Single-tube nested PCR for detection of tritrichomonas foetus in feline feces

Comparison Study of Four Extraction Methods Combined with PCR and LAMP for Feline Tritrichomonas foetus Detection in Fecal Samples

Feline trichomonosis occurs worldwide, with gastrointestinal symptoms such as chronic large-bowel diarrhea and abdominal pain. The inclusion of molecular methods in diagnostic and epidemiological studies has necessitated an effective method for extracting DNA from feces. We tested four extraction commercial kits: ZR Fecal DNA MiniPrep (50 preps) (Zymo Research, Irvine, CA, USA), QIAamp^® DNA Stool Mini Kit (Qiagen Inc., Valencia, CA, USA), UltraClean Fecal DNA Kit (50 preps) (MO BIO, San Diego, CA, USA), and Sherlock AX/100 isolations (A&A Biotechnology, Gdynia, Poland). We assessed the sensitivity of detection of Tritrichomonas foetus in spiked fecal samples for the four kits combined with two molecular assays: PCR and LAMP. The extraction efficacy was quantified using defined aliquots of fecal samples spiked with 5 μL of suspensions containing serial dilutions of trophozoites (0.1; 1; 10; 100; 1000; 10,000), with six replicates for each concentration. In our study, we proved that the ZR Fecal DNA MiniPrep (50 preps) kit combined with LAMP and PCR had the highest efficiency among all the compared methods for the detection of feline T. foetus from fecal samples.

Molecular detection of Tritrichomonas foetus in bovine samples: a novel real-time polymerase chain reaction (PCR) assay targeting EF1-alpha-Tf1 and a comparative study of published PCR techniques

The parasite T. foetus causes trichomonosis in cattle but is generally asymptomatic in males. Thus, many bulls carrying the disease go unnoticed, making the detection of T. foetus in bulls an important aspect for its control. Due to drawbacks posed by its cultivation, PCR is a preferred option for diagnostic laboratories. Most published PCR protocols target the genomic region compring the 18S, 5.8S, and 28S rRNA genes and internal transcribed spacers 1 and 2 (rRNA-ITS region), homologous to that of other Tritrichomonas species. There is minimal information on alternative genetic targets and no comparative studies have been published. We compared a protocol based on the microsatellite TfRE (called H94) and five protocols based on the rRNA-ITS region (called M06, M15, G02, G05, and N02). We also designed and evaluated a novel PCR-based assay on the EF1-alpha-Tf1 gene (called V21). The analytical sensitivity and specificity assays for the PCR protocols were performed according to the World Organisation for Animal Health (OIE) directives and the comparative study was performed with a widely used PCR (M06) on clinical samples from 466 breeding bulls. V21 showed a high degree of agreement with our reference M06 (kappa = 0.967), as well as M15 (kappa = 0.958), G05 (kappa = 0.948), and H94 (kappa = 0.986). Protocols H94 and V21 appear to be good approaches for confirming clinical cases in preputial bull samples when genomic regions alternative to rRNA-ITS are required. By contrast, N02 gave false negatives and G02 false positives.

The first report of clinical case of intestinal trichomoniasis caused by Tritrichomonas foetus in a cat with chronic diarrhea in Iran

Background

Tritrichomonas foetus is recently found to be one of the causes of chronic diarrhea in domestic cats but there is no report of feline intestinal trichomoniasis in Iran.

Case description

A 9 months female domestic short-haired cat was referred to our hospital with a history of chronic diarrhea over the past two months, and with an unsuccessful previous antibiotic therapy in another clinic.

Findings/treatment and outcome

Clinical examination revealed 39.8°C rectal temperature. Complete blood count (CBC) showed moderate inflammatory leukogram. By the wet-mount faecal assessment, moving organisms were observed. Rectal scarping dry-mount cytology revealed many inflammatory cells along with huge numbers of trophozoites with typical morphologic characteristics including central axostyle, undulating membrane, flagella, and one laterally located nucleus. Polymerase chain reaction (PCR) was performed and confirmed the diagnosis of T. foetus. After treatment with metronidazole and probiotics, the cat was completely recovered.

Conclusion

This study represents the first case of intestinal trichomoniasis in a cat with chronic diarrhea in Iran.

Tritrichomonas foetus in cats from Central Italy: Clinical signs and risk factors

Tritrichomonas foetus (Trichomonadida, Tritrichomonadidae) is a parasitic protozoan which causes a diarrheic disease in domestic cats worldwide. The epizootiological and pathogenic impact of this parasite in many geographic locations is still to be unraveled; thus, the present study has investigated the occurrence of T. foetus in cats from central Italy, along with the analysis of risk factors and clinical signs. One hundred and five cats referred to the University Veterinary Teaching Hospital of the University of Teramo were tested with copromicroscopic techniques for common intestinal and extra-intestinal parasites and a specific PCR for T. foetus. A statistical analysis evaluating associations between T. foetus positivity and possible risk factors was performed. One animal scored positive for Giardia (0.95%), 2 for Toxocara cati (1.90%), 1 for Eucoleus aerophilus (syn. Capillaria aerophila) (0.95%), 9 for Aelurostrongylus abstrusus (8.57%) and 1 for Dipylididum caninum (0.95%), while T. foetus was molecularly recorded in 18/105 (17.14%) of the study cats. In two cats, T. foetus was found in association respectively with Giardia and A. abstrusus. Animals with chronic gastrointestinal signs were more significantly infected by T. foetus (40.90% vs 10.84%; p < 0.01; 95% CI = 1.90-17.04; OR = 5.69) in comparison to cats with no gastrointestinal distresses. No other statistically significant associations were found. This study confirms that T. foetus is enzootic in cats in Italy and that it should be included in the differential diagnosis of feline chronic gastrointestinal diseases.

