A safety evaluation of allogeneic freeze-dried platelet-rich plasma or conditioned serum compared to autologous frozen products equivalents in equine healthy joints.

BACKGROUND: Hemoderivatives such as autologous conditioned serum (ACS) and platelet-rich plasma (PRP) have been used as potential disease-modifying therapies in musculoskeletal disorders such as osteoarthritis (OA). These therapies are based on the delivery of multiple growth factors and anti-inflammatory cytokines that are known to participate in inflammatory processes. The variability of cytokine content due to the autologous nature of the product, the non-availability for immediate use and need for storage at low temperatures are limitations for its use in the field. An allogeneic freeze-dried conditioned serum (CS) and PRP would provide field clinicians with a more practical approach to use such products in daily practice. Based on in vitro preliminary data, this experimental study aimed to test the in vivo safety of allogeneic freeze-dried CS and PRP in healthy joints, using the horse as a model. RESULTS: Eight horses were randomly assigned and treated with PRP or CS. Horses had three joints injected with ALLO-FD PRP or CS, and three contralateral joints injected with the AUTO version of the same product, by a blinded clinician. Horses were evaluated clinically, and had synovial fluid collected at different time points and evaluated for cell content, PGE2 and protein. Both CS and PRP products triggered a self-limiting and mild inflammatory response in equine healthy joints. This was indicated by the transient increase in nucleated cell count, PGE2 and total protein in synovial fluid. This mild inflammatory response did not result in significant lameness and was not different among the groups. CONCLUSIONS: The allogeneic freeze-dried PRP and CS showed to be overall safe and not dissimilar compared to their autologous frozen version in equine healthy joints. Further studies are necessary to evaluate the modulatory effects of these therapies in a clinical setting.

Iron, hepcidin, and microcytosis in canine hepatocellular carcinoma.

BACKGROUND: Erythrocyte microcytosis in some dogs with hepatocellular carcinoma (HCC) suggests a derangement in systemic iron. Hepcidin, the master regulator of iron, is secreted by the liver in response to interleukin 6 (IL-6) and/or bone morphogenetic protein 6 (BMP6) and can cause microcytosis. OBJECTIVES: Pilot study to compare the quantities of hepcidin, IL-6, and BMP6 RNA molecules in archival tumoral (HCC) and adjacent peritumoral (non-HCC) hepatic tissue to determine if they are different between tissue types or associated with microcytosis. METHODS: RNA was isolated from formalin-fixed, paraffin-embedded HCC and non-HCC tissue from seven microcytic dogs and four normocytic dogs. Digital RNA counts of hepcidin, IL-6, or BMP6, and six other iron-regulatory genes were determined using the Nanostring nCounter system. The area of blue on each section was digitally evaluated to measure the extent of Prussian blue staining objectively. Parameters were compared between HCC and non-HCC tissue and between microcytic and normocytic groups. RESULTS: Hepcidin was decreased, and transferrin receptor 1 (TfR1) was increased in HCC tissue compared with non-HCC tissue. Non-HCC hepcidin RNA counts correlated negatively with MCV and positively with the extent of iron staining. Hepcidin expression was higher in non-HCC tissue of microcytic cases than in normocytic cases. CONCLUSIONS: Canine HCC cases showed relatively increased iron staining in non-HCC tissue and decreased hepcidin RNA in HCC tissue. Microcytic cases had higher hepcidin RNA in non-HCC tissue than normocytic cases. Future studies may extend these findings to protein quantification, cellular localization of RNA changes, and determining if iron loading in canine liver is a predisposing factor for HCC.

Systemic administration of a pharmacologic iron chelator reduces cartilage lesion development in the Dunkin-Hartley model of primary osteoarthritis.

