R8 - a web-based health survey
of fancy rats in Norway

I am greatly in debt to all of you who filled in the form!
The survey was announced at NTF's (Norwegian Fancy Rat Society) forum and a closed web ring for rat fanciers. Reminders were posted at both forums regularly throughout the survey. The results will be published by and by in NTF's periodical Gnag. 14 days after the publishing date the articles will be published on my web pages.
The form was active between 2008.03.24 - 2008.04.24.

Link to the form (inactive, and in Norwegian only)

Link to the data from the survey (in Norwegian only)

Part I of VI

Goal: mapping common health problems and veterinary services received by fancy rats i Norway, publishing in Gnag with comments
Criteria for participation: sole owner by a fancy rats from the age of approximately eight weeks at the latest, or before adult fur is fully developed, and until the rat was at least six months old.
Announcement: at NTF’s forum and at the closed web ring.
Duration: 1 month before the form was closed against further entry.

The survey was not announced at for instance Dyresonen, Dyr.no, or TIN (other Norwegian forums about pets and fancy rats). Dyresonen and Dyr.no have few postings about rats, (0 and 4 new threads during the month prior to the survey) and the members are frequently referred to NTF’s forum for questions and answers about fancy rats. TIN was a relatively new forum when the survey started. Most if not all users of TIN were also users of NTF’s forum, the closed web ring or both. Not all users of NTF’s forum were members of the closed web ring and vice versa.
The recruitment for the survey is not fully representative of fancy rat owners in Norway. This was evident from the start, as the survey was not announced through pet shops. Mass surveys of this type was not feasible and besides, experience points to a low cost-efficacy. I relied on pet shop rats to be well represented in the material from NTF’s forum and the closed web ring. Among others I was hoping to receive sufficient data for a comparison between the health of rats from private breeders and rats bought at pet shops.

All in all I received information about 69 rats, of which 17 (25%) had not had health problems.

69 rats may seem a decent collection, but in truth it is a quite small number! With a total of 69 rats we can only hope to see the very commonest diseases. It is also difficult to glean anything meaningful by comparing subgroups like for instance, standads coated rats with dubble rex/fuzz/hairless rats. When looking at the results the age of the rats must be taken into account. 22 of the rats ( ca. 1/3) was registered as between 6 and 12 months. 25 rats were between 12 and 18 months. 20 rats were over 18 months, and 2 were lacking information about their age. This means that most of the rats in this survey are relatively young. Accordingly the survey mostly maps health problems of fancy rats at their peak in life.

Fig. 1: Owner-reported health problems in % of the problems

Several of the health problems may have surfaced more than once for each registered rat.

Battle wounds accounted for 23% of the registered problems (21 rats).
I had made a programming error, so that both minor and major battle wounds were registered under one heading!
According to the use of veterinary services, most battle wounds are minor. Even if they are a concern for a large number of rats, disease is probably a more serious problem. It is likely that a number of scratches and minor wounds go undetected or have been forgotten. As male rats usually have more violent conflicts than the females, having more than 2,25 does pr. buck in the material is likely to lower the average. Another concern is that rats who spend most of their time alone or with only a few cage mates are probably less prone to be involved in fighting. The survey does not ask about the living conditions of the rats. One rat only was reported with wounds or damage not likely to have been caused by fighting".

Aggression against rats and people made for 6% of the health problems, concerning 3 and 2 rats among the 69. This means that five rats had behaviour problems grave enough for many owners to contemplate re-homing, neutering, or euthanasia. Even if the percentage is only rough measure, this means approximately one rat per litter is aggressive, taking the average litter size to be 10. This is on the high side compared to literature, for instance petrats.org.

None of the rats in the survey were castrated, put to sleep or re-homed because of aggression toward other rats. Two of the rats were euthanised for being aggressive towards humans.

It was hardly surprising that Airway problems came high on the list of health troubles. This category represented 18% of all reported health problems (20 rats). I will return to airway problems in part IV of the article.

Ear infections are a known and feared complication of upper respiratory infections or stuffy nose in rats. 4% of the rats, that is 3 of them, were affected. Interestingly only one of these rats was registered with airway problems. Both rats without respiratory problems but with an ear infection were treated for it by a vet. In these cases the cause of symptoms was not just a speculation by the owner.

Abcesses/skin problems was only registered in one rat among the 69. This was surprisingly low – I have had an abcess in two of the twelve bucks that have resided with me for longer or shorter periods. (None of them fulfilled the criteria of inclusion for the survey.)

Mites and lice were about equally bothersome, with 13 and 11% of the reported health problems. This means 12 and 10 rats, respectively. Naturally the probability of being affected with mites and lice increases with a high number of introductions or social contact with other rats. A rat owner with a lot of rats, having been infected with these little pests, will greatly affect such a small survey. Do take the percentages with more than a pinch of salt...

