Prevalence and risk factors for common respiratory pathogens within a cohort of pet cats in the UK

OBJECTIVES

Feline herpesvirus (FHV), feline calicivirus (FCV) and Chlamydia felis are common causes of upper respiratory tract disease (URTD) in cats. Their prevalence in the UK pet cat population has not been reported and little is known regarding the risk factors for their oral carriage.

METHODS

Total nucleic acid was extracted from owner-collected buccal swabs (n=600) from cats enrolled in a self-selected longitudinal cohort study. Duplex quantitative PCRs for the detection of FHV and C. felis genomic DNA and reverse-transcriptase quantitative PCRs for the detection of FCV genomic RNA were performed. Duplicates, swabs with insufficient host DNA/RNA, and cats with missing data were excluded. Selected epidemiological data were interrogated using univariable and multi-variable logistic regression modelling to identify risk factors.

RESULTS

Data from 430 cats were included in the final statistical model. Of these, 2.1% (n=9/430; 95% CI 1.0% to 3.9%) were positive for FHV, 13.3% (n=57/430; 95% CI 10.2% to 16.8%) positive for FCV and 1.2% (n=5/430; 95% CI 0.4% to 2.7%) positive for C. felis. FCV co-infection was present in five (44%) FHV-positive cats and three (60%) C. felis-positive cats. FCV carriage was more frequent in purebred cats (odds ratio 2.48; 95% CI 1.37 to 4.49) and in cats with current or historical clinical signs compatible with URTD (odds ratio 2.98; 95% CI 1.22 to 7.27).

CLINICAL SIGNIFICANCE

FCV was the most frequently encountered URTD pathogen in this sample of cats; this should be noted for disinfectant choice. In cats suspected of having FHV or C. felis infection, assessment for co-infection with FCV is recommended.

A Crohn's Disease-associated IL2RA Enhancer Variant Determines the Balance of T Cell Immunity by Regulating Responsiveness to IL-2 Signalling

BACKGROUND AND AIMS

Differential responsiveness to interleukin [IL]-2 between effector CD4+ T cells [Teff] and regulatory T cells [Treg] is a fundamental mechanism of immunoregulation. The single nucleotide polymorphism [SNP] rs61839660, located within IL2RA [CD25], has been associated with the development of Crohn's disease [CD]. We sought to identify the T cell immune phenotype of IBD patients who carry this SNP.

METHODS

Teff and Treg were isolated from individuals homozygous [TT], heterozygous [CT], or wild-type [CC] for the minor allele at rs61839660, and used for phenotyping [flow cytometry, Cytometry Time Of Flight] functional assays or T cell receptor [TCR] sequencing. Phosphorylation of signal transducer and activator of transcription 5 [STAT5] was assessed in response to IL-2, IL-7, and in the presence of basiliximab, a monoclonal antibody directed against CD25. Teff pro-inflammatory cytokine expression levels were assessed by reverse transcription quantitative polymerase chain reaction after IL-2 and/or TCR stimulation.

RESULTS

Presence of the minor T allele enhances CD25 expression, leading to increased STAT5 phosphorylation and pro-inflammatory cytokine transcript expression by Teff in response to IL-2 stimulation in vitro. Teff from TT individuals demonstrate a more activated gut homing phenotype. TCR sequencing analysis suggests that TT patients may have a reduced clonal capacity to mount an optimal regulatory T cell response.

CONCLUSIONS

rs61839660 regulates the responsiveness of T cells to IL-2 signalling by modulating CD25 expression. As low-dose IL-2 is being trialled as a selective Treg modulator in CD, these findings highlight the potential for adverse effects in patients with this genotype.

Regulatory T-cell therapy in Crohn's disease: challenges and advances

The prevalence of IBD is rising in the Western world. Despite an increasing repertoire of therapeutic targets, a significant proportion of patients suffer chronic morbidity. Studies in mice and humans have highlighted the critical role of regulatory T cells in immune homeostasis, with defects in number and suppressive function of regulatory T cells seen in patients with Crohn's disease. We review the function of regulatory T cells and the pathways by which they exert immune tolerance in the intestinal mucosa. We explore the principles and challenges of manufacturing a cell therapy, and discuss clinical trial evidence to date for their safety and efficacy in human disease, with particular focus on the development of a regulatory T-cell therapy for Crohn's disease.

Thyroid and renal function in cats following low-dose radioiodine (111Mbq) therapy

OBJECTIVES

To describe the effect of low-dose (111MBq) radioiodine therapy on thyroid and renal function in hyperthyroid cats over a 12-month follow-up period.

MATERIALS AND METHODS

Client-owned hyperthyroid cats underwent low-dose radioiodine therapy and were followed-up for 12 months. Immediately before radioiodine treatment, and at 1, 6 and 12 months afterwards, total thyroxine, thyroid stimulating hormone, serum creatinine and glomerular filtration rate were measured.

RESULTS

Fifteen of the 24 (63%) cats achieved euthyroidism following low-dose radioiodine treatment. The incidence of overt hypothyroidism was six of 24 (25%) cats. Of the six cats developing overt hypothyroidism, three had decreased renal function, with decreased glomerular filtration rate preceding azotaemia in two of these individuals. Transient overt or subclinical hypothyroidism before restoration of euthyroidism was not observed.

CLINICAL SIGNIFICANCE

Low-dose radioiodine is effective treatment for hyperthyroidism in most cats but overt hypothyroidism may develop in some. Concurrent early decline in renal function may only be detected by measuring glomerular filtration rate rather than serum creatinine in some cats. Monitoring following radioiodine treatment should include total thyroxine and thyroid stimulating hormone and measurement of glomerular filtration rate should be considered in non-azotaemic cats.

Correction of Defective T-Regulatory Cells From Patients With Crohn's Disease by Ex Vivo Ligation of Retinoic Acid Receptor-α

BACKGROUND & AIMS

Crohn's disease (CD) is characterized by an imbalance of effector and regulatory T cells in the intestinal mucosa. The efficacy of anti-adhesion therapies led us to investigate whether impaired trafficking of T-regulatory (Treg) cells contributes to the pathogenesis of CD. We also investigated whether proper function could be restored to Treg cells by ex vivo expansion in the presence of factors that activate their regulatory activities.

