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Biomedical subjects

B W Knol

Publications and source records attributed to B W Knol.

At least 19 recordsLinked to original sources
PubMed1994

Behavioural, household, and social problems associated with companion animals: opinions of owners and non-owners.

The goal of this investigation was to determine the extent to which owners of companion animals experienced problems with their animals, such as behaviour problems, and to discover their opinion about household problems such as the shedding of hairs and/or feathers. Furthermore, an attempt was made to discover the opinions of owners and non-owners about social problems such as 'companion animals make noise'. The findings are the result of a survey among 871 Dutch respondents. It was found that 43% of all companion animal owners had one or more problems with their animals. Dog and cat owners experienced many problems with the illness and the behaviour of their animals. The higher the income of the owner, the more likely he/she is to have problems with his/her animal's behaviour. Because animals with behaviour problems are a risk group, more should be done to prevent these problems. Owners of companion animals found shedding of hair or feathers the biggest disadvantage of keeping an animal. People in paid employment found cleaning the cage of the animal a bigger nuisance than did people not in paid employment. There were no differences in owner characteristics with regard to the household problems. The opinions of owners of certain species of animals, owners of other species, and non-owners about behavioural traits and the nuisance caused by that species of companion animal differed, which could lead to misunderstandings between these groups.

Animal Husbandry↗
PubMed1993

Hereditary necrotising myelopathy in Kooiker dogs.

A retrospective clinicopathological study of a neurological disorder in 22 Kooiker dogs (Dutch decoy dog) was made. The disease was found to occur equally in both sexes and clinical signs began at three to 12 months old. Physical examination revealed a progressive paresis of the hindlimbs. Post mortem examination showed symmetrical areas of malacia in the ventral, lateral and dorsal white matter of the spinal cord. In one dog dorsal white matter was spared. Cervical segments C4 to C8 were involved in all subjects. Rostral and caudal to these areas, Wallerian degeneration was prominent. The disease has much in common with similar myelopathies in the Afghan hound and the rottweiler. Indications of heritability were the similarity in clinical and pathological findings, the age of onset of the disease, and the significantly higher inbreeding coefficient in the patients than in the breed population (P = 0.001). All patients were descended from one pair. Segregation analysis suggested inheritance involving a simple autosomal recessive trait.

Animals↗
PubMed1993

GnRH in the male dog: dose-response relationships with LH and testosterone.

Dose-response relationships between GnRH and LH, and between GnRH and testosterone, were investigated in six male dogs by intravenous administration of a GnRH analogue at different doses. Each dose of GnRH analogue induced an immediate rise in the plasma concentration of LH and then a rise in plasma testosterone concentration. Irrespective of the dose used, the rise in testosterone began 10 min after the GnRH injection. Administration of GnRH at doses of 0.01, 0.1, 1, 10 and 100 micrograms kg-1 resulted in maximum LH concentrations in plasma (mean +/- SEM; n = 6) of 22 +/- 7, 27 +/- 6, 40 +/- 7, 57 +/- 13 and 56 +/- 10 micrograms l-1, respectively. These doses induced maximum concentrations of testosterone in plasma (mean +/- SEM; n = 6) of 16 +/- 4, 20 +/- 4, 22 +/- 3, 22 +/- 4 and 24 +/- 7 nmol l-1, respectively. The lag time between peak concentrations of LH and testosterone varied from 35 to 55 min. The calculated maximum response of testosterone to LH, secreted by the anterior pituitary after GnRH injection, was 1.8 times higher than to GnRH. It was concluded that intravenous administration of GnRH induced marked and dose-dependent increases in plasma concentrations of LH and testosterone, and that there does not appear to be a direct effect of GnRH on Leydig cells in male dogs.

Animals↗
PubMed1992

[Owner and dog: like seeks like?].

The aim of this investigation was to find out whether there are similarities or differences between the personality of the dog owner and the character of his of her dog. Ten owners of four different breeds of dog (40 owners in total) participated in this investigation. Some of the findings indicate resemblances in the character of the owners of certain breeds of dog. However to test the significance of these results more respondents are needed and a uniform character test for the dogs must be used.

