Many human beings have low thresholds for pain and are quick to "pop a tablet" at the merest hint that any type of ache is on the way. Naturally, many pet owners transfer this intolerance to pain on our animals and are eager to administer medication for perceived pain.
However, we may unintentionally end up harming our pets more than helping them. Although some cases of aspirin toxicity in pets is accidental through improper storage of the medication–(pet finds a plastic bottle full of pills and chews it up or grabs a tablet that has fallen to the floor)–most cases are the result of the owner directly administering the tablets without seeking advice from a veterinarian.
Aspirin, also known as acetylsalicylic acid, is part of a group of medications called non-steroidal anti-inflammatory drugs (NSAIDs), and is often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatory medication. Aspirin is a safe-for-humans, over-the-counter drug that has been used since 1897. Although there are formulations designed specifically for dogs, aspirin toxicity occurs when a dog or cat swallows enough of the drug to cause damaging effects to the body.
Aspirin is metabolised (broken down) primarily by the liver, and some of the resulting substances are later eliminated by the kidneys through urine. Cats are not small dogs and lack certain proteins that are needed for the liver to safely break aspirin down, therefore they are more susceptible to aspirin than are dogs.The effects of aspirin can last for five to six times longer in cats than in dogs. Young animals are more susceptible to the toxic effects than are adult animals. Aspirin may cause birth defects, so it should not be given to pregnant animals. Aspirin also interacts with several other drugs, particularly cortisones, digoxin, some antibiotics, Phenobarbital, and Furosemide (Lasix�).
Signs of aspirin poisoning can occur within a few hours to a few days.
Common symptoms include:
Gastrointestinal effects–loss of appetite, abdominal pain, nausea, vomiting, black stools and lethargy. Aspirin toxicity can lead to ulceration of the stomach or intestine and, in extreme cases, stomach or bowel perforation that causes a severe, life threatening, bacterial infection of the abdomen. Gastric (stomach) and intestinal bleeding may cause bloody vomit and melena (black, tarry stools).
Respiratory difficulties–Aspirin stimulates the brain's respiratory center so some cats will pant excessively, although the cat may also experience extreme mental depression with decreased respirations.
Neurological problems–restlessness, anxiety, depression, lack of co-ordination and (rarely) seizures.
Kidney failure–vomiting, diarrhoea, loss of appetite, lethargy, extreme thirst, and dilute urine. Owners may also notice that the urine is diluted (lighter in colour) when the cat urinates.
Bleeding disorders–Aspirin interferes with platelets, which are responsible for helping the blood to clot. Disruption of platelet function increases the amount of time it takes the blood to clot after being cut. Spontaneous bleeding may also occur, causing pinpoint bruises to appear in the skin and on the gums (petechiae).
A diagnosis of aspirin toxicity is often based on obtaining a history of deliberate administration or accidental ingestion. In addition to performing a thorough physical examination, your veterinarian will likely recommend diagnostic tests–a complete blood count (CBC), a biochemistry profile, a urinalysis, an activated clotting time (ACT).Aspirin toxicity can be fatal, but pets can survive if the condition is quickly recognised, diagnosed and treated. Most cases are preventable however, so keep all medications at home out of the reach of curious paws and mouths, and never administer medications intended for human use to your pets unless instructed to do so by your veterinarian.