Relationship between aggressive and avoidance behaviour by dogs and their experience in the first six months of life

The early experiences of dogs showing signs of avoidance behaviour or aggression were compared with those of dogs from the same clinical population that did not show such behaviour. The occurrence of each behavioural sign was tested for its association with the dog's maternal environment, the environment it experienced between three and six months of age, and the age at which it had been acquired. Non-domestic maternal environments, and a lack of experience of urban environments between three and six months of age, were both significantly associated with aggression towards unfamiliar people and avoidance behaviour. Aggression during a veterinary examination was more likely in dogs from non-domestic maternal environments. There was no significant association with either environment for aggression towards familiar people, or towards 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.     

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.     

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.     

Effects of lithium on aggressive behaviour in domestic pigs

Lithium carbonate (0.75 and 1 mEq/kg daily) mixed with food was chronically administered to growing pigs. Control animals received equivalent amounts of sodium carbonate. Added lithium decreased intra-group aggression occurring when access to food was restricted but did not prevent aggression and fighting observed after mixing pigs from different origins. The results are discussed in relation to the current interpretations of the psychopharmacological activity of lithium, and the prospective value of using lithium in pig intensive husbandry for controlling behavioural disorders is examined.     

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.     

Fear-related behaviour of dogs in veterinary practice

To investigate further the occurrence of fear-related behaviour in dogs in veterinary practice and to evaluate associated factors, 135 dogs were observed under practice conditions within the framework of a standardised test examination and the owners interviewed using a questionnaire. Most dogs exhibited fear reactions, particularly on the examination table, with 78.5% (106/135) categorised as ‘fearful’ based on their behaviour. Unlike weight and castration, age, gender and previous experience were significantly (P < 0.05) associated with fearful behaviour. Male dogs were significantly less ‘fearful’ than females and animals under <2 years were significantly less ‘fearful’ compared with older dogs. Those with only positive previous experiences in veterinary surgeries were significantly less ‘fearful’ than dogs that had a previous negative experience. Fear-related behaviour in veterinary practice is an issue of importance.     

Aetiology of separation-related behaviour in domestic dogs

A longitudinal study of seven litters of labrador retrievers and five litters of border collies from eight weeks to 18 months of age indicated that the majority showed some degree of potentially undesirable behaviour when separated from their owners. Its incidence was particularly high in the labrador retrievers, of which 13 of 23 showed separation-related behaviour for more than a month. Socially diverse environments experienced between six and 12 months of age were associated with a subsequent absence of separation-related behaviour. In a questionnaire survey of dog owners, separation-related behaviour was reported in 27 of 94 dogs, and a further 20 had shown the behaviour in the past. Male dogs were more likely to express separation-related behaviour currently, and females were more likely never to have displayed it. The prevalence of the behaviour was unaffected by whether the dog was pedigree or mixed breed, or whether it had been obtained from a breeder or from a rescue organisation. Combining the results of the two studies, the owners of only six of 75 dogs showing separation-related behaviour had sought assistance, and only two of the owners had sought help from veterinary surgeons.