# Hypothermia in Dogs Treatment: Warming Protocol and Emergency Signs ## Key Takeaways - Hypothermia in dogs is defined as a core body temperature below 37.2°C (99°F) and is a medical emergency, often secondary to anesthesia, trauma, or illness. - Treatment involves controlled rewarming, with passive external rewarming for mild cases and active external or core rewarming for moderate to severe cases, prioritizing gradual temperature increase to prevent rewarming shock. - Emergency signs include a core temperature below 36°C (96.8°F), unconsciousness, fixed pupils, absent shivering, slow/absent breathing or pulse, indicating critical need for immediate veterinary transport. - Unsafe home remedies to avoid include rapid surface warming with hot water, direct application of electric heating pads, vigorous skin rubbing, and forced feeding or watering, as these can cause burns, shock, or aspiration. - Peri-anaesthetic hypothermia is highly prevalent due to impaired thermoregulation and peripheral vasodilation; active warming devices like circulating water blankets and forced-air warmers are standard of care to mitigate this risk. - Special populations like puppies and geriatric dogs are more vulnerable due to immature or declining thermoregulatory systems and reduced physiological reserves, requiring tailored warming and supportive care. --- **Direct answer:** Hypothermia in dogs is a medical emergency defined by a core body temperature below 37.2°C (99°F). Treatment requires immediate, controlled rewarming under veterinary supervision, as the method and rate of warming depend on the severity of the temperature drop, the [dog](/knowledge/veterinary-medicine/clinical-methods/dog)'s cardiovascular status, and the underlying cause. Do not attempt rapid surface warming at home for severely hypothermic dogs, as this can cause dangerous vasodilation and shock. **Owner Triage Summary:** If you suspect your dog has hypothermia, move them to a warm environment immediately. Wrap them in warm blankets (not electric heating pads directly on the skin) and check for shivering. If your dog is unconscious, has a temperature below 36°C (96.8°F), is not breathing normally, or has weak pulses, this is a critical emergency. Transport them to a veterinary clinic immediately while maintaining gentle warmth. Do not rub the dog's skin, do not use hot water, and do not force food or water. Hypothermia is often secondary to anaesthesia, surgery, trauma, or underlying illness, so veterinary assessment is always required even if the dog appears to recover. This article provides a definitive, evidence-based review of hypothermia in dogs, covering the warming protocol, emergency signs, and the science behind current veterinary recommendations. It is educational and is not a substitute for veterinary diagnosis or treatment. ## At a Glance: Hypothermia Severity and Initial Response | Severity | Core Temperature | Common Signs | Immediate Owner Action | Veterinary Treatment Goals | | :--- | :--- | :--- | :--- | :--- | | **Mild** | 32.2°C - 37.2°C (90°F - 99°F) | Shivering, lethargy, seeking warmth, cold ears and [paws](/knowledge/veterinary-medicine/clinical-methods/paws). | Move to a warm room, wrap in blankets, offer warm (not hot) fluids if alert. Monitor closely. | Passive and active external rewarming, treat underlying cause, monitor for shivering. | | **Moderate** | 28°C - 32.2°C (82.4°F - 90°F) | Shivering may stop, muscle stiffness, depression, weak pulse, slow heart rate. | Wrap in blankets, avoid any vigorous rubbing, transport to the vet immediately. | Active external and core rewarming, intravenous fluid therapy, cardiovascular support. | | **Severe** | < 28°C (< 82.4°F) | Unconsciousness, fixed pupils, no shivering, very slow or absent breathing and heart rate. | Immediate emergency transport. Perform rescue breathing if needed. Handle extremely gently. | Aggressive core rewarming, critical care, management of arrhythmias and multi-organ failure. | ## Understanding Hypothermia in Dogs: Physiology and Definition Hypothermia occurs when the body loses heat faster than it can produce it, causing the core temperature to fall below the normal range. A dog's normal rectal temperature is approximately 38.3°C to 39.2°C (101°F to 102.5°F). Hypothermia is defined as a core temperature below 37.2°C (99°F). The body's ability to regulate temperature is a complex balance between heat production (primarily through muscle activity like shivering and metabolic processes) and heat loss (through radiation, conduction, convection, and evaporation). Under general anaesthesia, this regulatory mechanism is profoundly impaired. A study on healthy dogs undergoing ovariohysterectomy found that despite using a circulating warm water blanket, the dogs' rectal temperature decreased by 3.8°F on average, highlighting how susceptible anaesthetised patients are to heat loss [1]. This impairment is a primary reason why hypothermia is one of the most common peri-anaesthetic complications in veterinary medicine [2]. The physiological consequences of hypothermia are systemic. As the core temperature drops, the metabolic rate decreases, leading to a reduction in oxygen consumption and carbon dioxide production. However, this is accompanied by a depression of the central nervous system, cardiovascular function, and respiratory drive. In severe cases, this can lead to bradycardia, hypotension, and a predisposition to cardiac arrhythmias. The body's ability to clot blood is also impaired, increasing the risk of haemorrhage. ## Causes and Differentials: Why Dogs Become Hypothermic Hypothermia in dogs is rarely a primary disease; it is almost always a secondary complication of another condition or event. Understanding the underlying cause is critical for effective treatment. ### Anaesthesia and Surgery This is the most common cause of hypothermia in a clinical setting. General anaesthesia disrupts the thermoregulatory centre in the hypothalamus and causes peripheral vasodilation, leading to rapid heat loss. The study by de Celis Perez et al. (2026) identified hypothermia as the most prevalent peri-anaesthetic complication in dogs undergoing thoracic surgery, occurring in 72 of 90 cases [2]. Similarly, a study on dogs undergoing tibial plateau levelling osteotomy (TPLO) found that all 17 dogs in the study developed intra-operative hypothermia [3]. This is not limited to complex surgeries; it is a risk in any procedure requiring anaesthesia, including diagnostic imaging like MRI [4][5]. ### Environmental Exposure and Exertional Hyperthermia Management While often associated with cold weather, hypothermia can also occur from prolonged exposure to cold water or wind. Interestingly, the management of the opposite condition, hyperthermia, can