Chewing asymmetry in dogs: Exploring the importance of the fossa masseterica and first molar teeth morphology.

Dogs are animals with strong bite force. This strong bite mechanism has led to significant changes in the skeletal system such as fossa masseterica. It can be thought that one side is used more than the other side in chewing and is related to the preference of using the same side's hand, eye and foot. In the study, directional asymmetry and fluctuating asymmetry, which occurs as a result of chewing asymmetry, were examined on the first molar teeth and the fossa masseterica in 85 dog mandibles including a wide diversity of morphotypes. The association of high PC1 values for directional asymmetry with a pronounced cranial index, as evident in breeds like Pekingese, Pomeranian and Bulldog, indicates a potential evolutionary or selective breeding trend favouring brachycephaly. On the contrary, guardian breeds like the German shepherd and Bernese mountain dog, which typically require strong jaws for their roles, showcased reduced PC1 values, which might be related to their functional morphology. Similarly, the PCA results for the first molar teeth shape variations also highlighted the influence of cranial shape, with boxer dogs displaying notably higher PC1 values. The fluctuating asymmetrical distributions provided valuable insights into individualistic variations. Interestingly, no specific breed distribution trend was observed for these asymmetries, indicating a more individual-based variation rather than breed-based. It is essential to note that while these results provide valuable insights, further studies are required to understand the underlying causes better. Factors like genetic variations, developmental processes, dietary habits and external environmental factors could play pivotal roles in these observed morphological differences.

Reference intervals for various measurements of canine left atrial size and function obtained using two-dimensional and three-dimensional echocardiography.

BACKGROUND: Many canine cardiac diseases are associated with left atrial (LA) remodeling and decreased function. For accurate assessment of LA indices, large-scale and prospectively determined reference intervals are necessary. OBJECTIVES: To generate reference intervals of LA size and function using two-dimensional and three-dimensional echocardiography. ANIMALS: Two hundred and one healthy adult dogs. METHODS: Left atrial volume was assessed in right parasternal long-axis, left apical four-chamber and two-chamber views using monoplane Simpson's method, two-dimensional and three-dimensional speckle tracking. Additionally, LA diameter was measured in right parasternal short-axis and long-axis views. Furthermore, LA function was determined by measuring strain and calculating LA fractional shortening and ejection fraction. All variables were tested for correlation to heart rate, age, and body weight. For LA diameter and volume, scaling exponents and prediction intervals were generated using allometric scaling. Reference intervals for LA function parameters were calculated using nonparametric methods. RESULTS: Left atrial diameter and volume showed a strong correlation with body weight. The scaling exponent for LA diameter was approximately 1/3 (0.34-0.40) and approximately one for volume measurements (0.97-1.26). Parameters of LA function showed no clinically relevant correlation with body weight, except for two variables, which showed a mild negative correlation. No clinically relevant correlations with age or heart rate were found. CONCLUSIONS: Reference intervals for linear, two-dimensional and three-dimensional measurements of LA size and function were established. The wide range of measurement methods offers the opportunity to select the appropriate reference values for LA evaluation depending on the available technical possibilities.

Vertebral heart size and vertebral left atrial size reference ranges in healthy Miniature Schnauzers.

OBJECTIVE: The inclusion of vertebral heart score (VHS) and, more recently, the inclusion of the vertebral left atrial size (VLAS) in radiographic evaluation have become important screening tools for identifying dogs with occult cardiac disease. Several recent papers have shown there are interbreed variations in the VHS reference range. Our hypothesis is that the Miniature Schnauzer would also have a higher reference range for its VHS. ANIMALS: The electronic medical records of IDEXX Telemedicine Consultants were searched for Miniature Schnauzers undergoing thoracic radiographs between March 1, 2022, and February 28, 2023. METHODS: Dogs were included if they had 3 view thoracic radiographs performed and no evidence of cardiopulmonary disease was detected. Dogs with incomplete radiographic studies or cardiac or extracardiac disease were excluded. The VHS and VLAS measurements were performed by 2 board-certified cardiologists independent of one another. RESULTS: A total of 1,000 radiographs were obtained of which 272 were included for the study. The overall range for the VHS in this cohort was 9.68 to 12.07 with a median of 10.9. For VLAS measurements, a range of 1.71 to 2.4 was documented with a median of 2.0. CLINICAL RELEVANCE: The VHS for Miniature Schnauzers without cardiac disease was confirmed to be higher than the canine reference range.

