Age-related alterations to immune parameters in Labrador retriever dogs

A revisiting of "the hallmarks of aging" in domestic dogs: current status of the literature

A progressive decline in biological function and fitness is, generally, how aging is defined. However, in 2013, a description on the "hallmarks of aging" in mammals was published, and within it, it described biological processes that are known to alter the aging phenotype. These include genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, altered intercellular communication (inflammation), and changes within the microbiome. This mini-review provides a detailed account of the progress on each of these hallmarks of aging in the domestic dog within the last 5 years. Additionally, when there are gaps in the literature between other mammalian species and dogs, I highlight the aging biomarkers that may be missing for dogs as aging models. I also argue for the importance of dog aging studies to include several breeds of dogs at differing ages and for age corrections for breeds with differing mean lifespans throughout.

Effects of Increasing Levels of Purified Beta-1,3/1,6-Glucans on the Fecal Microbiome, Digestibility, and Immunity Variables of Healthy Adult Dogs

Yeast-purified beta-1,3/1,6-glucans (BG) can modulate dogs' immune systems and microbiome, but the optimal inclusion dose remains unknown. The aim of the study was to evaluate the effects of 0.0, 0.07, 0.14, and 0.28% inclusion of BG in a dry extruded diet on the digestibility, immunity, and fecal microbiota of healthy adult dogs. Eight male and female border collies [n = 4; body condition score (BCS) = 5] and English cocker spaniels (n = 4; BCS = 5), aged 3.5 ± 0.5 years, were randomly distributed into two 4 × 4 balanced Latin squares. Fecal microbiota (using 16S rRNA sequencing, Illumina®), apparent digestibility coefficients (ADC) of nutrients, fecal concentrations of short-chain fatty acids (SCFA) and branched-chain fatty acids (BCFA), ammoniacal nitrogen, lactic acid, IgA and pH, lymphocyte immunophenotyping, intensity and percentage of phagocytosis and oxidative burst were determined. No differences were observed in Faith (p = 0.1414) and Pielou-evenness (p = 0.1151) between treatments, but beta diversity was different between 0.0% and 0.14% BG groups (p = 0.047). Moreover, the Firmicutes phylum was the most abundant in all groups and exhibited the highest relative abundance after the consumption of 0.14% BG, a finding considered beneficial for the canine microbiome. The Erysipelotrichaceae and Ruminococcaceae families, along with the Faecalibacterium and Prevotella genera, considered favorable for their involvement in butyrate production and other metabolites, showed increased abundance after the consumption of 0.14% BG. The potentially pathogenic Proteobacteria phylum displayed lower abundance after the consumption of 0.14% BG. Fecal concentrations of the evaluated compounds and pH did not differ after consumption of the BG at all percentages. Higher crude protein ADC was found after 0.14 and 0.28% BG consumption (p < 0.0001), but no differences were found for other nutrients. Phagocytosis, oxidative burst, and lymphocyte populations were not modulated by any of the treatments; however, 0.14% BG modulated the lymphocyte T CD4+:CD8+ ratio (p = 0.0368), an important marker of immune system efficiency. The inclusion of 0.14% BG resulted in the best responses and was the best dose evaluated.

Effect of Aging on the Immune Response to Core Vaccines in Senior and Geriatric Dogs

Elderly dogs are steadily increasing worldwide as well as veterinarians' and owners' interest in their health and wellness. Aging is not a disease, but a combination of changes negatively affecting the organism in general and the immune system in particular, resulting in a decline in protection over time. The aim of this study was to measure the specific serum antibody titers against the main dangerous and widespread viral diseases preventable by core vaccinations in senior and geriatric dogs using the in-practice test VacciCheck. A cohort of three hundred fifty elderly dogs was analyzed for Protective Antibody Titers (PATs) against CPV-2, CDV and CAdV-1. The age ranged from 5 to 19 years, with two hundred fifty-eight seniors (73.7%) and ninety-two geriatrics (26.3%), and 97.4% of them were vaccinated at least once in their lives. More than half of the entire study population (52.9%) had PATs simultaneously for all three diseases, with 80.5% seniors and 19.5% geriatrics. Specific PATs were found in 88.6% of aging dogs for CPV-2, 82.3% for CadV-1 and 66.0% for CDV, demonstrating that unprotected aging dogs represent a minority. Unexpectedly, the larger elderly dogs resulted as more protected than smaller ones for CPV-2. Protection then decreases over time, with geriatric dogs less protected than senior ones. Veterinary practitioners should therefore always consider whether to maintain core vaccinations in aging dogs as in adults on a three-year basis or opt instead for closer boosters (every 1 or 2 years). PATs for core vaccines could then represent a good biomarker of protection and their titration could become a standard of care, especially in such a sensitive period of the dogs' life.

Lymphocyte immunophenotyping in dogs with lymphopenia of common causes

Lymphocyte immunophenotyping can be useful for evaluating immune competence and predicting the disease prognosis. It is essential to gain knowledge about canine lymphocyte immunophenotypes in various conditions. The study deals with the characteristics of lymphopenia in dogs, with an emphasis on lymphocyte immunophenotyping by flow cytometry. Blood samples from 44 dogs with lymphopenia were included in the study. All lymphopenias sent from veterinary clinics to the diagnostic laboratory were analyzed. The hematological and biochemical abnormalities were investigated, as well as the effect of the age. Lymphopenias were classified according to the level of C-reactive protein (CRP). The percentage of T cells, B cells, T_h cells and T_c cells, and T/B and T_h/T_c ratios were determined by flow cytometry. Lymphopenias often occurred in dogs over 7 years of age (79.5 %). The most common were postoperative lymphopenia (31.8 %) and inflammatory diseases (29.5 %), most commonly affecting the gastrointestinal tract. Frequent abnormalities were monocytosis (56.8 %), increased CRP (72.7 %) and decreased albumin/globulin ratio (50.0 %). The percentage of T_h lymphocytes was significantly lower in the group with elevated CRP than in the group with basal CRP (P = 0.0329). A negative correlation was found between the level of CRP and the percentage of T_h lymphocytes (r = -0.3278, P = 0.0390). This study provided new insights into the appearance, incidence and classification of canine lymphopenia.

Infective endocarditis in dogs in the UK: 77 cases (2009-2019)

OBJECTIVES

To determine the causative organisms, clinical features and outcome of canine infective endocarditis in the UK.

