Dangerous dogs: application of federal regulations

During the last years nearly in all provinces in Germany new, hotly debated rules were published in order to meet the threat dangerous dogs or so-called fighting dogs mean to animals and men. Comparing current regulations of different provinces two categories of rules can be identified: one considering particular breeds as extremely dangerous and the other defining and characterising the dangerous dog. The application of these regulations differs enormously in expenditure and procedure. Recent statistics of all registered dog-bites allow other conclusions than those which seemed to have been relevant for the elaboration of the existing legislation. This is particularly true for the breeds which are considered extremely dangerous. It seems to be more useful to use the expression dangerous dog in general. Routine application of the new regulations have, except from some cases, increased administrative input but have not improved the situation itself. Animals homes are complaining of more "fighting" dogs. The fact that it is extremely difficult to find a new owner for these dogs leads to additional animal health problems. Judgement and treatment of dogs presented to public authorities because of dog-biting has not become any easier and dogs causing severe injury are not even presented. The new regulations are not sufficiently preventive and do not really tackle the cause of the problem of dangerous dogs. The existing regulations were developed under a strong political pressure. Authorities are now calling into question the usefulness and purpose of the new legislation. In the past the problem of dangerous dogs was dealt with using general safety legislation and police regulations offering flexibility. Obviously there is an urgent need to identify countermeasures on a larger scale.     

Recognizing and assessing aggressive behaviour in dogs

Within the population the sensitivity to aggressive behaviour in dogs has increased. The authorities are confronted with a problem: if any incident occurs it is their task to decide whether the dogs involved constitute a threat to other people or whether the charge is only the result of a quarrel between neighbours. For this reason, an examination of the dogs with regard to their aggressive behaviour is necessary. Seen from the biological point of view, aggressive behaviour is one of four possibilities a dog can chose from to solve a conflict. The dog's intention in showing aggressive behaviour is to eliminate disturbances and to maintain a distance in space and time. Aggressive behaviour might also be necessary to acquire or defend resources essential to the dog's life. This is to secure its survival and its success in reproduction. One can see from this that aggressive behaviour is a very important and biologically necessary adjustment factor. However, when living together with man aggressive behaviour might become a problem. For the assessment and the therapy of the problem it is necessary to exa-mine the behaviour shown by the dog with regard to its cause. To be able to do this an exact anamnesis, a medical check, and an examination of the dog on the basis of its display in special situations are necessary. For this reason, exclusively veterinarians with a special further education in the field of behaviour should carry out the examination of dogs.     

Plasma amino acid concentrations in aggressive dogs

Following the hypothesis that metabolic screens may be useful tools in the diagnosis of canine aggression we have investigated the blood plasma amino acid levels of dogs which have been found aggressive (N = 10) against dogs or men in comparison to non-aggressive dogs (N = 10). In summary, the aggressive dogs showed elevated plasma concentrations of the neurophysiological active aromatic amino acids tryptophan (46/171 micromol/l, p < 0,001), tyrosine (38/67 micromol/l, p < 0.01) and histidine (74/91 micromol/l, p < 0.01) and lower lysine concentrations (175/151 micromol/l, p < 0.05), which seems to point to a stress situation of these dogs. The nitrogen metabolism is impaired in the urea-cycle in the conversion of ornithine (17/34 micromol/l, p < 0.01) to citrulline (64/47 micromol/l). Higher levels of branched chain amino acids, especially leucine (122/150 micromol/l, p < 0.01), mainly metabolized in muscles, and isoleucin (60/71 micromol/l, p < 0.05) show a high energy potential.The acidose-stimulator methionine (48/78 micromol/l, p < 0.01) proved elevated. The results show that the changed behavior in the aggressive dogs is also reflected in their free amino acid plasma concentrations, independent of the question whether these data are the cause or the result of the aggressivity.     

