Rodents farmed for pet snake food


  • There are be­tween 4.2 mil­lion and 7.8 mil­lion pet snakes in the world.

  • 160 mil­lion to 2.1 billion ver­te­brates are kil­led for pet snake food ev­ery year. Most of the ver­te­brates seem to be farmed mice.

  • Feeder mice are kil­led when they are any­where be­tween 48 hours and more than 9 months old. Most seem to be slaugh­tered when they are 3–4 weeks old.

  • Farm­ing of feeder an­i­mals seems to in­volve con­sid­er­able suffer­ing be­cause they are of­ten liv­ing in cramped and pos­si­bly un­san­i­tary con­di­tions, which don’t have shelters to hide in, lack daylight and ac­tivi­ties.

  • I haven’t figured out what pos­si­ble in­ter­ven­tions in this space could be par­tic­u­larly promis­ing. It’s pos­si­ble that the prob­lem is not very tractable.

In this ar­ti­cle, I first es­ti­mate the num­ber of an­i­mals raised for pet snake food in the world. Then I dis­cuss some welfare con­cerns of these feeder ro­dents by com­par­ing the con­di­tions in which they are raised to the ones recom­mended for pet mice. Fi­nally, I brain­storm about pos­si­ble in­ter­ven­tions.


This ar­ti­cle is a part of a se­ries of ar­ti­cles by Re­think Pri­ori­ties about an­i­mals farmed for var­i­ous pur­poses. We are also plan­ning to write about fish farmed for fish stock en­hance­ments, and con­sid­er­ing writ­ing about the mor­tal­ity of farmed food an­i­mals. Fi­nally, we will cre­ate a list of es­ti­mates of num­bers of an­i­mals kept in cap­tivity for var­i­ous pur­poses. After that, we may cre­ate a similar list of es­ti­mates of num­bers of wild an­i­mals hu­mans af­fect in var­i­ous ways. The main goal of the se­ries is to un­cover sources of an­i­mal suffer­ing that other or­ga­ni­za­tions could tackle with cost-effec­tive in­ter­ven­tions.

After writ­ing this ex­plo­ra­tory ar­ti­cle about feeder ro­dents, I re­main largely un­cer­tain about the scale and es­pe­cially the tractabil­ity of this prob­lem. I look for­ward to read­ing opinions about it in the com­ments.

Es­ti­mat­ing how many an­i­mals are kil­led for snake food per year

In this sec­tion, I’ll pro­duce two differ­ent 90% sub­jec­tive con­fi­dence in­ter­vals of num­bers of ver­te­brates kil­led for pet snake food and com­bine them into one:

  • I first es­ti­mate that there are 4.2–7.8M snakes bred to be pets in the world and that on av­er­age they are fed 0.6–1.8 ver­te­brates per week. I then use these num­bers to es­ti­mate that 160M–580M ro­dents are kil­led for pet snake food per year.

  • I then look at some figures of frozen mice sold in the U.K. from the Fed­er­a­tion of Bri­tish Her­petol­o­gists and use them to es­ti­mate that 540M–2.1B ro­dents are kil­led for pet snake food per year.

  • Fi­nally, I make some hy­poth­e­sis about why the two es­ti­mates differ so much, and com­bine the two con­fi­dence in­ter­vals into one by tak­ing the lower bound from the first es­ti­mate and the up­per bound from the sec­ond es­ti­mate.

For brevity, in the ar­ti­cle I use K for a thou­sand, M for a mil­lion, and B or a billion. Many de­tails of the es­ti­ma­tions can be seen in the Guessti­mate model. Read­ers who are un­in­ter­ested in the de­tails of the calcu­la­tion can skip this sec­tion.

Num­ber of pet snakes

I haven’t found any es­ti­mates of the num­ber of pet snakes in the world, but I have found some es­ti­mates for var­i­ous coun­tries:

  • Ac­cord­ing to the UK’s Pet Food Man­u­fac­tur­ers’ As­so­ci­a­tion’s (PFMA) sur­veys, in the UK there were

  • Ac­cord­ing to the Amer­i­can Ve­teri­nary Med­i­cal As­so­ci­a­tion (2012), there are 1.15M snakes in the U.S., owned by 550K house­holds. Ac­cord­ing to the same source, in 2007 there were 586K pet snakes in the U.S. Publi­cly ac­cessible in­for­ma­tion did not ex­plain how these num­bers were es­ti­mated.

