犬猫用药误区

1犬猫有别,用药各异犬、猫吸收和排泄药物的途径基本相同,但犬猫对不同药物的吸收和排泄有所差异。即使同为犬或猫,也会由于品种、体型、年龄及体况的差异而出现用同一药物后治疗结果有所差异。如有机磷药物、阿斯匹林等,由于猫肝脏中缺乏葡萄糖醛酸基转移酶而对类药排泄较慢,而这类药犬可正常使用。又如大多数犬使用常量伊维菌素不会引起异常,但柯利犬使用伊维菌素后则易引起中毒。2不切实际,滥用药物主要表现在不能对症下药,不能根据病情、药物特性正确给药或随意增减给药剂量、时间、次数;不注意动物种类、性别、年龄及个体间的差异;不合…     

柯利犬通灭中毒的临床症状和治疗

在犬的皮肤病中,由疥螨或蠕形螨引起的病例占相当大的比重。首选治疗药物是伊维菌素,但一般禁用于柯利犬,而新一代灭螨药物通灭可以用于柯利犬的皮肤治疗。然而,在应用的过程中,却发现偶有柯利犬中毒的现象发生,对柯利犬通灭中毒的临床症状和治疗方法进行了介绍供参考。     

犬伊维菌素中毒的救治

1 发病情况 2000年至2005年，在门诊就诊犬中，出现十几例伊维菌素和阿维菌素中毒人，多为北京犬、吉娃娃、小鹿犬等小体型品种犬和柯利牧羊犬。多为剂量过大，注射或口服间隔过短，注射剂量超过每天0．5mg／kg体重或口服超过2．0mg／kg体重。间隔时间低于7天，或肌肉注射，均易引起中毒。柯利牧羊犬对伊维菌素特别敏感，即使50μg／kg体重伊维菌素，也可引起严重中毒反应。发病较急，往往于注射或口服12～24h后发病，如不及时救治，死亡率可达100％。     

动物伊维菌素中毒治疗

正1病因1.1动物伊维菌素用量过大或用药间隔时间过短可引起中毒。1.2伊维菌素注射液供皮下注射,若采用肌肉、静脉注射则易引起中毒。1.3伊维菌素中毒与动物品种和年龄有关,有的品种的犬对其异常敏感,药物小剂量使用即可引起中毒,甚至死亡。伊维菌素对虾、鱼等水生生物为剧毒药物。2中毒症状2.1犬、猫中毒犬、猫表现出神经症状,轻者中枢神经受抑制,重者中枢神经兴奋,因中毒程度不同,犬、猫可出现运动麻痹和共济失调。急性病     

动物伊维菌素中毒的诊治

伊维菌素是由阿维链菌产生的半合成大环内酯类多组分抗生素,对动物的体内外寄生虫,特别是线虫和节肢动物有良好的驱杀作用,是治疗小动物疾病的临床常用药,也用于猪和家禽体外寄生虫的防治。1 病因与症状伊维菌素对犬的体内外寄生虫,如线虫、跳蚤、虱、蜱、螨虫及心丝虫微丝蚴虫等感染有很好的驱杀作用。使用剂量过大或使用的时间间隔太短可引起中毒,柯利犬对伊维菌素尤为敏感。     

伊维菌素中毒致犬猫视觉障碍的诊治

<正>伊维菌素是一种大环内酯类抗寄生虫药,能驱除犬的钩虫、蛔虫、心丝虫及其蚴,对螨、蜱、虱、蝇等也有较强的驱杀作用。因其具有广谱、高效、用量小、副反应轻等优点广泛应用于兽医临床。在宠物临床中,它常常被作为首选药物来驱杀体内线虫和体外寄生虫。在正常情况下,按照推荐剂量使用伊维菌素不易致使犬猫发生中毒反应(柯利犬除外),但是,如果用药量过大、短时间重复用药或因犬猫个体差异,也会发生中毒。伊维菌素致犬中毒病例     

