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Volume 27 | Issue 3 Article 4

1965 Thallium Poisoning in the Dog Virginia L. Marshall Iowa State University

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Recommended Citation Marshall, Virginia L. (1965) "Thallium Poisoning in the Dog," Iowa State University Veterinarian: Vol. 27 : Iss. 3 , Article 4. Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol27/iss3/4

This Article is brought to you for free and open access by the Journals at Iowa State University Digital Repository. It has been accepted for inclusion in Iowa State University Veterinarian by an authorized editor of Iowa State University Digital Repository. For more information, please contact [email protected]. Thallium Poisoning In• the Dog

by Virginia L. Marshall, B.S., M.S.*

Thallium compounds have been used lous sulfate and acetate, have many ad­ as rodenticides for many years. Reports vantages over other compounds when used of poisoning of domestic animals by thal­ as a rodenticide. Since they are odorless lium were published as early as 1920. The and tasteless, they 'are more readily taken general use of these compounds by pest by rodents than are those with an odor or control companies, and their availability distinctive taste. Rats in particular are to the general public has increased the known to avoid baits containing rapid-act­ frequency of accidental poisoning of do­ ing poisons such as strychnine. Since thal­ mestic animals. lium salts rarely cause death in less than Thallium, a heavy metal, has an atomic 3-5 days after ingestion, rats do not as­ weight similar to both lead and mercury, sociate the death of other rats with the and has many characteristics in common consumption of the bait. The main disad­ with these metals. As is true of many vantage of thallium as a rodenticide is its other heavy metals, thallium is a general toxicity to all other mammals. Since cellular poison, although its most promi­ heavy metals are not metabolized, do­ nent effects are in those cells localized in mestic animals can be poisoned by con­ a few areas of the body. Following in­ suming rats which have died from thal­ gestion, thallium is rapidly distributed lium poisoning, as well as by direct con­ throughout the body, being found in all sumption of thallium baits. tissues and body fluids. It is excreted in urine, feces, and milk. Using spectrogra­ SYMPTOMS phic methods, thallium has been detected The symptoms of thallium toxicity in in the urine of dogs less than 24 hours the dog may present a confusing diag­ after ingestion. Peak blood levels are found nostic picture for the clinician. POisoning within a few hours after oral administra­ can generally be classed as per-acute, tion of thallium compounds. Like lead, acute, or chronic, although these terms thallium is very slowly eliminated by the can also be very misleading. It is very body. It has been found present in the rare when any symptoms are observed urine months after administration. As less than 24 hours after ingestion of thal­ might be expected, thallium can be a lium. In chronic cases, the onset of symp­ cumulative poison; several individually toms may be delayed for 3-5 days or non-lethal doses administered over a period more. of time, can result in the accumulation of In per-acute poisoning, severe gastro­ a lethal quantity in the tissues. enteric signs, including vomiting, severe Thallium compounds, particularly thal- abdominal pain, loss of appetite, and di­ arrhea are observed (7,8). Occasionally a hemorrhagic enteritis will follow. Dyspnea • Mrs. Marshall is an assistant professor in the Veterinary Diagnotic Laboratory. is also seen, with death occurring in 2-5

Issue, No.3, 1965 115 days. In some cases, motor paralysis and/ lowing hair loss, the skin becomes dry or trembling may also be observed. Some and crusted. Necrosis of the superficial authors have reported that the body tem­ layers may also appear. Necrosis is some­ perature remains normal unless secondary times preceeded by a reddening of the infection is present (6). In experimental skin, particularly in areas subject to fric­ cases of per-acute thallium toxicity in tion. Should the animal survive, the dogs, the body temperature was elevated normal growth of hair will resume, al­ 36-40 hours after ingestion to 108° F in though several months delay may be in­ one dog, 103° F in a second, and 102.8° F volved. These gross skin changes can be in a third dog. The temperatures remained found in other disorders, and it is often at this level until death, which followed advisable to eliminate the possibility of in­ within 3 days (1). fectious or parasitic agents. The course of the acute form is some­ what slower than the per-acute, lasting POSTMORTEM FINDINGS from one to several weeks. As with the The necropsy findings in thallium in­ per-acute form, gastroenteric disturbances toxication vary with the severity of dosage are usually the first symptoms observed. and length of illness. In per-acute cases, This is combined with, or followed by, severe hemorrhagic gastroenteritis may be muscular tremors and evidence of pain in the only finding, although inflammation of the extremities. Conjunctivitis and injec­ the respiratory mucosa occasionally oc­ tion of the sclera are observed in many curs. cases. The oral mucous membranes are In acute cases lesions in other organs frequently congested, often becoming are observed. Congestion and hemorrhage brick-red or mahogany in color. Bronchitis may occur in many organs including and pneumonia may also develop. If death spleen, kidneys, and heart. Fatty degen­ is delayed, severe motor disturbances and eration and necrosis of the liver has also blindness occur. Even if the acute stage been described. Petechial. hemorrhage, is survived, death may occur later. Ani­ perivascular cuffing and demyelination oc­ mals which survive the initial effects of cur frequently in the brain. In the dog, the thallium may succumb to secondary the cutaneous histopathology of thallium bacterial infections or to extensive renal intoxication is unlike any other cutaneous damage incurred during the process of ex­ reaction reported in the literature. Exam­ cretion of the thallium. ination of sections taken from erythema­ The signs of chronic poisoning are simi­ tous areas reveals hyperkeratosis, moder­ lar to those of the acute form, but are gen­ ate parakeratosis, hyperemia, and hyaline erally milder and of longer duration. The changes. The cutaneous histopathology of symptoms described perviously are not in­ thallium poisoning has been. described in dicative of thallium poisoning alone, but great detail by Schwartzman and Kirsch­ are similar to those of most heavy metal baum (5). poisonings. Perhaps the most characteristic Analysis of tissues from an animal with signs of thallium intoxication in the acute thallium poisoning has shown the presence form are the congested sclera and brick-red of thallium in all tissues. For the labora­ oral mucous membranes while the hair and tory diagnosis of a suspected case of thal­ skin changes are most characteristic in lium intoxication there are several meth­ the chronic form, although they may take ods available for analysis of body fluids. from one to three weeks to develop. The In practice, testing of urine by any of the most obvious initial change is the rapid "quick tests" (2, 3) available has been loss of hair beginning in the areas subject shown to be quite reliable. One such test, to friction and progressng at times over described by Gabriel and Dubin (2), re­ the entire body. Close examination will quires a minimum of time and can be often show this change first in the in­ routinely used by a practictioner with a terdigital and axillary spaces where the minimum of expense for chemicals and skin may become dry and cracked. Fol- equipment.

