American Fancy Rat & Mouse Association

Showing and Risks: Biosecurity Importance and Exposure Risks

By Karen Robbins

At a recent AFRMA show, one exhibitor reported sick rats after the show. One rat was tested 17 days after the show (he did not have any symptoms at the show) and was positive for several things including Sialodacryoadenitis virus (SDAV), Cilia-Associated Respiratory Bacillus (CAR Bacillus/CARB), and Seoul Hantavirus (SEOV). Symptoms in the sick rats were respiratory-type symptoms, labored breathing, one rat had swollen glands, and some died. The person reporting the sick rats had entered the show then met with several other people after the show at a hotel to exchange rats. New rats were brought in from one other person (these rats were not at the show). One other person reported two animals they bought that were only at the exchange got sick as well (their rats tested negative [NEG] for SEOV). Everyone that exhibited rats at the show were contacted and no one else reported sick rats, only the one person that went to the get-together and got new rats there. It sounds like the exchange is where the illness(es) had been contracted and NOT at the show—the show was just used as a time to meet up with others afterwards.

It was said online that x-number people were having problems but that number is not the same as the people themselves stating they are having problems. Unfortunately, people will read these type of statements as fact and not question it. We cannot go with hearsay but with facts and our research showed only 2 people had sick rats.

Test results we received from other exhibitors that attended the show and/or the after-show get-together all reported NEG results for SEOV testing.

The rat that was tested right after the show was handled at the show by several visitors to the show. At the shows the animals are not to be handled by anyone other than the owner, health checkers, and the judges (they are to be kept in their solid-sided carriers when not being judged). Sale animals should not have anyone handle them other than people serious about buying them. When around other rodents whether at a pet shop, friend, breeder, show, get-together, etc., a person should always be thinking they are potentially bringing something in, so it should be standard practice to shower and put on clean clothes when you get home and wait a few hours before handling/visiting your stock. Always assume there’s a contagious risk in any contact outside the home colony.

Sialodacryoadenitis Virus (SDAV)

SDAV takes 1–2 weeks for symptoms to show up in newly infected rats and sometimes the rat that is the source may not get as sick as the new rats that got infected from this rat. This disease causes respiratory symptoms, sneezing, runny eyes and nose (red tears), swollen salivary glands (looks like they have the mumps), and sensitivity to light, With this virus, as long as there are new animals brought in or new babies born in the rattery, then the infection will continue and rats that survive will be carriers with intermittent outbreaks. In Pathology of Laboratory Rodents and Rabbits 4th Ed. page 125, it says that Prior exposure to the SDAV provides protection against the development of the disease upon reinfection for up to 15 months. However, to stop this in a person’s rattery and clear the virus, one MUST QUARANTINE and STOP BREEDING for a minimum of 2 months after the last litter born and/or newest rat(s) brought in. They will need to retest their stock to make sure the virus is clear before resuming breeding, selling, and showing. This virus is susceptible to detergents, disinfectants, and drying so doing a thorough cleaning will eradicate it from the environment.

Cilia-Associated Respiratory Bacillus (CAR Bacillus/CARB)

CAR Bacillus is found in wild rodents. It is transmitted by direct contact with an infected animal. This is also a respiratory disease with sneezing, weight loss, ruffled fur, and runny eyes and nose (red tears) and is similar to Mycoplasma pulmonis infections. PCR testing is preferred to follow up positive serology testing. Good sanitation and disinfection should remove this from the environment.

My experience with animals that survive a serious infection of both SDAV and CARB do not do well after and die early so they should be euthanizied instead of letting them suffer. Only the healthiest ones that did not have a serious illness should be kept for further breeding.

Seoul Hantavirus (SEOV)

According to the research articles, SEOV is not transmitted from humans to rats but via a bite (most common), saliva, urine or feces (direct contact) from a contagious animal and takes 2 weeks or more for antibodies to show once infected. Testing should be done on new stock 4 weeks after their arrival. Kittens have immunity up to 10–15 weeks so testing should be done on adult animals over 12 weeks of age (the one kitten that was shown at the show tested NEG for SEOV). This is most common in older rats and in males. Studies have found increased aggression in males with SEOV. If a breeder’s rats test POS for SEOV, retesting is to be done every 4 weeks until all rats are NEG (after euthanizing the POS ones each time). The biggest concern for the rats is the SDAV and CARB as those will have symptoms and kill rats and are highly contagious to other rats. SEOV won’t kill rats and it doesn’t make the rats sick—you won’t know they have it unless you test all your rats as not all may be POS for it. Rats can test POS for antibodies but not be contagious/shedding at the time of the test. Shedding occurs anywhere from 10–40 days after initial infection then decreasing over the next few weeks. Last year with the Seoul Hantavirus outbreak there were a few ratteries that only had 1 or a few POS and had a POS living with a NEG for months without infecting it. These results have shown sampling (only testing a portion of the colony) is not sufficient to rule a rattery negative for SEOV.

