Snake bite

Content
Download/Print
Content

Swelling of the left side of the face in a Staffordshire Bull Terrier bitch after being bitten by an adder.

 

Snake bite
A snake bite can trigger severe local pain and swelling as well as systemic signs of poisoning. Depending on the type of venom, blood coagulation disorders, circulatory problems or neurological symptoms are possible. It is considered an emergency because the condition can deteriorate within a short period of time.

A snake bite in pets is a potentially life-threatening emergency that requires immediate action. Snake bites occur when venomous snakes pierce an animal’s skin with their fangs and inject toxins. These toxins can have various effects in the body of the affected animal and lead to local and systemic reactions. In Central Europe, the adder (Vipera berus) is the most common 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 largely on the amount of venom injected, the bite site, the size of the animal and the time until veterinary treatment.

Causes

There are hardly any venomous snakes in Germany. For bite injuries caused by snakes abroad, please refer to specialist literature.
The adder is of significance. It is strictly protected and not aggressive by nature. Nevertheless, dogs may be bitten while rummaging around.
When an adder bites, a mixture of components with different effects enters the body of the bitten animal.
The ingredients of the snake venom have an anticoagulant effect, increase the permeability of the blood vessel walls, damage muscle and nerve cells, and can lead to the breakdown of red blood cells and paralysis.
Animals weighing less than 10 kg are particularly at risk due to the toxicity of the venom and the amount of venom that has entered the body in the event of a bite. This affects small dog breeds, young dogs and cats.

Supplements

In Germany, the adder (Vipera berus) is the most important 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 adders while rummaging in the undergrowth, in heathland or on the edges of forests and harass or accidentally disturb them. The adder prefers sunny but sheltered habitats such as forest clearings, moorland and heathland. The animals are particularly active in the spring and summer months.

The venom of the adder contains a variety of bioactive substances, including hemotoxins that affect blood coagulation and cause tissue damage, as well as enzymes that damage cell membranes. These toxins have an anticoagulant effect, increase the permeability of the 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) and paralysis.

Small dog breeds, puppies and cats with a body weight of less than 10 kg are particularly at risk, as the dose of venom is higher in relation to their body weight. The bite site also influences the severity of the poisoning – bites in the head or neck area are particularly dangerous due to their proximity to the brain and the faster systemic spread of the venom.

Symptoms

Snake bite in dogs and cats

Typical Symptoms:

  • Puncture sites as a sign of the snake’s teeth penetrating
  • Local, very painful swelling
  • Restlessness, lameness (if bitten on the limbs)
  • Nausea, vomiting possible
  • Diarrhea

Alarm signs:

  • Rapidly increasing swelling,
  • Coagulation disorder, tendency to bleed, hematomas
  • Weakness, collapse,
  • Increased respiratory and heart rate, shortness of breath
  • Neurological symptoms (staggering / ataxia, tremors, paralysis),
  • Destruction of blood cells (hemolysis), dark urine
  • Bite in the head/neck area (airway danger)

Escalation/course:

  • 1–6 h: Swelling/coagulation disorder (coagulopathy) can escalate
  • 6–24 h: systemic effects (hypotension, kidneys, shock) possible
  • Later: Necrosis/infection possible at the bite site
  • Coma

 

In the case of bite injuries caused by snakes, the legs are usually affected, but snake bites also occur in the face area in dogs and cats.
The closer the bite is to the brain, the faster and more serious the effect of the toxins.
The individual symptoms can be (see fig.)

The clinical signs of a snake bite can vary depending on the location, amount of venom injected and individual reaction of the animal. Typically, symptoms develop within minutes to hours after the bite. At the bite site itself, there is significant, painful swelling that can spread rapidly. Often, two punctiform puncture sites of the venomous fangs can be seen, surrounded by redness and bruising. The affected area of the body feels warm and can turn bluish-purple as the poisoning progresses.

Systemic symptoms include weakness, staggering / ataxia, and coordination disorders. Many animals show signs of pain and discomfort, such as restlessness, tremors, or whining. In severe cases of poisoning, gastrointestinal symptoms such as vomiting and diarrhea can 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 may 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 and impaired 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 symptomatology usually reaches its peak after 12–24 hours, but can last for several days depending on the severity of the poisoning and the therapy initiated.

