Kliniske og klinisk-patologiske aspekter ved hoggormbitt hos hund

Envenomation of dogs by the European adder (Vipera berus (V. berus)) is a common emergency in veterinary practice in Europe. Despite its common nature, little research exists regarding the clinical effects of this type of snakebite in dogs. In this thesis, clinical and clinicopathological effects were prospectively and longitudinally assessed in dogs envenomated by V. berus with an emphasis on cardiac, renal and haemostatic systems. Whether severity of initial clinical signs might give an indication as to the subsequent development of effects on these body systems, was also of interest. Dogs naturally envenomated by V. berus and presenting to the small animal clinics at NMBU Oslo, Evidensia Oslo Dyresykehus, Anicura Dyresykehus Oslo and Anicura Jeløy Dyresykehus, during 2017 and 2018, were recruited to the studies. A total of 60 envenomated dogs were included in different parts of the project and were assessed at five timepoints after bite, from presentation to the clinic to two weeks after bite. Data collection involved severity scoring of clinical signs, continuous 48- hour ambulatory electrocardiography (ECG), serum cardiac troponin I (cTnI, a cardiac injury biomarker) measurement, serum and urine biomarkers for kidney function and injury, and plasma coagulation parameters. The main findings were: - During the first 48 hours after envenomation, a large proportion of dogs developed myocardial injury, detected as a ventricular arrhythmia (12/21, 56%) or increased cTnI concentrations ( 17/21, 81%). Severe arrhythmias were detected in 6 of 21 (29%) dogs. Myocardial injury appeared to have resolved 14 days after bite (Paper I). - There was evidence of mild, transient, non-azotaemic acute kidney injury (AKI) in dogs after V. berus envenomation, as measured by novel urinary AKI biomarkers and compared to a group of healthy control dogs. However, further assessment of many of the urinary biomarkers used in these studies is needed to elucidate their specificity for AKI , especially in the face of concurrent systemic inflammation (Papers II and III). - Envenomated dogs in this cohort were hypercoagulable already at presentation and still at 15 days after V. berus envenomation, as measured using a thrombin generation assay, thrombin-antithrombin complexes and phosphatidylserine equivalents, and compared to a group of healthy controls. Dogs that that receive antivenom treatment might be less hypercoagulable than their non-antivenom treated counterparts (Paper IV). - The severity of clinical signs at presentation was not generally a useful indicator for the subsequent development of clinical or clinicopathological effects in this cohort of envenomated dogs (Papers I-III). This thesis provides new insights into the effects of V. berus envenomation in dogs and contributes to the generally sparse evidence base upon which treatment and monitoring decisions of these patients can be made. Based on the cardiac and renal effects observed in this cohort of envenomated dogs, prolonged ECG monitoring for ventricular tachycardia and hospitalisation with supportive intravenous fluid therapy, appear to be sensible recommendations after V. berus bites in dogs. The clinical significance of the hypercoagulable state detected is unclear, but coagulation parameters measured in paper IV may serve as laboratory endpoints in future randomised controlled trials of antivenom efficacy.Sykdom forårsaket av bitt av hoggorm (Vipera berus) er vanlig blant hunder i store deler av Europa. På tross hyppig forekomst er de kliniske effektene av hoggormbitt hos denne arten mangelfullt beskrevet. I dette doktorgradsprosjektet ble kliniske og klinisk-patologiske effekter av hoggormbitt hos hund studert prospektivt, med hovedvekt på bittets effekter på hjerte, nyrer og koagulasjon. I tillegg ble det undersøkt om alvorlighetsgraden av kliniske sykdomstegn ved ankomst til dyreklinikk kunne forutsi i hvilken grad de studerte organsystemene ville rammes. Hunder med hoggormbitt som ble behandlet ved smådyrklinikken ved Norges miljø og biovitenskapelige universitet (NMBU), Evidensia Oslo Dyresykehus, Anicura Dyresykehus Oslo og Anicura Jeløy Dyresykehus i løpet av 2017 og 2018 ble inkludert i studien, og totalt deltok 60 hunder i de ulike delene av prosjektet. Data ble samlet ved fem ulike tidspunkter, fra presentasjon på klinikk og frem til to uker etter bitt, og inkluderte en klinisk vurdering ved hjelp av et scoringssystem, kontinuerlig 48-timers ambulatorisk elektrokardiografi (EKG), serumnivåer av troponin I (cTnI, markør for hjerteskade), biomarkører for nyrefunksjon og akutt nyreskade (AKI) i serum og urin, samt koagulasjonsparametere i plasma. Hovedfunnene i forskningsprosjektet kan oppsummeres i de følgende punktene: - En betydelig andel av hundene utviklet myokardskade i løpet av de første 48 timene etter hoggormbittet, definert som ventrikulære arytmier (12/21, 56%) eller forøkede cTnI konsentrasjoner (17/21, 81%). Alvorlige arytmier ble oppdaget hos 6 av 21 (29%) av hundene. Etter 14 dager var avvikene normaliserte (Artikkel I). - Ved hjelp av nyere biomarkører i urin for AKI, ble en mild, kortvarig, ikkeazotemisk AKI identifisert blant hundene som var bitt av hoggorm, ved sammenligning mot data fra en gruppe friske kontrollhunder. Videre studier er nødvendig for å klargjøre spesifisiteten til flere av disse urinmarkørene, særlig i pasienter med systemisk inflammasjon (Artikkel II og III). - Ved målinger av trombingenerering, trombin-antitrombinkomplekser og fosfatidylserin ekvivalenter, ble det funnet at hunder med hoggormbitt var hyperkoagulable allerede ved ankomst til klinikk, og fremdeles etter 15 dager, sammenlignet med en gruppe friske kontrollhunder. Hunder som ble behandlet med antivenin var mindre hyperkoagulable sammenlignet med hunder som ikke mottok denne behandlingen (Artikkel IV). - Alvorlighetsgrad av kliniske sykdomstegn ved ankomst til klinikk samsvarte ikke med grad av myokard- eller nyreskade i denne kohorten med hunder bitt av huggorm (Artikler I-III). Denne avhandlingen gir ny innsikt i effektene av huggormbitt hos hund, og bidrar til økt kunnskap som behandling og overvåkning av disse pasientene kan baseres på. Ut ifra effektene på hjerte og nyrer observert i denne studien, vil innleggelse og observasjon, inkludert EKG-overvåkning, samt intravenøs væskebehandling være et hensiktsmessig behandlingsregime ved denne tilstanden. Den kliniske betydningen av den hyperkoagulable tilstanden til hunder bitt av hoggorm er foreløpig usikker, men koagulasjonsparametere brukt i artikkel IV kan være til nytte i randomiserte kontrollerte kliniske studier med hensikt å vurdere klinisk effekt av antiveninbehandling ved huggormbitt hos hund.The Raagholt Research Foundation ; Arkitekt Finn Rahn's Fund ; Dyrlege Smiths Fund ; The Agria and SKK Research Fund for Pet