Computer tomography measurements of the airway and thoracic cavity do not provide support for bronchial conformation as a predisposing factor of left cranial lung lobe torsion in pugs.

The objective of this retrospective clinical study was to determine if airway or thoracic cavity measurements in pugs, particularly the left cranial lung lobe, were significantly different from brachycephalic and mesocephalic control. Thoracic computed tomographic studies of 10 pugs, French bulldogs (FB), and Jack Russell Terriers (JRT) were analyzed. Thoracic height: width ratio (H:W), cross-sectional areas of the left mainstem bronchus (CSA LMB), left cranial lung lobe bronchus (CSA LCrBr), left caudal lung lobe bronchus (CSA LCauBr), CSA LCrBr relative to length (CSA LCrBr/length) and CSA LCauBr/length were measured and adjusted to body weight (/kg). CSA LMB/kg, CSA LCauBr/length/kg, and CSA LCrBr/length /kg were smaller in pugs and FB compared with JRT (P < .05), but no differences were found between pugs and FB. Cross-sectional areas of left cranial lung lobe bronchus /kg and CSA LCauBr/kg were smaller in pugs than JRT (P < .05), but no differences were found between pugs and FB or FB and JRT. No difference was found in thoracic H:W between any breeds. This demonstrated that pugs and FB had significantly narrower bronchi CSA/lengths ratios compared with JRT, but this was not limited to the LCBr. Airway measurements were not significantly different between brachycephalic breeds; therefore, the pugs' predisposition to left cranial lung lobe torsion cannot be solely explained by narrower lower airways.

Implantation Corridors in Canine Thoracic Vertebrae: A Morphometric Study in Dogs of Varying Sizes.

OBJECTIVE: Surgical stabilization to treat fractures, luxations, and congenital malformations in the thoracic spine can be difficult due to its unique anatomy and surrounding structures. Our objective was to document the morphometrics of the thoracic vertebrae relating to an ideal trajectory for dorsolateral implant placement in a variety of dog sizes and to assess proximity to important adjacent critical anatomical structures using computed tomography (CT) studies. STUDY DESIGN: Medical records for 30 dogs with thoracic CT were evaluated. Implantation corridor parameters for thoracic vertebrae (T1-T13) were measured, including the length, width, angle from midline, and allowable deviation angle for corridors simulated using an ideal implant trajectory. The distances from each vertebra to the trachea, lungs, aorta, subclavian artery, and azygos vein were also measured. RESULTS: Implantation corridor widths were often very narrow, particularly in the mid-thoracic region, and allowable deviation angles were frequently small. Distances to critical anatomical structures were often less than 1 mm, even in larger dogs. CONCLUSION: Thoracic implantation requires substantial precision to avoid breaching the canal, ineffective implant placement, and potential life-threatening complications resulting from invasion of surrounding anatomical structures.

Ultrashort Echo Time Quantitative Magnetic Resonance Imaging of the Cruciate Ligaments in Normal Beagles.

