Browsing by Author "Lappin, Michael, advisor"

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Open Access
A study of factors associated with Giardia and Cryptosporidium infections in humans, dogs and cats in the USA
(Colorado State University. Libraries, 2016) Thigeel, Hanaa, author; Lappin, Michael, advisor; Olea-Popelka, Francisco, advisor; Twedt, David, committee member; Hyatt, Doreene, committee member
Giardia spp. and Cryptosporidium spp. are two of the leading causal agents of parasitic diarrhea in humans, dogs and cats. The two pathogens contain both host-adapted and zoonotic strains and dogs and cats can harbor both strains. There is critical need to understand factors potentially associated with the risk and prevalence of infection due to Giardia spp. and Cryptosporidium spp. in dogs, cats and humans. This will ultimately aid in disease management and control. Furthermore, molecular characterization of the human, dog or cat isolates may identify zoonotic genotypes and may provide further information concerning the transmission routes between humans, dogs and cats. In Chapter 1, a review of literature regarding Giardia duodenalis and Cryptosporidium spp. in humans and companion animals (dogs and cats) was conducted. The review involves a brief description of the two pathogens’ current taxonomy, epidemiology, and diagnostic methods. Chapter 2 presents a retrospective study designed to analyze results from dog and cat polymerase chain reaction (PCR) panels from the commercial laboratory, ANTECH Diagnostics. The main purpose of this study was to evaluate associations between the probability of testing positive to Giardia spp. and Cryptosporidium spp. and risk factors such as animal’s age, sex, region, and season. The results of this study showed that age (younger animals) was significantly associated with the risk of PCR positive results for Giardia spp. and Cryptosporidium spp. in both dogs and cats. Region was significantly associated with Cryptosporidium spp. in both dogs and cats, whereas season was only associated with Giardia spp. in dogs. Chapter 3 describes the validation and optimization a previously published 60 kDa glycoprotein (gp60) gene-based PCR assay. The objective of this study was to use the assay to subtype C. parvum and C. hominis isolated from human fecal samples. The analytical sensitivity of this PCR assay was determined by assaying serial dilutions of C. parvum oocysts and C. hominis DNA. The analytic specificity was determined by assaying Cryptosporidium and non-Cryptosporidium spp. DNA. The gp60 PCR assay consistently detected DNA of C. parvum if oocysts were present at 104/mL. The assay was detected the DNA of C. hominis in the lowest concentration. In Chapter 4, a prospective study was conducted to assess the risk of factors potentially associated with Giardia duodenalis and Cryptosporidium spp. infections and estimate the prevalence of these two pathogens in senior veterinary students and their pet dogs and cats. A structured questionnaire was developed to assess a baseline exposure of the students to large and small animals. In addition, a single voluntary sample was requested from students and their dogs or cats that live within the household. Giardia duodenalis and Cryptosporidium spp. were detected by the PCR and immunofluorescence (IFA) assays in students and their dogs and cats. As a result of the recruitment, 51 surveys, 42 human fecal samples, 31 dog fecal samples, and 17 cat fecal samples were collected. Clinical rotation, track preference, gender, pet ownership and farm exposure were factors selected to be evaluated for the risk of both pathogens in senior veterinary students. As a result of this evaluation, none of these factors selected was statistically associated with the risk of infection due to G. duodenalis or Cryptosporidium spp. All Giardia isolated from dogs were host-adapted assemblages. However, a zoonotic Cryptosporidium genotype (C. parvum subtype family IIa) was identified in one human sample. The analysis conducted in this dissertation provided an evaluation of potential risk factors associated with giardiasis and cryptosporidiosis in pet dogs and cats. The results of this research enhanced the understanding of the disease prevalence of Giardia spp. and Cryptosporidium spp. among senior veterinary students and their dogs and cats. The survey collected valuable and novel information on the students’ characteristics, student health status, their pets’ health status and activities that may have led to an increased risk of infection during their clinical rotations or intense handling of small or large animals. The analysis of the survey provided an evaluation of potential risk factors associated with the risk of infection in senior veterinary students. Molecular analysis of isolates of human, dog and cat origin helped in differentiating between G. duodenalis assemblages and Cryptosporidium spp. genotypes. Future directions may include an evaluation for associations of positive test results with clinical findings and further studies determining the likelihood dogs or cats are carrying zoonotic Giardia spp. or Cryptosporidium spp.. National research is recommended to be conducted to identify risk factors in veterinary students from different states in the United States. Additionally, a larger study should be performed to determine the baseline exposure of veterinary school faculty, specifically, those who work on large animal rotations and collect fecal samples from their pet dogs and cats to for genotyping to detail whether zoonotic infections with these two protozoans occur.
