Bite Injury
Bite injuries in dogs and cats are one of the most common types of traumatic injuries in small animal medicine. These injuries occur when an animal’s teeth penetrate the skin and underlying tissue of another animal. Bite injuries are characterized by their complex nature: while only small puncture wounds may be visible on the skin surface, significant tissue damage can be hidden underneath. The teeth of dogs and cats act like injection needles, transporting bacteria deep into the tissue. In dogs, the combination of crushing and puncturing leads to more extensive tissue damage, while in cats, the needle-like teeth cause deep but narrow wounds. These differences are crucial for assessing and treating bite injuries. Bite injuries are particularly dangerous near joints, in the chest or abdominal area, as well as in the head and neck region, as vital structures can be affected here.
Causes
The causes of bite injuries are diverse and heavily depend on the social context and environment of the animals. In dogs, bite injuries often occur due to dominance fights, territorial disputes, or resource conflicts over food, toys, or attention. The potential bite injuries depend on the overall situation, such as the owner’s authority, whether dogs are leashed, etc. Furthermore, they depend on the number of dogs involved, the size of the biting dog, its aggressiveness, and the bite force of a dog.
The bite force is measured in PSI (pounds per square inch). For large dogs, it ranges between 195 (Malinois) and 740 (Kangal) PSI. For the German Shepherd, for example, a bite force of 220 PSI is reported.
In comparison, a human has a bite force of 120 to 130 PSI.
The aggressiveness, i.e., how long a dog only threatens when provoked and at what point it bites, has been studied by the American Temperament Test Society and is listed on their website https://atts.org. The Bearded Collie showed the highest threshold, while the French Bulldog had the lowest.
However, the threshold in dogs is not only dependent on breed but also to a large extent on individual differences.
In cats, bite injuries predominantly occur during territorial fights, especially among unneutered tomcats. Lack of socialization, fear, or pain can also lead to biting incidents in both species. In multi-pet households, sudden tensions can arise between previously compatible animals, often triggered by illness of one animal or changes in group dynamics. Bite injuries from wildlife such as foxes or martens should not be underestimated, as they can bring additional infection risks.
Symptoms
Bite injuries can be trivial or life-threatening for your pet.
They are characterized by bruising and tearing and often bleed heavily (Fig.).
They are always associated with the introduction of germs, sometimes also hair and other foreign bodies into the wound.
They often reach very deep, without always being noticeable from the outside.
Bites from cats can appear inconspicuous but can also penetrate very deeply. They have a very high risk of infection.
Bruising and tearing of tissue in depth can also be dangerous, even if hardly anything is visible from the outside.
Bites can penetrate the chest, abdominal cavity, joints, bones, or other sensitive structures such as the eyes, sinuses, etc., and lead to purulent inflammations there.
Bite injuries should therefore always be treated by a veterinarian.
First Aid
- Cut the hair around the wound.
- Thoroughly wash superficial wounds with fresh tap water and soap, and remove visible foreign bodies. There are different recommendations for this, but tap water is nearly sterile.
- If you are unsure whether the chest, abdominal cavity, joints, or similar sensitive structures have been injured, do not wash out the wound.
- Cover the wound with a light bandage that is as sterile as possible. Do not tie it too tightly and loosen it after a certain time.
- Do not apply any ointments.
- If possible, consider legal consequences while still on site and register the contact details of the owner of the involved dog if applicable.
Diagnosis
The diagnosis of bite injuries begins with a thorough anamnesis and clinical examination. The veterinarian first inquires about the course of the incident, if it was observed, as well as the time of injury, as this is crucial for the treatment strategy. During the clinical examination, the extent of visible injuries is assessed, with the fur in the wound area needing to be shaved to identify all lesions. Particularly important is the palpation of the surrounding tissue to identify swelling, emphysema, or crepitations. For deep or complex bite injuries, imaging techniques such as X-ray, ultrasound, or in special cases CT or MRI may be necessary to detect foreign bodies, air accumulations, or organ injuries. Laboratory tests such as blood count and inflammatory parameters help assess the systemic condition of the animal. For infected wounds, a bacteriological examination with antibiogram is useful to identify the involved pathogens and initiate targeted antibiotic therapy. The most common pathogens in bite injuries are Pasteurella multocida (especially in cat bites), Staphylococcus spp., Streptococcus spp., and anaerobic bacteria such as Bacteroides and Fusobacterium.