OBJECTIVE: The aim of this study was to provide normative ultrashort echo time magnetic resonance imaging (UTE MRI) data of the patellar ligament (PL), cranial cruciate ligament (CrCL) and caudal cruciate ligament (CdCL) in non-lame Beagles. STUDY DESIGN: Eight stifles from four subjects obtained immediately postmortem were imaged using UTE MRI in the true sagittal plane. Regions of interest were drawn manually and the total (T2*), short T2* (T2*S) and long T2* (T2*L) values of the signal decay were calculated to evaluate the bound and free water components of the tendon. The T2*S, T2*L and T2* values were compared between the PL, CrCL and CdCL RESULTS: The mean and standard deviation of T2*S, T2*L and T2* were as follows: 0.54 ± 0.13, 4.65 ± 1.08 and 8.35 ± 0.82 ms for the PL; 0.46 ± 0.14, 5.99 ± 0.52 and 8.88 ± 0.4 ms for the CrCL and 0.41 ± 0.13, 7.06 ± 0.57 and 9.26 ± 0.18 ms for the CdCL. Significant differences were found between the T2*L component of the PL and each CrCL/CdCL and a smaller difference was noted between the T2*L of the CrCL and CdCL (p = 0.05). No difference of the T2*S value was found between any of the ligaments. CONCLUSION: Establishing normative UTE data of the canine stifle is valuable for comparison in future studies in which normal and damaged ligaments may be evaluated, particularly in those affected limbs in which no instability is identified on physical examination in which normal and damaged ligaments may be evaluated.

The history of Coast Salish "woolly dogs" revealed by ancient genomics and Indigenous Knowledge.

Ancestral Coast Salish societies in the Pacific Northwest kept long-haired "woolly dogs" that were bred and cared for over millennia. However, the dog wool-weaving tradition declined during the 19th century, and the population was lost. In this study, we analyzed genomic and isotopic data from a preserved woolly dog pelt from "Mutton," collected in 1859. Mutton is the only known example of an Indigenous North American dog with dominant precolonial ancestry postdating the onset of settler colonialism. We identified candidate genetic variants potentially linked with their distinct woolly phenotype. We integrated these data with interviews from Coast Salish Elders, Knowledge Keepers, and weavers about shared traditional knowledge and memories surrounding woolly dogs, their importance within Coast Salish societies, and how colonial policies led directly to their disappearance.

​Comparative genomics of Balto, a famous historic dog, captures lost diversity of 1920s sled dogs.

We reconstruct the phenotype of Balto, the heroic sled dog renowned for transporting diphtheria antitoxin to Nome, Alaska, in 1925, using evolutionary constraint estimates from the Zoonomia alignment of 240 mammals and 682 genomes from dogs and wolves of the 21st century. Balto shares just part of his diverse ancestry with the eponymous Siberian husky breed. Balto's genotype predicts a combination of coat features atypical for modern sled dog breeds, and a slightly smaller stature. He had enhanced starch digestion compared with Greenland sled dogs and a compendium of derived homozygous coding variants at constrained positions in genes connected to bone and skin development. We propose that Balto's population of origin, which was less inbred and genetically healthier than that of modern breeds, was adapted to the extreme environment of 1920s Alaska.

Olfactory stimulus as environmental enrichment for shelter dogs: a pilot study / Estímulo olfativo como enriquecimento ambiental para cães de abrigo: um estudo piloto

Environmental enrichment techniques include olfactory stimuli for improving animal welfare. This study aimed to analyze the reactions of 41 shelter dogs exposed to odorous stimuli, such as the method used in another study on wild canids. The focal animal method analyzed the dogs' reactions, with all behaviors recorded. Behavioral responses were classified as positive (P+), negative (N-), or other (Ot). Independent variables were all dogs and the size of the packs. The behavior between the basal (without stimulus), exposure, and after-stimulus withdrawal was analyzed. For all dogs, olfactory stimuli significantly increased P+ (P=0.001) and N- (P=0.004), contrasting with the decrement of Ot behaviors (P=0.001) from the basal to the exposure phase. After the withdrawal of the stimuli, P+, N-, and Ot behaviors returned to basal levels (P>0.05). There were no significant differences (P>0.05) in the conduct of small or large packs exposed to stimuli. Dogs are sensitive to olfactory stimuli, but arousal is generalized to P+ and N-. It is undesirable to an N- increase for improvement of animal welfare. Contrary to what was observed in a study with wild canids, the method failed in shelter dogs because N- was increased. The introduction of sudden novelty (olfactory stimulus) in an impoverished shelter environment may have caused excitement in the dogs. It is suggested that changes in the method, such as stimuli exposition to each dog in an isolated room, are necessary to increase sheltered dog well-being.(AU)

