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PubMed1997

Epidemiologic evaluation of the risk factors associated with exposure and seroreactivity to Bartonella vinsonii in dogs.

OBJECTIVES: To determine seroprevalence to Bartonella vinsonii subsp berkhoffii in a population of sick dogs from North Carolina and Virginia and to evaluate potential risk factors associated with increased likelihood of exposure to the organism. SAMPLE POPULATION: Serum samples from 1,920 sick dogs. PROCEDURE: An indirect fluorescent antibody assay was performed on each sample, and the end-point antibody titer was recorded. A case (seropositive) was defined as a dog with reciprocal titer > or = 64, and a control (seronegative) was defined as a dog with reciprocal titer < 16 that was referred within 0 to 3 days of referral of a corresponding case. From this population, 207 dogs (69 cases and 138 controls) were included in a case-control seroepidemiologic study. RESULTS: 3.6% (69/1,920) of the dogs were seropositive to B vinsonii subsp berkhoffii. Results of the case-control study indicated that seropositive dogs were more likely to live in rural environments, frequently on a farm, were free to roam the neighborhood, and were considered to be predominantly outdoor dogs. Moreover, seropositive dogs were 14 times more likely to have a history of heavy tick exposure. After analysis of the case-control study, a more detailed examination of banked sera from dogs with known tick exposure was performed. High correlation was found between sero-reactivity to B vinsonii and seroreactivity to E canis or B canis (36.0 and 57.1%, respectively). Sera derived from dogs experimentally infected with E canis or R rickettsii did not cross react with B vinsonii antigen. CONCLUSIONS AND CLINICAL RELEVANCE: Several potential risk factors are associated with canine exposure to B vinsonii. Rhipicephalus sanguineus, the tick vector for E canis and B canis, may be involved in B vinsonii transmission among dogs.

Animals↗

PubMed1997

Colonic nitrite and immunoglobulin G concentrations in dogs with inflammatory bowel disease.

OBJECTIVE: To evaluate lavage analytes as markers of mucosal inflammation in healthy dogs and dogs with inflammatory bowel disease (IBD). DESIGN: Case control study. ANIMALS: 9 healthy dogs and 10 dogs with IBD. PROCEDURE: A polyethylene glycol electrolyte solution was administered into the dogs colons via a rectal balloon catheter prior to colonoscopy. Lavage solution was allowed to remain intraluminally for 30 minutes and then was withdrawn. Lavage supernatant samples were immediately analyzed for total protein, IgG, and nitrite concentrations and myeloperoxidase activity. Mucosal biopsy specimens were obtained from the descending colon and histologically reviewed. RESULTS: All dogs with IBD had mild to severe lymphocytic-plasmacytic colitis, whereas 8 of 9 healthy dogs did not have substantial mucosal inflammation. Myeloperoxidase activity was not detected in lavage samples from healthy dogs or dogs with IBD. Total protein concentration was not significantly different between groups. Mean nitrite and IgG concentrations were significantly higher in samples from dogs with IBD (1.83 nmol/ml and 46 mg/dl, respectively), compared with samples from healthy dogs (0.245 nmol/ml and undetectable concentrations, respectively). Severity of lesions was not correlated with nitrite or IgG concentration. CLINICAL IMPLICATIONS: Assay of nitrite and IgG concentrations in colonic lavage fluid is a simple, objective means of evaluating mucosal inflammation in dogs with IBD. Potential uses include monitoring response to treatment and evaluation of complex cases of chronic intestinal inflammation.

Analysis of Variance↗

PubMed1998

[Seroepidemiology of Toxoplasma gondii infection among dogs in Taipei, Taiwan].

Seroprevalence of toxoplasmosis in dogs was investigated in Taipei from July 1995 to June 1996 by the latex agglutination assay. A total of 289 serum samples were taken from stray and domestic dogs as well as from dogs in randomly selected animal hospitals and pet stores. The overall seroprevalence among all dogs was 24.6% (71/289). With regard to the source of the dogs, the seropositivity was 15.4% (10/65) for dogs in animal hospitals, 16.3% (7/43) for dogs in pet stores, 15.5% (11/71) for domestic dogs and 39.1% (43/110) for stray dogs. The seropositivity of stray dogs was significantly higher than that of the domestic dogs (P < 0.05). However, there was no significant difference among the randomly selected places or dog strains (P > 0.05).

