Use of Blood Lactate in Assessment of Manual Capture Techniques of Zoo-Housed Crocodilians

Abstract

Species-specific welfare indicators are important in promoting positive welfare for zoo animals. Reptiles are a notoriously understudied group in regards to behavior, welfare needs, and husbandry requirements. Using opportunistically obtained samples, we evaluated how blood lactate is affected by variation in manual capture and restraint in crocodilians. Lactate is an indicator of anerobic metabolism in reptiles. It offers a relatively simple and indirect way to assess physiological stress. Determining the best way to reduce struggling during capture and associated stress is of great importance to these species’ overall welfare. Blood samples (N = 53) were collected from 10 different species of crocodilians. It was found that age class was a significant predictor variable of lactate levels after capture, and longer handling time seemed to cause an increase in lactate. Finally, draining enclosure pools for a small number of the captures was associated with higher lactate levels compared to other capture factors that were recorded. This study showed that welfare of captive crocodilians could be improved by shortening the duration of physical restraint events when possible. Developing objective measures of welfare and establishing baseline recommendations for care and handling of crocodilians will ultimately promote and improve their wellbeing, along with that of other understudied reptiles in zoos.

Hand grab or noose pole? Evaluating the least stressful practice for capture of endangered Turks and Caicos Rock Iguanas Cyclura carinata

“…Other studies in reptiles have shown that lactate concentration values are generally positively correlated with time since capture or since the onset of an activity burst ( Bartholomew, Bennet & Dawson, 1976 ; Bennet, Dawson & Bartholomew, 1975 ; Cerreta et al, 2020 ; Molinaro et al, 2022 ). Our study shows that lactate concentration in Cyclura carinata seems to reach a plateau approximately 15 min after capture.…”

“…As a result, short and intense bursts of activity can dramatically increase the lactate concentration in the blood stream and other tissues ( Pang & Boysen, 2007 ). A diagnostic approach that uses blood lactate concentration level to infer stress level while sampling wild and captive individuals has been developed and used in mammals, but numerous studies have now shown its utility in reptiles as well ( Klein et al, 2020 ; Mones et al, 2021 ; Molinaro et al, 2022 ).…”

“…A similar pattern of lactate accumulation has been observed in the desert iguana, Dipsosaurus dorsalis , after 15 s of running at 1 m/s ( Donovan & Gleeson, 2006 ). A short and intense burst of activity is what is experienced by many reptile species during routine and Institutional Animal Care and Use Committee (IACUC) approved procedures for field sampling and restraining ( Goessling & Mendonça, 2020 ; Klein et al, 2020 ; Molinaro et al, 2022 ). For example, Mones et al (2021) conducted a study on loggerhead sea turtles ( Caretta caretta) comparing the performance of two point-of-care analyzers after manually restraining individuals.…”

Histopathological Findings Associated with Capture Myopathy in Persian Onager (Equus hemionus onager)

“…In this regard, due to the high value of wildlife animals and the rising trend of trading them worldwide, the loss of even a single species might have huge conservation or financial consequences. Furthermore, CM has affected wildlife more than any other disease cause in the previous fifty years (Molinaro et al 2022). As a result, the little economic impact of the death of wildlife animals due to CM emphasizes the need to learn more about the origins, treatments and prevention of this lethal disease.…”

“…In more severe conditions, the animals may develop lame or stiff limbs, lose their appetite, constipate, and seem weak or sluggish. When an animal displays these signs, its survival chances decrease (Molinaro et al 2022). The present study aimed to investigate the clinical and histopathological findings of the ataxic myoglobinuric syndrome in Persian Onagers, a rare case of capture myopathy that occurred due to unavoidable events when handling captured animals at the zoo.…”