Snake Bite
A snake bite in pets is a potentially life-threatening emergency that requires immediate action. Snake bites occur when venomous snakes insert their fangs into an animal’s skin, injecting toxins. These toxins can have various effects on the body of the affected animal, leading to local and systemic reactions. In Central Europe, the common European adder (Vipera berus) is the most frequent venomous snake responsible for bite injuries in pets. The venom of the adder contains a complex mixture of enzymes and toxins that can cause tissue damage, coagulation disorders, and neurological symptoms. The severity of the poisoning depends significantly on the amount of venom injected, the bite location, the size of the animal, and the time until veterinary treatment.
Causes
There are hardly any venomous snakes in Germany. For bite injuries from snakes abroad, please refer to specialized literature.
The European adder is of significance. It is strictly protected and not aggressive by nature. However, bite injuries can occur when dogs are rummaging.
When bitten by a European adder, a mixture of various active components enters the body of the bitten animal.
The components of the snake venom have anticoagulant effects, increase the permeability of blood vessel walls, damage muscle and nerve cells, and can lead to the breakdown of red blood cells as well as paralysis.
Due to the toxicity of the venom and the amount of venom that enters the body during a bite, animals weighing less than 10 kg are particularly at risk. This affects small dog breeds, young dogs, and cats.
Supplements
In Germany, the European adder (Vipera berus) is the most significant native venomous snake. This protected snake species is not aggressive and usually only bites in self-defense. Snake bites typically occur when dogs or cats encounter European adders while rummaging in underbrush, heathlands, or at forest edges, and either harass or accidentally disturb them. The European adder prefers sunny but sheltered habitats such as forest clearings, moorlands, and heathlands. These animals are particularly active during the spring and summer months.
The venom of the European adder contains a variety of bioactive substances, including hemotoxins that affect blood clotting and cause tissue damage, as well as enzymes that damage cell membranes. These toxins have anticoagulant effects, increase the permeability of blood vessel walls, and can lead to tissue necrosis. They also damage muscle and nerve cells and can cause the breakdown of red blood cells (hemolysis) as well as paralysis symptoms.
Small dog breeds, puppies, and cats weighing less than 10 kg are particularly at risk, as the dose of venom is higher in relation to their body weight. The bite location also influences the severity of the poisoning – bites in the head or neck area are especially dangerous due to their proximity to the brain and the faster systemic spread of the venom.
Symptoms
In snake bite injuries, the legs are usually affected, but snake bites also occur in the facial area of dogs and cats.
The closer the bite is to the brain, the faster and more severe the effect of the toxins.
The individual symptoms can include (Fig.)
- Weakness
- Staggering
- Vomiting
- Diarrhea
- Increased respiratory and heart rate
- Local, very painful edema
- Coagulation disorder
- Destruction of blood cells (hemolysis)
- Paralysis
- Shock
- Coma
The clinical signs of a snake bite can vary depending on the location, amount of venom injected, and the individual reaction of the animal. Typically, symptoms develop within minutes to hours after the bite. At the bite site itself, there is a noticeable, painful swelling that can spread rapidly. Often, two puncture marks from the fangs are visible, surrounded by redness and bruising. The affected body region feels warm and may appear bluish-purple in color as the poisoning progresses.
Systemic symptoms include weakness, staggering, and coordination problems. Many animals show signs of pain and discomfort, such as restlessness, trembling, or whining. In severe poisonings, gastrointestinal symptoms like vomiting and diarrhea may occur. The heart rate increases, breathing becomes faster and shallower, and the mucous membranes may appear pale or cyanotic. Due to the anticoagulant effect of the venom, spontaneous bleeding can occur, for example from the nose, gums, or in the form of blood in the urine.
As the poisoning progresses, neurological symptoms such as paralysis, clouding of consciousness up to coma can occur. In severe cases, hypovolemic or toxic shock with hypotension develops, which can lead to death if left untreated. The symptoms usually peak after 12-24 hours but can last for several days depending on the severity of the poisoning and the initiated therapy.
First Aid
- Clean the bite wound with soap and water and cover the wound. Proceed as you would with any other injury.
- If a limb is bitten, do not tie off the corresponding leg (no tourniquet).
- Do not cut into the wound to flush out the venom. Also, do not try to remove the venom in any other way.
- Do not harm the snake, it is protected by nature conservation laws, and do not try to catch it.
- The need to seek veterinary care immediately exists for cats and small dogs (<10 kg body weight), for bites to the animal's face, and when there is significant swelling and pain symptoms at the bite site.
Diagnosis
The diagnosis of a snake bite is primarily based on the anamnesis and clinical presentation. Crucial is the information about possible contact with a snake or the animal’s presence in a habitat where venomous snakes occur. The characteristic local changes at the bite site, such as swelling, pain, and possibly visible puncture marks from the fangs, strengthen the suspicion.
