A Morphometric Study on the Skull of the German Shepherd Dog (Alsatian)

In this study, a total of 33 skulls of German shepherd (Alsatian) puppies between 45 and 105 days old were used. Animals were divided into two groups. Group 1 included puppies between 45 and 60 days old, and group 2 included those between 61 and 105 days old. In group 1, a skull weight of 36.95 g, a skull length of 113.96 mm, a maximum zygomatic width of 66.52 mm, a cranial length of 71.31 mm, a maximum neurocranium width of 52.11 mm, a viscerocranial length of 50.28 mm, a skull index of 58.43, a cranial index of 73.24, a facial index of 133.13 and a cranial volume of 55.38 ml were measured. In group 2, a skull weight of 61.17 g, a skull length of 143.38 mm, a maximum zygomatic width of 73.54 mm, a cranial length of 83.38 mm, a maximum neurocranium width of 53.70 mm, a viscerocranial length of 68.64 mm, a skull index of 51.44, a cranial index of 64.57, a facial index of 107.96 and a cranial volume of 75.75 ml were obtained. In order to determine the likely relationship, if any, between the indices and the other parameters, correlation coefficients were computed. It was found that all the measurements increased with age, while indices decreased, and an insignificant positive correlation was found between cranial volume and skull weight. The data obtained in this study may be of use in the consideration of the German shepherd type. For German shepherd dogs, which are a dolichocephalic race, it should be agreed that, in line with growth, the farther the values are from the mean value, the higher the defect rate of a puppy is. Also, the data may be of use in investigating the correlation between, for example, nasal cancer risk and the shape of the skull.     

Post-natal development in the linear and tric morphometrics of the camelidae skull

The craniometric measurements in addition to the skull, cranial and facial indices undertaken in the immature and mature male Camelus dromedarius of the Malha phenotype (black) were: the skull length (35.99 cm), maximum width of neurocranium (11.33 cm), cranial length (15.45 cm), maximum zygomatic width (14.81 cm), viscerocranial length (20.55 cm), skull index (41.13), cranial index (73.70), facial index (72.31), cranial volume (231.73 ml) and skull weight (795.70 g) were measured in the immature camels. In the mature camels, the skulls gave the following measurements: the skull length (50.53 cm), maximum width of neurocranium (15.96 cm), cranial length (21.93 cm), maximum zygomatic width (22.75 cm), viscerocranial length (28.60 cm), skull index (45.06), cranial index (72.99), facial index (79.83), cranial volume (310.80 ml) and skull weight (2598.31 g). The results of a total of 30 skulls of immature and mature Malha camel revealed that all the measurements increased with age whereas the cranial index was the only parameter for which a decreased value was recorded. The anterior basicranial angle averaged about 203 degrees in the immature animal to increase to an insignificant value of 204 degrees in the mature camel skull. Similarly, the posterior basicranial angle did not exhibit a significant difference between the immature and mature values, which ranged between 110 and112 degrees,respectively.     

THE EFFECT OF OBLIQUITY ON THE RADIOGRAPHIC APPEARANCE OF THE TEMPOROMANDIBULAR JOINT IN DOGS

The temporomandibular joint is formed between the condyloid process of the mandible and the mandibular fossa of the temporal bone. The basic anatomy of this joint was assessed and described in a series of skulls including dolichocephalic, mesaticephalic and brachycephalic breeds. The facial index and rotational angles were measured with the facial index providing a useful method of classifying skull types but the rotational angle being of limited use in assessment of the temporomandibular joint until normal breed values are established. Equipment was designed to allow repeatable positioning of the temporomandibular joint for radiography at a variety of lateral and long axis rotational angles relative to the central x-ray beam. The regions of the joint and anatomic features visualized in each view are demonstrated. 10 degrees rotation was required in either axis to project the joints independently of each other. Lateral rotational angles of 10 to 30 degrees in mesaticephalic and dolichocephalic breeds and 20 to 30 degrees in brachycephalics and long axis rotational views of 10 to 30 degrees depending on the region of interest were considered to be the most useful.     