MATERIALS AND METHODS

Medical records of three veterinary referral hospitals were searched for dogs with infective endocarditis between December 2009 and December 2019. Signalment, clinical signs, causative organism, valve affected, treatment and survival data were recorded.

RESULTS

Seventy-seven cases with possible or definite infective endocarditis (according to the modified Duke criteria) were included. The majority were large breed (40/77 - 51.9%). There were 47 of 77 (61%) male dogs and the mean age was 7.3 ±3 years. A causative organism was identified in 26 of 77 (33.8%) cases. The most common organisms were Escherichia coli (7/27 - 25.9%), Pasteurella spp. (5/27 - 18.5%), Staphylococcus spp. (4/27 - 14.8%) and Corynebacterium spp. (4/27 - 14.8%). Bartonella spp. were not detected in any patients. The mitral valve was most commonly affected (48/77 - 62.3%). Clinical features were non-specific, with lethargy being the most common clinical sign observed (53/77 - 68.8%). Fifty-three dogs (68.8%) survived to discharge. The median survival time post discharge was 425 days (2 to 3650 days). The development of congestive heart failure was associated with a poorer outcome. Cardiac troponin concentration, antithrombotic use and the development of thromboembolism or arrhythmias were not significantly associated with outcome.

CLINICAL SIGNIFICANCE

Some dogs with infective endocarditis that survive to discharge can have a long lifespan. The inability to detect an underlying organism is common and Bartonella spp. may be a less prevalent cause of canine infective endocarditis in the UK than in the USA.

Peripheral blood lymphocyte subtypes in dogs with different stages of myxomatous mitral valve disease

Background

Data on alterations in peripheral blood lymphocyte (PBL) subtypes in dogs with myxomatous mitral valve disease (MMVD) is lacking.

Objectives

To investigate PBL subtypes and their correlation with parameters of inflammation and MMVD progression markers in dogs with different stages of MMVD.

Animals

Seventy‐eight client‐owned dogs: 65 with MMVD (American College of Veterinary Internal Medicine [ACVIM] classification stages B2, C, and D) and 13 healthy controls.

Methods

Prospective cross‐sectional study. Complete cardiac assessment, flow cytometry (T lymphocytes [CD3+], their subtypes [CD3+CD4+, CD3+CD8+, CD3+CD4+CD8+, CD3+CD4−CD8−], and B lymphocytes [CD45+CD21+]) and measurement of N‐terminal pro B‐type natriuretic peptide, cardiac troponin I, and C‐reactive protein concentrations were performed.

Results

The percentage of CD3+CD4+ lymphocytes was significantly lower in stable ACVIM C patients (P = .01) and unstable ACVIM C and D patients (P = .003), the percentage of CD3+CD8+ lymphocytes was significantly higher in stable ACVIM C patients (P = .01) and unstable ACVIM C and D patients (P = .01), CD3+CD8+ lymphocyte concentration was significantly higher in unstable ACVIM C and D patients (P = .05), and the CD3+CD4+/CD3+CD8+ ratio was significantly lower in stable ACVIM C patients (P = .01) and unstable ACVIM C and D patients (P = .01) compared with healthy controls.

Conclusions and Clinical Importance

The percentages of CD3+CD4+ and CD3+CD8+ PBL and CD4+/CD8+ ratio were altered in MMVD dogs with congestive heart failure (ACVIM C, D), but not in ACVIM B2, suggesting involvement of these PBL subtypes in the pathogenesis of congestive heart failure in dogs with MMVD.

A review of the frequency and impact of periodontal disease in dogs

Periodontal disease is a frequent problem seen in veterinary practices. Primary-care veterinary practices, where diagnosis of periodontal disease is predominantly based on visual oral assessment of conscious dogs, report an average prevalence of 9.3 to 18.2% within the dog population. Detailed examinations of anaesthetised dogs report much higher prevalence of between 44 and 100%. The prevalence and severity of periodontitis varies between sizes of dogs, breeds and individuals. The lack of robust evaluation of these variances opens the opportunity for a review of the topic. A literature search was therefore undertaken to determine the frequency and extent (severity and oral location) of periodontal disease in the dog population. Both clinical and retrospective data based surveys of veterinary records, show there is an increased likelihood of developing periodontitis as age increases and with bodyweight decreases. The maxillary and mandibular incisors, fourth premolars and first molars are likely to develop the disease first although in some breeds the canines may also be involved. Poor oral care is a significant risk factor for the development of periodontal disease although diet, behaviour, environment and genetics are also likely to play a role. The information provided in this review can be used by veterinarians to improve the effectiveness of their diagnosis, treatments and interventions by focussing their efforts on the sizes, breeds and individuals most at risk. Given the potential link between periodontal disease and systemic health, veterinarians have the opportunity to positively impact the quality of life of a large number of dogs and therefore their owners.

Age-specific variations in hematological and biochemical parameters in middle- and large-sized of dogs

Aging triggers cellular and molecular alterations, including genomic instability and organ dysfunction, which increases the risk of disease in mammals. Recently, due to the markedly growing number of aging dogs in the world, as much as 49% in total number of pet dogs, it is necessary to improve and maintain their quality of life by understanding of the biological effects of aging. Therefore, the aim of this study was to determine specific biomarkers in aging dogs as a means of defining a set of hematological/biochemical biomarkers that influence the aging process. Blood samples were collected from younger (1-3 years) and older (7-10 years) dogs of middle/large size. The hematological/biochemistry analysis was performed to evaluate parameters significantly associated with age. Enzyme-linked immunosorbent assay was used to target growth hormone (GH)/insulin growth factor-1 (IGF-1), one of the main regulators of the aging process. Declining levels of total protein and increased levels of glucose in young dogs was observed regardless of their body size. Notably, a significantly high concentration of GH and IGF-1 in the younger dogs compared to the older dogs was found in middle/large-sized dogs. GH and IGF-1 were also found at significantly high levels in large-sized dogs compared to middle-sized dogs, suggesting a similar trend to that of elderly humans. Consequently, glucose, total protein, GH, and IGF-1 were identified as potential biomarkers for regulating the aging process in large/middle-sized dogs. These findings provide an invaluable insight into the mechanism of aging for the field of aging research.