During the clinical examination, vital parameters (heart rate, respiratory rate, body temperature, mucous membrane color, capillary refill time) are recorded, and neurological function is assessed. The extent of swelling should be documented to monitor the progression.
Various laboratory parameters can provide indications of snake bite envenomation. A complete blood count can show anemia due to hemolysis or blood loss, as well as thrombocytopenia. Coagulation parameters such as prothrombin time (PT) and activated partial thromboplastin time (aPTT) are often prolonged. Blood chemistry may reveal elevated creatine kinase (CK) values as a sign of muscle damage, as well as changes in kidney and liver values.
In severe poisonings, further examinations such as electrocardiogram (ECG), blood gas analysis, and ultrasound examinations of the abdomen and thorax are useful to detect complications early. The differential diagnosis includes other causes of acute swelling and systemic diseases, such as insect stings, bite injuries from other animals, allergic reactions, or acute infections.
Further veterinary measures
The treatment for venom intoxication from an adder is primarily symptomatic, meaning vital functions are ensured and supported.
There is an antiserum available, but its administration can be associated with allergic reactions.
On the other hand, one must consider that an antiserum should be administered as early as possible after a snake bite, as otherwise its effectiveness decreases over time.
Supplements
Treating a snake bite requires quick and systematic action. Initially, stabilizing the patient is the priority. In case of circulatory problems, intravenous fluid therapy is initiated to ensure perfusion of vital organs and promote toxin excretion. Analgesics are administered for pain relief, though non-steroidal anti-inflammatory drugs should be used cautiously due to possible coagulation disorders. Opioids like buprenorphine or methadone are often the first choice.
For pronounced swelling that may impair breathing, especially with bites in the head and neck area, monitoring the airways is essential. In severe cases, oxygen therapy or even temporary intubation may be necessary.
Specific therapy includes administering antivenin (antiserum), if available. In Europe, a polyvalent antivenin is available that is effective against the venom of various European vipers. Administration should occur as early as possible, as effectiveness decreases with time after the bite. Before use, the risk of allergic reactions to the antivenin must be weighed, which is why careful monitoring during administration is necessary.
Depending on the clinical picture, additional medications are used supportively: antihistamines and corticosteroids can reduce inflammatory reactions and swelling. Antibiotic therapy is indicated if signs of bacterial infection are present. In cases of coagulation disorders, administration of vitamin K or, in severe cases, transfusion of fresh plasma or whole blood may be necessary.
Local wound care includes careful cleaning of the bite site and, if necessary, applying a sterile, not too tight bandage. In cases of extensive necrosis, surgical debridement may be required, but this should only be done after the patient has been stabilized and acute poisoning symptoms have subsided.
Prognosis and aftercare
The prognosis after a snake bite depends significantly on various factors: the size of the animal, the amount of venom injected, the location of the bite, and especially the time span until veterinary treatment. Generally, larger animals have better chances of survival than smaller ones, as the dose of venom is lower in relation to body weight. With timely and adequate treatment, the prognosis for most dogs and cats after an adder bite is good to cautiously favorable.
Aftercare plays a crucial role in full recovery. In the first days after the bite, the animal should be kept strictly quiet to minimize the spread of the venom and promote healing. The bite site should be regularly checked for signs of infection or necrosis. Depending on the severity of the poisoning, regular follow-up examinations by the veterinarian are necessary to monitor the healing process.
Laboratory checks to monitor coagulation parameters, blood count, and kidney and liver values should be performed after 24-48 hours and, if necessary, at further intervals. In cases of extensive tissue damage, healing can take several weeks and may leave scarring or functional limitations in some cases.
Long-term complications are rare but can occur, especially in severe poisonings, and include chronic kidney damage, persistent neurological deficits, or impairments in mobility due to scarring. However, complete recovery is expected in most cases if treatment was initiated promptly.
Summary
Snake bites in dogs and cats in Germany mainly represent emergencies caused by the common European adder. The venom of this snake contains complex toxins that can lead to local swelling, tissue damage, and systemic effects such as coagulation disorders and neurological symptoms. Particularly at risk are small animals under 10 kg body weight and bites in the head and neck area.
Clinical signs range from local swelling and pain to systemic symptoms such as weakness, vomiting, respiratory distress, and in severe cases, shock or coma. The diagnosis is based on the medical history, clinical presentation, and laboratory diagnostic tests that can show changes in blood count and coagulation parameters.