Animals↗

PubMed1995

Liposome-encapsulated muramyl tripeptide phosphatidylethanolamine adjuvant immunotherapy for splenic hemangiosarcoma in the dog: a randomized multi-institutional clinical trial.

Canine splenic hemangiosarcoma (HSA) is a spontaneous tumor with high metastatic potential. Despite surgical excision, most dogs die within 2 months of diagnosis as a result of widespread visceral metastasis. This study was designed to determine the efficacy of liposome-encapsulated muramyl tripeptide phosphatidylethanolamine (L-MTP-PE) when used in combination with splenectomy and systemic chemotherapy for the treatment of HSA in the dog. Thirty-two dogs with HSA and without gross evidence of metastases were treated with splenectomy, stratified by clinical stage, and randomized to receive doxorubicin/cyclophosphamide chemotherapy and either L-MTP-PE immunotherapy or lipid equivalent (placebo liposomes). Dogs were subsequently followed to determine disease-free survival and overall survival times. The effects of L-MTP-PE on serum tumor necrosis factor-alpha and interleukin 6 activity were assessed on a small subset of dogs. Dogs receiving L-MTP-PE had significantly prolonged disease-free survival (P = 0.037) and overall survival (P = 0.029) compared with dogs receiving placebo. Dogs with clinical stage I disease had significantly prolonged disease-free survival (P = 0. 026) and overall survival (P = 0.017) compared with dogs with clinical stage II disease. Dogs receiving L-MTP-PE had significantly greater serum tumor necrosis factor-alpha (P < 0.001) and interleukin 6 (P = 0.007) activities compared with placebo-treated dogs. L-MTP-PE has significant antimetastatic activity in highly malignant, spontaneously occurring, splenic HSA in the dog. Canine HSA may have potential as a large animal model for additional investigation of antimetastatic chemoimmunotherapy.

Acetylmuramyl-Alanyl-Isoglutamine↗

PubMed2000

Effects of magnesium deficiency on joint cartilage in immature beagle dogs: immunohistochemistry, electron microscopy, and mineral concentrations.

Quinolone-induced chondrotoxicity is possibly associated with the magnesium-chelating properties of quinolones. This toxic effect seems to be restricted to a rather short time period during postnatal development as shown in rats and dogs. We studied developmental changes of the integrin pattern on canine chondrocytes (e.g. the alpha(v)beta(3)- or alpha(5)beta(1)-integrin), because integrin function depends on divalent cations, as well as the matrix composition (e.g., collagen type II, fibronectin), in 11-, 18-, and 55-week-old Beagles (n=8) by immunohistochemistry. We also analyzed the magnesium and calcium content by atomic absorption spectroscopy in cartilage and bone and studied the effects of a magnesium-deficient diet on joint cartilage in four immature Beagles (18 weeks old at necropsy). The dogs were fed the magnesium-deficient diet for 40 to 46 days. All dogs exhibited gait alterations ('limping') after 4 weeks on the magnesium-deficient diet. Male, magnesium-deficient dogs exhibited pronounced weakness in their front legs; in one of these dogs the front legs were hyperextended to a 90 degrees angle. We observed no significant differences in the integrin pattern in samples from dogs at different developmental stages or in magnesium-deficient dogs in comparison to age-matched controls. Localization of fibronectin in the joint cartilage was found to vary with the age of the dogs as well as with the site of collection. In the middle zone of immature joint cartilage, corresponding to the predilective site of quinolone-induced cartilage lesions, we observed a slight increase in staining with the fibronectin antibody in some samples from magnesium-deficient dogs. Electron microscopy revealed alterations in chondrocytes from the magnesium-deficient dogs (e.g., swollen mitochondria and enlarged endoplasmic reticulum) which are also seen after treatment with quinolones. In summary, we found no significant differences of the integrin pattern on chondrocytes from joint cartilage of dogs at various developmental stages. However, magnesium deficiency in immature dogs induced similar clinical symptoms as quinolone treatment as well as distinct alterations in chondrocytic fibronectin staining and their ultrastructure. This corroborates our findings in rats where magnesium chelation is an important event in quinolone-induced chondrotoxicity.

Animals↗

PubMed2005

Sudden cardiac death in dogs with remodeled hearts is associated with larger beat-to-beat variability of repolarization.