As técnicas de enriquecimento ambiental incluem estímulos olfativos para aumentar o bem-estar animal. O objetivo deste estudo foi analisar as reações de 41 cães de abrigo expostos a estímulos odoríferos, como o método utilizado em outro estudo com canídeos selvagens. As reações dos cães foram analisadas pelo método animal focal, com todos os comportamentos registrados. As respostas comportamentais foram classificadas como positivas (P+), negativas (N-) ou outras (Ot). As variáveis independentes foram todos os cães e o tamanho das matilhas. Foi analisado o comportamento entre o basal (sem estímulo), exposição e após a retirada do estímulo. Para todos os cães, os estímulos olfativos aumentaram significativamente P+ (P=0,001) e N- (P=0,004), contrastando com a diminuição dos comportamentos Ot (P=0,001) da fase basal para a de exposição. Após a retirada dos estímulos, os comportamentos P+, N- e Ot retornaram aos níveis basais (P>0,05). Não houve diferenças significativas (P>0,05) no comportamento de matilhas pequenas ou grandes expostas a estímulos. Os cães são sensíveis a estímulos olfativos, mas a excitação parece ser generalizada para ambos, P+ e N-. É indesejável um aumento de N- para melhoria do bem-estar animal. Ao contrário do que foi observado em um estudo com canídeos selvagens, o método falhou em abrigar cães porque o N- foi aumentado. A introdução de uma novidade repentina (estímulo olfativo) em um ambiente de abrigo empobrecido, pode ter causado excitação exagerada nos cães. Sugere-se alterações no método, como a exposição de estímulos a cada cão em uma sala isolada necessária para aumentar o bem-estar do cão abrigado.(AU)

Anatomía clínica-quirúrgica del plexo venoso vertebral del perro: una revisión de la literatura / Clinical and surgical anatomy of the dog vertebral venous plexus: a literature review

El objetivo de la presente monografía, fue actualizar la anatomía del Plexo Venoso Vertebral (PVV) del perro de relevancia clínico-quirúrgica y asimismo evaluar el cumplimiento de la Nómina Anatómica Veterinaria (NAV). Se realizaron búsquedas electrónicas utilizando 9 bases de datos, donde se revisaron un total de 49 fuentes bibliográficas. De éstas, 20 correspondieron a artículos científicos. El criterio de exclusión fue el de publicaciones con más de 10 años de antigüedad, con excepción de libros de anatomía veterinaria de referencia base. Publicaciones que no estuvieran escritas en inglés, español o portugués, fueron también excluidas. En general, en la literatura revisada, existió consenso de cuáles son los componentes del PVV, junto con una escueta descripción de éste. El componente del PVV que es más ampliamente descrito y con mayor dimensión es el Plexo Vertebral Interno Ventral (PVIV). La función de retorno venoso sanguíneo alternativo hacia el corazón es la más nombrada. La no existencia de válvulas en el PVIV, pudiese ser una condición promotora para la metástasis tumoral a través del PVV. A nivel quirúrgico, la hemorragia del PVV, representa un peligro no despreciable para la vida del paciente. Con respecto a lo revisado y discutido, se puede concluir que: i) a pesar de la escasa descripción anatómica del PVV se pudo comprender cómo éste está compuesto ii) el nivel de evidencia que avala las distintas capacidades funcionales del PVV es bajo, no obstante, la información de la presentación de la hemorragia del PVV en las distintas cirugías es mayor iii) las variadas referencias bibliográficas consultadas no respetaron la NAV actual para describir al PVV.