Further veterinary measures
Visit a veterinarian on the same day.
Teeth and saliva are not sterile. There is a high risk of infection.
The veterinarian can assess the type of injury. Sometimes they are relatively trivial injuries where local treatment and antibiotic care along with pain medication are sufficient.
However, a large proportion of bite injuries require surgical treatment under general anesthesia, as bruising can lead to dead tissue in depth or injuries to joints, tendons, and ligaments.
In addition to appropriate care, the veterinarian will also keep tetanus risk in mind.
Also consider that in some countries, rabies is still widespread among animals.
The treatment of bite injuries requires a multi-stage approach that depends on the severity, location, and time of presentation. For fresh bite wounds (less than 6-8 hours old), primary surgical care is the goal. After initiating general anesthesia, thorough wound cleaning with sterile saline solution or diluted antiseptic solution is performed. Debridement, the removal of devitalized tissue, is a crucial step in preventing infections. For deep bite wounds, drains are inserted to remove wound secretions and avoid dead spaces. The decision between primary wound closure or open wound treatment depends on the degree of contamination, the time elapsed since the injury, and the location. Generally, the more contaminated the wound and the more time that has passed since the injury, the more likely delayed primary closure or secondary wound healing is indicated. Antibiotic therapy is almost always necessary for bite injuries and should be broad-spectrum, with good efficacy against gram-positive, gram-negative, and anaerobic bacteria. Commonly used antibiotics include amoxicillin-clavulanic acid, clindamycin in combination with fluoroquinolones, or third-generation cephalosporins. Pain management is achieved using non-steroidal anti-inflammatory drugs (NSAIDs) or opioids for severe pain. For bite injuries that have already abscessed, incision, drainage, and irrigation are required, followed by antibiotic treatment.
Prognosis and aftercare
The prognosis for bite injuries largely depends on the location, extent of tissue damage, timing of treatment, and the animal’s general health condition. With early and adequate care, the prognosis for superficial bite injuries is generally good. Complications occur more frequently with delayed treatment, in immunosuppressed animals, or with injuries in critical areas such as joints, thorax, or abdomen. Aftercare plays a crucial role in the success of healing. Regular wound checks are necessary to detect signs of infection or healing disorders early. The bandage should be changed every 1-3 days depending on the wound condition. Antibiotic therapy is usually continued for 7-14 days, or longer for severe infections. An Elizabethan collar or body suit is often necessary to prevent self-traumatization. The animal’s activity should be restricted during the healing phase to avoid impairing wound healing. During aftercare, attention should also be paid to possible late effects such as scarring, limited mobility, or chronic pain. In some cases, physiotherapeutic measures may be necessary to restore full functionality.
Summary
Bite injuries in dogs and cats are complex traumas that can have serious consequences despite often appearing inconspicuous externally. The peculiarity lies in the combination of mechanical tissue damage and bacterial contamination. Dog bites typically cause crush and tear wounds with more extensive tissue damage, while cat bites create deep but narrow puncture wounds due to their needle-like teeth, posing a particularly high risk of infection. Treatment includes surgical wound care, antibiotic treatment, and adequate pain management. Crucial for treatment success are the timing of care, thorough wound cleaning, and proper debridement. Aftercare with regular wound checks and consistent medication administration is essential for uncomplicated healing. Special attention is required for bite injuries near joints, in the thoracic or abdominal area, as well as in the head and neck region. With early veterinary care and consistent follow-up, most bite injuries can be successfully treated and heal without permanent damage.