Dysbiosis of fecal microbiota in cats with naturally occurring and experimentally induced Tritrichomonas foetus infection

The protozoal pathogen Tritrichomonas foetus infects the colon of domestic cats and is a major cause of chronic colitis and diarrhea. Treatment failure is common, but antibiotics may improve clinical signs in a subset of cats, leading researchers to question involvement of the colonic microbiota in disease pathogenesis. Studies performed in women with venereal Trichomonas vaginalis infections have revealed that dysbiosis of host microbiota contributes to pathogenicity with similar findings also found in mice with intestinal Tritrichomonas musculis The aim of this study was to characterize differences in the fecal microbiota of cats with and without naturally occurring T. foetus infection and in a group of kittens prior to and after experimentally induced infection. Archived fecal DNA from cats undergoing testing for T. foetus infection (n = 89) and experimentally infected kittens (n = 4; at pre-, 2 weeks, and 9 weeks post-infection) were analyzed by sequencing of 16S rRNA genes. Amongst the naturally infected population, the genera Megamonas and Helicobacter were significantly increased in prevalence and abundance in cats testing positive for T. foetus infection. In the group of four experimentally infected kittens, fecal samples post-infection had significantly lower abundance of genus Dialister and Megamonas and greater abundance of the class Betaproteobacteria and family Succinivibrionaceae. We hypothesize that T. foetus promotes dysbiosis by competition for fermentable substrates used by these bacteria and that metabolic byproducts may contribute to the pathogenesis of colonic inflammation and diarrhea. Future studies are warranted for the measurement of fecal concentrations of microbial and protozoal metabolites in cats with T. foetus infection for the identification of potential therapeutic targets.

Prevalence of Tritrichomonas foetus infection in cats in Bangkok metropolitan area and in vitro drug sensitivity testing

Tritrichomonas foetus is a causative agent of feline trichomonosis, resulting in large-bowel diarrhea in cats. Feline trichomonosis has been reported in the USA, Europe and some Asian countries but there is limited information for Thailand. This study investigated the prevalence of T. foetus infection in cats in the Bangkok metropolitan area and evaluated the in vitro efficacy of metronidazole (MDZ) and ronidazole (RDZ) against T. foetus Thai isolates. In total, 215 fecal samples were collected from 121 owned cats and 94 stray cats. All fecal samples were cultivated in InPouch™ TF-feline medium. Afterward, polymerase chain reaction (PCR) assays targeting the 5.8S rRNA gene, the ITS regions and DNA sequencing were used for the confirmation of T. foetus. The overall prevalence of T. foetus infection was 4.18% (9/215) based on cultivation and PCR. The sequencing results showed 100% homology to T. foetus sequences from GenBank. The average minimal lethal concentrations (MLCs) of MDZ were 333.33 and 66.67 μg/ml at 24 and 48 h, respectively. The average MLCs of RDZ were 29.16 and 12.5 μg/ml at 24 and 48 h, respectively. The MLC of the MDZ results revealed that T. foetus Thai isolates had a tendency to be MDZ-resistant. To the best of the authors' knowledge, this study was the first using in vitro cultivation and molecular techniques to report and confirm the presence of T. foetus in cats living in the Bangkok metropolitan area. Further studies are needed to determine the genuine infection rate of T. foetus in a greater population sample and the infection status in cats with signs of diarrhea in Thailand.

Association of fecal sample collection technique and treatment history with Tritrichomonas foetus polymerase chain reaction test results in 1717 cats

BACKGROUND

Fecal polymerase chain reaction (PCR) testing for Tritrichomonas foetus is considered the most sensitive means for diagnosis of infection but results could be influenced by fecal collection technique and prior use of antimicrobial drugs.

OBJECTIVES

To establish any association between fecal collection technique or treatment history and results of fecal PCR testing for T. foetus.

ANIMALS

Fecal samples from 1717 cats submitted by veterinarians between January 2012 and December 2017.

METHODS

This study used a retrospective analysis. T. foetus PCR test results from 1808 fecal samples submitted for diagnostic testing were examined for their association with method of fecal collection and prior antimicrobial treatments. Data were collected from sample submission form.

RESULTS

Positive T. foetus PCR test results were obtained for 274 (16%) cats. Fecal samples collected via fecal loop had increased probability of positive PCR test results (odds ratio [OR] 2.04, 95% confidence interval [CI] 1.31-3.17, P = .002) compared to samples collected by colonic flush. There was no association between PCR test results and treatment history, treatment type, or prior treatment with ronidazole. After an initial positive PCR test, 4/19 (21%; 95% CI 2.7%-39.4%) cats treated with ronidazole had a second positive test result.

CONCLUSIONS AND CLINICAL IMPORTANCE

Results of this study support that fecal samples collected by loop might be better for PCR diagnosis of T. foetus infection. Lack of association of ronidazole with PCR test results and a 21% all-potential-causes failure rate of ronidazole in cats with preconfirmed infection are important limitations to use of this drug.

Tritrichomonas Foetus as a Causative Agent of Tritrichomonosis in Different Animal Hosts

Tritrichomonas foetus is a protozoan parasite that has been traditionally identified as a cause of reproductive tract disease in cattle and gastrointestinal tract infection in cats. Moreover, T. foetus is also well known as a commensal of the nasal cavity, intestines, and stomach in swine. In this review we describe T. foetus as a pathogen dangerous to more than one animal host, diagnostic and taxonomic aspects of this infection, and the extent to which isolates from different hosts share genetic identity.

Efficacy and safety of ronidazole treatment against Tritrichomonas foetus in a cat colony with multiple disorders

In a group of pedigree cats (n = 17) in poor health condition housed in an animal shelter in Vienna, Austria, with a history of persistent diarrhea, Tritrichomonas foetus infection was detected by PCR. Despite pre-existing clinical conditions all cats were treated with ronidazole (30 mg/kg PO q24h for 14 days) under close observation. After treatment, 11 of 14 initially positive animals remained negative for T. foetus during the observation period (six to eight weeks post treatment) and no diarrhea was observed. During treatment, nine cats showed mild to moderate neurological disorders (incoordination, mild tremor) at least once; six of these had already shown similar signs before treatment. Ronidazole treatment of multimorbid animals is acceptable if the benefit (here: clinical resolution and release from quarantine for adoption) is high. It is hypothesized that a high degree of inbreeding is a significant risk factor for the development of tritrichomonosis in cats.

What is known about Tritrichomonas foetus infection in cats?

Tritrichomonas foetus is a parasite that has been definitively identified as an agent of trichomonosis, a disease characterized by chronic diarrhea. T. foetus colonizes portions of the feline large intestine, and manifests as chronic and recurrent diarrhea with mucus and fresh blood, which is often unresponsive to common drugs. Diagnosis of a trichomonad infection is made by either the demonstration of the trophozoite on a direct fecal smear, fecal culture and subsequent microscopic examination of the parasite, or extraction of DNA in feces and amplification by the use of molecular tools. T. foetus is commonly misidentified as other flagellate protozoa such as Giardia duodenalis and Pentatrichomonas hominis. Without proper treatment, the diarrhea may resolve spontaneously in months to years, but cats can remain carriers of the parasite. This paper intends to serve as a source of information for investigators and veterinarians, reviewing the most important aspects of feline trichomonosis, such as trichomonad history, biology, clinical manifestations, pathogenesis, world distribution, risk factors, diagnosis, and treatment.