Changes of ultrasonographic pattern of the spleen examined with a high-frequency linear transducer during growth in puppies

A normal spleen is a homogeneous, finely textured, and hyperechoic organ. The development of high-frequency transducers has enabled the examination of the structural features of the spleen. Thus, the spleen can appear mildly mottled, even in normal dogs, and this could be misinterpreted as an abnormality. The purpose of this prospective, longitudinal, descriptive study was to describe the ultrasonographic pattern of the splenic parenchyma using a high-frequency transducer in puppies. The study included nine, normal, client-owned puppies that were born healthy. Transabdominal ultrasonographic examination was performed from 4 to 60 weeks serially every 4 weeks. Ultrasonographic patterns of the spleen were graded as follows: granular, mild reticulonodular, moderate reticulonodular, and marked reticulonodular pattern. The examinations were performed by one veterinary clinician, and the grades of the ultrasonographic patterns were determined by two veterinary clinicians experienced in ultrasonography, based on consensus. Differences and associations between time and the grade of the splenic parenchyma were determined using the paired t-test and scatter plots. There was a strong quadratic relationship between time and the grade of the splenic parenchyma. It was found that the splenic parenchymal patterns changed with increasing age, with a granular appearance initially at 4 weeks, followed by a reticulonodular pattern with well-defined hypoechoic nodules-most marked between 28 and 36 weeks, after which this pattern decreased until there was a homogeneous granular pattern again at 60 weeks. These findings should not be misinterpreted as being indicative of a disease in normal puppies, particularly those aged between 28 and 36 weeks.

Active fractions of mannoproteins derived from yeast cell wall stimulate innate and acquired immunity of adult and elderly dogs

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Aging can promote changes in the immune system in dogs.

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Nutritional intervention in older dogs aims to increase lifespan.

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The yeast cell wall comprises β-(1,3)-D-glucan, β-(1,6)-D-glucan and mannoproteins.

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Elderly dogs when compared to adult dogs had lower absolute T and B lymphocyte counts.

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Mannoproteins stimulated acquired and innate immune responses in adult and elderly dogs.

Nutritional intervention in older dogs aims to increase lifespan and improve life quality as well as delay the development of diseases related to ageing. It is believed that active fractions of mannoproteins (AFMs) obtained through extraction and fractionation of yeast cell walls (Saccharomyces cerevisiae) may beneficially modulate the immune system. However, studies that have evaluated this component and the effects of ageing on the immune system of dogs are scarce. This study aimed to evaluate the immunological effects of AFMs in adult and elderly dogs. Three extruded iso-nutrient experimental diets were formulated: without addition of AFM (T0); with AFM at 400 mg/kg (T400); and with AFM at 800 mg/kg (T800). Thirty-six beagle dogs were used, and six experimental treatments, resulting in combinations of age (adult and elderly) and diet (T0, T400, and T800), were evaluated. On days zero, 14, and 28, blood samples were obtained for leucocyte phenotyping and phagocytosis assays. On days zero and 28, a lymphoproliferation test, quantification of reactive oxygen (H₂O₂) and nitrogen (NO) intermediate production, evaluation of faecal immunoglobulin A (IgA) content, and a delayed cutaneous hypersensitivity test (DCHT) were performed. Statistical analyses were performed with SAS software. Repeated measure variance analyses were performed, and means were compared by the Tukey test. Values of P ≤ 0.05 were considered significant, and values of P ≤ 0.10 were considered tendencies. Dogs fed T400 tended to have higher neutrophilic phagocytic activity than dogs fed T800 (P = 0.073). Regarding reactive oxygen intermediates, bacterial lipopolysaccharide (LPS)-stimulated neutrophils from animals that were fed T400 had a tendency to produce more H₂O₂ than those from animals fed the control diet (P = 0.093). Elderly dogs, when compared to adult dogs, had lower absolute T and B lymphocyte counts, lower auxiliary T lymphocyte counts, and higher cytotoxic T lymphocyte counts (P < 0.05). A significant effect of diet, age, and time with saline inoculation was noted for the DCHT. There was no effect of diet or age on faecal IgA content in dogs. This study suggests beneficial effects of mannoproteins on the specific and nonspecific immune responses in adult and elderly dogs.

Development of Dog Immune System: From in Uterus to Elderly

Immune system recognize and fight back foreign microorganisms and inner modifications that lead to deficient cell and tissue functions. During a dog's life, the immune system needs to adapt to different physiological conditions, assuring surveillance and protection in a careful and controlled way. Pregnancy alters normal homeostasis, requiring a balance between immunity and tolerance. The embryos and fetus should be protected from infections, while the female dog must tolerate the growing of semi-allografts in her uterus. After birth, newborn puppies are at great risk of developing infectious diseases, because their immune system is in development and immune memory is absent. Passive transfer of immunity through colostrum is fundamental for puppy survival in the first weeks of life, but hampers the development of an active immune response to vaccination. At the end of life, dogs experience a decline in the structure and functional competence of the immune system, compromising the immune responses to novel antigenic challenges, such as infections and vaccines. Therefore, the current article reviews the general processes related to the development of the dog´s immune system, providing an overview of immune activity throughout the dog's life and its implications in canine health, and highlighting priority research goals.

Does co-infection with vector-borne pathogens play a role in clinical canine leishmaniosis?

BACKGROUND

The severity of canine leishmaniosis (CanL) due to Leishmania infantum might be affected by other vector-borne organisms that mimic its clinical signs and clinicopathological abnormalities. The aim of this study was to determine co-infections with other vector-borne pathogens based on serological and molecular techniques in dogs with clinical leishmaniosis living in Spain and to associate them with clinical signs and clinicopathological abnormalities as well as disease severity.

METHODS

Sixty-one dogs with clinical leishmaniosis and 16 apparently healthy dogs were tested for Rickettsia conorii, Ehrlichia canis, Anaplasma phagocytophilum and Bartonella henselae antigens by the immunofluorescence antibody test (IFAT) and for E. canis, Anaplasma spp., Hepatozoon spp., Babesia spp. and filarioid DNA by polymerase chain reaction (PCR).