Evaluating aggressive behavior in dogs: a comparison of 3 tests

This study assessed the consistency with which aggressive behavior occurred across 3 different provocation tests that are currently used in practice to evaluate the behavior and safety of dogs. The aim of this study was not to validate the tests, but to evaluate tests that are not validated but are nevertheless being used in a legal context in Switzerland, by investigating the hypothesis that 3 different approaches, all claiming to correctly evaluate the behavior of dogs, should be expected to show significant agreement. The same 60 dogs were tested in 3 behavioral tests being used in Switzerland at the time of this study in the year 2003 (Test A: Test of the American Staffordshire Terrier Club; Test B: Halterprüfung; Test C: Test of the Canton of Basel-Stadt). “Intraspecific behavior” and “interspecific behavior toward humans” that might relate to potential aggressive behavior were of particular interest.The observed agreement among the 3 tests was compared relative to chance using a κ test. Significant but low levels of agreement were found among the 3 tests for the criterion “intraspecific behavior” (κ = 0.133, P = .014), with the highest correlation between Tests A and B (κ = 0.345, P < .001) and for the criterion “interspecific behavior” (κ = 0.135, P = 0. 014), with Tests A and B (κ = 0.220, P = .005) showing the highest correlation. However, significant absolute values of κ were low in all cases. In a further analysis, dogs evaluated to show no signs of potential aggression in the test situations by all 3 tests were eliminated, and the results of the remaining dogs (“interspecific behavior,” n = 23; “intraspecific behavior,” n = 29) were assessed for disagreement in pairwise combinations using a McNemar chi-square test. No significant levels of disagreement were found for “intraspecific behavior,” however, for “interspecific behavior,” Tests A and B (P = .035), and Tests B and C (P < .001) differed significantly, with no significant difference between Tests A and B (P = 0.11). The inconsistency of the results from different tests suggests test bias at the very least and questions the validity of these tests. Further work examining the validity of each individual test is warranted if they are to be used in a legal context.     

Comparison of thyroid analytes in dogs aggressive to familiar people and in non-aggressive dogs

A cross-sectional study was performed in order to examine the association between canine aggression to familiar people and serum concentrations of total thyroxine (TT4), free thyroxine (fT4), thyroxine autoantibodies (T4AA), total triiodothyronine (TT3), free triiodothyronine (fT3), triiodothyronine autoantibodies (T3AA), thyroid stimulating hormone (TSH), and thyroglobulin autoantibodies (TgAA). The subjects were 31 dogs historically aggressive to familiar people and 31 dogs with no history of aggression. Behavioral evaluation and physical examination were completed for each dog in addition to a complete blood count, serum chemistry panel, TT4, fT4 by equilibrium dialysis, TT3, fT3, TgAA, T3AA, and T4AA. Significant differences were found between the two groups with respect to only T4AA, which was increased in the aggressive group, but the concentrations for both groups were within the normal reference range. There were no differences between the two groups in the thyroid analytes most commonly measured by veterinary practitioners evaluating thyroid function in dogs. The results of this study revealed no significant difference between aggressive and non-aggressive dogs in the thyroid concentrations most commonly used to diagnose canine hypothyroidism.     

Differences in serotonin serum concentration between aggressive English cocker spaniels and aggressive dogs of other breeds

Aggression is one of the most common behavioral problems in dogs and may have important negative effects on public health, human–animal bond, and animal welfare. There is ample evidence showing a negative correlation between serum serotonin concentration and aggressive behavior in a variety of species, including the domestic dogs. This negative correlation is particularly pronounced in dogs that show impulsive aggression. Data obtained in some previous studies suggest that the English cocker spaniel (ECS) is more likely to show impulsive aggression than other breeds. Therefore, the aim of this study was to analyze possible differences in serum serotonin levels between aggressive ECS and aggressive dogs of other breeds. Nineteen ECSs presented for aggression at the Animal Behavior Service (School of Veterinary Science, Barcelona, Spain) were evaluated and compared with 20 aggressive dogs of other breeds attended at the same center. Serum serotonin levels were measured using an enzyme-linked immunosorbent assay method. Statistical analysis was done using the SPSS 15.0 for Windows. Aggressive ECSs had significantly (P < 0.001) lower levels of serum serotonin than aggressive dogs of other breeds (318.6 ± 67.1 and 852.77 ± 100.58 ng/mL, respectively). Variances were not significantly different between ECSs and other breeds (standard deviation = 449.84 ng/mL vs. 292.47 ng/mL, P > 0.05). This finding may explain why ECSs are more likely to show impulsive aggression than other breeds, and suggests that the ECS could be a good model to study the neurophysiologic mechanisms underlying impulsive aggression.     