Canine nasal septum deviation can be a normal variation and correlates with increasing skull indices

Nasal septal deviation has been studied in relation to nasal pathology and mass effect in dogs. The purpose of this retrospective, cross‐sectional study was to compare the prevalence of nasal septal deviation in dogs with rhinitis, neoplasia, and those without nasal pathology based on the facial index, skull index, and cranial index. Computed tomographic studies of the nasal cavities of dogs performed over a 5‐year period were retrospectively reviewed. This study had 233 dogs meeting the inclusion criteria with 135 dogs with no nasal pathology, 63 dogs with nasal neoplasia, and 35 dogs with rhinitis. The prevalence of nasal septal deviation, the angle, maximum distance, and longitudinal extent of deviation were recorded, as well as measurements to calculate the facial index, cranial index, and skull index. The results showed no difference in the prevalence of nasal septal deviation between dogs with nasal pathology and those without. The mean longitudinal extent of deviation and maximum distance of deviation was statistically greater for those with neoplasia compared to those with rhinitis and without nasal pathology. The longitudinal extent of deviation was inversely proportional to the cranial index, facial index, and skull index. The angle of deviation was directly proportional to the facial index and skull index. In conclusion, nasal septal deviation is an anatomic variant in different breeds of dogs with no predilection based on nasal pathology. Nasal septal deviation should be interpreted cautiously in the assessment of canine nasal disease.     

Comparative morphometrical studies on the skull bones of barking deer (Muntiacus muntjak) and sambar deer (Rusa unicolor)

The present study reports data on the skull bone morphometry of barking and sambar deer. The skulls of adult barking deer (n = 6) and sambar deer (n = 6) of either sex (n = 3 males and n = 3 females) were collected from the Aizawl Zoological Park, Aizawl, Mizoram, India, with official permission from the Government of Mizoram. Anatomically, barking and sambar deer's skulls were elongated, pyramid-like, dolichocephalic and consisted of thirty-two cranial and facial bones. The cranial bones were eleven (three single and four paired), comprising of occipital, sphenoid, ethmoid, frontal, interparietal, parietal and temporal. The facial bones were twenty-one (one single and ten were paired), consisting of the maxilla, premaxilla (incisive), palatine, pterygoid, nasal, lacrimal, zygomatic (malar), vomer, turbinates, mandible and hyoid. In the present study, altogether 41 different measurements were taken morphologically and 6 different indices were applied. The obtained morphometrical parameters were significantly (p < .01, p < .05) higher in males than females of both species. Species wise, all obtained parameters were higher in sambar deer than barking deer. The obtained 41 different skull parameters and 6 indices showed statistically significant differences (p < .01 and p < .05) between both sexes of barking and sambar deer; however, practically these differences were meagre. The present morphometrical study on the skull of both species can help the wildlife professionals and zoo veterinarians determine the sex of these animals and differentiate it from other domestic and wild small ruminants for solving veterolegal cases. This study's findings will also motivate and assist other comparative studies with various domestic and wild small ruminants.     

Skull typology of byzantine dogs from the theodosius harbour at yenikapı, istanbul

This study presents the results of craniometric analysis of 500 Byzantine Era dog skulls from the ancient site of the Theodosius Harbour in Istanbul (modern Yenikap? neighbourhood). To determine the typology of the skulls, up to 36 craniometric measurements were taken on each specimen. Fourteen indices and ratios were calculated from the measurements. Results show that the majority (97%) of the Byzantine dogs from the Yenikap? excavations were of mesocephalic type. Only 15 of the analysed skulls (3%) were of the dolichocephalic type. Only one dog skeleton has been recovered in situ during the excavations; analysis indicates that this individual belonged to a mesocephalic type dog. Brachycephalic dog skulls were absent in the samples studied from Byzantine Yenikap?. The results give important insight in continuities and discontinuities in dog‐breeding traditions from the Roman to the Byzantine Eras, and between the West and the East during Medieval times.     

CEPHALOMETRIC MEASUREMENTS AND DETERMINATION OF GENERAL SKULL TYPE OF CAVALIER KING CHARLES SPANIELS

The general skull morphology of the head of the Cavalier King Charles Spaniel (CKCS) was examined and compared with cephalometric indices of brachycephalic, mesaticephalic, and dolichocephalic heads. Measurements were taken from computed tomography images. Defined landmarks for linear measurements of were identified using three‐dimensional (3D) models. The calculated parameters of the CKCS were different from all parameters of mesaticephalic dogs but were the same as parameters from brachycephalic dogs. However, the CKCS had a wider braincase in relation to length than in other brachycephalic breeds. Studies of the etiology of the chiari‐like malformation in the CKCS should therefore focus on brachycephalic control groups. As Chari‐like malformation has only been reported in brachycephalic breeds, its etiology could be associated with a higher grade of brachycephaly, meaning a shorter longitudinal extension of the skull. This has been suggested for other breeds.     

