[Brain abcesses associated with a systemic infection by Nocardia Farcinica]. / Abcès cérébraux a Nocardia Farcinica dans le cadre d'une infection systémique.

The prevalence of nocardia infections is increasing because of both improved detection laboratory techniques and a higher number of immunosuppressed patients. We report the case of a patient with brain abcesses resulting from nocardia farcinica cerebral dissemination associated with lung infection, endocarditis and ocular lesions for which we suspected a similar origin. This case gives the opportunity to discuss the main issues of these infections and the current therapeutic guidelines.

La prévalence des infections à nocardia est en augmentation depuis plusieurs années en raison, d'une part, de l'amélioration des techniques de détection de ces germes en laboratoire et, d'autre part, d'un nombre accru de patients immunodéprimés. Nous rapportons ici l'histoire d'un patient porteur d'une infection multifocale à Nocardia Farcinica associant des abcès cérébraux, une infection pulmonaire, une endocardite et une atteinte ophtalmique. Ce cas permet de discuter les principales caractéristiques de ces infections, ainsi que les recommandations thérapeutiques actuelles.

Ancestral haplotype-based association mapping with generalized linear mixed models accounting for stratification.

MOTIVATION: In many situations, genome-wide association studies are performed in populations presenting stratification. Mixed models including a kinship matrix accounting for genetic relatedness among individuals have been shown to correct for population and/or family structure. Here we extend this methodology to generalized linear mixed models which properly model data under various distributions. In addition we perform association with ancestral haplotypes inferred using a hidden Markov model. RESULTS: The method was shown to properly account for stratification under various simulated scenari presenting population and/or family structure. Use of ancestral haplotypes resulted in higher power than SNPs on simulated datasets. Application to real data demonstrates the usefulness of the developed model. Full analysis of a dataset with 4600 individuals and 500 000 SNPs was performed in 2 h 36 min and required 2.28 Gb of RAM. AVAILABILITY: The software GLASCOW can be freely downloaded from www.giga.ulg.ac.be/jcms/prod_381171/software. CONTACT: francois.guillaume@jouy.inra.fr SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Biochemical markers of bone turnover during pregnancy in horses: a longitudinal study.

The effect of pregnancy on bone metabolism was investigated in healthy mares. Venous blood samples were collected 7 times from 19 multiparous mares starting at 20-weeks pre-parturition, continuing 6 times in 4-week intervals, including the week of parturition and one week after parturition. Serum concentrations of osteocalcin (OC) and carboxy-terminal cross-linking telopeptide of type I collagen (CTX-I) were determined. Measurement cycles and age had a significant (p < 0.01) influence on OC and CTX-I values. Pregnancy influenced bone metabolism with peak bone formation and resorption values around the time of parturition.

Caudal vena cava point-of-care ultrasound in dogs with degenerative mitral valve disease without clinically important right heart disease.

OBJECTIVES: Caudal vena cava (CVC) diameter and collapsibility index (CVCD and CVCCI) have been used to assess intravascular volume status (IVS). Maladaptations with progressive degenerative mitral valve disease (DMVD) lead to hypervolemia. We hypothesised that stages of DMVD will affect ultrasonographic CVC variables in dogs without clinically important right heart disease. ANIMALS, MATERIALS AND METHODS: This retrospective study included 79 dogs with DMVD presented to the cardiology department between January 2017 and 2019. Subxiphoid views were used to obtain CVC cineloops. By visual inspection, CVC was subjectively scored as flat, normal or fat. Maximal and minimal CVCD were measured and indexed to aortic diameter (CVCD-max/Ao and CVCD-min/Ao); CVCCI was calculated as (CVCD-max-CVCD-min)/CVCD-max. Fisher's exact and Kruskal-Wallis tests were used to compare CVC variables. RESULTS: Subjective assessment was associated with American College of Veterinary Internal Medicine (ACVIM) stages (P < 0.001). The proportion of fat CVC was greater in stages C and D. In stage D, CVCD-max/Ao was larger compared with stages B1, B2 and C (P = 0.002, P = 0.002 and P = 0.035, respectively). In stages C and D, CVCD-min/Ao was larger compared with B1 (P = 0.016 and P = 0.001) and B2 (P = 0.002 and P < 0.001. In stages C and D, CVCCI was less than stage B1 (P = 0.016 and P = 0.044) and B2 (P = 0.001 and P = 0.010). CONCLUSIONS: In dogs with DMVD without clinically important right heart disease, CVC variables differ across ACVIM stage. Subjective and objective CVC variables may be used to predict hypervolemia.

