Drug Monograph
Full clinical overview, indications, dosage references & safety notes.
Drug class: Macrolide antibiotic
Main indication: Antibiotic-responsive diarrhea (dogs); cryptosporidiosis
Available forms3 forms · 5 strengths documentedShow all ↓
Oral · tablet
Tablet 50 mg UK veterinary specialTablet 100 mg UK veterinary special
Oral · soluble powder
Soluble powder 100 g bottle tylosin tartrate
2.5 to 2.7 g per level teaspoon.
Injection
50 mg/mL200 mg/mL
No oral solution and no eye drops.
Overview
Tylosin is a time-dependent macrolide antibiotic that binds to the 50S ribosomal subunit, suppressing bacterial protein synthesis.
In small animal medicine, tylosin is used primarily for the treatment of antibiotic-responsive diarrhea in dogs and for cryptosporidiosis. In dogs and cats, administration is predominantly by the oral route.
Indications
Tylosin is used in dogs and cats primarily for gastrointestinal infections caused by susceptible organisms.
In small animal medicine, its main indications are limited and administration is predominantly by the oral route.
- Antibiotic-responsive diarrhea (dogs): It has been used in dogs for antibiotic-responsive diarrhea, and for colitis.
- Cryptosporidiosis: Used in the treatment of cryptosporidiosis.
- Antimicrobial stewardship in diarrhea: Antibiotics are rarely indicated in the treatment of acute or chronic diarrhea, and tylosin is administered after assessing the response to dietary and anthelminthic therapy.
- Pyoderma (dogs): Not a first-line choice, but efficacy has been demonstrated in superficial and deep canine pyoderma, and it may be useful where resistance limits the alternatives.
Dosage (Reference)
Dog
Tylosin is administered predominantly by the oral route in dogs.
The dose depends on the clinical indication, with higher doses recommended for colitis.
| Clinical use | Route | Dose | Frequency | Notes |
|---|---|---|---|---|
| General use | PO | 7–15 mg/kg | Every 12–24 hours | For canine tylosin-responsive diarrhea, studied extra-label regimens include 20–25 mg/kg orally every 24 hours for 7 days. In dogs with a previously documented response, relapse may respond to 5 mg/kg every 24 hours for 7 days. Optimal treatment duration remains uncertain, and recurrence after withdrawal is common. Routine empirical antibiotic treatment of chronic enteropathy is not recommended. |
| Colitis | PO | 12–20 mg/kg | Every 8 hours initially | Administer with food and treat for 14 to 28 days at this interval. The primary reference gives a slightly lower starting dose for this indication, 10 to 15 mg/kg at the same interval. |
| Colitis (maintenance) | PO | 5 mg/kg | Every 24 hours | The maintenance phase of the colitis regimen, begun after the 14 to 28 day induction course. Administer with food. |
| Antibiotic-responsive diarrhea | PO | 20–25 mg/kg | Once daily | This is the dose studied as initial therapy. Lower regimens are also published for the same syndrome at the same interval; the disease texts give 5 to 10 mg/kg, listing tylosin alongside metronidazole and oxytetracycline as alternatives, and a clinical trial found 5 mg/kg sufficient to control relapse. |
| Pyoderma (second-line) | PO | 10–20 mg/kg | Every 12 hours | Continue for 7 days after the active lesion has resolved. Not a first-line choice for pyoderma; considered where resistance limits the alternatives. |
Important dosing notes (dogs):
• Oral administration is the predominant route in dogs.
• For colitis, administer with food and treat for 14 to 28 days. If there is a response, gradually increase the dosing interval through every 12 hours rather than in one step, and reduce the dose as the interval lengthens.
• Dosing a relapse: 5 to 15 mg/kg has been effective in dogs that have relapsed, and 5 mg/kg for seven days controlled diarrhea in a clinical field trial. The interval is unchanged from the table above.
• Giving the powder: Tylosin is usually dispensed as a soluble powder marketed for poultry and pigs, and it is bitter. Small dogs and cats are best given the dose in a capsule; for larger dogs the powder can be measured with a teaspoon and given in food.