Comparative morphometric study of the mimic facial muscles of brachycephalic and dolichocephalic dogs

Excessive breeding of dogs has led to a disadvantageous morphology in some breeds, for example extreme brachycephaly, which is responsible for many health issues. We hypothesize that alterations of the mimic muscular system are present in brachycephalic dogs and could contribute to behavioural problems due to a restricted mimic display. Therefore, the purpose of this paper was to compare the mimic muscular systems of brachycephalic with dolichocephalic dogs. Mimic muscles were measured and set in ratio to measurements of the head and calculated indices. When bringing the length of the muscles m(x) in proportion to the length of the head, highly significant differences (p < .0001) and significant difference (p < .05) were found in all but two of the examined muscles. Calculations of the m(x) divided by the cranial index and the square index showed significant differences for all muscles. For example, the musculus (m.) levator nasolabialis was morphologically different from the one of dolichocephalic dogs. Muscle fibres of the m. levator nasolabialis were localized in the fold over the nasal bridge of brachycephalic dogs. The raphe of the m. orbicularis oris was not always apparent in brachycephalic dogs. The proportions of the muscle lengths and the length of the eye slots to the size of the skull have shifted considerably in brachycephalic dogs. We conclude that many alterations contribute to the strong shift in the proportions of the head of brachycephalic dogs versus that of dolichocephalic dogs. Our findings suggest that brachycephalic dogs have reduced mimic skills that can lead to ambiguous communication.     

Conformation of the equine skull: a morphometric study

There is a lack of an established method for quantifying equine skull morphology. This study proposes a method that is valid for use on both live and deceased horses. A total of nine head measurements (skull length, cranial length, nasal length, ratio of cranial:nasal length, cranial width, zygomatic width, mandibular depth, nasal profile area, cranial profile area) and six indices (skull index, cranial index, nasal index, mandibular index, nasal profile index, cranial profile index) were recorded from 30 horses from a variety of breeds whilst the soft tissues of the head were intact. A line was drawn level with the palpable notches caudal to the caudal lacrimal process of each orbit to estimate the suture line of the nasal and frontal bones and distinguish between the neurocranium and splanchnocranium. There were positive correlations between many of the head measurements. This method also illustrated significant differences in the skull morphology of three breeds (Arabians, thoroughbreds and standardbreds).     

Morphometric analysis of the skull of Hamdani sheep via Three-Dimensional modelling

The aim of the present study was to determine the craniometric characteristics of the crania of Hamdani sheep, one of local breeds of Turkey, by using computed tomography (CT). In the study, 13 (six female and seven male) skulls were used. After CT images of the skulls were taken, their three-dimensional models were created by MIMICS 20.1 (The Materialise Group, Leuven, Belgium) program. Thirty-eight craniometric measurements were taken over the models created and nine indices were calculated by using these measurements. All the characteristics examined were expressed as mean ± SE. In the study, statistically significant differences were found between females and males in terms of greatest neurocranium breadth, facial breadth, greatest palatal breadth (p < 0.05) and height of the foramen magnum (p < 0.01) parameters. No statistically significant difference was observed between the sexes in the calculated index values (p > 0.05). In conclusion, it is thought that the findings obtained from the study will contribute to the zooarchaeology and sheep taxonomy of Mesopotamian region.     

Domestic dog skull diversity across breeds,breed groupings,and genetic clusters

Domestic dogs have become a model organism for studying the extent and consequences of morphological diversity, especially in the skull. It has been demonstrated that Cephalic Index (CI, skull width/skull length) correlates with central concentration of ganglion cells in the retina and with ventral rotation of the cerebral hemispheres. These changes may be reflected in the behavior of breeds with different skulls shapes. This study explored skull variation in the breed groups (n = 7) described by the Australian National Kennel Club to determine if CI differed significantly among the breed groups; groups were expected to differ not least in behavior. The CI of 12 representative dogs (females, n = 6; males, n = 6) of the most popular breeds (n = 80; total n = 960 dogs) were measured. Multivariate analysis of variance was performed to determine CI variance among the breed groups and between previously reported clusters of breeds with similar DNA, which identifies common ancestry. Although CI differed significantly among some breed groups, neither the breed groupings nor the DNA clusters satisfactorily explained all the variance in CI. The results show that breed groupings and genetic clusters only partially explain CI differences. They also suggest that CI is on a continuum and that the definition of three categories of canine skull as dolichocephalic, mesocephalic, and brachycephalic may be overly arbitrary.     