METHODS

We measured levels of the integrin α4β7 on Treg cells isolated from peripheral blood or lamina propria of patients with CD and healthy individuals (controls). Treg cells were expanded ex vivo and incubated with rapamycin with or without agonists of the retinoic acid receptor-α (RARA), and their gene expression profiles were analyzed. We also studied the cells in cytokine challenge, suppression, and flow chamber assays and in SCID mice with human intestinal xenografts.

RESULTS

We found that Treg cells from patients with CD express lower levels of the integrin α4β7 than Treg cells from control patients. The pathway that regulates the expression of integrin subunit α is induced by retinoic acid (RA). Treg cells from patients with CD incubated with rapamycin and an agonist of RARA (RAR568) expressed high levels of integrin α4β7, as well as CD62L and FOXP3, compared with cells incubated with rapamycin or rapamycin and all-trans retinoic acid. These Treg cells had increased suppressive activities in assays and migrated under conditions of shear flow; they did not produce inflammatory cytokines, and RAR568 had no effect on cell stability or lineage commitment. Fluorescently labeled Treg cells incubated with RAR568 were significantly more likely to traffic to intestinal xenografts than Treg cells expanded in control medium.

CONCLUSIONS

Treg cells from patients with CD express lower levels of the integrin α4β7 than Treg cells from control patients. Incubation of patients' ex vivo expanded Treg cells with rapamycin and an RARA agonist induced expression of α4β7 and had suppressive and migratory activities in culture and in intestinal xenografts in mice. These cells might be developed for treatment of CD. ClinicalTrials.gov, Number: NCT03185000.

Inflammatory Mediators in the Mesenteric Lymph Nodes, Site of a Possible Intermediate Phase in the Immune Response to Feline Coronavirus and the Pathogenesis of Feline Infectious Peritonitis?

Feline infectious peritonitis (FIP) is an almost invariably fatal feline coronavirus (FCoV)-induced disease thought to arise from a combination of viral mutations and an overexuberant immune response. Natural initial enteric FCoV infection may remain subclinical, or result in mild enteric signs or the development of FIP; cats may also carry the virus systemically with no adverse effect. This study screened mesenteric lymph nodes (MLNs), the presumed first site of FCoV spread from the intestine regardless of viraemia, for changes in the transcription of a panel of innate immune response mediators in response to systemic FCoV infection and with FIP, aiming to identify key pathways triggered by FCoV. Cats with and without FIP, the latter with and without FCoV infection in the MLN, were compared. Higher expression levels in FIP were found for toll-like receptors (TLRs) 2, 4 and 8. These are part of the first line of defence and suggest a response to both viral structural proteins and viral nucleic acid. Expression of genes encoding inflammatory cytokines and chemokines, including interleukin (IL)-1β, IL-6, IL-15, tumour necrosis factor (TNF)-α, CXCL10, CCL8, interferon (IFN)-α, IFN-β and IFN-γ, was higher in cats with FIP, consistent with inflammatory pathway activation. Expression of genes encoding transcription factors STAT1 and 2, regulating signalling pathways, particularly of the interferons, was also higher. Among cats without FIP, there were few differences between virus-positive and virus-negative MLNs; however, TLR9 and STAT2 expression were higher with infection, suggesting a direct viral effect. The study provides evidence for TLR involvement in the response to FCoV. This could open up new avenues for therapeutic approaches.

Prevalence and distribution of Borrelia and Babesia species in ticks feeding on dogs in the U.K

Ticks were collected during March-July 2015 from dogs by veterinarians throughout the U.K. and used to estimate current prevalences and distributions of pathogens. DNA was extracted from 4750 ticks and subjected to polymerase chain reaction and sequence analysis to identify Borrelia burgdorferi sensu lato (Spirochaetales: Spirochaetaceae) and Babesia (Piroplasmida: Babesiidae) species. Of 4737 ticks [predominantly Ixodes ricinus Linneaus (Ixodida: Ixodidae)], B. burgdorferi s.l. was detected in 94 (2.0%). Four Borrelia genospecies were identified: Borrelia garinii (41.5%); Borrelia afzelli (31.9%); Borrelia burgdorferi sensu stricto (25.5%), and Borrelia spielmanii (1.1%). One Rhipicephalus sanguineus Latreille (Ixodida: Ixodidae), collected from a dog with a history of travel outside the U.K., was positive for B. garinii. Seventy ticks (1.5%) were positive for Babesia spp. Of these, 84.3% were positive for Babesia venatorum, 10.0% for Babesia vulpes sp. nov., 2.9% for Babesia divergens/Babesia capreoli and 1.4% for Babesia microti. One isolate of Babesia canis was detected in a Dermacentor reticulatus (Ixodida: Ixodidae) tick collected from a dog that had recently travelled to France. Prevalences of B. burgdorferi s.l. and Babesia spp. did not differ significantly between different regions of the U.K. The results map the widespread distribution of B. burgdorferi s.l. and Babesia spp. in ticks in the U.K. and highlight the potential for the introduction and establishment of exotic ticks and tick-borne pathogens.

The use of real-time PCR in the diagnosis and monitoring of Mycoplasma haemofelis copy number in a naturally infected cat

A 5-year-old male neutered cat was diagnosed with severe anaemia due to acute Mycoplasma haemofelis infection. Inflammatory respiratory disease was present concurrently. The cat was treated successfully using a fresh transfusion of whole blood and a 6 week course of doxycycline. The patient made a rapid recovery although the allergic airway disease subsequently required specific therapy consisting of inhaled fluticasone and salbutamol. Real-time quantitative PCR assays confirmed the presence of M. haemofelis DNA copies in the blood at presentation. Repeat PCR assays showed a reduction in copy number during treatment and negative PCR results were obtained both 91 and 425 days after presentation. The report describes, for the first time, the use of real-time PCR in the diagnosis and monitoring of natural M. haemofelis copy number, as well as the induction of long-term negative PCR status.

