Prognostic factors and long-term outcome in dogs diagnosed with primary and secondary immune thrombocytopenia in Ireland

OBJECTIVES

The objectives of this study were to describe the outcome and prognostic factors in dogs diagnosed with primary and secondary immune thrombocytopenia (ITP).

MATERIALS AND METHODS

Medical records of dogs diagnosed with primary and secondary ITP in a referral hospital in Ireland were retrospectively evaluated. Short- and long-term survivals were analysed using Cox proportional-hazards regression models.

RESULTS

Medical records from 49 dogs were included. Primary and secondary ITP were diagnosed in 81.25% and 18.75% of dogs, respectively. The survival rate was 69% at 2 weeks (95% confidence interval [CI]: 0.54 to 0.80), 63% at 3 months (95% CI: 0.48 to 0.75) and 51% at 2 years (95% CI: 0.37 to 0.65). The overall median survival time was 985 days (primary ITP only: 1084 days; secondary ITP only: 225 days). Dogs surviving 30 days post-diagnosis had a median long-term survival time of 10 years. A lower haematocrit was negatively associated with survival [hazard ratio (HR) 0.96, 95% CI: 0.92 to 0.99]. Neutrophilia (HR: 0.44, 95% CI: 0.20 to 0.96) was associated with a 66% decreased risk of death. Band neutrophilia was associated with shorter hospitalisation (regression coefficient -3.56, 95% CI: -5.70 to -1.42). Presence of petechiae and ecchymoses (regression coefficient 2.41, 95% CI: 0.41 to 4.42), and the use of a second-line immunosuppressive agent (SLI) (regression coefficient 2.11, 95% CI: 0.11 to 4.12) were significantly associated with longer hospitalisation but not with survival.

CLINICAL SIGNIFICANCE

A lower haematocrit was the only variable associated with a worse prognosis in dogs diagnosed with ITP. Dogs with confirmed secondary ITP had an overall shorter median survival time. Dogs surviving over 30 days had an excellent prognosis.

Retrospective evaluation of the short-term response of human intravenous immunoglobulin therapy in the management of canine immune-mediated thrombocytopenia (2010-2015): 27 cases

OBJECTIVE

To describe the short-term response, early prognostic markers, and survival after treatment of canine immune-mediated thrombocytopenia (ITP) with human intravenous immunoglobulin (hIVIG) and methylprednisolone.

DESIGN

Retrospective cohort study.

SETTINGS

Private referral veterinary medical center.

ANIMALS

Twenty-seven client-owned dogs with primary or secondary ITP.

INTERVENTIONS

All dogs received 2 mg/kg IV methylprednisolone once daily and a single infusion of 5% hIVIG administered over 6-12 hours.

MEASUREMENTS AND MAIN RESULTS

A substantial increase in platelet count within 60 ± 12 hours post-hIVIG infusion (T60) was observed in 19 of the 27 (70%) dogs with ITP (responders). Thirty-four variables, including serum immunoglobulin (Ig) G concentration 24 ± 12 hours post-hIVIG infusion (T24IgG) and increase in serum IgG concentration 24 ± 12 hours post-hIVIG infusion (T24ΔIgG), were compared between responders and nonresponders at 5 different time points. Mortality rates of responders and nonresponders were evaluated 14 days post-hIVIG infusion. Serum T24IgG and serum T24ΔIgG were both significantly higher at T60 in responders. All responders were alive 14 days post-hIVIG infusion, and their mortality rate was significantly lower compared with nonresponders.

CONCLUSIONS

Responder dogs had an excellent 14-day survival rate. Serum T24IgG and serum T24ΔIgG concentrations accurately predicted response status at 60 hours post-hIVIG infusion.

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.

The effects of food on the pharmacokinetics of mycophenolate mofetil in healthy horses

Additional immunomodulatory treatment is needed for the management of immune-mediated disease in horses. Mycophenolate mofetil (MMF) is an immunomodulatory agent used in human and veterinary medicine for the prevention of graft rejection and the management of autoimmune diseases. Few studies exist investigating the pharmacokinetics of MMF in horses. The aim of this study was to evaluate the pharmacokinetics of a single dose of MMF in healthy horses in the fed vs. fasted state. Six healthy Standardbred mares were administered MMF 10 mg/kg by a nasogastric (NG) tube in a fed and fasted state. A six-day washout period was performed between the two doses. No statistically significant differences in mycophenolic acid (MPA) concentrations were seen at any time point apart from 8 h, when plasma metabolite concentrations were significantly higher in the fasted state compared to the fed state (p = .038). Evidence of enterohepatic recirculation was seen only in the fasted state; this did not yield clinical differences in horses administered a single-dose administration but may be significant in horses receiving long-term MMF treatment.

