Zeniquin is a popular brand of veterinary antibiotic containing the active ingredient marbofloxacin. Like Baytril, it is a fluoroquinolone with the ability to treat both gram-positive and gram-negative infections by disrupting the replication of bacterial DNA, but it is not a suitable choice for treating infection caused by anaerobic forms of bacteria.

It has a relatively good safety profile and is approved for veterinary use by the FDA.

Recommended Dosage

Note: Marbofloxacin (and any branded form) is available by prescription only and must not be used unless prescribed by a vet. The following dosage information is intended as a rough guide only, always follow the directions of your vet.

The typical dosage of Zeniquin for treating susceptible bacterial infections in dogs is 1.25 – 2.5 mg/lb given once daily. Use of the medicine should be continued for a maximum of 30 days and for at least 48 to 72 hours after clinical symptoms subside when treating skin or soft tissue infections. When treating a urinary tract infection (UTI), administer for at least 10 days and seek a re-evaluation if the condition does not show signs of improving after 5 days.

The medicine should not be given to dogs during the rapid growth phase (first 8 months of life for small/medium breeds, first 12 months for large breeds and first 18 months for giant breeds).

The chart below shows a common dosage of 1.25 mg/lb.
Marbofloxacin dosage for dogs

Dog’s Weight In Pounds: Dosage In Mg:

Administer the medicine on an empty stomach and avoid giving your pet antacids or products containing iron or dairy for 2 hours. Complete the full course of medicine recommended by your vet (unless serious complications make this impossible), stopping treatment as soon as your dog seems to be feeling better can cause the infection to return.

What if I missed a dose?

If you forgot to give a dose, give it as soon as you remember. In cases where you remember within three hours of when the next dose is due, skip the missed dose and continue as per normal. Do not try to make up for the missed dose by giving double the amount as this could lead to overdose and symptoms of toxicity.

Example: A dog weighing 40 pounds may be given 50 mg per day.


Is It Safe?

Zeniquin is considered to have a good safety profile but caution should be practiced (or use of the medicine avoided entirely) when treating a dog who suffers from:

  • Seizures

    Marbofloxacin can stimulate the Central Nervous System in rare cases, which could trigger seizures in susceptible animals.

  • Dehydration

    Dehydration increases the risk of crystalluria (the presence of crystals in urine), a possible side effect of marbofloxacin.

  • Liver/kidney insufficiency

    Following the use of Zeniquin, concentrations of the drug are higher in the liver and kidneys than in the blood, and fluoroquinolones have been known to cause elevated liver enzymes in rare cases.

Aside from this, treatment is not advised for young dogs to avoid cartilage abnormalities. The minimum ages for use are as follows:

Size of Breed

Minimum Age

Small/MediumOver 8 months
LargeOver 12 months
GiantOver 18 months

Pregnancy/Nursing: Avoid the use of marbofloxacin in dogs who are pregnant or nursing.

Safety Guidelines

Follow these guidelines to safely use Zeniquin:

  • Only use under the guidance of a vet
  • Tell the vet about any medical conditions your dog suffers from, particular those which affect the kidneys or liver or which increase the risk of seizures
  • Do not give to a dog during the first 8 – 18 months of his life (depending on breed)
  • Provide plenty of drinking water through the entire duration of treatment

Plenty of water should be provided to avoid dehydration and help to prevent crystalluria.

What Is It Used For?

Marbofloxacin is a broad-spectrum antibiotic which can be used to treat susceptible bacterial infections including:

  • Pasteurella spp.
  • Pseudomonas spp.
  • Salmonella
  • Staphylococcus

It is not able to treat viruses or fungal/yeast infections and is ineffective against anaerobic bacteria.

Side Effects

During treatment with Zeniquin a dog may experience one or more of these side effects:
Most Common

  • Vomiting
  • Diarrhea
  • Loss of appetite
  • Fatigue

Rare (based on other fluoroquinolones)

  • Loss of coordination
  • Crystalluria
  • Seizures
  • Anxiety

Seizures are rare and are only expected to occur in dogs with medical conditions such as epilepsy.


Dogs who receive an overdose of marbofloxacin may experience an increased risk of the side effects listed above plus tremors, red skin and facial swelling. However, in most cases of mild overdose it is unlikely that your dog will experience symptoms other than vomiting and a loss of appetite.


Pfizer (manufacturer)
Plumb’s Veterinary Drug Handbook (sixth edition)