Patterns of mandibular asymmetries in two types of companion rabbits.

Developmental instability hypothesis suggests that asymmetric variation can partially reflect the body's inability to buffer environmental and/or genetic perturbations. Fluctuating asymmetry (FA), that is random differences between the left and right sides of body features that are symmetric at the population level, can assess this approach. Another kind of asymmetry is directional asymmetry (DA) which appears when the left and right sides differ consistently from each other. Extreme selection for morphological traits, as appear in some companion rabbits selected for a paedomorphic (dwarf rabbits) or gerontomorphic (belier rabbits) appearance, may cause abnormal functional conditions, which in turn could be expressed as significative degrees of asymmetries. To study these phenomena, we analysed 62 mandibles of companion rabbits (20 beliers and 42 dwarfs) by means of geometric morphometric methods and quantified their size and shape asymmetric variation (both FA and DA) using 18 landmarks on the lateral side. FA was present in both types but in different degrees, being higher among dwarfs. It is considered that this type is subject to deeper changes than among beliers, and therefore, there is higher pressure on the phenotype. This observation could be assumed to be an adaptive response, coming out as FA. The presence of DA was significative and similar for two types. This likely indicates common masticatory lateralization, a pattern that has been detected in other domestic mammals. The methodological framework presented in this study can be valuable for future works focused on genetically and/or environmentally related form study in pets.

Evaluation of a low-technology system to obtain morphological and mobility trial measurements in dogs and investigation of potential predictors of canine mobility.

OBJECTIVE: To develop a low-technology system that can be used by dog owners to obtain morphological and mobility measurements in companion dogs as candidate components of an eventual canine frailty scale. ANIMALS: 57 adult (≥ 1-year-old) dogs enrolled by 43 owners. PROCEDURES: Morphological measurements of dogs were performed by investigators and dog owners. Dogs participated in timed in-clinic mobility trials across a flat surface (on-leash trial with the owner, on-leash trial with the investigator, and off-leash trial) and on stairs; each trial was repeated 3 times. Owners were asked to conduct a second stair trial at home 2 weeks later. Agreement between owner- and investigator-obtained measurements was assessed with Shrout-Fleiss intraclass correlation coefficients and paired t tests. Age, quartile of projected percentage of mean life span attained (adjusted for body weight), and height were evaluated as predictors of speed and stride length in mobility trials with linear regression and Spearman rank correlation analysis. RESULTS: Agreement between owner- and investigator-obtained morphological measurements was strong. Age was a weak but significant predictor of decreased dog speed in mobility trials (adjusted R2, 0.10 to 0.23). Speed decreased significantly with increasing quartile of projected life span attained. A linear regression model that included height and age predicted dog speed better than models with age or height alone. CONCLUSIONS AND CLINICAL RELEVANCE: Morphological and mobility trial measurements can be obtained by dog owners with minimal training. Low-technology measurements of mobility trial speed offer potential as components in a future scoring scale for canine frailty.

The genetic basis of size in pet dogs: The study of quantitative genetic variation in an undergraduate laboratory practical.

The teaching of quantitative genetic variation in the undergraduate laboratory practical environment can be difficult as, for quantitative phenotypes that are under the control of multiple loci, detection of phenotypic differences caused by individual variants is problematical without large samples, impractical in such classes. Pet dogs provide a clear example of quantitative genetic variation with individual breeds ranging in size from 1 to 70 kg weight yet with little intrabreed variability. In contrast to humans where there are few identified genetic variants known to be involved in the genetically controlled size phenotype, in dogs, seven single nucleotide polymorphisms (SNPs) in six genes have been demonstrated to explain half of the phenotypic variance. In the practical described here, a single G-A SNP (within intron 2 of the insulin-like growth factor 1 gene) is studied through PCR, sequencing, and bioinformatics. Average breed weight of dogs of different genotypes at this SNP show significant differences in size (median [IQR] of AA = 10 kg [6-15 kg], AG = 23.75 kg [14-30 kg], GG = 30 kg [24.5-37 kg] from our class data) with an estimate of just ≈N = 16 dogs needing to be genotyped to demonstrate a significant difference in size between dogs harboring the two homozygous genotypes. In the practical described herein, from a single laboratory and a single computer session, students are able to see the clear effect of genotype on a quantitative trait. Examination of the variant in the Ensembl browser (www.ensembl.org) allows students to understand the genomic basis of this variant and appreciate the wealth of data and information publicly available in genome browsers. © 2018 International Union of Biochemistry and Molecular Biology, 46(6):623-629, 2018.

Going cheap: determinants of bird price in the Taiwanese pet market.

