Causes and Treatment of Cellulitis in Dogs

1 Causes of Canine Cellulitis

1. A bite or other skin injury bruises the local skin and subcutaneous tissue; once infected, it turns into a purulent inflammation.

2. A break in the skin gets infected or triggers folliculitis, which then develops into cellulitis.

3. Improper local or subcutaneous injection of an irritating drug is the most common clinical cause. Typical mistakes include:

(1) Injecting oil-based drugs such as ivermectin, doramectin, or lincomycin directly under the skin, damaging the local tissue.

(2) Leaking an irritating intravenous drug into the subcutaneous tissue and damaging it.

(3) The dog struggling during injection, causing muscle damage or bleeding that pools under the skin and later becomes infected.

(4) Failing to disinfect the injection site beforehand, leading to staphylococcus or streptococcus infection.

(5) Misusing corticosteroids, which lower immunity and the body’s resistance to infection.

2 Symptoms of Cellulitis

1. Shallow lesions: localized redness, swelling, heat, and pain, with the center most severe; the inflammation spreads quickly and the subcutaneous tissue necroses and erodes.

2. Deep lesions: less obvious surface redness, but marked tenderness in the fascial and intermuscular tissue, often with high fever and shivering.

3. Cellulitis of the jaw or neck can cause laryngeal edema and airway compression, leading to breathing difficulty and even suffocation.

4. Anaerobic cellulitis brings widespread fascial and progressive skin necrosis, foul-smelling pus, and severe systemic signs, often around the groin or on back/abdominal wounds.

3 Treatment Methods

In early cellulitis without pus or effusion, most dogs recover after a few days of oral antibiotics. Severe cases need surgical debridement, which is reliable and causes little tissue damage, but the surgery must follow these principles:

1. Thoroughly remove all dead tissue. Cut out the swollen lesion along its base with nothing left behind, and avoid letting purulent fluid contaminate healthy tissue.

2. Achieve reliable hemostasis. Ligate bleeding points rather than relying on pressure or a hemostat.

3. Close dead space when suturing. For deep wounds, place deeper sutures through the subcutaneous tissue so the skin lies tightly against it, preventing fluid pockets.

4. If the dog has a high fever and systemic signs, delay surgery. First give high-dose antibiotics and metronidazole by IV until the temperature and systemic signs normalize, to avoid shock or death during or after the operation.