RESULTS

Among the dogs examined by IFAT, the seroprevalences were: 69% for R. conorii, 57% for E. canis, 44% for A. phagocytophilum and 37% for B. henselae; while the prevalences found by PCR were: 8% for Ehrlichia/Anaplasma, 3% for Anaplasma platys and 1% for H. canis. No other pathogen DNA was detected. Statistical association was found between dogs with clinical leishmaniosis and seroreactivity to R. conorii antigen (Fisher's exact test: P = 0.025, OR = 4.1, 95% CI = 1-17) and A. phagocytophilum antigen (Fisher's exact test: P = 0.002, OR = 14.3, 95% CI = 2-626) and being positive to more than one serological or molecular tests (co-infections) (Mann-Whitney test: U = 243, Z = -2.6, n ₁  = 14, n ₂  = 61, P = 0.01) when compared with healthy dogs. Interestingly, a statistical association was found between the presence of R. conorii, E. canis, A. phagocytophilum and B. henselae antibodies in sick dogs and some clinicopathological abnormalities such as albumin and albumin/globulin ratio decrease and increase in serum globulins. Furthermore, seroreactivity with A. phagocytophilum antigens was statistically associated with CanL clinical stages III and IV.

CONCLUSIONS

This study demonstrates that dogs with clinical leishmaniosis from Catalonia (Spain) have a higher rate of co-infections with other vector-borne pathogens when compared with healthy controls. Furthermore, positivity to some vector-borne pathogens was associated with more marked clinicopathological abnormalities as well as disease severity with CanL.

Evaluation of blood T-lymphocyte subpopulations involved in host cellular immunity in dogs with mammary cancer

Cancer-bearing patients are often immunosuppressed. In dogs with mammary or other cancers, various alterations in blood cell populations involved in host cellular immunity have been reported; among these cell populations some T-lymphocyte subsets play an important role against cancer. The purpose of the present study was to investigate any alterations in circulating T-lymphocyte subpopulations involved in cellular immunity in bitches with mammary cancer, in comparison to age-matched healthy intact bitches. Twenty eight dogs with mammary cancer and 14 control dogs were included in this study. Twelve out of the 28 bitches had mammary cancer of clinical stage II and 16/28 of stage III. Histological examination revealed that 23/28 animals had carcinomas, 3/28 sarcomas and 2/28 carcinosarcomas. White blood cell, neutrophil and lymphocyte absolute numbers were measured by complete blood count. Furthermore, blood T-lymphocyte population (CD3⁺) and the subpopulations CD4⁺, CD8⁺ and CD5^low+ were assessed by flow cytometry. White blood cell and neutrophil but not lymphocyte absolute numbers were higher (P=0.003 and P=0.001, respectively) in cancer patients than controls. Flow cytometric analysis revealed that the relative percentage of T-lymphocytes (CD3⁺) and of CD4⁺, CD8⁺ subpopulations was lower (the CD4⁺/CD8⁺ ratio was higher), whereas the percentage of CD5^low+ T-cells was higher, in dogs with cancer compared to controls; however, a statistically significant difference was found only in the case of CD8⁺ T-cells (P=0.014), whereas in the case of the CD4⁺/CD8⁺ ratio the difference almost reached statistical significance (P=0.059). Based on these findings, it can be suggested that, although the absolute number of blood lymphocytes is unchanged, the relative percentages of T-lymphocyte subpopulations involved in host cell-mediated immunity are altered, but only cytotoxic CD8⁺ T-cells are significantly suppressed, in dogs with mammary cancer of clinical stage II or III compared to age-matched healthy controls.

Hematology and biochemistry of aging-evidence of "anemia of the elderly" in old dogs

BACKGROUND

Effects of aging on hematologic and biochemical variables are well described in people. Anemia of the elderly is attributed to iron deficiency, anemia of chronic disease, chronic kidney disease, myelodysplasia, or idiopathic causes. Limited studies have examined these variables in aging dogs, but they have typically examined single breeds in research settings.

OBJECTIVE

The objective of this study was to identify differences in CBC and biochemistry values between adult and aged dogs of many breeds.

METHODS

Dogs presenting for wellness examinations and minor dental/elective surgeries that were otherwise clinically healthy were retrospectively identified. Dogs were categorized by age: adult (1-7.9 years), senior (8-11.9 years), and geriatric (12+ years). Standard CBC and biochemistry data were collated. Asian breeds, Greyhounds, and dogs with data indicating overt underlying disease were excluded. The Kruskal-Wallis test was used to compare groups with statistical significance set at P ≤ .05.

RESULTS

Hematocrit, MCV, and serum iron decreased with age, indicating possible iron-restricted erythropoiesis (IRE), due to iron deficiency or low-grade chronic inflammation. Total proteins, globulins, and platelet counts increased with age while albumin decreased, suggesting low-grade inflammation. Urea was increased in older dogs without a concurrent increase in creatinine, which points toward gastrointestinal bleeding or dehydration.

CONCLUSION

Clinically healthy, aging dogs have changes in laboratory variables that indicate altered physiologies compared to younger adult animals, including evidence of IRE, inflammation, and potential gastrointestinal bleeding, suggesting a similar trend to that of elderly human beings. Future studies will examine markers of iron metabolism and inflammation in aging dogs.

Gonadectomy effects on the risk of immune disorders in the dog: a retrospective study

BACKGROUND

Gonadectomy is one of the most common procedures performed on dogs in the United States. Neutering has been shown to reduce the risk for some diseases although recent reports suggest increased prevalence for structural disorders and some neoplasias. The relation between neuter status and autoimmune diseases has not been explored. This study evaluated the prevalence and risk of atopic dermatitis (ATOP), autoimmune hemolytic anemia (AIHA), canine myasthenia gravis (CMG), colitis (COL), hypoadrenocorticism (ADD), hypothyroidism (HYPO), immune-mediated polyarthritis (IMPA), immune-mediated thrombocytopenia (ITP), inflammatory bowel disease (IBD), lupus erythematosus (LUP), and pemphigus complex (PEMC), for intact females, intact males, neutered females, and neutered males. Pyometra (PYO) was evaluated as a control condition.

RESULTS

Patient records (90,090) from the William R. Pritchard Veterinary Medical Teaching Hospital at the University of California, Davis from 1995 to 2010 were analyzed in order to determine the risk of immune-mediated disease relative to neuter status in dogs. Neutered dogs had a significantly greater risk of ATOP, AIHA, ADD, HYPO, ITP, and IBD than intact dogs with neutered females being at greater risk than neutered males for all but AIHA and ADD. Neutered females, but not males, had a significantly greater risk of LUP than intact females. Pyometra was a greater risk for intact females.