Persistent hypercoagulability in dogs envenomated by the European adder (Vipera berus berus)

Background Envenomation by the European adder, Vipera berus berus (Vbb), is a medical emergency. The overall in vivo haemostatic effects of pro- and anticoagulant components in Vbb venom, and the downstream effects of cellular injury and systemic inflammation, are unclear. Objectives To longitudinally describe the global coagulation status of dogs after Vbb envenomation and compare to healthy controls. A secondary aim was to investigate differences between dogs treated with and without antivenom. Methods Citrated plasma was collected at presentation, 12 hours (h), 24 h, 36 h and 15 days after bite from 28 dogs envenomated by Vbb, and from 28 healthy controls at a single timepoint. Thrombin generation (initiated with and without exogenous phospholipids and tissue factor), thrombin-antithrombin (TAT)-complexes and the procoagulant activity of phosphatidylserine (PS)-expressing extracellular vesicles (EVs), expressed as PS-equivalents, were measured. Results At presentation the envenomated dogs were hypercoagulable compared to controls, measured as increased thrombin generation, TAT-complexes and PS-equivalents. The hypercoagulability decreased gradually but compared to controls thrombin generation and PS-equivalents were still increased at day 15. The discrepancy in peak thrombin between envenomated dogs and controls was greater when the measurement was phospholipid-dependent, indicating that PS-positive EVs contribute to hypercoagulability. Lag time was shorter in non-antivenom treated dogs, compared to antivenom treated dogs <24 h after envenomation. Conclusions Hypercoagulability was measured in dogs up to 15 days after Vbb envenomation. Dogs treated with antivenom may be less hypercoagulable than their non-antivenom treated counterparts. Thrombin generation is a promising diagnostic and monitoring tool for Vbb envenomation.publishedVersio