Pentatrichomonas hominis infection in two domestic cats with chronic diarrhea

Case series summary

Chronic diarrhea is a common and recurring problem in feline medicine. Intestinal trichomonads have been reported as causative agents of diarrhea in cats. While Pentatrichomonas hominis is considered commensal, Tritrichomonas foetus has been found to cause feline large bowel diarrhea in cats. In our report, two young cats infected with the feline leukemia virus (FeLV) and presenting with chronic diarrhea were identified as having trichomonads in their feces, based on direct examination and fecal culture. Molecular assays (PCR and DNA sequencing) revealed that the parasite involved was P hominis, not T foetus, as was suspected. The animals had already been subjected to ineffective therapy with metronidazole, and after the use of ronidazole, their feces became dry and formed.

Relevance and novel information

This case report describes P hominis infection as a possible cause of chronic diarrhea in two young cats also infected by FeLV. The parasite was probably resistant to metronidazole, the drug of choice in the literature, and sensitive to ronidazole. Although considered commensal, P hominis infection should be evaluated as a differential diagnosis in cats with chronic diarrhea, especially those that are immunocompromised. Moreover, a combination of techniques such as direct examination and/or fecal culture and PCR is essential for an accurate diagnosis of P hominis infection.

Tritrichomonas foetus and Mycoplasma felis coinfection in the upper respiratory tract of a cat with chronic purulent nasal discharge

A 5-year-old indoor male neutered Siamese cat was presented with clinical signs of sneezing and chronic bilateral purulent nasal discharge. Multiple nasal cavity swabs were submitted for bacterial cultures, Mycoplasma felis-DNA qPCR, and cytology. M felisqPCR was positive and cytomorphologic diagnosis was severe, acute, purulent, rhinitis with intralesional protozoal microorganisms consistent with a Trichomonas spp. Nested PCR (nPCR) confirmed the diagnosis of Tritrichomonas foetus. Systemic therapy with doxycycline for M felis and metronidazole for T foetus was started with remission of clinical signs within 2 weeks; however, symptoms relapsed shortly after therapy was discontinued. This study represents the first documented case of T foetus associated with chronic nasal discharge in a cat, which supports the hypothesis that T foetus can live in the nasal cavity. It is also the first reported case of M felis and T foetus coinfection, which indicates that with mycoplasmal feline upper respiratory tract infections, T foetus should be considered as a coinfecting agent.

Detection of natural occurrence of Tritrichomonas foetus in cats in Araçatuba, São Paulo, Brazil

ABSTRACT: The aim of this study was to investigate the occurrence of Tritrichomonas foetus in cats in the area surrounding the city of Araçatuba municipality, State of São Paulo, Brazil. Fecal samples from 129 cats were collected by rectal flush technique. It was compared two diagnosis methods, direct examination of feces and PCR. The presence of T. foetus DNA was verified using PCR by amplification of 347-bp fragment from the primers TFR3 and TFR4 and amplicons of positive cases were sequenced. Statistical analyses were performed investigating the associations between T. foetus infection with gender, age, breed, presence of diarrhea and/or history of diarrhea, previous treatment, lifestyle, origin, environment, and co-infection. T. foetus was observed in one sample (n=129) by direct microscopic examination of feces while PCR was positive in five samples (3.9%). Giardia species and Cryptosporidium species co-infection was also observed. Statistical analyses showed no significant associations between T. foetus infection and all listed factors, although most positive cats were asymptomatic and lived in multi-cat household. The isolates of T. foetus showed 100% identical sequences with other T. foetus isolates from cats around the world. So, the occurrence of T. foetus was confirmed in cats in Araçatuba city (Brazil). This parasite must be considered as a differential diagnosis in cats with diarrhea and also in asymptomatic carriers as source of infection in multi-cat environments.

Trichomonas

The most widely known trichomonad in veterinary medicine is Tritrichomonas foetus. It is the etiologic agent of bovine tritrichomonosis, a sexually transmitted disease in extensively managed herds throughout many geographic regions worldwide. The same trichomonad species is also regarded as the causative agent of chronic diarrhea in the domestic cat, although more recent studies observed molecular differences between bovine- and feline-derived T. foetus. Trichomonosis in cats has a worldwide distribution and is mainly present among cats from high-density housing environments. Other trichomonads are found as inhabitants of the gastrointestinal tract in birds, such as Trichomonas gallinae. Particularly, Columbiformes, Falconiformes, Strigiformes, and wild Passeriformes can be severely affected by avian trichomonads. Diagnosis of trichomonosis is often complicated by the fragility of the parasite. To ensure valid test results, it is essential to collect and handle specimens in the right way prior to analysis. Cultivation tests, the specific amplification of parasites, or a combination of both test methods is the most efficient and most commonly used way to diagnose trichomonosis in animals. Bovine tritrichomonosis is mainly controlled by the identification and withdrawal of infected animals from bovine herds. The control of feline and avian trichomonosis relies mainly on preventive measures.

Assessment of listing and categorisation of animal diseases within the framework of the Animal Health Law (Regulation (EU) No 2016/429): Trichomonosis

Trichomonosis has been assessed according to the criteria of the Animal Health Law (AHL), in particular criteria of Article 7 on disease profile and impacts, Article 5 on the eligibility of trichomonosis to be listed, Article 9 for the categorisation of trichomonosis according to disease prevention and control rules as in Annex IV and Article 8 on the list of animal species related to trichomonosis. The assessment has been performed following a methodology composed of information collection and compilation, expert judgement on each criterion at individual and, if no consensus was reached before, also at collective level. The output is composed of the categorical answer, and for the questions where no consensus was reached, the different supporting views are reported. Details on the methodology used for this assessment are explained in a separate opinion. According to the assessment performed, trichomonosis can be considered eligible to be listed for Union intervention as laid down in Article 5(3) of the AHL. The disease would comply with the criteria as in sections 3, 4 and 5 of Annex IV of the AHL, for the application of the disease prevention and control rules referred to in points (c), (d) and (e) of Article 9(1). The animal species to be listed for trichomonosis according to Article 8(3) criteria is cattle as susceptible and reservoir.