浅析犬伊维菌素中毒机理及解救措施

伊维菌素是一类半合成大环内酯类多组分广谱抗寄生虫药,对动物体内线虫及疥螨、蜱、血虱等体外寄生虫都具有良好的驱杀效果。由于伊维菌素具有用药剂量小、抗虫效果好的特点,随着城镇宠物犬和农户厂矿看护犬养殖规模的扩大,犬寄生虫病感染愈来愈引起人们的重视。伊维菌素作为防治犬体内外寄生虫病的首选药物,在兽医临床上得到了广泛应用。但不合理地使用本品,导致犬发生依维菌素中毒的报道时有出现。本文通过浅析伊维菌素中毒的机理及解救措施,以此引起广大兽医人员在使用伊维菌素时的高度重视。     

犬伊维菌素中毒病例简析

伊维菌素是微生物阿佛曼链霉菌经发酵后产生的半合成大环内酯类多组分抗生素,属于高效、广谱、低毒抗寄生虫药物,与其他的抗寄生虫药无交叉耐药性,是目前动物抗寄生虫药物中效果最好的一种。此种药物杀虫机理主要是能够干扰寄生虫神经生理活动,通过刺激虫体释放出来Y-氨基酸（CA—BA）,从而阻断运动神经信号的传递过程,使虫体肌肉细胞麻痹而致死。对于犬类的疥螨、蠕形螨等体内外寄生虫,都具有较好的治疗作用。但由于伊维菌素的治疗量和中毒剂量很接近,容易引起犬出现中毒。如果两次注射时间相距时间太近,也可能造成积累性中毒。     

大熊猫伊维菌素中毒性休克

3只圈养大熊猫在按正常剂量口服伊维菌素(Ivermectin)进行常规体内外寄生虫病预防时突然发生中毒性休克反应,临床主要表现为:全身松软无力、可视粘膜苍白、四肢冰凉伴阵发性痉挛、呼吸微弱浅表、心率缓慢伴节律不齐、眼球深陷、瞳孔缩小至针尖样大小、四肢对疼痛刺激无应答。根据休克性疾病的发生发展机理采取了抗休克治疗措施,3只大熊猫在分别经过长达65 h、56 h和45 h连续不问断的综合抢救措施后最终得以康复。不仅对大熊猫伊维菌素中毒性休克的临床表现和抢救措施进行了简要描述,并对休克的发生原因进行了相关分析,最终认为:大熊猫口服伊维菌素后发生的中毒性休克与有机磷中毒无关,也与类似于柯利牧羊犬的多药拮抗蛋白(MDR)基因缺陷无关,但极可能与某种未知寄生虫感染相关。     

犬伊维菌素中毒的解救

正伊维菌素是驱杀犬体内线虫和体外寄生虫的首选药物,有时在临床上因为药量过大或短时间内重复用药而造成犬伊维菌素中毒。前几天笔者接诊了一例斗牛犬伊维菌素中毒的病例,经过治疗已痊愈,笔者将诊疗过程加以总结,供大家参考。1临床症状几天前的上午10点,一犬主携一斗牛犬前来应诊,询问得知,犬2.5月龄,体重2.5千克,早上8点左右刚刚口服了驱虫药。笔者观察到,     

Efficacy of avermectin B1 given orally against equine intestinal strongyles and Onchocera microfilaria

Three groups of horses and ponies (N = 13, 13 and 12) were treated with ivermectin paste (0.2 mg/kg p.o.), avermectin B1 solution (0.2 mg/kg p.o.), or fenbendazole suspension (10 mg/kg via nasogastric tube). The avermectin B1 was a 1% solution in a propylene glycolglycerol formal base. Faecal strongyle egg counts were performed before, and 14, 28, 42, 56 and 70 d, after treatment. Full-thickness skin biopsies from the neck, pectoral and umbilical regions were examined for Onchocera microfilaria before treatment, and again 14 and 70 d later. Ivermectin therapy produced a significant (P less than 0.01) decrease in mean strongyle egg counts 14, 28, 42 and 56 d after treatment. Avermectin B1 therapy resulted in significant (P less than 0.01) decreases in mean strongyle egg counts 14, 28 and 42 d after treatment. All horses given ivermectin or avermectin B1 had zero strongyle egg counts 14 and 28 d after treatment. Fenbendazole failed to significantly decrease strongyle egg counts. Both ivermectin and avermectin B1 resulted in zero microfilaria counts in all horses 14 d after treatment. On day 70 the percentage decrease in microfilaria counts were 100% and 99.6% respectively. Fenbendazole failed to significantly decrease microfilaria counts. The oral administration of this formulation of avermectin B1 appeared to be highly efficacious against intestinal strongyles and Onchocera microfilaria. The duration of anti-strongyle activity was, however, significantly (P less than 0.01) shorter than that of ivermectin paste.     