Iron has been emerging as a key contributor to aging-associated, chronic disorders due to the propensity for generating reactive oxygen species. To date, there are a limited number of publications exploring the role of iron in the pathogenesis of primary/age-related osteoarthritis (OA). The objective of this study was to determine whether reduced iron via pharmacologic iron chelation with deferoxamine (DFO) affected the development and/or severity of cartilage lesions in a primary OA model. At 12-weeks-of-age, 15 male Dunkin-Hartley guinea pigs received either 46 mg/kg DFO (n = 8) or vehicle control (n = 7) injected subcutaneously twice daily for five days each week. Movement changes, captured via overhead enclosure monitoring, were also determined. Termination occurred at 30-weeks-of-age. Iron was quantified in serum, urine, liver, and femoral head articular cartilage. Left knees were evaluated for: structural changes using histopathology guidelines; and immunohistochemistry. Gene expression analysis was conducted on right knee articular cartilage. DFO reduced iron levels in femoral head articular cartilage (p = 0.0006) and liver (p = 0.02), and increased iron within urine (p = 0.04) and serum (p = 0.0009). Mobility of control animals declined, while the DFO group maintained activity levels similar to the first month of treatment (p = 0.05). OA-associated cartilage lesions were reduced in knees of DFO animals (p = 0.0001), with chondrocyte hypocellularity a key histologic difference between groups (p < 0.0001). DFO-receiving animals had increased immunostaining for phosphorylated adenosine monophosphate activated protein kinase alpha within knee articular cartilage; lower transcript counts of several proapoptotic genes (p = 0.04-0.0004) and matrix-degrading enzymes (p = 0.02-<0.0001), and increased expression of the anti-apoptotic gene Bcl-2 (p < 0.0001) and a tissue inhibitor of matrix-metalloproteinases (p = 0.03) were also observed. These results suggest that iron chelation delayed the progression of primary OA in an animal model and could hold potential as a translational intervention. These findings provide expanded insight into factors that may contribute to the pathogenesis of primary OA.

Coagulation status, fibrinolysis, and platelet dynamics in dogs with chronic inflammatory enteropathy.

BACKGROUND: Coagulation status is poorly understood in dogs with chronic inflammatory enteropathy (CIE). Fibrinolytic activity and platelet dynamics have not been evaluated in CIE dogs. OBJECTIVES: To assess coagulation status and fibrinolysis in normoalbuminemic CIE dogs (CIE-N) and CIE dogs with protein-losing enteropathy (CIE-PLE) compared to healthy controls (HC). To evaluate thromboelastography (TEG) variable differences between groups and for correlations with clinicopathologic data. To report platelet dynamics in CIE dogs. ANIMALS: Twenty-five client-owned dogs with CIE (n = 16 CIE-N; n = 9 CIE-PLE); 14 HC beagle dogs. METHODS: All dogs had tissue factor + tissue plasminogen activator TEG. Nine of 25 CIE dogs had whole blood impedance platelet aggregometry. The TEG variables and coagulation data were compared between all CIE vs HC dogs, CIE-N dogs vs HC, and CIE-PLE dogs vs HC. Clinicopathologic and coagulation data were available for CIE dogs and assessed for correlation to TEG variables. RESULTS: Dogs with CIE had higher maximum amplitude (MA; P < .001), longer clot lysis times (CLTs; P < .001), lower % lysis after 30 minutes (LY30; P < .001), and % lysis after 60 minutes (LY60; P < .001) compared to HC, suggesting hypercoagulability and hypofibrinolysis. When separated out, both CIE-N and CIE-PLE dogs had higher MA, longer CLT, and lower LY30 and LY60 compared to HC. Serum albumin and 25-hydroxyvitamin D (25[OH]D) concentrations, and plasma antithrombin and fibrinogen concentrations moderately correlated with MA. CONCLUSIONS AND CLINICAL IMPORTANCE: Normoalbuminemic and hypoalbuminemic CIE dogs were considered hypercoagulable based on TEG compared to HC. Some CIE dogs displayed hypofibrinolytic phenotypes on TEG.

Variability in the cleavage of exosome-associated transferrin receptor questions the utility of clinically useful soluble transferrin receptor assays for dogs, cats, and horses.