First Aid

  1. Clean the bite wound with soap and water and cover the wound. Continue as with any other injury.
  2. If bitten in a limb, do not tie off the corresponding leg (no tourniquet).
  3. Do not cut into the wound to flush out the venom. Also, do not try to remove the venom in any other way.
  4. Do not harm the snake, it is protected by nature conservation, and do not try to catch it.
  5. The need to see a veterinarian immediately exists for cats and small dogs (< 10 kg body mass), for bites on the animal's face, and for significant swelling and pain symptoms at the bite site.

Diagnosis

The diagnosis of a snake bite is primarily based on the medical history and the clinical picture. The decisive factor is information about possible contact with a snake or the animal’s stay in a habitat in which venomous snakes occur. The characteristic local changes at the bite site, such as swelling, tenderness and possibly visible puncture sites of the venomous fangs, reinforce the suspicion.

During the clinical examination, the vital parameters (heart rate, respiratory rate, body temperature, mucous membrane color, capillary refill time) are recorded and the neurological function is assessed. The extent of the swelling should be documented in order to monitor the course.

In terms of laboratory diagnosis, various parameters can provide indications of snake bite poisoning. 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 can show elevated creatine kinase (CK) levels as a sign of muscle damage as well as changes in kidney and liver values.

In severe cases of poisoning, further examinations such as electrocardiogram (electrocardiogram), blood gas analysis and ultrasound examinations of the abdomen and thorax / chest are useful in order to identify complications at an early stage. The differential diagnosis includes other causes of acute swelling and systemic diseases, such as insect bites, bite injuries from other animals, allergic reactions or acute infections.

Further veterinary measures

The therapy for snake venom intoxication caused by an adder is primarily symptomatic, i.e. the vital functions are ensured and supported.
Although there is an antivenom, its administration can be associated with allergic reactions.
On the other hand, it must be borne in mind that an antivenom should be administered as early as possible after a snake bite, as otherwise its effect can be expected to diminish.

Supplements

Treating a snake bite requires a rapid and systematic approach. The initial focus is on stabilizing the patient. In the event of circulatory problems, intravenous fluid therapy is initiated to ensure the perfusion of vital organs and promote the excretion of toxins. Analgesics are administered to relieve pain, although non-steroidal anti-inflammatory drugs should be used with caution due to possible coagulation disorders. Opioids such as buprenorphine or methadone are often the first-line treatment.

In the case of pronounced swelling that can impair breathing, particularly in the case of bites in the head and neck area, monitoring of the airways is essential. In severe cases, oxygen therapy or even temporary intubation may be necessary.

Specific therapy includes the administration of antivenin (antiserum), if available. In Europe, a polyvalent antivenin is available that is effective against the venom of various European vipers. It should be administered as early as possible, as its effectiveness decreases with increasing time after the bite. Before use, the risk of allergic reactions to the antivenin must be weighed up, which is why careful monitoring is required during use.

Depending on the clinical picture, other medications are used to provide support: Antihistamines and corticosteroids can reduce the inflammatory reaction and swelling. If there are signs of a bacterial infection, antibiotic therapy is indicated. In the case of coagulation disorders, the administration of vitamin K or, in severe cases, a transfusion of fresh plasma or whole blood may be necessary.

Local wound care includes careful cleaning of the bite site and, if necessary, the application of a sterile, not too tight bandage. In the case of extensive necrosis, surgical debridement may be necessary, but this should only be carried out after the patient has been stabilized and the acute symptoms of poisoning have subsided.

Prognosis and aftercare

The prognosis after a snake bite depends largely on various factors: the size of the animal, the amount of venom injected, the location of the bite and, above all, the time until veterinary treatment. In general, 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 complete recovery. In the first few days after the bite, the animal should be kept strictly calm in order to minimize the spread of the venom and promote healing. The bite site should be checked regularly for signs of infections or necrosis. Depending on the severity of the poisoning, regular check-ups with the veterinarian are necessary to monitor the healing process.

