Short answer. Yes. The Civil Code makes the possessor of an animal answerable for the damage it causes without asking whether the animal had bitten before. There is no first-bite allowance and no need to prove the owner was careless. Only two defences are left open to him.
What the law says
The possessor of an animal or whoever may make use of the same is responsible for the damage which it may cause, although it may escape or be lost.
Civil Code, Article 2183 — Liability for Animals. Read the full provision →
What the law says
This responsibility shall cease only in case the damage should come from force majeure or from the fault of the person who has suffered damage.
Civil Code, Article 2183 — Liability for Animals. Read the full provision →
Liability here does not depend on proving negligence
Article 2183 provides that the possessor of an animal or whoever may make use of the same is responsible for the damage which it may cause, although it may escape or be lost. Notice what the sentence does not require. It does not ask whether the owner was careless, whether the gate was faulty, or whether the dog had shown aggression before. The responsibility attaches to keeping the animal, on the reasoning that whoever takes the benefit of having it also takes the risk it creates. The widespread belief that a dog is allowed one bite before its owner is answerable has no basis in this provision.
'Although it may escape or be lost'
That clause forecloses the second answer owners usually give — that the dog got out, so the incident was beyond their control. The article says responsibility survives the escape. Nor is liability confined to the registered owner: it reaches the possessor and whoever makes use of the animal, which can bring in a caretaker, a handler, a relative minding the dog, or a business using it for security. Establishing who actually had the animal at the time is therefore worth doing carefully, because more than one person may answer for the same bite.
The only two exits, and how narrow they are
The article closes the door deliberately: this responsibility shall cease only in case the damage should come from force majeure or from the fault of the person who has suffered damage. Only is the operative word. Force majeure means an event beyond human control, not a lapse in the household routine. The second exit — the fault of the injured person — is the one an owner will reach for by saying the child provoked the dog. How that argument fares depends on the facts and on what can fairly be expected of a child of that age, and it is the point on which these cases are usually contested.
What to do in the first days
Get the child treated and keep every medical record, receipt and photograph of the injury as it heals. Ask the treating doctor about vaccination and follow the advice on observing the animal, because that is a health question before it is a legal one. Note the exact place the bite happened, who saw it, and who had the dog. Report the incident so that an independent record exists rather than only your account. Then take the file to a lawyer, and be wary of accepting a quick payment from a neighbour before the medical picture and any scarring are settled.