Whole transferrin receptor (TfR) is present in reticulocyte exosomes. Soluble transferrin receptor (sTfR) is cleaved from whole TfR in human plasma, with the remnant cytoplasmic domain (cTfR) remaining membrane associated. In humans, sTfR is a biomarker that can detect iron deficiency in the presence of inflammatory disease. This condition is still a diagnostic dilemma in veterinary species. We aimed to (1) confirm the presence of exosomes and exosome-associated TfR in the serum of dogs, cats, and horses; and (2) to assess and compare the proportion of cTfR to total (cTfR + whole) in exosomal membranes of healthy and diseased dogs and cats and in healthy horses to indirectly predict their anticipated levels of circulating sTfR. We used discarded serum and whole blood samples from canine and feline patients, separated into healthy and diseased groups based on the health status of each patient, and healthy equine participants from a previous study. Ultracentrifugation, followed in some experiments by OptiPrep discontinuous density gradient fractionation, was used to isolate exosomes. Exosomes and associated TfR were identified using TEM and Western blot for TfR, respectively. Densitometry tracings of Western blots of serum exosomes were used to measure the proportion of cTfR to total TfR. Extracellular vesicles compatible with exosomes were successfully isolated and expressed TfR. The proportion of cTfR in dogs was greater than 50%, indicating that a majority of the whole TfR was cleaved to produce sTfR (and remnant cTfR). There was significant interindividual variation and no significant difference between healthy and diseased animals. The proportion of cTfR in cats was very low at 11%, indicating that very little sTfR was likely produced. There was a small yet significant difference between healthy and diseased cats. Healthy horses do not appear to cleave exosome-associated TfR. Diagnosis of iron deficiency in the presence of inflammatory disease remains a challenge in veterinary medicine. Our results indicate that TfR is poorly or unpredictably cleaved in veterinary species, revealing that there are species differences in exosomal TfR handling. These data suggest that development of an assay for the detection and quantification of sTfR in the species investigated may not be warranted.

Platelet-Rich Products and Their Application to Osteoarthritis.

Autologous platelet-rich plasma (PRP) is a biological preparation made from the patient's own plasma that contains a platelet concentration above the whole blood baseline. Owing to the release of growth factors and other cytokines after degranulation, platelets have a central role in inflammation and in different stages of the healing process. For this reason, PRP-derived products have been used to enhance healing of musculoskeletal injuries and modulate progression of inflammatory processes, including osteoarthritis (OA). Osteoarthritis is one of the main causes of musculoskeletal disabilities in horses, and currently, there is no effective treatment for this disease. Treatments that focus on the modulation of inflammation and disease progression offer new hope for OA. Platelet-rich plasma provides a more practical and accessible option of therapy compared to other forms of biological treatment (i.e., stem cell therapies) and is believed to induce the production of functional matrix. However, several factors related to PRP production, including methods of preparation and application, and intraindividual variability, lead to an inconsistent product, precluding reliable conclusions about its efficacy for clinical use. The aim of this study was to review the benefits related to the clinical use of PRP in OA as well as factors that influence its use, the limitations of this treatment, and future directions of PRP research and therapy.

Virtual Microscopy Is More Effective Than Conventional Microscopy for Teaching Cytology to Veterinary Students: A Randomized Controlled Trial.

Virtual microscopy (VM) using scanned slides and imaging software is increasingly used in medical curricula alongside instruction in conventional microscopy (CM). Limited reports suggest that VM is useful in the veterinary education setting, and generally well-received by students. Whether students can apply knowledge gained through VM to practical use is unknown. Our objective was to determine whether instruction using VM, compared to CM, is a successful method of training veterinary students for the application of cytology in practice (i.e., using light microscopes). Seventy-one veterinary students from Colorado State University who attended a voluntary 3-hour cytology workshop were randomized to receive the same instruction with either VM (n = 35) or CM (n = 36). We compared these students to a control group (n = 22) of students who did not attend a workshop. All students took a post-workshop assessment involving the interpretation of four cases on glass slides with CM, designed to simulate the use of cytology in general practice. Students also took an 18-question survey related to the effectiveness of the workshop, providing their opinions on cytology instruction in the curriculum and their learning preference (VM or CM). The mean assessment score of the VM group (14.18 points) was significantly higher than the control group (11.33 points, p = .003), whereas the mean of the CM group (12.77 points) was not statistically significantly different from controls (p = .170). Not only is VM an effective method of teaching cytology to veterinary students that can be translated to a real-world case scenario, but it outperformed CM instruction in this study.

Carbon monoxide releasing molecule enhances coagulation and decreases fibrinolysis in canine plasma exposed to Crotalus viridis venom in vitro and in vivo.

