin (PC) was initially identified as a major sialoprotein on the apical surface of glomerular podocytes to perform the filtration barrier function. Later, it was reported to be expressed in endothelial cells, megakaryotes/platelets, and hemangioblasts, the common progenitor cells of the hematopoietic and endothelial cells. Recently, increasing numbers of reports have indicated that PC is not merely a molecule restricted at renal glomerulus, angiogenic or hematopoietic system. To further elucidate the expression pattern and address the possible physiological role of PC in adult mammals, we conducted an extensive study by immunohistochemistry and immunofluorescence staining on various tissues of healthy adult beagle dogs. By combinatory usage of two different anti-podocalyxin antibodies recognizing distinct epitopes in PC, we have demonstrated that (1) PC is expressed in renal tubules, mesothelium, myocardium, striated muscles in tongue, esophagus and extraocular region, myoepithelial cells in esophagus and salivary glands, neurons, and ependyma, etc.; (2) there are at least three forms of PC proteins, depending upon the accessibility of two different PC antibodies, expressed in different organs/systems; and (3) a particular form of PC is distributed in a vesicle-like compartment in certain organs/systems, such as the central nervous system.

Plasma pharmacokinetics of alfaxalone in dogs after an intravenous bolus of Alfaxan-CD RTU

ObjectiveTo determine the pharmacokinetic parameters of alfaxalone in dogs after the intravenous (IV) administration of clinical and supra-clinical doses of a 2-hydroxypropyl-beta-cyclodextrin (HPCD) alfaxalone formulation (Alfaxan-CD RTU). Experimental designProspective two-period crossover design. AnimalsEight (four male and four female) young adult healthy Beagle dogs. MethodsThe steroid anaesthetic alfaxalone was administered IV at two doses in a crossover design (2 and 10 mg kg−1) with a washout period of 21 days. Blood samples were collected before and up to 8 hours after dosing. Plasma concentrations of alfaxalone were assayed using a liquid chromatograph/mass selective detector technique and analyzed to estimate the main pharmacokinetic parameters by noncompartmental analysis. Results were expressed as mean ± SD. ResultsThe mean duration of anaesthesia from endotracheal intubation to extubation was 6.4 ± 2.9 and 26.2 ± 7.5 minutes, for the 2 and 10 mg kg−1 doses, respectively. The plasma clearance of alfaxalone for the 2 and 10 mg kg−1 doses differed statistically at 59.4 ± 12.9 and 52.9 ± 12.8 mL kg−1 minute−1, respectively (p = 0.008) but this difference was deemed clinically unimportant; the harmonic mean plasma terminal half-lives (t1/2) were 24.0 ± 1.9 and 37.4 ± 1.6 minutes respectively. The volume of distribution was between 2 and 3 L kg−1 and did not differ between the two doses. No sex effect was observed. Conclusions and Clinical relevanceAlfaxalone, as an HPCD formulation (Alfaxan-CD RTU) administered in the dog provides rapid and smooth induction of anaesthesia, satisfactory conditions for endotracheal intubation and a short duration of anaesthesia. There was no clinically significant modification of the pharmacokinetic parameters between sexes and between the clinical (2 mg kg−1) and supra-clinical (10 mg kg−1) doses.

Pharmacokinetics and pharmacodynamics of a therapeutic dose of unfractionated heparin (200 U/kg) administered subcutaneously or intravenously to healthy dogs

Heparin treatment has been recommended for dogs in hypercoagulable states such as disseminated intravascular coagulation, however, potential benefits have to be balanced against the bleeding risk if overdosage occurs. A better understanding of the pharmacology of heparin and tests to monitor heparin therapy in dogs may help prevent therapeutic hazards. The purpose of this study was to evaluate the effects of 200 U/kg of sodium unfractionated heparin (UFH) on coagulation times in dogs after intravenous (IV) and subcutaneous (SC) administration and to compare these effects with plasma heparin concentrations assessed by its antifactor Xa (aXa) activity. 200 U/kg of UFH were administered IV and SC to 5 healthy adult Beagle dogs with a washout period of at least 3 days. Activated partial thromboplastin time (APTT), prothrombin time (PT), and plasma aXa activity were determined in serial blood samples. After IV injection, PT remained unchanged except for a slight increase in 1 dog; APTT was not measurable (>60 seconds) for 45-90 minutes, and then decreased gradually to baseline values between 150 and 240 minutes. High plasma heparin concentrations were observed (maximal concentration = 4.64 +/-1.4 aXa U/mL) and decreased according to a slightly concave-convex pattern on a semilogarithmic curve, but returned to baseline slightly more slowly (t240-t300 minutes) than did APTT. After SC administration, APTT was moderately prolonged (by a ratio of 1.55 +/-0.28 APTT t0, range 1.35-2.01) between 1 and 4 hours after administration. Plasma aXa activity reached a maximum of 0.56 +/-0.20 aXa U/mL (range 0.42-0.9 U/mL) after 132 +/-26.8 minutes; this lasted for 102 +/-26.8 minutes. Prolongation of APTTs of 120-160% corresponded to plasma heparin concentrations of 0.3-0.7 aXa U/mL. As in humans, the pharmacokinetics of UFH in dogs was nonlinear. Administration of 200 U/kg of UFH SC in healthy dogs resulted in sustained plasma heparin concentrations in accordance with human recommendations for thrombosis treatment or prevention, without excessively increased bleeding risks. In these conditions, APTT can be used as a surrogate to assess plasma heparin concentrations. These findings need to be confirmed in diseased animals.