草鱼组织中阿维菌素和伊维菌素的多残留检测

建立了草鱼肌肉（包括皮）中阿维菌素和伊维菌素的多残留检测方法。样品用乙腈提取,正己烷脱脂净化,多拉菌素作内标,经1-甲基咪唑和三氟乙酸酐的乙腈溶液在室温下避光衍生化并在甲醇中水解后,进行HPLC-FLD检测分析。结果表明,阿维菌素和伊维菌素在5~100 ng/g范围内具有良好线性,检测限分别为1.0 ng/g和1.2 ng/g,定量限分别为3.4 ng/g和4.0 ng/g,日间提取回收率分别为96.42%~103.10%和94.23%~101.76%,日内和日间变异系数分别小于4.37%、6.82%和6.73%、8.84%。该方法高效、灵敏、简便,其灵敏度、回收率和重现性等符合有关兽药残留检测要求,可用于草鱼肌肉中阿维菌素和伊维菌素的多残留检测。     

不同药物预防犬恶丝虫病的效果研究

本试验将ELISA检测为恶丝虫病阴性的80头犬随机分为4组,分别用色拉菌素、依维菌素、阿维菌素、左旋咪唑进行预防试验,并对各种药物的效果作比较,结果发现色拉菌素和阿维菌素的预防效果最好,依维菌素次之,左旋咪唑相对最差。     

Possible Anxiolytic Effects of Ivermectin in Rats

Ivermectin, a mixture of 22,23-dihydroavermectin B_1a (80%) and B_1b (20%), is produced by Streptomyces avermectilis, an actinomycete. It is a macrocyclic lactone disaccharide, a member of the avermectin family, and is used as an antiparasitic drug. Previous studies performed in our laboratory showed that doramectin, another avermectin drug, interferes with GABAergic-related behaviours, leading to anxiety and seizures. The objective of the present study was to examine the effects of ivermectin (0.5 and 1.0 mg/kg) on the central nervous system of rats, using behavioural models related to GABAergic neurotransmission. A known anxiolytic drug, diazepam, was used as a positive control. Open field and elevated plus-maze behaviours, as well as conflict behaviour to a conditioned response, were assessed. The effects of ivermectin and diazepam in reversing the anxiety induced by picrotoxin was studied. The protective effects of ivermectin on pentylenetetrazole- and picrotoxin-induced seizures were also investigated. In the open field, 1.0 mg/kg ivermectin decreased locomotion frequency at 15 and 60 min of observation, rearing behaviour showed a biphasic effect at 15 and 30 min and duration of immobility was increased in all sessions after 1.0 mg/kg ivermectin. These data suggest anxiolytic or sedative effects. Ivermectin and diazepam both had a tendency to cause an increase both in the number of entries into the open arms and on the time spent in the open arms of an elevated plus-maze. Picrotoxin on its own reduced the number of entries as well as the time spent in the open arms. Both diazepam and ivermectin reversed these effects of picrotoxin. In conflict behaviour analysis, ivermectin and diazepam gave the classic effect of an anxiolytic drug, reversing the conditioned response to shock. Ivermectin protected rats from the convulsant effects of pentylenetetrazole but not from those of picrotoxin. Thus, ivermectin had the pharmacological profile of an anxiolytic drug with GABAergic properties. The lack of effect on seizures induced by picrotoxin suggests that the action of ivermectin is different from that of the benzodiazepine drugs.     

Is anthelmintic resistance a concern for heartworm control? What can we learn from the human filariasis control programs?