Romiplostim for treatment of thrombocytopenia in dogs: A retrospective assessment and clinical outcomes

BACKGROUND

Romiplostim, a thrombopoietin analog, is commonly used to treat immune-mediated thrombocytopenia (ITP) in humans, but its use in dogs remains limited.

OBJECTIVES

Evaluate the effects and adverse events of romiplostim administration in dogs with thrombocytopenia caused by various underlying diseases.

ANIMALS

Forty-two client-owned dogs with naturally occurring thrombocytopenia at 2 referral animal hospitals.

METHODS

Retrospective, multi-institutional analysis to evaluate the outcomes of romiplostim treatment in dogs.

RESULTS

Among the dogs treated with romiplostim, 27 experienced an increase in platelet count and 26 maintained a platelet count within the reference range. Platelet count improvement was observed in various conditions: primary ITP (90%, n = 18/20), pancytopenia of unknown etiology (42.9%, n = 3/7), chemotherapy-induced thrombocytopenia (50%, n = 3/6), babesiosis (100%, n = 1/1), radiotherapy-induced thrombocytopenia (0%, n = 0/1), and disseminated intravascular coagulopathy (33.3%, n = 2/6). The median time for platelet recovery (>50 000/μL) after romiplostim administration was 4 days, and the median time for platelet count normalization was 7 days. Median hospitalization time for the improvement group (I) was 5 days. The survival-to-discharge rates were 85%, 40%, and 28.6% for dogs with primary ITP, secondary thrombocytopenia, and thrombocytopenia of unknown etiology, respectively.

CONCLUSIONS AND CLINICAL IMPORTANCE

Romiplostim is a well-tolerated and promising treatment for primary ITP in dogs, suggesting its potential as a valuable therapeutic option for dogs with thrombocytopenia caused by various underlying conditions. These findings emphasize the need for further research to optimize romiplostim dosing and understand its role in treating secondary thrombocytopenia and pancytopenia of unknown etiology.

Retrospective evaluation of leflunomide as an adjunctive therapy in dogs with non-associative immune-mediated thrombocytopenia: 20 cases (2008-2021)

OBJECTIVE

To describe leflunomide as an adjunctive therapy in the treatment of non-associative immune-mediated thrombocytopenia.

MATERIALS AND METHODS

A retrospective study of dogs with a diagnosis of non-associative immune-mediated thrombocytopenia treated with leflunomide March 2008 to September 2021 was conducted. Data collected included signalment, clinical signs, physical examination findings and diagnostic testing performed. Medications administered, duration of hospital stay, time to platelet concentration >150×109/L and adverse events during leflunomide therapy were recorded. Relapses within a year of diagnosis were reported.

RESULTS

A total of 20 client-owned dogs met inclusion criteria. Nineteen of 20 dogs (95%) achieved a platelet concentration >150×109/L with leflunomide and prednisone combination therapy and four dogs (21.1%) relapsed during treatment or shortly after treatment. Adverse effects included diarrhoea (n=5), mild lymphopenia (n=9) and mild intermittent anaemia (n=1). A single dog developed hepatotoxicity presumed to be secondary to leflunomide therapy that resolved after drug discontinuation. One dog was treated for aspiration pneumonia during treatment. Two dogs were euthanased while receiving leflunomide.

CLINICAL SIGNIFICANCE

Length of hospitalisation, time to platelet recovery, treatment response and relapse rate were comparable with alternative treatment protocols. Most adverse effects did not require leflunomide dose adjustment; however, two dogs died while undergoing leflunomide treatment and there is compelling evidence that one of these dogs experienced fatal infection secondary to immune-suppression. Hepatotoxicity remains a known complication of leflunomide treatment and serial biochemistry testing is recommended.

Pharmacokinetics and tolerability of multiple-day oral dosing of mycophenolate mofetil in healthy horses

BACKGROUND

Additional efficacious immunomodulatory treatment is needed for the management of immune-mediated disease in horses. Mycophenolate mofetil (MMF) is an immunosuppressive drug that warrants assessment as a viable therapeutic agent for horses.

HYPOTHESIS/OBJECTIVES

To evaluate the pharmacokinetics (PK) of multiple-day oral dosing of MMF in healthy horses and to determine the tolerability of this dosing regimen.

ANIMALS

Six healthy Standardbred mares.

