Acetylcysteine for Dogs - Uses, Dosage and Administration

Acetylcysteine is the active ingredient in various drugs sold under various trade names. It has two main uses:

• Mucolytic: it is an agent that reduces the viscosity of mucous secretions. It does so by thinning the mucus without increasing its volume and promoting expectoration by activating the ciliated epithelium.
• Paracetamol overdose: paracetamol can be given to dogs in low doses, but it can be toxic and even fatal in high doses. For this reason, alternative analgesics are often used. Due to its common usage in human medicine, it is possible a dog can overdose either by being given too much or by the dog eating medication left unattended. Acetylcysteine can be given to counteract the overdose.

The mucolytic action of acetylcysteine is achieved by depolymerizing mucoprotein complexes and nucleic acids. This decreases the viscosity of the vitreous and purulent components of our dog's sputum through its free sulfhydryl group (-SH), breaking down disulfide bridges and reducing mucus viscosity.

While use as a mucolytic has been common since the 1960's, other use are less studied. Recent research suggests it might have some useful antioxidant and cytoprotective properties^[1]. Acetylcysteine also exerts an antioxidant effect by acting directly on the electrophilic groups of oxidative radicals due to being part of a free sulfhydryl group (-SH).

You can learn more about avoiding paracetamol overdose in your pet with our article asking can you give paracetamol to dogs?

Acetylcysteine is a drug which is considered safe for use in dogs. However, it's use is considered ‘off label’. While it has been FDA approved for use in human medicine, approval has not yet been given for veterinary use. This does not mean it is dangerous, but it does mean it should only be given by a qualified veterinary professional.

It is primarily used as a mucolytic and as an antidote in cases of paracetamol poisoning in dogs. Overdose can be considered a veterinary emergency, so the veterinarian should be contacted before administering acetylcysteine on your own. Doing so could complicate the clinical picture.

We have explained what is acetylcysteine for dogs and explained its action. This can be used for two main types of treatment. The first main use is as a mucolytic. This activity loosens thick mucus and helps to aid in respiration. This is useful in the following health problems in dogs:

• Bronchitis
• Pneumonia
• Rhinitis
• Chronic respiratory infections

The other indication for acetylcysteine in dogs is its use as an antidote in cases of paracetamol poisoning. This is thanks to its antioxidant action and its ability to regenerate glutathione, which protects the liver. The use of this drug helps protect both the liver and red blood cells, neutralizing the effects of the toxin.

Discover more about the types of liver problems in dogs which can be exacerbated by paracetamol overdose.

The dosage of acetylcysteine for dogs depends on the indication. Dosage is not the same when used as a mucolytic as it is when used as an antidote in cases of paracetamol poisoning. In either case, the veterinarian must calculate the acetylcysteine dose for dogs because the amount indicated on the label will be for human use. These products are sold in either oral suspension or intravenous forms, as well as a liquid solution for use in nebulizers.

With this in mind, we look at the guidelines dosages for acetylcysteine for dogs:

• Oral mucolytic use: the dose is 10–15 mg/kg every 8–12 hours orally for a period of 3 to 7 days, depending on the severity of the dog's disease.
• Nebulizer mucolytic use: 10% acetylcysteine solution (diluted at 1:4 to 1:20 with sterile saline) with a duration to be determined by veterinarian.
• Acetaminophen (paracetamol) antidote use: 140 mg/kg orally or IV as an initial dose with 70 mg/kg every 6 hours for 7 treatments.

Since the paracetamol overdose will be considered a veterinary emergency, the administration of acetylcysteine will most likely be carried out in a veterinary clinic. They can control the intravenous dose and provide detailed information for follow-up administration.

See why a nebulizer can be a helpful tool for your dog's first aid kit with our article on home remedies for phlegm in dogs.

Like all medications, acetylcysteine can cause side effects in dogs. This is especially so if not administered under veterinary supervision or if dosed incorrectly. Some of the side effects of acetylcysteine may include:

• Digestive discomfort: when taken orally, clinical signs such as vomiting, diarrhea, hypersalivation, nausea or lethargy may present.
• Low blood pressure: when given intravenously, it can cause hypotension as well as digestive symptoms such as nausea or vomiting.
• Overdose: if a higher dose than recommended is administered, an overdose can cause severe vomiting, metabolic disturbances and dehydration in our dogs.

Additionally, it is important to note that some presentations of acetylcysteine for dogs contain xylitol or sorbitol, compounds that are toxic to dogs. They can cause liver damage, hypoglycemia and even death. This is another reason it is so important to ensure you should only give this medication under veterinary supervision.

The use of acetylcysteine in dogs has several contraindications. Its unrestricted use by small feline caregivers is strictly contraindicated, as there is an increased risk of overdose and misuse of the medication. Other contraindications for acetylcysteine for dogs include the following:

• Dogs with gastrointestinal problems or gastric ulcers.
• Very young, dehydrated or otherwise weakened dogs, due to the increased risk of side effects.
• Neonatal or nursing dogs, except when used as an antidote for paracetamol overdose.
• Do not use formulations containing toxic excipients such as xylitol, sorbitol or aspartame.
• Do not administer in cases of known allergy or hypersensitivity to acetylcysteine or any of the excipients of the medication.

Although acetylcysteine is very effective in treating various health problems in dogs, there are alternatives to this drug. This is especially so when used as a mucolytic. This is not the case for paracetamol overdose, since it is used in most cases. It is the most effective antidote for acetaminophen in paracetamol. When used as liver protectors and antioxidants , the following alternatives can be used:

• Silymarin: to promote liver regeneration.
• Vitamin C: with antioxidant effect.
• SAMe (S-adenosylmethionine): for its combined antioxidant power and its ability to protect the liver.

Alternatives to acetylcysteine for dogs when used as a mucolytic include:

• Bromhexine: which acts as a mucus thinner.
• Ambroxol: a bromhexine derivative with mucolytic and respiratory epithelial regenerating effects.
• Nebulization with saline solution: helps to hydrate the airways and dissolve mucus.

Discover more about the ailments for which acetylcysteine is used with our article on why a dog has a runny nose with green mucus.

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

If you want to read similar articles to Acetylcysteine for Dogs - Uses, Dosage and Administration, we recommend you visit our Medicine category.