ACVIM consensus statement on the treatment of immune thrombocytopenia in dogs and cats.

Management of immune thrombocytopenia (ITP) in dogs and cats is evolving, but there are no evidence-based guidelines to assist clinicians with treatment decisions. Likewise, the overall goals for treatment of ITP have not been established. Immunosuppressive doses of glucocorticoids are the first line treatment, but optimal treatment regimens beyond glucocorticoids remain uncertain. Additional options include secondary immunosuppressive drugs such as azathioprine, modified cyclosporine, and mycophenolate mofetil, usually selected based on clinician preference. Vincristine, human IV immunoglobulin (hIVIg), and transfusion of platelet or red blood cell-containing products are often used in more severe cases. Splenectomy and thrombopoietin receptor agonists are usually reserved for refractory cases, but when and in which patient these modalities should be employed is under debate. To develop evidence-based guidelines for individualized treatment of ITP patients, we asked 20 Population Intervention Comparison Outcome (PICO) format questions. These were addressed by 17 evidence evaluators using a literature pool of 288 articles identified by a structured search strategy. Evidence evaluators, using panel-designed templates and data extraction tools, summarized evidence and created guideline recommendations. These were integrated by treatment domain chairs and then refined by iterative Delphi survey review to reach consensus on the final guidelines. In addition, 19 non-PICO questions covering scenarios in which evidence was lacking or of low quality were answered by expert opinion using iterative Delphi surveys with panelist integration and refinement. Commentary was solicited from multiple relevant professional organizations before finalizing the consensus. The rigorous consensus process identified few comparative treatment studies, highlighting many areas of ITP treatment requiring additional studies. This statement is a companion manuscript to the ACVIM Consensus Statement on the Diagnosis of Immune Thrombocytopenia in Dogs and Cats.

Multi-institutional retrospective study investigating blood culture protocols and test positivity in 701 dogs.

Objectives: (i) To determine the influence of specimen collection protocol (timing and specimen quantity), primary disease process, and pre-existing antimicrobial or immunosuppressive therapy on blood culture (BC) positivity and (ii) To determine agreement between urine culture and BC results. Animals: 701 client-owned dogs. Methods: Multi-institutional retrospective study (2019-2022). Mixed-effect logistic regression was used to determine whether primary disease process, the number of BCs, or the timing of specimen collection was associated with BC positivity. Prediction plots were generated. Associations between urine culture and BC results were performed using logistic regression. Results: Dogs with a positive urine culture were more likely to have a positive BC (OR: 4.36, 95% CI: 2.12-8.97, p = 0.003). Dogs that had three BC specimens had the greatest odds of obtaining a positive BC result (adjusted predictive value: 0.44, 95% CI: 0.21-0.70), although this was not significant. Isolates from 38.5% of dogs with a positive BC had resistance to ≥3 antimicrobial classes. The timing between specimen collection had no significant association with BC positivity. Pre-existing antibiotic or immunosuppressive therapy had no significant association with BC positivity. Clinical relevance: Dogs with a positive urine culture were more likely to have a positive BC result.

Prevalence of antibiotic use for dogs and cats in United States veterinary teaching hospitals, August 2020.

BACKGROUND: Awareness of prescribing practices helps identify opportunities to improve antibiotic use (AU). OBJECTIVES: To estimate AU prevalence in dogs and cats in U.S. veterinary teaching hospitals (VTHs) and identify antibiotic drugs commonly prescribed, indications for use, and evidence of bacterial infection. ANIMALS: Medical record data were collected from dogs and cats examined at 14 VTHs. METHODS: Data were collected from VTH medical records of dogs and cats examined by primary care, urgent care, emergency and critical care, internal medicine, and surgery services on a single day during August 13-September 3, 2020. Data included signalment; clinical service; inpatient or outpatient status; clinical conditions; diagnostic tests; evidence of bacterial infection; intended reason for AU; name and route of antibiotics prescribed. RESULTS: Of 883 dogs and cats, 322 (36.5%) were prescribed at least 1 antibiotic. Among 285 antibiotics administered systemically intended for treatment of infection, 10.9% were prescribed without evidence of infection. The most common class of antibiotics presribed for systemic administration was potentiated penicillin for dogs (115/346, 33.3%) and cats (27/80, 33.8%). For dogs and cats, first-generation cephalosporins (93/346, 26.9% and 11/80, 13.8%, respectively) and fluoroquinolones (51/346, 14.7% and 19/80, 23.8%, respectively) was second or third most-prescribed. Common AU indications included skin, respiratory, and urinary conditions, and perioperative use. CONCLUSIONS AND CLINICAL IMPORTANCE: Collaborative data collection provides a sustainable methodology to generate national AU prevalence estimates and bring attention to areas requiring additional research and detailed data collection. These efforts can also identify practice improvement opportunities in settings where future veterinarians are trained.