Heartworm prophylaxis is currently largely dependent on the ability of avermectins and milbemycins to arrest the development of third and fourth stages of Dirofilaria immitis for prolonged periods, without producing adulticidal effects. Major control programs, dependent on the activity of ivermectin, are being implemented for human onchocerciasis and lymphatic filariasis. The avermectins and milbemycins act on glutamate-gated and gamma-aminobutyrate-gated chloride channel subunit proteins in nematodes. Ivermectin resistance has been widely described in trichostrongylid nematodes of ruminants. There is evidence that when ivermectin resistance occurs in nematodes, there may be selection on some, but not all of the genes that code for ligand-gated chloride channel subunit proteins as well as on some ABC-transporter genes, whose products may be involved in regulating macrocyclic lactone drug concentrations at receptors, and on some structural protein genes of amphidial neurones. Although ivermectin resistance has not been reported in filarial nematodes, there have recently been reports of suboptimal responses to ivermectin in Onchocerca volvulus. Evidence has been found of ivermectin selection on at least ABC-transporter genes and some neuronal structural protein genes in O. volvulus. To date, there is no evidence of avermectin/milbemycin resistance in D. immitis, also a filarial nematode. Chemotherapy against trichostrongylids of animals, human filariae, and D. immitis, relies on avermectins or milbemycins. However, control involves targeting different stages or processes in the nematode life cycles, different control strategies, different proportions of the nematode population in refugia, and different drug dosage rates. Consideration of the proportion of the D. immitis population normally in refugia, the life cycle stage targeted, and the anthelmintic dosages used suggest that it is unlikely that significant avermectin/milbemycin resistance will be selected in D. immitis with current treatment strategies.     

Neurotoxic effects of ivermectin administration in genetically engineered mice with targeted insertion of the mutated canine ABCB1 gene

Objective-To develop in genetically engineered mice an alternative screening method for evaluation of P-glycoprotein substrate toxicosis in ivermectin-sensitive Collies. Animals-14 wild-type C57BL/6J mice (controls) and 21 genetically engineered mice in which the abcb1a and abcb1b genes were disrupted and the mutated canine ABCB1 gene was inserted. Procedures-Mice were allocated to receive 10 mg of ivermectin/kg via SC injection (n = 30) or a vehicle-only formulation of propylene glycol and glycerol formal (5). Each was observed for clinical signs of toxic effects from 0 to 7 hours following drug administration. Results-After ivermectin administration, considerable differences were observed in drug sensitivity between the 2 types of mice. The genetically engineered mice with the mutated canine ABCB1 gene had signs of severe sensitivity to ivermectin, characterized by progressive lethargy, ataxia, and tremors, whereas the wild-type control mice developed no remarkable effects related to the ivermectin. Conclusions and Clinical Relevance-The ivermectin sensitivity modeled in the transgenic mice closely resembled the lethargy, stupor, disorientation, and loss of coordination observed in ivermectin-sensitive Collies with the ABCB1-1Δ mutation. As such, the model has the potential to facilitate toxicity assessments of certain drugs for dogs that are P-glycoprotein substrates, and it may serve to reduce the use of dogs in avermectin derivative safety studies that are part of the new animal drug approval process.     

Contractile activity and motility responses of the dog heartworm Dirofilaria immitis to classical anthelmintics and other compounds

A variety of compounds including classical anthelmintics and avermectin analogs were screened for their effects on movements of adult heartworms (HW) (Dirofilaria immitis). Contractile activity was measured by tension recording of spontaneous movements of intact HW coil preparations (6 min compound exposure) and motility was evaluated by observation of spontaneous, free movements in culture (3 and 7 days compound exposure). Results for female HW indicated that some compounds caused spastic paralysis of contractile activity and inhibition of motility in culture (bephenium, DL-tetramisole, and pyrantel); some caused only spastic paralysis of contractile activity (methyridine and disophenol); and some caused only inhibition of motility in culture (chlorpromazine, dithiazanine, 1-ethoxycarbonylmethyl-1-methylpyrrolidinium, and 4-methyltropolone). Effects on motility in culture appeared to be lethal. The following compounds lacked effects: amprolium, 2-amino-2-thiazoline, bithionol, bitoscanate, bitriben, hexachlorophene, ivermectin, and 10 H-phenothiazine. A group of avermectin analogs was screened for effects only on motility in culture of both adult female and male HW. Several of the analogs affected motility, but the effects appeared to be non-lethal. Microfilaria release into the culture media was suppressed by two of the analogs (an aglycone and avermectin B2). The HW maintenance system used in the present study facilitated screening of compounds for effects on this parasite.     