Analysis of risk factors and prevalence of haemoplasma infection in dogs

Mycoplasma haemocanis (Mhc) and 'Candidatus Mycoplasma haematoparvum' (CMhp) are canine haemoplasma species that can induce anaemia in immunocompromised and/or splenectomised dogs. This study aimed to determine the prevalence and phylogeny of canine haemoplasma species in dogs from Nigeria and describe any risk factors for infection. Canine haemoplasma species-specific and generic haemoplasma qPCR assays were used. The species-specific qPCR assays found Mhc infection in 18 of 245 dogs (7.3%), and CMhp infection in only one dog (0.4%). The generic haemoplasma qPCR assays were positive in 44 of 245 (17.9%) dogs. Twenty-five dogs had discordant qPCR results in that they were generic haemoplasma qPCR positive but species-specific qPCR negative. Further evaluation of these dogs by 16S rDNA sequencing gave limited results but 5 were confirmed to be infected with non-haemoplasma species: 2 Anaplasma phagocytophilum, 1 Anaplasma ovis, 1 Serratia marcescens and 1 Aerococcus spp. The 16S rRNA gene sequences from Mhc species showed>99.8% identity with each other and>99.6% identity with GenBank sequences, and resided in a single clade with other global Mhc and Mycoplasma haemofelis sequences, indicating low 16S rRNA genetic variability amongst this canine haemoplasma species.

Analysis of risk factors and prevalence of haemoplasma infection in dogs

Mycoplasma haemocanis (Mhc) and 'Candidatus Mycoplasma haematoparvum' (CMhp) are canine haemoplasma species that can induce anaemia in immunocompromised and/or splenectomised dogs. This study aimed to determine the prevalence and phylogeny of canine haemoplasma species in dogs from Nigeria and describe any risk factors for infection. Canine haemoplasma species-specific and generic haemoplasma qPCR assays were used. The species-specific qPCR assays found Mhc infection in 18 of 245 dogs (7.3%), and CMhp infection in only one dog (0.4%). The generic haemoplasma qPCR assays were positive in 44 of 245 (17.9%) dogs. Twenty-five dogs had discordant qPCR results in that they were generic haemoplasma qPCR positive but species-specific qPCR negative. Further evaluation of these dogs by 16S rDNA sequencing gave limited results but 5 were confirmed to be infected with non-haemoplasma species: 2 Anaplasma phagocytophilum, 1 Anaplasma ovis, 1 Serratia marcescens and 1 Aerococcus spp. The 16S rRNA gene sequences from Mhc species showed>99.8% identity with each other and>99.6% identity with GenBank sequences, and resided in a single clade with other global Mhc and Mycoplasma haemofelis sequences, indicating low 16S rRNA genetic variability amongst this canine haemoplasma species.

Feline blood genotyping versus phenotyping, and detection of non-AB blood type incompatibilities in UK cats

OBJECTIVES

The aim of this study was to determine the agreement between AB blood phenotyping and genotyping and determine whether non-AB blood type incompatibilities exist in UK cats.

METHODS

Blood samples underwent phenotyping (A, B or AB) using microplate agglutination, and genotyping (AA, Ab or bb) using pyrosequencing of a fragment of the cytidine monophospho-N-acetylneuraminic acid hydroxylase gene. Non-AB blood type incompatibilities were investigated by cross-matching against reference blood of the same phenotype.

RESULTS

Of 112 cats tested, 86 (77%) were blood phenotype A, 19 (17%) type B and 7 (6%) type AB. Genotype and initial phenotype agreed in 96% (107 of 112) of cats, but 5 were discordant; these were all B phenotype with either AA (n=2) or Ab (n=3) genotype. Two of the five cats had repeat blood samples tested: one was reclassified as phenotype A; the other remained phenotype B. Two cats had incompatibilities on minor cross-match, but these were attributed to phenotyping errors.

CLINICAL SIGNIFICANCE

Unknown mutation(s) associated with phenotype B, resulting in false AA or Ab genotyping, were evident in a small number of cases in this study. No conclusive evidence for non-AB blood type incompatibilities was found.

Infectious agent screening in canine blood donors in the United Kingdom

OBJECTIVES

Transfusion of blood products is an important component of veterinary emergency medicine. Donors must be carefully selected to minimise risk of transmission of blood-borne infectious agents. This study was devised to assess the prevalence of such agents in healthy, non-travelled UK dogs screened as prospective donors.

METHODS

Ethylenediaminetetraacetic acid blood samples from dogs donating blood between August 2007 and January 2012 were screened by polymerase chain reaction for haemotropic mycoplasmas, Bartonella, Babesia, Leishmania, Ehrlichia and Anaplasma spp. Dogs with positive or inconclusive results underwent repeat polymerase chain reaction testing.

RESULTS

Four of 262 dogs had positive or inconclusive results at initial screening. Repeat polymerase chain reaction testing in each dog was negative, and none of the dogs developed clinical signs of disease.

CLINICAL SIGNIFICANCE

The positive results on initial screening may have represented false positives from sample contamination or amplification of non-target DNA. It is also possible that dogs were infected at initial sampling but successfully cleared infection before repeat testing. The low number of positive results obtained suggests that prevalence of these agents in a population of healthy UK dogs is low and that use of blood products is unlikely to represent a significant risk of transmission of these diseases.

Non-ribosomal phylogenetic exploration of Mollicute species: new insights into haemoplasma taxonomy

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The first gapA and dnaK phylogenetic analysis of Mollicute species.

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Analysis includes a wide range of haemoplasmas species.

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Analysis supports that haemoplasmas reside within a single clade.

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Evidence of phylogenetic distance between the haemoplasmas and Mycoplasma species.

Nine species of uncultivable haemoplasmas and several Mycoplasma species were examined by partial sequencing of two protein-encoding housekeeping genes. Partial glyceraldehyde-3-phosphate dehydrogenase (gapA) and heat shock protein 70 (dnaK) gene sequences were determined for these Mollicute species; in total nine gapA sequences and ten dnaK sequences were obtained. Phylogenetic analyses of these sequences, along with those of a broad selection of Mollicute species downloaded from GenBank, for the individual genes, and for the gapA and dnaK concatenated data set, revealed a clear separation of the haemoplasmas from other species within the Mycoplasma genus; indeed the haemoplasmas resided within a single clade which was phylogenetically detached from the pneumoniae group of Mycoplasmas. This is the first report to examine the use of gapA and dnaK, as well as a concatenated data set, for phylogenetic analysis of the haemoplasmas and other Mollicute species. These results demonstrate a distinct phylogenetic separation between the haemoplasmas and Mycoplasmas that corresponds with the biological differences observed in these species, indicating that further evaluation of the haemoplasmas’ relationship with the Mycoplasma genus is required to determine whether reclassification of the haemoplasmas is necessary.