SUMMARY: This monograph aims to provide an update on the anatomy of the Vertebral Venous Plexus (VVP) of the dog with emphasis on its clinical and surgical relevance and to evaluate compliance of terms in the literature with Nomina Anatomica Veterinaria (NAV). Electronic searches were conducted using 9 databases, where a total of 49 bibliographic sources were reviewed. Of these, 20 consisted of scientific articles. Publications with more than 10 years old were excluded from review, except for basic reference veterinary anatomy books. Publications that were not written in English, Spanish or Portuguese were also excluded. In general, in the literature reviewed, there was consensus on what the components of the VVP are, along with a brief description of VVP. The most widely described component of the VVP is the Ven- tral Internal Vertebral Plexus (VIVP). The function of alternative venous blood return to the heart is the most frequently described. The absence of valves in the VIVP could be a promoting condition for tumor metastasis through the VVP. At the surgical level, VVP hemorrhage represents a non-negligible threat to the patient's survival. With respect to what has been reviewed and discussed, it can be concluded that: i) despite the scarce anatomical description of the VVP, it was possible to understand how it is composed ii) the level of evidence that supports the different functional capacities of the VVP is low, however, the information on the ocurrence of VVP hemorrhage in surgical procedures is greater and iii) the various bibliographical references describing the VVP did not comply with the current NAV.

An anatomical training model for cerebrospinal liquid collection and myelography in embalmed dog cadavers / Modelo anatômico para treinamento de colheita de líquido cerebroespinhal e mielografia em cadáveres de cães quimicamente preparados

In research and academic activities, guidelines are essential and imperative especially on the use of animals. Alternative methods that do not bring academic or scientific harm should also be sought. This study aimed to develop a training model for the collection of cerebrospinal fluid (CSF) and myelography in the cervical and lumbar regions in cadavers of embalmed dogs, using an alcoholic solution and curing salts for fixation and conservation. The dogs were divided into 4 grups of 8 animal each and stored between 2ºC and 6ºC, for 30, 60, 90, or 120 days. Durotomy was performed to implant two urethral catheters (one in the cranial direction and another in the caudal direction to the spinal cord access site), in the subduraracnoid space. This space was fixed via manual infusion of saline solution with a 20-mL syringe to simulate the presence of the CSF and the positive pressure, while the puncture was made. Four cadavers of each group were randomly selected for the CSF puncture from the atlantooccipital joint and in the lumbar region between L5 and L6, respectively, and four were used for CSF puncture training, in which radiographic contrast (myelography) was injected in the same locations. This model was cost-effective, did not utilize toxic products, and can preserve cadavers for up to 120 days. In this novel anatomical model, a maximum of 15 students can be trained on CSF puncture, allowing cervical and lumbar myelography and at least 30 perforations per cadaver.

É essencial e imperioso ter critério quanto ao uso de animais em pesquisa e atividades de ensino e, consequentemente, buscar métodos alternativos que não causem prejuízo acadêmico ou científico. Para que não ocorra deterioração dos tecidos, a fixação e conservação de peças anatômicas e cadáveres devem ser realizadas. Objetivou-se, com este estudo, desenvolver um modelo anatômico para treinamento de colheita de líquido cerebroespinhal (LCE) e mielografia, nas regiões cervical e lombar. Os cães foram divididos em quatro grupos contendo oito animais cada e armazenados entre 2ºC e 6ºC, por 30, 60, 90 ou 120 dias. Foi realizada durotomia para implantação de duas sondas uretrais, no espaço subaracnóide. A infusão manual de solução fisiológica com seringa de 20 mL foi utilizada para simular a presença do LCE e a pressão positiva, enquanto era feita a punção. Quatro cadáveres de cada grupo foram selecionados para a punção de LCE na articulação atlantooccipital e na região lombar entre L5 e L6, e quatro foram utilizados para o treinamento da punção de LCE e injeção de contraste radiográfico (mielografia). A técnica anatômica empregada possibilitou o desenvolvimento de um modelo visando ao ensino e pesquisa da radiologia em cadáveres de cães quimicamente preparados, a custo baixo e sem utilização de produtos tóxicos, mantidos sob refrigeração por 120 dias. Com isso, um máximo de 15 alunos podem ser treinados em punção do LCR, permitindo mielografia cervical e lombar com 30 perfurações por cadáver.

Anatomic structures of the canine middle ear visible during endoscopic examination through a ventral or lateral approach.