Duration of corneal anaesthesia following multiple doses and two concentrations of tetracaine hydrochloride eyedrops on the normal equine cornea.

REASONS FOR PERFORMING STUDY: There is a clinical impression that tetracaine hydrochloride (THCl) eyedrops is a suitable topical anaesthetic in horses. OBJECTIVE: To determine the duration of corneal anaesthesia following instillation of multiple doses and 2 concentrations of THCl in 10 healthy horses. METHODS: The corneal touch threshold (CTT) was determined, in both eyes, before (basal CTT) and after application of one drop of 0.5% THCl, 2 drops at a 1 min interval of 0.5% THCl or one drop of 1% THCl. CTT was measured in mm every 5 min until complete recovery of the basal CTT. Treatments were separated by an interval of at least one week. RESULTS: Corneal sensitivity was significantly reduced from baseline values for 30, 60 and 50 min after application of one drop of 0.5% THCl, 2 drops of 0.5% THCl and one drop of 1% THCl, respectively. Mean maximal anaesthetic effects, corresponding to a CTT of 0 mm, lasted 5.5, 16 and 15.25 min and maximal anaesthetic effect was present in 55, 90 and 80% of eyes, 5 min after application of one drop of 0.5% THCl, 2 drops of 0.5% THCl and one drop of 1% THCl, respectively. CONCLUSIONS: The application of a second drop or the use of more concentrated eyedrops significantly increases duration of both anaesthesia and maximal anaesthetic effect. POTENTIAL RELEVANCE: Duration of corneal anaesthesia following tetracaine instillation was established enabling a better use when performing diagnostic and therapeutic procedures. Comparison of tetracaine with other ocular anaesthetics needs to be published in the future.

Determination of tear break-up time reference values and ocular tolerance of tetracaine hydrochloride eyedops in healthy horses.

REASONS FOR PERFORMING STUDY: Tetracaine hydrochloride (THCl) has been reported to cause irritation in dogs. In man, some topical anaesthetics have been shown to disrupt the tear film. Tear break-up time (TBUT) is a useful test allowing an assessment of the quality of the precorneal tear film. Only one TBUT value has been reported in horses with no information on the technique used. OBJECTIVES: To provide a method for performing the TBUT in horses and to report any side effects of a single application of THCl in clinically normal horses, particularly on the stability of the tear film. METHODS: In Study 1, one drop of 0.5 or 1% THCl was applied to one eye of 20 horses divided in 2 groups. Treated eyes were assessed for the development of side effects 2.5 and 5 min after treatment. In Study 2, the TBUT was measured in both eyes of 2 groups of 10 horses, before and 2.5 and 5 min after, instillation of one drop of either 0.5 or 1% THCl. RESULTS: No animals developed any ocular side effect after instillation. Basal TBUT was 8.3±1.3 s. TBUT decreased from baseline 5 and 2.5 min after application of one drop of 0.5% THCl and one drop of 1% THCl, respectively. CONCLUSIONS: A technique to measure the TBUT in healthy horses is described and normal range values that could be used as a reference were obtained. POTENTIAL RELEVANCE: THCl is well tolerated in horses but lowers the TBUT.

Bovine herpesvirus 4 ORF73 is dispensable for virus growth in vitro, but is essential for virus persistence in vivo.

ORF73 orthologues encoded by different rhadinoviruses have been studied extensively. These studies revealed that the ORF73 expression product (pORF73) is a multifunctional protein essential for latency that enables episome tethering to mitotic chromosomes and modulates cellular pathways implicated in growth and survival of latently infected cells. Comparison of pORF73 orthologues encoded by rhadinoviruses reveals important variations in amino acid sequence length and composition. Bovine herpesvirus 4 (BoHV-4) encodes by far the shortest ORF73 orthologue, with a size equivalent to only 22 % of that of the largest orthologues. The present study focused on determining whether BoHV-4 ORF73 is a bona fide gene and investigating whether it is essential for latency, as established for larger ORF73 orthologues. Our results demonstrate that BoHV-4 ORF73 is transcribed as immediate-early polycistronic mRNA together with ORF71. Using a BoHV-4 bacterial artificial chromosome clone, we produced a strain deleted for ORF73 and a revertant strain. Deletion of BoHV-4 ORF73 did not affect the capacity of the virus to replicate in vitro, but it prevented latent infection in vivo using a rabbit model. Interestingly, the strain deleted for ORF73 induced an anti-BoHV-4 humoral immune response comparable to that elicited by the wild type and revertant recombinants. Together, these results demonstrate that, despite its relatively small size, BoHV-4 ORF73 is a functional homologue of larger rhadinovirus ORF73 orthologues, and highlight the potential of ORF73 deletion for the development of BoHV-4 as a vector in vaccinology.