Increased proarrhythmia in dogs with chronic AV block (AVB) has been explained by ventricular remodeling causing a decrease in repolarization reserve. Beat-to-beat variability of repolarization (BVR) has been suggested to reflect repolarization reserve, in which high variability represents diminished reserve and larger propensity for repolarization-dependent ventricular arrhythmia. A subset of chronic AVB dogs (10%) suffers sudden cardiac death (SCD). With the assumption that repolarization defects constitute a potentially lethal proarrhythmic substrate, we hypothesized that BVR in SCD dogs are larger than in matched control chronic AVB dogs. From a population of 200 chronic AVB dogs, initially two groups were chosen retrospectively: 8 dogs that died suddenly (SCD) and 8 control dogs. Control dogs had a longer lifespan after AVB (10 to 18 weeks) than SCD dogs (5 to 10 weeks). All dogs had undergone electrophysiological testing under anesthesia where ECG, left and right ventricular endocardial monophasic action potentials (MAP) were recorded. BVR was assessed from 30 consecutive beats, illustrated by Poincare plots and was the only parameter discriminating between SCD and control group. All other electrophysiological parameters (RR, QT and MAP durations) were comparable for the two groups. Extending the number of animals and groups confirmed a larger BVR in the SCD group (SCD: 5.1 +/- 2.7; n = 11 versus control: 2.5 +/- 0.4 ms; n = 61; P < 0.05) and showed reverse-use dependence of BVR. In comparison, dogs with acute AVB had low variability (1.3 +/- 0.3 ms; n = 9; P < 0.05 versus chronic AVB). Cardiac electrical remodeling after AVB is associated with an increase in beat-to-beat variability of repolarization. Chronic AVB dogs displaying further elevated variability of repolarization are prone to arrhythmia-related SCD.

Action Potentials↗

PubMed2005

Domestic dogs (Canis familiaris) use a physical marker to locate hidden food.

Dogs can use the placement of an arbitrary marker to locate hidden food in an object-choice situation. We tested domestic dogs (Canis familiaris) in three studies aimed at pinning down the relative contributions of the human's hand and the marker itself. We baited one of two cups (outside of the dogs' view) and gave the dog a communicative cue to find the food. Study 1 systematically varied dogs' perceptual access to the marker placing event, so that dogs saw either the whole human, the hand only, the marker only, or nothing. Follow-up trials investigated the effect of removing the marker before the dog's choice. Dogs used the marker as a communicative cue even when it had been removed prior to the dog's choice and attached more importance to this cue than to the hand that placed it although the presence of the hand boosted performance when it appeared together with the marker. Study 2 directly contrasted the importance of the hand and the marker and revealed that the effect of the marker diminished if it had been associated with both cups. In contrast touching both cups with the hand had no effect on performance. Study 3 investigated whether the means of marker placement (intentional or accidental) had an effect on dogs' choices. Results showed that dogs did not differentiate intentional and accidental placing of the marker. These results suggest that dogs use the marker as a genuine communicative cue quite independently from the experimenter's actions.

Animals↗

PubMed1978

Plasma concentrations and tissue uptake of free amino acids in dogs in sepsis and starvation: effects of glucose infusion--some effects of low alimentation.

The plasma concentrations of substrates, together with transhepatic and transgut balances, have been studied in six control and eight septic awake fasted dogs. Four severely ill septic dogs (typically fluid in chest and/or abdomen, extensive peritonitis, respiratory difficulties) had high concentrations of threonine, glycine, tyrosine, lysine, histidine, tryptophan, and triglycerides (p less than or equal to 0.05). The other septic dogs (less severely ill) showed fewer and less pronounced alterations in the plasma substrates (aspartate and tryptophan were elevated, p less than or equal to 0.05). The infusion of glucose increased the concentration of glucose, lactate, and pyruvate and depressed the concentrations of most amino acids in both normal and septic dogs. Threonine, asparagine, glutamine, leucine, isoleucine, alpha-aminobutyrate, and tyrosine were significantly depressed in the severely ill septic dogs (p less than or equal to 0.05). In the normal dogs most amino acids were removed by the liver, with alanine accounting for approximately 40% of the total. Glutamine removal was negligible. In the septic dogs hepatic removal of amino acids was variable; livers of two severely ill septic dogs did not remove amino acids. In the control dogs glucose infusion (0.015--0.017 g/kg/min) tended to lower hepatic removal of amino acids. Hepatic dye removal in the septic dogs was always very poor. In the gut glutamine was removed and alanine, glutamate, glycine, and ammonia produced, but the overall sum of amino acid uptake was negligible in both the control and septic dogs. The ratio of tryptophan to the sum of valine, isoleucine, leucine, tyrosine, and phenylalanine concentrations was greatly elevated in all septic dogs in which it was measured. The free concentrations of amino acids in the liver, heart, and muscle tissues were grossly elevated in the low intravenous alimented septic state relative to the fasted normal state, whereas the tissue concentrative ability as measured by nonmetabolizable amino acids, alpha-aminoisobutyrate and cycloleucine, was not similarly increased. Sepsis clearly alters plasma and tissue concentrations, and in some instances hepatic uptake of amino acids.

