Evaluation of the use of technetium Tc 99m diethylenetriamine pentaacetic acid and technetium Tc 99m dimercaptosuccinic acid for scintigraphic imaging of the kidneys in green iguanas (Iguana iguana)

Urine Output Monitoring and Acute Kidney Injury in Non-mammalian Exotic Animal Critical Care

Acute kidney injury (AKI) is a sudden, severe decrease in kidney function which can occur in any species. There are various causes of AKI, some of which are seen in domestic species and some that are unique to birds, reptiles, and amphibians. These species present unique challenges with AKI management, such as differences in anatomy and physiology, intravenous and urinary catheterization, repeated blood sampling, and their tendency to present in advanced states of illness. This article will discuss AKI, diagnosis, treatment, and prognosis for non-mammalian exotic species.

Radionuclide, magnetic resonance and computed tomography imaging in European round back slugs (Arionidae) and leopard slugs (Limacidae)

Other than in animal models of human disease, little functional imaging has been performed in most of the animal world. The aim of this study was to explore the functional anatomy of the European round back slug (Arionidae) and leopard slug (Limacidae) and to establish an imaging protocol for comparative species study. Radionuclide images with single photon emission computed tomography (SPECT) and positron emission tomography (PET) were obtained after injections of standard clinical radiopharmaceuticals ^99mtechnetium dicarboxypropane diphosphonate (bone scintigraphy), ^99mtechnetium mercaptoacetyltriglycine (kidney function), ^99mtechnetium diethylenetriaminepentaacetic acid (kidney function), ^99mtechnetium pertechnetate (mediated by the sodium-iodide symporter), ^99mtechnetium sestamibi (cardiac scintigraphy) or ¹⁸F-fluoro-deoxyglucose (glucose metabolism) in combination with magnetic resonance imaging (MRI) and computed tomography (CT) for uptake anatomic definition. Images were compared with anatomic drawings for the Arionidae species. Additionally, organ uptake data was determined for a description of slug functional anatomy in comparison to human tracer biodistribution patterns identifying the heart, the open circulatory anatomy, calcified shell remnant, renal structure (nephridium), liver (digestive gland) and intestine. The results show the detailed functional anatomy of Arionidae and Limacidae, and describe an in vivo whole-body imaging procedure for invertebrate species.

Clinical Management of Reptile Renal Disease

Renal disease is one of the most common medical conditions encountered in captive reptiles. In most cases, signs of disease are nonspecific and often not present until the condition is advanced. Many factors contribute to the development of renal disease, and the etiology often is multifactorial. Diagnosis of renal disease by traditional methods used in small animals is not as straightforward as in reptiles; often many tests may be needed to reach a firm diagnosis. Prevention is preferred to treatment. Understanding the pathophysiology, potential causes, diagnostic tests available, and treatment options is essential for the reptile veterinarian to manage this condition.

COMPARATIVE RENAL DISPOSITION OF CREATINE, AND TECHNETIUM DIAGNOSTIC CONTRAST AGENTS IN THE PIGEON (COLUMBA LIVIA)

Clinical assessment of renal function in avian species often involves the measurement of plasma uric acid and blood urea nitrogen, relatively insensitive markers of renal dysfunction and dehydration. In mammals, endogenous creatinine is widely used as an indicator of renal glomerular dysfunction. However, avian species produce primarily creatine. Here, renal creatine, ^99mTc99-DTPA (diethylenepentaacetic acid, DTPA) and 99mTc-MAG3 (mercaptoacetyl triglycine, MAG₃) renal clearances are characterized in the pigeon avian model by infusing DTPA with inulin and creatine with each tracer and examining the slope of their blood disappearance curves. Clearance curves for inulin and DTPA were parallel, suggesting DTPA is cleared by renal filtration. MAG₃ clearance (slope: -2.74 × 10⁵, r² = 0.97) had a slope almost 10-fold steeper than for DTPA (slope: -6.29 × 10⁴, r² = 0.90), and orders of magnitude steeper than for creatine (slope: -1.4, r² = 1.0). These results suggest that DTPA is cleared by glomerular filtration like inulin, while MAG3 is filtered and actively excreted in a manner similar to mammals. In contrast, creatine is filtered and resorbed, has a larger volume of distribution (V_d), or exhibits a greater blood protein binding, making it more complex as a renal marker, when compared with creatinine handling in mammals. The two radiotracers can be readily adapted for use in birds, inviting both qualitative and semiquantitative functional evaluation of avian renal function for research and clinical purposes. The elimination of creatine appears to be more complex requiring further study.

A fresh look at metabolic bone diseases in reptiles and amphibians

Metabolic bone diseases (MBDs) are a common presenting complaint in reptiles and amphibians to veterinarians; however, understanding of the causes and diagnostic and treatment options is often extrapolated from human or other mammalian medicine models. Although the roles of UV-B, calcium, phosphorus, and cholecalciferol are better understood in some MBDs, there remain many X factors that are not. Likewise, quantitative diagnosis of MBDs has been difficult not only in terms of staging a disease but also regarding whether or not a condition is present. Treatment options also present challenges in corrective husbandry and diet modifications, medication/modality selection, and dosing/regimen parameters.

Preliminary evaluation of 99mTechnetium diethylenetriamine pentaacetic acid, 99mTechnetium dimercaptosuccinic acid, and 99mTechnetium mercaptoacetyltriglycine for renal scintigraphy in corn snakes (Elaphe guttata guttata)

The efficacy of three radiopharmaceuticals, 99mTc-diethylenetriaminepentaacetic acid (99mTc-DTPA), 99mTc-dimercaptosuccinic acid (99mTc-DMSA), and 99mTc-mercaptoacetyltriglycine (99mTc-MAG3), for renal imaging was examined in 16 corn snakes (Elaphe guttata guttata). All snakes received the radiopharmaceutical via an intracardiac injection. The kidneys could not be visualized in the three snakes that received 99mTc-DTPA or in the three snakes that received 99mTc-DMSA, but were well delineated in all 10 snakes receiving 99mTc-MAG3. These snakes were anesthetized and a dynamic frame mode acquisition was obtained for 30 min immediately following injection. A 60 s single static frame mode image was then obtained with the snake in a curled position. Two of the 10 snakes that received 99mTc-MAG3 were removed from further analysis because of suspected pericardial injections. Of the remaining eight snakes, the mean (+/- SD) renal uptake was 25 +/- 9.8% or 24 +/- 9.7%, with or without correction for residual injection site activity, respectively. Correction for remaining radioactivity in the heart does not appear to be necessary if it is less than 10% of the total dose. 99mTc-MAG3 provided consistently high quality images of the kidneys and further studies are warranted to evaluate its sensitivity for detecting decreased function in snakes with renal disease.

Renal diseases of reptiles

Renal disease is one of the most common problems in reptilian medicine. Herbivorous species seem to be more susceptible than carnivores. The causation may be multifactorial, and the signs are often nonspecific. Prevention is preferred to treatment, and a comprehensive health program, which includes quarantine, routine health screens during annual examinations, and necropsy examinations of all animals that die, is desirable.