CONCLUSIONS

The data underscore the importance of sex steroids on immune function emphasizing a role of these hormones on tissue self-recognition. Neutering is critically important for population control, reduction of reproductive disorders, and offers convenience for owners. Despite these advantages, the analyses of the present study suggest that neutering is associated with increased risk for certain autoimmune disorders and underscore the need for owners to consult with their veterinary practitioner prior to neutering to evaluate possible benefits and risks associated with such a procedure.

The effect of 1 year of trilostane treatment on peripheral lymphocyte subsets in dogs with pituitary-dependent hyperadrenocorticism

This study investigated the changes in lymphocyte subsets during the trilostane medication of Pituitary-dependent hyperadrenocorticism (PDH) dogs. The cortisol level and lymphocyte subsets of eight dogs with PDH were monitored 0, 1, 3, 6, 9 and 12 months after the initiation of trilostane treatment. White blood cells (WBC), lymphocytes, CD3⁺ (T lymphocyte), CD4⁺ (helper T lymphocyte), CD8⁺ (cytotoxic T lymphocyte) and CD21⁺ (B lymphocyte) cells were measured. Although the post-ACTH stimulation test cortisol level was significantly lower during trilostane treatment, changes in the CD3⁺, CD4⁺, CD8⁺ and CD21⁺ counts were not observed. Meanwhile, significant decrease was observed in WBC counts during trilostane treatment. These indicate that long-term trilostane treatment has little effect on the lymphocyte subsets in PDH dogs.

Peripheral leukocyte populations and oxidative stress biomarkers in aged dogs showing impaired cognitive abilities

In the present study, the peripheral blood leukocyte phenotypes, lymphocyte subset populations, and oxidative stress parameters were studied in cognitively characterized adult and aged dogs, in order to assess possible relationships between age, cognitive decline, and the immune status. Adult (N = 16, 2-7 years old) and aged (N = 29, older than 8 years) dogs underwent two testing procedures, for the assessment of spatial reversal learning and selective social attention abilities, which were shown to be sensitive to aging in pet dogs. Based on age and performance in cognitive testing, dogs were classified as adult not cognitively impaired (ADNI, N = 12), aged not cognitively impaired (AGNI, N = 19) and aged cognitively impaired (AGCI, N = 10). Immunological and oxidative stress parameters were compared across groups with the Kruskal-Wallis test. AGCI dogs displayed lower absolute CD4 cell count (p < 0.05) than ADNI and higher monocyte absolute count and percentage (p < 0.05) than AGNI whereas these parameters were not different between AGNI and ADNI. AGNI dogs had higher CD8 cell percentage than ADNI (p < 0.05). Both AGNI and AGCI dogs showed lower CD4/CD8 and CD21 count and percentage and higher neutrophil/lymphocyte and CD3/CD21 ratios (p < 0.05). None of the oxidative parameters showed any statistically significant difference among groups. These observations suggest that alterations in peripheral leukocyte populations may reflect age-related changes occurring within the central nervous system and disclose interesting perspectives for the dog as a model for studying the functional relationship between the nervous and immune systems during aging.

Selection based on indirect genetic effects for growth, environmental enrichment and coping style affect the immune status of pigs

Pigs living in intensive husbandry systems may experience both acute and chronic stress through standard management procedures and limitations in their physical and social environment, which may have implications for their immune status. Here, the effect of a new breeding method where pigs were selected on their heritable influence on their pen mates' growth, and environmental enrichment on the immune status of pigs was investigated. Hereto, 240 pigs with a relatively positive genetic effect on the growth of their pen mates (+SBV) and 240 pigs with a relatively negative genetic effect on the growth of their pen mates (-SBV) were housed in barren or straw-enriched pens from 4 to 23 weeks of age (n  =  80 pens in total). A blood sample was taken from the pigs before, three days after a 24 h regrouping test, and at week 22. In addition, effects of coping style, as assessed in a backtest, and gender were also investigated. Mainly, +SBV were found to have lower leukocyte, lymphocyte and haptoglobin concentrations than -SBV pigs. Enriched housed pigs had a lower neutrophil to lymphocyte (N:L) ratio and lower haptoglobin concentrations, but had higher antibody titers specific for Keyhole Limpet Hemocyanin (KLH) than barren housed pigs. No interactions were found between SBV class and housing. Furthermore, pigs with a proactive coping style had higher alternative complement activity and, in the enriched pens, higher antibody titers specific for KLH than pigs with a reactive coping style. Lastly, females tended to have lower leukocyte, but higher haptoglobin concentrations than castrated males. Overall, these results suggest that +SBV pigs and enriched housed pigs were less affected by stress than -SBV and barren housed pigs, respectively. Moreover, immune activation might be differently organized in individuals with different coping styles and to a lesser extent in individuals of opposite genders.

Immune profile predicts survival and reflects senescence in a small, long-lived mammal, the greater sac-winged bat (Saccopteryx bilineata)

The immune system imposes costs that may have to be traded against investment of resources in other costly life-history traits. Yet, it is unknown if a trade-off between immunity and longevity occurs in free-ranging mammals. Here, we tested if age and survival, two aspects associated with longevity, are linked to immune parameters in an 8 g bat species. Using a combination of cross-sectional and longitudinal data, we assessed whether total white blood cell (WBC) counts, bacterial killing ability of the plasma (BKA) and immunoglobulin G (IgG) concentration change with age. Furthermore, we asked if these immune parameters impose costs resulting in decreased survival probabilities. We found that WBC counts decreased with age both within and among individuals. IgG concentrations were higher in older individuals, but did not change with age within individuals. Furthermore, individuals with above average WBC counts or IgG concentration had lower probabilities to survive the next six months. High WBC counts and IgG concentrations may reflect infections with parasites and pathogens, however, individuals that were infected with trypanosomes or nematodes showed neither higher WBC counts or IgG concentrations, nor was infection connected with survival rates. BKA was higher in infected compared with uninfected bats, but not related to age or survival. In conclusion, cellular (WBC) and humoral (IgG) parts of the immune system were both connected to age and survival, but not to parasite infections, which supports the hypothesis that energetically costly immunological defences are traded against other costly life-history traits, leading to a reduced lifespan in this free-ranging mammal.