METHODS

Horses received MMF 10 mg/kg PO q12h for 7 days in the fed state. Serial sampling was performed over 12 hours on Days 1 and 7 with trough samples collected every 24 hours, immediately before morning drug administration. Noncompartmental PK analyses were performed to determine primary PK parameters, followed by calculation of geometric means and coefficients of variation. A CBC, serum biochemical profile, physical examination, and fecal scoring were used to assess dose tolerability.

RESULTS

Seven days of treatment resulted in a mycophenolic acid (MPA) area under the curve (AUC0-12 ) of 12 594 h × ng/mL (8567-19 488 h × ng/mL) and terminal half-life (T1/2 ) of 11.3 hours (7.5-15.9 hours), yielding minor metabolite accumulation in all horses treated. Salmonellosis was detected in the feces of 2 horses by Day 7, and all horses developed myelosuppression, hyperbilirubinemia, hyporexia, decreased gastrointestinal motility, and decreased fecal output by the seventh day of treatment.

CONCLUSION AND CLINICAL IMPORTANCE

Administration of MMF at 10 mg/kg PO q12h resulted in hematologic and clinical toxicity within 1 week of treatment. A decreased MMF dose, frequency, or both is needed to avoid colic. Drug monitoring should include frequent hemograms, serum biochemical profiles, and strict biosecurity protocols.

Successful Treatment With Prednisolone and Mycophenolate Mofetil in a Dog With Recurrent Erythema Multiforme Minor

A 3-year-old neutered male miniature poodle dog was referred with a 19-month history of unresolved dermatological signs despite long-term treatment. On physical examination, the dog had severe multifocal erythematous non-blanching patches and scales in the ventral trunk. Dermatological examination revealed Malassezia infection. Considering the history, clinical signs, and degree of infection, the possibility of a drug eruption appeared higher than that of Malassezia dermatitis. Therefore, bathing in lukewarm water was performed for 4 weeks without any other treatment, but there was no improvement. Subsequently, treatment for Malassezia dermatitis and differentiation from allergic dermatitis were performed, but there was still no improvement. A biopsy was performed, with the histopathology revealing lymphocytic interface dermatitis with keratinocyte apoptosis. Based on the histopathologic evaluation and clinical signs, the dog was diagnosed with erythema multiforme (EM) minor. Immunosuppressive therapy with prednisolone (1 mg/kg PO, twice daily) was initiated and had a good therapeutic effect. However, the lesion recurred after tapering the prednisolone dose (0.5 mg/kg PO, every other day). Therefore, steroid-sparing agents were added to the prednisolone regimen. Ciclosporin, azathioprine, and human intravenous immunoglobulin were administered in combination with prednisolone. Yet again, the lesion recurred when the dose of prednisolone was tapered to 0.5 mg/kg once daily. Mycophenolate mofetil (20 mg/kg PO, twice daily) was then added to the immunosuppressive regimen as a steroid-sparing agent, and complete remission was achieved and maintained even when the dose of prednisolone was tapered to 0.5 mg/kg every other day. This is the first reported case of recurrent EM successfully treated with a combination of prednisolone and mycophenolate mofetil, and this treatment option should be considered for recurrent EM.

Clinical and Clinicopathologic Discriminators Between Canine Acute Monocytic Ehrlichiosis and Primary Immune Thrombocytopenia

Acute canine monocytic ehrlichiosis due to Ehrlichia canis (aCME), and primary immune thrombocytopenia (pITP) are major differentials for dogs presented with thrombocytopenia, and the two diseases may clinically overlap. The aim of this study was to compare dogs diagnosed with naturally occurring aCME and pITP, to establish potentially useful clinical and clinicopathologic discriminators. A clinical record-based retrospective study was performed in 35 dogs diagnosed with aCME and 29 dogs with pITP. Dogs with aCME were significantly younger, and were more likely to experience depression or lethargy, anorexia, body weight loss, fever, lymphadenomegaly, tick infestation, and ocular discharge on admission, compared to dogs with pITP. In contrast, dogs with pITP presented more frequently with overt bleeding and had a significantly higher bleeding score compared to dogs with aCME. Dogs with aCME were more likely to be anemic and hypoalbuminemic on presentation compared to dogs with pITP. Dogs with pITP had higher white blood cell and neutrophil counts as well as lower platelet counts than dogs with aCME and were more likely to present with leukocytosis, neutrophilia and monocytosis. These clinical, hematological, and biochemical findings may be helpful discriminators between aCME and pITP, on the understanding that they will be interpreted in the context of disease-specific testing.