Demonstrating the importance of local culture and susceptibility data: antibiograms from dogs at a veterinary tertiary care center.

OBJECTIVE: To create antibiograms for commonly cultured organisms in a small animal tertiary care hospital following Clinical and Laboratory Standards Institute guidelines and to compare these local resistance patterns to published first-tier antimicrobial recommendations. SAMPLE: Urine (n = 429), respiratory (41), and skin (75) isolates cultured from dogs between January 1, 2019, and December 31, 2020, at the Tufts University Foster Hospital for Small Animals. PROCEDURES: MIC and susceptibility interpretations were recorded for multiple sites for 2 years. Sites with greater than 30 isolates for at least 1 organism were included. Urinary, respiratory, and skin antibiograms were created using Clinical and Laboratory Standards Institute breakpoints and guidelines. RESULTS: Urinary Escherichia coli had a higher susceptibility percentage for amoxicillin-clavulanate (80% [221/275]) than amoxicillin alone (64% [175/275]). Respiratory E coli were greater than 80% susceptible to only 2 antimicrobials (imipenem, amikacin). Of skin Staphylococcus pseudintermedius isolates, 40% (30/75) were methicillin-resistant and frequently also displayed resistance to non-beta lactam antimicrobials. Susceptibility to recommended first-line antimicrobials varied and was greatest for gram-negative urinary isolates and lowest for methicillin-resistant S pseudintermedius skin isolates and respiratory E coli. CLINICAL RELEVANCE: Local antibiogram creation identified frequent resistance that may preclude the use of guideline-recommended first-line therapy. High levels of resistance identified in methicillin-resistant S pseudintermedius isolates supports growing concern for methicillin-resistant staphylococci in veterinary patients. This project highlights the need for population-specific resistance profiles to be used in conjunction with national guidelines.

Impact of antimicrobial use in dogs on antimicrobial resistance and shared flora with human owners.

Transmission of bacteria between animals and humans in domestic households is increasingly recognized. We evaluated the presence of antimicrobial-resistant fecal bacteria in 8 dog-owner-dog pairs before and after the dog received amoxicillin-clavulanate. The study identified shared flora in the humans and dogs that were affected by antimicrobial administration.

Thromboelastography in cats with cholestatic liver disease.

OBJECTIVES: While thromboelastography (TEG) has helped define a complex state of hemostasis in dogs and humans with hepatobiliary disease, it has not been explored in cats with cholestatic liver disease (CLD). The objective of this study was to describe TEG parameters in cats with CLD and to compare these parameters with conventional plasma-based coagulation tests, white blood cell (WBC) count and biochemical indicators of liver disease grade and severity. METHODS: Eighteen cats with CLD, defined by a serum bilirubin ⩾3 mg/dl and a greater than two-fold increase in serum alanine aminotransferase (ALT) and/or alkaline phosphatase (ALP) activity, were prospectively enrolled. All cats received vitamin K1 subcutaneously for 24-36 h prior to acquisition of blood for kaolin-activated TEG analysis, prothrombin time (PT) and activated partial thromboplastin time (aPTT). Patient total solids, packed cell volume, platelet count, WBC count, and serum liver enzymes and bilirubin were extracted from the medical record and correlated with coagulation test results. RESULTS: TEG global clot strength (TEG G) values defined 9/18 (50%), 5/18 (28%) and 4/18 (22%) cats as hypercoagulable, normocoagulable or hypocoagulable, respectively. TEG G was significantly negatively correlated with PT, aPTT and serum ALP activity and positively correlated with total solids. Five cats (5/18, 28%) were hyperfibrinolytic with clot lysis at 60 mins (LY 60) >15.3%. LY 60 was significantly positively correlated with PT. CONCLUSIONS AND RELEVANCE: By TEG analysis, cholestatic cats replete with vitamin K1 display a variety of coagulation profiles. Indications of synthetic failure (prolonged PT and aPTT) were associated with hypocoagulable and hyperfibrinolytic TEG parameters. High disease activity (serum ALP) was associated with a hypocoagulable state.