Laboratory tests to check coagulation parameters, blood count and kidney and liver values should be carried out after 24–48 hours and, if necessary, at further intervals. In the case of extensive tissue damage, healing can take several weeks and in some cases leave scar tissue formation or functional limitations.

Long-term complications are rare, but can occur, particularly in severe cases of poisoning, and include chronic kidney damage, persistent neurological deficits or impaired mobility due to scar tissue formation. However, a full recovery is to be expected in most cases if treatment is initiated in good time.

Summary

Snake bites in dogs and cats in Germany are mainly emergencies caused by the 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. Small animals under 10 kg body weight and bites in the head and neck area are particularly at risk.

The clinical signs range from local swelling and pain to systemic symptoms such as weakness, vomiting, shortness of breath and, in severe cases, shock or coma. The diagnosis is based on the medical history, the clinical picture and laboratory diagnostic tests, which can show changes in the blood count and coagulation parameters.

The therapy includes stabilizing the patient with fluid therapy, pain management, and, if necessary, administering antivenin. 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 a full recovery.

Outlook on current research

Research into snakebite poisoning in pets is constantly evolving. Current studies focus on improving antivenin therapy, particularly on developing species-specific antivenins with lower allergic potential. The fragmentation of antibody and the production of recombinant antibody against specific toxin components are promising approaches.

Another research focus is on identifying and characterizing the individual toxin components in the venom of the adder and other European vipers. A better understanding of the molecular mechanisms of action can lead to the development of targeted antidotes that specifically neutralize the most harmful components.

There is also progress in the field of 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 snakebites and accelerate healing.

The development of point-of-care tests for the rapid detection of snake venom in the blood or at the bite site could facilitate diagnosis in the future and enable more targeted therapy. Similarly, improved protocols for the initial care and management of snakebites are being developed, based on current scientific findings and designed to further improve the survival chances of affected animals.

Frequently asked questions (FAQs)

  1. How do I know if my pet has been bitten by a venomous snake?
    Typical signs are a rapidly increasing, painful swelling at the bite site, often with two punctiform puncture sites of the venomous fangs. The animal shows pain, restlessness and, as the poisoning progresses, weakness, staggering / ataxia or vomiting.
  2. Are all snake bites dangerous for pets?
    Not all snakes are venomous. In Germany, the adder is mainly relevant. However, bites from non-venomous snakes can also become problematic due to bacterial infections and should be examined by a veterinarian.
  3. What should I do if I suspect my pet has been bitten by a snake?
    Stay calm, keep the animal as calm as possible and go to the nearest veterinarian immediately. Do not try to suck out the venom or cut open the wound, and do not apply tourniquets.
  4. How long does it take for symptoms to appear after a snake bite?
    Initial symptoms such as swelling and pain usually appear within minutes. Systemic symptoms can develop within 30 minutes to several hours, depending on the amount of venom and the bite site.
  5. Is there an antidote to snake bites in Germany?
    Yes, there is a polyvalent antivenin against European viper venom, which can be used in severe cases of poisoning. The decision on whether to use it is made by the treating veterinarian based on the clinical picture.
  6. 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 in the warm months when snakes are active.
  7. Can an animal recover completely after a snake bite?
    With timely and adequate treatment, complete recovery is possible in most cases. However, severe poisoning can lead to long-term complications such as kidney damage or restricted movement.
  8. Which dog and cat breeds are particularly at risk?
    Small breeds under 10 kg body weight are more at risk due to the higher relative dose of venom. Hunting dogs have an increased risk of exposure due to their behavior. In cats, mainly free-roaming cats are affected.
  9. How long does it take to recover from a snake bite?
    The acute phase largely lasts 24–48 hours. Complete recovery can take a few days to several weeks, depending on the severity of the poisoning and any complications.
  10. Can an animal be bitten multiple times by venomous snakes 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 lead to increased allergic reactions.

Literature

  • Löwe, G. and Löwe, O. (2021). Emergencies in dogs and cats – A veterinary Guide. Kynos-Verlag. 208 pp.
  • Turkovic V, Teichmann S, Dörfelt R. Adder bites in dogs in southern Germany – a retrospective study of 51 cases (2006–2014). Veterinary Practice Small Animals. 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.