Concerning tumors 9% of the rats were regisred with mammary tumors (8 females). 9% is a considerable slice of the population. Actually, in this survey it means 16% of the does were affected. Pituitary tumors on the other hand is believed to occur more often in bucks. When two males were registered with pituitary tumor (3% of total health problems) this gives a probability of 10% of the male fancy rats. "Other tumors" also make up 3% of the health problems. These tumors were registered in two does. The questionary and the raw data from the survey can be viewed at http://matmor.info

Part II of VI

Veterinary services
The picture is not quite the same as for health complaints. Possible causes:

In this survey 25 rats had never had veterinary care (36% of the animals).

Not unexpectedly the most common cause of buying veterinary services was respiratory problems. 17 rats had been examined for this. That is three rats fewer than the number reported to have respiratory problems. The difference may be due to the fact that a short bout of nasal sounds may not always lead to a visit at the vet. Possibly the owner has only reported treatment for a concurring ear infection or the rat may have been critically ill and was put down rather than treated. There is always the chance that the wrong button was pushed.

Next comes treatment against mites and lice. The two categories have been combined here. As a whole 22 rats were reported to be affected. We already know from the owner-reported health concerns that there were 12 rats with mites and 10 with lice. All the rats with registered mite or lice infestation are registered with veterinary services to remedy the problem. This should not be taken for granted. For instance: a sick and weakened rat may show evidence of vermin shortly before death.

The number three reason for paying for veterinary services is euthanasia. 10 were registered. 5 rats had received wound care not connected to surgical procedures. 4 rats were medicated for ear infection, 2 for urinary infection and another two had had their nails cut at the vet. One rat was treated for an eye infection. One rat had received painkillers, one had had its teeth cut, one had been operated for a tumor, one had had "other surgery" and one had had a sample taken.

Fig. 2: Owner reported veterinary services as % of the services

Several of the services may have been required more than once for each rat.

No sterilization/castration, amputation, pharmacological intervention against aggression, birth assistance, diahorrea or "other" was registered among the answers. It is a good sign that the "other" category was not used. This indicates that common health complaints were well covered by the form. Under self reported health concerns two rats were registered in the "other category. Discussions at NTF’s forum about the use of the "other" category revealed that these two rats were treated prophylactically against a respiratory infection. Accordingly these rats should have been registred under Veterinary services.

Table I: Comparison between reported health problems and veterinary services
Health concern Owner-reported Treated by a vet
Lice and mites 22 22
Injuries 22 5
Respiratory trouble 20 17
Tumors 13 1
Aggression 5 0
Ear infection 3 4
Abcesses, skin problems 1 1
Eye infection 0 1
Injuries are both fighting wounds and other injuries. Possibly 6 rats were treated for injuries, not 5: The one rat registered with "injury, not related to fight" is also registered with ”other surgery”.

Concerning the greater number of reportedly medicated rats compared to reported health complaints no self evident explanation comes to mind. It is possible that the person filling in the form have simply forgotten to press the right button. Perhaps they thought it was not necessary to register health conserns when the same concern could be inferred from treatment. Maybe the owner felt the rat was treated for a disease it did not have. Naturally, people may have pressed the wrong button in the veterinary service section too. The disagreements are a warning against taking these results literally.

Part III of VI

Causes of death
19 rats were registered as dead in the first part of the form, 22 rats were registered in the part containing causes of death. I assume that there have been an under-reporting of dead rats. It is harder to recall health facts from long ago, as may be the case with owners who have had rats for a number of years. The results from the query match the average age of death in Ratbase fairly well. The ”most common” age to die 18-30 months, which means 1,5 – 2,5 years. The age of death seems to be a little higher here as more rats died in the age cathegory 24-30 months than in the 18-24 months. The difference is so small it could be due to chance. Table II: Age at death for 19 (22) rats
6-12 months12-18 months18-24 months24-30 months> 30 monthsNot specified
As no rats had age >30 months at death, the cathegory 30-36 months and > 36 months were joined in the table.

One rat was registered as living at home (that is, alive), died naturally, and with no cause of death. One rat was registered as living at home, died naturally, and with a cause of death. One rat was registered without status (dead, living at home, re-homed) but as euthanized and with a cause of death.

Age at death must must be seen together with the age of the age of the living rats in the survey. For instance, 3 (2) rats are registered as alive in the age group 30-36 months. (The numbers in parentheses represent an uncertianty because of an inconsistency between the answers for the same rat.) Of the 69 rats in the survey there are bound to be rats that will be more than 30 months when they die. According to the "Age at death"-table, only 1/3 af the rats died before the age of 18 months. However, 47 of the 69 rats are below 18 months and only one rat among the 69 are registered as re-homed. It seems as if young rats are strongly over-represented in the survey, compated to the natural population curve of pet rats.

Fig. 3: Owner-reported causes of death and euthanasia

The 22 rats have been registered with 26 causes of death or euthanasia.