A longitudinal assessment of periodontal disease in 52 Miniature Schnauzers

Background

Periodontal disease (PD) is the most widespread oral disease in dogs and has been associated with serious systemic diseases. The disease is more prevalent in small breeds compared to large breeds and incidence increases with advancing age. In prevalence studies 84% of beagles over the age of 3 and 100% of poodles over the age of 4 were diagnosed with PD. Current knowledge of the rate of progression of PD is limited. The objective of this study was to determine the rate of PD progression in miniature schnauzers, an at risk small breed of dog.

Dogs (n = 52, age 1.3-6.9 years) who had received a regular oral care regime prior to this study were assessed for levels of gingivitis and periodontitis around the whole gingival margin in every tooth under general anaesthetic. Assessments were conducted approximately every six weeks for up to 60 weeks following the cessation of the oral care regime.

Results

All of the 2155 teeth assessed entered the study with some level of gingivitis. 23 teeth entered the study with periodontitis, observed across 12 dogs aged between 1.3 and 6.9 years. 35 dogs had at least 12 teeth progress to periodontitis within 60 weeks. Of the teeth that progressed to periodontitis, 54% were incisors. The lingual aspect of the incisors was significantly more likely to be affected (p < 0.001). The severity of gingivitis in periodontitis-affected teeth was variable with 24% of the aspects affected having very mild gingivitis, 36% mild gingivitis and 40% moderate gingivitis. Periodontitis progression rate was significantly faster in older dogs. Only one dog (age 3.5) did not have any teeth progress to periodontitis after 60 weeks.

Conclusions

This is the first study to have assessed the progression rate of periodontitis in miniature schnauzers and highlights that with no oral care regime, the early stages of periodontitis develop rapidly in this breed. An oral care regime and twice yearly veterinary dental health checks should be provided from an early age for this breed and other breeds with similar periodontitis incidence rates.

Alterations with age in peripheral blood lymphocyte subpopulations and cytokine synthesis in beagles

Purpose

The immune system is considered to be affected by aging, which is linked to various immune pathogeneses. The purpose of this study was to determine age-associated changes in immune function of healthy dogs (beagles), specifically those of naive and memory T lymphocytes, based on cytokine synthesis.

Patients and methods

Blood samples were obtained from 44 healthy beagles that were divided into three age-groups: young (<4 years), middle-aged (4-8 years), and older dogs (>8 years). Subpopulations of T lymphocytes were determined by flow cytometry. Transcriptional (mRNA) levels of cytokines were determined for primary-cultured leukocytes using quantitative real-time polymerase chain reaction.

Results

There were negative correlations between dogs' ages and the number of peripheral blood mononuclear cells, T cells, and B cells. In particular, the number of naive CD4⁺ CD45RA⁺ T cells and CD8⁺ CD45RA⁺ T cells significantly decreased with age. The mRNA levels for interleukin (IL)-2, IL-2Rα, and interferon-gamma were significantly higher in young or middle-aged dogs (P < 0.05), whereas IL-4 mRNA expression was not significantly different over the different age-groups. IL-2Rγ mRNA expression tended to decrease with age.

Conclusion

Decreases of naive CD4⁺ and naive CD8⁺ T cells may be related to age-related immunosenescence in dogs. With regard to cytokine production, leukocyte IL-4 and IL-10 mRNA levels did not change with age, whereas IL-2, IL-2Rα, and IL-2Rγ mRNA levels decreased with age. These altered cytokine mRNA expression patterns may contribute to decreased naive T-cell function(s) with aging.

Genome-wide association study identifies TNFSF13 as a susceptibility gene for IgA in a South Chinese population in smokers

IgA is an important factor in our immune system. There are many diseases associated with it, such as IgA nephropathy, IgA deficiency, and so on. In order to describe the relationship between the genes and the IgA level, we performed a genome-wide association study of serum IgA with 1,999 healthy Chinese men in the first stage and replicated on an independent Chinese sample with 1,496 subjects in the second stage. Association between each SNP with IgA was estimated by multivariate linear regression analysis conditioned on age and smoke. Haplotype analysis for the block around the top SNP was performed. In the first stage, one genomic locus was identified to be significantly associated with IgA. The loci is TNFSF13 (17p13.1; rs3803800; P = 6.26 × 10(-8)). In smoke-specific analysis, rs3803800 was approximately significantly associated with IgA levels in smokers (P = 3.96 × 10(-7)), while no association was observed in nonsmokers (P = 2.28 × 10(-1)). In addition, we performed the haplotype analysis on chromosome 17 with the SNPs around rs3803800. Although the total P value for the haplotype did not acquire significant difference, three haplotypes (TGAG, CACG, and CACA) reached significant (P < 0.05). In conclusion, TNFSF13 could be a susceptible gene which was discovered having relationship with serum IgA level, and smoke might be a factor infecting the IgA level.

Immunophenotypic evaluation of working Labrador Retrievers and German Shepherd dogs living in the same environment

Multiparametric flow cytometry was used to compare peripheral blood lymphocyte subset distribution between healthy working police Labrador Retrievers (LRs; n=12) and German Shepherd dogs (GS; n=11) living in the same environment. The CD4/CD8 ratio was significantly higher in LR than in GS because of the lower percentage of CD8+ T lymphocytes in LR. GS showed the highest relative percentage of CD3-/CD21- lymphocytes, whereas LR had the highest percentages of MHC II+ lymphocytes. Because age, sex, environmental and housing conditions, dietary patterns, and training or working routines were similar in both breeds in the study, differences in peripheral blood lymphocyte subset distribution could be attributed to the influence of breed on the immune system.

Faecal IgA concentration is influenced by age in dogs

Data comparing age-related alterations in faecal IgA concentrations of dogs are not available in the literature. The present study aimed to compare the faecal concentrations of IgA in puppies, mature and senior dogs. A total of twenty-four beagle dogs were used, including eight puppies (5 months old, four females and four males), eight mature (4·6 years old, eight males) and eight senior dogs (10·6 years old, three males and five females). Fresh faecal samples were collected from each dog for three consecutive days and pooled by animal. After saline extraction, IgA content was measured by ELISA. Data were analysed by one-way ANOVA, and means were compared with Tukey's test (P < 0·05). Results showed that puppies have lower faecal IgA concentrations than mature dogs (P < 0·05); senior animals presented intermediary results. The reduced faecal IgA concentration in puppies is consistent with the reduced serum and salivary IgA concentrations reported previously, suggesting a reduced mucosal immunity in this age group. Although some studies have found an increased serum IgA concentration in older dogs, this may differ from the intestinal secretion of IgA, which appears to be lower in some senior animals (four of the eight dogs studied).