Getting Stock

Buyers need to be careful of who and where they get rats (and mice) from (should always buy from a reputable breeder, not a backyard breeder, pet shop, feeder breeder, or sales list), should always do the proper quarantine (QT), buy supplies from a lab supply if possible, and not take in wild stock of any kind (orphan, injured, etc.; if you buy from someone that has wild stock, make sure they test them for multiple pathogens and are clear and get copies of their results).

Quarantine IS Necessary

Again, we can’t stress enough the importance of proper QT before a show (any new animals brought into your rattery/mousery must go through a minimum 12-week quarantine period before being entered in a show) and especially after a show (animals at a show should be QT for a minimum of 4 to 12 weeks afterwards). [We have changed the QT times effective September 15, 2018.]

General Testing of Stock/Wild Rodents

Bringing animals in solid-sided carriers, not allowing animals to be handled at the shows other than by the owner, health checkers, and judges, and doing proper QT before and after a show is imperative.

Breeders should be testing new stock brought in (especially if there is any sickness/death in the first few weeks) as some diseases have no symptoms. Breeders should test their animals so they have a starting point/reference of what they have/don’t have, then any time new animals are brought in, to test those so they can see if they are bringing in something new and what to do about it. Testing should be for multiple pathogens—Mycoplasma, Seoul Hantavirus, SDAV, CAR Bacillus [CARB], Sendai, Parvo [KRV], Leptospirosis, Rat Minute Virus [RMV], Lymphocytic Choriomeningitis virus [LCMV], Rat Bite Fever, etc.—most panels will have more than this. Invariably when there are sick rats there is more than one pathogen at work. If any illness shows up while new animals are in QT, then testing definitely needs to be done, treatment/culling if necessary, then retest. Some people routinely test once a year even if they haven’t brought in new animals.

If there is any incident of wild rodents getting into a person’s rattery/mousery or the animals’ cages or their food or bedding, then rodent proofing the building and cleaning things up and testing the existing stock would be needed. With any kind of wild rodent there is the possibility of them having parasites or diseases that can be harmful or deadly to other pet rodents or humans.

Getting supplies from a lab supply and not a pet shop/feed store is best as a lab supply has to adhere to strict cleanliness standards to sell to labs.

Illness Prior To An Event

If a person has health problems in their rattery/mousery within a couple months prior to a show or other event (remember new animals you bring in must go through a minimum 12-week QT period), they should not take any animals to that show or event. The stress of going to a show/event just brings everything to the surface and makes things worse and potentially infects other animals.

Entering Stock

When entering animals in a show or taking them to an event, don’t take your best breeding stock so if something happens to them or they bring in an illness and die or must be euthanized, it won’t wipe out your breeding program. Some breeders will only take stock to be shown that is then all sold so they don’t bring anything back. Others will have a no return policy on ones they sell (or euthanize any coming back) so they don’t chance anything coming into their rattery/mousery.

Testing To Show

We had discussed requiring exhibitors/sellers to test their rats (and mice) before being shown/sold but that is not possible as rats (nor mice) are able to be vaccinated against diseases. The test would only show results on the day of the test—new rats/mice could have been brought in afterwards, contact with infected rats/mice could have happened and an illness brought in, or wild rats/mice could have gotten into the animal’s food, bedding, or cages. The Exhibitor/Seller’s form is required so we know where people have gotten critters, any testing done, the results, and any treatment, and stress the importance of testing, being careful of where new animals are obtained, and doing proper QT. Those that take in wild rodents will not be allowed to enter a show until test results have been done on those animals to show they are clear of all contagions.

Meeting up with people after a show or other event at a different location to exchange animals that were not at the show is usually never a good idea. Also, extreme care must be made if attending sales events where many people go just to exchange animals as it is common to have infected animals there.

All exhibitors are to assume liability and responsibility to research the many zoonotic and other diseases that rodents may carry and pass on to humans or other rodents. You are showing at your own risk.

We want our shows to be safe, fun events for both exhibitors and visitors. It is not only up to the event staff to do everything they can to minimize the spread of diseases, but the exhibitors and visitors as well. Visitors must adhere to our Do Not Touch signs at the shows regarding the animals but DO talk to the exhibitors and staff, support the various sales tables, and have fun watching the judging. You can’t be too careful when it comes to animals of any kind, even if vaccinations are available for that species. *

References/Further Reading:

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September 22, 2018