The difference in efficacy of ivermectin oral, moxidectin oral and moxidectin injectable formulations against an ivermectin-resistant strain of Trichostrongylus colubriformis in sheep

AIM: To evaluate the efficacy of ivermectin oral, moxidectin oral and moxidectin injectable formulations against an ivermectin-resistant strain of Trichostrongylus colubriformis in sheep. METHODS: Twenty-four mixed breed lambs were infected with 15,000 infective third-stage larvae of an ivermectin-resistant strain of T. colubriformis which had originally been isolated from a goat farm in Northland in 1997. Twenty-six days post infection, the lambs were divided into 3 treatment groups and a control group (n=6 lambs/group). Treatment consisted of either ivermectin oral formulation (0.2 mg/kg), moxidectin oral formulation (0.2 mg/kg), or moxidectin injectable formulation (0.2 mg/kg). Faecal egg counts (FECs) were determined at 0, 3, 5, 7 and 10 days after treatment. All animals were necropsied 12 days after treatment and worm counts were performed. Larval development assays were conducted 24 days post infection. A further 3 lambs were infected with 15,000 infective third-stage larvae of a fully susceptible strain of T. colubriformis for comparative purposes in the larval development assay. The efficacy of the moxidectin injectable formulation was also confirmed in these 3 lambs. RESULTS: The FEC reduction test at day 10 after treatment revealed 62%, 100% and 0% reductions in arithmetic-mean FECs for ivermectin oral, moxidectin oral and moxidectin injectable groups, respectively. The ivermectin oral, moxidectin oral and moxidectin injectable formulations achieved 62%, 98% and 4% reductions in arithmetic-mean worm burdens, respectively. Larval development assays showed resistance ratios for ivermectin of 4:1, avermectin B2 of 2.7:1, ivermectin aglycone of 37:1, moxidectin of 1.4:1, thiabendazole of 14.6:1 and levamisole of 1.8:1. CONCLUSIONS: The moxidectin oral formulation provided a high degree of control against ivermectin-resistant T. colubriformis whereas the moxidectin injectable formulation had very low efficacy. Ivermectin aglycone was the analogue of choice for diagnosis of ivermectin resistance in T. colubriformis in the larval development assay.     

Persistent activity of doramectin and ivermectin against Ascaris suum in experimentally infected pigs.

A study was conducted to investigate the persistent nematocidal activity of two avermectins against experimentally-induced infections of Ascaris suum in swine. Seventy-two nematode-free cross-bred pigs of similar bodyweight were randomly allotted to nine treatment groups of eight pigs each. Eight of the groups were treated with injectable solutions containing 300 microg of doramectin/kg (IM) or 300 microg of ivermectin/kg (SC) either 0 (same day), 7, 14, or 21 days prior to an oral challenge of 50000 embryonated A. suum eggs. The ninth group (control) was challenged in parallel without any avermectin treatment. At 41 or 42 days after challenge, pigs were euthanatized and adult and larval stages of A. suum were collected from the gastrointestinal tract of each pig and counted. Both avermectins significantly (P < 0.0002) reduced nematode counts when given on the day of challenge (0 days prior), and the efficacy was 100% and 97.5% for doramectin and ivermectin, respectively. Doramectin given 7 days prior to challenge significantly (P < 0.0001) reduced nematode counts, and the efficacy was 98.4%. For all other avermectin-treatment groups, nematode counts were not significantly reduced compared to those in control pigs. These data indicated that anthelmintic activity of ivermectin against A. suum persisted for less than 7 days and the activity of doramectin persisted for more than 7, but less than 14 days.     

Moxidectin against ivermectin-resistant nematodes—a global view

SUMMARY Macrocyclic lactone endectocides include two chemically distinct compounds moxidectin, a milbemycin, and ivermectin, an avermectin. The significance of the chemical differences between these compounds in relation to nematode resistance remains to be established. Reported studies indicate that moxidectin at the recommended dose rate of 0.2 mg/kg controls identified strains of nematodes, isolated from sheep and goats, with demonstrated resistance to ivermectin. This reflects the significantly greater potency of moxidectin against the 3 genera of nematodes most commonly involved in anthelmintic resistance, Haemonchus, Ostertagia and Trichostrongylus. Moxidectin, in recommended strategic treatment programmes, should reduce the risk of further development of resistance to the macrocylic lactone endectocides.