In most cases, kidney and liver damage is not reversible. Ingestion of large doses of paracetamol can also cause coma or death. Quick treatment is essential for your dog's full recovery without permanent damage to the liver or kidneys.
Signs of toxicity from acetaminophen may develop within 1-4 hours of ingestion. Acetaminophen can cause liver damage or decrease the red blood cell's ability to carry oxygen (methemoglobinemia). Dogs may become depressed or weak, with rapid breathing, a high heart rate, panting, abdominal pain, vomiting or drooling.
If your pet has ingested paracetamol, contact your veterinarian immediately and take your pet to the veterinarian as soon as possible. Do not induce vomiting unless your vet instructs you to.
Untreated paracetamol poisoning may cause varying degrees of liver injury over the 2 to 4 days following ingestion, including fulminant hepatic failure. Rarely, massive overdose may initially present with coma and severe metabolic acidosis.
A mild case of paracetamol poisoning can give your dog an upset stomach, and they may appear to be tired. Other symptoms can include laboured breathing, swelling on the face, neck or limbs, gums turning brownish-grey and jaundice. More serious cases can include signs of staggering, vomiting and restlessness.
Regardless of whether acetaminophen toxicity occurs because of a single overdose or after repeated supratherapeutic ingestion, the progression of acetaminophen poisoning can be described in four sequential phases: preclinical toxic effects (phase one), hepatic injury (phase two), hepatic failure (phase three), and ...
Acute liver failure in acetaminophen poisoning
The most sensitive prognostic marker is prothrombin time (PT).
If the glutathione runs out, then the toxic substances build up and damage liver cells. An adult body can produce enough glutathione to safely clear 4 grams of paracetamol every 24 hours which is why it is the recommended dose. Taking more than this amount risks permanent and even fatal liver damage.
Paracetamol toxicity, albeit accidental or intentional overdose, is an ongoing global problem that continues to result in cases of hepatotoxicity, acute liver failure, and even irreversible liver injury necessitating liver transplantation.
Yet paracetamol can cause serious or fatal adverse effects at around 150 mg/kg for many adults. There is considerable inter-patient variability which depends on age, health and substances taken with the paracetamol. The level is higher for young children.
Paracetamol is a very popular painkiller in humans, however it can be toxic or fatal in small animals. Dogs are less sensitive to paracetamol than cats. A 20kg dog would need to ingest over seven 500mg tablets in order to suffer toxic effects.
"Paracetamol is licensed in dogs as Pardale V for 5 days. The dose in Pardale V works out at 33mg of paracetamol for every kg of body weight, three times daily. The listed dose in most vet formularies is 10mg/kg twice to three times daily," Nick explains.
Should your vet prescribe paracetamol for your dog, it's likely that it will be a dosage of 10mg per kilogram, and should only be given once a day for one or two days.
Depending on the type of poisoning, dogs may take weeks or months to recuperate, and some dogs may have permanent organ damage after recovery.
Many people have no symptoms in stage 1. In stage 2 (after 24 to 72 hours), nausea, vomiting, and abdominal pain may develop. At this stage, blood tests show that the liver is functioning abnormally. In stage 3 (after 3 to 4 days), vomiting becomes worse.
Acetylcysteine has long been recognized as an effective antidote, via oral or intravenous administration, minimizing the risk and severity of acute liver injury if administered sufficiently early after a paracetamol overdose.
Paracetamol has been in use for more than 70 years. The way it works to reduce pain and fever is not fully understood. Paracetamol begins to ease pain and lower a high temperature about 30 minutes after a dose is taken. Its effects usually last for about 4 to 6 hours.
Paracetamol is a common painkiller that is normally safe. If you take more than the recommended amount (an overdose), it can harm the liver and rarely the kidneys.
Acetylcysteine IV (N-acetylcysteine, Parvolex®, NAC) is the treatment of choice. It has near 100% efficacy in preventing paracetamol-induced hepatotoxicity if given within the first 8 hours from ingestion of overdose. It may also be effective up to and possibly beyond 24 hours.
Reversing liver damage Liver Basics
For example, an overdose of acetaminophen (Tylenol) can destroy half of a person's liver cells in less than a week. Barring complications, the liver can repair itself completely and, within a month, the patient will show no signs of damage.
Acute liver failure can happen in as little as 48 hours. It's important to seek medical treatment at the first signs of trouble.
In the third stage (72 hours to 96 hours), liver dysfunction is significant with renal failure, coagulopathies, metabolic acidosis, and encephalopathy. Gastrointestinal (GI) symptoms reappear, and death is most common at this stage.
Prognosis. The mortality rate from paracetamol overdose increases two days after the ingestion, reaches a maximum on day four, and then gradually decreases. Acidosis is the most important single indicator of probable mortality and the need for transplantation.
Abstract. Background: Paracetamol overdose is a frequent cause of fulminant hepatic failure. In fatal cases the most frequent causes of death are cerebral oedema in the early phase or sepsis and multiorgan failure later.
Intravenous acetylcysteine is the antidote to treat paracetamol overdose and is virtually 100% effective in preventing liver damage when given within 8 hours of the overdose.