A female red-eared terrapin was presented for active nesting behaviour, interrupted by an acute onset of weakness of two weeks of duration. Diet and husbandry were optimal. On examination the patient was alert, body condition was good, and eggs were palpated through the inguinal fossa. Radiographic survey showed multiple metallic densities in the stomach, and normally calcified eggs in the coelomic cavity. Further questioning revealed that a thermometer containing lead pellets had been broken two weeks ago in the enclosure.
Hemogram results were within normal limits and no RBC morphologic changes were observed. Blood lead level was 851 ug/dl.
A diagnosis of lead intoxication and egg retention was made. Chelation therapy was started with CaEDTA 30 mg/Kg IM sid 5 days, off 4 days, and repeated 5 days. Cisapride 1mg/kg PO sid was administered to speed the passage of lead. Nesting sites were also provided.
On day 14 blood lead level had decreased to 438 ug/dl, but radiographic survey didn't show any movement of lead particles or changes in egg calcification. Gastric lavage and endoscopic retrieval of lead were unsuccessful, so medical treatment was continued. The patient improved slowly over the next month, but the owner did not allow further blood tests. Radiography on day 41 still didn't reveal movement of lead pellets but on day 102 the eggs were delivered successfully and radiography showed complete elimination of both lead particles and eggs. The patient has remained clinically healthy for the next six months.
Anecdotal cases of lead intoxication in reptiles have been reported, but only two cases have been published in which blood lead concentration has been measured. Therefore, information on this condition in reptiles is scarce.
CaEDTA pharmacokinetic data for reptiles is not available, so accepted avian protocols were applied in this patient, and resulted both safe and successful to lower blood lead levels. Lead can be sequestered in eggshells and contents, but it was not considered a likely cause of blood lead level reduction in this case, because egg development and calcification were complete by the time of presentation.
In most species blood lead levels over 60 ug/dl are considered a strong evidence of lead toxicosis. The concentration found initially in our patient (851 ug/dl) was very high compared to the level reported in an intoxicated snapping turtle (360 ug/dl), and to what is usual in most intoxication cases.
In this case, the slow gastrointestinal passage of lead particles and the retention of eggs were both compatible with the neuromuscular disfunction shown by lead intoxicated patients. Hypocalcemia could not be ruled out as a contributing factor to egg retention, because more extensive analysis were not allowed by the owner, but optimal husbandry and bone conformation, did not suggest this was a strong possibility.
Severity of clinical signs associated to lead poisoning is variable, and depends on numerous factors such as duration and amount of exposure, age and species. It is remarkable the relatively slight clinical signs displayed by this patient considering the high blood lead concentration detected. It is possible that red-eared terrapins are particularly resistant to lead poisoning.
Study of further cases is needed in order to clearly establish the particularities of lead poisoning in reptilian patients.