Animals↗
PubMed1992

Effects of methods used for blood collection on plasma concentrations of luteinising hormone, testosterone, and cortisol in male dogs.

The effects of two putative stressors relative to the collection of blood, namely the environment of the treatment room and the pain associated with venepuncture, on plasma levels of luteinising hormone (LH), testosterone and cortisol were examined in six trained male experimental dogs. Blood samples were collected from the dogs in a treatment room as well as in the kennels (control), and by venepuncture as well as via an indwelling intravenous catheter (control). No significant influence of either stressor on plasma levels of LH, testosterone or cortisol was found. Plasma concentrations of these hormones varied considerably both between and within dogs. Mean (+/- SEM; n = 6) plasma concentrations were 4.3 +/- 1.0 micrograms/l for LH, 4.6 +/- 1.9 nmol/l for testosterone and 68 +/- 10 nmol/l for cortisol. It was concluded that the putative stressors, the environment of the treatment room and the pain associated with venepuncture, did not significantly influence plasma levels of LH, testosterone or cortisol in trained male experimental dogs. This conclusion implies that under the experimental conditions described, the validity of results will not be affected by the method of blood collection used.

Animals↗
PubMed1992

The relationship between homozygosity and the occurrence of specific diseases in Bouvier Belge des Flandres dogs in The Netherlands.

Since purebred dog populations represent closed gene pools, a relatively high level of consanguinity between individuals, and hence of inbreeding, is common. This case control study was conducted to establish the possible connection between the actual level of homozygosity due to inbreeding and specific diseases (flea allergy, osteochondrosis, laryngeal paralysis, neoplasm, autoimmune disease, hypoplastic trachea, and food allergy) occurring in the Bouvier Belge des Flandres breed. One hundred and sixty-eight animals referred to the Utrecht University Clinic formed the patient group. Each of the seven diseases was chosen because of the demonstrability of the diagnosis. Each animal was chosen because one of the selected diseases was established in that individual, and because its pedigree was complete. All dogs of the patient group were born between 1 January 1980 and 31 December 1985. A control group (n = 123) was randomly chosen from the total population of registered Bouviers born in the Netherlands in the same period. pedigree data were obtained from the Dutch Kennel Club. The extent of inbreeding was determined for all animals using Wright's inbreeding coefficient. The distribution of inbreeding coefficients in each patient group was compared with the distribution in controls. Inbreeding coefficients in the control group ranged from 0.0 to 0.406. Animals in which osteochondrosis, food allergy, autoimmune disease, neoplasm, or hypoplastic trachea was diagnosed had higher inbreeding coefficients than controls. It was concluded that in the Bouvier Belge des Flandres dog population examined, the level of homozygosity was positively correlated with occurrence of these diseases.

Animals↗
PubMed1992

Pituitary-dependent hyperadrenocorticism in a family of Dandie Dinmont terriers.

Adrenocortical function studies were performed in seven Dandie Dinmont terriers with pituitary-dependent hyperadrenocorticism. The ability of dexamethasone at a dose rate of 0.1 mg/kg body weight to suppress cortisol secretion was only moderate in four out of the six dogs tested. Concentrations of alpha-melanocyte-stimulating hormone in plasma were highly increased. Responses to stimulation with corticotrophin-releasing hormone and the dopamine-antagonist haloperidol, examined in three animals, were moderate or absent. These results indicate that adrenocortical stimulation, i.e. hyperadrenocorticotrophism, was caused by pituitary lesions which were functioning autonomously. In six of the seven animals there was a very close familial relationship and the coefficients of relationship and the coefficients of inbreeding were significantly higher than in a representative control population. It was concluded that these seven related terriers with hyperadrenocorticotrophism had the biochemical characteristics of de-novo neoplasms of proopiomelanocortin-producing cells, and there was evidence for a genetic involvement in tumorigenesis.

Adenocarcinoma↗
PubMed1991

Stress and the endocrine hypothalamus-pituitary-testis system: a review.