also lead to hypothermia if cooling methods are too aggressive. A study on post-exercise management of hyperthermia in canicross dogs noted that no dogs developed hypothermia from the cooling methods used (cold-water immersion or cooling coats), but it remains a theoretical risk if active cooling is continued for too long [6]. ### Trauma and Shock Dogs that have suffered significant trauma, such as being hit by a car, are at high risk for hypothermia. Shock, blood loss, and the inability to move or seek warmth all contribute to a drop in core temperature. A retrospective study on traumatic pneumomediastinum found that hypothermia was a common presenting sign in cats, and it is also a concern in dogs with severe trauma [7]. ### Underlying Illness and Sepsis Severe systemic illness can disrupt thermoregulation. For example, dogs with pyometra and sepsis can experience a reduction in rectal temperature, particularly after surgical intervention [8]. Endocrine disorders, such as hypoadrenocorticism (Addison's disease), can also impair the body's ability to respond to stress and maintain temperature. A case report on postoperative nontraumatic adrenal haemorrhage described a dog that developed abrupt decompensation characterised by hypothermia, hypotension, and hypoglycaemia, highlighting how internal medical crises can manifest as hypothermia [9]. ### Pharmacological Effects Certain medications can induce hypothermia as a side effect. Opioids, commonly used for pain management, are known to cause a moderate drop in body temperature. A study investigating the correlation between opioid antinociception and hypothermia found that both butorphanol and methadone significantly decreased rectal temperature in healthy dogs for several hours after administration [10]. Similarly, cannabis oils containing tetrahydrocannabinol (THC) have been shown to cause significant hypothermia in dogs, starting at a dose of 2 mg/kg [11]. This is an important consideration for emergency veterinarians when a dog presents with hypothermia and a history of possible toxin exposure. ## Risk Factors for Hypothermia Several factors can increase a dog's risk of developing hypothermia: - **Breed and Body Condition:** Small and toy breeds have a higher surface-area-to-volume ratio, causing them to lose heat faster than larger breeds. Dogs with low body fat also have less insulation. - **Age:** Puppies and geriatric dogs have less efficient thermoregulatory systems. - **Health Status:** Dogs with underlying heart disease, endocrine disorders, or neurological conditions are more vulnerable. - **Peri-anaesthetic Period:** All dogs under general anaesthesia are at risk, regardless of age or health [1][3]. - **Concurrent Medication:** As noted, opioids and certain other drugs can impair thermoregulation [10]. ## Veterinary Examination and Diagnostics When a dog presents with suspected hypothermia, the veterinarian will perform a thorough physical examination, with a focus on the following: - **Accurate Temperature Measurement:** A rectal thermometer is the standard for measuring core body temperature. This is repeated frequently to monitor the response to treatment. - **Cardiovascular Assessment:** Heart rate, pulse quality, and blood pressure are assessed. Hypothermia causes bradycardia (slow heart rate) and can lead to hypotension (low blood pressure) [4]. - **Respiratory Assessment:** Respiratory rate and effort are evaluated. Severe hypothermia causes a decrease in respiratory rate. - **Neurological Assessment:** The dog's level of consciousness, pupillary light reflexes, and presence of shivering are noted. Shivering is lost in severe hypothermia. - **Diagnostic Testing:** Blood work (complete blood count and biochemistry profile) is often recommended to evaluate organ function, blood glucose levels, and electrolyte balance. It can also help identify underlying causes such as sepsis or endocrine disease. Urinalysis may also be performed. ## Evidence-Based Management: The Warming Protocol The treatment for hypothermia is rewarming. The protocol chosen depends on the severity of the hypothermia and the dog's overall condition. The core principle is to rewarm the body safely and gradually to prevent complications such as "rewarming shock," where cold, constricted peripheral blood vessels suddenly dilate, causing a dangerous drop in blood pressure. ### 1. Passive External Rewarming This is the first step for all hypothermic dogs and is often the only treatment needed for mild cases. It involves moving the dog to a warm, dry environment and providing insulation to prevent further heat loss. This can include: - Wrapping the dog in warm blankets or towels. - Placing the dog on a heated bed or pad (set to a low temperature and always with a barrier between the heat source and the dog's skin to prevent burns). - Increasing the ambient room temperature. ### 2. Active External Rewarming For moderate hypothermia, active external rewarming is used. This involves applying external heat sources to the dog's skin and fur. Common methods include: - **Forced-air warming blankets:** These are considered highly effective in human and veterinary medicine. - **Circulating warm water blankets:** These are commonly used in surgical settings [1][12]. - **Radiant heat lamps:** These must be used with extreme caution to avoid burns. A pilot study compared the efficacy of an innovative warming device placed on the front paws (AVAcore) with conventional truncal warming methods (circulating water blanket/forced air warmer) and no warming in anaesthetised dogs. The study found that at time points beyond 30 minutes of isoflurane maintenance, the slopes of temperature change differed between all three warming device groups, suggesting that the choice of warming method can influence the rate of rewarming [12]. Interestingly, the study also found that the decrease in rectal temperature was significantly greater with acepromazine premedication compared to dexmedetomidine, indicating that the anaesthetic protocol itself influences temperature regulation [12]. ### 3. Active Core Rewarming This is reserved for severe hypothermia and involves warming the body's core directly. Methods include: - **Intravenous fluid therapy:** Warm fluids are administered intravenously to help warm the body from the inside. - **Peritoneal lavage:** This involves infusing warm, sterile fluid into the abdominal cavity. A study on dogs with seawater-immersed open abdominal injuries used a portable peritoneal lavage device for lavaging and rewarming, demonstrating its feasibility in a critical care setting [13]. - **Enemas:** Warm water enemas can be used to warm the colon, though this is less common. ### 4. The Role of Active Warming in Anaesthesia The