  • ENDCAP (2012): “in­sid­ers es­ti­mate ap­prox­i­mately 250K boids and pythons and 100K ven­omous snakes are kept in pri­vate house­holds in Ger­many.”

  • This Pul­tizer Cen­ter ar­ti­cle claims that “it is es­ti­mated that up to one one mil­lion peo­ple own ex­otic pets in China. Th­ese pets are defined as non-tra­di­tional ones, such as snakes, mon­keys, crocodiles, spi­ders, and trop­i­cal birds that are sourced from threat­ened ecosys­tems across the world.” It also claims that own­ing ex­otic pets is quickly be­com­ing more pop­u­lar in China.

  • A sur­vey by An­i­mal Medicines Aus­tralia found that there are ~415,000 rep­tile pets in Aus­tralia (sam­ple size was 2K re­spon­dents).

  • An Ir­ish Ex­am­iner ar­ti­cle claims that “Ire­land is home to 100K rep­tile pets, in­clud­ing deadly snakes and crocodiles.”

  • This quora thread sug­gests that pet snakes may be rare in In­dia.

  • A New York Times ar­ti­cle claims that “Ex­otic rep­tiles and am­phibi­ans be­gan surg­ing in pop­u­lar­ity in the early 1990s, not only in the United States but also in Europe and Ja­pan.” I haven’t found any other men­tions of pet snakes in Ja­pan.

  • Var­i­ous ar­ti­cles men­tion that in In­done­sia snakes are some­times kept as pets, as well as used for food, perfor­mance, and mas­sage.

Us­ing this in­for­ma­tion and some other in­for­ma­tion, I es­ti­mated that there are be­tween 3.8M and 6.9M pet snakes in house­holds around the world. See my guessti­mate model for the es­ti­ma­tion. The model in­cludes guess­ing the num­ber of snakes per 1000 peo­ple in coun­tries for which I couldn’t find statis­tics.

Some snakes that are bred to be pets are in pet stores and snake breed­ing fa­cil­ities. For ex­am­ple, in Black­pool, UK (pop­u­la­tion 140K) there are at least two shops that sell snakes. I vis­ited one of them and counted 126 snakes on its shelves, which is al­most 1 per thou­sand peo­ple. This shows that the num­ber of snakes in pet shops is sig­nifi­cant. I guess that the per­centage of such snakes that are yet to be pur­chased is some­where be­tween 3 and 20%. With this taken into ac­count, I es­ti­mate that there are 4.2–7.8M snakes that are bred to be pets.

Aver­age num­ber of an­i­mals fed to snakes

How of­ten snakes are fed de­pends on species. It seems that for all species, young snakes should be fed smaller mice more of­ten. For ex­am­ple, ac­cord­ing to a Rep­ ar­ti­cle, Corn Snakes have to be fed 1–3 smaller mice ev­ery 7–10 days un­til they are 18 months old (num­ber and size of feeder mice de­pend on age). Ball Pythons should be fed ev­ery 5–7 days when they are young. How­ever, snakes spend most of their time be­ing adults. This page lists the five most pop­u­lar pet snake species. Here is how of­ten each of them should be fed as adults:

It’s pos­si­ble that some own­ers choose to feed adult snakes mul­ti­ple smaller mice rather than one big mouse/​rat. Or that some peo­ple feed them more of­ten than guides sug­gest. Man­ual of Ex­otic Pet Prac­tice men­tions that “snakes are of­ten overfed in cap­tivity.” This in­for­mal poll shows that many own­ers feed one ro­dent per week and quite many feed more. I also asked how of­ten snakes should be fed at one rep­tile store and I was told that al­most all of their snakes are fed one mice of ap­pro­pri­ate size per week, while few big­ger snakes are fed more of­ten.