Cats with inflammatory bowel disease and intestinal small cell lymphoma have low serum concentrations of 25-hydroxyvitamin D

Background

Inflammatory bowel disease (IBD) and intestinal small cell lymphoma (ISCL) are common diseases in cats. The prevalence of alterations in the serum concentrations of fat soluble vitamins, such as vitamin D, in cats with IBD and ISCL is unknown.

Hypothesis/Objectives

The objective of this study was to measure serum 25 hydroxyvitamin D (25[OH]D) concentrations in cats with IBD or ISCL. Serum 25(OH)D also was measured in healthy cats, and in hospitalized ill cats with nongastrointestinal diseases.

Animals

Eighty‐four cats were included in the study: 23 in the healthy group, 41 in the hospitalized ill group, and 20 in the IBD/ISCL group.

Methods

Retrospective study. Serum samples for vitamin D analysis were frozen at −20°C until serum 25(OH)D was measured by high‐performance liquid chromatography (HPLC).

Results

Although there was overlap in serum 25(OH)D concentrations among the 3 groups, serum 25(OH)D concentrations were significantly lower in the cats with IBD or ISCL compared to healthy cats (P < .0001) and hospitalized ill cats (P = .014). In the IBD/ISCL group, there was a significant moderate positive correlation between serum albumin and 25(OH)D concentrations (r = 0.58, P = .018).

Conclusion and Clinical Importance

The median serum concentration of 25(OH)D was significantly lower in cats with IBD/ISCL than in healthy cats and in hospitalized ill cats. Additional studies are required to elucidate the mechanism of hypovitaminosis D in cats with gastrointestinal diseases, to define the best management strategy to treat this complication, and to investigate its potential prognostic implications.

Phylogenetic analysis of feline coronavirus strains in an epizootic outbreak of feline infectious peritonitis

Background

Feline coronavirus (FCoV) infection is common. In a small percentage of cats, FCoV infection is associated with the fatal disease feline infectious peritonitis (FIP). Genetically distinct virulent and avirulent strains of FCoV might coexist within a cat population.

Objectives

To determine whether the strains of FCoV in FIP‐affected cats are closely related or genetically distinct from the fecally derived strains of FCoV in contemporary‐asymptomatic cats during an epizootic outbreak of FIP.

Animals

Four cats euthanized because of FIP and 16 asymptomatic cats.

Methods

This prospective outbreak investigation was initiated during an outbreak of FIP in cats within or rehomed from a rescue/rehoming center. Postmortem samples were collected from cats with FIP and contemporaneous fecal samples from asymptomatic cats. RNA was purified from tissue and fecal samples, FCoV gene fragments were reverse transcribed, PCR‐amplified using novel primers, and sequenced. Sequences were aligned with ClustalW and compared with published FCoV sequences.

Results

FCoV RNA was detected in all 4 FIP cat postmortem samples and in 9 of the 16 fecal samples from contemporary‐asymptomatic cats. Novel primers successfully amplified fragments from 4 regions of the genome for all FCoV‐positive samples. Phylogenetic analysis showed that the FIP‐associated strains of FCoV from the outbreak were very closely related to the fecally derived strains of FCoV from contemporary‐asymptomatic cats.

Conclusions and Clinical Importance

Sequence analysis provided no evidence that genetically distinct virulent and avirulent strains of FCoV were present during this FIP outbreak.

Haemoplasmas: lessons learnt from cats

The haemotropic mycoplasmas (haemoplasmas) are a group of bacteria that can induce anaemia in a wide variety of mammals, including domestic cats and wild felids. Different feline haemoplasma species of varying pathogenicity exist, with the more pathogenic Mycoplasma haemofelis (Mhf) capable of inducing severe haemolytic anaemia, whilst 'Candidatus Mycoplasma haemominutum' (CMhm) and 'Candidatus Mycoplasma turicensis' (CMt) are infrequently associated with clinical disease. Chronic haemoplasma infections are common and cats are frequently infected by two or more haemoplasmas, complicating the clinical picture. The natural route of transmission of haemoplasma infection between cats has not yet been determined; however, experimental transmission has been demonstrated via both oral and parenteral administration of infected blood. To date the haemoplasmas have been unable to be cultured in vitro, and accurate diagnosis is currently reliant on detection of bacterial DNA using PCR assays. Treatment of clinical haemoplasmosis is focussed on supportive care in combination with empirical treatment with antimicrobials (tetracyclines or fluoroquinolones). A significant number of asymptomatic cats are positive for haemoplasma infection. These cats may play a role in the maintenance of haemoplasma infection within a population, and need to be considered when choosing potential blood donors. Use of PCR assays has provided an accurate method of diagnosing haemoplasma infection and quantifying response to therapy, including in non-feline host animals, as presumed zoonotic haemoplasma infections are now being documented. Recent advances in genome sequencing techniques have allowed the whole genome sequences of the feline haemoplasmas Mhf and CMhm to be derived, as well as a number of non-feline haemoplasma species. These data have aided the identification of antigens for use in the development of serological tests, allowed the proteomic study of haemoplasmas and provided clues as to how the haemoplasmas can persist within the host. Future areas of study include investigation of their zoonotic potential, mechanisms of immune system evasion and transmission of these emerging pathogens.

Acute phase response to Mycoplasma haemofelis and 'Candidatus Mycoplasma haemominutum' infection in FIV-infected and non-FIV-infected cats

The pathogenicity of Haemoplasma spp. in cats varies with 'Candidatus Mycoplasma haemominutum' (CMhm) causing subclinical infection while Mycoplasma haemofelis (Mhf) often induces haemolytic anaemia. The aims of this study were to characterise the acute phase response (APR) of the cat to experimental infection with Mhf or CMhm, and to determine whether chronic feline immunodeficiency virus (FIV) infection influences this response. The acute phase proteins serum amyloid A (SAA), haptoglobin (Hp) and α-1-acid glycoprotein (AGP) concentrations were measured pre-infection and every 7-14 days up to day 100 post-infection (pi) in cats infected with either Mhf or CMhm. Half of each group of cats (6/12) were chronically and subclinically infected with FIV. Marbofloxacin treatment was given on days 16-44 pi to half of the Mhf-infected cats, and on days 49-77 pi to half of the CMhm-infected cats. FIV-infected animals had significantly lower AGP concentrations, and significantly greater Hp concentrations than non-FIV-infected cats when infected with CMhm and Mhf, respectively. Both CMhm and Mhf infection were associated with significant increases in SAA concentrations, while AGP concentrations were only significantly increased by Mhf infection. Mhf-infected cats had significantly greater SAA concentrations than CMhm-infected animals. Both Mhf and CMhm infections were associated with an APR, with Mhf infection inducing a greater response. Chronic FIV infection appeared to modify the APR, which varied with the infecting Haemoplasma species.

