Renal pathology in reptiles

EVALUATION OF MORTALITY CAUSES AND PREVALENCE OF RENAL LESIONS IN ZOO-HOUSED CHAMELEONS: 2011-2022

Of the 202 species of Chamaeleonidae, 38.6% are globally threatened. Currently, nearly a thousand individual chameleons from 36 different species are kept in zoological institutions worldwide. The objectives of this study were to assess the main mortality causes of chameleons in zoological institutions, the prevalence of renal lesions at necropsy, and the environmental factors associated with renal lesions. An online survey was sent to 245 zoological institutions worldwide to collect information about species and sex distribution, necropsy results, and husbandry parameters. Necropsy reports of the last 10 yr were requested from participating institutions (n = 65) when available. Mortality causes were classified into three categories (open diagnosis, infectious, and noninfectious), and noninfectious causes were further subdivided into seven categories (renal, reproductive, myoarthroskeletal, digestive, ophthalmologic, denutrition/multisystemic, and neoplastic). The prevalence of renal lesions was recorded. Multiple linear regression models were used with the prevalence of renal diseases as the dependent variable, and exhibit minimum and maximum hygrometry; exhibit highest and coolest temperature; as well as minimum, mean, and maximum hygrometry of the geographical area as independent variables, combining all chameleon species with similar environmental requirements. Results were obtained for 14 species (n = 412 individuals). The main mortality causes were infectious (46.8%), noninfectious renal (11.4%), and noninfectious reproductive (10.7%) diseases, with all cases of fatal reproductive diseases reported in females. Of the individuals that underwent renal histopathology, 41.7% displayed renal lesions. There was a tendency towards higher renal lesion prevalence in zoos located in areas with lower mean hygrometry (P = 0.05). Further research studies about infectious, renal, and reproductive diseases of Chamaeleonidae are warranted.

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.

Urothelial carcinoma in a Russian tortoise (Testudohorsfieldii)

An adult female Russian tortoise (Testudo horsfieldii) was admitted to a veterinary clinic with a 1-week history of anorexia and lethargy. Physical examination revealed significant dehydration and generalized dysecdysis. Blood parameters were all within species-reported limits. Radiography revealed an increased amount of soft tissue opacity within the coelomic cavity and a distinct loss of serosal detail. A large cavitated mass was detected ultrasonographically in the right coelom and a tentative diagnosis of kidney pathology was made. Using computed tomography and magnetic resonance imaging, a partly mineralized heterogeneous mass was seen in the right coelom. After stabilization, a transplastron coeliotomy was performed. A 7 × 5 cm mass, including associated cysts, was removed. The tortoise died 8 h postoperatively and post-mortem examination revealed a urothelial carcinoma arising from the renal pelvis. To the authors' knowledge, this is the first report in a tortoise of urothelial carcinoma, which has rarely been reported in reptiles.

[Diagnosis of kidney diseases in European tortoises (Testudo spp.)]

The diagnosis of kidney diseases in tortoises is only possible to a very limited extent on the basis of the general examination due to the development of unspecific disease symptoms. Extensive additional examinations are required to confirm the diagnosis. In addition to blood and urine tests, imaging techniques such as X-ray, computed tomography and MRI are suitable for visualizing the skeletal and organ systems, while additional samples can be taken during an endoscopic examination. There are clear species-specific differences with regard to the reference values of the laboratory parameters, which are in part significantly influenced by environmental influences, the seasons or even gender. It can also be seen that kidney diseases in tortoises kept in captivity are usually very advanced at the time of diagnosis, since these animals, like reptiles in general, show a pronounced lack of symptoms. Annual checks by a veterinarian specialized in reptiles can help to detect diseases at an early stage.

Identification of Uric Acid Crystals Accumulation in Human and Animal Tissues Using Combined Morphological and Raman Spectroscopy Analysis

Gout is a metabolic condition, common to animals and humans, issuing from the excessive accumulation of end products of proteins degradation. In this study, histopathological and cytological examinations, combined with Raman spectroscopy, have been performed to investigate tissue samples from reptiles, chickens, and humans, presenting lesions produced by uric acid accumulation. As a result of classic processing and staining techniques commonly used in the anatomopathological diagnosis, uric acid crystals lose their structural characteristics, thus making difficult a precise diagnostic. Therefore, complementary diagnostic methods, such as Raman spectroscopy, are needed. This study compares from several perspectives the above mentioned diagnostic methods, concluding that Raman spectroscopy provides highlights in the diagnosis of gout in humans and animals, also adding useful information to differential diagnosis of lesions.

Diseases of the Reptile Renal System

Renal disease accounts for a considerable amount of morbidity and mortality in reptiles, in part owing to inadequate husbandry practices, such as inappropriate temperature, humidity, and access to water. Inappropriate husbandry practices may lead to subclinical dehydration that can specifically impact the renal system, which relies on vascular perfusion to function. This article aims to highlight urinary pathophysiology and summarize infectious and noninfectious causes of renal disease in reptiles as a guide for differential diagnoses to consider during clinical evaluation.

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.

Approach to Reptile Emergency Medicine

This article summarizes the physiology and anatomy of reptiles, highlighting points relevant for emergency room veterinarians. Other systems, such as the endocrine and immune systems, have not been covered. The many other aspects of reptile species variation are too numerous to be covered. This article provides an overview but encourages clinicians to seek additional species-specific information to better medically diagnose and treat their reptile patients.

A retrospective study of mortality in varanid lizards (Reptilia: Squamata: Varanidae) at the Bronx Zoo: implications for husbandry and reproductive management in zoos

Varanid lizards have been maintained in zoological parks for more than a century, yet few studies to date have attempted to pinpoint significant health issues affecting their management or areas of captive husbandry that are in need of improvement. In an effort to identify and better understand some of the husbandry-related challenges and health issues specifically affecting varanids in zoos, this study examined mortality in 16 species maintained at the Bronx Zoo between 1968 and 2009. Out of 108 records reviewed, complete necropsy reports were available for 85 individuals. Infection-related processes including bacterial (15.3%), protozoal (12.9%), nematode (9.4%), and fungal (3.5%) infections accounted for the greatest number of deaths (47.1%). Noninfectious diseases including female reproductive disorders (7.1%), neoplasia (7.1%), gout (10.8%), and hemipenal prolapse (1.3%) accounted for 29.4% of deaths. Multiple disease agents were responsible for 5.9% of deaths, and a cause for death could not be determined for 17.7% of individuals. Reproductive complications accounted for 11.5% of female deaths, but were identified in 23.1% of females. Although not necessarily the cause for death, gout was present in 18.8% of individuals. Differences in mortality between species, genders, and origin (captive-bred vs. wild-caught) were also evaluated. The results of this study corroborate earlier findings that identify bacterial infections, neoplasia, female reproductive disorders, gout, and endoparasitism as major sources of mortality in captive varanids. In light of these results, we discuss potential etiologies and offer recommendations for improving captive management practices in zoos.