Note that mice are not the only an­i­mals snakes eat. A PetHelpful ar­ti­cle claims that there are pet snakes that eat chicks, fish, in­sects, eggs, and rep­tiles. VCA An­i­mal Hospi­tals claims that the most pop­u­lar pet snakes usu­ally eat prey such as mice, rats, ger­bils, and ham­sters. Larger pet snakes will also eat whole rab­bits. At the ex­treme end, this itv news re­port about pos­si­bly the longest pet snake in the UK claims that it eats 3 rab­bits per week.[1] Based on all this in­for­ma­tion, I guess that on av­er­age pet snakes eat 0.6–1.8 ver­te­brates per week, which is 31 to 94 ver­te­brates per year.

Num­ber of an­i­mals kil­led for snake food each year (first calcu­la­tion)

To calcu­late it, I mul­ti­ply the num­ber of snakes in the world by the num­ber of an­i­mals they eat per year. I also guess that 3%–20% of snakes kept to be pets are in pet stores and breed­ing fa­cil­ities. After tak­ing that into ac­count, I get a 90% sub­jec­tive con­fi­dence in­ter­val that there are 160M–580M an­i­mals fed to pet snakes per year.

An al­ter­na­tive es­ti­mate that uses frozen ro­dents sales

I found some sources that di­rectly say how many frozen ro­dents are sold. They are much higher than I ex­pected:

  • This In­de­pen­dent ar­ti­cle claims that 180M rats and mice were raised in the U.S. in 1999 and that 93% of them were sold as rep­tile food (other 2% were sold as pets, the rest were used in re­search). It also claims that there is still a sig­nifi­cant short­age of ro­dents. Th­ese figures are es­pe­cially sur­pris­ing be­cause it seems that snakes are be­com­ing more pop­u­lar in the U.S.,[2] but it could be that they were briefly very pop­u­lar around 1999. The ar­ti­cle also men­tions that there are 20M rep­tile own­ers in the U.S., but I’m not sure I trust this claim. This HSUS doc­u­ment claims that “more than 3.9 mil­lion house­holds in the United States con­tained one or more pet rep­tiles or am­phibi­ans in 2000”. As­sum­ing an av­er­age house­hold size of 2.6, that is 10M own­ers, not 20M. And some of the 10M only kept am­phibi­ans.

  • Fed­er­a­tion of Bri­tish Her­petol­o­gists’ (FBH) web­site claims that over 1M frozen mice are sold each week for snake food in the UK and that ad­di­tional ~3.5 tons of frozen ro­dents are im­ported from out­side the EU each month. It’s based on a 2008 sur­vey by REPTA which I was un­able to find. FBH also used this and other sales of spe­cial­ists rep­tile food data to de­ter­mine that there are “over 1.2 mil­lion house­holds were home to over seven mil­lion pet rep­tiles” in the UK. Even though FBHs es­ti­mates are cited by Tele­graph (a re­spected news source in the UK), I’m not sure I trust this con­clu­sion be­cause PFMA’s sur­veys con­sis­tently es­ti­mate that the num­ber of rep­tile pets in the UK is less than a mil­lion.[3] It’s pos­si­ble that FBH them­selves don’t know why so many frozen ro­dents are be­ing sold or that they are (in­ten­tion­ally or not) in­flat­ing the figures.

  • 2012 FBH’s brochure claims that an es­ti­mated 2M frozen mice are sold for snake food in the UK each week and also cites REPTA as the source. That is 104M per year for the UK alone. Note that these num­bers are only for sold frozen mice, but some peo­ple feed their snakes rats, day-old chicks, or other an­i­mals.

Even if FBH’s es­ti­mate of the num­ber of pet rep­tiles is in­cor­rect, it’s pos­si­ble that the sales of rep­tile food data that was used to pro­duce the es­ti­mates is cor­rect. How­ever, in that case, there is an in­con­sis­tency be­tween PFMA’s es­ti­mate that there are 200K–400K pet snakes in the UK and FBHs claim that 1M–2M frozen mice sold are sold each week be­cause that would be 3–8.5 frozen mice per snake per week—much more than av­er­age snake eats. Similarly, if we as­sume that in 1999 there were as many snakes in the U.S. as in 2007 (586K) and that figures in the In­de­pen­dent ar­ti­cle are cor­rect, that would mean that in the U.S. there were 5.5 ro­dents raised per snake. There are mul­ti­ple ways to ex­plain these in­con­sis­ten­cies:

