Marie-Claude Blais

Clinical Leptospirosis in Three Cats (2001–2009)

Based on previous research, cats were thought to have been resistant to the development of clinical signs following infection with Leptospira spp. This case report presents three confirmed, naturally infected clinical cases of feline leptospirosis. The cases presented were all indoor/outdoor cats that were known to hunt. They were also all presented at different stages of renal insufficiency; however, they did not show any liver involvement. The authors suggest that there may be a longer incubation period in cats than dogs and recommend further research in the form of a large, clinical study.

Serologic and Urinary PCR Survey of Leptospirosis in Healthy Cats and in Cats with Kidney Disease

Background Although there is serologic evidence of exposure of cats to Leptospira spp., clinical disease is rarely reported in cats. Objective To compare the seropositivity and urinary polymerase chain reaction (PCR) status for Leptospira spp. between healthy (H) cats and cats with kidney disease (KD), to investigate the serovars potentially involved, and to evaluate potential risk factors. Animals Two hundred and forty client‐owned cats. Methods Cats were prospectively recruited and classified based on physical examination, complete blood count, serum biochemistry profile, and urinalysis (125 H and 115 KD cats). Leptospira spp. serology (titers ≥1 : 100 considered positive) and urinary PCR were performed in all cats. Data assessing risk factors, obtained from a questionnaire, were evaluated using logistic regression models. Results Seropositivity for Leptospira spp. was statistically different between groups: 7.2% (9/125) and 14.9% (17/114) in the H and KD, respectively (P = .05). The proportion of PCR‐positive cats was not. The most common serovars detected serologically were Pomona (n = 16) and Bratislava (n = 8). Risk factors for seropositivity included outdoor and hunting lifestyles (P = .03 and P < .001, respectively), the presence of another cat in the household (P < .01), and the sampling period, with the greatest number of cases identified between June and August (P =.02). Conclusions Seropositivity was significantly greater in KD cats, suggesting that the role of Leptospira spp. in KD in cats should be further investigated. The detection of urinary shedding of leptospires in several cats identifies a potential role in the transmission of the organism.

Lack of Evidence of Pregnancy‐Induced Alloantibodies in Dogs

BACKGROUND It is controversial whether or not pregnant bitches become sensitized to red blood cell (RBC) antigens. HYPOTHESIS Bitches do not develop alloantibodies to RBC antigens during gestation and can be used safely as blood donors. ANIMALS The study group included 35 healthy female dogs with a prior history of 1 (n = 12), 2 (n = 14), or >or= 3 (n = 9) pregnancies. The control group consisted of 15 healthy female dogs without any history of pregnancy. METHODS All dogs were blood typed for dog erythrocyte antigens (DEA) 1.1, 1.2, 3, 4, 5, and 7 using ethylenediaminetetraacetic acid blood samples and polyclonal antisera. Antibody screening was performed with serum and canine RBC panels of known blood type. An autocontrol and direct antiglobulin test were performed to rule out the presence of autoantibodies. RESULTS The only alloantibodies identified were those against DEA 7 and the prevalence of anti-DEA 7 alloantibodies was similar in dogs with known history of pregnancy (11.4%) and in the control group (13.3%). CONCLUSIONS AND CLINICAL IMPORTANCE These results confirm previous studies and clinical transfusion medicine experience. Naturally occurring anti-DEA 7 alloantibodies have been reported but their clinical relevance has not been shown. Pregnancy does not appear to sensitize dogs to RBC antigens. Consequently, dogs with prior history of pregnancy can be used safely as blood donors. Conversely, no additional pretransfusion compatibility studies would be required should these dogs themselves need to be transfused.

Update on Canine and Feline Blood Donor Screening for Blood-Borne Pathogens

An update on the 2005 American College of Veterinary Internal Medicine (ACVIM) Consensus Statement on blood donor infectious disease screening was presented at the 2015 ACVIM Forum in Indianapolis, Indiana, followed by panel and audience discussion. The updated consensus statement is presented below. The consensus statement aims to provide guidance on appropriate blood‐borne pathogen testing for canine and feline blood donors in North America.

Rivaroxaban demonstrates in vitro anticoagulant effects in canine plasma.

Rivaroxaban is an oral direct factor X inhibitor used in human thrombotic disorders and its oral administration makes it an attractive potential anticoagulant for dogs. The objective of this study was to evaluate the in vitro anticoagulant effect of rivaroxaban on canine pooled platelet-poor plasma (PPP). Pooled PPP was collected from 20 healthy adult Beagle dogs. Aliquots of pooled citrated PPP were treated in vitro with DMSO solutions of rivaroxaban (98% purity) to obtain 19 final concentrations ranging from 0 to 1000 mg/L of drug. Samples were immediately submitted for the following coagulation assays: prothrombin time (PT), activated partial thromboplastin time (aPTT), tissue factor-induced thrombin generation and anti-factor Xa activity. Concentration-effect data were analyzed with various nonlinear regression models for stimulatory or inhibitory effects. Rivaroxaban caused a concentration-dependent prolongation of all coagulation parameters. Rivaroxaban concentration for 50% baseline inhibition of the propagation phase of thrombin (rate index) was 0.024 mg/L, and for 50% baseline inhibition of the optical density in the anti-factor Xa activity assay was 0.053 mg/L. At these concentrations, PT and aPTT remained within the reference range. Two-fold prolongation from baseline of PT and aPTT was achieved with higher concentrations, i.e. 1.24 and 1.69 mg/L, respectively. Thrombin generation was completely suppressed by concentrations ≥0.8 mg/L. In conclusion, rivaroxaban showed an in vitro concentration-dependent anticoagulant effect on canine plasma. Thrombin generation and anti-factor Xa activity were more sensitive and accurate than PT and aPTT in detecting the anticoagulant effect of rivaroxaban.