Noncompartmental pharmacokinetics of three intravenous mycophenolate mofetil concentrations in healthy Standardbred mares

BACKGROUND

Mycophenolate mofetil (MMF) is the prodrug of mycophenolic acid (MPA) which acts as an immunosuppressive agent. During the biotransformation of MMF to MPA, additional metabolites including MPA phenol glucuronide (MPAG), MPA acyl glucuronide (AcMPAG) and MPA phenol glucoside (MPG) are formed.

OBJECTIVE

To define the noncompartmental pharmacokinetic (PK) parameters of three single doses of intravenous (i.v.) MMF and its downstream metabolites in healthy horses.

ANIMALS

Six healthy Standardbred mares.

MATERIALS AND METHODS

Generic MMF (Par Pharmaceuticals; Chestnut Ridge, NY, USA) was reconstituted and administered as a single i.v. bolus at 1.0 mg/kg, 5.0 mg/kg and 10.0 mg/kg with an eight day washout between treatments. Blood samples were collected immediately before MMF administration and over 24 h. A liquid chromatography-tandem mass spectrometry assay was developed following FDA guidance to determine plasma MMF, MPA, MPAG, AcMPAG and MPG concentrations. Plasma concentrations were analysed independently, followed by calculation of geometric mean and coefficient of variation.

RESULTS

Noncompartmental PK parameters were determined for MMF and all metabolites at all doses. MMF was rapidly converted to MPA in all horses. Each incremental dose of MMF resulted in increases in C_max and AUC_inf _obs for MPA and the three additional metabolites. Within the 10-fold dose range, the increase in C_max and AUC_inf _obs for MMF and its metabolites was nonlinear.

CONCLUSIONS AND CLINICAL RELEVANCE

Horses biotransform MMF into MPA, MPAG, AcMPAG and MPG via the glucuronidation and glucosidation clearance pathways. Equine reference PK profiles for MPA and the metabolites, MPAG, AcMPAG and MPG were established.

Splenectomy in the management of primary immune-mediated hemolytic anemia and primary immune-mediated thrombocytopenia in dogs

Background

Current reports about the use of splenectomy for the management of immune‐mediated hemolytic anemia (IMHA) or immune‐mediated thrombocytopenia (ITP) or both in dogs are limited.

Objectives

To retrospectively describe the use of splenectomy as part of the management for IMHA, ITP, and concurrent IMHA and severe thrombocytopenia (CIST) in dogs. It was hypothesized that splenectomy would be beneficial in allowing for reduction of dose of immunosuppressive drugs or discontinuation in 1 or more of these groups.

Animals

Seventeen client‐owned dogs (7 with IMHA, 7 with ITP, and 3 with CIST) were identified across 7 UK‐based referral hospitals from a study period of 2005 to 2016.

Methods

Data were collected retrospectively via questionnaires and included information about diagnosis, management and treatment response before and after splenectomy. Based on clinical outcome, treatment with splenectomy as part of the management protocol was classified as either successful or unsuccessful.

Results

Six of 7 dogs with ITP were managed successfully with splenectomy as part of their management protocol (3 complete and 3 partial responses), although 1 subsequently developed suspected IMHA. Of the 7 dogs with IMHA, splenectomy was part of a successful management protocol in 4 dogs (2 complete and 2 partial responses). In the CIST group, 1 case (1/3) responded completely to management with splenectomy as part of the management protocol.

Conclusions and Clinical Importance

Splenectomy was considered successful and well tolerated in most cases of isolated ITP. Whether there is a benefit of splenectomy in cases of IMHA and CIST could not be determined in the current study.

Immunomodulatory and immunosuppressive drug protocols in the treatment of canine primary immune thrombocytopenia, a scoping review