Real-time quantitative polymerase chain reaction detection of haemoplasmas in healthy and unhealthy dogs from Central Macedonia, Greece

OBJECTIVES

The aims of this study were to determine the prevalence of canine haemoplasmas, Mycoplasma haemocanis and "Candidatus Mycoplasma haematoparvum" infection in Central Macedonia, Greece, and to evaluate any associations between canine haemoplasma infection and clinical presentation, selected laboratory data or the presence of ticks.

METHODS

Genomic DNA was purified from excess blood (n=151) submitted for haematological examination. Purified DNA was subjected to species-specific quantitative polymerase chain reaction assays duplexed with a canine DNA control quantitative polymerase chain reaction. Clinical records were retrospectively examined and selected clinical parameters were compared to haemoplasma infection status.

RESULTS

Nine samples were excluded due to inadequate canine DNA polymerase chain reaction results. Of the remaining 142 samples: eight (5·6%) were positive for M. haemocanis alone, six (4·2%) were positive for "Ca. M. haematoparvum" alone and one (0·7%) was dual positive. No association was found between haemoplasma status and age, sex, breed, health status, presence of anaemia, selected biochemistry parameters, presence of ectoparasites, routine ectoparasiticide treatment or the presence of selected tick-borne diseases.

Haemoplasma infection is not a common cause of canine immune-mediated haemolytic anaemia in the UK

OBJECTIVE

The aim of this study was to investigate whether the two canine haemoplasma species, Mycoplasma haemocanis and "Candidatus Mycoplasma haematoparvum," are commonly associated with immune-mediated haemolytic anaemia (IMHA) in UK dogs.

METHODS

Three groups of dogs were recruited to the study: anaemic dogs with primary IMHA (n=37); anaemic dogs not meeting the inclusion criteria for primary IMHA (n=77) and non-anaemic dogs (n=113). DNA was extracted from 100 μl of blood and subjected to real-time quantitative polymerase chain reaction (qPCR) assays for both species of Mycoplasma. Each assay incorporated co-amplification of canine glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as an endogenous internal control.

RESULTS

Canine GAPDH was successfully amplified by qPCR from all 227 canine blood samples but none contained M. haemocanis or "Candidatus M. haematoparvum" DNA.

CLINICAL SIGNIFICANCE

Haemoplasma infection is uncommon in dogs in the UK and no evidence was found that these organisms act as triggers for IMHA.

Development and use of real-time PCR to detect and quantify Mycoplasma haemocanis and "Candidatus Mycoplasma haematoparvum" in dogs

Two canine haemoplasma species have been recognised to date; Mycoplasma haemocanis (Mhc), which has been associated with anaemia in splenectomised or immunocompromised dogs, and “Candidatus Mycoplasma haematoparvum” (CMhp), recently described in an anaemic splenectomised dog undergoing chemotherapy. The study aim was to develop quantitative real-time PCR assays (qPCRs) incorporating an endogenous internal control to detect Mhc and CMhp and to apply these assays to DNA samples extracted from canine blood collected in Northern Tanzania (n = 100) and from dogs presented to a Trinidadian veterinary hospital (n = 185).

QPCRs specific for Mhc and CMhp were designed using 16S rRNA gene sequence data, and each was duplexed with an assay specific for canine glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The assays detected ≤10 copies of a sequence-specific haemoplasma plasmid per reaction and neither assay showed cross-reactivity with 10⁶ copies of the sequence-specific plasmid from the non-target canine haemoplasma species.

Nineteen of the 100 Tanzanian samples (19%) were positive for Mhc alone and one (1%) was dually infected. One Trinidadian sample was negative for canine GAPDH DNA and was excluded from the study. Of the 184 remaining Trinidadian samples, nine (4.9%) were positive for Mhc alone, five (2.7%) for CMhp alone, and two (1.1%) dually infected.

This is the first report of canine haemoplasma qPCR assays that use an internal control to confirm the presence of amplifiable sample DNA, and their application to prevalence studies. Mhc was the most commonly detected canine haemoplasma species.

Retrospective study of fever in dogs: laboratory testing, diagnoses and influence of prior treatment

OBJECTIVES

To analyse the demographic information of dogs referred for investigation of fever, to determine the usefulness of various diagnostic investigations and to assess the effect of treatment before referral on the presence of fever at referral, the duration of the investigation and the ability to reach a final diagnosis.

METHODS

The clinical records of 66 dogs, in which fever was part of the clinical signs documented by the referring veterinary surgeon, were reviewed. The effects of treatment 24 hours before referral on temperature at initial consultation and on time to diagnosis were evaluated. The effect of body temperature at initial consultation on cost and on time to diagnosis was also determined. The effect of insurance on costs incurred was assessed. The utility of different diagnostic investigations was recorded, and cases were classified according to the final diagnosis.

RESULTS

Only 34.8 per cent of dogs were diagnosed with immune-mediated disease, with most frequent diagnoses being steroid-responsive meningitis and polyarthritis. Treatment 24 hours before referral significantly increased the time to diagnosis (P = 0.004) and affected the presence of fever at referral (P = 0.006). Insurance status did not significantly affect cost incurred by the owner.

CLINICAL SIGNIFICANCE

This study documents a high incidence of immune-mediated disease in dogs referred for investigation of fever. It also documents a higher incidence of inflammatory central nervous system disease in febrile dogs than that reported previously. Of the diagnostic modalities employed in the majority of cases, radiography, cytology and bacteriological and fungal cultures (fluids/tissues) were the most useful. It is suggested that treatment is withdrawn or withheld before commencing diagnostic investigation of fever.

