Cat Bites

 Updated 3/2017-- photos and all links (except to my own posts) removed as many no longer active.

A blog friend was recently bitten by her cat while she was giving said cat a bath. This wouldn't in most of us be much of an issue, but this blog friend is immunosuppressed. This post is for her.

Animal bites are not uncommon occurrences. The ones seen in emergency centers represent only a small percentage of all bite victims. The majority of reported animal bites are dog bites (80-90%). Cat bites make up only approximately 10%. The rest are bites from miscellaneous animals and rodents.

Most animal bites occur on the extremities, but the head and neck region is also often affected. The head and neck region is injured in 6-20% of persons who sustain cat bites. Children are injured more frequently in the head and neck region than adults.

The incidence of infection transmission is quite low. The risk of rabies is probably the best reason for investigating animal bite injuries. Most cat bites are from pets rather than strays, so the rabies vaccination history should be available.

Medical Care

• IF the skin is only contused and not broken, then simply cleanse the skin thoroughly with soap and water. There is no reason to seek further care unless signs of infection (see below) occurs over the next few days.
• IF the skin is penetrated, copious irrigation is warranted, in addition to thorough cleansing. See your medical doctor or go to the emergency department, especially if you are immunosuppressed or your tetanus is not up-to-date or there is more to the injury (lacerations, continued bleeding, etc).
• Basic wound management is the key. Treatment may include debridement, antibiotic therapy, supportive care, and, possibly, primary suturing or hospitalization with operative debridement. Only 1-3% of all bite injuries (dog, cat, etc)require hospitalization for surgical debridement and intravenous antibiotics.
• Tetanus toxoid is administered. The rabies status of the animal will be investigated.
• The force of a domestic cat's bite does not match that of a dog. Its sharp teeth may cause a puncture wound into which bacterial organisms are inoculated. The risk of infection is compounded by the feline habit of paw licking, which may contaminate their claws with oral flora. The risk of infection is higher following a cat bite than a dog bite. Also, cat bites carry the risk of causing catscratch fever with resultant adenopathy. This is usually self-limited except in immunosuppressed patients.
• Signs of infections are typical and include redness(rubor), pain (dolor), heat (calor), and swelling (edema) of the tissues. Purulent discharge from the wound is another good indicator of infection. Signs of infections may appear 24-72 hours following the bite.

Antibiotic Use in Catscratch Disease
Patients with mild-to-moderate catscratch disease should not receive antibiotics.
For patients with extensive symptomatic lymphadenopathy, azithromycin is recommended.
All immunocompromised patients with catscratch disease, however, should be treated with antibiotics.

Bartonella is an intracellular bacterium and has poor response to penicillin derivatives in vivo despite susceptibility in vitro. A single treatment for all Bartonella-related diseases has not been identified, so treatment must be adapted for specific situations.

Bartonella infections are generally treated with macrolides, tetracyclines, aminoglycosides, or chloramphenicol.

Duration of therapy is commonly at least 3 weeks. Patients should be monitored for evidence of response and drug toxicity. Because these infections often fail to respond to therapy or patients experience relapse later, switching to antibiotics from other classes (eg, erythromycin, clarithromycin, azithromycin, trimethoprim and sulfamethoxazole, or ciprofloxacin) may be needed. Gentamicin may also be effective.

For retinitis, a combination of doxycycline and rifampin for 4-6 weeks is recommended.

For bacillary angiomatosis and peliosis hepatis, long courses of erythromycin or doxycycline are recommended for 3 and 4 months, respectively.

In known Bartonella endocarditis, a combination of doxycycline for 6 weeks with gentamicin 3 mg/kg/d IV for 14 days is recommended.

Some patients, usually who are immunocompromised, develop a Jarisch-Herxheimer–like reaction shortly after receiving antibiotic therapy.

You may also wish to check out my previous post on "Preventing Dog Bites".
REFERENCES
Catscratch Disease; eMedicine Article, August 15, 2006; Roseanne Ressner DO, Lynn Horvath MD
Animal Bites; eMedicine Article, August 1, 2006; Suzanne Galli MD, Philip Miller MD
Bartonellosis; eMedicine Article, October 31, 2007; Kassem Hammoud MD, Daniel Hinthorn MD

Cat Scratch Disease: Bartonellosis; Katharine Hillestad, DVM; Drs. Foster & Smith Veterinary Services Department

From Cat Scratch Disease to Endocarditis, the Possible Natural History of Bartonella henselae Infection; BMC Infect Dis 2007; 7:30; Frédérique Gouriet, Hubert Lepidi, Gilbert Habib, Frédéric Collart, and Didier Raoult