Effects of oral administration of 5 immunosuppressive agents on activated T-cell cytokine expression in healthy dogs.

BACKGROUND: Dogs are often adminstered >1 immunosuppressive medication when treating immune-mediated diseases, and determining whether these different medications affect IL-2 expression would be useful when performing pharmacodynamic monitoring during cyclosporine therapy. HYPOTHESIS/OBJECTIVES: To determine the effects of 5 medications (prednisone, cyclosporine, azathioprine, mycophenolate mofetil, and leflunomide) on activated T-cell expression of the cytokines IL-2 and interferon-gamma (IFN-γ). ANIMALS: Eight healthy dogs. METHODS: Randomized, cross-over study comparing values before and after treatment, and comparing values after treatment among drugs. Dogs were administered each drug at standard oral doses for 1 week, with a washout of at least 21 days. Activated T-cell expression of IL-2 and IFN-γ mRNA was measured by quantitative reverse transcription polymerase chain reaction. Blood drug concentrations were measured for cyclosporine, mycophenolate, and leflunomide metabolites. RESULTS: Least squares means (with 95% confidence interval) before treatment for IL-2 (2.91 [2.32-3.50] ΔCt) and IFN-γ (2.33 [1.66-3.00 ΔCt]) values were significantly lower (both P < .001) than values after treatment (10.75 [10.16-11.34] and 10.79 [10.11-11.46] ΔCt, respectively) with cyclosporine. Similarly, least squares means before treatment for IL-2 (1.55 [1.07-2.02] ΔCt) and IFN-γ (2.62 [2.32-2.92] ΔCt) values were significantly lower (both P < .001) than values after treatment (3.55 [3.06-4.00] and 5.22 [4.92-5.52] ΔCt, respectively) with prednisone. Comparing delta cycle threshold values after treatment among drugs, cyclosporine was significantly different than prednisone (IL-2 and IFN-γ both P < .001), with cyclosporine more suppressive than prednisone. CONCLUSIONS AND CLINICAL IMPORTANCE: Prednisone and cyclosporine both affected expression of IL-2 and IFN-γ, suggesting that both have the ability to influence results when utilizing pharmacodynamic monitoring of cyclosporine treatment.

Recovery of T-cell function in healthy dogs following cessation of oral cyclosporine administration.

Cyclosporine is a potent immunosuppressive agent used to treat immune-mediated disorders in dogs. Secondary infections sometimes necessitate withdrawal of cyclosporine, but it is not known how long it takes for the immune system to recover after cessation of cyclosporine. Our goal was to utilize a validated RT-qPCR assay in dogs to assess recovery time of the T-cell cytokines IL-2 and IFN-γ after discontinuation of cyclosporine. Six healthy dogs were given oral cyclosporine (10 mg/kg every 12 hr) for 1 week, with samples collected for measurement of cytokine gene expression prior to treatment, and on the last day of therapy. Cyclosporine was then discontinued, and samples were collected daily for an additional 7 days. Results revealed that there was a significant difference in cytokine expression when comparing pre-treatment and immediate post-treatment values, corresponding to marked suppression of T-cell function. There was no significant difference between pre-treatment values for either cytokine when compared with any day during the recovery period. Cytokine expression, evaluated as a percentage of pre-treatment baseline samples, demonstrated progressing return of T-cell function after drug cessation, with full recovery seen in all dogs by Day 4 of the recovery period.

Effects of pentoxifylline on whole blood IL-2 and IFN-gamma gene expression in normal dogs.