Evaluation of surface antigen TF1.17 in feline Tritrichomonas foetus isolates

Tritrichomonas foetus (T. foetus) is a flagellated protozoa that infects the distal ileum and proximal colon of domestic cats, as well as the urogenital tract of cattle. Feline trichomonosis is recognized as a prevalent cause of chronic diarrhea in cats worldwide. The suspected route of transmission is fecal-oral, with cats in densely crowded environments at highest risk for infection. Thus, the recommended strategy for minimizing spread of infection is to identify and isolate T. foetus-positive cats from the general population. Rapid identification of infected cats can be challenging due to the inability to accurately and quickly detect the organism in samples at point of care facilities. Thus, identification of targets for use in development of a novel diagnostic test, as well as a vaccine or therapy for T. foetus infection is a significant area of research. Despite a difference in organ tropism between T. foetus genotypes, evidence exists for conserved virulence factors between feline and bovine T. foetus. The bovine T. foetus surface antigen, TF1.17, is an adhesin that is conserved across isolates. Vaccination with the purified antigen results in amelioration of cytopathogenicity and more rapid clearance of infection in cattle. We previously showed that three feline isolates of T. foetus were positive for TF1.17 antigen so we further hypothesized that TF1.17 is conserved across feline T. foetus isolates and that this antigen would represent an attractive target for development of a novel diagnostic test or therapy for feline trichomonosis. In these studies, we used monoclonal antibodies previously generated against 1.15 and 1.17 epitopes of the bovine T. foetus TF1.17 antigen, to evaluate for the presence and role of TF1.17 in the cytopathogenicity of feline T. foetus. A previously validated in vitro co-culture approach was used to model feline T. foetus infection. Immunoblotting, immunofluorescence assays, and flow cytometric analysis confirmed the presence and surface localization of antigen TF1.17 across all feline T. foetus isolates tested. Antigen TF1.17 was notably absent in the presumably nonpathogenic intestinal trichomonad, Pentatrichomonas hominis, a parasite that can be confused microscopically with T. foetus. Similar to bovine trichomoniasis, TF1.17 was found to promote T. foetus adhesion to the intestinal epithelium. These results support further characterization and development of the TF1.17 antigen as a possible target for the diagnosis and prevention of feline T. foetus infection.

The conundrum of feline Trichomonosis

Practical relevance: Trichomonosis of the large intestine of the cat was described as a cause of chronic diarrhea over 20 years ago. The trichomonad was identified as Tritrichomonas foetus, with a genotype that is distinct from venereal T foetus of cattle. Clinical challenges: Despite multiple means for diagnosis of the infection, including light microscopy, protozoal culture and PCR amplification using species-specific primers, tests with even greater sensitivity are needed. Feline trichomonosis is resistant to all commonly used antiprotozoal drugs. Ronidazole is currently the only drug demonstrated to be effective in eliminating the infection from cats; however, this drug has a narrow safety margin and clinical resistance is increasingly recognized. The more we learn about trichomonosis in cats, the more complicated and controversial the infection has become, ranging from what we should call the organism to whether we should even bother trying to treat it. Global importance: Feline trichomonosis is recognized to occur worldwide and is regarded as one of the most common infectious causes of colitis in the domestic cat. The infection is widespread in catteries and shelters; and, while remission of diarrhea may occur over time, persistence of the infection is common. Evidence base: This review provides a comprehensive examination of what is currently known about feline trichomonosis and pinpoints areas, based on the authors' opinion, where further research is needed.

Zoonotic Trichomonas tenax and a new trichomonad species, Trichomonas brixi n. sp., from the oral cavities of dogs and cats

Trichomonads are known to inhabit the oral cavities of various mammals, including dogs, cats and horses. However, little attention has been paid to species identification, prevalence and zoonotic potential of these parasites, although their hosts live in close proximity with humans. According to the original description, oral trichomonads in dogs and cats belong to the genus Tetratrichomonas. Interestingly, later investigations suggested that the oral cavities of dogs and cats could be infected with different species of the genus Trichomonas, including the human oral cavity parasite Trichomonas tenax. Thus, in this study we investigated the occurrence of oral trichomonads in 111 domestic dogs and 122 cats using cell cultivation methods, nested PCR analyses, and the sequencing of ITS1-5.8rRNA-ITS2 regions. We found that both dogs and cats harbour T. tenax, with prevalences of 8.1% and 4.1%, respectively. Considerably more dogs were infected with different species of the genus Trichomonas (30.6%), which we also identified in cats (6.6%). An analysis of the potential risk factors suggested that dogs of more than 3years old or with dental disease signs are more frequently infected with Trichomonas sp. than younger dogs or dogs without the disease signs, and that crossbreed dogs revealed increased rates of infection in comparison with purebred dogs. An analysis of the cat population suggested that Trichomonas sp. infection is lower in younger and crossbreed cats. Although the morphology of Trichomonas sp. is very similar to that of T. tenax, based on a phylogenetic analysis of ITS1-5.8rRNA-ITS2 regions and the ssrRNA genes, we consider Trichomonas sp. to represent a new trichomonad species, for which we propose the name Trichomonas brixi.

Prevalence and Molecular Characterization of Intestinal Trichomonads in Pet Dogs in East China

The trichomonad species Tritrichomonas foetus and Pentatrichomonas hominis were recently detected in the feces of dogs with diarrhea. However, little information is available on the prevalence and pathogenicity of these parasites in the canine population. Therefore, the aim of this study was to determine the prevalence and molecular characterization of trichomonads infecting pet dogs in Anhui and Zhejiang provinces, east China. In total, 315 pet dogs, with or without diarrhea, from 7 pet hospitals were included in this epidemiological survey. Microscopy and PCR detected P. hominis in 19.7% (62/315) and 31.4% (99/315) of fecal samples, respectively. T. foetus infection was detected in 0% (0/315) of samples with microscopy and in 0.6% (2/315) with PCR. The prevalence of P. hominis was significantly higher in young dogs (≤12 months) than in adult dogs (>12 months), and was significantly higher in diarrheic dogs (50.6%) than in non-diarrheic dogs (24.3%; P<0.05). Infection with T. foetus did not correlate with any risk factors evaluated in this study. A sequence analysis of the P. hominis PCR products showed minor allelic variations between our sequences and those of P. hominis strains from other hosts in different parts of the world. Type CC1 was the most common strain in dogs in east China. The internal transcribed spacer 1 (ITS1)-5.8S rRNA gene sequences from the 2 T. foetus isolates detected in this study displayed 100% identity and were homologous to the sequences of other strains isolated from domestic cats in other countries.