Primary immune thrombocytopenia (ITP) is a cause of severe thrombocytopenia in dogs. Immunosuppressive corticosteroid drugs are frequently used in the management of ITP, but treatment failure may occur. Immunomodulatory and non-corticosteroid immunosuppressive drugs might improve outcomes from therapy either alone or in combination with corticosteroids. The objectives of this scoping review were (1) to evaluate the current evidence relating to immunomodulatory and immunosuppressive drug protocols in the treatment of canine ITP, and (2) to answer the clinical question, whether or not therapy with immunomodulatory or non-corticosteroid immunosuppressive drugs alone or in combination with corticosteroids could improve outcome, compared to therapy with corticosteroids alone. A literature search was performed in the electronic databases of Agricola, CAB Abstracts, Embase, Medline and Web of Science for publications in November 2019 and again February 1, 2021. Selection criteria were relatively strict and included peer-reviewed research papers reporting outcome measures from immunomodulatory and immunosuppressive drug protocols in the treatment of canine ITP with a pre-therapeutic mean or median platelet count < 50,000/µL as a strict criterion for inclusion. Studies were evaluated if they had an appropriate diagnostic work up to exclude underlying conditions. Outcome measures and adverse events were compared between drug protocols both within studies and between studies. The search identified 456 studies, with six studies being eligible for inclusion. The studies were mostly case series while two were randomized controlled trials. Level of evidence varied with an overall uncertain subject enrollment, small groups, inadequate description and variable use of drug protocols or outcome measures. For outcomes such as platelet recovery time and duration of hospitalization, an improvement was observed using adjunctive therapy (human intravenous immunoglobulin) compared to therapy with corticosteroids alone. For outcomes of complete platelet recovery time, survival (6-month), mortality and relapse, no improvement was observed using adjunctive drugs compared to corticosteroids alone. Specifically, therapy with mycophenolate mofetil alone and adjunctive azathioprine were associated with more severe adverse events compared to other drug protocols. Evidence relating to immunomodulatory and immunosuppressive drug protocols in the treatment of canine ITP was of variable quality. Future larger case-controlled trials are required for determination of optimal treatment protocols in canine ITP.

The Effects of Mycophenolate on the Formation of Granulation Tissue Post-operatively in Canine Tracheal Stent Patients (2014-2020)

Objectives: To determine if mycophenolate mofetil reduces the incidence and severity of granulation tissue in-growth in canine tracheal stent patients. Study design: Randomized clinical trial. Animals: 111 dogs from the hospital population. Methods: Client-owned dogs that received an endoluminal self-expanding tracheal stent for canine tracheal collapse between 2014 and 2020 were randomly assigned into one of two treatment groups. Control group medication protocol consisted of prednisone 0.5 mg/kg PO BID/SID/EOD × 30 days, hydrocodone 0.25 mg/kg PO TID × 30 days, and cefovecin 8 mg/kg SQ post-placement. Mycophenolate group medication protocol was identical to the control group medication protocol with the addition of mycophenolate mofetil 10 mg/kg PO BID × 30 days, SID for life. Recheck tracheoscopy was performed at 1, 3, and 6 months post-stent placement. Presence and severity of granulation tissue were determined by tracheoscopy and were recorded as a percentage of tracheal lumen obstruction by blinded evaluators (none present, <25%, >25-50%, and >50%). Results: At none of the three time points was there a statistically significant difference in grade between controls and those receiving mycophenolate (p = 0.467, p = 0.330, and p = 0.410). Conclusions and Clinical Significance: Our results suggest that mycophenolate can be safely given to these patients but do not support that its administration will reduce the incidence and severity of granulation tissue. Although a difference was observed in the severity of granulation tissue between the two groups, loss to follow-up may have influenced conclusions. A larger study would be warranted to further evaluate the effect of mycophenolate on the development of granulation tissue.

A retrospective study of adverse effects of mycophenolate mofetil administration to dogs with immune-mediated disease

Background

Information regarding adverse events (AEs) of mycophenolate mofetil (MMF) is limited.

Objectives

To evaluate the types and frequency of potential AEs of MMF in dogs with immune‐mediated disease.

Animals

One hundred thirty‐one dogs treated with MMF for management of suspected immune‐mediated disease.

Methods

Retrospective study. Medical records were reviewed to find and group suspect AEs in gastrointestinal (GI), hematologic, and other categories. Age, dosage, body weight, and sex were analyzed between dogs with and without AEs by using the Mann‐Whitney U‐test and chi‐squared test.

Results

The median starting dosage of MMF was 17.5 mg/kg/day (interquartile range [IQR] = 15.1‐20.6 mg/kg/day) and the median treatment duration was 56 days (IQR = 14‐236 days). Mycophenolate mofetil was prescribed for immune‐mediated hemolytic anemia (n = 31), immune‐mediated thrombocytopenia (n = 31), pemphigus foliaceus (n = 15), immune‐mediated polyarthritis (n = 12), and others (n = 42). Overall, potential AEs of MMF were observed in 34 of 131 dogs (GI 24.4% [31/127], neutropenia 4% [3/76], anemia 4% [1/25], thrombocytopenia 4.0% [1/25], and dermatologic 1.5% [2/131]). There were no significant differences among dogs with (n = 37) or without potential AEs (n = 94) in regards to sex, age, body weight, or dosage of MMF (P = .06, .13, .24, and .26, respectively).