most effective approach to hypothermia is prevention, particularly in the peri-anaesthetic period. The use of active warming devices, such as circulating water blankets and forced-air warmers, is considered standard of care for anaesthetised patients [1][12][2]. A study on a veterinary Enhanced Recovery After Surgery (Vet-ERAS) protocol for dogs undergoing emergency laparotomy found that the implementation of the protocol, which included measures to prevent hypothermia, resulted in significantly lower intraoperative complications, including hypothermia, and a significant reduction in 15-day mortality (5% vs. 20.7%) compared to historical controls [14]. This underscores the importance of proactive temperature management in improving patient outcomes. ### 5. Monitoring and Supportive Care Throughout the rewarming process, the dog's temperature, heart rate, blood pressure, and respiratory rate are monitored closely. Electrocardiography (ECG) is used to detect cardiac arrhythmias, which are a common complication of hypothermia and rewarming. Supportive care may include: - **Oxygen therapy** for dogs with respiratory depression. - **Intravenous fluids** to support blood pressure and correct dehydration. - **Medications** to address underlying conditions, such as antibiotics for sepsis or specific treatments for toxin exposure. ## Unsafe Home Remedies and What to Avoid In the rush to warm a hypothermic dog, well-meaning owners may inadvertently cause harm. It is crucial to avoid the following: - **Do not use hot water:** Never immerse a hypothermic dog in hot water. This can cause severe burns and rapid vasodilation, leading to shock. - **Do not use electric heating pads directly on the skin:** These can cause severe burns, especially in a dog with reduced sensation or poor circulation. Always use a barrier, such as a towel, between the heat source and the dog. - **Do not rub the dog's skin:** Massaging or rubbing the skin of a severely hypothermic dog can cause cold, acidotic blood from the periphery to be pushed back to the core, potentially triggering cardiac arrest. - **Do not force food or water:** A hypothermic dog may have a reduced gag reflex and be unable to swallow safely. Forcing food or water can lead to aspiration pneumonia. - **Do not use alcohol:** Rubbing alcohol on the skin is an old wives' tale and is dangerous. It cools the skin as it evaporates and can be absorbed into the bloodstream. ## Prevention of Hypothermia Prevention is always better than treatment. Key strategies include: - **Peri-anaesthetic Management:** Veterinary teams should actively warm all patients under general anaesthesia. This includes using circulating water blankets or forced-air warmers before, during, and after the procedure [1][12]. The use of premedication protocols that have a lesser impact on thermoregulation may also be considered. For example, intranasal dexmedetomidine has been shown to mitigate hypotension and hypothermia in dogs undergoing MRI examinations compared to no premedication [4]. - **Environmental Control:** For dogs outdoors in cold weather, provide adequate shelter that is dry and protected from wind. Limit time outside in extreme conditions. For small, short-haired, or senior dogs, consider a well-fitted dog coat or sweater. - **Post-Exercise Care:** After strenuous exercise in cold weather, dry the dog thoroughly and move them to a warm environment. Similarly, after exercise in hot weather, monitor the cooling process to ensure the dog does not become hypothermic [6]. - **Post-Operative Care:** Dogs are at risk of hypothermia for several hours after anaesthesia. Keep them warm, dry, and in a quiet, warm environment at home. Monitor them closely for shivering or lethargy. ## Prognosis and Expected Outcomes The prognosis for a hypothermic dog depends on the severity of the temperature drop, the duration of hypothermia, the underlying cause, and the promptness of treatment. Mild to moderate hypothermia, when treated appropriately, generally carries a good prognosis. However, severe hypothermia is a life-threatening condition with a guarded prognosis, especially if it is associated with severe trauma or underlying organ failure. The study on the Vet-ERAS protocol demonstrated that proactive management of perioperative complications, including hypothermia, can significantly reduce mortality in critically ill dogs [14]. This highlights that with aggressive and comprehensive care, many dogs can recover successfully. ## Emergency Red Flags: When to Seek Immediate Veterinary Care Do not wait to see if your dog improves. Go to a veterinarian or emergency clinic immediately if you observe any of the following: - **Temperature below 36°C (96.8°F).** - **Lethargy or weakness that is progressive.** - **Stiff muscles or difficulty walking.** - **Shivering that stops (a sign of severe hypothermia).** - **Slow or irregular breathing.** - **Weak or slow pulse.** - **Pale or grey gums.** - **Dilated pupils or unresponsiveness.** - **Collapse or unconsciousness.** ## Limitations and When to Contact a Veterinarian This article provides a comprehensive overview of hypothermia in dogs, but it cannot replace professional veterinary advice. The information presented here is based on current scientific literature and clinical guidelines, but every dog is an individual. Breed, age, weight, and pre-existing health conditions can significantly influence how a dog responds to hypothermia and its treatment. The specific warming protocol, diagnostic tests, and medications used will be tailored to your dog's unique situation by a licensed veterinarian. This article also cannot predict the outcome for a specific dog, as this depends on many complex factors. If you have any concerns about your dog's health, especially in an emergency situation, always contact your veterinarian or a local emergency veterinary clinic immediately. ## The Clinical Reality of Rewarming Shock: Why Method Matters The most dangerous moment in hypothermia treatment is not the initial presentation but the rewarming phase itself. When a dog is hypothermic, the body mounts a protective response by constricting peripheral blood vessels, effectively shunting blood away from the skin and extremities to preserve warmth for the vital organs: the heart, brain, and lungs. This cold, acidotic, and relatively oxygen-depleted blood remains sequestered in the periphery. If external heat is applied too aggressively, those vessels suddenly dilate, and that cold, acidic blood is released back into the central circulation. The result can be a precipitous drop in blood pressure, known as rewarming shock, alongside a sudden cooling of the heart that can trigger life-threatening arrhythmias. This is why the warming protocol in veterinary