| Typical active ingredients for rat poisons are are: | | | | Platelets have on their surface binding sites for |
| brodificoum, diphacinone, warfarin, bromadiolone, | | | | coagulation proteins, which also circulate normally |
| and others. Most of these products include green | | | | in inactive forms. These coagulation proteins must |
| dyes for a characteristic appearance; however, | | | | be activated in order to produce fibrin. There are |
| dogs and cats have poor color vision and to them | | | | two ways to do this: a so-called intrinsic pathway |
| these pellets may look like kibbled pet food. | | | | and a so-called extrinsic pathway. There are |
| Anticoagulant rodenticides do not produce signs of | | | | twelve clotting factors involved between these |
| poisoning for several days after the toxic dose | | | | two pathways and we will not confuse you by |
| has been consumed. Anticoagulant rodenticides | | | | reviewing these steps but suffice it to say that |
| cause internal bleeding. A poisoning victim will show | | | | calcium is one of the factors as are 4 enzymes |
| weakness and pallor but bleeding will likely not be | | | | called serine proteases. It is the serine proteases |
| obvious externally. | | | | which are relevant to rat poisoning. The end |
| To understand what these poisons do, it is | | | | product of these pathways is protein fiber called |
| necessary to have some understanding of how | | | | fibrin which binds the platelets and serves as a |
| blood clots. A blood vessel is sort of like a pipe | | | | scaffolding for the permanent healing of the |
| carrying rapidly flowing blood along its path. The | | | | vessel tear. |
| pipe is lined by smooth flat cells called endothelial | | | | Anticoagulant (containing a chemical called |
| cells which facilitate the smooth flow of the blood. | | | | warfarin) impairs the creation of one of the |
| If the pipe breaks, the structure of the pipe | | | | significant blood clotting factors, prothrombin. |
| below the lining is exposed to the flowing blood | | | | Vitamin K is an important factor in the synthesis |
| inside. From there the sequence of events is as | | | | of prothrombin clotting factors in the blood. |
| follows: | | | | Because of this, Vitamin K is considered an |
| The blood vessel automatically constricts and | | | | antidote for warfarin overdose. If a child or pet |
| spasms. This restricts the blood flowing to the | | | | inadvertently consumes a warfarin-based |
| damaged area and helps minimize blood loss. | | | | rodenticide, the usual treatment is injections of |
| The exposed pipe attracts circulating platelets, | | | | Vitamin K. This is simplified greatly because the |
| cloud-like cells that circulate ready to assist in | | | | actual effects of the warfarin can be measured |
| clotting should the need arise. Platelets clump | | | | fairly accurately by measuring the blood clotting |
| together over the tear in the blood vessel | | | | rate. This prothrombin clotting time or protime |
| forming a plug within the first 5 minutes of the | | | | measurement is necessary for anyone on |
| injury. This is all a good thing but the platelets will | | | | warfarin prophylaxis therapy. Tests may be done |
| stay in place unless a substance called fibrin can | | | | as frequently as daily to as infrequently as |
| be made to bind them. | | | | monthly. |