Avaliação dietética de amidos pelas respostas glicêmica e insulinêmica em cães

Avaliaram-se, em cães saudáveis, os efeitos da fonte e do tipo de processamento do amido presente no alimento sobre as concentrações de insulina e glicose plasmáticas pós-prandiais. Foram utilizados oito cães da raça Beagle, adultos, alimentados com quatro regimes: amido cru de trigo (ACT), amido gelatinizado de trigo (AGT), amido cru de mandioca (ACM) e amido gelatinizado de mandioca (AGM). As amostras de sangue foram coletadas mediante punção da veia braquial aos 0, 70, 140, 250 e 360 minutos pós-prandiais. O regime não influenciou a glicemia, mas alterou a concentração sangüínea de insulina (P<0,05). Na área total sob a curva insulinêmica, o regime ACT não diferiu do AGM e foi superior aos regimes AGT e ACM, em razão da viscosidade do AGT e da resistência ao ataque enzimático do ACM. Os resultados sugerem que o regime AGT deve ser preferido aos demais por minimizar a resposta insulínica pós-prandial e manter a euglicemia.

A histopathological study of the morphological changes at the apical seat and in the periapical region after irradiation with a pulsed Nd:YAG laser

In this study, the effects of pulsed Nd:YAG laser irradiation on the apical seat and periapical region of instrumented root canals were investigated. One hundred and ninety-two teeth, including incisors and molars (239 root canals), in 18 healthy adult beagle dogs were used. After extirpation of the pulp under anaesthesia, each root canal was shaped up to at least a size 40 K-file, and then laser irradiated using the following parameters: 1 W, 15 pps for 2, 3, and 4 s; 2 W, 15 pps for 2 s. The effectiveness of debris removal and carbonization on the root canal walls immediately laser irradiation were examined and inflammation of the periapical region at 1, 2, and 4 weeks after laser irradiation was examined using light microscopy. Effective debris removal was observed in most cases in the laser-treated groups and was dependent on irradiated energy. Carbonization was observed in the irradiated root canals except at the parameter of 1 W for 2 s. Periapical inflammation was observed at 1 W for 2 s to the same extent as in the control group (P > 0.01). These results suggest that the pulsed Nd:YAG laser is useful for debris removal with no adverse effects immediately after extirpation of the pulp if appropriate parameters are selected.

Assessment of pituitary function after transsphenoidal hypophysectomy in beagle dogs