  • Con­trary to what FBH claims, many frozen mice are used for things other than snake food. Ac­cord­ing to a Pet Age ar­ti­cle, ”the feeder ro­dent in­dus­try may be the life­blood for snake breed­ers and snake keep­ers, but it also serves an­i­mal col­lec­tions at zoos and mu­se­ums and some ravenous rap­tors at wildlife re­ha­bil­i­ta­tion fa­cil­ities.” The ar­ti­cle also claims that bald ea­gles can eat 15 frozen mice in a sit­ting and that crows and swal­low-tailed kites eat small mice. What is more, some lizards, frogs and other pets also eat ro­dents.

  • There are more snakes in the U.K. and in the U.S. than sur­veys sug­gest be­cause sur­veys don’t cap­ture a few own­ers who own many snakes. The com­bined sam­ple size of PFMA’s sur­veys is more than 24K. Even though it is big, it could be in­suffi­cient. If few own­ers own many snakes, PFMA’s sur­veys might have failed to catch any such re­spon­dents and con­se­quently un­der­es­ti­mated the num­ber. Ac­cord­ing to the PFMA’s sur­veys, snake-own­ing house­holds on av­er­age own 1.8 snakes. Figure 5 in Clark (2012) shows that out of 656 re­spon­dents who owned a snake, 367 owned 6 six or more of them. Sur­vey did not have a rep­re­sen­ta­tive sam­ple be­cause it was “dis­tributed over the rep­tile keeper’s net­works on the in­ter­net,” but it still in­di­cates that there are peo­ple who own many snakes.

  • Some sold frozen mice end up not be­ing fed to any an­i­mal. In the U.S., hu­man food waste is es­ti­mated at be­tween 30–40 per­cent of the food sup­ply. Maybe some pet food is wasted as well. Frozen mice are cheap, es­pe­cially if they are bought in bulk. Own­ers could be buy­ing more than they need but prob­a­bly not much more be­cause it takes up freezer space.

  • Force-feed­ing snakes. Some ar­ti­cles men­tion that some own­ers overfeed their snakes be­cause they want them to be­come big­ger.

  • In­stead of feed­ing adults snakes big­ger mice, some own­ers choose to feed them many small mice. This would in­crease the num­ber of used mice a lot but I haven’t seen much ev­i­dence of that hap­pen­ing.

  • Mor­tal­ity rates dur­ing trans­port and in pet stores.

In the end, even though I don’t trust FBH’s num­bers, I don’t trust my es­ti­ma­tion in the pre­vi­ous sec­tion much ei­ther, and the FBH’s num­bers are the only di­rect ro­dent sales num­bers I found.

In the guessti­mate model, I use FBH’s num­bers to pro­duce an al­ter­na­tive calcu­la­tion. First I calcu­late the num­ber of ro­dents fed to pet snakes in the U.K. To do that, I mul­ti­ply FBH’s figures (1M–2M frozen mice per week which is 52M–104M per year) by the pro­por­tion of frozen mice that are sold as food for pet snakes. As men­tioned be­fore, frozen mice can also be used to feed to some other pet an­i­mals, and used at zoos and wildlife re­ha­bil­i­ta­tion cen­ters. I don’t know the value of this pro­por­tion is, but I guess that it is be­tween 50% and 97%. I then di­vide it from the pro­por­tion of ver­te­brates pro­duced for pet snake food that is frozen mice. As men­tioned be­fore, some snakes are fed rats, chicks, rab­bits or other an­i­mals but farmed mice seem to be by far most pop­u­lar, at least in the U.K. Con­se­quently, I guess that the pro­por­tion is be­tween 80% and 95%. Fi­nally, I use my es­ti­mate that 4–9% of world’s pet snakes are in the UK, to es­ti­mate that 540M–2.1B ver­te­brates are kil­led for pet snake food in the world each year. Note that I as­sume that the ra­tio of snakes to mice in the UK and the world is the same, which might not be cor­rect. Fur­ther­more, I could have in­cor­rectly es­ti­mate the pro­por­tion of pet snakes that live in the UK.

