Onrex (Ondansetron)

Ondansetron, the primary active component in the brand Onrex, is used to manage and prevent severe nausea and vomiting in both dogs and cats. It is particularly beneficial for dogs experiencing nausea due to parvovirus, chemotherapy, or vestibular disease, and for cats with chronic kidney disease. This drug may also be recommended before anaesthesia to prevent nausea and vomiting. It's important to note this medication is typically prescribed for cats and dogs on an "off-label" basis, meaning its use in such cases is at the discretion of the veterinarian.

Ondansetron functions by blocking the action of serotonin, a neurotransmitter involved in triggering nausea and vomiting. By inhibiting serotonin release, it effectively reduces these symptoms in pets.

Always follow the dosing instructions provided by your veterinarian or those on the drug label. Ondansetron can be given with or without food, however if vomiting occurs without food, it may be suggested to give with food. Some tablets are dissolvable, so be sure your hands are dry before handling these tablets.

Missed Dose:

If you miss giving a dose to your pet, consult your veterinarian for advice on how to proceed.

Overdose:

Signs of an overdose may include symptoms such as constipation, diarrhea, grogginess, and head shaking. In such cases, immediately contact your veterinarian or the New Zealand National Poisons Centre at www.poisons.co.nz/animal-helpline/ or phone 0800 869 738.

It is crucial to use Ondansetron cautiously, especially in dogs with the MDR1 gene mutation (most commonly Collies and Australian Shepherds), as they may have difficulty metabolising the drug. This medication is also not suitable for pets with a known sensitivity or allergy to it, or those with certain medical conditions like liver disease. Always consult with your vet to ensure that Ondansetron is appropriate for your pet.

Most pets tolerate Ondansetron well, but some may experience side effects like constipation, diarrhea, extrapyramidal signs (like head shaking), arrhythmias, sedation, or hypotension.

Store Ondansetron as per the manufacturer's instructions, typically at controlled temperatures of 2-30°C. Keep it away from moisture and light and out of reach of children and pets.

What dosage of Ondansetron is safe for my dog or cat?

• The appropriate dosage depends on various factors like your pet's health, age, weight, and breed. Always consult your veterinarian for the right dosage.

Is ondansetron used for conditions other than vomiting in pets?

• No, ondansetron is specifically used to manage nausea and vomiting in dogs and cats.

Can I give my pet Ondansetron prescribed for humans?

• No, it's important not to give your pets medication prescribed for humans, as the dosages and formulations can differ. Always use medications prescribed by your veterinarian.

How long does it take for Ondansetron to work?

• This medication will take effect quickly, in about 1 to 2 hours, and improvement in clinical signs should follow.