Measurement of cytokine mRNA expression in intestinal biopsies of cats with inflammatory enteropathy using quantitative real-time RT-PCR

Inflammatory bowel disease (IBD) is a common condition in cats characterised by infiltration of inflammatory cells into the intestinal mucosa. In this study, real-time reverse transcriptase polymerase chain reaction (RT-PCR) was used to quantify cytokine messenger RNA (mRNA) expression in intestinal biopsies from cats. Biopsies were collected from seven cats with chronic diarrhoea and histologically confirmed IBD, five cats with chronic diarrhoea due to non-IBD gastrointestinal (GI) disease, and nine clinically normal cats with or without subclinical inflammatory changes in small intestine. Real-time RT-PCR was developed for quantification of mRNA encoding interleukin (IL)-2, IL-4, IL-5, IL-6, IL-10, IL-12 (p35 and p40), IL-18, tumour necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma) and transforming growth factor-beta (TGF-beta). Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used as a 'housekeeper' gene. All real-time PCR efficiencies were>90% (range 90.4-102%) with correlation coefficients >0.99 (range 0.998-1). The results of the study were analyzed on the basis of either clinical presentation or histopathological evidence of intestinal inflammation. The former analysis showed that mRNA encoding IL-10 and TGF-beta (immunoregulatory cytokines), and IL-6, IL-18, TNF-alpha and IL-12 p40 (Th1 and pro-inflammatory cytokines) was significantly higher in clinically normal cats and cats with IBD when compared to cats with other GI diseases. IL-5 mRNA was significantly higher in cats with IBD compared to clinically normal cats. IL-2 mRNA was significantly lower in cats with non-IBD GI disease than in clinically normal cats. Analysis on the basis of histopathological change revealed that cats with intestinal inflammation had significantly more transcription of genes encoding IL-6, IL-10, IL-12p40, TNF-alpha and TGF-beta than those with normal intestinal morphology. The results suggest that immune dysregulation plays a role in feline IBD and that IBD in cats has a complicated pathogenesis with both pro-inflammatory and immunoregulatory features.

Preliminary study using an indirect ELISA for the detection of serum antibodies to Alternaria in domestic cats

Alternaria is a saprophytic fungus that is widespread in the environment; it is an opportunistic pathogen and causes disease in human beings and domestic animals. Fungal spores gain entry to the host through skin lesions and cause slow-growing, soft to firm, subcutaneous swellings, either with or without ulcers. An indirect ELISA was developed for the detection of anti-Alternaria immunoglobulin G (IgG) antibodies in serum to determine the prevalence of Alternaria exposure in domestic cats. Fifty-two of 63 cats had detectable levels of anti-Alternaria IgG antibody. There were no correlations between the concentration of antibody and the sex, breed or living environment of the cats, but cats less than two years of age had significantly lower concentrations than older cats. The cats with disease caused by culture-confirmed Alternaria infections did not have significantly higher concentrations of antibody than the healthy cats or cats with other diseases.

Diagnosis of feline haemoplasma infection in Australian cats using a real-time PCR assay

A total of 147 cats from the Sydney area of Australia that had blood samples submitted to veterinary laboratories were tested using a real-time polymerase chain reaction (PCR) assay able to detect and distinguish the two feline haemoplasma species. This sample number included two cats diagnosed with feline haemoplasma infection by routine blood smear examination. Statistical analysis was performed to evaluate associations between haemoplasma infection, age, sex, breed, haematocrit (HCT) values and anaemia status. One hundred and six cats (72.1%) were negative. Thirty-four cats (23.1%) were positive for 'Candidatus M. haemominutum', six cats (4.1%) were positive for M. haemofelis and one cat (0.7%) was positive for both species. Older, male, non-pedigree cats, with lower HCT values were more likely to be infected with 'Candidatus M. haemominutum'. Significant inverse correlation was found between the amount of M. haemofelis DNA present in the blood and the HCT value. This report documents the existence of, and prevalence of, both haemoplasma species in a sample of cats in Australia and is the first to use quantitative real-time PCR in a prevalence study for haemoplasma infection.

Diagnosis of feline haemoplasma infection using a real-time PCR assay

Haemobartonella felis has been reclassified within the genus Mycoplasma as Mycoplasma haemofelis and 'Candidatus Mycoplasma haemominutum', collectively referred to as the feline haemoplasmas. A total of 78 cats from the Johannesburg area that had blood samples submitted to a private veterinary laboratory were tested using a real-time polymerase chain reaction (PCR) assay able to detect and distinguish the two feline haemoplasma (basonym Haemobartonella) species. All samples had been diagnosed with haemoplasma infection by cytological examination of blood smears. Statistical analysis was performed to evaluate associations between haemoplasma status, age, and haematological and biochemical parameters. On PCR assay 43 cats (55%) were haemoplasma negative, 25 (32.1%) positive for 'Candidatus Mycoplasma haemominutum', 5 (6.4%) positive for Mycoplasma haemofelis and 5 (6.4%) positive for both species. Significant inverse correlation was found between the amount of M. haemofelis DNA present in the blood and the haematocrit value. Cats that were positive for M. haemofelis showed macrocytic regenerative anaemia, monocytosis and thrombocytopaenia. This report documents the existence of both haemoplasma species in cats in South Africa.

Investigation of nasal disease in the cat--a retrospective study of 77 cases

A retrospective study was undertaken to determine the prevalence of different diseases in cats referred for investigation of chronic nasal disease, to identify historical, clinical and diagnostic features which may assist in making a diagnosis, and to provide information pertaining to outcome in these cats. Diagnoses included neoplasia (30 cases), chronic rhinitis (27), foreign body (8), nasopharyngeal stenosis (5), Actinomyces infection (2), nasal polyps (2), stenotic nares (2), and rhinitis subsequent to trauma (1). The most common neoplasia was lymphosarcoma (21 cases), with a median survival of 98 days for cats treated with multiagent chemotherapy. Cats with neoplasia were older on average than the other cats, and were more likely to be dyspnoeic and have a haemorrhagic and/or unilateral nasal discharge than cats with chronic rhinitis. Cats with neoplasia were more likely to have radiographic evidence of nasal turbinate destruction, septal changes, or severe increases in soft tissue density than cats with chronic rhinitis. It was unusual for cats with diseases other than neoplasia to be euthanased as a result of their nasal disease.

