Temperament and lateralization in the domestic dog (Canis familiaris)

The authors investigated the relationship between paw preference (the paw with which dogs prefer to hold a food object) and temperament in the domestic dog (Canis familiaris). Hypotheses were based on the Valence-Specific Hypothesis, which broadly states that negative emotions are associated with the right hemisphere, and positive emotions are associated with the left hemisphere. To assess each dog's temperament, an owner-rated temperament questionnaire was administered to the owners of 73 pet dogs. The same dogs were tested for paw preference using a Kong (KONG Company, Golden, CO) stuffed with food and were subsequently classified as left-pawed, right-pawed, or ambilateral. A laterality index (LI) value was also calculated for each dog in the study to provide an indication of the strength and direction of its paw preference. Positive LI values reflected a preference for the right paw, whereas negative LI values reflected a preference for the left paw. The LI ranged from ?100 to +100, with numbers closer to either extreme reflecting a stronger paw preference and a score of 0 indicating no preference. The absolute value of LI reflects the strength, but not direction, of paw preference and was included in some analyses.We found no evidence to support a relationship between paw preference and temperament, with the exception that lateralized dogs scored marginally higher than ambilateral dogs on a measure of stranger-directed aggression. We suggest that the temperament assessment used in this study may not be sensitive enough to detect differences between individuals based on their lateralization. Temperament factors were also compared with a number of “demographic” variables (e.g., age, sex, whether the dog was a purebred or a crossbreed, and the frequency of exercise) to determine the effect of these variables on temperament outcomes.     

Lack of standardization in reporting motor laterality in the domestic dog (Canis familiaris)

Over the past 2 decades, numerous studies have been undertaken to assess motor laterality in the domestic dog. In anticipation of growth in this area of enquiry, we decided to review the literature on canine motor biases to identify any shortcomings, reflect on the lessons to be learned from and offer ways forward for future research into canine laterality. The aim of this review is to (i) summarize motor laterality findings in the dog, (ii) highlight areas lacking in standardization, and (iii) propose necessary criteria for future tests and global reporting protocols. Our review of the literature highlighted the lack of standardization between studies in task selection, sample size, number of behavior scores recorded, and the methods by which motor laterality were classified and reported. This review illustrates the benefits of standardizing methods of motor laterality assessment so that comparisons can be made between the populations sampled. By adopting such an approach, researchers should mutually benefit as motor laterality data could then be compared and subjected to meta-analysis.     

Structure and ultrastructure of the celiac-mesenteric ganglion complex in the domestic dog (Canis familiaris)

A number of neurons of the autonomic nervous system are situated in the ganglia and can be systematically divided into pre-vertebrals, paravertebrals, intramural and para-viscerals. The celiac-mesenteric ganglion, an important pre-vertebral ganglion, is located together with the abdominal aorta and links the central nervous system to the peripheral system, participating in the coordination of peripheral reflexes and principally innervating the stomach, intestines, accessory glands (liver and pancreas). In addition, the celiac-mesenteric ganglion also contributes to the innervation of the spleen and has a role in gastrointestinal motility control. This study examined the structural and ultrastructural aspects of 40 celiac-mesenteric ganglia from domestic dogs. For light microscopy ganglia were included in paraplast and stained with haematoxylin-eosin, picrosirius, toluidine blue, Calleja's and Masson's trichrome. For examination by electron microscopy, the ganglia were submitted to cryofracture, enzyme digestion, hydrolysis and fixed in 5% glutaraldehyde in 0.1 M phosphate buffer (pH 7.4). The celiac-mesenteric ganglion was observed as a ganglionic complex composed of various ganglionic units separated by types I and III collagen fibres, predominantly unmyelinated nerve fibres and continuous capillaries. This complex is surrounded by a double-layer capsule (internal and external). The principal ganglion cells had eccentric nuclei with two nucleoli, the nucleolemma was double and presented nuclear pores. In the cytoplasm there were vesicles of the Golgi apparatus, electron-dense vacuoles, mitochondrias, smooth and granulated endoplasmic reticulum and free ribosomes. In conclusion, this ganglionic complex, in contrast to similar structures in the enteric nervous system, presents separate ganglionic units in a systematic arrangement related to the extrinsic and specific innervation of the target organs.     

Comparison of 3 different reinforcements of learning in dogs (Canis familiaris)

Effective dog training involves reinforcement of the dog's correct actions in response to specific cues given by the trainer. Food is usually selected as the primary reinforcer (reward), although this selection does not necessarily account for the learning preferences of individual dogs. We evaluated the relationship between reward and learning efficiency. Fifteen dogs were allocated to 3 different reward groups (food, stroking, and praise) and trained by an identical process. The food reward was the only one that shortened the time taken for the response to the command to be completed. However, this difference occurred only in the early training stages and not later in the training process.     