Polar overdominance at the ovine callipyge locus.

An inheritable muscular hypertrophy was recently described in sheep and shown to be determined by the callipyge gene mapped to ovine chromosome 18. Here, the callipyge phenotype was found to be characterized by a nonmendelian inheritance pattern, referred to as polar overdominance, where only heterozygous individuals having inherited the callipyge mutation from their sire express the phenotype. The possible role of parental imprinting in the determinism of polar overdominance is envisaged.

Assessing interventions by quantitative risk assessment tools to reduce the risk of human salmonellosis from fresh minced pork meat in Belgium.

The risk of human salmonellosis through the consumption of minced pork meat in Belgium was assessed via a modular risk model covering pork meat production from lairage to human consumption. The main goal of the model was to give concrete options to reduce effectively the risk of human salmonellosis through the consumption of minced pork meat. These options (scenarios) were elaborated with reference to the international situation and the literature to give concrete and realistic possibilities for improving the microbiological quality of pork meat and to reduce the number of human salmonellosis cases per year in Belgium. The model estimates 15,376 cases of human salmonellosis per year in Belgium due to the consumption of minced pork meat. The results of the scenarios showed that the risk of human salmonellosis could be significantly reduced by efforts all along the pork meat production chain but also by efforts made by consumers. The responsibility of food business operators for the pork meat production chain is high in relation to the microbiological quality of meat delivery, especially at the slaughterhouse. Consumers also need to be aware of good hygiene practices during preparation of the meat at home. Cross-contamination with raw food can be avoided by changing the habits and the behavior of the household cook. The results of these scenarios would be useful for the food business operators involved in the pork meat chain and for public health authorities.

Salmonella surveillance and control at post-harvest in the Belgian pork meat chain.

Salmonella remains the primary cause of reported bacterial food borne disease outbreaks in Belgium. Pork and pork products are recognized as one of the major sources of human salmonellosis. In contrast with the primary production and slaughterhouse phases of the pork meat production chain, only a few studies have focussed on the post-harvest stages. The goal of this study was to evaluate Salmonella and Escherichia coli contamination at the Belgian post-harvest stages. E. coli counts were estimated in order to evaluate the levels of faecal contamination. The results of bacteriological analysis from seven cutting plants, four meat-mincing plants and the four largest Belgian retailers were collected from official and self-monitoring controls. The prevalence of Salmonella in the cutting plants and meat-mincing plants ranged from 0% to 50%. The most frequently isolated serotype was Salmonella typhimurium. The prevalence in minced meat at retail level ranged from 0.3% to 4.3%. The levels of Salmonella contamination estimated from semi-quantitative analysis of data relating to carcasses, cuts of meat and minced meat were equal to -3.40+/-2.04 log CFU/cm(2), -2.64+/-1.76 log CFU/g and -2.35+/-1.09 log CFU/g, respectively. The E. coli results in meat cuts and minced meat ranged from 0.21+/-0.50 to 1.23+/-0.89 log CFU/g and from 1.33+/-0.58 to 2.78+/-0.43 log CFU/g, respectively. The results showed that faecal contamination still needs to be reduced, especially in specific individual plants.

CSF omeprazole concentration and albumin quotient following high dose intravenous omeprazole in dogs.

Clinical signs of syringomyelia and hydrocephalus occur secondary to cerebrospinal fluid (CSF) accumulation within the central nervous system. Omeprazole is recommended to treat these conditions despite little evidence of its capacity to decrease CSF production in the dog. Studies into new treatments are hampered by difficulties in measuring CSF production. The albumin quotient (QAlb), the ratio between CSF and serum albumin concentrations, may reflect CSF production and any decrease in CSF production should be associated with an increase in QAlb. The primary objective of this study was to determine CSF omeprazole concentration after administration of a high intravenous dose of omeprazole and to evaluate its impact on QAlb in the dog. The second aim was to validate QAlb as a surrogate marker of CSF production. Eighteen dogs were included in this prospective crossover placebo-controlled study. Each dog received omeprazole (10 mg/kg), acetazolamide (50 mg/kg) combined with furosemide (1 mg/kg) and saline. Blood and CSF samples were obtained on day 0 and then every 7 days, one hour after drug administration. Omeprazole concentrations (2.0 ±â€¯0.4 µmol/L) reached in CSF after high dose omeprazole were lower than the concentrations previously described as decreasing CSF production in dogs. There was no significant increase in QAlb following administration of acetazolamide/furosemide, prohibiting validation of QAlb as a surrogate marker for CSF production. Several dogs presented transient mild side effects after injection of acetazolamide/furosemide. High dose omeprazole was well tolerated in all dogs.