Venom-Induced Blood Disturbances by Palearctic Viperid Snakes, and Their Relative Neutralization by Antivenoms and Enzyme-Inhibitors

Palearctic vipers are medically significant snakes in the genera Daboia, Macrovipera, Montivipera, and Vipera which occur throughout Europe, Central Asia, Near and Middle East. While the ancestral condition is that of a small-bodied, lowland species, extensive diversification has occurred in body size, and niche specialization. Using 27 venom samples and a panel of in vitro coagulation assays, we evaluated the relative coagulotoxic potency of Palearctic viper venoms and compared their neutralization by three antivenoms (Insoserp Europe, VIPERFAV and ViperaTAb) and two metalloprotease inhibitors (prinomastat and DMPS). We show that variation in morphology parallels variation in the Factor X activating procoagulant toxicity, with the three convergent evolutions of larger body sizes (Daboia genus, Macrovipera genus, and Vipera ammodytes uniquely within the Vipera genus) were each accompanied by a significant increase in procoagulant potency. In contrast, the two convergent evolutions of high altitude specialization (the Montivipera genus and Vipera latastei uniquely within the Vipera genus) were each accompanied by a shift away from procoagulant action, with the Montivipera species being particularly potently anticoagulant. Inoserp Europe and VIPERFAV antivenoms were both effective against a broad range of Vipera species, with Inoserp able to neutralize additional species relative to VIPERFAV, reflective of its more complex antivenom immunization mixture. In contrast, ViperaTAb was extremely potent in neutralizing V. berus but, reflective of this being a monovalent antivenom, it was not effective against other Vipera species. The enzyme inhibitor prinomastat efficiently neutralized the metalloprotease-driven Factor X activation of the procoagulant venoms. In contrast, DMPS (2,3-dimercapto-1-propanesulfonic acid), which as been suggested as another potential treatment option in the absence of antivenom, DMPS failed against all venoms tested. Overall, our results highlight the evolutionary variations within Palearctic vipers and help to inform clinical management of viper envenomation

Clinical and clinicopathological characteristics in canine Vipera berus envenomation

Envenomation of dogs by the European adder (Vipera berus (V. berus)) is a common emergency in veterinary practice in Europe. Despite its common nature, little research exists regarding the clinical effects of this type of snakebite in dogs. In this thesis, clinical and clinicopathological effects were prospectively and longitudinally assessed in dogs envenomated by V. berus with an emphasis on cardiac, renal and haemostatic systems. Whether severity of initial clinical signs might give an indication as to the subsequent development of effects on these body systems, was also of interest. Dogs naturally envenomated by V. berus and presenting to the small animal clinics at NMBU Oslo, Evidensia Oslo Dyresykehus, Anicura Dyresykehus Oslo and Anicura Jeløy Dyresykehus, during 2017 and 2018, were recruited to the studies. A total of 60 envenomated dogs were included in different parts of the project and were assessed at five timepoints after bite, from presentation to the clinic to two weeks after bite. Data collection involved severity scoring of clinical signs, continuous 48- hour ambulatory electrocardiography (ECG), serum cardiac troponin I (cTnI, a cardiac injury biomarker) measurement, serum and urine biomarkers for kidney function and injury, and plasma coagulation parameters. The main findings were: - During the first 48 hours after envenomation, a large proportion of dogs developed myocardial injury, detected as a ventricular arrhythmia (12/21, 56%) or increased cTnI concentrations ( 17/21, 81%). Severe arrhythmias were detected in 6 of 21 (29%) dogs. Myocardial injury appeared to have resolved 14 days after bite (Paper I). - There was evidence of mild, transient, non-azotaemic acute kidney injury (AKI) in dogs after V. berus envenomation, as measured by novel urinary AKI biomarkers and compared to a group of healthy control dogs. However, further assessment of many of the urinary biomarkers used in these studies is needed to elucidate their specificity for AKI , especially in the face of concurrent systemic inflammation (Papers II and III). - Envenomated dogs in this cohort were hypercoagulable already at presentation and still at 15 days after V. berus envenomation, as measured using a thrombin generation assay, thrombin-antithrombin complexes and phosphatidylserine equivalents, and compared to a group of healthy controls. Dogs that that receive antivenom treatment might be less hypercoagulable than their non-antivenom treated counterparts (Paper IV). - The severity of clinical signs at presentation was not generally a useful indicator for the subsequent development of clinical or clinicopathological effects in this cohort of envenomated dogs (Papers I-III). This thesis provides new insights into the effects of V. berus envenomation in dogs and contributes to the generally sparse evidence base upon which treatment and monitoring decisions of these patients can be made. Based on the cardiac and renal effects observed in this cohort of envenomated dogs, prolonged ECG monitoring for ventricular tachycardia and hospitalisation with supportive intravenous fluid therapy, appear to be sensible recommendations after V. berus bites in dogs. The clinical significance of the hypercoagulable state detected is unclear, but coagulation parameters measured in paper IV may serve as laboratory endpoints in future randomised controlled trials of antivenom efficacy