OBJECTIVE: To describe the anatomic structures of the canine middle ear visible during endoscopic examination through ventral and lateral surgical approaches. SAMPLE: 5 cadaveric canine heads representing 4 breeds. PROCEDURES: A descriptive study was performed. For each head, a lateral approach was performed on one side and a ventral approach was performed on the opposite side. Images were obtained with a 2.7-mm, 30° telescope. RESULTS: Captured images were reviewed, and anatomic structures visualized through the lateral and ventral approaches were identified. The optimal approach, telescope position, and light post orientation to identify each anatomic structure were subjectively determined. CLINICAL RELEVANCE: Middle ear evaluation with a telescope was technically straightforward and allowed identification of middle ear structures not typically visible with an open surgical approach. Findings may serve as an anatomic reference guide for future video-assisted surgical procedures of the middle ear. A better understanding of the location of anatomic structures in the middle ear may help to prevent unnecessary damage to fragile middle ear structures, such as nerves or blood vessels, during surgical procedures.

Comparative analysis of origin and branches of phrenic nerve in the diaphragm of the crab-eating fox (Cerdocyon thous) and domestic dog (Canis lupus familiaris).

The crab-eating fox (Cerdocyon thous) is a canid widely distributed throughout South America, considered the only representative of the gender. There is a lack of information about anatomical aspects of the species, mainly regarded of nervous system anatomy. For clinical and surgical approaches of these animals, the domestic dog is adopted as anatomophysiological model. So, the aim of the present study was to analyse origin and branches of the phrenic nerve in the diaphragm of crab-eating fox compared to domestic dog. Four specimens of Cerdocyon thous and four of Canis lupus familiaris were used. The phrenic nerve originated from the ventral branches of the fifth (C5), sixth (C6) and seventh (C7) cervical spinal nerves. Phrenic nerves were distributed in the diaphragm as lumbocostal trunk and sternal branch (100%) in the crab-eating fox, and in costosternal trunk and lumbar branch (75%) and lumbocostal trunk and sternal branch (25%) in the domestic dog. In both species, the lumbar branch innervates the diaphragm pillars, the costal branch addresses all costal region, and the sternal branch distributes in the costal ventrolateral region and the sternal part of the diaphragm, to the left and to the right.

Variations in facial conformation are associated with differences in nasal microbiota in healthy dogs.

BACKGROUND: Extrinsic and intrinsic factors have been shown to influence nasal microbiota (NM) in humans. Very few studies investigated the association between nasal microbiota and factors such as facial/body conformation, age, and environment in dogs. The objectives are to investigate variations in NM in healthy dogs with different facial and body conformations. A total of 46 dogs of different age, living environment and from 3 different breed groups were recruited: 22 meso-/dolichocephalic medium to large breed dogs, 12 brachycephalic dogs and 12 terrier breeds. The nasal bacterial microbiota was assessed through sequencing of 16S rRNA gene (V1-V3 regions) amplicons. RESULTS: We showed major differences in the NM composition together with increased richness and α-diversity in brachycephalic dogs, compared to meso-/dolichocephalic medium to large dogs and dogs from terrier breeds. CONCLUSION: Healthy brachycephalic breeds and their unique facial conformation is associated with a distinct NM profile. Description of the NM in healthy dogs serves as a foundation for future researches assessing the changes associated with disease and the modulation of NM communities as a potential treatment.

High-definition ultrasonography in the evaluation of the reproductive tract of bitches during the follicular phase of the estrous cycle.