Effect of a multi-species synbiotic formulation on fecal bacterial microbiota of healthy cats and dogs as evaluated by pyrosequencing

The effect of a multi-species synbiotic on the fecal microbiota of healthy cats (n = 12) and dogs (n = 12) was evaluated. The synbiotic (containing 5 × 10(9)  CFU of a mixture of seven probiotic strains, and a blend of fructooligosaccharides and arabinogalactans) was administered daily for 21 days. Fecal and serum samples were collected before, during, and up to 3 weeks after administration. Changes in the fecal microbiota were analyzed using denaturing gradient gel electrophoresis, 16S rRNA gene libraries, quantitative real-time PCR, and 16S rRNA gene 454-pyrosequencing. Probiotic species were detectable in 10/12 dogs and 11/12 cats during product administration. Abundances of Enterococcus and Streptococcus spp. were significantly increased in at least one time point during administration, and returned to baseline abundance after treatment was discontinued. No changes in the major bacterial phyla were identified on 454-pyrosequencing. No adverse gastrointestinal effects were recorded and no significant changes in gastrointestinal function or immune markers were observed during the study period. This study shows that while the ingestion of probiotics and prebiotics does not appear to alter the predominant bacterial phyla present in feces, supplementation with the investigated synbiotic leads to an increased abundance of probiotic bacteria in the feces of healthy cats and dogs.

Aged Beagle dogs have decreased neutrophil phagocytosis and neutrophil-related gene expression compared to younger dogs

Information on aging and the innate immune response in dogs is needed in order to understand the impact of age on the innate immune system and to design diets that might improve age-associated changes in innate immunity. The purpose of this study was to investigate the effects of age on phagocytosis and antibacterial activity of peripheral blood neutrophils, and on expression levels of selected mRNA specific for neutrophil migration or killing functions. Three groups of Beagle dogs were evaluated in a cross-sectional study design: puppies less than 1 year of age (n=15), adults 1-7 years of age (n=37) and senior adults over 8 years of age (n=25). Neutrophil phagocytosis and killing of Lactococcus lactis were assessed, and the relative abundance of mRNAs for myeloperoxidase (MPO), l-selectin, interleukin-8 receptor (IL-8R) and interleukin-1beta-converting enzyme (ICE) was determined. Results showed that in Beagle dogs there is a significant effect of age on percent bacterial killing by neutrophils. Average decline in phagocytic ability at 4 and 10 years of age (compared to 1 year of age) was 25% and 39%, respectively. In addition, younger dogs have significantly higher levels of mRNA for IL-8R, l-selectin and ICE. These results suggest that older dogs have depressed innate immune responses compared with younger dogs, which may contribute to increased morbidity and mortality with aging.

Age and long-term protective immunity in dogs and cats

Vaccination can provide an immune response that is similar in duration to that following a natural infection. In general, adaptive immunity to viruses develops earliest and is highly effective. Such anti-viral immune responses often result in the development of sterile immunity and the duration of immunity (DOI) is often lifelong. In contrast, adaptive immunity to bacteria, fungi or parasites develops more slowly and the DOI is generally short compared with most systemic viral infections. Sterile immunity to these infectious agents is less commonly engendered. Old dogs and cats rarely die from vaccine-preventable infectious disease, especially when they have been vaccinated and immunized as young adults (i.e. between 16 weeks and 1 year of age). However, young animals do die, often because vaccines were either not given or not given at an appropriate age (e.g. too early in life in the presence of maternally derived antibody [MDA]). More animals need to be vaccinated to increase herd (population) immunity. The present study examines the DOI for core viral vaccines in dogs that had not been revaccinated for as long as 9 years. These animals had serum antibody to canine distemper virus (CDV), canine parvovirus type 2 (CPV-2) and canine adenovirus type-1 (CAV-1) at levels considered protective and when challenged with these viruses, the dogs resisted infection and/or disease. Thus, even a single dose of modified live virus (MLV) canine core vaccines (against CDV, cav-2 and cpv-2) or MLV feline core vaccines (against feline parvovirus [FPV], feline calicivirus [FCV] and feline herpesvirus [FHV]), when administered at 16 weeks or older, could provide long-term immunity in a very high percentage of animals, while also increasing herd immunity.

Effect of ageing on the immune response of dogs to vaccines

Ageing is associated with a decline in functional competence of the immune system, sometimes referred to as immunosenescence. As this increases the susceptibility of dogs to infectious diseases, it is important to determine if the efficacy of vaccines is affected by ageing. Studies to date suggest that the primary response to vaccines may be compromised in old dogs, but recall responses remain intact. Information on the effect of ageing on the duration of protective immunity following vaccination is needed.

Immunophenotypical characterization in Andalusian horse: variations with age and gender

Assessment of lymphocyte subsets is an effective method for characterizing disorders such as leukemia, lymphomas, autoimmune and infectious diseases. In order to clinically interpret these parameters, normal reference values should be set, estimating age- and gender-related variations. This research aimed to: (1) characterize lymphocyte subpopulations in Andalusian horse, and (2) evaluate age and gender-related variations of lymphocyte subsets. Jugular blood samples were obtained from 159 animals, 77 males and 82 females, belonging to four age groups-1: 1-2 years (N=39; 21 males and 18 females), 2: 2-3 years (N=38; 16 males and 22 females), 3: 3-4 years (N=41; 19 males and 22 females) and 4: 4-7 years (N=41; 21 males and 20 females). T lymphocytes subsets were quantified by flow cytometry with monoclonal antibodies specific for CD2, CD4 and CD8 cell markers. B and NK cell counts were estimated by using a mathematical formula. No variations were found in T, B lymphocytes and NK cells between males and females. Animals of group 1 and 2 had a higher number of CD2, T, CD4+, CD8+, B lymphocytes and NK cells than animals of groups 3 and 4. The percentage of CD2 in group 1 was significantly lower than in group 4. The percentage of T and CD4+ lymphocytes in the group 1 were significantly higher than groups 2 and 3, respectively. Whereas the percentage of B cells calculated by flow cytometry was significantly lower in group 2 compared to group 4, the percentage of B cells calculated by a mathematical formula was higher in group 1. NK cells percentage was significantly lower in group 3 and 4 than in younger animals. In conclusion, in Andalusian horse, gender does not influence absolute numbers and percentages of T, B and NK. There is an age-related decline in absolute number of CD2, T, CD4+ and CD8+ lymphocytes, B lymphocytes and NK cells, with increasing percentage of CD2, T, CD4+ and B lymphocytes, and a decrease in NK with no differences in CD4/CD8 ratio. The decline of lymphocyte population numbers with age is a natural process in many animal species, and could be the origin for immune dysfunction observed in geriatric individuals.