Prevalence and Mode of Inheritance of the Dal Blood Group in Dogs in North America

Background The Dal blood group system was identified a decade ago by the accidental sensitization of a Dal− Dalmatian with a Dal+ blood transfusion. Similar Dal‐related blood incompatibilities have been suspected in other Dalmatians, Doberman Pinschers, and other breeds. Objectives To determine the prevalence and mode of inheritance of the Dal antigen expression in dogs. Animals A total of 1130 dogs including 128 Dalmatians, 432 Doberman Pinschers, 21 Shih Tzus, and 549 dogs of other breeds including 228 blood donors were recruited from North America between 2008 and 2015. Methods Prospectively, dogs were blood typed for Dal applying a gel column technique using polyclonal canine anti‐Dal sera. Pedigrees from 8 typed families were analyzed. Results The prevalence of the Dal+ blood type varied between 85.6 and 100% in Dalmatians and 43.3–78.6% in Doberman Pinschers depending on geographical area. Dal− dogs were identified mostly in Dalmatians (15/128; 11.7%), Doberman Pinschers (183/432; 42.4%), and Shih Tzus (12/21; 57.1%), and sporadically in mixed‐breed dogs (3/122; 2.5%), Lhasa Apsos (1/6) and Bichon Frises (1/3). Only 6/245 (2.4%) blood donors were found to be Dal−, including 5 Doberman Pinschers. The mode of inheritance of the Dal+ phenotype was determined to be autosomal dominant. Conclusions and Clinical Importance The high percentage of Dal− Doberman Pinchers, Dalmatians and Shih Tzus increases their risk of being sensitized by a blood transfusion from the common Dal+ donor. Extended Dal typing is recommended in those breeds and in dogs when blood incompatibility problems arise after initial transfusions.

Comparison of gravity collection versus suction collection for transfusion purposes in dogs.

Blood donation is an essential step in transfusion medicine that must take into account the donors welfare, collection effectiveness, and blood product quality. This prospective study enrolled 13 canine blood donors, each subjected to both gravity and suction collection methods, in a randomized order. Clinical parameters, including heart rate (HR), respiratory rate (RR), systolic blood pressure (SBP), and rectal temperature (RT), were evaluated at four time points, including when the donor was on the floor and on the collection table, and before and after blood donation. The number of times the donor and needle required repositioning, the duration of the donation, the noise created by the apparatus, and the presence of a hematoma were evaluated. The weight, index of hemolysis, and hematocrit of each unit of blood were recorded. There was no significant difference between collection methods for either the clinical parameters at each time point or the prevalence of hematoma formation, the frequency of needle repositioning, the hemolysis index, or hematocrit. Collection by suction was noisier (P < 0.0001), faster (P = 0.004), and associated with significantly less donor repositioning (P = 0.007). Suction appears to be a safe and cost-effective method that should be considered to optimize blood donation.

Anticoagulant activity of oral rivaroxaban in healthy dogs

Rivaroxaban is an oral, direct factor Xa inhibitor used in human thrombotic disorders. In view of the in vitro concentration dependent anticoagulant effects of rivaroxaban in dogs, the time course of its anticoagulant effects was characterized in healthy dogs. Twenty-four healthy Beagles were randomized into three groups (n = 8 per group) and received orally either a placebo or 20 mg rivaroxaban once or twice at an 8 h interval. Fifteen blood samples were collected over a 30 h period, and blindly assayed for prothrombin time (PT), activated partial thromboplastin time (aPTT), tissue factor induced thrombin generation (TG) and anti-factor Xa activity. Thromboelastography (TEG) was evaluated at 0, 1, 4, 8 and 24 h. Peak/baseline anticoagulant effect ratios were analyzed with generalized linear models using β distributions and times to return to baseline with survival analyses (α = 0.05). Peak/baseline anticoagulant effect ratios of PT, aPTT, anti-factor Xa activity, TG and R (TEG) differed significantly between placebo and both rivaroxaban groups (P <0.0001). The peak anticoagulant effect of rivaroxaban occurred 1.5 to 2 h after dosing. The median return to baseline occurred significantly sooner (P <0.01) with 20 mg rivaroxaban administered once (7.9-18.7 h) versus twice (17.5-26.8 h). The inter-individual variability differed amongst assays, but overall was moderate to large. No adverse effects were recorded. Twice oral administration of 2 mg/kg rivaroxaban at an 8 h interval maintained 24 h anticoagulant activity, but larger studies are needed to establish guidelines for the use of rivaroxaban in dogs.