Amino Acids↗

PubMed1992

Effect of FK506 on insulin secretion in normal dogs.

In this report, we describe the effect of FK506 on glucose-mediated insulin release in normal dogs. Dogs were placed into one of two groups, group 1 dogs received FK506 (1 mg/kg/d orally) for 2 weeks, and group 2 dogs received FK506 at the same dose, but for 4 weeks. Following the treatment period, both groups of dogs were allowed a recovery period during which time no FK506 was administered. Intravenous glucose tolerance tests (IVGTT) were performed (0.5 mg/kg IV) before FK506 treatment, after 2 or 4 weeks of treatment, and following the recovery periods. Complete blood cell counts (CBC) and serum chemistries were also obtained at these times. Following FK506 treatment for either 2 or 4 weeks, the dogs experienced a delay in glucose disappearance in response to IV glucose injection. Insulin secretion during IVGTT was unchanged in dogs treated for only 2 weeks, but was significantly decreased in dogs treated for 4 weeks. Following the recovery period, glucose disappearance during IVGTT returned to normal in dogs that were treated for 2 weeks, and was more rapid than normal in dogs that had been treated for 4 weeks. Insulin secretion after the recovery period remained unchanged in group 1 dogs, but continued to be significantly reduced in group 2 dogs that had received FK506 for 4 weeks. No significant change was detected in the CBCs or serum chemistries.

Animals↗

PubMed1976

Respiratory characteristics of blood from Basenji dogs with classical erythrocyte pyruvate kinase deficiency.

The oxygen affinities of blood from eight Basenji dogs homozygous for classical erythrocyte pyruvate kinase deficiency and four dogs heterozygous for the defect were compared with blood from 14 Labrador retrievers and two normal Basenji dogs. The homozygous dogs showed significant anemia compared to heterozygous and normal dogs (P is less than 0.01). The average blood P50 value (at 38C and plasma pH of 7.40) for both homozygous and heterozygous dogs was significantly higher (P is less than 0.01) than for normal dogs (33.6+/-0.4 and 31.8+/-0.7 vs 30.8+/-0.6 mm Hg). The concentrations of 2,3-DPG in the blood of both heterozygous and homozygous dogs were significantly higher than normal values. Four months after splenectomy P50 values declined to normal in four homozygous Basenji dogs without any change in the degree of anemia or blood 2,3-DPG concentrations. Iron kinetic studies showed a shorter plasma clearance time in a homozygous than in a normal dog with the heterozygote falling midway between. The red cell life span in the normal and heterozygous dogs was approximately 120 days. The 59Fe studies on the homozygous dog indicate markedly different survival characteristics which can be attributed to the existence of three populations of red cells differing in their life spans.

Animals↗

PubMed1988

Single dose or fractionated total body irradiation and autologous marrow transplantation in dogs: effects of exposure rate, fraction size, and fractionation interval on acute and delayed toxicity.