medicine is not simply about applying heat. It is about controlling the rate and route of rewarming to match the dog's cardiovascular capacity. For a mildly hypothermic dog with stable vital signs, passive external rewarming is sufficient because the body's own thermoregulatory mechanisms are still functioning. For a severely hypothermic dog with a core temperature below 28°C (82.4°F), the heart is irritable and the blood vessels are maximally constricted. Rapid surface warming in this state is analogous to pouring warm water over a frozen glass: the thermal shock can be catastrophic. The veterinary team must instead prioritise core rewarming methods that raise the temperature of the heart and great vessels first, while carefully monitoring for arrhythmias and hypotension throughout the process. The evidence base for rewarming strategies in veterinary medicine is still evolving, and much of what is practiced is extrapolated from human medicine. A pilot study comparing an innovative paw-warming device to conventional truncal warming in anaesthetised dogs found that the rate of temperature change differed significantly between warming methods after 30 minutes of anaesthesia, suggesting that the choice of device can meaningfully influence rewarming dynamics [12]. This finding underscores a critical clinical point: there is no single universally superior warming method. The veterinary team must select a strategy based on the dog's temperature, cardiovascular stability, and the resources available, and then adjust that strategy based on continuous monitoring. ## The Diagnostic Workup: Beyond the Thermometer Hypothermia is a clinical sign, not a diagnosis. When a dog presents with a low core temperature, the veterinarian's first priority is to stabilise the patient, but the second priority is to determine why the dog became hypothermic in the first place. This diagnostic workup is essential because treating the hypothermia without addressing the underlying cause can lead to a recurrence or a failure to improve. The initial assessment begins with a comprehensive physical examination. The veterinarian will evaluate the dog's mucous membrane colour, capillary refill time, heart rate, pulse quality, and respiratory effort. These parameters provide immediate clues about the dog's perfusion status. A dog with pale gums, a slow capillary refill time, and a weak femoral pulse is likely in shock, which may be the cause or the consequence of the hypothermia. The neurological examination is equally important. Shivering is a key indicator of the body's attempt to generate heat, and its absence in a hypothermic dog is a poor prognostic sign, as it suggests the metabolic drive has been lost. Diagnostic testing is typically recommended for any dog with moderate to severe hypothermia. A complete blood count can reveal evidence of infection, such as a left shift or toxic neutrophils, which may point to sepsis as the underlying trigger. A biochemistry profile evaluates organ function, particularly the kidneys and liver, which can be compromised by prolonged hypoperfusion. Blood glucose is a critical measurement, as hypoglycaemia can both cause and result from hypothermia. Electrolyte imbalances, particularly hyperkalaemia, can develop in severe cases and predispose the heart to arrhythmias. A urinalysis can assess kidney function and hydration status. In cases where toxin exposure is suspected, such as the ingestion of cannabis oils, additional toxicological screening may be warranted. A study on cannabis oil ingestion in dogs found that hypothermia was a dose-dependent effect, beginning at 2 mg/kg of THC, which highlights the importance of a thorough history in the diagnostic workup [11]. ## The Role of Anaesthesia in Hypothermia: A Preventable Crisis The peri-anaesthetic period is the single most common setting for hypothermia in dogs, and it is also the most preventable. Understanding why anaesthesia causes hypothermia is essential for both veterinary professionals and owners. Anaesthetic agents disrupt the hypothalamic thermoregulatory centre, the brain's internal thermostat. They also cause peripheral vasodilation, which increases heat loss from the skin surface. The combination of a disabled thermostat and increased heat loss means that an anaesthetised dog is essentially poikilothermic, meaning its body temperature becomes dependent on the ambient environment. The magnitude of this problem is substantial. A study on healthy dogs undergoing ovariohysterectomy found that despite the use of a circulating warm water blanket, the dogs' rectal temperature still decreased by an average of 3.8°F [1]. This finding is striking because it demonstrates that even with active warming measures in place, significant heat loss can occur. The study by de Celis Perez et al. (2026) identified hypothermia as the most prevalent peri-anaesthetic complication in dogs undergoing thoracic surgery, occurring in 72 of 90 cases [2]. Similarly, a study on dogs undergoing tibial plateau levelling osteotomy found that all 17 dogs developed intra-operative hypothermia [3]. These studies collectively indicate that hypothermia is not an occasional complication of anaesthesia but an expected event unless aggressive preventive measures are implemented. The clinical consequences of peri-anaesthetic hypothermia extend beyond the immediate recovery period. Hypothermia impairs drug metabolism, prolonging recovery from anaesthesia. It impairs platelet function and the coagulation cascade, increasing the risk of surgical bleeding. It depresses the immune response, potentially increasing the risk of surgical site infections. It also increases the metabolic demand for oxygen as the body attempts to rewarm itself through shivering, which can stress the cardiovascular system in dogs with underlying heart disease. A study on a veterinary Enhanced Recovery After Surgery (Vet-ERAS) protocol for dogs undergoing emergency laparotomy found that implementing a standardised protocol that included active warming measures resulted in significantly lower intraoperative complications and a reduction in 15-day mortality from 20.7% to 5% compared to historical controls [14]. This dramatic improvement in outcomes underscores the critical importance of proactive temperature management in the peri-anaesthetic period. ## Special Populations: Puppies, Geriatrics, and Brachycephalic Breeds Hypothermia does not affect all dogs equally. Certain populations are at significantly higher risk and require tailored management strategies. **Puppies** are particularly vulnerable to hypothermia for several reasons. Their surface-area-to-volume ratio is high, meaning they lose heat rapidly relative to their body mass. Their thermoregulatory centre is