Treatment of aggressive testicular tumors in four dogs.

In this report, the authors describe four dogs referred for diagnosis and treatment of unusual and aggressive testicular tumors. For the vast majority of dogs with testicular tumors, orchiectomy is curative. All dogs in this report had surgical resection, and three of four dogs were treated with cisplatin chemotherapy. Cisplatin is widely recognized as the most active agent in testicular cancer in human medicine.     

Dangerous dogs in Berlin in comparison to the dog population--ways to reduce the dangerousness of dogs

The law for handling and control of dogs in Berlin of September 29, 2004 was enacted to prevent the risks for humans and animals when ever they have contact with dogs. "Dangerous dogs" are defined by this law. There are 10 breeds of dogs supposed to be dangerous due to specific characteristics of their breed ("listed breeds"). The dangerousness of a dog's breed is not identical with the dangerousness of an individual dog. The subject of this study is to examine the potential dangerousness of dog breeds and not the individual dangerousness of a dog. This study refers to statistics of incidents between dogs and humans in Berlin for the years 1998 to 2004. The population density of a breed is based on the dogs assessed for tax purposes in Berlin of January 1, 2005 and on the dog registrations maintained at veterinary hospitals. The fourfold-table-test was used to compare the quantity of the recorded incidents of two statistically independent dog breeds. Of the total population of 107,804 tax assessed dogs in Berlin in 2004, 0.9% was documented as dogs involved in incidents with humans. The incidents per year decreased in the "listed breeds"about 68% and in the "unlisted breeds" about 41% during the last 7 years in Berlin. Therefore, the probability (the odds ratio) of a breed to be conspicuous was analysed.The values for the calculation of this probability were the number of dogs of a breed having been involved in incidents compared to the population of this breed based on tax records.The comparison of the probability of a breed with another to be conspicuous was used to compile a cluster of breeds which had the same probability to be conspicuous in 2004. A cluster was assessed for dogs of the following breeds: Sheep dogs, Rottweiler, Doberman, Pitbull Terrier and American Staffordshire Terrier. A listing of breeds is not the right way to reduce the potential dangerousness of a dog, especially in the private domain of their owners. Most incidents with dogs occur in the private domain which normally is not recorded in the statistics of incidents. Therefore, it is more effective to support activities which include the training of abilities of the dog owners.Training by experts can enable dog owners to avoid conflict situations with their dog, or in case of conflict, to take appropriate actions.     

Behavioral evaluation of 65 aggressive dogs following a reported bite event

Peer-reviewed scientific publications on the topic of dog bites are numerous. Montreal was one of the first municipalities in the province of Quebec to require mandatory assessment of aggressive dogs by veterinarians. In 2019, dogs reported as aggressive and considered a potential risk to public safety by city officials were scheduled for a mandatory behavioral assessment by a veterinarian. For the purpose of this study, only aggressive dogs that had bitten (N = 65) were included. The goals were to better describe the aggressive behavior of these dogs (behavioral sequence, type of aggression, and overall reactivity) and perhaps identify new possible risk factors related to severity of injury and dangerousness. The number of signs of increased arousal/reactivity was positively and significantly associated with the injury severity score. Dangerousness increased with size of dogs. Entire males were most dangerous despite absence of recognizable differences in body weight between neutered and unneutered males.     

Assessment of serotonin in serum,plasma, and platelets of aggressive dogs

Canine aggression is the most common reason for the referral of dogs to behavior practices. In addition, dog bites represent an important problem for public health and animal welfare. The serotonergic system is believed to play an important role in modulating aggression. The aim of the present study was (1) to assess the suitability of different types of blood samples for measuring circulating serotonin in canine clinical studies, and (2) to investigate the relationship between the serotonergic system and canine aggression. The assessment of serotonin was simultaneously carried out in serum, plasma, and platelets of 28 aggressive and 10 nonaggressive dogs with an enzyme immunoassay technique. The mean serotonin concentration in aggressive dogs was significantly lower than in nonaggressive dogs in all the assayed samples. These findings suggest an inverse relationship between the activity of the serotonergic system and canine aggression. Considering the simplicity of the methodology, the authors propose sampling serum as the most suitable method for measuring circulating serotonin in dogs.