High-resolution computed tomography bronchial lumen to pulmonary artery diameter ratio in anesthetized ventilated cats with normal lungs

High-resolution computed tomography (CT) is the preferred noninvasive tool for diagnosing bronchiectasis in people. A criterion for evaluating dilation of the bronchus is the bronchial lumen to pulmonary artery diameter (bronchoarterial ratio [BA ratio]). A ratio of > 1.0 in humans or > 2.0 in dogs has been suggested as a threshold for identifying bronchiectasis. The purpose of this study was to establish the BA ratio in normal cats. Fourteen specific pathogen-free cats were selected for analysis of thoracic CT images. The BA ratios of the lobar bronchi of the left cranial (cranial and caudal parts), right cranial, right middle, left caudal, and right caudal lung lobes were measured. The mean of the mean BA ratio of all lung lobes was 0.71 +/- 0.05. Individual BA ratios ranged from 0.5 to 1.11. Comparing individual lobes for each cat, there was no significant difference (P = 0.145) in mean BA ratio between lung lobes. A mean BA ratio for these normal cats was 0.71 +/- 0.1, which suggests an upper cut-off normal value > 0.91 (mean +/- 2 standard deviations) between normal and abnormal cats.     

A computed tomography–based method for the assessment of canine retrobulbar cone volume for ophthalmic anaesthesia

ObjectiveTo develop a comprehensive formula for calculating the volume of local anaesthetic solution used for retrobulbar anaesthesia in dogs with different skull morphologies.Study designRetrospective cohort imaging study.AnimalsSkull computed tomography (CT) images of 188 dogs of different breeds collected between January 2009 and December 2017.MethodsAnatomical integrity of the orbit and adjacent structures, presenting complaint, clinical signs and CT findings were verified to exclude ocular abnormalities. The volume of the retrobulbar cone of 376 eyes was calculated using CT scans of the dogs’ skulls. Additional data recorded included morphology of the skull, body weight, sex and size of the dogs, all of which were matched for possible association to the retrobulbar cone volume through univariable and multivariable linear regression models. Results of linear regression models were expressed as estimated beta coefficients with the corresponding 95% confidence intervals (95% CIs).ResultsUsing univariate analysis, the retrobulbar cone volume was positively associated with weight and male sex. In addition, brachycephalic and dolichocephalic dogs showed a larger retrobulbar cone volume than mesocephalic dogs, while sex was no longer significantly associated with the retrobulbar cone volume. In multivariate analysis, when considering all variables in the model, weight emerged as the strongest predictor (beta coefficient: 0.062 mL kg^–1, 95% CI: 0.056–0.067 mL kg^–1, p < 0.001).Conclusionsand clinical relevance In the veterinary literature, there is no agreement on the precise volume of local anaesthetic solution that should be used to achieve intraconal retrobulbar anaesthesia in dogs. Here we suggest a formula to calculate the retrobulbar cone volume and, accordingly, the injection volume of local anaesthetic solution for effective retrobulbar anaesthesia.     

Intraobserver and interobserver agreement, reproducibility, and accuracy of computed tomographic measurements of pituitary gland dimensions in healthy dogs

OBJECTIVE: To determine the reproducibility and accuracy of computed tomographic (CT) measurements of pituitary gland dimensions in healthy dogs. ANIMALS: 35 healthy sexually intact adult dogs. PROCEDURES: 2 observers independently viewed CT images of the skull in 35 dogs twice. Pituitary gland height, width, length, and volume and pituitary gland height-to-brain area ratio (P:B ratio) were measured or calculated. Intraobserver and interobserver agreement indexes (AIs) were calculated for pituitary gland dimensions. Computed tomography was performed also on 5 phantoms, and both observers measured phantom dimensions twice. True-value AIs were calculated for the phantom study. RESULTS: The mean +/- SD interobserver AI between observer 1 and 2 for pituitary gland height and the P:B ratio was 0.90 +/- 0.07. The intraobserver AI for pituitary gland height and the P:B ratio was 0.97 +/- 0.04 for observer 1 and 0.94 +/- 0.04 for observer 2. The intra and interobserver AIs for the other dimensions were lower than those for pituitary gland height and the P:B ratio. All phantom dimensions on CT images were underestimated significantly, compared with their true values. CONCLUSIONS AND CLINICAL RELEVANCE: The intra- and interobserver AIs for pituitary gland dimension measurements on CT images were high. However, the same observer preferably should perform serial measurements. Window settings influence pituitary gland dimension measurements, and predetermined window settings are recommended to make comparisons among dogs. Pituitary gland dimension measurements made from CT images in our study underestimated the true values.     