immature, and their ability to shiver is not fully developed in the neonatal period. They also have limited energy reserves, making it difficult for them to generate heat through metabolic processes. A hypothermic puppy may present with weak suckling, lethargy, and a decreased heart rate. The treatment approach must be gentle and gradual, as puppies are also at risk of hypoglycaemia and dehydration. Warming should be combined with nutritional support and careful fluid therapy. **Geriatric dogs** face different challenges. Ageing is associated with a decline in metabolic rate and a reduced ability to mount a shivering response. Many senior dogs have concurrent health conditions, such as chronic kidney disease, heart disease, or endocrine disorders, which can impair thermoregulation and reduce their physiological reserve. A senior dog with hypothyroidism, for example, may have a baseline lower metabolic rate and be less able to generate heat. The veterinary team must consider these comorbidities when designing a warming protocol, as aggressive rewarming may stress an already compromised cardiovascular system. **Brachycephalic breeds**, such as Bulldogs, Pugs, and French Bulldogs, present a unique challenge in the context of hypothermia. These breeds are predisposed to upper airway obstruction due to their anatomical conformation. When combined with the respiratory depression caused by hypothermia, these dogs are at high risk of respiratory compromise. The veterinary team must pay close attention to airway patency and be prepared to provide oxygen supplementation or even intubation if necessary. Additionally, the stress of handling and rewarming can exacerbate respiratory distress in these breeds, so a calm, controlled approach is essential. ## The Owner's Role: Observation, First Aid, and Transport Owners are often the first to recognise that their dog is hypothermic, and their actions in the initial minutes can significantly influence the outcome. The first step is to recognise the signs. In mild hypothermia, a dog may shiver, seek out warm places, and have cold ears and paws. As hypothermia progresses, the dog may become lethargic, develop muscle stiffness, and stop shivering. In severe cases, the dog may be unconscious, have dilated pupils, and exhibit slow or absent breathing. Once hypothermia is suspected, the owner should move the dog to a warm environment immediately. The dog should be wrapped in warm, dry blankets or towels. It is important to cover the dog's head and neck, as significant heat is lost from these areas. A hot water bottle wrapped in a towel can be placed against the dog's abdomen, but it must never be placed directly against the skin, as this can cause burns. The owner should avoid any vigorous rubbing or massaging of the dog's skin, as this can push cold, acidotic blood from the periphery back to the core and trigger cardiac arrest. Transport to a veterinary clinic should be undertaken as soon as possible, even if the dog appears to be improving. Hypothermia is often secondary to an underlying condition, such as trauma, sepsis, or toxin exposure, and only a veterinarian can diagnose and treat these conditions. During transport, the dog should be kept warm and handled gently. The owner should be prepared to provide a thorough history, including any possible exposure to cold weather, water, toxins, or medications. They should also be prepared to report the dog's temperature if they have a thermometer, as this information can help the veterinary team triage the case. ## Monitoring the Rewarming Process: What to Expect in Hospital Once the dog is in the veterinary hospital, the rewarming process is carefully managed and monitored. The dog's core temperature is measured rectally at regular intervals, typically every 15 to 30 minutes, to track the rate of rewarming. The goal is to rewarm the dog at a controlled rate, generally aiming for an increase of 1°C to 2°C per hour. Rewarming too quickly can cause rewarming shock, while rewarming too slowly can prolong the period of physiological instability. Continuous electrocardiography (ECG) is used to monitor for cardiac arrhythmias. Hypothermia predisposes the heart to arrhythmias, and the rewarming process itself can trigger them. The most common arrhythmias seen in hypothermic dogs include bradycardia, atrial fibrillation, and ventricular arrhythmias. If an arrhythmia is detected, the veterinary team will assess its significance and may administer anti-arrhythmic medications if necessary. Blood pressure is monitored closely, as hypotension is a common complication of both hypothermia and rewarming. Intravenous fluid therapy is often administered to support blood pressure and correct dehydration. The fluids may be warmed to help with the rewarming process. Blood glucose levels are also monitored, as hypoglycaemia can develop or worsen during rewarming. In severe cases, blood gas analysis may be performed to assess acid-base status and oxygen levels. The duration of hospitalisation depends on the severity of the hypothermia and the underlying cause. A dog with mild hypothermia that responds quickly to passive rewarming may be discharged within a few hours. A dog with severe hypothermia and multi-organ dysfunction may require days of intensive care. Throughout the hospitalisation, the veterinary team will continue to assess the dog's overall condition and adjust the treatment plan as needed. ## The Evidence Base: What We Know and What We Do Not The management of hypothermia in dogs is based on a combination of clinical experience, extrapolation from human medicine, and a growing body of veterinary-specific research. It is important for owners to understand the strengths and limitations of the evidence base, as this informs the recommendations made by their veterinarian. The evidence for the effectiveness of active warming devices in the peri-anaesthetic period is relatively strong. Multiple studies have demonstrated that circulating water blankets and forced-air warmers can reduce the degree of hypothermia in anaesthetised dogs [1][12]. The study on the Vet-ERAS protocol provides compelling evidence that a comprehensive approach to perioperative care, including active warming, can significantly improve outcomes in critically ill dogs [14]. However, the evidence for specific rewarming strategies in severely hypothermic dogs is less robust. There are no large, randomised controlled trials comparing different rewarming methods in dogs with severe hypothermia. Much of the guidance is based on small case series, expert opinion, and extrapolation from human medicine. For example, the use of peritoneal lavage for core rewarming is supported by a study on dogs with seawater-immersed open abdominal injuries, but