116 Iowa State University Veterinarian TREATMENT alone. The most characteristic clinical Many approaches have been tried for changes observed are injection of the sclera the treatment of thallium pOisoning. If and reddening of oral mucous membranes used within one to two hours after inges­ in acute cases and alopecia and skin tion of the poison, gastric lavage with 1 % changes in chronic cases. The detection of sodium iodide solution has been shown thallium in .the urine of suspected cases of to be beneficial. Treatment with sodium poisoning by one of the "quick tests" avail­ thiosulfate, BAL or calcium EDTA has able has been shown to be one of the best been of little benefit. Diphenylthiocar­ diagnostic aids. A specific, effective anti­ bazone has been used for treatment of dote for thallium toxicity is lacking, al­ thallium poisoning with somewhat more though diphenylthiocarbazone has shown success than other therapeutic agents. promising results in some cases. Since this compound has resulted in a serious systemic zinc loss, it must be used REFERENCES with utmost caution. Treatment of acute 1. Buck. w. B .• Personal Communication. cases with 70 mg-. diphenythiocarbazonej 2. Gabriel. K. L. & Dubin. S .• A Method for the De­ tection of Thallium in Canine Urine, Am. Vet. kg body weight three times daily, with 2-6 Med. Assoc. Journa1143:722, 1963. gms. potassium chloride daily has been 3. Garner, R. J., Veterinary Toxicology, William & suggested as being satisfactory (4). In Wilkins Co .• Baltimore p 124-125. 1961. 4. Mather. G. W. & Low. D. G .• Thallium Intoxication chronic cases it may be inadvisable to ad­ in Dogs, Jour. Am. Vet. Med. Assoc., 137:544. minister such high doses since it may 1960. 5. Schwartzman. R. M. & Kirschbaum. J. 0., The cause the rapid transfer of thallium from Cutaneous Histopathology of Thallium Poisoning. the tissues into the blood stream and vital Jour. Investigative Dermatology 39: 169, 1962. 6. Skelley, J. R. & Gabriel, K. L •• Thallium Intoxica­ organs resulting in acute thallium toxicity. tion in the Dog, Annals; N. Y. Acad. Sci., 3:612, 1964. SUMMARY 7. RadelefF, R. D.. Veterinary Toxicology, Lea & Thallium poisoning in dogs is a disorder Febiger. Philadelphia, p 161-162. 1964. S. Wildson. J. E., Thallotoxicosis, Jour. Am. Vet. which is difficult to diagnose by symptoms Med. Assoc., 139:1116,1961.

a case report: Thallium Toxicity In• the Dog

by Marvin Farley

HISTORY CLINICAL SIGNS A two and one-half year old spayed fe­ The patient was treated as an inpatient. male miniature schnauzer was presented Large, multiple, focal areas of erythema to the university clinic for treatment. The were noted on the dog's skin. Hair could owner reported that the dog had been easily be pulled out of the skin in tufts. losing hair for the past four days. No Physical examination revealed no other other history was available and the ani­ externally detectable clinical signs, al­ mal had no other observable signs. though skin sensitivity seemed to increase • Mr. Farley is a senior student in the College of Veterinary Medicine at Iowa State University. over a period of five to seven days.

Issue, No.3, 1965 117