Use of antibiotics administered in water to pigs in the Post-VFD era

Basic use and management of water medications for pigs.

Since the VFD (Veterinary Feed Directive) came into effect on January 1, 2017, livestock producers have been implementing changes required for use of most antibiotics when delivered in feed or water (injectables are not affected).  Included in these changes, feed distributors are now required to have a valid VFD, written by the prescribing veterinarian, in order to prepare antibiotic-medicated feeds.  This requires additional paperwork that could, in some instances, delay a producer’s response to a disease outbreak.  As new livestock barns are being built, particularly in the swine sector, many producers have incorporated medicators into their water systems. This technology, when used to deliver antibiotics, bypasses the feed mill formulation step and can facilitate rapid mass treatment of herds during a viral or bacterial disease outbreak. Several antibiotics commonly used in pigs can be administered in water (Table 1).


Trade Name (Powder or Liquid)

% Active Ingredient

Dose mg/kg

Withdrawal Days


Amoxinsol (P)





Auromcyin Soluble (P)





Garacin Soluble (P)





Lincomix Soluble (P)





Neo128, Neo325, Neovet325 (P)





Terramycin 343 (P)





Sulmet (L)





Tetra-Bac-324 (P)





Denegard Soluble (L)





Pulmotil (L)





Tylan Soluble (P)




There are several things to consider when thinking about using water medication. In this article we describe some of the most important advantages and disadvantages of medicating through the water system. We also provide some helpful tips for implementing and maintaining a water medication system.

Advantages and disadvantages of water delivery of antibiotics

The most important advantages of water delivery of antibiotics, relative to delivery by injection or in feed, are related to convenience/ease of administration (saving time and labor), response time, and the fact that water delivery is stress-free (requires no restraint, no needles and no tissue damage/irritation at injection site).  Administering antibiotics via water to an entire barn full of pigs typically requires only a few minutes of one person’s time to add the appropriate amount of a soluble powder or suspended formulation to a proportioner (typically used in large facilities constructed more recently) or an overhead tank system (often used on small farms).  This saves labor, but could also save considerable time, when the alternative is injection of individual animals throughout the barn.  Though a veterinary client patient relationship (VCPR) and prescription for the medication are required, water delivery typically follows on-farm/internal standard operating procedures (SOPs) that obviate the step of obtaining medicated material from a feed mill.  This could save important time in the case of a rapidly moving outbreak.  In this manner, use of water soluble medication can stabilize or even prevent disease outbreaks.  Examples might include administration of penicillin to all pigs in a barn quickly when swine respiratory disease (SRD) is detected in a few pigs, and using lincomycin or tiamulin to prevent swine dysentery within the herd.

Since pigs frequently go off-feed very early after contracting a respiratory or gastrointestinal disease, the effectiveness of the in-feed medications may be compromised.  Pigs rarely stop drinking water, even in the midst of serious infection, so administering antibiotic by water can bypass this issue.  Water delivery can also be used for pulsed drug regimens, when that is appropriate; this can be used as part of a strategy to reduce antibiotic usage.  In addition, antibiotics mixed in feed sometimes have issues with attaching to calcium, phosphorus, and sodium molecules present in the feed, and this can reduce their effectiveness; these issues are less frequent and generally less serious in the case of water delivery.

Handling and administering injected antibiotics can cause stress in pigs (Dantzer and Mormede, 1983), which can exacerbate an already-weakened immune system in diseased pigs. Also, depending on the medication used, the chemotherapeutic response time may be slower when injected into the neck muscle as opposed to simply drinking water soluble medications (Yan and Gilbert, 2004).

A final advantage with water delivery is that the system itself, once installed, can be used to deliver other useful solutes, including electrolytes, probiotics and acidifiers (often used to control post-weaning scours associated with E. coli).