this is a specific scenario and the findings may not be generalisable to all cases of severe hypothermia [13]. The evidence for the physiological effects of hypothermia is also evolving. Studies have shown that opioids such as butorphanol and methadone can cause significant decreases in rectal temperature in healthy dogs [10]. This finding has important implications for pain management in hypothermic patients, as the administration of opioids may exacerbate the temperature drop. Similarly, the finding that intranasal dexmedetomidine mitigates hypotension and hypothermia in dogs undergoing MRI provides valuable information for anaesthetic protocol selection [4]. Owners should be aware that veterinary medicine is a science as well as an art. The treatment plan for their dog will be based on the best available evidence, but it will also be tailored to the individual dog's circumstances. If a veterinarian recommends a specific warming method or diagnostic test, the owner should feel empowered to ask questions about the rationale and the evidence supporting it. ## Prevention Strategies for Owners and Veterinary Teams Prevention is the most effective strategy for managing hypothermia, and it requires a collaborative effort between owners and veterinary professionals. For owners, prevention begins with environmental management. Dogs that spend time outdoors in cold weather need access to a dry, draught-free shelter that is raised off the ground. The shelter should be large enough for the dog to stand up and turn around but small enough to retain body heat. Dogs with short coats, low body fat, or advanced age may benefit from a well-fitted dog coat or sweater during walks. After any exposure to cold or wet conditions, the dog should be dried thoroughly and moved to a warm environment. Owners should also be aware of the risks associated with strenuous exercise in cold weather. A dog that becomes wet during exercise, whether from rain, snow, or swimming, is at high risk of hypothermia because water conducts heat away from the body much faster than air. After exercise, the dog should be dried and warmed gradually. The management of hyperthermia after exercise in hot weather also requires careful attention, as overly aggressive cooling can lead to hypothermia [6]. For veterinary teams, prevention begins in the pre-anaesthetic period. The dog's temperature should be measured before anaesthesia is induced, and active warming should be initiated before the dog becomes hypothermic. Warming should continue throughout the procedure and into the recovery period. The choice of anaesthetic protocol can also influence the risk of hypothermia. The study comparing acepromazine and dexmedetomidine premedication found that the decrease in rectal temperature was significantly greater with acepromazine, suggesting that the choice of premedication can impact thermoregulation [12]. Similarly, the use of intranasal dexmedetomidine has been shown to mitigate hypotension and hypothermia in dogs undergoing MRI [4]. The implementation of standardised protocols, such as the Vet-ERAS protocol, can help ensure that all members of the veterinary team consistently follow best practices for temperature management [14]. These protocols should include specific guidelines for warming methods, temperature monitoring intervals, and criteria for escalating care. ## Prognosis and Long-Term Outcomes The prognosis for a hypothermic dog depends on several factors, including the severity of the temperature drop, the duration of hypothermia, the underlying cause, and the promptness and quality of treatment. Owners should be prepared for a range of outcomes and should discuss the prognosis with their veterinarian in the context of their dog's specific situation. Mild hypothermia, defined as a core temperature between 32.2°C and 37.2°C (90°F and 99°F), generally carries a good prognosis if treated promptly. These dogs typically respond well to passive external rewarming and supportive care, and they are often discharged within a few hours. The underlying cause of the hypothermia, however, will determine the long-term outlook. A dog that becomes mildly hypothermic due to a brief period of cold exposure may have an excellent prognosis, while a dog that becomes hypothermic due to sepsis will have a prognosis dictated by the severity of the infection. Moderate hypothermia, defined as a core temperature between 28°C and 32.2°C (82.4°F and 90°F), requires more intensive treatment. These dogs may need active external rewarming, intravenous fluid therapy, and cardiovascular support. The prognosis is guarded but generally favourable if the underlying cause is treatable and the dog does not develop complications such as arrhythmias or organ dysfunction. Severe hypothermia, defined as a core temperature below 28°C (82.4°F), is a life-threatening emergency. These dogs are often unconscious, have no shivering response, and may have very slow or absent breathing and heart rate. The prognosis is guarded to poor, even with aggressive treatment. The risk of cardiac arrest, multi-organ failure, and death is significant. However, the study on the Vet-ERAS protocol demonstrated that even critically ill dogs can have improved outcomes with comprehensive, proactive management [14]. This finding provides hope that with aggressive and skilled care, some dogs with severe hypothermia can recover. Long-term outcomes for dogs that survive hypothermia depend on the extent of any organ damage sustained during the hypothermic episode. The brain, kidneys, and liver are particularly vulnerable to hypoperfusion. Some dogs may recover fully, while others may have permanent neurological deficits or chronic organ dysfunction. The veterinary team will monitor the dog closely during the recovery period and may recommend follow-up appointments to assess organ function and overall health. ## The Importance of a Thorough History When a dog presents with hypothermia, the veterinary team will rely heavily on the owner's history to guide the diagnostic workup and treatment plan. Owners should be prepared to provide detailed information about the circumstances leading up to the hypothermic episode. Key questions the veterinarian may ask include: - When did the dog last appear normal? - Was the dog exposed to cold weather, wind, or water? - Has the dog had any recent surgery or anaesthesia? - Is the dog on any medications, including pain medications or supplements? - Could the dog have ingested any toxins, such as cannabis, chocolate, or household chemicals? - Has the dog had any recent trauma, such as being hit by a car or falling? - Does the dog have any known underlying health conditions, such as heart disease, kidney disease, or endocrine disorders? - What