• Oral administration is the predominant route in dogs.
• For colitis, administer with food and treat for 14 to 28 days. If there is a response, gradually increase the dosing interval through every 12 hours rather than in one step, and reduce the dose as the interval lengthens.
• Dosing a relapse: 5 to 15 mg/kg has been effective in dogs that have relapsed, and 5 mg/kg for seven days controlled diarrhea in a clinical field trial. The interval is unchanged from the table above.
• Giving the powder: Tylosin is usually dispensed as a soluble powder marketed for poultry and pigs, and it is bitter. Small dogs and cats are best given the dose in a capsule; for larger dogs the powder can be measured with a teaspoon and given in food.
Cat
In cats, tylosin is administered predominantly by the oral route.
| Clinical use | Route | Dose | Frequency | Notes |
|---|---|---|---|---|
| General use | PO | 7–15 mg/kg | Every 12–24 hours | – |
| Cryptosporidiosis | PO | 10–15 mg/kg | Every 12 hours | If a response is seen in the first 7 days and there is no toxicity, continue for 1 week after the diarrhea resolves; some cats need several weeks. A fixed 28-day course is also described. Tylosin can be a gastrointestinal irritant. |
Important dosing notes (cats):
• Oral administration is the predominant route in cats.
• Extra-label use: No tylosin product is labeled for dogs or cats, so every use on this page is outside the label; and for cryptosporidiosis no drug is labeled for animal use in the United States at all.
• Oral administration is the predominant route in cats.
• Extra-label use: No tylosin product is labeled for dogs or cats, so every use on this page is outside the label; and for cryptosporidiosis no drug is labeled for animal use in the United States at all.
Warnings & Precautions
Tylosin should be used cautiously in dogs and cats, particularly in animals with a history of macrolide hypersensitivity or during pregnancy and lactation, as safety has not been fully established.
- Hypersensitivity: Contraindicated in patients with known hypersensitivity to tylosin or other macrolide antibiotics (e.g., erythromycin).
- Pregnancy: Safety in pregnant animals has not been established. Weigh the maternal benefit against the potential risk to the offspring. The caution reflects the absence of tylosin-specific data rather than a known class risk, since other macrolides are considered safe for use during pregnancy.
- Lactation: Tylosin is excreted into milk at concentrations up to five times higher than serum. Use only when the maternal benefits outweigh the potential risks to nursing offspring.
- Horses and hindgut fermenters: This drug is contraindicated in horses, in which severe and sometimes fatal diarrhea and colitis have been reported. Use with extreme caution, if at all, in other hindgut fermenters such as rabbits.
- Not for intravenous use: This route should be avoided. Intravenous injection has been associated with shock, depression and dyspnea.
- Small exotic species: Do not administer orally to rodents or rabbits.
Drug Interactions
Limited interaction data are available for tylosin.
The following interactions have been reported or are theoretical in humans or animals receiving tylosin. One source records that no drug interactions have been reported for animals, and another that they are not well documented in small animals.
- Bentonite: Avoid giving tylosin and bentonite together in feed or drinking water; significant reductions in tylosin plasma concentrations and overall exposure have been shown in chickens.
- Digoxin: May increase blood digoxin concentrations, resulting in digoxin toxicity.
- Injectable incompatibility: Do not mix tylosin injection with other drugs in the same syringe, as tylosin may precipitate.
- Hepatic enzyme inhibition: Unlike erythromycin and some other macrolides, tylosin does not appear to inhibit the same hepatic enzymes, and no cytochrome P450 interactions have been reported in animals.
Side Effects & Overdose
Side Effects
Tylosin is generally well tolerated in dogs and cats.
The most commonly reported adverse effects involve the gastrointestinal tract or occur following intramuscular administration.
- Injection site reactions: Pain and local reactions may occur following IM administration.
- Volume limit per site: Do not inject more than 10 mL at one intramuscular site, to avoid local reactions.
- Gastrointestinal effects: Mild gastrointestinal upset, including anorexia and diarrhea, may occur.
- Severe diarrhea in other species: Oral administration to ruminants, or administration by any route to horses, may induce severe diarrhea.