This es­ti­mate barely over­laps with my pre­vi­ous es­ti­mate that 160M–580M an­i­mals fed to pet snakes per year. This makes me doubt both of my mod­els, so I take the lower bound from one es­ti­mate, and up­per bound from the other, and end up with a 90% sub­jec­tive con­fi­dence in­ter­val of 160M–2.1B ver­te­brates are kil­led for pet snake food in the world each year. For com­par­i­son, Prize (2014) es­ti­mates that around 118M an­i­mals are used for ex­per­i­ments, al­though it claims that this is likely an un­der­es­ti­mate. It seems that most of the ver­te­brates fed to snakes are farmed mice, though I’m not sure what the per­centage is, es­pe­cially out­side of the U.K. and the U.S.

Snakes farmed for other purposes

Pet snakes are not the only snakes in cap­tivity. This Busi­ness In­sider ar­ti­cle claims that one Chi­nese village breeds 3M snakes per year for food and venom (which is used for medici­nal pur­poses). Snakes are also farmed for their skins. I was un­able to get an es­ti­mate of how many snakes are farmed for other pur­poses in the world due to the lack of statis­tics. It’s also un­clear how many of these snakes are fed farmed ro­dents. Here is all the ev­i­dence about the feed­ing of snakes that are bred for pur­poses other than com­pan­ion­ship that I have found:

  • Ac­cord­ing to Aust, et al. (2016), in China and Viet­nam they are usu­ally fed wild-har­vested nat­u­ral food (­phibi­ans and ro­dents), waste pro­tein from other in­dus­tries (e.g., poul­try and pork), for­mu­lated diets (re­con­sti­tuted waste pro­tein), and snake meat for King Co­bras.

  • This Time Out ar­ti­cle about the Chi­nese village that breeds 3M snakes per year men­tions “walk­ing past buck­ets of dead chicks and frogs used for feed­ing the snakes.”

  • This news ar­ti­cle talks about a snake farm in Thailand that breeds mice to feed them. The prac­tice was called into ques­tion by lo­cal offi­cials who were con­cerned that this may vi­o­late a newly passed An­i­mal Welfare Act. It’s un­clear what was the re­s­olu­tion and whether such prac­tice is com­mon.

Over­all, it’s un­clear how many of snakes farmed for other pur­poses are fed farmed mice but it seems that farmed mice is not the most com­mon food for these snakes.

Lifes­pan of breeder mice

To de­ter­mine the scale of suffer­ing en­dured by feeder an­i­mals, we need to con­sider not only the num­bers but also how long on av­er­age an­i­mals live and suffer in fac­tory farm con­di­tions.

Hardin (2013) shows that these ro­dents can be slaugh­tered when aged any­where be­tween 48 hours, to 9 or more months. It also claims that “most feeder ro­dents typ­i­cally are sold be­fore or shortly af­ter wean­ing.” Mice are weaned be­tween 21–26 days of age. Judg­ing from what I see in on­line stores, I guess that a con­sid­er­able num­ber of mice are also kil­led at a differ­ent age (both younger and older). A vet­eri­nar­ian told me that at one zoo, some small rap­tors/​rep­tiles were fed younger mice, but in gen­eral, mice were kil­led (or fed al­ive) at 8–10 weeks of age

Welfare concerns

In this sec­tion, I look at con­di­tions in which feeder ro­dents live in farms and com­pare them with the con­di­tions that are recom­mended for lab­o­ra­tory and pet mice. Then I briefly dis­cuss con­cerns about live feed­ing.

This sec­tion was re­viewed by a vet­eri­nar­ian who wished to re­main anony­mous. They con­firmed my im­pres­sion that con­di­tions seen in the videos and pic­tures be­low are bad. They also told that con­di­tions for feeder ro­dents they wit­nessed at a zoo and at a pet store were similar.

Con­di­tions for breeder mice

I’ve only found sev­eral videos and pic­tures of con­di­tions in feeder mice farms:

  • Video 1: a short video of a large feeder mice farm.

  • Video 2: a man ex­plains how he runs a small scale mouse and rat farm

  • Video 3: the video de­scrip­tion says that it’s “mice at a farm crammed in a lit­tle box be­fore be­ing served to snakes.” Con­di­tions look very bad. Some of the mice seem to be already dead. It’s un­clear if these are con­di­tions in which they were grown as well.