An anatomical study of the dorsal and ventral nasal conchal bullae and middle nasal conchae in normal Shetland ponies: Computed tomographic anatomical and morphometric findings

Equine paranasal sinuses are susceptible to inflammation. Insufficient drainage through the nasal passages and meatus may lead to the accumulation of inspissated purulent discharge. Particularly in ponies, these anatomical structures are suspected to be relatively small. To date, there are no reports considering the morphology of nasal conchal bullae in small horse breeds such as Shetland ponies. The aim of the present study was to evaluate the size of the conchal bullae and the medial nasal conchae of Shetland ponies and their relation to the skull dimension using computed tomography. Reconstructed images of healthy adult heads of Shetland ponies were used. Linear skull measurements as well as two cranial indices of the head dimensions were taken. Length, width and height of the dorsal and ventral conchal bullae and the medial nasal conchae were measured in relation to the skull and compared with the data of skulls of large breed horses. The anatomical proportions of pony heads were characterized by a smaller cranial index and a greater nasal index than those of large breed horses. Shetland ponies showed a longer cranial length compared with the nasal length. Heads are consistently smaller, and the relationship of the bullae to the head length was also smaller than those measured in large breed horses. A negative correlation between the head and bullae size was found. In conclusion, this study suggests that Shetland ponies have distinguishing proportions of the head. These findings are relevant for clinical examination and surgical treatment of equine sinus disease in those breeds.     

The prevalence of dynamic pharyngeal collapse is high in brachycephalic dogs undergoing videofluoroscopy

The aim of this retrospective study was to determine the frequency of pharyngeal collapse in a large group of brachycephalic dogs undergoing videofluoroscopic assessment of swallowing or airway diameter. We hypothesized that brachycephalic dogs would have pharyngeal collapse more frequently than dolichocephalic or mesocephalic dogs with or without airway collapse. The medical records database was searched for brachycephalic dogs undergoing videofluoroscopy of swallowing or airway diameter between January 1, 2006 and December 31, 2015. A cohort of dolichocephalic/mesocephalic dogs with videofluoroscopically confirmed airway collapse was age and time matched for comparison. A control group of dolichocephalic/mesocephalic dogs that did not have documented airway collapse was also evaluated. All fluoroscopic studies were assessed by a board certified veterinary radiologist for the presence and degree of pharyngeal collapse. Results demonstrate that pharyngeal collapse was significantly more common in brachycephalic dogs (58/82; 72%) than in nonbrachycephalic dogs with (7/25; 28%) and without (2/30; 7%) airway collapse. Pharyngeal collapse is more prevalent in brachycephalic dogs undergoing videofluoroscopy than in dolichocephalic/mesocephalic dogs with or without airway collapse.     

Plasma amino acid analysis in dogs with experimentally induced hepatocellular and obstructive jaundice

Plasma amino acid concentrations were determined weekly for 4 weeks in 6 sham-operated control dogs, in 6 sham-operated dogs after induction of liver disease with dimethylnitrosamine (DMNA), and in 6 dogs after surgical ligation of the common bile duct. Results were compared with standard biochemical indices of liver function and with histologic changes in serial liver biopsy specimens. Concentrations of most amino acids increased after 2 weeks in DMNA-treated dogs, whereas they were normal or decreased in bile duct-ligated dogs. With increasing severity of the liver disease, the molar ratio (normal mean +/- SEM = 3.48 +/- 0.14) in DMNA-treated dogs decreased to 2.42 +/- 0.19 by 2 weeks and to 1.17 +/- 0.09 by 4 weeks. The ratio remained normal in bile duct-ligated dogs. Molar ratio and aromatic amino acid concentrations correlated better with hepatic necrosis and inflammation than did standard biochemical indices (eg, bilirubin, liver enzymes). Therefore, plasma amino acid analysis and determination of the molar ratio may be useful in the differential diagnosis of hepatocellular and obstructive jaundice in dogs. A decrease in the molar ratio may reflect portal hypertension and hepatocellular disease.     