Risk factors for Salmonella and hygiene indicators in the 10 largest Belgian pig slaughterhouses.

A survey was conducted to collect data on Salmonella prevalence, Escherichia coli counts (ECCs), and aerobic bacteria colony counts (ACCs) on pig carcasses after chilling at the 10 largest Belgian pig slaughterhouses during 2000 through 2004. Potential risk factors of contamination associated with production parameters, technical descriptions of the installations, and cleaning and disinfection methods were assessed during investigations in the slaughterhouses. These variables were used first in a univariate analysis and then were extended to a multivariate analysis with a logistic mixed regression model for Salmonella and a linear mixed model for ECCs and ACCs with slaughterhouses as the random effect. The results indicated high variability concerning Salmonella contamination among the 10 slaughterhouses, with prevalence ranging from 2.6 to 34.3% according to the area of origin. The median ECC and median ACC ranged from -0.43 to 1.11 log CFU/cm2 and from 2.37 to 3.65 log CFU/cm2, respectively. The results of the logistic and linear regressions revealed that some working practices such as scalding with steam, second flaming after polishing, and complete cleaning and disinfection of the splitting machine several times a day were beneficial for reducing Salmonella prevalence, ECCs, and ACCs. Changing the carcass hooks just before chilling, using water as the cleaning method, and a higher frequency of disinfection of the lairage seemed to be protective against E. coli in the multivariate mixed linear model. The monitoring of critical points, slaughterhouse equipment, good slaughtering practices, and effective washing and disinfection are the keys to obtaining good microbiological results.

Pathogenicity and thermotolerance of entomopathogenic fungi for the control of the scab mite, Psoroptes ovis.

Psoroptes ovis is responsible for a highly contagious skin condition, both in sheep and cattle. This parasite has a marked economical impact in the sheep and cattle industry. Biological control is considered as a realistic alternative to chemotherapeutic control. Laboratory experiments were carried out to evaluate the pathogenicity and the thermotolerance of twelve isolates of entomopathogenic fungi from four genera (Beauveria Vuillemin, Metarhizium Sorokin, Paecilomyces Bainier and Verticillium Nees). The pathogenicity was evaluated by the survival of P. ovis females after exposure to 10(6) to 10(8) conidia ml(-1) in humidity chambers. Results revealed intra- and interspecies differences. All isolates with the exception of B. bassiana IHEM3558 and V. lecanii MUCL8672 induced 50% mortality within 2 days at the highest concentration. At this concentration the entire mite population became infected with all isolates but B. bassiana IHEM3558; however, only four isolates gave rise to 100% infected cadavers at the lowest concentration. The thermotolerance of each isolate was evaluated by measuring its growth on an artificial medium kept between 25 and 37.5 degrees C. All isolates were able to grow up to 30 degrees C but only two, M. anisopliae IHEM18027 and Paecilomyces farinosus MUCL18885, tolerated temperatures up to 35 degrees C. These two isolates could be considered as good candidates for further use as biopesticide taking into account their virulence and thermotolerance. Other critical factors linked with the implementation of this type of biocontrol in P. ovis infected animals are discussed.

Effects of a P-class CpG-ODN administered by intramuscular injection on plasma cytokines and on white blood cells of healthy horses.

Cytosine-phosphate-guanosine (CpG-ODN) has been described as a potent immunostimulatory agent in different species. No study reported the effect of a P-class CpG when administered systemically in healthy horses. The aim of this study was to evaluate the tolerance and the effect of an intramuscularly administered P-class CpG-ODN on hematology and on plasma cytokines (IFN-α, IL-10, TNF-α, IFN-γ) in 8 healthy horses. Intra-muscular CpG-ODN or placebo (PBS) was administered twice at a 7 days-interval. Groups were inversed after 2 months of washout period. A physical examination, complete blood count (CBC) and plasma cytokine measurements were performed from 2 days before injection up to 21 days after injection. P-class CpG-ODN injection was well tolerated with minor side effects. After the first injection a significant transient drop in circulating total leukocytes, lymphocytes and an increase in monocytes were observed. A transient drop in eosinophils was also noted after each CpG injection. P-class CpG-ODN at a dose of 5 mg did not create major side effects in 7 horses, one horse showed transient pyrexia. A redistribution of white blood cells was observed in horses receiving CpG, but no change in plasma cytokines was observed at the indicated dose, route of administration and sampling times.