Ambulatory Electrocardiography and Serum Cardiac Troponin I Measurement in 21 Dogs Envenomated by the European Adder (Vipera Berus)

Background: Envenomation by the European adder (Vipera berus) is common in dogs in Europe. Cardiac arrhythmias occur but clinical studies of envenomated dogs are limited. Objectives: To describe arrhythmias in dogs within 48 hours of envenomation, and investigate associations between arrhythmia grade, serum troponin I (cTnI), and snakebite severity score (SS score). Animals: Twenty-one client-owned dogs bitten by V berus. Methods: Prospective cohort study of envenomated dogs. Ambulatory electrocardiograms were recorded from presentation to 48 hours after snakebite, and arrhythmias graded 0 to 3 based on frequency and severity. Serum cTnI was measured at presentation, 12 hours, 24 hours, 36 hours, and 14 days after bite. An SS score of 1 to 3 was recorded at admission and based on clinical examination. Results: All dogs survived. Twelve dogs (57%) developed arrhythmias, all of which were ventricular in origin. Severe complex ventricular arrhythmias (VAs) were observed in 6 dogs (29%). Eighty-one percent of dogs (n = 17) had increased cTnI concentrations at 1 or more time points. Dogs that developed arrhythmias had significantly higher concentrations of cTnI at 12 hours (1.67 [0.04-32.68] versus 0.03 [0.01-0.052]; P = .002), 24 hours (1.88 [0.2-14.23] versus 0.06 [0.01-2.06]; P = .009), and 36 hours (3.7 [0.02-16.62] versus 0.06 [0.01-1.33]; P = .006) after bite compared to those that did not. Contingency table analysis showed that SS score was not significantly associated with arrhythmia grade (P = .9).publishedVersio

Ambulatory Electrocardiography and Serum Cardiac Troponin I Measurement in 21 Dogs Envenomated by the European Adder (Vipera Berus)

Background: Envenomation by the European adder (Vipera berus) is common in dogs in Europe. Cardiac arrhythmias occur but clinical studies of envenomated dogs are limited. Objectives: To describe arrhythmias in dogs within 48 hours of envenomation, and investigate associations between arrhythmia grade, serum troponin I (cTnI), and snakebite severity score (SS score). Animals: Twenty-one client-owned dogs bitten by V berus. Methods: Prospective cohort study of envenomated dogs. Ambulatory electrocardiograms were recorded from presentation to 48 hours after snakebite, and arrhythmias graded 0 to 3 based on frequency and severity. Serum cTnI was measured at presentation, 12 hours, 24 hours, 36 hours, and 14 days after bite. An SS score of 1 to 3 was recorded at admission and based on clinical examination. Results: All dogs survived. Twelve dogs (57%) developed arrhythmias, all of which were ventricular in origin. Severe complex ventricular arrhythmias (VAs) were observed in 6 dogs (29%). Eighty-one percent of dogs (n = 17) had increased cTnI concentrations at 1 or more time points. Dogs that developed arrhythmias had significantly higher concentrations of cTnI at 12 hours (1.67 [0.04-32.68] versus 0.03 [0.01-0.052]; P = .002), 24 hours (1.88 [0.2-14.23] versus 0.06 [0.01-2.06]; P = .009), and 36 hours (3.7 [0.02-16.62] versus 0.06 [0.01-1.33]; P = .006) after bite compared to those that did not. Contingency table analysis showed that SS score was not significantly associated with arrhythmia grade (P = .9)

Serial serum creatinine, SDMA and urinary acute kidney injury biomarker measurements in dogs envenomated by the European adder (Vipera berus)

publishedVersio