Reading about rat healt problems at NTF's forum, one is easily lead to believe that respiratory infections are the most common causes of death among pet rats. The survey points in a different direction. Tumors are registered as cause of death four times more often than airway problems (12 times agains 3). One of the rat had both mammary tumor and other tumors. Among the 11 rats with tumor listed as cause of death, five reached the age of 24-30 months. Four became 18-24 months, one 12-18 months and one was only 6-12 months.

Concerning "age" as a (contributing) cause of death, the younges rat with this description was only 12-18 months. It is possible for such a young rat to show ageing, but it is a moot question if this rat may have had an underlying disease giving the appearance of premature ageing. Respiratory problems and aggression will be described in later parts. Side effects/medicating errors, Other infections and Other only apply to one rat each.

The participants were also asked how the rat died, if it was dead. The rats i this material were largely euthanised as opposed to dying naturally. However, according to the answers to which veterinary services rat owners use, only 10 of the 18 euthanised rats were put to sleep by a vet. I doubt that home euthanasia is this common. Most likely the concentration of the participants was flagging towards the end of a long list of questions. If home euthanasia is as common as the survey suggests, this is quite remarkable.

Table III: Death by...
EuthanisedNatural deathAccident

The sample is too small to see if there are any differences between the "Death by.." cathegories.

Part IV of VI

Airway troubles
Airway troubles and nasal noises are so frequently commentet upon on rat foras, I felt it was worth adding some additional, specific questions to the survey. From a total of 69 rats, 29 rats were described to have had airway problems. some interesting information did come of it. For instance it was my belief that most rats had respiratory trouble early. According to this material that is not the case. The probability that a rat will develope its first airway problems, serious enough to warrant a visit to the vet, is roughly the same for each 6 month cathegory up to and including 18-24 months. The differences are so small it is better to talk about a 10% probability for each age class.

Table IV: Age at first visit to the vet because of a (suspected) respiratory infection
Age0-6 months6-12 months12-18 months18-24 monthsDon't remember
Percentage = percentage of rats that had reached the age group

None of the rats above 24 months were registered with airway troubles. As there were only 12 rats in this age group this may have been due to chanche. Also, the "don't remember" rat is more likely to have been old than young.

According to this survey it seems as if the probability of having had at least one respiratory infection increases with age. A rat who becomes over two years old have between three and four times the chance of having had (at least) one, as opposed to a rat between 6 and 12 months. luftveisinfeksjon øker med alder. This ratio does not change much between the 12-18 months and 18-24 months range, but the numbers are uncertian.

Table V: Rats with at least one airway infection at different ages
Age6-12 months12-18 months18-24 months 24 monthsDon't remember
Percentage = percentage of rats of a given age group

Table VI: Occurence/seriousness of airway troubles
IllnessNasal noises1 time2-3 timesChronicDon't remember
Noone had marked ”don't remember” in the form, but one rat was registered with improvement after treatment without having been registered as ill. This is the rat I've put in the ”don't remember” cathegory.

Rats with airway problems have been treated with antibiotics (19), immunosuppressives (1), and ”other” (1). None were treated with anti-asthmatics or anti-allergy medication. Seven rat were registered as ”not treated.” According to the form, one of them had never had symptoms from the airways and should not be counted. The remaining six were registred with nasal noises. This means that only two of the eight rats registered with nasal noises were treated for airway problems. Some rats evidently have nasal noises that their owners do not see as requireing treatment.

The cathegory ”ill 0 times” was superflous as it was possible to tick off ”never airway trouble”. It ought to have been a cathegory for "nasal noises > 2 days". Better testing of the query form could have weeded it out.

Three of the rats taken to vets on suspicion of airway infection did not get a diagnosis for a respiratory problem. Maybe the rat did not have an airway infection. However, it may be that many vets pay little regard to upper respiratory infections and only diagnose respiratory infections based on lung abnormalities.

No rats were euthanized directly at first consultation due to respiratory problems. Of the 19 rats that received treatment for airway infections, 12 became healthy during or after the first bout of treatment. One became worse. Two were healthy after an extended treatment. Three did not get well, but their health improved. The last rat was in the cathegory "don't remeber". Actually, only 17 rats were registered here although 19 supposedly received treatment. A question on the NTF's forum revealed the reason: two rats were treated prophylactically, that is, to avoid being infected by other rats.

As for airway problems as a cause of death som dødsårsak, the box was ticked off for three rats. All these rats were euthanized, and none of them had regained their health quickly after the first treatment. Two of them were registered with chronic respiratory problems, the third had had two to three infections. One was euthanized at 6-12 months, another in the age group 18-24 months, whereas the the age of the third rat was not remembered. This rat probably became at least 18-24 months old, as "age" was listed as one of the causes of death. For the youngest rat the airway problems were given as only reson. All three had their first airway infection before the age of 12 months.

Matmor, original 2008.06.03
last change 2009.05.04