There are also several potential disadvantages to consider when administering water soluble medications, in addition to the added cost of equipment. Since all pigs in a pen are essentially “treated” when this method is used, it could be costlier if a high percentage of the pigs are healthy and don’t require or benefit from treatment.  There is also a considerable risk of wasting expensive medication in the water, as pigs tend to “play” with waterers. Also, palatability and water quality could impact the nature of the medication being used, and high calcium levels within the water supply has been reported to decrease the effectiveness of some tetracycline medications (Kemmerer, 2008). When administering water medication, ease and flow of the water lines must be monitored carefully; water delivery rate may vary considerably depending on location within a barn (Brooks and Carpenter, 1990).  Also, water lines need to be cleaned thoroughly following their use to deliver medication, in keeping with current FDA guidelines designed to limit drug residue in livestock animals (Animal Feed Safety System, and see Rozeboom, 2018).

Management and maintenance tips

Before making the decision to install a water medication system, a producer should also consider the management that is needed; why, how much time and how frequently will this system need attention.  Below are two short lists, insights and tasks; one for the maintenance of water lines and the other for managing the products going into the watering systems:

Water line maintenance:

  • A quick and simple way to check water flow is use a measuring cup and time how long it takes to fill up a cup of water for a pen waterer source (see table below).
  • When using water medicators, cleaning the water lines after each round of medication run through the lines is strongly advised.
  • Most medications result in the water becoming off-colored or even a completely different color. Take note after running clean water through the lines to ensure that color changes associated with medications are no longer evident.
  • Filters are commonly used to prevent the build-up of iron, chlorine, peroxide, and biofilm (which can provide a protected environment for pathogens that adversely affect pig health and performance).
  • Filters should be checked routinely; monthly for breeding herds and at each turn for finishing pigs.
  • If the water coming into the barn is considered “hard”, periodic use of an acidic descaler product to clean the water lines may be warranted, as filtering alone may not effectively control scale build-up.




Gestation/ Boars


Estimated Water Intake, gallons/pig/day





Recommended flow rate,
milliliters per minute (cups)

250-500  (1-2)

500-1,000  (2-4)

>1,000 (> 4)

>1,000 (>4)

Source: National Pork Board, Swine Care Handbook (2003 Edition), Brumm 2010 “Water Systems for Swine”.

Water Requirements By Phase

Production Phase

   Water Requirement


Flow Rate (Sec/pint)





2 to 3



3 to 5


Gestating Sows

3 to 6


Lactating Sows

2.5 to 7





Source: National Pork Board, PQA PLUS Site Assessment Guide (2015 Edition)

Management of products

  • Work with your veterinarian to make sure that VFD guidelines are adhered to in obtaining prescriptions for water administered antibiotic. Have an SOP readily available that is well understood and followed by all farm staff.
  • If in doubt, work with your veterinarian to confirm the diagnosis of disease and, ideally, the antibiotic sensitivity of the bacterial pathogen. This information can ensure that the best available antibiotic is used.
  • Pigs typically waste water trying to keep cool during the hottest part of hot days; drug wastage can be limited by pulse medicating in water during cooler times of the day.
  • Cup style drinkers can reduce water (and drug) wastage considerably relative nipple drinkers.
  • Make sure drug is fully dissolved in water prior to use.
  • Avoid drug residue issues by adhering strictly to directions provided on drug labels, extra-label instructions given to you by your veterinarian.
  • Make sure that your drinkers are maintained at the correct flow rate for the size of animals (Brumm, 2010).
  • Maintain your water system by following recommended testing and cleaning procedures.


Overall, water medications can be an effective means in the treatment and prevention of disease within a pig herd. Through personal experience of managing a wean-to-finish barn, water soluble medications decreased labor cost and pig stress and efficiently decreased the mortality rate from SRD and other diseases. Water medication systems can work well if appropriately managed and maintained.


Schulz, Lee L., and Christopher J. Rademacher. "Food and Drug Administration Guidance 209 and 213 and Veterinary Feed Directive regulations regarding antibiotic use in livestock: A survey of preparation and anticipated impacts in the swine industry." Journal of Swine Health and Production 25.5 (2017): 247-255.

Taylor, Graeme, et al. “Water Medication for Pigs.” The Pig Site, 5 June 2006,

“Group Treatment - Managing Pig Health and Treating Pig Dieases on” The Pig Site,

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