Reference values of two-dimensional and M-mode echocardiographic measurements as a function of body size in various equine breeds and in ponies.

INTRODUCTION: The aim of this study was to establish echocardiographic reference values for the equine species using allometric regression equations based on body weight (BW) and thoracic circumference (TC). ANIMALS: A total of 239 horses or ponies were studied, including 65 warmbloods, 33 Standardbreds, 41 Thoroughbreds, 32 Arabian horses, 28 draft horses, and 40 ponies aged from 1 day to 30 years, weighing from 18 to 890 kg, with no evidence of cardiac disease. METHODS: For each horse or pony, a two-dimensional and M-mode echocardiography was performed. Within each breed, the relationships between BW or TC and echocardiographic dimensions were examined using power regression equations. Predictions and their 95% prediction intervals were calculated for the echocardiographic measurements. RESULTS: Within each breed, all echocardiographic measurements showed a significant and positive relationship with a high coefficient of determination for the estimation of the regression equations using BW and TC as the main explanatory variables. Breed-specific power regression equations as well as the 95% prediction intervals were calculated for each echocardiographic measurement as a function of BW and TC. CONCLUSIONS: In the future, the body size-corrected and breed-specific echocardiographic reference values calculated in the present study could be used to discriminate between normal and abnormal values in a given animal.

Axillary temperature measurement: a less stressful alternative for hospitalised cats?

Rectal temperature measurement (RTM) can promote stress and defensive behaviour in hospitalised cats. The aim of this study was to assess if axillary temperature measurement (ATM) could be a reliable and less stressful alternative for these animals. In this prospective study, paired rectal and axillary temperatures were measured in 42 cats, either by a veterinarian or a student. To assess the impact of these procedures on the cat's stress state, their heart rate was checked and a cat stress score (CSS) was defined and graded from 1 (relaxed) to 5 (terrified). A moderate correlation was found between RTM and ATM (r=0.52; P<0.0001). RTM was on average 0.9 °C (1.6 °F) higher than ATM (P<0.0001), although a wide variation was found in the difference between these two measurements (-2.1 °C to 3.6 °C (-3.8 °F to 6.5 °F)). ATM failed to identify hypothermia in 25 per cent of the cases and hyperthermia in 19 per cent of the cases but may be considered less stressful than RTM. Indeed, RTM induced a mildly greater increase in heart rate (+6 bpm; P=0.01) and in CSS (+0.2; P=0.001) than ATM. The results were not affected by operator type. In conclusion, RTM should remain the standard method to obtain accurate temperatures in cats.

Effects of character weighting and species sampling on phylogeny reconstruction: a case study based on DNA sequence data in cetaceans.

Different phylogenetic analyses of the same genetic data set can yield conflicting results, depending on the choice of parameter settings and included taxa. This is particularly true in studies involving data sets where levels of homoplasy are high and likely to obscure the phylogenetic signal. Filtering of this phylogenetic noise can be attempted, with varying degrees of success, by using different weighting schemes and ingroup/outgroup choices, but it can be difficult to decide objectively which approach is best. Using a cytochrome b data set from cetaceans and artiodactyls, we examined the effects of a suite of parameter settings on the outcome of phylogenetic analyses. We tested 2968 combinations among the seven parameters that most often vary among phylogenetic studies. It is our contention that this sensitivity analysis identifies portions of the multidimensional parameter space where phylogenetic signal is most reliably recovered, and simple rules are given to guide the choice of settings. Portions of this data set have been used in previous studies with conflicting results, namely the monophyly vs. paraphyly of one of the two major recognized cetacean suborders, the toothed whales. This analysis strongly supports the sister relationship between sperm whales and baleen whales.

A rank-based nonparametric method for mapping quantitative trait loci in outbred half-sib pedigrees: application to milk production in a granddaughter design.

