Use of low-molecular-weight heparin to decrease mortality in mice after intracardiac injection of tumor cells

Intracardiac injection of human tumor cells into anesthetized nude mice is an established model of bone metastasis. However, intracardiac injection of some human tumor cell lines cause acute neurologic signs and high mortality, making some potentially relevant tumor cell lines unusable for investigation. We showed that intracardiac injection of tumor cells can induce a hypercoagulable state leading to platelet consumption and thromboemboli formation and that pretreatment with intravenous injection of low-molecular-weight heparin (LMWH; enoxaparin) blocks this state. In addition, intravenous injection of enoxaparin before intracardiac injection with 2 different small-cell lung carcinoma lines, H1975 and H2126, dramatically decreased mouse mortality while still generating bone metastases. Therefore, reduction of mortality by pretreatment with LMWH increases the types of cells that can be studied in this metastasis model and decreases the number of animals used.

Efficacy and safety of five injectable anesthetic regimens for chronic blood collection from the anterior vena cava of Guinea pigs

Despite several published methods of inducing surgical anesthesia in guinea pigs, viable methods of anesthesia for blood collection from the vena cava are inadequate. We compared 5 anesthesia regimens and their efficacy in inducing anesthesia for blood sampling in guinea pigs: ketamine-xylazine (30 and 2.5 mg/kg) administered subcutaneously, intramuscularly, or intraperitoneally; pentobarbital (37 mg/kg) administered intraperitoneally; and medetomidine (0.5 mg/kg) administered intramuscularly. Parameters measured included time to onset of anesthesia, time to recovery from anesthesia, and complete blood count (CBC) and serum chemistry values. CBC values did not differ among the 5 regimens, but serum glucose, BUN, phosphorous, and creatine phosphokinase levels varied among groups. Based on our data, intraperitoneal ketamine-xylazine appears to emerge as a preferable injectable anesthetic regimen in guinea pigs for blood collection from the anterior vena cava.

Retrospective clinical and molecular analysis of conditioned laboratory dogs (Canis familiaris) with serologic reactions to Ehrlichia canis, Borrelia burgdorferi, and Rickettsia rickettsii

Dogs are susceptible to different tickborne infections, including members of the Anaplasmataceae (Ehrlichia canis, E. ewingii, E. chaffeensis, Anaplasma phagocytophilum, A. platys), Borrelia burgdorferi, and Rickettsia rickettsii. These diseases can manifest with clinical signs including fever, anorexia, malaise, lameness, rash, and bleeding episodes; however, these signs are nonpathognomonic, and infections can occur in the absence of clinical signs. Hematologic abnormalities can include leukopenia, thrombocytopenia, hyperproteinemia and hypergammaglobulinemia. In biomedical research, diseases such as canine monocytic ehrlichiosis, Lyme disease, and Rocky Mountain spotted fever may cause morbidity among exposed dogs and confound research results. Random-source dogs are susceptible to these diseases because of their increased risk of arthropod exposure. Nonpurpose bred, randomly selected conditioned dogs (n = 21) were examined; blood samples were taken for hematology, biochemistry analysis, tickborne pathogen serology, and PCR. Of these, 2 dogs (10% of the population) presented with illness characterized by fever, malaise, lameness, or hemostatic abnormalities, and 15 (71%) had antibodies to one or more tickborne pathogens. No specific hematologic or biochemical differences were apparent between seronegative dogs and seropositive dogs reactive to all 3 pathogens. E. canis and B. burgdorferi PCR of tissues and blood were negative for all dogs. PCR amplification of several Ehrlichia and Anaplasma genes yielded no positive samples. From this cohort of dogs, serologic and molecular results indicate prior exposure without active infection or clinical disease. Exposure to and potential for infection with these bacteria and other pathogens may contribute to blood and tissue alterations that could confound experiments and lead to misinterpretation of data in canine models.