Histological and ultrastructural studies on the coronary artery of adult domestic dog (Canis familiaris)

The objective of this work was to study the histological structure of the dog's coronary artery by light and transmission electron microscope (TEM). The coronary artery consisted of three tunics: tunica intima, tunica media and tunica adventitia. The tunica intima consisted of endothelium rested directly on internal elastic lamina without the subendothelial connective tissue layer. The tunica media were composed of smooth muscle fibres interspersed with few elastic and collagen fibres. The tunica adventitia consisted of collagen and elastic fibres intermingled with fibroblast cells; it had vasa vasorum and nervi vasorum. Some histomorphometric measurements were performed and compared statistically. The ultrastructural study showed that the endothelial cells were communicated through complex junctions and characterised by filiform cytoplasmic processes passed through the opening of the underlying internal elastic membrane. The smooth muscle fibres of tunica media communicated with each other through cytoplasmic processes. The tunica adventitia showed minute non-myelinated nerve. This work revealed that the dog's coronary arteries are typical muscular arteries, which show little structural variations from that of other mammals.     

Life cycle of Isospora burrowsi n sp (Protozoa: Eimeriidae) from the dog Canis familiaris

Exogenous and endogenous stages of Isospora burrowsi n sp from the dog are described. Oocysts were spherical or ellipisoidal and 17 to 22 by 16 to 19 micrometer (mean 20.3 by 17.3 micrometer). Micropyle, oocyst residuum, and polar granule were not present. Sporocysts were 12 to 16 by 8 to 11 micrometer (mean 14.4 by 9.7 micrometer). Stieda body was absent, but a sporocyst residuum was present. Endogenous stages were in the caudal three-fifths of the small intestine and in the cecum. Mature 1st-generation schizonts (11 to 18 by 9 to 18 micrometer) were present on the 4th day of infection. One day later, mature 2nd-generation schizonts (18 to 35 by 17 to 22 micrometer) were present. Immature gamonts were found 5 days after infection, and unsporulated oocysts were also present later that day. The prepatent period was 6 days, and the mean patent period was 11 days. The oocysts of I burrowsi differ markedly in size from all other Isospora species from dogs, except Isospora ohioensis; however, the endogenous stages of the 2 species differ.     

Multiple ventricular bands and the associated trabecula septomarginalis dextra in the right ventricle of the domestic dog (Canis familiaris)

Ventricular bands are strand‐like intraventricular structures extending between adjacent papillary muscles; a papillary muscle and the ventricular wall or the interventricular septum and ventricular wall. Examination of the domestic dog right ventricle documented six ventricular band types. Eighty‐five of the 89 examined hearts had at least one right ventricular band. In the current study, the right ventricle of the 85 dog hearts was re‐examined for more than one ventricular band type. Seven patterns of multiple different bands were identified in the 24 dog hearts. The patterns (i.e., combinations) of different ventricular bands were grouped into three categories. Category 1 had five different patterns of bands. Each pattern had two different band types. Category 2 had one combination of three different bands. Category 3 had one combination of four different bands. The presence of right ventricular bands around the trabecula septomarginalis dextra was also documented. All 24 dog hearts with multiple ventricular bands had a trabecula septomarginalis dextra. The main goal of this study was documentation of multiple right ventricular band patterns. A secondary goal was documentation of the combined presence of these bands and a trabecula septomarginalis dextra. In the dog, the ventricular bands and trabecula are both thin, strand‐like intraventricular structures with variable branching patterns before blending into the ventricular wall. The gross similarity of these structures and lack of information on their combined presence could precipitate their misidentification.     

Anatomy of the Ductus Venosus in Neonatal Dogs (Canis familiaris)

Anatomical features of the ductus venosus in 84 neonatal dogs are described. The ductus venosus was a straight conduit 1–3 mm wide and 4–12 mm long in pups with a crown-rump length of 80–200 mm. It arose from the left main portal vein branch opposite the umbilical vein, passed between the left lateral liver lobe and the papillary process of the caudate lobe, and terminated in the dorsal aspect of the proximal part of the left hepatic vein. The left hepatic vein was dilated at this point. There was no variation in the location of the ductus venosus in the animals studied.     

Lateralization in the domestic dog (Canis familiaris): Relationships between structural,motor, and sensory laterality

Several studies have assessed different components of lateralization. To date, the relationships between the 3 measures of laterality, structural, motor, and sensory, have not widely been assessed. Specifically, the relationships between structural (hair whorl characteristics) and motor or sensory lateralization have largely been overlooked. This study investigated the associations between these measures of lateralization in dogs (n = 114), using hair whorl characteristics (structural), the Kong and First-stepping Tests (motor), and the Sensory Jump Test (sensory). Several associations emerged, revealing the first evidence of a relationship between structural asymmetry (both the presence and direction of a hair whorl in various regions of the body) and sensory lateralization. Specifically, the presence of a whorl on the dog’s left side of the head (cephalic) and thorax was associated with a right visual bias. In addition, right visual bias was probable if the ventral mandibular whorl was present in a counter-clockwise direction (P = 0.008). Our data also demonstrated an association between structural and motor laterality (paw preference). Most notably, dogs with clockwise chest whorls were significantly more right-preferent in the First-stepping Test than those with counter-clockwise whorls (P = 0.010). In addition, an association between measures of motor and sensory lateralization also emerged, representing some of the first evidence of such a relationship in nonhuman animals.     