Conclusions and Clinical Importance

In the dogs administered MMF, GI AEs were most common. Since potential hematologic and dermatologic AEs developed in a few dogs, clinicians should be aware of these when prescribing MMF to dogs with immune‐mediated disease.

Pharmacokinetics of mycophenolate mofetil following single-dose intravenous and single- and multiple-dose oral administration and clinicopathologic effects of mycophenolate mofetil following long-term oral administration in healthy horses

OBJECTIVE

To characterize the pharmacokinetics of mycophenolate mofetil (MMF) following single-dose IV or PO administration, characterize the pharmacokinetics of MMF following long-term PO administration, and describe the clinicopathologic effects of long-term MMF administration in horses.

ANIMALS

12 healthy adult horses.

PROCEDURES

In phase 1, 6 horses received a single IV (2.5 mg/kg) or PO (5 mg/kg) dose of MMF in a randomized balanced crossover assessment (≥ 2-week interval between administrations). In phase 2, 6 other horses received MMF for 60 days (5 mg/kg, PO, q 24 h for 30 days and then 5 mg/kg, PO, q 48 h for an additional 30 days).

RESULTS

Following IV (single-dose) or PO (single- or multiple-dose) administration, MMF was rapidly converted to mycophenolic acid. For single-dose PO administration, mean ± SD maximum plasma mycophenolic acid concentration was 1,778.3 ± 441.5 ng/mL at 0.71 ± 0.29 hours. For single-dose IV administration, mean systemic clearance and volume of distribution at steady state were 0.689 ± 0.194 L/h/kg and 1.57 ± 0.626 L/kg, respectively. Following single doses, mean terminal half-life was 3.99 ± 0.865 hours for IV administration and 4.02 ± 1.01 hours for PO administration. The accumulation index following long-term PO administration was 1.0 ± 0.002, and the terminal half-life was 4.59 ± 1.25 hours following the final dose on day 60. None of the horses developed abnormal clinical signs or had any consistently abnormal clinicopathologic findings.

CONCLUSIONS AND CLINICAL RELEVANCE

Further investigation of the clinical efficacy of long-term MMF treatment of horses with autoimmune diseases is warranted.

Romiplostim as Adjunctive Treatment of Refractory Amegakaryocytic Immune Thrombocytopenia in a Dog

A 9-year-old, intact male, mixed-breed dog was admitted with a 3-day history of severe thrombocytopenia and bleeding diathesis. Physical examination revealed mucosal and cutaneous petechiae and ecchymoses, melena, and gross hematuria. Clinicopathologic evaluation indicated severe thrombocytopenia, anemia, and panhypoproteinemia. Serology for common endemic vector-borne pathogens was negative and thoracic and abdominal imaging was unremarkable. Bone marrow aspiration cytology revealed aplasia of the megakaryocytic lineage, in the context of a mildly hypoplastic myeloid and a normal erythroid series. A diagnosis of presumptive primary amegakaryocytic immune thrombocytopenia (ITP) was established. Treatment with vincristine, prednisolone, and mycophenolate mofetil along with several whole blood transfusions failed to achieve clinical and clinicopathologic remission. As an adjunct treatment, romiplostim was administered at a cumulative dose of 15 μg/kg, subcutaneously, in 2 sessions, 1 week apart, and complete clinical and hematological remission was noted 8 days postinitiation of romiplostim. Thirty-eight months later, the dog remains clinically healthy with no evidence of hematological relapse. Romiplostim could be a promising adjunctive treatment option in dogs with refractory ITP.

Lyophilized platelets versus cryopreserved platelets for management of bleeding in thrombocytopenic dogs: A multicenter randomized clinical trial

Background

Thrombocytopenia in dogs is common in critical care medicine, but availability of fresh platelet concentrates in veterinary medicine can be limiting. Lyophilized platelets have long shelf‐lives and can be easily transported, stored, and administered in various settings.

Objective

To evaluate the efficacy and safety of a novel trehalose‐stabilized canine lyophilized platelet product in thrombocytopenic dogs with clinically‐evident bleeding.

Animals

Eighty‐eight dogs with platelet counts <50 × 10³/μL and a standardized bleeding assessment tool (DOGiBAT) score ≥2.