Open Access
Assessment of novel causes and investigation into the gut microbiome in cats with chronic kidney disease
(Colorado State University. Libraries, 2020) Summers, Stacie, author; Lappin, Michael, advisor; Quimby, Jessica, committee member; Dow, Steve, committee member; Prenni, Jessica, committee member
To view the abstract, please see the full text of the document.
Open Access
Coagulation abnormalities in Ehrlichia canis-infected dogs and detection and dynamics of anti-platelet antibodies in thrombocytopenic dogs
(Colorado State University. Libraries, 2018) Shropshire, Sarah, author; Lappin, Michael, advisor; Dow, Steve, committee member; Olver, Christine, committee member; Webb, Craig, committee member; Ames, Marisa, committee member
Vector-borne diseases affect millions of people and domestic animals worldwide resulting in significant morbidity and mortality rates. In dogs, vector-borne diseases such as Ehrlichia canis can cause a myriad of clinical signs (lethargy, weight loss, and epistaxis) and hematological abnormalities (hyperglobulinemia, thrombocytopenia, and anemia). It has been previously reported that E. canis results in systemic inflammation and vasculitis as well as the formation of immunoglobulin associated platelets or anti-platelet antibodies. It has been theorized that anti-platelet antibodies can deleteriously affect platelet function and if concurrent significant thrombocytopenia is present, signs of bleeding may manifest. However, anti-platelet antibodies and thrombocytopenia can occur in a variety of disease processes in the dog including other vector-borne diseases, neoplasia, and idiopathic primary immune syndromes. Thrombocytopenia is also one of the most common acquired hemostatic abnormality observed in dogs. Consequently, determining the underlying cause and mechanism for thrombocytopenia in dogs can represent a frequent diagnostic challenge. Additionally, inflammation is often present in dogs with thrombocytopenia due to various causes. Inflammation and immune system processes directly affect hemostasis which can lead to derangements in the coagulation system resulting in clinical signs of bleeding or thrombosis. The goals of the research described in this dissertation were to investigate the dynamic changes of anti-platelet antibodies in thrombocytopenic dogs and the changes that occur in the coagulation system during a vector-borne infection such as E. canis in dogs.
Open Access
Development and application of new diagnostic assays for the detection of Bartonella henselae infection in cats
(Colorado State University. Libraries, 2013) Assarasakorn, Sukullaya, author; Lappin, Michael, advisor; Veir, Julia, committee member; Jensen, Wayne, committee member; Hill, Ashley, committee member; Hyatt, Doreene, committee member
To view the abstract, please see the full text of the document.
Open Access
Feline chronic kidney disease: novel approaches to etiology, specific therapy and supportive care
(Colorado State University. Libraries, 2012) Quimby, Jessica M., author; Dow, Steve, advisor; Lappin, Michael, advisor; Lunn, Katharine, committee member; Olver, Christine, committee member
Chronic kidney disease is one of the leading causes of morbidity and mortality in geriatric cats, affecting conservatively 30% of the population; an estimated 24 million cats nationwide in the United States. Despite the common nature of the disease, its etiology is yet unknown, and there is no definitive cure short of renal transplantation. The goals of the research described in this dissertation were to explore possible etiologies of chronic kidney disease and to develop novel treatment strategies to help cats afflicted with this disease. The first part of this project investigated a possible etiology for CKD; renal aging as manifested by telomere shortening and cellular senescence. In these studies telomere length and cellular senescence were assessed in cats with CKD in comparison to young healthy and geriatric healthy controls. Using a TELI-FISH assay to measure telomere length in specific renal cell populations, significantly shorter telomeres were found in the renal proximal and distal tubular cell population of CKD cats compared to young normal or geriatric normal cats. There was no difference between CKD cats and normal cats when liver or skin telomere length was measured. Additionally, β-galactosidase assay revealed increased cellular senescence in the kidneys of CKD cats in comparison to young normal. CKD cats tended to have increased β-galactosidase staining in comparison to normal geriatric cats, but this did not reach statistical significance. Neither telomere length nor cellular