Reptilian Hearts: The Ultimate Survival Machines That Can Keep Beating Without Oxygen, Brain, or Body

Reptilian Hearts: The Ultimate Survival Machines That Can Keep Beating Without Oxygen, Brain, or Body

Turtles are fascinating creatures that can live for a long time, sometimes even longer than humans. But what happens when they die? Do they stop moving immediately, or do they keep twitching for a while? And what about their hearts? Do they stop beating as soon as the turtle is declared dead, or do they keep pumping blood for hours, days, or even weeks?

In this article, we will explore the amazing phenomenon of reptilian hearts that can keep beating after death, even when separated from the body. We will also look at the reasons behind this phenomenon, such as the slow metabolism, high concentration of ions, and special cardiac tissue of reptiles. We will focus on turtles as an example, but also mention other reptiles that share this trait.

Part 1: How to Tell If a Turtle Is Dead or Alive

Before we dive into the topic of post-mortem heartbeats, we need to address a more basic question: how can we tell if a turtle is dead or alive? This may seem like an easy question, but it is actually quite tricky. Turtles are notoriously difficult to diagnose for death, because they have several adaptations that allow them to survive in harsh conditions and appear lifeless.

One of these adaptations is hibernation. Turtles can lower their body temperature and metabolic rate to conserve energy and survive cold winters. During hibernation, they may bury themselves in mud or sand, or hide under rocks or logs. Their breathing and heartbeat become very slow and faint, and they may not respond to external stimuli. To an inexperienced observer, they may look dead, but they are actually alive and waiting for warmer weather.

Another adaptation is anoxia tolerance. Turtles can survive without oxygen for a long time, thanks to their ability to store glycogen in their liver and muscles, and use anaerobic metabolism to produce energy. They can also reduce their oxygen demand by shutting down non-essential organs and functions. This allows them to stay underwater for hours or even days without coming up for air. Some turtles can even breathe through their cloaca (the opening for excretion and reproduction) or their skin, by absorbing dissolved oxygen from the water. When turtles are exposed to anoxia (lack of oxygen), they may enter a state of torpor (reduced activity and responsiveness), which can also make them look dead.

A third adaptation is decapitation survival. Turtles can survive having their heads cut off for a short period of time, because their brains are not essential for controlling their basic bodily functions. Their spinal cord and peripheral nerves can still send signals to their muscles and organs, allowing them to move and breathe. Their hearts can also keep beating without any input from the brain, thanks to their special cardiac tissue that we will discuss later.

These adaptations make it hard to determine if a turtle is dead or alive by just looking at it. Some signs that may indicate death are:

• Rigor mortis (stiffening of the muscles)
• Putrefaction (decomposition of the body)
• Livor mortis (pooling of blood in the lower parts of the body)
• Algor mortis (cooling of the body)
• Clouding of the eyes
• Absence of reflexes
• Absence of heartbeat

However, these signs are not always reliable or conclusive. Rigor mortis may not occur in cold-blooded animals like turtles, or may be delayed by low temperatures. Putrefaction may also be slowed down by low temperatures or dry environments. Livor mortis may not be visible in turtles with dark shells or skin. Algor mortis may not be significant in ectothermic animals like turtles, whose body temperature depends on the environment. Clouding of the eyes may be caused by dehydration or injury, not necessarily death. Absence of reflexes may be due to hibernation or torpor, not necessarily death. And absence of heartbeat may be due to faintness or irregularity, not necessarily death.

Therefore, to confirm if a turtle is dead or alive, it is necessary to perform a thorough physical examination and use diagnostic tools such as stethoscope, electrocardiogram (ECG), ultrasound, or necropsy (post-mortem examination). However, even these methods may not be definitive, as we will see in the next part.

 

Part 2: How the Reptilian Heart Keeps Beating After Death

One of the most remarkable features of reptilian hearts is their ability to keep beating after death, even when separated from the body. This phenomenon has been observed in various reptile species, such as turtles, snakes, lizards, and crocodiles. But how is this possible? What makes the reptilian heart so resilient and independent?

The answer lies in the structure and function of the reptilian cardiac tissue. Unlike mammalian hearts, which have a specialized pacemaker region called the sinoatrial node (SA node) that initiates and regulates the heartbeat, reptilian hearts have multiple pacemaker regions distributed throughout the atria and ventricles. These regions are composed of nodal cells, which are modified cardiac muscle cells that can generate spontaneous electrical impulses without any external stimulation. These impulses travel through specialized conducting fibers called nodal tissue, which connect the different pacemaker regions and coordinate their activity.

The main pacemaker region in reptiles is located in the sinus venosus (SV), a thin-walled chamber that receives blood from the body and empties into the right atrium. The SV generates impulses at a regular rate and sends them to the atria and ventricles through the nodal tissue. However, if the SV is damaged or removed, other pacemaker regions can take over and maintain the heartbeat. The most important of these backup pacemakers are located in the atrioventricular node (AV node), which is situated at the junction of the atria and ventricles, and in the ventricular apex (VA), which is located at the tip of the ventricle.