  • Video 4: an­other video that might be rep­re­sen­ta­tive of how most feeder ro­dents are raised.

  • Video 5: in the be­gin­ning shows how some peo­ple may raise few rats for their own snakes in pretty good con­di­tions. Then shows a larger scale farm that is similar to oth­ers.

  • Pic­tures 1 and 2 (see be­low): I found these pic­tures at where both of them were ti­tled “White Mice grown for live rep­tile feed on farm” and up­loaded by the same au­thor. Pre­sum­ably, the first pic­ture shows how one of the con­tain­ers seen in pic­ture 2 looks in­side. The pic­tured con­di­tions seem very bad.

Pic­ture 1:

Picture 1

Pic­ture 2:

Picture 2

Lack of space

RSPCA guidelines for keep­ing pet mice ex­plain that “wild mice can have very large ter­ri­to­ries. Mice need suffi­cient space to dis­play nat­u­ral be­hav­iors and give con­trol/​choice over their en­vi­ron­ment.” claims that the min­i­mum cage size for a pair of pet mice is 45cm x 30cm (1350 cm2) with at least 25cm depth.

Fawcett (2012) has these guidelines for the hous­ing of mice in sci­en­tific in­sti­tu­tions:

“As a guide, en­clo­sures should al­low for a min­i­mum floor area of 250cm2 for a sin­gle housed mouse, a min­i­mum floor area of 500cm2 for two mice and en­sur­ing a min­i­mum floor area of 60cm2 per ad­di­tional adult mouse when mice are housed in larger groups.”
“As a guide, the op­ti­mal size for a group of adult mice is three to five for fe­males and three for males.”

In video 1 there are 50 mice in a box that seems to be smaller than 1800cm2, maybe even 1000cm2. In some other videos the situ­a­tion ap­pears to be bet­ter, but in video 3 and pic­ture 1 it is much worse.[4]

Liv­ing in their own feces

A vet­eri­nar­ian said that in most of the videos a lot of fe­ces can be seen within the bed of all the draw­ers. Pet mice usu­ally choose a toi­let cor­ner, but it doesn’t always hap­pen. I find it un­likely that all ro­dents pick the same cor­ner when liv­ing in such cramped con­di­tions. And even if they do, fe­ces might ac­cu­mu­late quickly. In video 2, the man claims that he cleans con­tain­ers ev­ery “week or week and a half.” Ac­cord­ing to this page, this might be in­suffi­cient even when mice are not cramped.

Lack of shelters

Fawcett (2012) gives de­tailed in­struc­tions for shelters that have to be pro­vided to lab mice. Similarly, RSPCA guidelines ex­plain that “mice are a prey species; they’re highly mo­ti­vated to stay near cover.” It claims that they need tubes for hid­ing or sleep­ing in, shelters with mul­ti­ple ex­its where mice could hide when they wish, and avoid any con­fronta­tion with other cage mates. In all cases, cages for feeder mice don’t in­clude any shelters.

Liv­ing in such cramped con­di­tions with­out places to hide might be caus­ing a lot of stress to mice, es­pe­cially if some of them be­come ag­gres­sive. Both, RSPCA and Fawcett (2012) claim that mice should always be mon­i­tored to check that cage mates do not be­come ag­gres­sive. I haven’t seen any in­di­ca­tion that this is be­ing done in breed­ing fa­cil­ities.

Lack of activities

Fawcett (2012) claims that “en­vi­ron­men­tal en­rich­ment is es­sen­tial for all mice.” Similarly, RSPCA says that “run­ning wheels can be pro­vided but shouldn’t be the only en­rich­ment.” Lack of any en­rich­ment in con­tain­ers is con­cern­ing.

Lack of daylight

RSPCA also claims that mice need nat­u­ral daylight. How­ever, in all videos, they are only ex­posed to ar­tifi­cial light and in video 1 they seem to spend their time in dark­ness.