The aim was to sonographically evaluate the reproductive tract of bitches during the follicular phase of the estrous cycle using High Density (HD) ultrasonic techniques. Females (n = 8) were evaluated at five different times throughout the follicular phase, as determined by vaginal cytology and blood progesterone concentrations. Ultrasonic exams were performed using the ACUSON S2000/SIEMENS device utilizing a multifrequency HD transducer (5.5-18 MHz). Videos of the ovaries were obtained and recordings were evaluated using a DICOM viewer software for counting and measuring the ovarian structures, which were assigned to groups based on diameter in mm: G1: ≤ 1; G2: from 1.01 to 3.5; G3 from 3.51 to 5.5; G4: from 5.51 to 10. There was a greater uterine thickness with the progression of the follicular phase (P < 0.05). Six distinct regions were identified in the uterine wall. The ovarian dimensions increased (P < 0.05) as stage of the follicular phase advanced. There was fluid detected around the ovaries after ovulation. There was a characteristic fat tissue hyperechogenicity around the ovaries at all timepoints. There was a difference in the number of ovarian structures of each dimension group at each time there were assessments (P < 0.05). There was a difference in diameter of the largest ovarian structure and in average value of wall thickness at all timepoints when there were evaluations (P < 0.05). The HD ultrasonography technique provides for excellent image resolution, allowing for a more precise characterization of the bitch's reproductive structures and changes occurring during the follicular phase of the estrous cycle.

The PMEL gene and merle (dapple) in the dachshund: cryptic, hidden, and mosaic variants demonstrate the need for genetic testing prior to breeding.

One of the most unique coat color patterns in the domestic dog is merle (also known as dapple in the dachshund breed), characterized by patches of normal pigmentation surrounded by diluted eumelanin pigment. In dogs, this striking variegated pattern is caused by an insertion of a SINE element into the PMEL gene. Differences in the length of the SINE insertion [due to a variable-length poly(A)-tail] has been associated with variation in the merle coat color and patterning. We previously performed a systematic evaluation of merle in 175 Australian shepherds and related breeds and correlated the length of the merle insertion variants with four broad phenotypic clusters designated as "cryptic", "atypical", "classic", and "harlequin" merle. In this study, we evaluated the SINE insertions in 140 dachshunds and identified the same major merle phenotypic clusters with only slight variation between breeds. Specifically, we identified numerous cases of true "hidden" merle in dachshunds with light/red (pheomelanin) coats with little to no black/brown pigment (eumelanin) and thus minimal or no observable merle phenotype. In addition, we identified somatic and gonadal mosaicism, with one dog having a large insertion in the harlequin size range of M281 that had no merle phenotype and unintentionally produced a double merle puppy with anophthalmia. The frequent identification of cryptic, hidden, and mosaic merle variants, which can be undetectable by phenotypic inspection, should be of particular concern to breeders and illustrates the critical need for genetic testing for merle prior to breeding to avoid producing dogs with serious health problems.

Labial and buccal minor salivary glands of the dog - location, three-dimensional arrangement and histology.

OBJECTIVE: Transplantation of minor salivary glands (MSGs) to the conjunctiva is a treatment option for patients suffering from dry eye disease. As there is not enough information about labial and buccal MSGs in dogs, the aim of this study was to provide evidence of the presence of these glands and to investigate their spatial arrangement and excretory ducts. METHODS: The oral mucosa of the lower lip of 4 dogs and the whole lower jaw of 1 dog were used for histological and microCT analysis. Presence, number, volumes and the tissue depth of MSGs were assessed. RESULTS: Histological analysis showed that compact tubulo-acinar glands were located in the submucosal connective tissue. MicroCT images revealed that 9 to 21 MSGs were arranged in a single row at the level of the dental alveolae. The volume of the MSGs increased from rostral to caudal and the total volume of glandular tissue per animal ranged from 35.01 mm3 to 549.43 mm3 . The mean tissue depth of MSGs ranged from 0.57 mm to 1.37 mm (upper surface of glands) and between 1.43 mm and 3.09 mm (lower surface of the glands). Excretory ducts left the dorsal part of the glands and ran in dorso-rostral direction. CONCLUSIONS: The location, number and volume of the labial and buccal MSGs in the dog could be detected and described using microCT scans and histology. The present results can provide valuable information for future transplantation of labial MSGs as therapeutic measure against keratoconjunctivitis sicca.

Comparison of radiographic and computed tomographic acetabular index in small-breed dogs: a preliminary study using Maltese and Shih Tzu.