Cross-sectional survey on Tritrichomonas foetus infection in Italian cats

The feline genotype of Tritrichomonas foetus is a widespread cause of large-bowel diarrhoea in cats. The aim of this study was to determine the prevalence of the T. foetus infection in cat populations across Italy. Fresh, individual faecal samples were collected from 267 cats, kept in different environments (i.e., private households, breeding structures, municipal catteries and colonies) in three different sites across Italy. The faecal samples were tested by PCR to detect T. foetus. Moreover, the same samples were subjected to a concentration-flotation technique and a commercial direct fluorescent-antibody (DFA) test to detect additional enteric parasites, including Giardia duodenalis. The overall prevalence of T. foetus infection was 5.2%. All the infected cats showed diarrhoea at the time of sampling: 9 out of 14 positive cats were co-infected with G. duodenalis, 1 with Toxocara cati and 3 with Dipylidium caninum. The risk factor analysis showed that not only the breed, but also co-infections with G. duodenalis and Dipylidium caninum were significantly associated with the presence of T. foetus. This study confirms the presence of T. foetus in cats living in Italy, suggesting that this protozoan parasite should always be included in the differential diagnosis of patients referred with large-bowel disease symptoms, especially if they were purebred animals, or affected by other enteric protozoa, such as G. duodenalis.

Treatment of feline giardiasis during an outbreak of diarrhoea in a cattery: potential effects on faecal Escherichia coli resistance patterns

OBJECTIVES

An outbreak of diarrhoea involving 16 cats at a cattery in Norway was investigated. Treatment and control of the outbreak were the primary objectives, but the effects of treatment on the antimicrobial resistance profiles of Escherichia coli isolated from faeces were also investigated.

METHODS

Faecal samples were investigated for Giardia cysts by immunofluorescence microscopy, and multi-locus genotyping was performed to determine the Giardia genotype. Faecal E coli were assessed, before and after treatment for giardiasis, for antimicrobial resistance.

RESULTS

The outbreak was probably caused by Giardia duodenalis, Assemblage F. Although infection was eliminated in most cats following treatment with fenbendazole, over 30% of the infected cats required a second treatment round (combined fenbendazole and metronidazole). Investigation of sensitivity to antibacterial drugs of E coli that had been isolated both prior to and following treatment demonstrated that fenbendazole treatment may select for resistant bacteria.

CONCLUSIONS AND RELEVANCE

Controlling Giardia infections in dense cat populations can be challenging, and requires strict hygiene measures. In cases where fenbendazole alone does not result in treatment success, a combination treatment with fenbendazole and metronidazole may be effective. Although this study did not include untreated controls, we suggest that the potential for changes in gut microbiota and antimicrobial resistance development should be considered when choosing antiprotozoal drugs, particularly in cases of treatment failure and where repeat treatment is required.

Histologic Features Associated with Tritrichomonas foetus-induced Colitis in Domestic Cats

Tritrichomonas foetus is a venereal pathogen of naturally bred cattle. In domestic cats, T. foetus colonizes the colon, resulting in chronic, large-bowel diarrhea. The infection is prevalent among young, densely housed cats, and there is no effective treatment. To the authors' knowledge, the characteristic microscopic lesions of T. foetus infection in naturally infected cats have not been described. The aim of the study reported here was to characterize the histologic changes in the colon of seven cats with T. foetus infection and chronic diarrhea. All cats were 1 year old or younger (mean, 6.7 ± 1.7 months), and a diagnosis of T. foetus infection was made on the basis of direct fecal smear examination (five cats), fecal culture in InPouch™ TF medium (four cats), single-tube nested polymerase chain reaction (PCR) analysis of DNA extracted from feces (two cats), or observation of trichomonads in sections of colon followed by PCR confirmation on DNA extracted from paraffin-embedded tissue (two cats). The presence of colonic trichomonads was the most diagnostic histologic feature. Organisms were identified in all cats, but in only 24 of 43 (56%) sections of colon. Trichomonads were generally present in close proximity to the mucosal surface and less frequently in the lumen of colonic crypts. The presence of colonic trichomonads was consistently associated with mild-to-moderate lymphoplasmacytic and neutrophilic colitis, crypt epithelial cell hypertrophy, hyperplasia and increased mitotic activity, loss of goblet cells, crypt microabscesses, and attenuation of the superficial colonic mucosa. In two of the cats, histologic lesions were more severe and were associated with invasion of trichomonads into the lamina propria and/or deeper layers of the colon.

Development of a Polymerase Chain Reaction Assay for the Detection of Antibiotic Resistance Genes in Community DNA

Many methods are used to detect antibiotic resistance genes in samples. The objective of the study reported here was to compare polymerase chain reaction (PCR) analysis of community DNA with fecal culturing for detecting antibiotic resistance genes in cattle samples. In the laboratory-based portion of this study, known concentrations of an Escherichia coli strain with 3 antibiotic resistance genes ( cmy-2, flo, and cat) were added to feces from dairy cattle. These genes were used to assess the effect of various primer pairs, chromosomally versus plasmid-encoded genes, and gene copy number on the sensitivity of PCR amplification. Gene-specific PCR amplification was performed on the community DNA extracted from the feces. Feces were cultured for the inoculated strain. In the field-based portion of the study, 80 cattle fecal samples of unknown gene status were compared by use of similar methods. Culture and PCR amplification from community DNA extractions produced variable results, and this variability was most noticeable at dilutions that approached the detection limit of the assay. Typically, PCR amplification had a higher sensitivity than did culture for detecting the gene of interest. However, the sensitivity of culture was improved by plating on selective media containing antibiotics. The community DNA approach enables assessment of bacterial communities in complex samples such as feces, a task that can be prohibitive by budget or time constraints associated with culture methods. Through a strategic combination of culture and community DNA approaches, the relationship between specific selection pressures and the persistence and dissemination of specific resistance genes can be elucidated.

Moving past serology: Diagnostic options without serum

•

Traditional serology has moved beyond blood as a test medium.

•

A number of different samples and tissues are now frequently used in veterinary diagnosis.

•

Testing can be robust and accurate and opens up the field to a variety of new opportunities.

•

Molecular testing allows direct testing for the agent on a variety of tissues and samples, and pools.

•

Pooling of samples can allow for more efficient and cost-effective testing.

Detecting antibodies formed in serum in response to infection is the traditional function of serology. Diagnostic modalities have included complement fixation tests, agar gel immune-diffusion, radioimmunoassay, ELISA and immunofluorescence. More recent technology now allows for the direct detection of pathogens by PCR. This review details the options for diagnostic testing using specimen types other than serum, identifying the advantages and disadvantages of these options and providing evidence for more widespread use of these techniques and specimen types.