Carbon monoxide releasing molecule-2 (CORM-2), an emerging therapeutic in human medicine, enhances plasmatic coagulation and attenuates fibrinolysis in vitro in human, rabbit and horse plasma and ameliorates hypocoagulation and hyperfibrinolysis secondary to venom exposure in human plasma in vitro. Fibrinogenases in rattlesnake venom cause decreased clot strength, and in the presence of tissue plasminogen activator (tPA) in vitro, a markedly increased rate of clot lysis. CO interacts with a haem group on fibrinogen, changing its configuration so that the fibrin clot is strengthened and more resistant to fibrinolysis. We hypothesized that CORM-2 enhances coagulation and attenuates fibrinolysis in canine plasma exposed to C viridis venom. We measured the effects of C viridis venom on clot strength, rates of coagulation and fibrinolysis in both pooled canine plasma and plasma from individual naturally envenomed dogs, with and without CORM-2, using thromboelastography (TEG). We tested venom effects on coagulation using tissue factor (TF) activated TEG and on both coagulation and fibrinolysis using TF-activated TEG with added tPA. We found that 17.9 µg/mL of venom causes a mean 26.4% decrease in clot strength, a 61.8% decrease in maximum rate of thrombus generation, 75% faster clot lysis, a 226% increase in maximum rate of lysis and a 92% decrease in total clot life span (CLS). CORM-2 ameliorated these effects, increasing CLS in the presence of venom by 603%. Additionally, we showed that CORM-2 has similar effects in vitro on plasma from naturally envenomed dogs, showing promise as an adjunct therapy for snake envenomation.

Effects of storage conditions on two platelet agonists for whole blood impedance platelet aggregometry in dogs.

BACKGROUND: Whole blood impedance platelet aggregometry (Multiplate-) can be performed with different agonists to evaluate platelet function. Although the manufacturer recommends disposal of stored reagents after 1 month at -20°C or 24 hours at 4°C, reagent integrity after reconstitution under different storage conditions is unknown. If reagent integrity is stable for longer periods, assay costs could decrease dramatically. OBJECTIVES: This study aimed to determine the stability of reconstituted arachidonic acid (AA) and adenosine diphosphate (ADP) platelet agonists stored at -20°C and -80°C for up to 6 months. METHODS: Aliquots of reconstituted AA and ADP were stored at -20°C and -80°C each month for a total of 6 months. Six healthy staff-owned dogs were enrolled in the study. A physical examination, CBC, diagnostic panel, urinalysis, and baseline platelet aggregometry assessment was performed on all of the dogs. Platelet aggregometry was performed using fresh and stored aliquots of AA and ADP reagents on the same day. The area under the curve (AUC) was recorded from each platelet aggregometry analysis. Repeated measures (RM) analysis (one-way ANOVA) was performed and subsequent time points (1, 2, 3, 4, 5, and 6 months) were compared with fresh AUC results. RESULTS: All dogs were clinically healthy, and all diagnostic tests were normal. There were no differences in AUC obtained from fresh samples at any time point or either temperature for AA or ADP. CONCLUSIONS: Whole blood impedance platelet aggregometry reagents, AA and ADP, were stable for up to 6 months when stored at -20°C or -80°C, obviating the need to discard viable reagents, and decreasing assay costs.

Reference intervals for coagulation variables in healthy adult domestic goats (Capra aegagrus hircus).

BACKGROUND: Coagulation has not been studied extensively in adult goats, and reference intervals (RIs) for coagulation variables have not yet been established and would be clinically useful. OBJECTIVES: The goal of this study was to establish coagulation variable RIs in adult goats for future coagulation interpretation. METHODS: Blood samples from 40 healthy adult goats were collected, and assays for PT, APTT, D-dimers, antithrombin III, and fibrinogen were performed. Coagulation variable RIs were established using the Reference Value Advisor v2.1. RESULTS: The RIs included: PT, 15.7-19.8 seconds; APTT, 16.2-24.3 seconds; D-dimer, 0-0.68 µg/mL; antithrombin III, 108.6%-156.5%; fibrinogen, 89.5-303.2 mg/dL. CONCLUSIONS: In this brief communication, we report the RIs for coagulation variables in healthy adult goats. Further research will be needed to identify coagulation changes that are associated with specific disease processes of goats.

Variability of tissue factor-activated thromboelastography and whole blood impedance platelet aggregometry in healthy dogs.