Pituitary function was assessed in healthy adult beagle dogs before and after hypophysectomy. Anterior pituitary function was tested by use of the combined anterior pituitary (CAP) function test, which consisted of sequential 30-sec intravenous injections of four hypothalamic releasing hormones, in the following order and doses: 1 μg of cortrticotropin-releasing hormone (CRH)/kg, 1 μg of growth hormone-releasing hormone (GHRH)/kg, 10 μg of gonadotropin-releasing hormone (GnRH)/kg, and 10 μg of thyrotropin-releasing hormone (TRH)/kg. Plasma samples were assayed for adrenocorticotropin (ACTH), cortisol, GH, luteinizing hormone (LH), and prolactin (PRL) at multiple times for 120 min after injection. Pars intermedia function was assessed by the α-melanotropin (α-MSH) response to the intravenous injection of the dopamine antagonist haloperidol in a dosage of 0.2 mg/kg. Posterior pituitary function was assessed by the plasma vasopressin (AVP) response to the intravenous infusion of 20% saline. Basal plasma ACTH, cortisol, thyroxine, LH, PRL, and AVP concentrations were significantly lower at 10 wk after hypophysectomy than before hypophysectomy. In the CAP test and the haloperidol test, the peaks for the plasma concentrations of ACTH, cortisol, GH, LH, PRL, and α-MSH occurred within 45 min after injection. At 2 and 10 wk after hypophysectomy, there were no responses of plasma GH, LH, PRL, and α-MSH to stimulation. In four of eight hypophysectomized dogs, there were also no plasma ACTH and cortisol responses, whereas in the other four dogs, plasma ACTH and cortisol responses were significantly attenuated. The basal plasma ACTH and cortisol concentrations were significantly lower in the corticotropic nonresponders than in the responders. Plasma AVP responses were completely abolished by hypophysectomy, although water intake by the dogs was normal. Histopathological examinations at 10 wk after hypophysectomy revealed that adrenocortical atrophy was much more pronounced in the corticotropic nonresponders than in the responders. No residual pituitary tissue was found along the ventral hypothalamic diencephalon. However, in all hypophysectomized dogs that were investigated, islets of pituitary cells were found embedded in fibrous tissue in the sella turcica. A significant positive correlation was found between the number of ACTH-immunopositive cells and the ACTH increment in the CAP test at 10 wk after hypophysectomy. It is concluded that 1) stimulation of the anterior pituitary with multiple hypophysiotropic hormones, stimulation of the pars intermedia with a dopamine antagonist, and stimulation of the neurohypophysis with hypertonic saline do not cause side effects that would prohibit routine use, 2) in the routine stimulation of the anterior pituitary and the pars intermedia, blood sampling can be confined to the first 45 min, 3) the ACTH and cortisol responses to hypophysiotropic stimulation are the most sensitive indicators for residual pituitary function after hypophysectomy, 4) small islets of pituitary cells in the sella turcica, containing corticotropic cells, are the most likely source of the attenuated corticotropic response that may occur after hypophysectomy, and 5) residual AVP release from the hypothalamus after hypophysectomy is sufficient to prevent diabetes insipidus, despite the fact that the AVP response to hypertonic saline infusion is completely abolished.

Demonstration of serum antiplatelet antibodies in experimental acute canine ehrlichiosis

This report presents evidence for the presence of antiplatelet antibodies in sera of dogs experimentally infected with Ehrlichia canis, during the acute phase of the disease. Six healthy adult male beagle dogs were inoculated intravenously with blood from a longstanding infected dog with the Israel strain 611 of E. canis. Thrombocytopenia and concurrent increase in mean platelet volume were the most consistent haematological signs of the disease. The dogs developed an antibody titre to E. canis from Day 15 postinoculation. All dogs were antiplatelet antibody negative before inoculation. Twenty-four days postinoculation with E. canis, when the platelet count was at its lowest, antibodies to platelets were demonstrated, in the sera of five of the six dogs.

Effects of a [Met]-enkephalin analogue ([d-Ala2,N-Me-Phe4,Met-(O)5-ol]-enkephalin) on canine pituitary function

In adult healthy beagle dogs, plasma concentrations of ACTH, cortisol, alpha-MSH, GH, prolactin and arginine vasopressin (AVP) were measured after i.v. administration of [D-Ala2,N-Me-Phe4,Met-(O)5-ol]-enkephalin (DAMME) at doses of 0.1, 0.5, 1, 5 and 10 micrograms/kg body weight. Significant dose-dependent increases occurred for ACTH, cortisol and GH at dose rates of 0.5, 1, 5 and 10 micrograms/kg body weight. Increments in plasma concentrations of prolactin were significant only at 5 and 10 micrograms DAMME/kg, and there was no significant effect on plasma concentrations of alpha-MSH and AVP. Prior i.v. administration of the opiate antagonist naloxone (0.1 mg/kg) attenuated the DAMME (10 micrograms/kg)-stimulated release of ACTH and cortisol. The results demonstrate that the [Met]-enkephalin analogue DAMME stimulates the release of ACTH, cortisol, GH and prolactin in dogs, and that this stimulation is, at least in part, mediated by mu-opioid receptors. The observations for ACTH and cortisol are different from those in man, where DAMME lowers their basal concentrations.

Effects of serum on the shape change response of polymorphonuclear leukocytes in the dog.

The effects of canine serum on the cellular configuration in vitro were studied in polymorphonuclear leukocytes (PMN) from the peripheral blood of clinically healthy adult beagle dogs. PMN rapidly changed their shape from spherical to ruffled, uropod, or polarized within 1 to 5 min after incubation with freshly isolated autologous or allogeneic canine serum at 37°C, as observed in PMN incubated with zymosan-activated serum and casein. The maximal shape change response (approximately 68%) was observed at 5 min after PMN were exposed to 10% serum. The neutrophils changed their shape faster and at a higher percentage than did eosinophils. Furthermore, the heat treatment (56°C for 30 min) of serum did not affect the PMN shape change response. These results indicate that serum has a potent effect on the induction of the PMN shape change response.