Pathogen carriage by the cat flea Ctenocephalides felis (Bouché) in the United Kingdom

The carriage of Bartonella, Rickettsia felis and haemoplasma species was investigated in cat fleas (Ctenocephalides felis) collected from 121 cats and dogs in the United Kingdom. DNA extracted from fleas was analysed using genus and species-specific PCR and amplicons were characterised using DNA sequencing. Fifty percent of flea samples were PCR positive for at least one pathogen. Twenty one percent were positive for R. felis, 17% for Bartonella henselae, 40% for haemoplasma species and 20% were infected with more than one of the pathogen species studied. It is clear from the results in this study that companion cats and dogs are commonly infested with Ct. felis carrying bacterial pathogens of significance to human and animal health. These findings raise the possibility that Ct. felis found on dogs and cats are a potential source of infection with such pathogens for humans.

Phylogenetic analysis of hemoplasma species: an international study

Nearly complete 16S rRNA gene sequences for feline and canine hemoplasma isolates from Europe, Australia, Africa, and Asia showed almost 100% identity to those previously reported for United States isolates. Partial sequences of the RNA subunit of the RNase P gene were also determined, and RNase P-based phylogenetic analysis showed that the hemoplasmas are most closely related to the members of the Mycoplasma pneumoniae group.

Use of a PCR assay to assess the prevalence and risk factors for Mycoplasma haemofelis and 'Candidatus Mycoplasma haemominutum' in cats in the United Kingdom

Blood samples from 426 healthy and sick cats in the UK were tested in a PCR assay for 'Candidatus Mycoplasma haemominutum' and Mycoplasma haemofelis (basonym Haemobartonella felis). Seventy-two of the cats (16.9 per cent) were positive for 'Candidatus M. haemominutum' alone, six (1.4 per cent) were positive for M. haemofelis alone and one (0.2 per cent) was positive for both. Logistic regression analysis indicated that older male cats were significantly more likely to be infected with 'Candidatus M. haemominutum', but there was no significant association between it and any of the haematological variables measured. M. haemofelis infection was uncommon in the anaemic cats sampled, and there were too few positive cases for multivariable analysis to be performed for M. haemofelis-positive status.

Haemobartonella felis: recent developments in diagnosis and treatment

Haemobartonella felis is a pleomorphic uncultivated wall-less haemotrophic bacterial parasite. Phylogenetic analysis of 16S rRNA gene sequences from a number of isolates of H felis has demonstrated that these bacteria are most closely related to species in the genus Mycoplasma, and Haemobartonella and related organisms are currently being reclassified as Mollicutes. Diagnosis by cytological examination of blood smears has been problematic, but recent molecular studies have led to the development of sensitive polymerase chain reaction (PCR) assays for diagnosis. Such studies have also resulted in the recognition of two distinct strains of H felis, which are divided into different groups based on phylogenetic analysis. This evolutionary divergence between strains is accompanied by differences in pathogenecity. This review discusses new developments in the diagnosis and treatment of H felis, focusing on the use of, and interpretation of, PCR assays.

16S rDNA comparison demonstrates near identity between an United Kingdom Haemobartonella felis strain and the American California strain

A handful of North American (USA) strains of the uncultured erythrocytotrophic pathogen of cats, Haemobartonella felis, have been differentiated by comparison of the 16S rRNA gene sequences. Using this approach, an UK strain was characterised, providing an identity for a non-USA H. felis for the first time. This strain shared close phylogenetic homology with the USA Californian strain.

Evaluation of methods of platelet counting in the cat

Platelet counts were performed in 50 cats presented for diagnostic investigation. For each cat, counts were obtained using a manual haemocytometer method and compared with counts obtained by estimation from a stained blood smear, a QBC VetAutoread analyser, a Zynocyte VS/2000 analyser, impedance automated counts on a Baker System using both EDTA and citrated anticoagulated blood, and use of a Zynostain modified counting chamber kit. None of the methods gave high correlation with the haemocytometer counts. The blood smear estimation of platelet counts had the highest correlation (r = 0.776) and was the only method to have reasonable values for both sensitivity and specificity. With the impedance automated counts, citrated anticoagulated blood had marginally higher correlation than EDTA anticoagulated blood, and the time between blood sampling and platelet count determination had no effect on the count obtained. When in-house analyser or impedance automated platelet counts are abnormal or not consistent with clinical findings, the authors recommend that a manual platelet count using either haemocytometry or examination of a blood smear is performed.

Use of real-time quantitative PCR to detect Chlamydophila felis infection

A real-time PCR assay was developed to detect and quantify Chlamydophila felis infection of cats. The assay uses a molecular beacon to specifically identify the major outer membrane protein gene, is highly reproducible, and is able to detect fewer than 10 genomic copies.

Hypoadrenocorticism in a cat

Primary hypoadrenocorticism was diagnosed in an eight-year-old neutered male cat. The predominant presenting complaint was dysphagia. Other historical signs included lethargy, weight loss, polydipsia, polyuria, muscle weakness and occasional vomiting. The signs had waxed and waned over the two months before presentation and had improved when the cat was treated with enrofloxacin and prednisolone by the referring veterinarian. On referral, dehydration, depression and poor bodily condition were found on physical examination. Results of initial laboratory tests revealed mild anaemia, hyperkalaemia, hyponatraemia, hypochloraemia and elevations in serum creatinine and creatine kinase. The diagnosis of primary adrenocortical insufficiency was established on the basis of results of an adrenocorticotropic hormone (ACTH) stimulation test and endogenous plasma ACTH determination. Initial therapy for hypoadrenocorticism included intravenous administration of 0.9 per cent saline and dexamethasone, and oral fludrocortisone acetate. Within one week the cat was clinically normal and two years later was still alive and well on fludrocortisone acetate treatment only.

Spontaneous laryngeal paralysis in four white-coated German shepherd dogs

Four cases of spontaneous laryngeal paralysis in juvenile white-coated German shepherd dogs are described. The presenting signs were typical for laryngeal paralysis, with stridor present in all four cases. Laryngoscopy revealed bilateral laryngeal paralysis in three cases, and unilateral paralysis in one. Concurrent megaoesophagus was also identified in one dog. All dogs underwent surgical treatment for laryngeal paralysis. Euthanasia was performed in one case due to intractable regurgitation and aspiration pneumonia. A possible association with white coat colour is discussed.