Outlook on current research
Research on bite injuries in small animals is continuously evolving. Current studies focus on optimizing antimicrobial therapies in light of increasing antibiotic resistance. Local wound dressings with antimicrobial properties, such as silver or honey-based preparations, are being investigated as alternatives or supplements to systemic antibiotic therapy. In the field of wound healing, regenerative therapy approaches are gaining importance. The application of Platelet-Rich Plasma (PRP) or stem cell therapies shows promising results in treating complicated wounds and could be used for severe bite injuries in the future. New imaging techniques such as high-resolution ultrasound and special MRI sequences improve diagnostics, particularly in assessing soft tissue damage and early detection of infections. Intensive research is also being conducted in behavioral medicine to better understand risk factors for biting incidents and develop preventive measures. The development of standardized protocols for initial care and follow-up treatment of bite injuries is another important research area aimed at improving treatment outcomes.
Frequently asked questions (FAQs)
- Why are cat bites often more dangerous than dog bites, even though they appear smaller?
Cat teeth are needle-like and leave deep but narrow puncture wounds that quickly close at the surface. This traps bacteria deep in the tissue, where they can multiply under low-oxygen conditions. Additionally, cat saliva contains particularly aggressive bacteria such as Pasteurella multocida. - When should I take my pet to the vet after a bite injury?
Every bite injury should be examined by a veterinarian, ideally within the first 6-8 hours. Even small wounds can become infected or be deeper than externally visible. - Can I treat a bite wound myself?
First aid such as careful cleaning with water is sensible but does not replace veterinary treatment. Do not use home remedies or disinfectants without veterinary instruction. - Why are bite wounds often not sutured?
Bite wounds are contaminated wounds with a high risk of infection. Primary closure would trap bacteria and increase the risk of infection. Therefore, they are often left open or treated with drains. - How long does it take for a bite injury to heal?
The healing time varies depending on severity and location, ranging from one to several weeks. Superficial wounds heal faster, while deep or infected wounds take longer. - Why is antibiotic therapy almost always necessary for bite injuries?
Animal saliva contains numerous potentially pathogenic bacteria that penetrate deep into the tissue through the bite. Prophylactic antibiotic administration prevents serious infections. - What complications can occur with bite injuries?
Possible complications include abscess formation, sepsis, osteomyelitis, arthritis, pneumothorax (with chest injuries), peritonitis (with abdominal injuries), and in rare cases, tetanus. - Can my pet live normally with other animals again after a bite injury?
After complete healing, this is usually possible, however, traumatic experiences can lead to behavioral changes. A gradual, controlled reintroduction and, if necessary, behavioral therapy support are recommended.
Literature
- Cray M, Berent LM, Weese JS. Treatment of Bite Wounds in Dogs and Cats. Journal of the American Animal Hospital Association. 2021;57(5):227-236.
- Jha S, Gupta P, Al-Sudani T, et al. Microbiology and antimicrobial susceptibility in dog and cat bite wounds: A systematic review. PLoS ONE. 2023;18(1):e0280577.
- Kagan R, Mickelson M. Bite Wound Infections. Veterinary Clinics of North America: Small Animal Practice. 2022;52(4):927-941.
- Nolff MC, Albert R, Reese S, Meyer-Lindenberg A. Comparison of negative pressure wound therapy and silver-coated foam dressings in open wound treatment in dogs: A prospective controlled clinical trial. Veterinary and Comparative Orthopaedics and Traumatology. 2018;31(4):229-238.
- Pratesi A, Grieco G, Morabito S, et al. Prevalence of methicillin-resistant staphylococci isolated from the oral cavity of dogs and cats and genetic characterization of methicillin-resistant Staphylococcus pseudintermedius strains. Journal of Veterinary Diagnostic Investigation. 2021;33(5):910-917.