Pos­si­ble lack of bed­ding and nest­ing ma­te­rial in some cases

RSPCA claims that “mice need bed­ding ma­te­rial to dig/​ab­sorb mois­ture from urine/​fae­ces” and nest­ing ma­te­ri­als are needed to help body tem­per­a­ture reg­u­la­tion. Bed­ding ma­te­ri­als seem to be pre­sent in videos 1, 2, 4 and 5, but they seem to be lack­ing in video 3 and in pic­ture 1. How­ever, it’s pos­si­ble that video 3 does not show the en­vi­ron­ment in which mice spend most of their time. I can’t tell whether nest­ing ma­te­ri­als are pro­vided in any of the videos.

Pos­si­ble lack of vet­eri­nary care

It’s un­clear whether ro­dents re­ceive vet­eri­nary care when they need it, but I’d be sur­prised if they do. A vet­eri­nar­ian said that even when sold as pets, mice are of­ten filthy and don’t always re­ceive ad­e­quate med­i­cal care.

Lack of reg­u­la­tions (at least in the U.S.)

Hardin (2013) claims:

“Un­like other ro­dents, rats and mice are not gov­erned by the An­i­mal Welfare Act (USDA 2013) and thus are not sub­ject to fed­eral reg­u­la­tions on caging, trans­porta­tion and han­dling. Nonethe­less, suc­cess­ful pro­duc­ers gen­er­ally ad­here to pro­fes­sional stan­dards of hus­bandry. As with any in­dus­try, there have been a few op­er­a­tions with un­san­i­tary con­di­tions and sub­stan­dard care and hous­ing, along with a few un­usual in­ci­dents, which has cast a nega­tive light on feeder ro­dent pro­duc­ers. Ad­di­tion­ally, feeder ro­dents have been vec­tors in zoonotic out­breaks, e.g., salmonel­losis, lym­pho­cytic chori­omenin­gitis virus (LCMV), rat bite fever.”

The fact that mice con­di­tions are not reg­u­lated in any way makes me con­cerned. How­ever, in the U.S., no fed­eral laws gov­ern the con­di­tions in which farmed an­i­mals are raised ei­ther.

Feed­ing live prey

All the ar­ti­cles I’ve seen ad­vise against feed­ing snakes live prey. Ro­dents can in­jure (some­times even kill) the snake and cause in­fec­tions.[5] De­spite that, it seems that a sig­nifi­cant num­ber of own­ers are do­ing it be­cause wher­ever snake food is dis­cussed, live feed­ing is dis­cussed as well. I haven’t found any statis­tics on what per­centage of an­i­mals are fed al­ive,[6] but ac­cord­ing to Hardin (2013), the ma­jor­ity of an­i­mals are sold frozen (rather than live). It claims that this “avoids degra­da­tion in the qual­ity of live an­i­mals from trans­port stress.” In ad­di­tion to stress dur­ing trans­port, an­i­mals may suffer while they are kept in a pet store. In this ar­ti­cle, a per­son who used to work at a pet store told that she wit­nessed ill or in­jured feeder mice on a daily ba­sis. She told that other work­ers did not care about their welfare, once dis­miss­ing her con­cern about an open wound be­cause it was “just a feeder mouse.”

Fi­nally, there is also suffer­ing dur­ing feed­ing.[7] As I un­der­stand it, most of the time snake will kill prey very quickly. By look­ing at 20 YouTube videos of live-feed­ing, Cooper and Willi­ams (2014) es­ti­mated that “the time to death as es­ti­mated by ces­sa­tion of any move­ment was 62 ± 29 sec­onds for mice, 54 ± 21 sec­onds for rat”. How­ever, in some cases, snake may not be hun­gry, and a ro­dent could be stuck in a tank with a preda­tor for days.

Pos­si­ble interventions

Here are some pos­si­ble in­ter­ven­tions to re­duce the suffer­ing of these an­i­mals:

  • Rais­ing aware­ness about the suffer­ing in­volved in the rais­ing of feeder mice could re­duce the num­ber of peo­ple will­ing to buy snakes. On the other hand, it might also raise aware­ness about snakes as pos­si­ble pets and could lead to more peo­ple ac­quiring pet snakes. Over­all, I don’t think it’s a good ap­proach.