Treatment includes stabilizing the patient through fluid therapy, pain management, and if necessary, the administration of antivenom. Supportive measures such as antihistamines, corticosteroids, and antibiotics if needed complement the treatment. With timely and adequate care, the prognosis for most animals is good, with aftercare involving rest and regular check-ups being crucial for complete recovery.
Outlook on current research
Research in the field of snake bite envenomation in pets is continuously evolving. Current studies focus on improving antivenom therapy, particularly on developing species-specific antisera with lower allergenic potential. The fragmentation of antibodies and the production of recombinant antibodies against specific toxin components represent promising approaches.
Another research focus is on the identification and characterization of individual toxin components in the venom of the common European adder and other European vipers. Through a better understanding of the molecular mechanisms of action, targeted antidotes can be developed that specifically neutralize the most harmful components.
There are also advances in supportive therapy. New approaches to preventing and treating tissue necrosis, such as the use of matrix metalloproteinase inhibitors or specific phospholipase A2 blockers, are being investigated. These could reduce local damage after snake bites and accelerate healing.
The development of point-of-care tests for the rapid detection of snake venom in blood or at the bite site could facilitate diagnosis in the future and enable more targeted therapy. Improved protocols for initial care and management of snake bites are also being developed, based on current scientific findings and aimed at further improving the survival chances of affected animals.
Frequently asked questions (FAQs)
- How do I recognize if my pet has been bitten by a venomous snake?
Typical signs include a rapidly increasing, painful swelling at the bite site, often with two puncture marks from the fangs. The animal shows pain, restlessness, and as the poisoning progresses, weakness, staggering, or vomiting. - Are all snake bites in pets dangerous?
Not all snakes are venomous. In Germany, the adder is the main concern. However, bites from non-venomous snakes can also become problematic due to bacterial infections and should be examined by a veterinarian. - What should I do if I suspect my pet has been bitten by a snake?
Remain calm, keep the animal as quiet as possible, and go to the nearest veterinarian immediately. Do not attempt to suck out the poison or cut the wound, and do not apply tourniquets. - How long does it take for symptoms to appear after a snake bite?
Initial symptoms such as swelling and pain usually occur within minutes. Systemic symptoms can develop within 30 minutes to several hours, depending on the amount of venom and the bite location. - Is there an antidote for snake bites in Germany?
Yes, there is a polyvalent antivenom against European viper venom that can be used in severe poisonings. The decision to use it is made by the treating veterinarian based on the clinical presentation. - How can I protect my pet from snake bites?
In known adder areas, dogs should be kept on a leash. Avoid dense undergrowth, piles of stones, and sunny forest edges, especially during warm months when snakes are active. - Can an animal fully recover after a snake bite?
With timely and adequate treatment, full recovery is possible in most cases. However, severe poisonings can lead to long-term complications such as kidney damage or movement restrictions. - Which dog and cat breeds are particularly at risk?
Small breeds under 10 kg body weight are at higher risk due to the higher relative dose of venom. Hunting dogs have an increased exposure risk due to their behavior. For cats, primarily outdoor cats are affected. - How long does recovery take after a snake bite?
The acute phase mostly lasts 24-48 hours. Complete recovery can take several days to several weeks, depending on the severity of the poisoning and potential complications. - Can an animal be bitten by venomous snakes multiple times, and does it develop immunity?
Animals can be bitten multiple times and do not develop natural immunity to snake venom. On the contrary, repeated bites can lead to increased allergic reactions.
Literature
- Löwe, G. and Löwe, O. (2021). Emergencies in Dogs and Cats – A Veterinary Guide. Kynos-Verlag. 208 p.
- Turkovic V, Teichmann S, Dörfelt R. Adder bites in dogs in southern Germany – a retrospective study of 51 cases (2006–2014). Tierärztliche Praxis Kleintiere. 2015;43(4):221-230.
- Lervik JB, Lilliehöök I, Frendin JH. Clinical and biochemical changes in 53 Swedish dogs bitten by the European adder – Vipera berus. Acta Veterinaria Scandinavica. 2010;52(1):26.
- Sutton NM, Bates N, Campbell A. Canine adder bites in the UK: a retrospective study of cases reported to the Veterinary Poisons Information Service. Veterinary Record. 2011;169(23):607.
- Marti E, Sánchez-Valverde MA, Solano-Gallego L. Immune-mediated hemolytic anemia associated with a presumptive snakebite in a dog. Journal of Veterinary Emergency and Critical Care. 2021;31(1):143-147.
- Segev G, Shipov A, Klement E, Harrus S, Kass P, Aroch I. Vipera palaestinae envenomation in 327 dogs: a retrospective cohort study and analysis of risk factors for mortality. Toxicon. 2020;143:114-120.
Swelling of the left side of the face in a Staffordshire Bull Terrier female after being bitten by an adder.