A study on morphology and morphometric parameters on skull of the Bardhoka autochthonous sheep breed in Kosovo

In this study, we aim to investigate the skull of Bardhoka sheep, which is the native breed of Kosovo by utilising normal morphometric methods. Differences between male and female were also statistically analysed. Further, the parameters that can be used in gender discrimination were also analysed. The statistical analysis was based on a sample of 24 adult skulls of Bardhoka breed with 12 female and 12 male skulls. Altogether, 31 different measurements were taken morphologically and 7 different indices were applied. Except for the measurement's values of the orbit, measurement's values of length of the cheek tooth row and the measurement's values of height of the foramen magnum, all the measured values of males were higher than females. Nasal index, cranium index and skull index values were statistically significant between both genders. It is envisaged that the findings of this study will motivate and assist other comparative studies with other autochthonous sheep and goat breeds found in the Dukagjini region or in clinical veterinary practice and even in zooarchaeology.     

M-mode echocardiographic ratio indices in normal dogs, cats, and horses: a novel quantitative method

A novel method for quantitative echocardiographic interpretations is introduced based on the calculation of ratio indices in which each raw M-mode measurement is divided by the aortic root dimension (Ao). "Aorta-based" indices were calculated with the animal's measured aortic root dimension (Ao(m)) as the length standard. Conversely, "weight-based" indices employed an idealized estimate of aortic dimension (Ao(w)) with a weighted least squares linear regression against the cube root of body weight (Ao(w) = kW(1/3)). Use of these indices circumvented undesirable statistical characteristics inherent in linear regression of echocardiographic dimensions against body weight and, to a lesser extent, body surface area. Compared with the regressions, ratio indices resulted in substantial refinement of the predictive range for each M-mode measurement in dogs, particularly with decreasing body size. Weight-based indices outperformed aorta-based indices in this regard. To refine the predictive range, neither type of index was clearly advantageous in cats compared with the simple average method typically employed for that species. Several of the raw M-mode measurements, however, were correlated with body weight in cats and horses, indicating the need for an appropriate correction for body size in these species. The ratio index method was suitable for this purpose. Summary statistics derived from normal dogs (n = 53), cats (n = 32), and horses (n = 17) are presented for each index, including novel clinical indices calculated from area ratios. The latter were designed to represent body size-adjusted lett ventricular stroke area (ie, volume overload) and myocardial wall area (ie, hypertrophy).     

Pharmacokinetics of topically applied ciprofloxacin in tears of mesocephalic and brachycephalic dogs

OBJECTIVE: To evaluate the pharmacokinetics of ophthalmic ciprofloxacin in the tear film of normal mesocephalic and brachycephalic dogs. ANIMALS STUDIED: Twenty mesocephalic dogs and 15 brachycephalic dogs. PROCEDURES: Thirty-five microliters of ciprofloxacin were placed on the cornea of both eyes of each dog. Five brachycephalic dogs were used twice. A tear-test strip placed in the ventral cul de sac for 30 s was used to obtain samples. The tear film of each eye was sampled once at eight time-points post administration, resulting in five samples at each time-point. Samples were evaluated using high performance liquid chromatography. Data from the two skull types were compared using the unpaired two-tailed t-test. RESULTS: The mean concentration of ciprofloxacin in the tears of mesocephalic dogs was 192.8 +/- 269.97, 140.6 +/- 91.06, 56.60 +/- 28.47, 13.6 +/- 6.3, 43.25 +/- 59.71, 16.6 +/- 10.62, 15.6 +/- 13.16 and 6.25 +/- 9.84 microg/g at 5, 10, 15, 30 min and 1, 2, 4 and 6 h, respectively. The mean concentration of ciprofloxacin in the tears of brachycephalic dogs was 272.6 +/- 106.21, 144.4 +/- 142.32, 131.2 +/- 147.07, 75 +/- 80.07, 40.8 +/- 30.35, 35 +/- 21.98, 52.75 +/- 51.87 and 8.6 +/- 12.10 microg/g at 5, 10, 15, 30 min and 1, 2, 4 and 6 h, respectively. There was no statistical difference in tear concentration at any time-point between skull types. CONCLUSIONS: Topical application of ciprofloxacin resulted in a mean tear concentration of ciprofloxacin that remained above the MIC(90) levels for most pathogenic bacteria for 6 h in normal mesocephalic and brachycephalic dogs.