senescence were correlated with age, but the normal geriatric population available for assessment was small. It was concluded that telomere shortening and cellular senescence are present in feline CKD; future studies will be necessary to determine cause and effect aspects of this relationship. Demonstration of an association between telomere shortening, cellular senescence and feline CKD could be the foundation of new treatment strategies. Cats with CKD frequently have poor appetites and nutritional management of these patients is important. Mirtazapine is an appetite stimulant and anti-nausea medication that has recently gained popularity in veterinary medicine and anecdotally appears to be helpful for the management of appetite. However, no pharmacokinetic or pharmacodynamic information exists on the drug in cats. The aims of the second part of these studies were a) the assessment of the pharmacokinetics and pharmacodynamics of commonly prescribed doses of mirtazapine in normal cats, elderly cats and cats with CKD, and b) a placebo-controlled blinded crossover clinical trial to assess the efficacy of mirtazapine in CKD cats. These studies demonstrated that there are differences in the metabolism of mirtazapine between young normal cats, geriatric normal cats and CKD cats. Based on the pharmacokinetic studies, young cats could receive daily mirtazapine at a low dose without significant likelihood of drug accumulation whereas CKD cats should receive the drug every other day due to delayed clearance. In a subsequent clinical trial, mirtazapine significantly increased appetite, activity and weight in CKD cats when administered at a low dose every other day for three weeks. Additionally, a significant decrease in vomiting was noted. This demonstrated that mirtazapine does have significant appetite stimulating and anti-nausea effects in CKD cats. The information gathered in this body of work will help clinicians prescribe mirtazapine more effectively with a decreased incidence of unwanted drug side effects. Most importantly, it will help improve the quality of life and potentially prognosis of cats suffering from CKD. Most treatments for CKD are palliative in nature and do not directly address the underlying pathology. CKD is characterized by tubulointerstitial inflammation, fibrosis and progressive loss of renal function. Mesenchymal stem cell (MSC) therapy is thought to be anti-inflammatory, and has the potential to improve or stabilize renal function in animals with renal failure, based on evidence from rodent model studies of induced renal disease. At present, there is little published work regarding the use of MSC for treatment of naturally occurring CKD. The last section of this body of work focuses on the evaluation of MSC therapy as a novel treatment strategy for cats with CKD. A series of pilot studies was performed; a pilot study of intrarenal injection of autologous stem cells and two pilot studies of intravenously injected allogeneic cryopreserved MSC. Urinary cytokines were measured to assess intra-renal inflammation, fibrosis and vascular health and the possible effects of MSC injection on these factors. We determined that MSC could be successfully harvested and cultured from bone marrow and adipose sources, but the latter was preferred for ease of collection, expansion and superior yield. Intrarenal injection did not induce immediate or longer-term adverse effects. Two CKD cats that received intrarenal adipose-derived MSC experienced modest improvement in GFR and a mild decrease in serum creatinine concentration. In the allogeneic cryopreserved intravenous study, six cats received 2 x 106 MSC per injection and experienced a significant decrease in serum creatinine with negligible side effects. Five cats received 4 x 106 MSC per injection and side effects included vomiting during infusion and increased respiratory rate. Variable decreases in serum creatinine, increases in GFR by iohexol clearance and changes in urinary cytokines were seen. Despite the mild improvement in creatinine seen in some of the cats, none had improvement to the extent described in rodent models. While MSC therapy potentially holds promise for palliation of CKD, additional work is necessary to determine if this therapy can be manipulated to increase its efficacy. The work described in this dissertation has increased our knowledge of the biology of renal aging and its relationship to CKD. In addition it has assessed the effect of two novel treatment strategies on cats with CKD. This information will directly improve the lives of cats with CKD as well as providing a strong foundation for further research in this area.