The AV node and VA can generate impulses independently of the SV, but at a slower rate. The AV node also acts as a gatekeeper that regulates the transmission of impulses from the atria to the ventricles, preventing them from contracting too fast or too slow. The VA can also influence the contraction of the ventricle by sending retrograde impulses (backward impulses) to the rest of the cardiac tissue.

The presence of multiple pacemaker regions and conducting fibers in reptilian hearts gives them a high degree of autonomy and adaptability. They can adjust their rate and rhythm according to various factors, such as temperature, oxygen level, hormonal status, and neural input. They can also survive injury or ischemia (lack of blood supply) better than mammalian hearts, because they have more backup systems and alternative pathways for electrical conduction.

This also explains why reptilian hearts can keep beating after death, even when separated from the body. As long as they have enough oxygen and nutrients, they can generate their own impulses and contract without any input from the brain or nervous system. They can also resist decay longer than other organs, because they have a low metabolic rate and a high concentration of ions that prevent bacterial growth.

However, this does not mean that reptilian hearts are immortal or invincible. They still depend on external factors for optimal functioning, such as temperature regulation, hormonal balance, and neural modulation. They also have limits to their endurance and resilience, especially when exposed to extreme conditions or prolonged stress. Therefore, it is important to monitor and evaluate their health and performance using appropriate diagnostic tools and methods.

 

Conclusion:

The reptilian heart exhibits remarkable post-mortem contractility, even when isolated from the body. This phenomenon is attributed to the distinctive structure and function of the reptilian cardiac tissue, which has multiple pacemaker regions and conducting fibers that can generate and coordinate electrical impulses autonomously of the brain or nervous system. The reptilian heart also possesses adaptations that enable it to withstand harsh conditions and exhibit apparent lifelessness, such as hibernation, anoxia tolerance, and decapitation survival. However, these adaptations also pose challenges to the diagnosis of death in reptiles, and necessitate a comprehensive physical examination and diagnostic tools such as stethoscope, electrocardiogram, ultrasound, or necropsy to assess their cardiac status. Reptile cardiology is an emerging field of veterinary medicine that requires further research and application to improve the health and welfare of captive reptiles.

Sources:

 

Kik MJL, Mitchell MA. Reptile Cardiology: A Review of Anatomy and Physiology, Diagnostic Approaches, and Clinical Disease. Seminars in Avian and Exotic Pet Medicine. 2005;14(1):52-60. https://vetmed.illinois.edu/mmitch/pdf/reptilecardiology.pdf

 

Crossley DA II. Reptilian cardiovascular anatomy and physiology: evaluation and monitoring (Proceedings). DVM360. 2009. https://www.dvm360.com/view/reptilian-cardiovascular-anatomy-and-physiology-evaluation-and-monitoring-proceedings

 

Rupprecht C, Kühn C, Witten PE, et al. Reptilian heart development and the molecular basis of cardiac chamber evolution. Nature. 2009;461(7260):95-98. https://www.nature.com/articles/nature08324

 

Johnson A, Clinton J, Stevens R. Turtle heart beats five days after death. Amer Biol Teacher. 1957;19(6):176-177. https://online.ucpress.edu/abt/article/19/6/176/4675/Turtle-Heart-Beats-Five-Days-after-Death

Here are some photos that were taken during a necropsy we did on a turtle with some of our Vet Program students:

 

 

#vetstudentexperience #veterinary #vet #vetmed #vetlife #veterinarian #veterinarymedicine #vettech #vetstudent #vetschool #reptilecardio #reptileanatomy #reptilephysiology #reptilediagnosis #reptiledisease #postmortemheart #reptilecare #reptilelove

The Lion’s Share: How Inbreeding Affects the Conservation and Management of South Africa’s Lions

The Lion’s Share: How Inbreeding Affects the Conservation and Management of South Africa’s Lions

Lions are among the most iconic and charismatic animals in the world. They are admired for their strength, beauty and courage, and they play a vital role in maintaining the balance of ecosystems. However, lions are also facing serious threats from habitat loss, human-wildlife conflict, poaching and disease. In South Africa, where lions are classified as vulnerable, there are various efforts to conserve and manage these majestic predators in both protected areas and private reserves. In this article, we will explore some of the challenges and opportunities for lion conservation and management in South Africa, with a special focus on the issue of inbreeding in lions.

The Perils of Inbreeding: How Genetic Diversity Affects Lion Health and Survival

Inbreeding is the mating of closely related individuals, such as siblings or cousins. Inbreeding can result in reduced genetic diversity, which can have negative consequences for the health and survival of animals. Inbreeding can cause inbreeding depression, which is a decline in fitness due to increased expression of harmful recessive genes or reduced ability to adapt to environmental changes. Inbreeding can also increase the risk of genetic diseases, such as immune disorders, infertility, deformities and cancers.