has the dog eaten and drunk in the past 24 hours? This information can help the veterinarian distinguish between primary hypothermia, caused by environmental exposure, and secondary hypothermia, caused by an underlying medical condition. The distinction is critical because the treatment approach may differ. A dog with primary hypothermia may only require rewarming and supportive care, while a dog with secondary hypothermia will require treatment for the underlying condition in addition to rewarming. Owners should also be prepared to describe the dog's behaviour and vital signs at the time of presentation. If the owner has a thermometer and was able to measure the dog's temperature, this information is valuable. The owner should also report whether the dog was shivering, whether it was conscious, and whether it was breathing normally. This information can help the veterinary team triage the case and initiate appropriate treatment immediately. ## The Ethical Considerations of Treating Severe Hypothermia The treatment of severe hypothermia raises complex ethical considerations for veterinary professionals and owners. When a dog presents with a core temperature below 28°C (82.4°F) and is unresponsive, the question of whether to initiate treatment, and how aggressive that treatment should be, is not always straightforward. On one hand, there are documented cases of dogs surviving severe hypothermia with aggressive treatment. The study on the Vet-ERAS protocol demonstrated that proactive management of perioperative complications, including hypothermia, can significantly reduce mortality in critically ill dogs [14]. This finding suggests that even severely hypothermic dogs may benefit from aggressive intervention. On the other hand, the treatment of severe hypothermia is resource-intensive and may not be successful. Dogs with severe hypothermia are at high risk of cardiac arrest, multi-organ failure, and death. Even if the dog survives, it may have permanent neurological deficits or chronic organ dysfunction. The cost of intensive care can be substantial, and the emotional toll on the owner can be significant. Veterinary professionals have a responsibility to provide owners with honest, realistic information about the prognosis and the expected outcomes of treatment. They should discuss the risks and benefits of different treatment options and help owners make decisions that align with their values and their dog's best interests. In some cases, the most compassionate approach may be to provide palliative care rather than aggressive intervention. In other cases, the owner may wish to pursue every available treatment option. Owners should feel empowered to ask questions and express their concerns. They should not feel pressured to make a decision quickly, although in an emergency situation, time is of the essence. The veterinary team should provide clear, compassionate communication throughout the process, ensuring that the owner understands the situation and the options available. ## The Intersection of Hypothermia and Other Medical Emergencies Hypothermia rarely occurs in isolation. It is often a component of a broader medical emergency, and the treatment of hypothermia must be integrated with the treatment of the underlying condition. **Trauma:** Dogs that have been hit by a car or suffered other significant trauma are at high risk of hypothermia due to shock, blood loss, and the inability to move or seek warmth. The treatment of hypothermia in a trauma patient must be balanced with the treatment of the injuries themselves. The veterinary team must stabilise the dog's cardiovascular system, control any bleeding, and address any fractures or internal injuries while simultaneously rewarming the dog. **Sepsis:** Severe systemic infection can disrupt thermoregulation and lead to hypothermia. A study on dogs with pyometra and sepsis found that these dogs can experience a reduction in rectal temperature, particularly after surgical intervention [8]. The treatment of hypothermia in a septic dog must include antibiotics, intravenous fluids, and supportive care, in addition to rewarming. **Toxin Exposure:** Certain toxins, such as cannabis, can cause hypothermia as a direct effect. A study on cannabis oil ingestion in dogs found that hypothermia was a dose-dependent effect, beginning at 2 mg/kg of THC [11]. The treatment of hypothermia in a dog with toxin exposure must include decontamination, if appropriate, and supportive care, in addition to rewarming. **Endocrine Emergencies:** Conditions such as hypoadrenocorticism (Addison's disease) can impair the body's ability to respond to stress and maintain temperature. A case report on postoperative nontraumatic adrenal haemorrhage described a dog that developed abrupt decompensation characterised by hypothermia, hypotension, and hypoglycaemia [9]. The treatment of hypothermia in a dog with an endocrine emergency must include hormone replacement therapy and correction of electrolyte and glucose abnormalities, in addition to rewarming. The integration of hypothermia treatment with the treatment of the underlying condition requires a comprehensive, multidisciplinary approach. The veterinary team must continuously assess the dog's overall condition and adjust the treatment plan as new information becomes available. ## Owner Education and Discharge Instructions When a dog is discharged from the veterinary hospital after treatment for hypothermia, the owner will receive detailed discharge instructions. These instructions are critical for ensuring a successful recovery and preventing recurrence. The owner should be instructed to keep the dog in a warm, dry, draught-free environment for at least 24 to 48 hours after discharge. The dog should have access to a comfortable bed with warm blankets. The owner should monitor the dog's temperature regularly, if they have a thermometer, and should be alert for any signs of recurrent hypothermia, such as shivering, lethargy, or cold ears and paws. The owner should also be instructed to monitor the dog's appetite, water intake, and urination. A dog that is recovering from hypothermia may have a reduced appetite initially, but it should gradually return to normal. If the dog refuses to eat or drink for more than 24 hours, the owner should contact the veterinarian. The owner should be alert for any signs of complications, such as difficulty breathing, weakness, collapse, or seizures. These signs may indicate organ dysfunction or neurological damage and require immediate veterinary attention. The owner should also be instructed to follow up with the veterinarian as recommended. The veterinarian may want to recheck the dog's temperature, blood work, or overall condition to ensure that the recovery is progressing as expected. The owner should not hesitate to contact the veterinarian with any questions or concerns during the recovery period. Finally, the owner should be educated about prevention strategies to reduce the risk of future episodes of hypothermia. This includes environmental management, appropriate clothing for cold weather, and careful monitoring during and after anaesthesia. By working together, the owner and the veterinary team can help ensure the dog's long-term health and well-being. ## Frequently Asked Questions **1. What is the fastest way to warm up a hypothermic dog?