Tehran University of Medical Sciences Journal of Arthropod-Borne Diseases 2322-1984 11 1 2017 04 18 42 49 EN Elham Valikhanfard-Zanjani Department of Biology, Faculty of Sciences, Kharazmi University, Tehran, Iran Abbas Zare-Mirakabadi Department of Venomous Animals and Antivenom Production, Razi Vaccine and Serum Research Institute, Karaj, Iran Ehsan Zayerzadeh Department of Biology, Faculty of Food Industry and Agriculture, Standard Research Institute, Karaj, Iran 2016 04 18 2016 04 18 Background: Nowadays use of specific antivenin for latrodectism is considered as the most effective treatment in the world. This study was undertaken to investigate the efficacy of specific antivenom against histopathological complications caused by Latrodectus dahli venom on liver, heart and kidneys tissues within 72 h. Methods: Two groups were selected, each one contained 6 male New Zealand rabbits weighing 2±0.5 kg. The ani­mals were anesthetized with 0.5 ml ketamine and 0.5 ml xylazine by intramuscular route. The L. dahli venom (0.5 mg/kg) was injected subcutaneously to both the groups. The second group of rabbits 24 h after the venom injection received specific antivenom by intravenous route. Seventy-two hours after the venom and antivenom injections, the rabbits were dissected to obtain heart, liver and kidney tissues. The tissues were stained by hematoxylin and eosin stains and histopathological studies were examined by optical microscope. Results: In group one, the venom induced myocytolysis, myocarditis, coagulation necrosis in the heart tissue and the liver tissue showed central vein congestion, congested vessels, dilated sinusoids and inflammation. However, no significant histopathological complications were observed in kidney tissues. In the second group, antivenom injec­tion greatly prevented escalation of the complications on foresaid tissues. Conclusion: Latrodectus dahli venom induces histopathological complications on vital organs. Specific antivenom injection, 24 h after the venom injection, could protect the tissues from incidence and intensification of histopatho­logical complications. Future studies in human beings should be conducted to assess the protection against the spe­cific-Latrodectus antivenin. https://jad.tums.ac.ir/index.php/jad/article/view/427 https://jad.tums.ac.ir/index.php/jad/article/download/427/311