We describe the development of a multipoint nonparametric quantitative trait loci mapping method based on the Wilcoxon rank-sum test applicable to outbred half-sib pedigrees. The method has been evaluated on a simulated dataset and its efficiency compared with interval mapping by using regression. It was shown that the rank-based approach is slightly inferior to regression when the residual variance is homoscedastic normal; however, in three out of four other scenarios envisaged, i.e., residual variance heteroscedastic normal, homoscedastic skewed, and homoscedastic positively kurtosed, the latter outperforms the former one. Both methods were applied to a real data set analyzing the effect of bovine chromosome 6 on milk yield and composition by using a 125-cM map comprising 15 microsatellites and a granddaughter design counting 1158 Holstein-Friesian sires.

Real-time RT-PCR quantification of mRNA encoding cytokines and chemokines in histologically normal canine nasal, bronchial and pulmonary tissue.

Cytokines and chemokines are likely to be involved in the pathogenesis of inflammatory diseases of the canine respiratory tract. The roles and relative amounts of these molecules have not yet been defined in the respiratory mucosa of normal dogs or dogs with naturally acquired respiratory inflammation. In the present study, real-time reverse transcriptase polymerase chain reaction (RT-PCR) assays were employed to quantify messenger RNA (mRNA) encoding the chemokines monocyte chemotactic protein (MCP)-2, eotaxin-2 and eotaxin-3, and the cytokines interleukin-4 (IL-4), IL-5, IL-6, IL-10, IL-12p40, IL-18, interferon-gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta (TGF-beta) in normal nasal, bronchial and pulmonary tissues from puppies (n = 4) and from adult dogs (n = 7). There was no significant difference in the expression of any transcript between puppies and adult dogs at any of the anatomical sites examined. The expression of mRNA encoding eotaxin-2 and eotaxin-3 increased significantly with progression from the nasal mucosa to pulmonary parenchyma but expression of MCP-2 mRNA did not show this trend. At all levels of the respiratory mucosa, the most abundant transcripts were those encoding IL-18 and TGF-beta. Transcripts encoding IL-6, IL-10, IL-12 and TNF-alpha were approximately ten-fold less abundant, and IL-4, IL-5 and IFN-gamma were the least abundant templates. There was significantly different amount of mRNA encoding IL-5, IL-18 and TNF-alpha between particular anatomical levels of the respiratory mucosa while the mRNA expression of the other cytokines was similar at all anatomical sites. The results of the present study will enable comparisons to be made with results obtained from similar samples obtained from dogs with nasal, bronchial or pulmonary diseases.

Distribution of leucocyte subsets in the canine respiratory tract.

Histochemistry and immunohistochemistry were used to characterize leucocyte subsets in the respiratory tract of 15 outbred dogs (five aged <6 months and 10 aged >1 year) that had no evidence of respiratory disease. No organized nose- or bronchus-associated lymphoid tissue was observed in any of the sections examined. IgA(+) plasma cells predominated in nasal mucosa and in all parts of the bronchial tree, with fewer IgG(+) and IgM(+) plasma cells. The numbers of IgA(+) and IgM(+) cells were significantly greater in the nasal mucosa than in any other part of the respiratory mucosa. There were significantly fewer IgA(+), IgG(+) and IgM(+) cells in all parts of the respiratory tract in the puppies than in the adults. The number and distribution of mast cells and cells expressing MHC class II, L1 or CD1c were recorded. Mast cells were mainly found in the subepithelial lamina propria of nasal and bronchial mucosa and in the alveolar interstitium, and cells expressing IgE had a similar distribution. Mast cells were also present within muscle layers of the bronchial tree. The numbers of mast cells and MHC class II(+) cells were significantly greater in the nasal mucosa than in any other part of the respiratory mucosa. In the nose, carina and primary and secondary bronchus, there were significantly more mast cells and MHC class II(+) cells in puppies than in adult dogs, whereas the numbers of L1(+) cells and CD1c(+) cells in most sites were significantly greater in older dogs. There were significantly more CD3(+) and CD8(+) cells in the nasal mucosa than in any part of the bronchial mucosa. In most parts of the respiratory mucosa, CD4(+), CD8(+) and TCR alphabeta(+) cells were present in significantly greater numbers in adults than in puppies. All parts of the respiratory tract had similar numbers of mucosal CD4(+) and CD8(+) T lymphocytes. TCR gammadelta(+) cells were absent or sparse in all samples. These data, obtained from dogs without respiratory disease, will enable comparisons to be made with dogs suffering from infectious or inflammatory nasal, bronchial and pulmonary diseases.