Trichomonosis in cats with diarrhoea in Hong Kong, China, between 2009 and 2014

Case series summary

Infection of the domestic cat by Tritrichomonas blagburni, previously referred to as T foetus, may lead to a disease called feline trichomonosis, which manifests clinically as large bowel diarrhoea. The disease has a wide geographical distribution, including numerous countries in Europe, North America and Australia/Oceania. Nevertheless, it has occasionally been reported in Asia, South Korea and Japan. A retrospective study was carried out to include all domestic cats with diarrhoea, presented to two veterinary clinics in Hong Kong, China, between 1 July 2009 and 30 June 2014. A total of 29 cats with diarrhoea were diagnosed with Tritrichomonas species infection by means of quantitative PCR and direct microscopy. Tritrichomonas species was more frequently found in young (median age 10 months), male (66%) and purebred cats (86%). Giardia species was found in 31% of Tritrichomonas species-positive cats. The recommended dose of ronidazole (30 mg/kg q24h for 14 days) resolved clinical signs in 83% of diagnosed cats.

Relevance and novel information

This case series describes Tritrichomonas species as a cause for feline chronic diarrhoea in cats in China. The high rate of failure (17%) in those cats receiving a standard regimen of ronidazole might be due to owner or patient compliance rather than protozoal resistance to the drug.

Co-infection by Tritrichomonas foetus and Pentatrichomonas hominis in asymptomatic cats

Abstract: Tritrichomonas foetus, a parasite well known for its significance as a venereally transmitted pathogen in cattle, has been identified as a cause of chronic large bowel diarrhea in domestic cats in many countries of the world. In Brazil, several studies on the diagnosis of bovine trichomoniasis have been performed, but until now, no study was made regarding feline trichomoniasis. Thus, this is the first study to report the occurrence of T. foetus and Pentatrichomonas hominis in cats using morphological and molecular analysis. Feces from 77 cats were examined, four of which (5.2%) were positive for the presence of parabasalids. Morphological analysis of stained smears revealed piriform trophozoites showing the three anterior flagella, elongated nucleus and axostyle ending abruptly in fillet, characteristic of T. foetus. In scanning and transmission electron microscopy, identification characters similar to those previously reported for T. foetus were observed. The cultures containing trophozoites were submitted for molecular analysis, which resulted positive for T. foetus DNA using specific primers (TFR3 and TFR4), and all samples were positive and subjected to sequencing in which they showed 99.7-100% similarity with another isolate sequencing of T. foetus (JX960422). Although no trophozoite with consistent morphology of P. hominis has been visualized in the samples, differential diagnosis was performed using specific primers for P. hominis (TH3 and TH5) amplicon. In three of the four samples (3.89%) sequencing revealed 100% similarity when compared with another sequence of P. hominis deposited in Genbank (KC623939). Therefore, the present study revealed through the diagnostic techniques employed the simultaneous infection by T. foetus and P. hominis in the feces of cats. However, it was necessary to use more than one technique for the diagnosis of the co-infection. These results demonstrate the importance of a correct diagnosis to allow an appropriate treatment by the veterinarian.

A retrospective molecular study of select intestinal protozoa in healthy pet cats from Italy

The feline gut can harbour a number of protozoan parasites. Recent genetic studies have highlighted new epidemiological findings about species of Cryptosporidium, assemblages of Giardia duodenalis and Toxoplasma gondii. Furthermore, epidemiological studies suggest the occurrence of Tritrichomonas foetus in cats is on the increase worldwide. The prevalence of selected intestinal protozoa was determined by PCR using DNA previously extracted from the faeces of 146 privately owned healthy cats from Italy. Molecular genotyping on T gondii, G duodenalis and Cryptosporidium DNA was achieved. PCR assays were positive in 32 (22.9%) samples. Three animals (2.0%) were positive for T foetus and Cryptosporidium DNA, 15 specimens (10.3%) were positive for T gondii and 11 (7.5%) for G duodenalis. Co-infections were never observed. Results of the typing analysis allowed the identification of Cryptosporidium felis in all cases. The specimens positive for T gondii hinted at clonal genotype I (n = 7), genotype II (n = 1) and genotype III (n = 7). The G duodenalis isolates were referable to assemblages F (n = 9) and C (n = 2). In conclusion, the results obtained in this study add to the literature regarding the epidemiology of these parasites by confirming their presence in the faeces of healthy pet cats.

Nucleic acid-based differential diagnostic assays for feline coronavirus

•

A multiplex RT-PCR assay was developed to detect feline coronavirus.

•

To improve primer binding, inosine was used for primer design.

•

The assay could detect and differentiate FCoV, CCoV, and TGEV precisely.

Feline coronavirus (FCoV) is a pleomorphic, enveloped, positive-sense single-stranded RNA virus. Owing to the differences in its genotype, FCoV belongs to a separate clade along with other viruses, such as transmissible gastroenteritis virus (TGEV) and canine coronavirus (CCoV), which can be isolated from cats. In this study, a PCR assay was developed to differentiate these coronaviruses concurrently. Multiplex differential RT-PCR was performed with primers based on the highly conserved coronavirus membrane protein. Three primer sets were designed: a primer pair (S1 and S2) that can bind to conserved sequences in all target coronaviruses, a CCoV-specific primer (S3), and a TGEV-specific primer (S4). Because of the high sequence homology among FCoV, CCoV, and TGEV, a nucleotide preceding the last pair of dissimilar nucleotides in S3 and S4 was substituted with an inosine to allow primer binding. This assay could detect and differentiate FCoV (n = 7), CCoV (n = 4), and TGEV (n = 8) precisely and did not show any cross-reactivity with other pathogens. These results suggest that this molecular approach provides a rapid and reliable way to detect FCoV, especially in feline clinical specimens.

Enteropathogen co-infection in UK cats with diarrhoea

Background

Individual enteropathogen infections in healthy and clinically ill cats are well described, but prevalence and patterns of enteropathogen co-infection have only been reported on a limited basis. We studied enteropathogen co-infection in diarrhoeic UK cats using results of a real time PCR assay for 8 enteropathogenic species; feline coronavirus (Co), feline panleukopenia virus (Pa), Clostridium perfringens (Cl), Salmonella enterica (Sa), Giardia spp. (Gi), Tritrichomonas foetus (Tr), Cryptosporidium spp. (Cr), and Toxoplasma gondii (To). Age, gender, breed and history were recorded. PCR panels from 1088 diarrhoeic cats were available for analysis.