Dogs were given single dose or fractionated total body irradiation (TBI) and autologous marrow grafts to prevent death from myelosuppression. Acute and delayed non-marrow toxicities were compared. Fifty-six dogs were given single dose TBI at 2.1 (n = 13), 5 (n = 12), 10 (n = 15), or 20 (n = 16) cGy/min. Acute radiation toxicity and mortality was related to the exposure rate; radiation doses resulting in 50% mortality at 7 days (LD 50/7) at 2.1, 5, 10 and 20 cGy/min were 1,692, 1,499, 1,261, and 1,056 cGy respectively. Fifty-three dogs were given fractionated TBI, 200 cGy three times a day with 6-hour intervals at 2.1 (n = 13), 5 (n = 9), 10 (n = 13), or 20 (n = 18) cGy/min. The LD 50/7 at the four exposure rates were 1,628, 1,470, 1,184, and 1,320 respectively. Thus, for exposure rates of 2.1, 5, and 10 cGy/min, the tolerated doses were comparable for single dose and fractionated TBI. At 20 cGy/min dose fractionation appeared to offer some advantage, although this fractionation effect in part may have been due to random variation with small numbers of dog treated. Following recovery from the immediate TBI-related toxicity, eight dogs given single dose and four dogs given fractionated TBI died, generally from infections, 8-30 days following transplantation. There was a striking difference in regards to long-term survival dependent upon the TBI regimen. Among dogs given greater than or equal to 1,000 cGy of TBI and alive 30 days after transplant only 1 of 18 given single dose TBI became a long-term survivor compared to 19 of 22 given fractionated TBI. Causes of death included pancreatic fibrosis, malnutrition, hepatic failure, and a generalized wasting syndrome. All 5 dogs given a single dose of 800 cGy (at 20 cGy/min) became long-term survivors. Fourteen dogs were given increments of 150 cGy at 7 cGy/min every 3 hours for total doses of 1,500-2,400 cGy. The LD 50/7 was approximately 1,900 cGy. All 6 dogs alive at 30 days became healthy long-term survivors. Four dogs were given increments of 600 cGy at 2.1 cGy/min every 48 hours for a total dose of 1,800 cGy. All 4 dogs became long-term survivors. In conclusion, exposure rate and total dose are the most important parameters for acute toxicity associated with TBI. The effect of dose fractionation is minimal at low exposure rates and appears to be dependent also upon increment size and fractionation interval.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed2006

Relationships among dog ownership and leisure-time walking in Western Canadian adults.

BACKGROUND: Dog ownership may be an effective tailored intervention among adults for promoting physical activity. This study examined the relationship between walking, physical activity levels, and potential psychological mediators between people who owned dogs and those who did not own dogs in the Capital Region District of Greater Victoria, British Columbia, Canada. Data were collected in September 2004; analyses were conducted in January 2005. METHODS: A random sample of men (n=177) and women (n=174) aged 20 to 80 years participated. Questionnaires were mailed out in 2004 to collect information about demographics, dog ownership, leisure-time walking, physical activity levels, and theory of planned behavior (TPB) constructs. RESULTS: The analyses revealed that dog owners spent more time in mild and moderate physical activities and walked an average of 300 minutes per week compared to non-dog owners who walked an average of 168 minutes per week. A mediator analysis suggests that dog obligation acts as a mediator between dog ownership and physical activity. Moreover, the theory of planned behavior constructs of intention and perceived behavioral control explained 13% of the variance in walking behavior with an additional 11% variance in walking behavior being explained by dog obligation. Regarding intention to walk, the TPB explained 46% of the variance in intention to walk with dog obligation adding an additional 1% variance. CONCLUSIONS: In this group of Canadians, those who owned a dog participated in more mild to moderate physical activity than those who did not. Acquiring a dog should be explored as an intervention to get people more physically active.

Adult↗

PubMed2006

Photodynamic therapy with motexafin lutetium for rectal cancer: a preclinical model in the dog.

