By Rania Gollakner, BS, DVM, MPH

What is tetracycline?

Tetracycline (brand names: Achromycin®, Medicycline®, Sumycin®, Tetracyn®) is a tetracycline-type antibiotic used to treat certain bacterial infections and inflammatory skin conditions in dogs (such as lupus). Many bacteria are now resistant however, and its use for bacterial infections is less common.

Its use in cats, dogs, small mammals, horses, or birds to treat bacterial infections or other conditions is ‘off label’ or ‘extra label’. Many drugs are commonly prescribed for off label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions very carefully as their directions may be significantly different from those on the label.

How is tetracycline given?

Tetracycline is given by mouth in the form of a capsule, tablet, or liquid. Give on an empty stomach if possible, preferably 2 hours apart from feeding. If vomiting occurs when dosed on an empty stomach, then give future doses with a small amount of food. Measure liquid forms carefully. Do not give with milk or other dairy products. After administering the capsule or tablet, administer a syringe of water.

This medication should take effect within 1 to 2 hours, and while effects may not be visibly obvious, gradual improvements are usually noticeable after a few days.

What if I miss giving my pet the medication?

If you miss a dose, give it when you remember, but if it is close to the time for the next dose, skip the dose you missed and give it at the next scheduled time, and return to the regular dosing schedule. Never give your pet two doses at once or give extra doses.

Are there any potential side effects?

Side effects may include nausea, vomiting, lack of appetite, and diarrhea. In cats, side effects are more serious and include stomach pain, fever, hair loss, and depression. Serious side effects associated with long-term use include urinary stone formation, thyroid problems, bacterial or fungal overgrowth, blood cell problems, light sensitivity, and liver toxicity.

This short-acting medication should stop working within 24 hours, although effects can be longer in pets with liver or kidney disease.

It is important to never dry pill your pet and use tablets and capsules cautiously. Esophageal injuries can occur (the esophagus is the tube connecting the mouth and stomach) when dry pilling. To help prevent the risk of injury, follow the dose with a syringe of water.

Are there any risk factors for this medication?

Tetracycline  should not be used in pets that are allergic to it or other tetracycline antibiotics. Do not use in pregnant animals, especially in the first half of pregnancy, as it can affect skeletal and teeth development. Use tetracycline cautiously in pets with kidney or liver disease, or in pets that are lactating. Use extreme caution when using tetracycline in young and growing animals as this medication can cause discolored teeth and may delay bone growth and healing.

Are there any drug interactions I should be aware of?

The following medications should be used with caution when given with tetracycline: atovaquone, beta-lactam or aminoglycoside antibiotics, digoxin, divalent or trivalent cations (oral antacids, saline cathartics, or products containing aluminum, calcium, iron, magnesium, zinc, or bismuth), methoxyflurane, neuromuscular blocking agents, sucralfate, or warfarin.

Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking.

Is there any monitoring that needs to be done with this medication?

There is no specific monitoring that needs to be done while your pet is taking this medication. If using long-term or if your pet is susceptible to risk factors, regular kidney, liver, thyroid, and blood tests may be monitored your veterinarian. Your veterinarian may also monitor your pet to be sure that the medication is working. Monitor your pet at home for serious side effects.

How do I store tetracycline?

Tablets and capsules should be stored at room temperature between 59°F and 86°F (15°C and 30°C) and protect from light and moisture.

What should I do in case of emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility.

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