- Long-term use: For oral treatment of colitis in dogs, tylosin has been administered for several months with safety.
Overdose
Tylosin is relatively safe in most overdose situations, and dogs have demonstrated a wide margin of safety following oral administration.
- Toxicity: Dogs have tolerated oral doses of up to 800 mg/kg.
- Long-term administration: Oral doses of up to 400 mg/kg for 2 years produced no organ toxicity in dogs.
- Margin of safety: The oral LD50 in pigs is greater than 5 g/kg and the intramuscular LD50 is 1 g/kg, which is the scale behind the wide margin described above.
- Management: For suspected overdose, consultation with a veterinary poison consultation center is recommended.
Key Notes
Practical points for the clinical use of tylosin in dogs and cats:
- Antibacterial activity: Tylosin has good activity against mycoplasmas.
- Spectrum of activity: It has an antibacterial spectrum similar to erythromycin but is generally less active against bacteria.
- Limits of the spectrum: Tylosin has some activity against Campylobacter species but is not a recommended first-line agent for them.
- Availability in small animals: Nothing is labeled for either species. The available veterinary products are labeled for cattle, swine, poultry and honey bees, so every small-animal use is extra-label, and the soluble powder dispensed for dogs and cats is a poultry and pig formulation.
- Antimicrobial stewardship: Tylosin is classified as category C (Caution) for antimicrobial stewardship, and macrolides are designated Critically Important for human medicine and Veterinary Critically Important agents.
- Other names for this syndrome: Antibiotic-responsive diarrhea is also described as tylosin-responsive diarrhea and small intestinal dysbiosis; the terms are used synonymously. The older term small intestinal bacterial overgrowth (SIBO) is no longer used for the primary syndrome, as it rested on quantitative culture that PCR-based methods could not confirm.
- Judging a trial of therapy: Response is judged clinically rather than at a fixed endpoint. The controlled evidence used a 7-day course and response in that first week is the signal to continue; recommended courses then run 4 to 6 weeks for antibiotic-responsive diarrhea, 6 weeks for dysbiosis and 8 to 12 weeks for chronic antibiotic-responsive enteropathy, where tylosin is described as the drug of choice over metronidazole for the same course length.
- Long-term treatment can induce dysbiosis: Sustained courses of tylosin or metronidazole have been found to induce a long-term dysbiosis in dogs with antibiotic-responsive diarrhea that is very difficult to correct and persists for more than 6 months after treatment is stopped; recent studies link that induced dysbiosis to a poor long-term prognosis in these dogs.
- Inflammatory bowel disease: Tylosin is described as adjunctive treatment for IBD in dogs in the formulary literature, while the disease texts state that antibiotics are generally not indicated for treatment of IBD and may significantly disrupt the gut microbiota even after administration is discontinued.
- Half-life and dosing interval: Elimination is rapid, at about 54 minutes in dogs, and tylosin is time-dependent, which is why the shorter intervals are used for colitis while once-daily regimens rely on activity within the gut.
- Tartrate and phosphate salts: The two are not interchangeable. Oral bioavailability is about 35% for tylosin tartrate and about 14% for tylosin phosphate, and tylosin tartrate is equal to 800 micrograms of tylosin base per milligram.
- Storage: Store in a tightly sealed container, protected from light, at room temperature, 25°C (77°F). Tylosin is unstable in acidic media below pH 4.
- pH and activity: Antibacterial potency is enhanced in an alkaline medium.
- Monitoring: No specific laboratory monitoring is necessary during treatment.
- Laboratory interference: Macrolides may cause falsely elevated ALT and AST values on colorimetric assays, and may alter fluorometric determinations of urinary catecholamines.
- Resistance and gut flora: Over 50% of Enterococcus faecalis isolates from healthy dogs were resistant to tylosin in one study, and tylosin may increase the concentration of enterococci in the jejunum.
- Measuring the powder: A spoon is not necessarily accurate for the soluble powder; where it is unavoidable, 1 level teaspoon contains about 2.5 to 2.7 g of tylosin.