Anatomic Observations of the Coronary Sinus in the Dog (Canis familiaris)

The coronary sinus was investigated in 34 normal adult dogs, in order to verify its formation, tributaries, length and the valves, as well as the relationship of the venous walls to the epicardium and to the myocardium. The valve of the coronary sinus was observed in only 4 cases (1.7 %). In 30 cases (98.3 %) the ostium of the coronary sinus was lacking a valve. The valve of Vieussens double, was found at the level of the transition between the great cardiac vein and the coronary sinus, as well as others parietal venous valves. A comparison with the human pattern was made, particularly regarding the action of the valve of the coronary sinus and the formation of the sinus.     

The effect of feeding different protein-free diets on the recovery and amino acid composition of endogenous protein collected from the distal ileum and feces in pigs

Nine barrows with an average initial weight of 60 kg were fitted with simple T-cannulas at the distal ileum. The animals were fed four different protein-free diets according to an incomplete latin square design. Diet 1 (control diet) consisted of 79.7% cornstarch, 10% sucrose, 3% Alphafloc (a source of cellulose), 3% canola oil and a vitamin-mineral premix. Diets 2, 3 and 4 contained, respectively, 4% pectin, an additional 7% cellulose and an additional 10% canola oil, each included at the expense of cornstarch. Feces were collected during 3 d following a 7-d adaptation period. Thereafter, digesta were collected during two 24-h periods with a 24-interval between periods. The pigs were fed 800 g of feed twice at 0800 and 2000. Added pectin increased (P less than .05) the recovery of endogenous protein in ileal digesta from 19.8 diet (diet 1) to 24.0 g per kg dry matter intake. This increment was largely due to increases (P less than .05) in glycine and proline from 1.9 to 2.4 and from 6.2 to 8.4 g per kg dry matter intake, respectively. In feces, only added cellulose increased (P less than .05) excretion of endogenous protein (8.4 vs 11.1 g/kg DM intake) and of most amino acids. Including additional fat did not affect the quantity of endogenous protein and amino acids recovered in ileal digesta or feces. Small but significant differences (P less than .05) were observed in the amino acid composition of endogenous protein recovered in ileal digesta when the different protein-free diets were fed.(ABSTRACT TRUNCATED AT 250 WORDS)     

Morphology and Classification of Right Ventricular Bands in the Domestic Dog (Canis familiaris)

Ventricular bands, also designated as ‘false tendons’, are described as single or multiple strands that cross the ventricles and have no connection to valvular cusps. Previous work indicates these strands are present in the ventricles of humans and some animal hearts and not always associated with cardiac pathologies. Despite these previous studies, the published literature is limited in documenting the morphology of these strands and incidence in animals. In this study, examination of 89 hearts showed six types of ventricular bands in the right ventricle of the domestic dog. These bands were classified according to their prevalence and points of attachment. Type I extended from the interventricular septum to the ventricular free wall, type II connected a musculus papillaris parvus to the ventricular free wall and type III connected trabeculae carneae on the interventricular septum. Type IV connected the trabeculae carneae on the ventricular free wall, type V interconnected papillary muscles and type VI connected the interventricular septum to a papillary muscle. While the study of these ventricular bands provided additional information on the cardiac anatomy of the domestic dog, it also showed their clinical importance. Several studies have proposed that their position in the ventricle may interfere with cardiac catheterization and pacemaker lead placement or be misinterpreted during echocardiography.     

A double-blind placebo-controlled study into the efficacy of a homeopathic remedy for fear of firework noises in the dog (Canis familiaris)

Seventy-five dogs that showed a fear response to fireworks participated in a double-blinded, placebo-controlled clinical trial to assess the efficacy of a homeopathic remedy for the alleviation of their behavioural signs. Dogs were randomly assigned to one of two treatments; the homeopathic treatment or the placebo treatment. At the baseline assessments the owners identified the behavioural signs of fear that their dogs normally displayed in response to fireworks, rated their frequency and intensity, and assessed the global severity of their dog's responses. These measures were repeated at the final assessment and owners also completed weekly diaries for the length of the trial. There were significant improvements in the owners' rating of 14/15 behavioural signs of fear in the placebo treatment group and all 15 behavioural signs in the homeopathic treatment group. Both treatment groups also showed significant improvement in the owners' rating of the global severity of their dog's responses. However, there was no significant difference in the response seen between the two treatment groups.     

同位素标记内源氮法测定回肠内源氨基酸排泄量研究进展

内源氨基酸排泄量(LEAA)是测定饲料氨基酸真消化率的重要指标,而同位素标记内源氮法是直接测定内源氨基酸排泄量的有效方法之一。本文综述了同位素标记内源氮法测定回肠内源氨基酸排泄量的基本原理、假设条件和影响因素。