Results

Overall enteropathogen prevalence was 56.9% (Co), 22.1% (Pa), 56.6% (Cl), 0.8% (Sa), 20.6% (Gi), 18.8% (Tr), 24.4% (Cr) and 1.0% (To). Prevalence of Co, Gi and Tr was higher in pedigree cats compared to non-pedigree cats (DSH) and prevalence decreased with increasing age for Co, Pa, Gi, Cr and Tr. Co-infection was common: ≥2 enteropathogens were detected in 62.5% of cats, and 13.3% of cats had ≥4 enteropathogens. Mean ( x¯) enteropathogen co-infection 2.01 (±1.3 SD), was significantly higher in pedigree cats ( x¯ =2.51) compared to DSH ( x¯ =1.68) and decreased with age ( x¯ =2.64 <6 months, x¯ =1.68 for >1 yr). More cats were negative for all 8 enteropathogens tested (12.7%) than expected. When exact combinations of co-infection were examined, Tr tended to be found in combinations with Co, Cl, and Gi.

Conclusions

Multiple infections should be considered the most likely result of faecal testing in cats, and case management needs to take this into account. In contrast, the relatively high percentage of cats negative for all 8 enteropathogens tested could indicate an innate resistance to infection. Alternatively it could indicate a lack of exposure to these 8 enteropathogens or the presence of other enteropathogens not assessed by this assay.

Intestinal Tritrichomonas foetus infection in cats: a retrospective study of 104 cases

The clinical presentation and response to treatment of cats infected with Tritrichomonas foetus have not been sufficiently described in a large number of pet cats. The aim of this study was to collect and analyze clinical data from pet cats diagnosed with intestinal T foetus infection. Clinical information was collected for 104 cats that tested polymerase chain reaction-positive for T foetus. The most common clinical sign was diarrhea (98%) with a median duration of 135 days (range 1-2880 days). Forty-nine of 83 (59%) cats had diarrhea since adoption. Other clinical signs included anorexia (22%), depression (24%), weight loss or failure to gain weight (20%), vomiting (19%), abdominal pain (9%) and increased appetite (3%). A total of 45 cats had completed treatment with ronidazole, 29 of which (64%) showed a good clinical response to treatment. Sixteen (36%) cats had either partial or no improvement, or a relapse shortly after discontinuation of treatment.

Isolation of Tritrichomonas foetus from cats sampled at a cat clinic, cat shows and a humane society in southern Ontario

Tritrichomonas foetus is a protozoan parasite that has been associated with chronic diarrhea in cats. This study aimed to determine (i) the prevalence of T foetus shedding in cats from three different populations in southern Ontario, and (ii) associations between the presence of T foetus and potential cat management, health and demographic risk factors. A cross-sectional study was conducted involving 140 cats from a cat clinic in Guelph, 46 cats from a humane society in Guelph and 55 cats from two cat shows. Risk factor information was assessed through a questionnaire. The InPouch TF (feline) culture method was used to determine the presence of T foetus in all samples. Polymerase chain reaction was conducted on all samples positive by the InPouch TF, as well as 132 negative samples. The assays were interpreted in series and the prevalence of T foetus shedding and 95% confidence intervals (CI) were estimated at 0.7% (95% CI: 0.0-3.9%; n = 140) from the cat clinic, 0% (95% CI: 0.0-7.7%; n = 46) from the humane society and 23.6% (95% CI: 13.2-37.0%; n = 55) from the cat shows. 'Attendance at cat shows' was the only variable significant in both the univariable and multivariable analyses (P <0.05). No significant association was found between the presence of T foetus and diarrhea at the time of sampling or having a history of diarrhea in the past 6 months. The prevalence of T foetus was highly variable among populations of cats in southern Ontario, with shedding being most common in show cats.

Molecular determination of Tritrichomonas spp. in aborted bovine foetuses in Eastern Anatolian Region of Turkey

Tritrichomonas foetus is the causative agent of venereal trichomonosis in cattle causing infertility, pyometra and abortions. The objectives of this study were to determine the positivity rate of Tritrichomonas spp. in abomasal content of aborted foetuses from Eastern Anatolian Region of Turkey, using staining, culture and PCR methods and to present the isolates found in the region. A total of 246 abomasal content of aborted foetuses were tested and 14 of 246 (5.7%) were Tritrichomonas spp. positive only by polymerase chain reaction (PCR). Positivity was not attained by staining or culture method. Four of the positive samples in PCR were confirmed to be T. foetus by sequencing of the amplified 5.8S rRNA gene and flanking ITS regions. Nucleotide sequences of TR-Erzurum T. foetus isolates have been entered into the GenBank sequence database under accession numbers KC236423 through KC236426. This preliminary study suggests that future studies are needed on the systematic relationships and epidemiology of T. foetus isolates in the region.

Optimization of single-tube nested PCR for the diagnosis of visceral leishmaniasis

Conventional nested PCR is a very sensitive and specific method for the diagnosis of visceral leishmaniasis. However, this type of PCR is notorious for contamination problems related to the processing of the product between the first and the second PCR steps. In order to have a PCR method that is just as efficient but without the risk of contamination, we attempted the optimization of a single-tube nested PCR (STNPCR) method. During the first and the second PCR steps, we used the small subunit of ribosomal RNA (ssu rRNA) and the ribosomal internal transcribed spacer (ITS) as targets, respectively. The performances of STNPCR and nested PCR in detecting the DNA of Leishmania chagasi were compared. In the case of STNPCR, the inner primers were immobilized on the interior of the tube cap by means of adsorption microtubes and then were solubilized before the second reaction. This procedure eliminated the need to open the microtube, which could have led to false-positive results through cross-contamination. The detection limit for the purified L. chagasi DNA was 1 fg by using nested PCR and 10 fg by using STNPCR. We also tested the specificity of the system against other parasites, and observed that Trypanosoma cruzi DNA was amplified with a detection limit of up to 1 pg. This study not only presents a promising tool for the diagnosis of visceral leishmaniasis, but also provides a new tool for the diagnosis of Chagas disease, either in mono-infection by T. cruzi or in co-infection with Leishmania spp.