Inbreeding is a major concern for lion populations that are isolated, fragmented or small. In South Africa, many lion populations are confined to fenced reserves or parks that limit their natural dispersal and gene flow. For example, a lion population of 84 individuals in Hluhluwe-iMfolozi Park displayed severe inbreeding depression and crashed to 20 native individuals and their offspring between 2002 and 20041. A genetic study of lions across Africa revealed that South African lions have lower genetic diversity than other regions, and that some populations have unique haplotypes (groups of genes) that indicate historical isolation2.

In order to prevent or reduce the negative effects of inbreeding, lion managers need to monitor the genetic status of their populations and implement strategies to increase genetic diversity. Some of these strategies include:

Translocating lions between reserves or parks to increase gene flow and create metapopulations (networks of interconnected populations).

Introducing new lions from different sources (such as captive-bred or wild-caught) to increase genetic variation and avoid genetic bottlenecks (drastic reductions in population size).

Managing lion densities and sex ratios to ensure adequate breeding opportunities and avoid competition or aggression.

Implementing best practices for lion hunting (if allowed) to avoid selective removal of genetically valuable individuals or groups.

Conducting genetic testing and screening to identify and avoid mating of related individuals or carriers of genetic diseases.

By applying these strategies, lion managers can help maintain healthy and viable lion populations that can contribute to the conservation of this iconic species.

The Mystery of the White Lions: A Case of Inbreeding or Natural Variation?

One of the most fascinating and controversial phenomena in lion biology is the occurrence of white lions. They have leucism, a rare genetic condition that reduces their pigmentation in fur, eyes and skin. They are mostly found in the Timbavati region in South Africa, where they are sacred to the locals.

Their origin and significance are debated. Some researchers believe that they are from inbreeding among isolated lions, and that they have lower fitness and survival because of their color and disease risk. Others argue that they are a natural variation that has been around for a long time, and that they have no negative effects on their health or reproduction. Some propose that they have an advantage in some habitats or seasons, like during droughts or moonlit nights.

The scientific evidence for these hypotheses is limited and inconclusive. A genetic study of white lions from captive and wild sources showed that they have a unique mutation in a gene called SLC45A2, which affects melanin production. This mutation is recessive, so both parents need to have it for their cubs to be white. The study also showed that white lions are not more inbred than normal lions, and that they have similar genetic diversity. But the sample size was small and did not include any wild white lions from Timbavati.

The conservation status and management of white lions are also contentious. White lions are not recognized as a separate group by the IUCN, and therefore have no legal protection.

Most white lions today are in captivity, where they are bred for money or tourism. Some conservationists want to reintroduce them into their natural habitat, while others disagree as unnatural and risky. The effect of white lions on normal lions is unknown.

White lions are a mystery and a challenge for lion conservation and management. More research is needed to understand their genetic origin, history, role and needs. White lions also raise ethical and cultural questions about the value and purpose of wildlife conservation, and the respect and responsibility we have for these animals.

Some interesting facts about white lions are:

· They have leucism, not albinism, that reduces pigmentation.

· They are sacred to the Timbavati locals in South Africa.

· They have a unique mutation in SLC45A2 that causes their white color.

· They are not more inbred than normal lions, but have less genetic diversity than other regions.

· They are not legally protected by the IUCN, and most are in captivity.

The Trouble with Walking: How Inbreeding Affects Lion Mobility and Coordination

One of the most visible and disturbing signs of inbreeding in lions is the impairment of their mobility and coordination. They struggle to walk, run, jump and hunt. They may be lame, stiff, shaky, weak or paralyzed. Their posture, gait or balance may be abnormal. These symptoms affect their well-being, survival and reproduction.

The condition is caused by a genetic disorder called degenerative myelopathy (DM), which damages the spinal cord and nerves of the hind limbs. DM is due to a mutation in a gene called SOD1, which protects cells from oxidative stress. The mutation causes toxic substances to accumulate and harm the nerve cells. DM is inherited in a recessive way, so both parents need to have the mutation for their cubs to be affected.

DM is more common and severe in South Africa than in other regions. A study of 102 lions from 19 reserves found that 23% had signs of DM, and 80% had the SOD1 mutation. Lions with DM had worse body condition, reproductive success and survival than normal lions. The study said that DM is a major threat to lion conservation in South Africa, and that it is likely due to inbreeding and genetic drift in small and isolated populations.

The management of lions with DM is difficult and controversial. There is no cure or treatment for DM, and the disease worsens and cannot be reversed. Some lion managers have euthanized lions with DM to end their pain and protect their genetic health. Others have kept them alive and given them supportive care. Some have also bred them with normal lions to lower the mutation frequency.