OBJECTIVE: To assess interindividual (CVG ) and intraindividual (CVI ) variability over time for results of thromboelastography (TEG) and whole-blood impedance platelet aggregometry in healthy dogs. ANIMALS: Six healthy Beagle dogs. MEASUREMENTS AND MAIN RESULTS: Tissue factor (TF)-activated TEG and adenosine diphosphate (ADP) and arachidonic acid (AA)-induced whole blood impedance platelet aggregometry were performed at 3 different time points (days 1, 4, and 6). In addition, platelet count, hematocrit, and plasma fibrinogen concentrations were recorded each study day. Activated partial thromboplastin time, one-stage prothrombin time, antithrombin activity, and D-dimer concentrations were measured on the first day of the study. For TEG, the variables reaction time (R), clotting time (K), rate of clot formation (α), and maximum amplitude (MA) were recorded. For platelet aggregometry, the areas under the curve for ADP (AUCADP )- and AA (AUCAA )-induced aggregation were measured. The CVI was lower than the CVG over time for MA, AUCADP , and AUCAA ; however, the CVI was higher than the CVG for the TEG variables R, K, and α. There were no statistical differences in the platelet count, hematocrit, and fibrinogen measurements over time. CONCLUSIONS: In healthy dogs, a subject-based reference interval for ADP- and AA-induced platelet aggregometry and the TEG variable MA provide a more sensitive method to detect changes. However, due to the high CVI , population-based reference intervals may be more appropriate for interpretation of the TEG variables R, K, and α.

Effects of Low-level Brodifacoum Exposure on the Feline Immune Response.

Anticoagulant rodenticides have been implicated as a potential inciting factor in the development of mange in wild felids, but a causative association between anticoagulant rodenticide exposure and immune suppression has not been established. Specific-pathogen-free domestic cats were exposed to brodifacoum over a 6-week period to determine whether chronic, low-level exposure altered the feline immune response. Cats were vaccinated with irrelevant antigens at different points during the course of the experiment to assess recall and direct immune responses. Measures of immune response included delayed-type hypersensitivity tests and cell proliferation assays. IgE and antigen-specific antibodies were quantified via ELISA assays, and cytokine induction following exposure to vaccine antigens was also analyzed. While cats had marked levels of brodifacoum present in blood during the study, no cats developed coagulopathies or hematologic abnormalities. Brodifacoum-exposed cats had transient, statistically significant decreases in the production of certain cytokines, but all other measures of immune function remained unaffected throughout the study period. This study indicates that cats may be more resistant to clinical effects of brodifacoum exposure than other species and suggests that the gross impacts of environmentally realistic brodifacoum exposure on humoral and cell-mediated immunity against foreign antigen exposures in domestic cats are minimal.

Iron protects porcine plasma coagulation kinetics from degradation by Crotalus atrox venom.

While the administration of antivenom to treat hemotoxic snake bite injury remains the gold standard of therapy, we have demonstrated that modifying human fibrinogen with iron and carbon monoxide renders it resistant to fibrinogenolytic snake venom enzymes. In order to translate these findings into a possible biometal-based therapy complementary to antivenom administration, a preclinical model that possesses fibrinogen that closely mimics the human molecule in response to iron and carbon monoxide needed to be identified. The goal of this investigation was to determine if a swine model could serve in this capacity by assessing the thrombelastographic response of porcine plasma to iron and carbon monoxide exposure, without or with further exposure to the fibrinogenolytic venom of the viper Crotalus atrox. Using plasma obtained from eight swine, it was determined that their plasma responded to iron and carbon monoxide in a manner similar to that of human plasma by displaying enhanced coagulation kinetics. However, in sharp contrast to the response seen with human plasma, only iron significantly protected porcine plasma coagulation kinetics from C. atrox venom degradation. Therefore the pig is an animal beyond humans that could derive benefit from the biometal-focused therapy of iron infusion to protect against venom mediated compromise of coagulation. Thus, future investigation to assess the effects of iron administration to attenuate the effects of fibrinogenolytic envenomation with a pig model is justified.

Clinically healthy overweight and obese dogs differ from lean controls in select CBC and serum biochemistry values.

BACKGROUND: Obesity is a global disease, affecting nearly half a billion people. Unfortunately, this trend is mirrored in our canine population. OBJECTIVES: As obesity is a complex inflammatory disease, there is a need to determine whether routine medical screening tests may indicate, or be influenced by, its presence. The objective of the current study was to determine if significant differences exist between CBC and biochemical profile values from control vs overweight/obese, client-owned dogs considered clinically healthy. METHODS: Dogs presented for routine health examinations, including minor dental or elective surgical procedures, were retrospectively identified from a hospital population. Animals were allocated to 2 categories based on body condition score (BCS), and data were analyzed by Mann-Whitney nonparametric analysis with statistical significance at a P ≤ .05. RESULTS: After exclusions, 116 dogs were assigned to the overweight/obese group (BCS ≥ 7) and 240 dogs to the control group (BCS = 4-6). Overweight/obese dogs had higher total leukocyte counts and higher plasma protein and globulin concentrations. Other differences were attributed to decreased serum water fraction (increased sodium, albumin, calcium, and anion gap) in the overweight/obese group. Interestingly, chloride concentration was decreased (in the face of increased sodium) in the obese group. CONCLUSIONS: There is CBC and biochemical evidence to support the concern that obesity influences laboratory values, even in dogs considered clinically healthy. Prospective studies aimed at characterizing these changes are needed to provide insight into the connection between obesity and its comorbidities.