PURPOSE: Local recurrence of rectal cancer remains a significant clinical problem despite multi-modality therapy. Photodynamic Therapy (PDT) is a cancer treatment which generates tumor kill through the production of singlet oxygen in cells containing a photosensitizing drug when exposed to laser light of a specific wavelength. PDT is a promising modality for prevention of local recurrence of rectal cancer for several reasons: tumor cells may selectively retain photosensitizer at higher levels than normal tissues, the pelvis after mesorectal excision is a fixed space amenable to intra-operative illumination, and PDT can generate toxicity in tissues up to 1 cm thick. This study evaluated the safety, tissue penetration of 730 nm light, normal tissue toxicity and surgical outcome in a dog model of rectal resection after motexafin lutetium-mediated photodynamic therapy. METHODS: Ten mixed breed dogs were used. Eight dogs underwent proctectomy and low rectal end to end stapled anastomosis. Six dogs received the photosensitizing agent motexafin lutetium (MLu, Pharmacyclics, Inc., Sunnyvale, CA) of 2 mg/kg preoperatively and underwent subsequent pelvic illumination of the transected distal rectum of 730 nm light with light doses ranging from 0.5 J/cm(2) to 10 J/cm(2) three hours after drug delivery. Two dogs received light, but no drug, and underwent proctectomy and low-rectal stapled anastomosis. Two dogs underwent midline laparotomy and pelvic illumination. Light penetration in tissues was determined for small bowel, rectum, pelvic sidewall, and skin. Clinical outcomes were recorded. Animals were sacrificed at 14 days and histological evaluation was performed. RESULTS: All dogs recovered uneventfully. No dog suffered an anastomotic leak. Severe tissue toxicity was not seen. Histological findings at necropsy revealed mild enteritis in all dogs. The excitation light penetration depths were 0.46 +/- 0.18, 0.46 +/- 0.15, and 0.69 +/- 0.39 cm, respectively, for rectum, small bowel, and peritoneum in dogs that had received MLu. For control dogs without photosensitizer MLu, the optical penetration depths were longer: 0.92 +/- 0.63, 0.67 +/- 0.10, and 1.1 +/- 0.80 cm for rectum, small bowel, and peritoneum, respectively. CONCLUSION: Low rectal stapled anastomosis is safe when performed with MLu-mediated pelvic PDT in a dog model. Significant tissue penetration of 730 nm light into the rectum and pelvic sidewall was revealed without generation of significant toxicity or histological sequelae. Penetration depths of 730 nm light in pelvic tissue suggest that microscopic residual disease of less than 5 mm are likely to be treated adequately with MLu-mediated PDT. This approach merits further investigation as an adjuvant to total mesorectal excision and chemoradiation for rectal cancer.

Anastomosis, Surgical↗

PubMed2006

Effects of a GnRH cytotoxin on reproductive function in peripubertal male dogs.

Methods for long-term or permanent disruption of reproductive function via nonsurgical techniques are needed for a variety of species, including companion animals. In a previous study, we demonstrated the ability of a cytotoxin (pokeweed antiviral protein-PAP) conjugated to d-Lys(6)-GnRH, to disrupt reproductive function in adult male dogs. The objective of the present study was to examine the ability of a d-Lys(6)-GnRH-PAP conjugate to disrupt reproductive function in peripubertal male dogs. Peripubertal male dogs (n=15; approximately 16-32 weeks old) were treated with d-Lys(6)-GnRH-PAP as follows: dogs (n=7; Group I) received GnRH-PAP (0.1 mg/kg SQ) with a second treatment (0.25 mg/kg) 20 weeks later. An additional group (n=3; Group II) of peripubertal dogs was treated with GnRH-PAP (0.25 mg/kg) twice (20 weeks apart). Control dogs (n=5) received d-Lys(6)-GnRH analog (0.0045 mg/kg SQ) without PAP. Efficacy was assessed by monitoring testis size, serum concentrations of testosterone and LH, as well as LH release subsequent to a GnRH (5 microg/kg) stimulus. Dogs in Group I (n=5) that did not respond to the initial two treatments were given a third GnRH-PAP injection (0.25 mg/kg), 12 months after the initial treatment. The initial GnRH-PAP treatment in peripubertal male dogs did not affect testis growth, LH release or serum testosterone concentrations; however, administration of a higher dose of GnRH-PAP after puberty resulted in a marked and rapid decline in testis size, serum testosterone concentrations and LH responsiveness to GnRH stimulation in 9 of 10 dogs. Suppression of reproductive function was maintained in treated dogs for 18-50 weeks; four dogs had suppression of reproductive activity through the end of the study. In conclusion, GnRH-PAP given after puberty markedly suppressed reproductive activity. Due to variability in the response and duration of suppression after treatment with GnRH-PAP, more research is required to determine its efficacy for nonsurgical sterilization of the male dog.

Animals↗

PubMed1999

Nitric oxide modulation of the growth hormone-releasing activity of Hexarelin in young and old dogs.

