VLD 421: Veterinary Clinical Biochemistry and Laboratory Diagnosis-II (0+1)

RODENTICIDES

Appreciation and Differentiation of Symptoms caused by Rodenticides

1	Zinc phosphide	Clinical signs are usually acute in nature, occurring within 0.5-4 hours of ingestion. These include vomiting ,often bloody vomition, depression, tremors and abdominal pain. In dogs, aimless running (mad or dog running), howling, barking, yelping, snapping of teeth, tremors, salivation. Colic is seen in horses and whereas bloat occurs in cattle. Others signs include ataxia, weakness, prostration. Dyspnoea, gasping, struggling, convulsions or hyperesthesia, increase in body temperature and coma leading to death, which occurs in 3- 48 hours.
2	Warfarin and Congeners	Clinical signs have late onset of action ( 1-3 days) after ingestion of toxicant. It includes massive hemorrhages, blood discharge from body orifices, visible haematomas under skin and around joints, purpura, dyspnoea, weakness and signs of shock. Capillary hemorrhages may occur in absence of trauma. Hemorrhages may be internal or external. Depending on the site of hemorrhage, clinical signs may vary. Hemorrhages in brain, spinal cord and subdural space are reflected as ataxia, paresis, depression, convulsions, etc. Placental hemorrhages may cause abortion. Periarticular or intra articular hemorrhages can cause lameness, joint swelling and pain. Sudden internal hemorrhage can lead to acute anemia, shock and cyanosis. Animals may be found dead with no premonitory signs.
3	Alphanaphthylthiourea ( ANTU)	The intoxicated animals show gastric disorders and respiratory distress. There is labored breathing and cyanosis. Auscultation of chest reveals bubbly respiratory sounds. In later stages, white foam is usually discharged from the nostrils and the oral cavity. The pulse is usually accelerated and heart beats are difficult to determine, owing to hydropericardium. As asphyxiation proceeds, coma ensures and terminal clonic convulsions may occur. Pulmonary edema and circulatory failure usually kill the animals with in 12 hours.
4	Sodium Fluoroacetate and Sodium Fluorocetamide	Signs are most prominent in dogs. Initial signs include restlessness, hyperirritability and vomition. Advanced signs include repetitive urination, defecation, tenesmus, dyspnoea and frothing. The dogs periodically experience wild running, barking etc. These are followed by intermittent tonic-clonic seizures. Cardiac arrest accompanied by sudden death is the prominent feature of Fluoroacetate toxicosis in horses and ruminants. The overall course is rapid and affected animals die within hours after signs appear.
5	Strychnine	After ingestion of strychnine first signs appear with in 0.5 to 2 hours which include restlessness, muscular twitching and neck stiffness. Later convulsions occur with intervening periods of relaxation which becomes progressively shorter. Advanced signs include spontaneous and nearly continuous tonic seizures with marked rigidity sometimes known as ‘saw horse stance’ (Ophisthotonus condition). Death mainly occurs from suffocation due to spasms of the respiratory muscles or paralysis of the respiratory center.