Hematology and biochemistry of aging-evidence of "anemia of the elderly" in old dogs.

BACKGROUND: Effects of aging on hematologic and biochemical variables are well described in people. Anemia of the elderly is attributed to iron deficiency, anemia of chronic disease, chronic kidney disease, myelodysplasia, or idiopathic causes. Limited studies have examined these variables in aging dogs, but they have typically examined single breeds in research settings. OBJECTIVE: The objective of this study was to identify differences in CBC and biochemistry values between adult and aged dogs of many breeds. METHODS: Dogs presenting for wellness examinations and minor dental/elective surgeries that were otherwise clinically healthy were retrospectively identified. Dogs were categorized by age: adult (1-7.9 years), senior (8-11.9 years), and geriatric (12+ years). Standard CBC and biochemistry data were collated. Asian breeds, Greyhounds, and dogs with data indicating overt underlying disease were excluded. The Kruskal-Wallis test was used to compare groups with statistical significance set at P ≤ .05. RESULTS: Hematocrit, MCV, and serum iron decreased with age, indicating possible iron-restricted erythropoiesis (IRE), due to iron deficiency or low-grade chronic inflammation. Total proteins, globulins, and platelet counts increased with age while albumin decreased, suggesting low-grade inflammation. Urea was increased in older dogs without a concurrent increase in creatinine, which points toward gastrointestinal bleeding or dehydration. CONCLUSION: Clinically healthy, aging dogs have changes in laboratory variables that indicate altered physiologies compared to younger adult animals, including evidence of IRE, inflammation, and potential gastrointestinal bleeding, suggesting a similar trend to that of elderly human beings. Future studies will examine markers of iron metabolism and inflammation in aging dogs.

Pigments: Iron and Friends.

Iron, particularly hemosiderin, is a commonly observed pigment in cytology. Many pigments appear green to blue to black, making differentiation of pigment types difficult. While cytologic clues such as erythrophagia can help determine whether pigment is iron, Perl's Prussian Blue stain is used to highlight iron when these clues are not present. Other special stains can identify similar pigments such as copper. Identification of pigments is important as it directs cytologic interpretation, thus directly influencing patient diagnosis. This paper also presents basic iron metabolism, iron disorders in small animals, and laboratory assessment of iron disorders.

Modification of a commercial thromboelastography instrument to measure coagulation dynamics with three-dimensional biomaterials.

Three-dimensional synthetic constructs with complex geometries have immense potential for use in a multitude of blood-contacting applications. Understanding coagulation phenomena is arguably the most critical aspect for applications involving synthetic biomaterials; however, real-time evaluation of the clot formation while interfacing with these materials is difficult to achieve in a reproducible and robust manner. Here, work representing first steps toward addressing this deficit is presented, wherein modified consumables for a clinical instrument (a Thromboelastograph(®)) have been fabricated. Thromboelastography (TEG) measures viscoelastic properties throughout clot formation and therefore provides clinically relevant coagulation measurements in real time (i.e., kinetics and strength of clot formation). Through our modification, TEG consumables can readily accommodate three-dimensional materials (e.g., those for regenerative tissue applications). The authors performed proof-of-concept experiments using polymer scaffolds with a range of surface properties and demonstrated that variations in surface properties resulted in differences in blood plasma coagulation dynamics. For example, the maximum rate of thrombus generation ranged from 22.2 ± 2.2 (dyn/cm(2))/s for fluorocarbon coated scaffolds to 8.7 ± 1.0 (dyn/cm(2))/s for nitrogen-containing scaffolds. Through this work, the ability to make real-time coagulation activity measurements during constant coagulation factor interface with biomedically relevant materials is demonstrated.

Thromboelastographic evidence of inhibition of fibrinolysis after ε-aminocaproic acid administration in a dog with suspected acute traumatic coagulopathy.

