Bringing in animals from another source means bringing in their whole health status, including diseases that may show no signs at the time of purchase. That is why the new biosecurity chapter of the Terrestrial Animal Health Code, adopted by the WOAH World Assembly at its 93rd General Session in 2026, calls for keeping introductions to a minimum and assessing the health status of the source population. ^{[1, 5]} We cite the text the Code Commission submitted for adoption, which was adopted with minor wording changes.

The chapter adds that animals of unknown or different health status should go through a monitored isolation period of sufficient length before joining the population, during which tests or treatments may be applied to reduce the risk of spreading pathogens. ^[1] The point is not a token “quarantine” but a path that prevents contact until mixing has been shown to be safe.

What should you check before the consignment arrives?

The most important decision is made before shipment. The University of Maine Extension quarantine checklist advises buying from as few sources as possible, only from herds with health standards equal to or higher than your own, and asking the herd veterinarian about pre-purchase testing. ^[3]

Before collecting the animals, confirm:

• Movement papers, animal identification and test results are complete before loading. ^[3]
• The available health history of the source herd; your vet can contact the seller’s vet to share health information. ^[2]
• Where the animals will be received, who will handle them, and the route for the vehicle, equipment and waste.
• A clear plan for any animal that tests positive. ^[2]

Keep two levels apart: the official import and quarantine requirements set by the competent authority in your country, such as the Ministry of Climate Change and Environment in the UAE or the Ministry of Environment, Water and Agriculture in Saudi Arabia, and the farm’s own isolation procedures to protect its herd. Meeting the first does not replace the second.

How should you set up the isolation area?

Effective isolation separates everything that carries infection, not just the location. SDSU guidance calls for no contact between new arrivals and the herd, including nose-to-nose contact and shared manure, water or feed, and for controlling the movement of equipment, vehicles and people between the two groups. ^[2]

The UMaine checklist sets out the site requirements: away from the main herd and high-traffic areas, or with a buffer of at least 6 feet (about 1.8 metres) between holding areas if that is not possible; easy to clean and disinfect; reserved for isolation only; with feeding and cleaning equipment that stays in the isolation area; and a disposal site for waste hay, bedding and manure kept separate from the farm’s compost. ^[3]

The WOAH chapter stresses controlled human access, with dedicated clothing and footwear and hand hygiene as a minimum when handling animals, and no sharing of equipment or clothing between populations; where sharing cannot be avoided, items are cleaned and disinfected before and after each use. ^[1] The Code’s land transport chapter likewise recommends cleaning vehicles and containers before reuse by removing manure and bedding, disinfecting them where there are concerns about disease transmission, and disposing of manure, bedding and animals that die in transit in a way that prevents disease spread. ^[4] So keep the unloading and vehicle-cleaning point well away from the herd’s pens and feed routes.

How long should isolation last?

No single figure suits every species and farm. SDSU guidance for beef cattle recommends at least 30 days and preferably 60, because a longer period allows acute disease to appear and animals to stop shedding, and keeps bred cows and heifers separate until they calve and their calves are tested. ^[2] The UMaine checklist gives a minimum of 14 days with 28 preferred, so that animals pass through the incubation and infectious periods of most contagious diseases. ^[3]

That difference between two reputable sources shows why the period should not be copied from one farm to another. The veterinarian sets it according to species, target diseases, the source’s history, the tests required and any official requirement that applies.

What should you monitor and record during isolation?

The UMaine checklist recommends observing animals daily for lethargy, lameness, coughing, nasal or eye discharge, skin lesions, diarrhoea, reduced feed intake, neurological signs and deaths, and caring for isolated animals last, after the rest of the farm. ^[3] During isolation, new animals are brought into line with the herd’s vaccination and parasite control programme. ^{[2, 3]}

For each group, record the purchase date, source, animal identification, treatments and health observations. ^[3] Add any breaches to the record: who entered without following the procedure, which tool was used outside the area, and how the breach was handled. The WOAH chapter expects each operation to have a documented biosecurity plan, with staff training and evaluation of compliance and effectiveness, routinely or after any significant change. ^[1]

Hypothetical example

A cattle farm is preparing to receive a group from a new supplier. Reviewing the route before arrival, the manager finds that the feed cart and cleaning tools are shared between the receiving barn and the herd, and that the same worker starts the morning round at the new barn because it is nearest the gate.

The manager changes the procedure: colour-coded dedicated tools, boots and an apron at the isolation door, and a new round order with isolation last. The vet is asked to set the period and tests before arrival, and the entry decision stays with the vet alone. In the second week the worker records that the feed cart was used once in both areas, and the vet reviews the effect of that breach on the entry date before approving it.

What should you do if signs appear in isolation?

Disease appearing inside the isolation area is not a failure of the procedure; it shows the procedure has done its job. What matters is that the response is written down in advance. The UMaine checklist recommends having a plan for animals that fail quarantine and considering vet-guided screening for diseases with long incubation periods or symptomless carrier phases. ^[3]

In practice, the procedure covers three points:

• Report any of the monitored signs to the vet immediately rather than waiting for the next round.
• Stop the clock until the vet has assessed the case, because signs may change the entry date for the whole group, not just the sick animal.
• Keep animals from different sources apart within isolation, as the checklist recommends, ^[3] so that one group’s problem does not spread to another.

The WOAH chapter lists detecting, isolating and diagnosing sick animals among the internal biosecurity measures, ^[1] and if the vet suspects a notifiable disease, the reporting procedures set by the competent authority in your country apply.

When can restrictions be lifted and the animal join the herd?

The entry decision follows completion of the period the vet set, receipt of the required test results, alignment of vaccination with the herd programme, and a review of the isolation and breach log. SDSU guidance says the herd veterinarian should guide these decisions and be consulted well before the animals arrive, not afterwards. ^[2]

The next cycle should not start until the isolation area has been cleaned and disinfected. SDSU guidance also notes that animals returning from shows, having mixed with other cattle, should be treated as new purchases. ^[2]

Conclusion

Design the reception of new animals as a single path that starts with the purchasing decision and ends with a veterinary sign-off on entry. Separate the new group in everything that carries infection, record observations and breaches daily, and leave the isolation period and testing to the herd vet and the competent authority’s requirements.