BACKGROUND: Pentoxifylline (PTX) is a methylxanthine phosphodiesterase inhibitor that is used as a hemorrheologic and anti-inflammatory agent in veterinary and human medicine. In human studies, PTX has been shown to decrease T-cell production of cytokines such as IL-2 and IFN-γ. A RT-qPCR assay to measure activated T-cell gene expression of IL-2 and IFN-γ has been validated in dogs. OBJECTIVES: The goal of this study was to utilize this assay to investigate the effects of PTX on in vitro cytokine gene expression in canine whole blood. METHODS: Whole blood from seven healthy dogs was collected and incubated with various concentrations of PTX for 1 hr before activation. PTX concentrations spanned and exceeded blood concentrations achieved when administered at clinically relevant dosages (1, 2, 10, 50 and 200 µg/ml). Cyclosporine was used at a concentration of 500 ng/ml as a positive control. All blood samples, including untreated activated baseline samples, were then activated with phorbol myristate acetate and ionomycin for 5 hrs. RESULTS: Analysis of activated whole blood by RT-qPCR revealed that there was not a significant suppression of IL-2 or IFN-γ gene expression at any concentration of PTX when evaluating ΔCt values. All samples exposed to cyclosporine showed significant changes from untreated activated baseline samples, demonstrating marked suppression as the positive control. Cytokine expression, presented as a percentage of untreated activated baseline samples, was also evaluated. After exposure to the highest concentration of PTX (200 µg/ml), median percentage cytokine expression was suppressed to just below 50% of baseline values. This concentration, however, is much higher than blood concentrations reported to be achieved at standardly used pentoxifylline doses. CONCLUSIONS: PTX does not appear to significantly suppress T-cell cytokine production in samples from most dogs at clinically relevant drug concentrations. Further testing is needed to establish the full effects of PTX on the immune system in dogs.

Effects of cyclosporine and dexamethasone on canine T cell expression of interleukin-2 and interferon-gamma.

Cyclosporine and glucocorticoids are powerful immunosuppressive agents used to treat many inflammatory diseases in dogs. Cyclosporine inhibits calcineurin-dependent pathways of T cell activation and resultant T cell cytokine production, and glucocorticoids directly inhibit genes coding for cytokines. Little work has been done comparing the effects of these agents on T cell cytokine production in dogs. Our study measured T cell interleukin-2 (IL-2) and interferon-gamma (IFN-γ) production using flow cytometry and T cell IL-2 and IFN-γ gene expression using quantitative reverse transcription polymerase chain reaction (qRT-PCR) in activated canine T cells incubated with cyclosporine and dexamethasone in vitro. For flow cytometric assays, diluted whole blood was cultured for 7 h in the presence of cyclosporine (10, 100, 500, and 1000 ng/mL) or dexamethasone (10 ng/mL, 100 ng/mL, 1 µg/mL, and 10 µg/mL). For qRT-PCR, whole blood was cultured for 5 h with the same drugs at the same concentrations, and RNA was then extracted from leukocytes. Flow cytometry and qRT-PCR both demonstrated inhibition of IL-2 and IFN-γ that was concentration-dependent in response to cyclosporine, and was more variable for dexamethasone. Quantitative RT-PCR but not flow cytometry documented significant reduction of IL-2 expression after dexamethasone treatment, while both methods showed concentration-dependent suppression of IFN-γ. Quantitative RT-PCR also revealed additional cytokine suppression at higher cyclosporine concentrations, an effect not found using flow cytometry, and may therefore be the preferred method for cytokine determination in dogs. Suppression of IL-2 and IFN-γ in activated T cells may have potential as an indicator of the efficacy of cyclosporine and glucocorticoids in suppressing canine T cell function in vivo, and may therefore be of value for characterizing the immunosuppression induced by these drugs in clinical patients.

Usage patterns of carbapenem antimicrobials in dogs and cats at a veterinary tertiary care hospital.

BACKGROUND: Carbapenems are a class of antimicrobials reserved for resistant infections or systemically ill people, yet the extent and context in which they are prescribed in the small animals is understudied. HYPOTHESIS/OBJECTIVE: To describe cases in dogs and cats treated with carbapenems to establish baseline data regarding the types of infections, outcomes, and resistance profiles of target infections. We hypothesize that prescribing practices for carbapenems at a veterinary tertiary care hospital would not comply with the recommended use guidelines in human medicine. METHODS: Retrospective study of veterinary medical records from all dogs and cats prescribed carbapenems between May 1, 2016, and April 30, 2017. RESULTS: A total of 81 infections (71 in dogs and 10 in cats) representing 68 animals (58 dogs and 10 cats) involving carbapenem use were identified. Cultures were performed in 65/81 (80%) infections, and antimicrobial use was de-escalated or discontinued in 10/81 (12%) infections. The average duration of treatment was 27.5 days and ranged from 1 to 196 days. Resistance to more than 3 antimicrobial classes was present in 57/115 (50%) isolates. Resistance to carbapenems was found in 2/64 (3%) of the bacterial isolates with reported carbapenem susceptibility. CONCLUSIONS AND CLINICAL IMPORTANCE: The majority of carbapenem use at a veterinary tertiary care hospital was prescribed in conjunction with culture and sensitivity determination, with de-escalation performed in a minority of cases, and treatment durations longer than typically recommended in human medicine.

