| Summary: | 博士 === 國立臺灣大學 === 獸醫學研究所 === 105 === Anemia is a common hematologic abnormality in dogs, however, few data are available regarding epidemiology and causes in Taiwan. To investigate the causes of anemia [hematocrit (Hct) < 37%] in dogs, 3208 anemic cases collected between January 2008 and December 2012 at National Taiwan University Veterinary Hospital (NTUVH) were analyzed. Dogs under the age of six months were further collected as puppy group (Hct <22%). In dogs over the age of six months group, among the 2037 dogs with identifiable causes, 70.4% (1435 dogs) were induced by single cause, whereas 29.6% (602 dogs) by multiple causes. Cancer-related anemia (CRA, 460/1435, 32.1%), infectious pathogen-related anemia (IPRA, 287/1435, 20.0%) and renal disease-related anemia (251/1435, 17.6%) are the frequent causes anemia in dogs. Furthermore, IPRA (59.7%) is the primarily result the very severe anemia. Of the 43 infectious disease-related very severe anemic dogs, the most commonly diagnosed pathogen was Babesia gibsoni (B. gibsoni; 83.7%, n = 36). In puppy group, among the 34 dogs examined, the causes of anemia could not be identified in 21 (61.7%) animals. For the remaining dogs, 13 dogs were classified as anemic with a single cause. Canine distemper virus is the most important pathogen causing anemia in puppies and the mortality rate was 100% in this study. Taken together, infectious disease is one of the frequent causes of canine anemia in Taiwan. B. gibsoni and canine distemper appeared to be the most important infectious pathogen causing anemia in dogs over 6 months and puppies, respectively.
B. gibsoni is increasingly recognizes as a cause of canine tick-borne disease in worldwide. However, only a few clinical characteristics and laboratory findings regarding naturally infected B. gibsoni were available. Most of the published reports were mixed with a distinct species, i.e. B. conradae. 62 dogs, with full medical records and positive B. gibsoni PCR results, from January 2014 to December 2015 presented at National Taiwan University Veterinary Hospital (NTUVH), were enrolled in this study. Of 62 dogs recruited, 24 (38.7%) had concurrent disease, 38 (61.3%) had B. gibsoni infection alone. Two dogs were excluded because of concurrent with immune mediated hemolytic anemia, which may dramatically impact the anemic severity. The severity of anemia between B. gibsoni infected and concurrent disease groups showed no significant different (P > 0.05). The common observed hematological abnormality were anemia (49/60, 81.7%) and thrombocytopenia (39/60, 65%). 42 of 35 dogs (70.0%) had moderate to very severe anemia. The main biochemical abnormalities were included hyperglobulinemia (28/53, 52.8%), hyperbilirubinemia (10/28, 35.7%), and elevated hepatic enzyme activities (7/48, 14.6%). Dogs that didn’t regularly received ectoparasidal agents had higher infection rate of B. gibsoni infection.
Several drug combinations have been used to treat B. gibsoni infection. A combination of atovaquone and azithromycin has been widely used throughout the world, particularly in areas with epidemics. However, the drug-resistant atovaquone strain is known to be influenced by various mutations, particularly the substitution of methionine with isoleucine (M121I) in the B. gibsoni cytochrome b (CYTb) gene. Rapid identification of the drug-resistant strain is required to select a more effective combination of drugs. A SimpleProbe® real-time PCR assay was designed to detect the single nucleotide polymorphism at nucleotide 363 in CYTb gene of B. gibsoni and the sensitivity and specificity were evaluated by comparing the results from the conventional DNA sequencing method. When detecting the M121I mutation, 42 of 42 mutant samples were identified, with a sensitivity of 100%, and 45 of 47 wild type samples were identified, with a specificity of 95.7%. Furthermore, we use the SimpleProbe® assay to investigate the naturally ATV-resistant strain of B. gibsoni in Taiwan. 95 dog blood samples confirmed with B. gibsoni infection by PCR method from January 2014 to December 2015. Of all 95 samples, 52 samples were collected from the client-owned dogs in NTUVH and 33 samples were collected from the free-roaming dogs. 3 of client-owned dogs (3/52, 5.8%) and 5 of free roaming dogs (5/33, 15.2%) were detected the M121I mutation. Only one of them had ever been treated with AA combinations. This is the first report that naturally atovaquone-resistant B. gbisoni strain existed in Taiwan.
Canine distemper (CD), caused by a morbillivirus of the family Paramyxoviridae, occurs worldwide and is one of the most contagious and lethal diseases especially in juvenile dogs. The clinical feasibility of passive immunotherapy has not been demonstrated in dogs naturally infected with canine distemper. In this study, porcine anti-canine distemper virus IgG and F(ab’ )2 antibody fragments were used to treat infected puppies. A total of 41 naturally infected puppies (age < six months) exhibiting severe respiratory signs, but lacking neurological signs, were enrolled in the study. Twenty-five puppies were treated with a combination of IgG or F(ab’ )2 antibody fragments (Group 1) and supportive therapy and 16 puppies received routine supportive care only (Group 2). The survival rate of dogs in Group 1 (19/25; 76%) was significantly higher than that in Group 2 (5/16; 31·3%) (P < 0.05). During the therapy, 8 of the 25 dogs (32%) in Group 1 developed neurological signs versus 12 of the 16 dogs (75%) in Group 2 (P < 0.05). Adverse reactions were limited to elevated body temperature in dogs that received IgG antibodies. Porcine anti-canine distemper virus antibodies improved survival in puppies affected with canine distemper with minimal adverse effects. Therefore, this therapy could be considered for treatment of endangered animal species infected with canine distemper virus.
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