OBJECTIVE: To describe the thromboelastographic changes in fibrinolysis with ε-aminocaproic acid treatment in a dog with suspected acute traumatic coagulopathy. CASE SUMMARY: A 9-year-old female spayed Airedale Terrier was presented with multiple injuries consistent with motor vehicle trauma. After surgical repair of a diaphragmatic hernia and minor laceration of the right cranial lung lobe, the dog continued to produce copious volumes of hemorrhagic fluid from the thoracic cavity despite multiple plasma transfusions, autotransfusions, and failure to locate a definitive source of bleeding during 2 separate surgeries. ε-Aminocaproic acid treatment was initiated and was associated with rapid clinical improvement and diminished fibrinolysis based on a modified plasma-based thromboelastogram. NEW OR UNIQUE INFORMATION PROVIDED: This report describes thromboelastographic evidence of inhibition of fibrinolysis after ε-aminocaproic acid administration in a dog with suspected acute traumatic coagulopathy. Thromboelastrography may be useful in monitoring therapy with antifibrinolytic drugs.

Reticulocyte hemoglobin content does not differentiate true from functional iron deficiency in dogs.

BACKGROUND: True and functional iron deficiency can result in anemia. Current tests to assess iron status often do not allow differentiation between these entities, which can affect optimal treatment. Previous work suggested low reticulocyte hemoglobin content (CHr) may be an early indicator of iron deficiency. OBJECTIVE: This study aimed to correlate several inflammation markers with CHr values in dogs. We hypothesize that dogs with low CHr values have hematologic and biochemical evidence of inflammation. METHODS: Animals with CHr values below the reference interval were included in the low CHr group, while dogs with normal or increased CHr were included in the control group. HCT, MCV, CHr, reticulocyte mean cell volume (MCVr), concentrations of serum iron, C-reactive protein (CRP), ferritin, and ceruloplasmin, and total iron-binding capacity (TIBC), percent transferrin saturation (% sat), and total WBC, neutrophil, and monocyte counts were determined. Nonparametric tests were performed; median values and percentage of abnormalities between each group were compared. RESULTS: Relative to control dogs, animals in the low CHr group had higher median values for CRP, ferritin, ceruloplasmin, and WBC concentration (P ≤ .05), and lower median values for HCT and MCV (P ≤ .0001). Higher frequencies of abnormalities for CRP, ferritin, WBC, neutrophil, and monocyte concentrations (P ≤ .02) were present in the low CHr group. CONCLUSIONS: Dogs with low CHr values often have evidence of inflammation, but low CHr did not reliably predict Fe deficiency. Additional diagnostic tests are needed to differentiate true and functional iron deficiency.

Pharmacokinetics and pharmacodynamics of the factor Xa inhibitor apixaban after oral and intravenous administration to cats.

OBJECTIVE: To determine pharmacokinetic and pharmacodynamic properties of the novel factor Xa inhibitor apixaban in clinically normal cats. ANIMALS: 5 purpose-bred domestic shorthair cats. PROCEDURES: A single dose of apixaban (0.2 mg/kg, PO) was administered to each cat (time 0), and blood samples were obtained at 0, 15, 30, 45, 60, 120, 240, 360, 480, and 1,440 minutes. After a 1-week washout period, another dose of apixaban (0.2 mg/kg, IV) was administered to each cat, and blood samples were obtained at 0, 5, 10, 15, 30, 45, 60, 120, 240, 360, 480, and 1,440 minutes. Apixaban concentrations in plasma were measured via liquid chromatography-tandem mass spectrometry. Pharmacodynamic effects of apixaban were determined with a commercial assay for factor × activity, which measures endogenous factor Xa activity chromogenically. RESULTS: Factor Xa was inhibited as a function of time after a single dose of apixaban administered orally or IV, and a direct inverse correlation with the plasma apixaban concentration was detected. Pharmacokinetic analysis revealed moderate clearance, short half-life, and high bioavailability for apixaban. A 2-compartment model was fit to the IV pharmacokinetic data; compartmental modeling could not be used to adequately describe the oral data because of substantial interindividual variability. CONCLUSIONS AND CLINICAL RELEVANCE: Results inticated that apixaban was an effective inhibitor of factor Xa in cats. Further studies will be needed to determine pharmacokinetics and pharmacodynamics after multidose administration, effects of cardiac disease on pharmacokinetics and pharmacodynamics, dosing recommendations, and efficacy of apixaban for use in the treatment and prevention of thromboembolic disease in cats.