Methods

Multicenter, randomized, non‐blinded, non‐inferiority clinical trial comparing dimethyl sulfoxide (DMSO)‐stabilized cryopreserved platelet concentrates (CPP) with trehalose‐stabilized lyophilized platelets (LP) for control of bleeding in thrombocytopenic dogs. Dogs were randomized to receive 3 × 10⁹ platelets/kg of LP or CPP. Primary outcome measures were change in DOGiBAT score, platelet count, need for additional red cell transfusion and all‐cause mortality.

Results

Fifty dogs received LP and 38 received CPP. Baseline demographics and clinical characteristics of both groups were comparable. At 1‐hour post‐transfusion, LP were superior for change in DOGiBAT score, and non‐inferior at 24‐hours post‐transfusion. The LP were non‐inferior to CPP for change in platelet count, need for additional red blood cell units, and survival to discharge. The LP were superior for change in hematocrit at 1‐hour post‐transfusion, and non‐inferior at 24‐hours. No adverse effects were noted in either group.

Conclusions and Clinical Importance

A novel trehalose‐stabilized canine LP product appears to be logistically superior and is clinically non‐inferior to DMSO‐stabilized canine CPP for management of bleeding in thrombocytopenic dogs.

Evaluating the use of cytosine arabinoside for treatment for recurrent canine steroid-responsive meningitis-arteritis

BACKGROUND

Relapses in steroid-responsive meningitis-arteritis (SRMA) are frequently observed but specific treatment protocols to address this problem are sparsely reported. Standard treatment includes prolonged administration of glucocorticoids as monotherapy or in combination with immunosuppressive drugs. The aim of this study was to assess the safety and efficacy of cytosine arabinoside (CA) in combination with glucocorticoids for treatment of SRMA relapses in 12 dogs on a retrospective basis.

METHODS

Dogs with recurrent episodes of SRMA and treated with a combination of CA and prednisolone were included. Information about clinical course, treatment response and adverse events was collected from medical records. Ethical approval was not required for this study.

RESULTS

Ten dogs (10/12) responded well to the treatment with clinical signs being completely controlled. One dog is in clinical remission, but still under treatment. One dog (8%) showed further relapse. Mean treatment period was 51 weeks. Adverse events of variable severity (grade 1-4/5) were documented in all dogs during treatment according to the veterinary cooperative oncology group grading. Three dogs developed severe adverse events. Laboratory findings showed marked changes up to grade 4. Diarrhoea and anaemia were the most often observed adverse events (6), followed by dermatitis (4), alopecia (3) and pneumonia (3). Including blood chemistry changes (13), 50 adverse events were found in total.

CONCLUSION

Treatment with CA and glucocorticoids resulted in clinical remission in 10/12 dogs, but a high incidence of adverse events occurred requiring additional measures. All adverse events could be managed successfully in all cases.

Application of therapeutic plasma exchange in dogs with immune-mediated thrombocytopenia

Therapeutic plasma exchange (TPE) is an emerging treatment for dogs with immune-mediated diseases, but reports for treatment of immune-mediated thrombocytopenia (IMT) are lacking. These case reports illustrate the application of centrifugal TPE in 4 dogs with IMT. All dogs presented with severe hemorrhage requiring ≥1 blood transfusions, were unresponsive to conventional treatment or both. Dogs were treated with 3 sequential centrifugal TPE sessions, totaling 4.0 to 4.9 total plasma volumes exchanged per dog. In 3 dogs, TPE was associated with improvement in clinical manifestations of bleeding and platelet count in combination with immunosuppressive drugs. One dog was euthanized after 3 treatments because of persistent severe thrombocytopenia and hemorrhage. Preliminary observations indicate that TPE is safe and may be a useful adjunct in the management of IMT that is severe or refractory to traditional treatment.

Suspected hepatopathy and pancreatitis associated with mycophenolate mofetil use in a cat with immune-mediated haemolytic anaemia

Case summary

A 5-year-old spayed female domestic shorthair cat was referred for severe anaemia. Findings on initial work-up were consistent with a diagnosis of idiopathic immune-mediated haemolytic anaemia. A combination of prednisolone and mycophenolate mofetil (MMF) was instituted. On revisit approximately 2 months later, red blood cell parameters were normal, but the plasma was described as icteric, prompting further investigation. Concurrent hepatopathy and pancreatitis were diagnosed, suspected as being adverse reactions to MMF, as has been reported with use of the drug in humans. Resolution of serum biochemistry abnormalities took approximately 2 months, following discontinuing MMF. At the time of writing, the cat remained clinically well 1 year after initial presentation.

Relevance and novel information

With increasing use of MMF as an immunosuppressive agent in cats, clinicians should be aware of both common and potentially rare adverse effects, such as those described herein. In addition, suitable monitoring tools need to be in place to facilitate early detection and appropriate management.

