Boric acid is effective for getting rid of pests like cockroaches and fleas. Even if your cat is sometimes a pest, be careful where boric acid is placed or it could have an unwanted effect on him.
The two most dangerous forms of exposure to boric acid for cats are ingestion and direct skin contact. While cats don't normally eat or lick the boric acid directly, it can stick to their paws and fur. When they clean themselves, they ingest it. If a cat rolls on a carpet or other surface treated with boric acid, he may also get it on his skin.
Compared to many other household chemicals, insecticides and flea control products, boric acid is not very toxic. A healthy adult cat is not likely to become seriously ill unless a very large amount is ingested. Symptoms usually subside as the boric acid leaves the body, and normally there are no long-term effects. Young kittens, elderly cats or cats with chronic illness may suffer more serious effects.
Boric acid can cause vomiting, diarrhea, loss of appetite and weakness in cats. In severe cases, more often seen in young kittens, old cats or ill cats, it can depress the central nervous system, causing seizures or difficulty with coordination. On the skin boric acid can cause an irritation, including redness and swelling. It will also produce extra inflammation and burning anywhere there are wounds or scratches.
There is not much that can be done for a mild case of boric acid ingestion. The most common poisoning treatment, activated charcoal to absorb the poison, is not effective, and vomiting could cause more harm. While it is important to contact a veterinarian for treatment advice if a cat has eaten boric acid, treatment options are limited. In severe cases, a cat may receive dialysis treatments. In cases where boric acid has contacted the skin and caused a reaction, the cat should be bathed as well as possible to remove any residue. A veterinarian may also recommend an ointment to soothe the skin while it heals.