Open Access
Molecular epidemiology of Giardia and Cryptosporidium in dogs and cats in Chiang Mai, Thailand
(Colorado State University. Libraries, 2013) Tangtrongsup, Sahatchai, author; Salman, Mo, advisor; Lappin, Michael, advisor; Ballweber, Lora, committee member; Reif, John, committee member
Giardia duodenalis and Cryptosporidium spp. are the common causes of diarrhea in humans and animals, including domestic and wildlife, throughout the world. The species complex G. duodenalis and the genus Cryptosporidium consist of host-adapted and zoonotic genotypes/species. Companion animals, especially dogs and cats, can be infected by the host-adapted as well as the zoonotic genotype/species of these organisms. Therefore, these animals have been questioned regarding their potential to serve as reservoirs for human transmission. In this dissertation, an epidemiological study of Giardia and Cryptosporidium as well as the molecular characterization of these organisms in dogs and cats in Chiang Mai, Thailand was completed. A greater understanding of the prevalence and risk factors associated with Giardia and Cryptosporidium infection can aid veterinarians in the control and prevention of these important diseases. Furthermore, the potential for zoonotic transmission will be reduced. In Chapter 1, Giardia and Cryptosporidium and its epidemiology in dogs and cats are reviewed as well as an update on the situation regarding giardiasis and cryptosporidiosis in Thailand. In Chapter 2, a preliminary study to determine the prevalence of Giardia and Cryptosporidium infection in dogs and cats in Chiang Mai, Thailand is described. Fecal samples were collected for two months (July and August, 2008). The genotype/species of these two organisms were determined as well as the risks associated with infection such as age, sex, diarrhea status, housing type and the presence of co-infection of Cryptosporidium (for Giardia infection) or the presence of Giardia in the case of Cryptosporidium infection. It was shown that Giardia and Cryptosporidium infections were common in dogs in Chiang Mai and that dogs could be a potential reservoir for zoonotic transmission to humans. In Chapter 3, the larger cross-sectional study is described. Samples were collected a year later from August 2009 to February 2010. The objectives were to determine the effect of seasonality (wet months or rainy vs. dry months or winter), to determine the potential risk factors associated with Giardia and Cryptosporidium infections, as well as to determine the genotype/species of these organisms. The results suggested that Giardia infection in dogs was prevalent in the rainy season, whereas seasonality was not significantly associated with Cryptosporidium infection. Young dogs, dogs living in crowded settings, dogs having diarrhea or chronic diarrhea, and dogs shedding Cryptosporidium oocysts had a high risk for Giardia infection. Risk factors associated with Cryptosporidium infection in dogs were age less than one year and dogs having diarrhea. Giardia duodenalis assemblage A and C. parvum were identified in this study; however, the potential role in zoonotic transmission could not be determined. Chapter 4 presents a brief report on the comparison of sugar and sedimentation concentration techniques prior to immunofluorescent assay to detect Giardia cysts and Cryptosporidium oocysts. Concentration of fecal samples may enhance the detection of cysts and oocysts. However, in frozen samples the spherical structure of Giardia cysts or Cryptosporidium oocysts may be affected by the freeze-and-thaw process; therefore, the use of sugar concentration technique may not appropriate for frozen fecal samples. Chapter 5 compares the PCR assays using different target genes in detecting Giardia and Cryptosporidium in dogs and cats from Chiang Mai, Thailand. Three PCR assays for Giardia were compared, including the PCR targeting to glutamate dehydrogenase (gdh), triose phosphate isomerase (tpi), and β-giardin gene. Three PCR assays for Cryptosporidium, a heat shock protein targeting PCR and two PCR assays to detect SSU-rRNA (one step PCR vs nested PCR assays), were compared. Giardia gdh and Cryptosporidium one-step SSU-rRNA PCR assays had the highest amplification rates. Using a multilocus analysis approach, most of the Giardia isolates were dog genotypes, whereas 30%-40% of Cryptosporidium species were C. parvum. This finding may suggest a potential role of zoonotic transmission of Cryptosporidium from dogs and cats in this region of Thailand. The research described in this dissertation raises the knowledge in the field of canine and feline giardiasis and cryptosporidiosis. The results provide additional prevalence and risk analysis results for dogs and cats in Chiang Mai, Thailand. The molecular analyses suggest that the use of multilocus analysis is superior to using only one locus. In addition, the results also suggest that sugar flotation was not appropriate as a concentrating method for frozen fecal material and that sedimentation should be used when freezing of the sample is necessary.
Open Access
Pathology of feline chronic kidney disease: histomorphologic characterization of renal and gastric lesions; and an investigation into the expression of renal α-enolase
(Colorado State University. Libraries, 2015) McLeland, Shannon M., author; Dow, Steve, advisor; Lappin, Michael, advisor; Callan, Robert, committee member; Duncan, Colleen, committee member; Quimby, Jessica, committee member
To view the abstract, please see the full text of the document.