** The fastest and safest way to warm a hypothermic dog is to use active external warming methods like forced-air warming blankets or circulating warm water blankets, which are typically only available in a veterinary hospital. At home, you can begin by moving the dog to a warm room and wrapping them in warm, dry blankets, but this is passive warming and is slower. **2. Can I use a human heating pad to warm my dog?** Yes, but with extreme caution. Never place a heating pad directly on the dog's skin, as this can cause severe burns. Always place a thick towel or blanket between the heating pad and the dog, and set the pad to the lowest setting. Supervise the dog at all times. **3. How long does it take for a dog to recover from hypothermia?** Recovery time varies greatly depending on the severity of the hypothermia and the underlying cause. Mild cases may recover within a few hours with passive warming. Severe cases may require days of intensive care in a veterinary hospital to stabilise and treat the underlying condition. **4. What temperature is considered hypothermia in dogs?** A core body temperature below 37.2°C (99°F) is considered hypothermic. A temperature below 28°C (82.4°F) is classified as severe hypothermia and is a life-threatening emergency. **5. What are the late signs of hypothermia in dogs?** Late or severe signs of hypothermia include the cessation of shivering, muscle stiffness, a very slow heart rate and breathing, dilated pupils, unresponsiveness, and unconsciousness. These signs indicate a critical medical emergency. **6. Is shivering always a sign of hypothermia in dogs?** Shivering is a primary sign of mild to moderate hypothermia, as it is the body's way of generating heat. However, shivering can also occur due to pain, anxiety, or fever. In severe hypothermia, shivering stops because the body's metabolic processes are too depressed to continue. **7. Why is my dog cold after surgery?** Hypothermia is a very common complication of general anaesthesia. Anaesthetic drugs impair the brain's ability to regulate body temperature and cause blood vessels to dilate, leading to rapid heat loss [1][3]. Veterinary teams use active warming methods during surgery to minimise this, but dogs can remain cool for several hours after the procedure. **8. Can hypothermia in dogs be prevented?** Yes, in many cases. The most critical area is during the peri-anaesthetic period, where active warming is standard practice [14][12]. At home, prevention focuses on providing a warm, dry environment, limiting exposure to cold weather, and drying dogs thoroughly after they get wet. ## Sources [1] [Prospective evaluation of nonporous wrap fails to minimize inadvertent perianesthetic hypothermia in healthy canine patients undergoing ovariohysterectomy.](https://pubmed.ncbi.nlm.nih.gov/40816332/) [2] [Peri-anaesthetic complications in dogs undergoing lateral thoracotomy or median sternotomy: A retrospective study.](https://pubmed.ncbi.nlm.nih.gov/41565489/) [3] [Two doses of subcutaneous methadone for postoperative analgesia in dogs undergoing tibial plateau levelling osteotomies.](https://pubmed.ncbi.nlm.nih.gov/38594836/) [4] [Intranasal dexmedetomidine as premedication for magnetic resonance imaging examinations in dogs with neurological disorders mitigates hypotension and hypothermia.](https://pubmed.ncbi.nlm.nih.gov/37879359/) [5] [Variation of rectal temperature in dogs undergoing 3T-MRI in general anesthesia.](https://pubmed.ncbi.nlm.nih.gov/37559890/) [6] [Post-exercise management of exertional hyperthermia in dogs participating in dog sport (canicross) events in the UK.](https://pubmed.ncbi.nlm.nih.gov/38518416/) [7] [Retrospective evaluation of traumatic pneumomediastinum in dogs and cats (2005-2022): 52 cases.](https://pubmed.ncbi.nlm.nih.gov/38728066/) [8] [Impact of hyperbaric oxygen therapy on tolerability, clinical signs, lactatemia and glycemia in patients with pyometra.](https://pubmed.ncbi.nlm.nih.gov/41223391/) [9] [Presumptive Postoperative Nontraumatic Adrenal Haemorrhage After Orthopaedic Surgery in a Dog.](https://pubmed.ncbi.nlm.nih.gov/42499308/) [10] [Correlation of opioid antinociception and hypothermia in dogs-An animal welfare refinement.](https://pubmed.ncbi.nlm.nih.gov/37930056/) [11] [Cumulative Effects of Cannabis Oils on Body Temperature, Electrocardiography, Heart Rate Variability, Blood Pressure, and Respiratory Function in Telemetered Dogs.](https://pubmed.ncbi.nlm.nih.gov/42131827/) [12] [Comparison of two active warming techniques on body temperature in healthy, anesthetized dogs premedicated with acepromazine or dexmedetomidine: A pilot study.](https://pubmed.ncbi.nlm.nih.gov/39883594/) [13] [Application of Portable Peritoneal Lavage Device to Explore the Effect of Different Lavage Fluid Volumes on Dogs with Seawater-Immersed Open Abdominal Injury.](https://pubmed.ncbi.nlm.nih.gov/35049396/) [14] [Veterinary Enhanced Recovery After Surgery (Vet-ERAS) Program in Dogs Undergoing Emergency Laparotomy.](https://pubmed.ncbi.nlm.nih.gov/40284879/) [15] [Partial Venous Inflow Occlusion under Mild Hypothermia for Membranectomy in a Dog with Cor Triatriatum Dexter.](https://pubmed.ncbi.nlm.nih.gov/37760321/) [16] [Anaesthetic management and peri-operative complications in dogs undergoing cardiac electrophysiology studies and radio-frequency catheter ablations.](https://pubmed.ncbi.nlm.nih.gov/41427126/) [17] [80 Years After the First Blalock-Thomas-Taussig Shunt: Cardiac Research in Canines That Saved Lives.](https://pubmed.ncbi.nlm.nih.gov/40627999/) [18] [Dorsal laminectomy for the treatment of lateralised cervical intervertebral disc extrusions in dogs-Prognosis and complications.](https://pubmed.ncbi.nlm.nih.gov/38711538/) [19] [Simultaneous surgical repair of a cardiac myxoma causing left ventricular outflow tract obstruction and a ventricular septal defect in a small dog.](https://pubmed.ncbi.nlm.nih.gov/38549570/) [20] [Percutaneous transvenous coil embolization of congenital intrahepatic portosystemic shunts in small- and toy-breed dogs: 20 cases (2015-2021).](https://pubmed.ncbi.nlm.nih.gov/35943930/)
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