BACKGROUND: The morphometry of the acetabulum is one source of information that assists in the clinical diagnosis of the hip and influences the proper selection of a prosthesis, reducing post-operative complications such as those seen in total hip replacement (THR). However, acetabular parameters in small-breed dogs are rarely reported. OBJECTIVES: To investigate acetabular parameters using radiography and computed tomography (CT) in small-breed dogs with Maltese and Shih Tzu dogs used as model breeds. METHODS: Standard calibrated, extended hip radiographs and CT images were obtained. Subsequently, acetabular width (AW) in various directions was measured using radiography and CT, whereas acetabular depth (AD) was obtained by CT. Acetabular index (AI) is a ratio calculated from AD and AW. RESULTS: The values of AW and AD were much higher in Shih Tzu than in Maltese dogs. Male Shih Tzus showed higher values of these parameters than females, while sex-based differences in most of the parameters could not be detected in Maltese. Body weight, but not age, influenced AWs and ADs. While AWs and ADs were influenced by several factors, AI was comparable among the assessed factors and between Maltese and Shih Tzu dogs (p = 0.172; 31.42 ± 1.35 and 32.60 ± 1.80, respectively). Also, AI did not vary with breed, sex, or body size. CONCLUSIONS: The obtained radiographic and CT acetabular parameters could be useful as guidelines for evaluating the acetabulum of small-breed dogs in clinical practice.

Pilot study supporting the existence of novel lymphatic channels within the canine anterior uveal tract using Lyve-1 and CD31.

OBJECTIVE: To demonstrate the existence of lymphatics in the canine anterior uvea using lymphatic-specific markers Lyve-1, Prox-1, and podoplanin, the endothelial cell marker CD31, and basement membrane matrix marker collagen IV. DESIGN: Prospective Study. ANIMALS: Eight normal globes from animals euthanized for unrelated health problems. PROCEDURES: Sagittally cut serial sections of six normal canine eyes were immunofluorescence double-stained with Lyve-1 and CD31 and single-stained with colorimetric Prox-1 and collagen IV. Three serial sections from 2 additional eyes were cut in the coronal plane at the level of the ciliary body and immunofluorescence double-stained with Lyve-1 and CD31 to map lymphatic channel distribution. Lymphatics from normal canine lymph nodes were used for validation of podoplanin. RESULTS: Four of 6 of the sagitally sectioned eyes had Lyve-1-positive lymphatic-like structures that were distinct from CD31-positive blood vessels in the iris base and ciliary body. Both of the coronally sectioned globes had Lyve-1-positive lymphatic-like structures in the ciliary body. The location of these structures was evaluated and found to be diffusely present circumferentially around the ciliary body. CONCLUSION AND CLINICAL RELEVANCE: These results support the existence of lymphatic channels in the anterior uveal tract of the canine eye. This could indicate the presence of a novel uveolymphatic outflow pathway, which may play a role in aqueous humor outflow. Future studies are needed to confirm the existence and elucidate the role of this proposed uveolymphatic outflow pathway and potentially develop novel treatment options for managing glaucoma.

Canine induced pluripotent stem cell maintenance under feeder-free and chemically-defined conditions.

Canine induced pluripotent stem cells (ciPSCs) provide a platform for regenerative veterinary medicine, disease modeling, and drug discovery. However, in the conventional method, ciPSCs are maintained using chemically-undefined media containing unknown animal components under on-murine embryonic fibroblast feeder conditions, which were reported to modify cell surface of iPSCs and increases the risk of immune rejection when the cells are transplanted into patients. Moreover, in the conventional method, ciPSCs are mechanically passaged, which requires much time and effort. Therefore, the large-scale expansion of ciPSCs is difficult, which should be resolved for using ciPSCs in clinical application and research. Here, it was shown that StemFit® AK02N and iMatrix-511 could maintain the pluripotency of ciPSCs using conventional culture method. Furthermore, it was demonstrated that the feeder-free and chemically-defined ciPSC culture systems using StemFit® AK02N and iMatrix-511 could stably maintain and allow the easy expansion of ciPSCs generated using N2B27 and StemFit® AK02N, without causing karyotype abnormalities. ciPSCs expressed several pluripotency markers and formed teratomas, including cells derived from three germ layers.