Stressors generally induce a depression of the hypothalamus-pituitary-testis (HPT) system, mediated by the activated hypothalamus-pituitary-adrenocortical (HPA) system, resulting in a fall in plasma luteinising hormone (LH) and testosterone levels. Hypothalamic gonadotrophin-releasing hormone (GnRH) secretion may be suppressed by endogenous opioid peptides (EOP) and/or corticosteroids. The latter dramatically enhance the negative feedback effects of testosterone on both the hypothalamus and pituitary. Pituitary gonadotrophin secretion may be reduced by adrenocorticotrophic hormone or by EOP of hypothalamic or pituitary origin. Decreases in plasma concentrations of testosterone, independent of gonadotrophins, can be induced by corticosteroids. These hormones might reduce the number of Leydig-cell LH-receptors or occupation of LH-receptors. Testicular steroidogenesis may also be inhibited by pro-opiomelanocortin-derived (opioid) peptides secreted by the Leydig cells. There are some indications of increases in LH and testosterone during acute stress and, in dominant male animals, during the stress of social conflict. The latter finding indicates a difference in stress response between dominant and subordinate males. In subordinate males, decreased feedback sensitivity may allow hypersecretion throughout the HPA system. As a result, corticotrophin releasing hormone may induce the release of EOP from the hypothalamus, which inhibit the HPT axis. This inhibition may be enhanced by a corticosteroid-induced decrease in testosterone feedback.

Animals↗
PubMed1989

Androgens, progestagens and agonistic behaviour: a review.

The relationship between androgens, progestagens and agonistic behaviour is reviewed. Most literature concerned the effects of hormones on aggression; little information was available on hormonal influences on fear. Difference in aggression levels between males and females may be explained by assuming the existence of a gender difference in motivation, which, among other factors, is controlled by androgen and progestagen levels in peripheral blood. Androgens and progestagens are metabolised mainly by 5 alpha-reductase in the target organs. In the brain, aromatisation of testosterone also plays a role. The metabolites of testosterone may exert the same organising and activating influence as testosterone on juvenile and adult brain tissue, respectively. In some animal species testosterone secretion appears to be influenced by social and environmental variables. Conversely, alterations in plasma androgen levels have been found to affect behaviour. Dominant and/or aggressive individuals tend to show higher plasma testosterone levels than submissive and/or less aggressive animals. Among other mechanisms, competitive inhibition of androgen action at a central level, by progestagens acting as antagonists of androgens, may be important.

Aggression↗
PubMed1989

Treatment of problem behaviour in dogs and cats by castration and progestagen administration: a review.

Treatment of problem behaviour in companion animals by castration and progestagen administration is reviewed. In male dogs castration is effective in eliminating roaming and, to a lesser extent, mounting, urine marking and intermale aggression. Spraying, roaming and fighting behaviour in cats disappear almost completely after castration. In the latter species prepubertal castration does not seem to be more effective in preventing this problem behaviour than postpubertal castration is in eliminating it. In dogs, intermale aggression, urine marking, mounting and roaming have been treated successfully with progestagens; in cats the same treatment has been successful in decreasing fighting and roaming. There are no reports on the ethical aspects or on adverse side effects of castration. For progestagens a wide range of undesirable side effects have been described. The results of both castration and progestagen therapy differ in the various studies. The underlying mechanism(s) of progestagen influence on behaviour are not understood. Therefore, future research on this topic is necessary.

Animals↗
PubMed1988

The suitability of dogs as guide dogs for the blind: criteria and testing procedures.

Criteria and testing procedures with regard to the suitability of dogs as guide dogs for the blind were developed on the basis of a literature study and own observations. A profile of the guide dog comprising physical characteristics, skillfulness, behaviour, and obedience was drawn up. As a rule, the testing procedures concern health and skills of the dogs. In the skill test some elements of the behavioural and obedience test were included. The final evaluation is based on the results of physical examination and the skill test, unless testing of behaviour and/or obedience appears necessary as well. A method for evaluating the performance of the dogs as objectively as possible is described. Some implications of using and testing guide dogs are discussed.

Animals↗