The growth hormone (GH)-releasing activity of Hexarelin, a potent GH-releasing peptide (GHRP) analog, was evaluated in eight young (aged 1 to 6 years) and five old (10 to 16 years) beagle dogs pretreated with erythrityl tetranitrate, a liposoluble nitric oxide (NO) donor, and/or indomethacin, an inhibitor of cyclooxygenase enzymes, and N-nitro-L- or N-nitro-D-arginine methylester (L-NAME and D-NAME), active and inactive NO synthase (NOS) inhibitors, respectively. Erythrityl tetranitrate (0.3 mg x kg(-1) oral [p.o.]) strikingly potentiated Hexarelin-stimulated GH secretion (31.25 microg x kg(-1) intravenous [i.v.]) in both young (area under the time-concentration curve at 0 to 90 minutes AUC(0-90)] 878.50 +/- 267.02 v 1,994.04 +/- 434.20 ng x mL(-1) x h, P < .01) and aged animals (314.82 +/- 117.11 v 1,314.12 +/- 484.75 ng x mL(-1) x h, P < .01). The NO donor alone did not modify baseline GH levels in either young dogs (188.68 +/- 85.24 ng x mL(-1) x h) or old dogs (120.49 +/- 22.03 ng x mL(-1) x h). L-NAME (5 mg x kg(-1) x 2 i.v.) suppressed GH release induced by the peptide in young dogs (1,367.68 +/- 251.87 v 411.12 +/- 68.49 ng x mL(-1) x h, P < .01), but potentiated it in old dogs (314.73 +/- 117.10 v 1,103.97 +/- 374.11 ng x mL(-1) x h, P < .01). D-NAME (5 mg x kg(-1) x 2 i.v.) did not affect the GH response to Hexarelin in either young (1,328.68 +/- 433.54 ng x mL(-1) x h) or aged (342.32 +/- 84.82 ng x mL(-1) x h) dogs. Indomethacin (1.5 mg x kg(-1) i.m.) abolished the NO-donor potentiation of the GH response induced by Hexarelin in both young dogs (1,627.25 +/- 260.90 v 1,163.37 +/- 334.84 ng x mL(-1) x h, P < .05) and old dogs (1,061.47 +/- 210.38 v 365.69 +/- 79.27 ng x mL(-1) x h, P < .01) without affecting the plasma GH peak evoked by the peptide alone (young dogs, 786.04 +/- 153.44 v 960.04 +/- 444.44 ng x mL(-1) x h, P = NS; old dogs, 474.55 +/- 47.30 v 490.82 +/- 144.86 ng x mL(-1) x h, P = NS). In conclusion, (1) NO donors are capable to further increase the strong GH-releasing activity of Hexarelin in both young and old dogs, although the site(s) and mechanism(s) of action of NO is still obscure; (2) the different GH response to the peptide after NOS inhibition in young and old dogs signifies in the latter an alteration of the somatotrope function; and (3) prostaglandins are the downstream effectors of the chain of events triggered by activation of the NO-ergic system.

Aging↗

PubMed1999

Chronic stress in dogs subjected to social and spatial restriction. I. Behavioral responses.

Six weeks of social and spatial restriction were used as a model to induce chronic stress in Beagles. Behavioral and physiological measurements were performed during a period of enriched spacious outdoor housing in groups (GH) and during a subsequent period of solitary housing in small indoor kennels (IH). Behavioral parameters that may indicate chronic stress in dogs are reported. During IH, the dogs showed significantly (comparison-wise error rate <0.05) lower postures than during GH. IH induced enduring increments in frequencies of autogrooming, paw lifting, and vocalizing, and was associated with incidents of coprophagy and repetitive behavior. So far, we interpret the behavioral changes as signs of chronic stress. Relatively low levels of walking, digging, intentions to change from one state of locomotion to another, and increments in circling are conceived as obvious adaptations to the specific features of the IH system. By challenging the dogs outside their home kennel we tested whether the dogs' coping abilities were affected by IH. Dogs that were challenged were introduced into a novel environment, given the opportunity to escape from their home kennel, restrained, walked down an unfamiliar corridor, presented a novel object, exposed to loud noise, given food, or confronted with a conspecific. During IH, challenged dogs exhibited higher postures, showed more tail wagging, nosing, circling, urinating, and defecating, and changed more often from one state of locomotion (or posture) to another than during GH. These behavioral changes were observed across the different types of challenges, with the exception of the noise administration test. In the presence of conspecifics, the socially and spatially restricted male dogs behaved more dominantly and aggressive than during the time that they were kept in groups. Such behavior manifested as increased performances of raised hairs, growling, paw laying, and standing over. Both sexes showed increases in paw lifting, body shaking, ambivalent postures, intentions to change from one state of locomotion to another, and trembling in any of the challenges, excluding the walking down the corridor test. In short, during a variety of challenges, socially and spatially restricted dogs exhibited a heightened state of aggression, excitement, and uncertainty. Behavioral differences between dogs that had experienced pleasant and bad weather conditions during GH, suggested that "pleasant-weather individuals" had experienced early stress during the control period, and, as a result, responded to the subsequent period of IH differently. Regardless of the housing conditions, challenged bitches showed stronger indications of acute stress than male dogs. Gender did not affect the chronic stress responses to social and spatial restriction. A low posture and increased auto-grooming, paw lifting, vocalizing, repetitive behavior, and coprophagy may indicate chronic stress in dogs, and as such, can help to identify poor welfare. When challenged, chronically stressed dogs may show increased excitement, aggression, and uncertainty, but the nonspecificity of such emotional behavior will complicate its practical use with regard to the assessment of stress.