An evolutionary perspective on the mechanisms of immunosenescence

There is an accumulating body of evidence that a decline in immune function with age is common to most if not all vertebrates. For instance, age-associated thymic involution seems to occur in all species that possess a thymus, indicating that this process is evolutionary ancient and conserved. The precise mechanisms regulating immunosenescence remain to be resolved, but much of what we do know is consistent with modern evolutionary theory. In this review, we assess our current knowledge from an evolutionary perspective on the occurrence of immunosenescence, we show that life history trade-offs play a key role and we highlight the possible advantages of the age-related decline in thymic function.

Assessing the immune state of dogs suffering from pituitary gland dependent hyperadrenocorticism by determining changes in peripheral lymphocyte subsets

In order to evaluate the immune state of dogs suffering from pituitary-dependent hyperadrenocorticism (PDH), peripheral lymphocyte subsets were examined. Twenty seven PDH dogs and eight healthy control dogs were used in the current study. Eight healthy dogs served as the control group. Twenty seven PDH dogs were categorized into 4 groups based on their post serum cortisol concentrations by ACTH stimulation test: 2-5, excellent control (n = 8); 5-20, fair control (n = 7); >20, poor control (n = 4); and untreated (n = 8). Cell counts were executed with white blood cells (WBC), lymphocytes, CD3(+) (T lymphocytes), CD4(+) (Helper T lymphocytes), CD8(+) (Cytotoxic T lymphocytes), CD21(+) (B lymphocytes) cells in addition to calculating CD4(+)/CD8(+) ratio. Results indicated a significant difference in lymphocyte numbers and lymphocyte subset populations (CD3(+), CD4(+), CD8(+), and CD21(+) cells) between PDH and control dogs. Moreover, comparison of the PDH groups (excellent control; fair control; poor control; untreated) demonstrated that all groups had a significant decrease in lymphocytes numbers (CD3(+), CD4(+) and CD21(+) cell counts) as compared to control group. Meanwhile, no significant differences were observed in WBC counts and CD4(+)/CD8(+) ratio between groups. Furthermore, lymphocyte subset distribution in excellent control PDH dogs without concurrent disease (n = 4) better resembled that of control dogs as compared to PDH dogs with concurrent disease (n = 4). PDH dogs may be suffering from an immuno-depressed state as evidenced by significant differences in lymphocyte subset populations. Furthermore, treatment of both PDH and concurrent disease might improve lymphocyte subset distribution.

Changes in peripheral lymphocyte subsets in the type 1 diabetic dogs treated with insulin injections

Plasma metabolites and peripheral lymphocyte subsets were measured in ten diabetic and ten control dogs to investigate their significances as indicators to evaluate immune states in the diabetic dogs. Diabetic dogs were treated with insulin injections, however their plasma glucose and fructosamine concentrations were significantly higher than those of the controls. There were no significant differences in counts of total white blood cells (WBC) and lymphocyte CD8(+) cells (cytotoxic T cells) between the control and the diabetic dogs. In the diabetic dogs, the counts of CD3(+) (T cells), CD4(+) (Helper T cells) and CD21(+) (B cells) cells and the peripheral lymphocytes CD4/CD8 ratio were significantly lower than those in the control dogs. We confirmed abnormality of lymphocyte subsets in insulin treated diabetic dogs and it may relate to depression of immunocompetence and high susceptibility to common infectious diseases.

Distribution of mast cell subtypes and immune cell populations in canine intestines: Evidence for age-related decline in T cells and macrophages and increase of IgA-positive plasma cells

The distribution and numbers of leucocytes and mast cells (MC) in the canine gastrointestinal tract of three different age groups was investigated immunhistochemically. In all age groups, CD3+ T cells were more prominent in the villus region than in the crypt areas without differences between intestinal segments, whereas macrophages were more randomly distributed. Kresylecht-violet and tryptase-positive MC were prominent in pericrypt regions with statistic significances. Chymase-bearing mast cells, IgA-, IgG- and IgM-containing cells did not show significant differences in their distribution but, except for IgG-positive cells, subjective trends with increasing numbers towards the crypts exist. The reasons for the distribution of T cells, macrophages, immunoglobulin-containing cells and mast cells are not clear. Lamina propria CD3+ T cells and macrophages significantly decreased whilst a significant increase of IgA-containing plasma cells with increasing age was found. For mast cell subtypes, IgG- and IgM-containing cells no significant changes in numbers with increasing age exist.

Lymphoid organ development in rabbits: major lymphocyte subsets

Although rabbits represent an important animal model, little is known about the lymphoid organ development in this species. In the present study, lymphocyte subsets in peripheral blood, spleen, mesenteric and popliteal lymph nodes in newborn and 2-, 4-, 6- and 8-week old and adult were characterized. Lymphocyte subsets were detected using flow cytometry and monoclonal antibodies against rabbit CD4, CD8, T-cell-specific antigen and cross-reactive antibody against B-cell antigen CD79alpha. In neonates, lower numbers of T cells were detected in both peripheral blood and spleen than in mesenteric lymph nodes. In comparison with other compartments, CD79alpha(+) cells prevailed in the spleen. Post-natal development was characterized by a decreased CD4(+)/CD8(+) ratio due to increasing frequency of CD8(+) lymphocytes in all organs but mesenteric lymph nodes, where it was due to decreased numbers of CD4(+) lymphocytes. Another significant feature was the increase of B cells in peripheral blood and mesenteric lymph nodes.