"Acute onset tetraplegia associated with immune-mediated thrombocytopenia and suspected secondary intraspinal hemorrhage in a dog"

Neurologic manifestations of immune-mediated thrombocytopenia are uncommon, and limited reports exist in human and veterinary medicine. This report documents acute onset of tetraplegia in a dog with immune-mediated thrombocytopenia and suspected secondary intraspinal hemorrhage with subsequent recovery of neurologic function following treatment.

Retrospective evaluation of cyclosporine in the treatment of presumed idiopathic chronic hepatitis in dogs

Background

The etiology of idiopathic chronic hepatitis (ICH) in dogs is poorly understood, but evidence supports an immune‐mediated pathogenesis in some dogs.

Objectives

To describe a case series of dogs with presumed ICH treated with cyclosporine (CsA) with or without concurrent medications and to document the incidence of biochemical remission and factors associated with failure to attain remission.

Animals

Forty‐eight client‐owned dogs diagnosed with presumed ICH, treatment of which included CsA.

Methods

Two‐institution, retrospective case series of dogs between 2010 and 2017. All dogs were treated with CsA with or without concurrent medications for ≥2 weeks. Data were collected from medical records.

Results

Biochemical remission (<1.1 times the upper limit of normal for alanine aminotransferase activity) was attained in 79% of dogs (38/48). Median dose of CsA at remission was 7.9 mg/kg/d (range, 2.5‐12.7 mg/kg/d) and median time to remission was 2.5 months (range, 0.75‐18 months). Concurrent hepatoprotectant treatment was not associated with likelihood of remission. Clinical score, ascites, hypoalbuminemia, hyperbilirubinemia, prolonged coagulation times, dose, and duration of treatment were not associated with the probability of remission or time to remission. Common adverse effects of CsA were gastrointestinal signs in 38% (18/48) and gingival hyperplasia in 25% (12/48) of treated dogs.

Conclusion and Clinical Importance

A treatment regimen including CsA and frequent hepatoprotectant use resulted in biochemical remission of ICH in most dogs. None of the evaluated factors, including hepatoprotectant use, were significantly associated with likelihood of remission. Future prospective studies are indicated to evaluate CsA monotherapy in ICH dogs.

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.

Mycophenolic acid in patients with immune-mediated inflammatory diseases: From humans to dogs

Mycophenolic acid (MPA), a noncompetitive, selective and reversible inhibitor of inosine 5'-monophosphate dehydrogenase (IMPDH), is an immunosuppressive agent that has a long history in medicine. Mechanistically, the inhibition of IMPDH leads to the selective and eventual arrest of T- and B-lymphocyte proliferation. Mycophenolate mofetil (MMF), the first MPA-based product to receive marketing approval over two decades ago, was originally indicated for the prophylaxis of organ rejection in human transplant patients. Given its broad immunosuppressive properties and ability to selectively inhibit lymphocyte division and effector functions, the clinical utility of MPA was subsequently explored in a host of autoimmune diseases. Human clinical studies have shown MPA to be safe and effective and support its off-label administration for immune-mediated diseases such as lupus, myasthenia gravis and atopic dermatitis. MMF became generically available in the United States in 2008, and its clinical utility is increasingly being explored as a treatment option for dogs with immune-mediated diseases. This review summarizes the available literature for MPA pharmacokinetics and pharmacodynamics, and the current status of MPA as a treatment for client-owned dogs diagnosed with immune-mediated diseases.

Indolent, T-cell, large granular lymphocytic leukaemia in a dog presenting with severe neutropenia and an absence of lymphocytosis

In humans, large granular lymphocytic leukaemia (LGLL) is a low-grade, indolent lymphoproliferative disorder of large granular lymphocytes (LGL) associated with autoimmune disorders; including rheumatoid arthritis and single or multiple cytopenias; particularly neutropenia. Therapy largely centres around immunosuppression which aims to resolve the immune-mediated secondary pathology, often without eradicating the neoplastic clone. The most effective agents appear to be cyclophosphamide, cyclosporine and methotrexate. This case report describes the presentation, diagnostics, therapeutic approach and outcome of a 6 year-old Golden Retriever presenting with severe neutropenia. Chlorambucil, prednisolone and cyclosporine failed to improve the neutropenia but subsequent cyclophosphamide resulted in a sustained albeit temporary improvement in neutrophil count and the ability to withdraw prophylactic antibacterials. This case closely mirrors the diagnostics and therapeutic response in human LGLL.