BACKGROUND: International wildlife trade is the largest emerging source of vertebrate invasive alien species. In order to prevent invasions, it is essential to understand the mechanics of trade and, in particular, which traded species are most likely to be released or escape into the wild. A species' economic value is a key factor, because we expect cheaper species to be less assiduously secured against escaping, and more likely to be deliberately released. Here, we investigate determinants of the price of species in the Taiwanese bird trade. Taiwan is an international hub for bird trade, and several native species are threatened by alien bird species. METHODOLOGY: We investigated the relationship between the traded species sale price in Taiwan and the species availability for trade (the number of birds for sale, geographic range size and their origin, conservation and CITES status) and traits (body size, coloration, song attractiveness). We used phylogenetic generalized least squares models, with multi-model inference, to assess the variables that are best related to the price of birds in the Taiwanese pet trade. PRINCIPAL FINDINGS/CONCLUSIONS: We found that species available for sale in larger numbers, native to Taiwan, not globally endangered, and small-bodied are all relatively cheaper, as too are species lacking yellow coloration and without attractive songs. Our models of price revealed high levels of phylogenetic correlation, and hence that closely related species tended to be sold for similar prices. We suggest that, on the basis of price, native species are more likely to be deliberately or accidentally released than alien species. Nevertheless, our survey of bird shops recorded 160 species alien to Taiwan (7,631 individuals), several of which are for sale cheaply and in large numbers. Alien bird species in trade therefore present an ongoing, non-trivial invasion risk on the island.

Invited review-Computed tomographic angiography (CTA) of the thoracic cardiovascular system in companion animals.

Computed tomographic angiography (CTA) of the thoracic cardiovascular system is offering new diagnostic opportunities in companion animal patients with the increasing availability of multidetector-row computed tomographic (MDCT) units in veterinary facilities. Optimal investigation of the systemic, pulmonary, and coronary circulation provides unique challenges due to the constant movement of the heart, the small size of several of the structures of interest, and the dependence of angiographic quality on various contrast bolus design and patient factors. Technical and practical aspects of thoracic cardiovascular CTA are reviewed in light of the currently available veterinary literature and future opportunities given utilizing MDCT in companion animal patients with suspected thoracic cardiovascular disease.

Brachycephalic airway syndrome.

Brachycephalic airway syndrome is a common finding in brachycephalic breeds. A combination of primary and secondary changes can progress to life-threatening laryngeal collapse. Early recognition of primary anatomic abnormalities that include stenotic nares, elongated soft palate, and hypoplastic trachea would allow the clinician to make early recommendations for medical and surgical management, which can improve the quality of life in affected animals.

Effects of phenotypic characteristics on the length of stay of dogs at two no kill animal shelters.

Adoption records from 2 no kill shelters in New York State were examined to determine how age, sex, size, breed group, and coat color influenced the length of stay (LOS) of dogs at these shelters. Young puppies had the shortest length of stay; LOS among dogs increased linearly as age increased. Neither coat color nor sex influenced LOS. Considering only size classifications, medium-size dogs had the greatest LOS, and extra small dogs and puppies remained in shelters for the least amount of time. Considering only breed groupings, dogs in the guard group had the greatest LOS and those in the giant group had the shortest LOS. The lack of effect of coat color was not expected, nor was the shorter LOS among "fighting" breeds compared with other breed groups. Coat color and breed may have only local effects on LOS that do not generalize to all shelters, including traditional shelters. Understanding the traits of dogs in a specific shelter and the characteristics of these nonhuman animals desired by adopters are critical to improving the welfare of animals served by that shelter.

Allometric study on the relationship between the growth of ovarian follicles and oocytes in domestic cats.

The relationship between the growth of preantral and antral follicles and that of their oocytes in ovaries of domestic cats (Felis catus) was analyzed. Eight hundred and five pairs of follicles and oocytes from the ovaries of 51 female cats were collected, and only healthy and fresh follicles and oocytes with or without zona pellucida were used in this study. Immediately after collection, the diameters of follicles and their oocytes were measured. The relationship of the follicle diameter to the oocyte diameter was applied to four regression models and statistically analyzed. The best fitting model was found to be a hyperbolic regression (the coefficient of determination was 0.976 between the follicles and their oocytes with a zona pellucida, y=184x/(x+0.0738); the coefficient of determination was 0.983 between the follicles and their oocytes without a zona pellucida, y=122x/(x+0.0301)). The differentiated equations for the hyperbolic curves in the oocytes with or without a zona pellucida and the follicles were found to be y'=13.6/(x+0.0738)² and y'=3.67/(x+0.0301)², where y and x were the diameters of the oocytes (µm) and follicles (mm), respectively. When follicles grew to a size larger than 0.4 mm in diameter, the growth rates of their oocytes calculated by the differentiation equations showed an asymptotic depression around zero. Thus, it was suggested that when the follicles grew to a size larger than 0.4 mm in diameter, their oocytes reached full size and ceased to grow and that the zona pellucida stopped growing when the diameter of the follicles reached 0.3 mm in domestic cats.