Short answer. Yes. If there are reasonable grounds to fear the pledged item will be destroyed or damaged through no fault of the creditor, the owner may take it back by offering another thing in pledge of the same kind and no worse in quality. The creditor, for his part, must warn the owner of any danger without delay.
What the law says
If there are reasonable grounds to fear the destruction or impairment of the thing pledged, without the fault of the pledgee, the pledgor may demand the return of the thing, upon offering another thing in pledge, provided the latter is of the same kind as the former and not of inferior quality
Civil Code, Article 2107 — Substitution on Danger Without Fault. Read the full provision →
What the article allows
Article 2107 gives the owner a way out when the security is decaying: If there are reasonable grounds to fear the destruction or impairment of the thing pledged, without the fault of the pledgee, the pledgor may demand the return of the thing, upon offering another thing in pledge, provided the latter is of the same kind as the former and not of inferior quality. The pledgor is the owner who gave the item as security; the pledgee is the creditor holding it. Note the words without the fault of the pledgee: this provision is about deterioration that nobody caused.
A swap, not a release
The remedy is substitution. You get your item back and the creditor receives another in its place. The debt itself is untouched, and the new item stands as security exactly as the old one did. Two conditions limit the right. The replacement must be of the same kind as the former, and it must not be of inferior quality. Offering something more convenient for you but weaker as security does not satisfy the article. The provision also expressly preserves the creditor's own rights under the article that follows it, so this is not a lever a debtor can use to force a swap the creditor may resist.
The creditor must speak up
The duty runs both ways. The pledgee is bound to advise the pledgor, without delay, of any danger to the thing pledged. A creditor who sees damp reaching stored goods, an animal falling ill, or a machine corroding cannot sit on that information and produce it afterwards. Two innocent people are involved here: neither caused the deterioration, and the article's answer is to give the owner a chance to act while acting is still worth something. A creditor who stays silent and lets the security fall apart weakens his own position as surely as the owner's.
Pawnshops, and practical steps
One caution. Pawnshops are separately regulated, and a pawn transaction is governed by that regulation as well as by these general Civil Code provisions, so the periods, notices and procedures a pawnshop actually follows may not match the general rule described here — ask for its written terms and read them. In any setting, put the request in writing, describe the replacement precisely, and photograph the condition of the item you say is deteriorating. If the creditor refuses without reason, take advice promptly: time limits apply, and security that is falling apart does not wait for anyone.