Prevalence of Tritrichomonas foetus infections in French catteries

Recently, Tritrichomonas foetus, the known etiologic agent of bovine trichomonosis was identified in domestic cats in many countries around the world. In felids, this parasite would be a significant cause of large-bowel diarrhoea. Therefore the aim of the present study was to determine for the first time the prevalence of T. foetus infection in French catteries. In this epidemiological survey, rectal swabs from 140 cats participating in three international shows were tested for the presence of motile parasites by microscopy after culturing. The prevalence of T. foetus infection was 14.3% among cats (20/140) and 15.9% among catteries (18/117). These values were similar to those previously obtained in other European countries. Except for the age, no significant associations were found between the presence of T. foetus and various risk factors of infection such as the size of the cattery, the type of food, or the vicinity of a dog. Internal transcribed region of the ribosomal DNA unit was sequenced from the 20 T. foetus isolates identified in this study. They exhibited 100% identity and are homologous with other sequences of strains isolated from domestic cats in other countries.

Loop mediated isothermal amplification of 5.8S rDNA for specific detection of Tritrichomonas foetus

Tritrichomonas foetus is the causative agent of bovine trichomonosis, a sexually transmitted disease leading to infertility and abortion. A test based on loop mediated isothermal amplification (LAMP) targeting the 5.8S rDNA subunit was designed for the specific identification of T. foetus. The LAMP assay was validated using 28 T. foetus and 35 non-T. foetus trichomonads strains. It did not exhibit cross-reaction with closely related parasites commonly found in smegma cultures like Tetratrichomonas spp. and Pentatrichomonas hominis. Bovine smegma did not show interferences for the detection of the parasite and, the sensitivity of the method (4 × 10³ CFU/mL, approximately 10 cells/reaction) was slightly higher than that found for PCR amplification with TFR3 and TFR4 primers. The LAMP approach has potential applications for diagnosis and control of T. foetus and, practical use for low skill operators in rural areas.

Molecular survey of Tritrichomonas suis (=T. foetus) 'cat' and 'cattle' genotypes in pigs in Japan

Tritrichomonas suis (=T. foetus) is a protozoan parasite of pigs, cattle and cats. Based on host range and genetic differences, T. suis has been divided into a 'cat genotype' and a 'cattle genotype', with the latter genotype capable of infecting both cattle and pigs. Since no information is currently available on the genetic characteristics of T. suis from pigs in Japan, we conducted a molecular survey of T. suis using fecal DNA from pigs in Japan. Of the 64 pigs examined, nested PCR revealed that 36 (56.3%) were positive for T. suis. Sequence analysis of 8 positive samples showed that 7 of the pig isolates belonged to the 'cattle genotype' and the remaining isolate belonged to the 'cat genotype'. The findings revealed that T. suis infection is common in pigs in Japan and that pigs can be infected by both genotypes.

Feline Tritrichomonas foetus adhere to intestinal epithelium by receptor-ligand-dependent mechanisms

Tritrichomonas foetus (TF) is a protozoan that infects the feline ileum and colon resulting in chronic diarrhea. Up to 30% of young purebred cats are infected with TF and the infection is recognized as pandemic. Only a single drug, characterized by a narrow margin of safety and emerging development of resistance, is effective for treatment. While the venereal pathogenicity of bovine TF is attributed to adherence to uterovaginal epithelium, the pathogenesis of diarrhea in feline TF infection is unknown. The aim of this study was to establish an in vitro model of feline TF adhesion to intestinal epithelium. Confluent monolayers of porcine intestinal epithelial cells (IPEC-J2) were infected with axenic cultures of feline TF that were labeled with [(3)H] thymidine or CFSE and harvested at log-phase. The effect of multiplicity and duration of infection, viability of TF, binding competition, formalin fixation and cytoskeletal inhibitors on adherence of feline TF to IPEC-J2 monolayers was quantified by liquid scintillation counting and immunofluorescence. [(3)H] thymidine and CFSE-labeled TF reproducibly adhered to IPEC-J2 monolayers. Clinical isolates of feline TF adhered to the intestinal epithelium in significantly greater numbers than Pentatrichomonas hominis, the latter of which is a presumably nonpathogenic trichomonad. Adhesion of TF required viable trophozoites but was independent of cytoskeletal activity. Based on saturation and competition binding experiments, adherence of feline TF to the epithelium occurred via specific receptor-ligand interactions. The developed model provides a valuable resource for assessing pathogenic mechanisms of feline TF and developing novel pharmacologic therapies for blocking the adhesion of feline TF to the intestinal epithelium.

Efficacy of ronidazole for treatment of cats experimentally infected with a Korean isolate of Tritrichomonas foetus

To evaluate the efficacy of ronidazole for treatment of Tritrichomonas foetus infection, 6 Tritrichomonas-free kittens were experimentally infected with a Korean isolate of T. foetus. The experimental infection was confirmed by direct microscopy, culture, and single-tube nested PCR, and all cats demonstrated trophozoites of T. foetus by day 20 post-infection in the feces. From day 30 after the experimentally induced infection, 3 cats were treated with ronidazole (50 mg/kg twice a day for 14 days) and 3 other cats received placebo. Feces from each cat were tested for the presence of T. foetus by direct smear and culture of rectal swab samples using modified Diamond's medium once a week for 4 weeks. To confirm the culture results, the presence of T. foetus rRNA gene was determined by single-tube nested PCR assay. All 3 cats in the treatment group receiving ronidazole showed negative results for T. foetus infection during 2 weeks of treatment and 4 weeks follow-up by all detection methods used in this study. In contrast, rectal swab samples from cats in the control group were positive for T. foetus continuously throughout the study. The present study indicates that ronidazole is also effective to treat cats infected experimentally with a Korean isolate of T. foetus at a dose of 50 mg/kg twice a day for 14 days.

Open-label trial of a multi-strain synbiotic in cats with chronic diarrhea

This study was designed to test the hypothesis that in cats with chronic diarrhea the daily administration of a proprietary synbiotic (Proviable-DC) would result in an improvement in stool character, as assessed by the owner. Adult cats with chronic diarrhea were recruited for the study and screened for systemic diseases. Fecal flotation, wet mount, immunofluorescence assay (IFA) for Giardia and Cryptosporidium species, and Tritrichomonas species polymerase chain reactions (PCRs) were used to screen for intestinal parasitism. The synbiotic was administered for 21 days; otherwise, no changes were made to ongoing treatment(s) or diet. The severity of the diarrhea was assessed using a standardized fecal scoring system and the owner's subjective perception before, and after, supplementation. The mean fecal score for the 53 cats completing the study decreased from 6.0 to 4.4, representing a significantly (P <0.001) firmer stool character. Seventy-two percent of owners perceived an improvement in their cat's diarrhea following a 21-day course of synbiotic supplementation.