Preliminary clinical observations on the use of piroxicam in the management of rectal tubulopapillary polyps

Rectal tubulopapillary polyps were diagnosed in eight dogs following proctoscopy and mucosal pinch biopsy. Histological examination of the pinch biopsies revealed evidence of malignant transformation in three of the cases. The remaining cases were diagnosed as benign polyps. Inflammatory changes were observed in four cases. Seven dogs were treated with piroxicam suppositories and one with oral piroxicam. All dogs were re-examined after four to six weeks of piroxicam therapy and the extent of haematochezia, tenesmus and faecal mucus production was reduced in all cases. The owners of seven of the dogs considered the improvement in clinical signs to be good or excellent. Cases with and without evidence of inflammation responded equally well. This finding supports the hypothesis that piroxicam has an antineoplastic effect due to apoptosis and alteration in the cell cycle. Medical management with piroxicam may provide a non-invasive treatment option for dogs with rectal polyp formation in which surgical treatment is likely to be associated with complications such as incontinence, infection and wound breakdown, or where the owner declines such treatment.

Idiopathic phenobarbital-responsive hypersialosis in the dog: an unusual form of limbic epilepsy?

Three unusual cases of salivary gland enlargement and hypersialosis in the dog that responded to anticonvulsant therapy are reported. Presenting complaints included weight loss, hypersalivation, retching and vomiting of several weeks' duration. Two dogs were presented with enlarged painful mandibular salivary glands. The third dog exhibited bizarre behaviour (including jaw chattering) and developed enlarged painful mandibular salivary glands during hospitalisation. Fine needle aspirate cytology and biopsies from the enlarged salivary glands revealed no significant pathological changes. In one dog, an electroencephalogram revealed changes consistent with epilepsy. Hypersialism and salivary gland enlargement resolved completely during phenobarbital administration in all cases. Two dogs were successfully weaned off treatment six months after diagnosis. The remaining dog relapsed after eight months, but normalised with the addition of oral potassium bromide. It is hypothesised that the syndrome idiopathic hypersialosis may in fact be an unusual form of limbic epilepsy.

Comparison of PCR detection methods for B1, P30, and 18S rDNA genes of T. gondii in aqueous humor

PURPOSE

Comparison of polymerase chain reaction (PCR) amplification of three Toxoplasma gondii genes in aqueous humor.

METHODS

Nested PCRs carried out using published methods were optimized for maximum sensitivity and specificity. Five pairs of oligonucleotide primers, directed against the B1, P30, and ribosomal genes, were used and compared to determine which sequences were most effective in detecting T. gondii DNA. Methods were developed with DNA templates in water and were subsequently applied to both normal and inflamed aqueous.

RESULTS

After one round of PCR amplification, P30 and ribosomal primers were able to detect 1 pg genomic T. gondii DNA. However, those directed against the B1 gene were able to detect 50 fg (approximately single tachyzoite). This level of sensitivity was also achieved using the P30 primers after a second round of PCR; however, only primers based on the B1 gene maintained this level of sensitivity in both normal and inflamed aqueous. B1-specific primers did not amplify sequences from fungal, bacterial, or human lymphocyte DNA. The sensitivity of T. gondii detection using B1 gene-specific primers was not compromised when large amounts of human lymphocyte DNA were present, and application to an ocular sample or retinal section from patients with toxoplasma chorioretinitis was successful in confirming the presence of T. gondii DNA.

CONCLUSIONS

The B1 PCR protocol appears to be the most sensitive protocol in the detection of T. gondii DNA and has been successful in identification of T. gondii DNA in ocular fluids and retinal sections. This provides direct evidence of the presence of T. gondii within the eye and may therefore help in the management of toxoplasma retinochoroiditis.

Use of a mucosal advancement flap for the treatment of nasopharyngeal stenosis in a cat

A three-and-a-half-year-old male neutered domestic short-haired cat was presented with a three-year history of stertor and intermittent open-mouth breathing. No airflow was detected from either nostril when checked using a cold slide test. Oropharyngeal swabs were positive for calicivirus, while skull radiographs were suggestive of a dorsal deviation of the soft palate. The diagnosis of nasopharyngeal stenosis was confirmed via cannulation of the nasal passages and direct examination of the oropharynx under general anaesthesia. A midline approach through the soft palate was used to excise the adhesions. The resulting defect was reconstructed by advancement of a mucosal flap elevated from the dorsal nasopharynx and laryngopharynx. The cat was free of clinical signs 28 months later.

Meningococcal pneumonia: characterization and review of cases seen over the past 25 years

Fifty-eight cases of meningococcal pneumonia were included in this review. Fifty cases previously described in the literature from 1974 through 1998 and 8 new cases were included in this series. The median age of patients was 57.5 years, and pleuritic chest pain was described in 21 (53.9%) of 39 cases. Blood cultures were positive in 42 (79.3%) of 53 cases for which results were mentioned. Despite the presence of bacteremia, patients did not develop the syndrome of meningococcemia with its associated complications. Serogroup Y meningococci were most commonly recovered and accounted for 44.2% of identified isolates. Therapy has dramatically changed over the past 25 years; prior to 1991, penicillin antibiotics were most often used. Since 1991, 12 (80%) of 15 patients received cephalosporin antibiotics. Only 5 (8.62%) of 58 patients died. Secondary cases of meningococcal infections following exposure to patients with meningococcal pneumonia were noted in 2 instances.

A case of feline primary hypoadrenocorticism

A 2-year-old entire female British Shorthair cat was referred to the University of Bristol for investigation of lethargy, weakness, constipation and hypothermia. Clinical examination revealed a profoundly weak, hypovolaemic and hypothermic cat. Serum biochemistry revealed hyponatraemia, hyperkalaemia and hyperphosphataemia and the urine was isosthenuric. Lack of response to exogenous adrenocorticotrophic hormone confirmed a diagnosis of hypoadrenocorticism. Treatment consisted initially of intravenous fluid therapy and subsequently a combination of fludrocortisone and prednisolone per os. At follow-up, 20 months after the initial diagnosis the cat remained stable and free of clinical signs.