Animals↗

PubMed1997

Major cat and dog allergens share IgE epitopes.

BACKGROUND: Patients allergic to cats and dogs frequently display IgE reactivity against allergens from different animals, suggesting a cross-sensitization to common allergenic determinants. Although albumins have been recognized as relevant cross-reactive allergens, little is known regarding cross-reactive epitopes of the major cat and dog allergens. OBJECTIVE: In this study, sera from patients allergic to cats and/or dogs were used to investigate the presence of common IgE epitopes among the major cat and dog allergens. METHODS: The IgE reactivity profile of 109 patients who were allergic to allergens from several species of animals was determined with nitrocellulose-blotted cat and dog allergens. Sera from patients who were strongly allergic to the major cat and dog allergens were tested for the presence of cross-reactive IgE antibodies by one-dimensional and two-dimensional immunoblot inhibition experiments and by quantitative measurements obtained with the CAP-FEIA system (Pharmacia). RESULTS: Sixty-eight of 109 patients with animal allergy showed IgE reactivity to cat allergens and dog allergens. Sera from patients with both cat and dog allergy detected allergens of similar molecular weight in nitrocellulose-blotted cat and dog hair/dander extracts. Common, as well as species-restricted, IgE epitopes of the major cat and dog allergens could be demonstrated by IgE inhibition studies. CONCLUSION: Shared IgE epitopes of the major cat and dog allergens may provide an explanation for the clinical observation that allergies to cats and dogs are frequently associated.

Albumins↗

PubMed2002

Effect of insecticide-impregnated dog collars on incidence of zoonotic visceral leishmaniasis in Iranian children: a matched-cluster randomised trial.

BACKGROUND: Deltamethrin-impregnated dog collars reduce sandfly bite rates on dogs, and are effective in killing sandflies that attempt to feed. Because domestic dogs are the principal reservoir hosts of zoonotic visceral leishmaniasis, we tested whether community-wide application of dog collars could protect children against infection with Leishmania infantum, the parasite that causes the disease. METHODS: 18 villages were paired, matched by preintervention child prevalence of L infantum infection. Within pairs, villages were randomly assigned to either control or intervention. All domestic dogs in intervention villages were provided with collars for the transmission season. The main outcome measure was incidence of L infantum infection after 1 year measured by seroconversion. Secondary outcomes were leishmanin skin test (LST) conversion and seroconversion in dogs. FINDINGS: The seroconversion rate in children was 1.49% (17/1141) in the intervention villages and 2.41% (26/1078) in control villages (odds ratio 0.57, 95% CI 0.36-0.90, p=0.017). LST conversion was also lowered, but not significantly (odds ratio 0.66, 0.41-1.08, p=0.096). The seroconversion rate in dogs in intervention villages was also significantly reduced (0.46, 0.30-0.70, p=0.0003). INTERPRETATION: Community-wide application of deltamethrin-impregnated dog collars not only protects domestic dogs from L infantum infections, but might also reduce the risk of L infantum infection in children. These dog collars could have a role in control of visceral leishmaniasis and replace controversial dog culling programmes in some countries. However, the effectiveness of dog collars will depend on the importance of wild versus domestic canids as reservoir hosts of L infantum.

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