Cephalexin Antibiotic Use in Egg Laying Duck

Asked February 8, 2020, 2:29 PM EST

One of our ducks got a deep cut on its bill and the vet issued a prescription for Cephalexin. The duck is only 10 weeks old and not yet producing eggs, but the Vet gave a verbal and written warning that by using this antibiotic the duck's eggs would never be fit for human consumption and that upon doing so humans could get sick and/or die!! I have found various references to antibiotic use in egg laying poultry, and the need for a waiting period after use, including specific reference to the use of Cephalexin be allowed. But in no case have I found such an extreme caution that the eggs could never be consumed again or risk illness or death. Do you have any information on this topic?

Santa Cruz County California

3 Responses

According to PoultryDVM - http://www.poultrydvm.com/drugs/cephalexin

Cephalexin (Keflex) is a first-generation cephalosporin antibiotic used mainly for deep skin infections, such as bumblefoot. It is effective against susceptible bacterial infections, mainly those that are associated with Gram-positive organisms.

Egg Withdrawal Period:
In the United States, Ireland, and the United Kingdom, cephalexin is approved for use in laying poultry producing eggs intended for human consumption when it's given in accordance with each product manufacturer s label directions; where it has a 0-day egg withdrawal period.

Drug Form
Available as an oral suspension (25-100 mg/ml)Dosage50-125 mg/kg IM, PO q6-12h

I have not found any research that says otherwise.

Dear Dr. Jacob,

Thank you for your response to my question about Cephalexin.

Can you please clarify the meaning of "0-day egg withdrawal period"?

Does that mean that there is no waiting period after the completion of Cephalexin, and the duck's eggs can be consumed immediately?

Also, in general, are cephalosporin antibiotics know to accumulate in eggs?

Are there known risks of any type of antibiotic use with egg consumption?

Thank you.

JT Fodor

Some antibiotics can NOT be used in hens laying eggs for human consumption. The proper use of any medication is on the label that package the medication comes in. Always follow the instructions on the label.
0-days means no withdrawal time. If there is no withdrawal time, that is an indication that there is no build up of the medication in the meat or eggs of the animal receiving the medication.

Information with regards to human patients:

  • Cephalexin is not metabolized in the body.
  • Route of elimination - Cephalexin is over 90% excreted in the urine after 6 hours by glomerular filtration and tubular secretion with a mean urinary recovery of 99.3%. Cephalexin is unchanged in the urine
  • Half life - The half life of cephalexin is 49.5 minutes in a fasted state and 76.5 minutes with food though these times were not significantly different in the study.
  • Clearance - Clearance from one subject was 376mL/min.
  • Symptoms of overdose include blood in the urine, diarrhea, nausea, upper abdominal pain, and vomiting. An overdose is generally managed through supportive treatment as diuresis, dialysis, hemodialysis, and charcoal hemoperfusion are not well studied in this case.
  • Cephalexin has not been shown to be harmful in pregnancy and is not associated with teratogenicity.
  • Cephalexin is present in breast milk, though infants may be exposed to <1% of the dose given to the mother.
  • The effects of breast milk exposure to cephalexin have not been established and so caution must be exercised and the risk and benefit of cephalexin use in breastfeeding must be weighed.
  • Cephalexin has not been studied for carcinogenicity or mutagenicity.
  • Cephalexin has no affect on fertility in rats.
Did find an old article that states:
"Cephalosporins, like penicillins, are a sub-group of betalactams derived from fungi (Cephalosporium acremonium) (Vaden & Riviere, 2001). First-generation cephalosporins such as cephalexin are primarily effective against Staphylococcus spp., Streptococcus spp., Escherichia coli, Proteus mirabilis, and Klebsiella spp. Following oral administration of cephalexin to chickens, the drug is widely distributed and found in high concentrations in the bile, suggesting hepatic metabolism (Kitagawa et al., 1988). Cephalexin appears to preferentially deposit in egg yolk, and residues can be long lasting (Kitagawa et al., 1988)."
The article said that there were residues in the yolk of treated chickens after 21 days.

Kitagawa, T., Gotoh, Y., Uchihara, K., Kohri, Y., Kinoue, T., Fujiwara, K. & Ohtani, W. (1988) Sensitive enzyme-immunoassay of cephalexin residues in milk, hen tissues, and eggs. Journal of the Association of Official Analytical Chemists, 71, 915–920.
"Application of the method to CEX drug residues detected 30 ng/mL in milk, 60 ng/g in egg yolk, and 400 ng/g in hen tissue."

As far as I can tell, cephalosporin is NOT approved for use in poultry so the vet gave it off-label. He is legally liable if anyone gets sick, which is why he probably said you can never it the eggs again.

The results I could find are contradictory. Since it is only one duck, you can go on the side of caution the same as the vet. Based on the results with humans I didn't see a problem, but I guess I have to cover myself too and say don't eat its eggs.