Alterations in activated T-cell cytokine expression in healthy dogs over the initial 7 days of twice daily dosing with oral cyclosporine.

Cyclosporine is a powerful T-cell inhibitor used in the treatment of immune-mediated and inflammatory diseases in the dog. There is limited information on how to best monitor patients on cyclosporine therapy. Currently, pharmacokinetic and pharmacodynamic assays are available. Pharmacokinetic assays that measure the concentration of cyclosporine in the blood are used to assess if an appropriate drug concentration has been achieved; however, target blood drug concentrations have not been shown to reliably correlate with suppression of T-cell function in the dog. In human transplant recipients, therapeutic drug monitoring has shifted to include pharmacodynamic-based monitoring. Our laboratory has validated a RT-qPCR assay to measure the pharmacodynamic effects of cyclosporine in the dog. In this study, activated T-cell expression of IL-2 and IFN-γ was measured using RT-qPCR daily for 7 consecutive days in 8 healthy Walker hounds receiving oral cyclosporine at a dosage of 10 mg/kg every 12 hr. Cytokine production was found to be markedly decreased within 24 hr after the initiation of cyclosporine and remained significantly decreased for the duration of the project. Based on these results, cyclosporine causes a rapid drop in T-cell cytokine production that is sustained with continued dosing in healthy dogs. Although performed in healthy dogs, this study demonstrated a marked decrease in cytokine suppression within 24 hr of drug administration, suggesting that pharmacodynamic monitoring of cyclosporine's effects on T cells could be considered within several days of commencing therapy in dogs suffering from life-threatening immune-mediated disorders.

ACVIM consensus statement on the treatment of immune-mediated hemolytic anemia in dogs.

Immune-mediated hemolytic anemia (IMHA) causes severe anemia in dogs and is associated with considerable morbidity and mortality. Treatment with various immunosuppressive and antithrombotic drugs has been described anecdotally and in previous studies, but little consensus exists among veterinarians as to the optimal regimen to employ and maintain after diagnosis of the disease. To address this inconsistency and provide evidence-based guidelines for treatment of IMHA in dogs, we identified and extracted data from studies published in the veterinary literature. We developed a novel tool for evaluation of evidence quality, using it to assess study design, diagnostic criteria, explanation of treatment regimens, and validity of statistical methods. In combination with our clinical experience and comparable guidelines for humans afflicted with autoimmune hemolytic anemia, we used the conclusions of this process to make a set of clinical recommendations regarding treatment of IMHA in dogs, which we refined subsequently by conducting several iterations of Delphi review. Additionally, we considered emerging treatments for IMHA in dogs and highlighted areas deserving of future research. Comments were solicited from several professional bodies to maximize clinical applicability before the recommendations were submitted for publication. The resulting document is intended to provide clinical guidelines for management of IMHA in dogs. These guidelines should be implemented pragmatically, with consideration of animal, owner, and veterinary factors that may vary among cases.

ACVIM consensus statement on the diagnosis of immune-mediated hemolytic anemia in dogs and cats.

Immune-mediated hemolytic anemia (IMHA) is an important cause of morbidity and mortality in dogs. IMHA also occurs in cats, although less commonly. IMHA is considered secondary when it can be attributed to an underlying disease, and as primary (idiopathic) if no cause is found. Eliminating diseases that cause IMHA may attenuate or stop immune-mediated erythrocyte destruction, and adverse consequences of long-term immunosuppressive treatment can be avoided. Infections, cancer, drugs, vaccines, and inflammatory processes may be underlying causes of IMHA. Evidence for these comorbidities has not been systematically evaluated, rendering evidence-based decisions difficult. We identified and extracted data from studies published in the veterinary literature and developed a novel tool for evaluation of evidence quality, using it to assess study design, diagnostic criteria for IMHA, comorbidities, and causality. Succinct evidence summary statements were written, along with screening recommendations. Statements were refined by conducting 3 iterations of Delphi review with panel and task force members. Commentary was solicited from several professional bodies to maximize clinical applicability before the recommendations were submitted. The resulting document is intended to provide clinical guidelines for diagnosis of, and underlying disease screening for, IMHA in dogs and cats. These should be implemented with consideration of animal, owner, and geographical factors.