The prevention of DM in lions requires a comprehensive and proactive approach that involves genetic testing, monitoring, breeding and translocation. Lion managers need to avoid mating carriers of the SOD1 mutation, and increase the genetic diversity and gene flow of their populations. They also need to collaborate and coordinate with each other to share information and resources, and to follow best practices for lion conservation and management.

Lions face many challenges in South Africa and beyond, but they are resilient and adaptable animals that can overcome adversity with our help. By understanding and addressing inbreeding in lions, we can help these magnificent animals thrive in their natural habitats for generations to come.

Some interesting facts about lions with DM are:

· They have difficulty walking, running, jumping and hunting due to nerve damage in their hind limbs.

· They have a mutation in a gene called SOD1 that causes their condition.

· They are more common and severe in South Africa than other regions.

· They have lower fitness, survival and reproduction than normal lions.

· They can be managed by euthanasia, supportive care or breeding with normal lions.

Conclusion

Lions are an important and charismatic species that deserve our attention and protection. In South Africa, inbreeding affects lion health and survival. Inbreeding can cause low genetic diversity, inbreeding depression and genetic diseases. These conditions can harm the appearance, behavior, fitness and reproduction of lions, and threaten their viability. To prevent or reduce inbreeding, lion managers need to monitor the genetic status of their populations and increase genetic diversity and gene flow. They also need to collaborate and coordinate with each other and with other stakeholders to share information and resources, and to follow best practices for lion conservation and management. By doing so, we can help lions roam the wilds of South Africa and beyond for generations to come.

Sources:

Lion Conservation Management | Lions - Convention on the Conservation of Migratory Species of Wild Animals. (n.d.). https://www.cms.int/lions/en/conservation/lion-conservation-management

LiMF – Lion Management Forum of South Africa. (n.d.). https://limf.co.za/

Inbreeding in Lions | ALERT. (2020, January 14). https://lionalert.org/inbreeding-in-lions/

Genetics of the African Lion - Interbreeding among lions | ALERT. (2020, January 8). https://lionalert.org/lion-genetics/

Lane, E. P., Brettschneider, H., Caldwell, P., Oosthuizen, A., Dalton, D. L., Du Plessis, L., … & Kotze, A. (2014). Degenerative myelopathy in captive lions (Panthera leo): case report and literature review. Journal of the South African Veterinary Association, 85(1), 01-07.

 

#vetstudentexperience #veterinary #vet #vetstudent #veterinarymedicine #veterinaria #veterinarian #vetlife #vetmed #medvet #medicinaveterinaria #veterinario

What happens if you don't treat an open wound on a zebra or other wildlife?

What happens if you don't treat an open wound on a zebra or other wildlife?

When a zebra or other wildlife sustains an open wound, it's crucial to treat it promptly to prevent infection and promote healing. Failure to treat an open wound can result in serious consequences that can ultimately threaten the animal's life.

Firstly, an open wound can provide a gateway for bacteria, viruses, and parasites to enter the animal's body, causing infections that can spread rapidly throughout the animal's system. Infections can lead to sepsis, which can be fatal if not treated promptly. Additionally, an infection can lead to systemic inflammation, which can cause organ failure and death.

Secondly, an open wound can also impair an animal's ability to move and perform essential functions such as grazing and drinking water. In cases where the wound is located on the animal's limbs, it can cause limping, which can affect the animal's mobility. If the wound is located on the animal's head or face, it can cause problems with feeding and drinking, leading to malnutrition and dehydration.

Lastly, an untreated open wound can attract predators and scavengers, which can pose a serious threat to the animal's safety. Predators such as lions, hyenas, and wild dogs are drawn to the smell of blood and can easily spot an injured animal. Additionally, scavengers such as vultures and jackals can quickly take advantage of an injured animal, causing further harm.

In conclusion, the failure to treat an open wound on a zebra or other wildlife can have severe consequences, ranging from infection and impaired mobility to attracting predators and scavengers. If you come across an injured animal, it's essential to contact a wildlife rescue organization or veterinarian immediately for prompt treatment.

Sources:

"Infection Control in Wound Management," NCBI, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2923493/

"Inflammatory Response to Wound Infections," NCBI, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3399383/

"Wildlife First Aid and Emergency Care," Humane Society, https://www.humanesociety.org/resources/wildlife-first-aid-and-emergency-care

"Wildlife Emergency Response," International Fund for Animal Welfare, https://www.ifaw.org/uk/wildlife-emergency-response

"Wildlife Rehabilitation," National Wildlife Rehabilitators Association, https://www.nwrawildlife.org/page/Rehab_FAQs

Follow our Instagram here 

#vetstudentexperience

#wildlifeconservation #injuredwildlife #wildlifeemergency #wildlifehealth #wildliferehabilitation