  • Im­prov­ing con­di­tions for breeder mice via cor­po­rate cam­paigns (similarly to the way it’s done in the food in­dus­try).[8] It might be a bad idea be­cause such cam­paigns could make it seem that keep­ing ex­otic an­i­mals as pets is ac­cept­able, which could in­crease their quan­tity.

  • Cor­po­rate cam­paigns that en­courage pets stores to stop sel­l­ing feeder mice and snakes. This pe­ti­tion is an ex­am­ple. Gen­eral pet stores need the sup­port of gen­eral an­i­mal lovers, but spe­cial­ized rep­tile stores may not care. It could also raise aware­ness of pet snakes as an op­tion which is bad.

  • Lob­by­ing to ban on the sel­l­ing pet snakes, or farm­ing an­i­mals for pet food. The fact that some an­i­mal or­ga­ni­za­tions man­age to ban fur farm­ing in cer­tain coun­tries shows that such achieve­ments can be pos­si­ble. What is more, there are at least some similar laws passed already:

  • Lob­by­ing to ban sel­l­ing snakes in pet stores, or to dis­play them in pet store win­dows. Sales of feeder an­i­mals in pet stores could maybe be banned with the same ini­ti­a­tive. It could de­crease snake sales. Similar bans were im­ple­mented for other an­i­mals:

    • Van­cou­ver banned pet stores from sel­l­ing cats, dogs, and bunnies

    • Toronto banned the sale of cats and dogs in pet stores

    • There are plans to ban third-party sales of pup­pies and kit­tens in the U.K.

    • Dis­play­ing dogs and cats in pet store win­dows was re­cently banned in Spain. The ar­ti­cle claims that “we are cer­tain that it will ap­ply to other an­i­mals. For ex­am­ple, maybe fish, spi­ders, snakes, birds, and more, soon.”

  • Lob­by­ing to in­crease le­gal re­quire­ments for own­ing and sel­l­ing snakes might be pos­si­ble. In Aus­tralia, They seem to be quite com­plex already. That may de­crease the num­ber of pet snakes.

  • En­force­ment of ex­ist­ing stan­dards. I found four cases of feeder ro­dents be­ing con­fis­cated due to un­ac­cept­able liv­ing con­di­tions. One case was in Scot­land where, fol­low­ing an in­spec­tion by a char­ity, a man was jailed for con­tra­ven­tions of the An­i­mal Health & Welfare (Scot­land) Act of caus­ing un­nec­es­sary suffer­ing to ro­dents he raised to feed his pet snakes. Other three cases are in var­i­ous U.S. states. One of them re­sulted in the clos­ing of a farm of about 30,000 mice and an ar­rest. Con­di­tions for feeder ro­dents are not reg­u­lated by fed­eral U.S. laws, so I’m un­sure what reg­u­la­tions were used as a ba­sis of all these con­fis­ca­tions. In any case, there could be ways to make sure that more such pros­e­cu­tions hap­pen. It would elimi­nate the worst farms and en­courage breed­ers to en­sure less cruel con­di­tions for feeder ro­dents.

  • Lob­by­ing to have more le­gal re­quire­ments for how feeder ro­dents are raised. Could be the same re­quire­ments as for lab an­i­mals. The claim is easy to make: why would we treat an­i­mals of the same species differ­ently just be­cause they are used for a differ­ent pur­pose?

  • En­courag­ing al­ter­na­tive feed sources. Aust, et al. (2016) men­tions some farms us­ing re­con­sti­tuted waste pro­tein. Maybe a small pro­por­tion of own­ers would be open to switch­ing to some­thing like that, but I find it un­likely.

  • Creat­ing an or­ga­ni­za­tion that grows feeder an­i­mals in very good con­di­tions. It would ei­ther sell them at a higher price to own­ers who care about an­i­mal welfare or partly sus­tain it­self from dona­tions.

My in­tu­ition is that try­ing to ban the sale of snakes in pet stores is the most promis­ing in­ter­ven­tion, but I’m very un­cer­tain. I also don’t know if any of these in­ter­ven­tions would be cost-effec­tive com­pared to ACE’s top char­i­ties.


[1] It also claims that the snake might live for up to 30 years. That means that over its life­time it might eat over 4K rab­bits.

[2] Ac­cord­ing to AVMA (2012), there are 1.15M snakes in the U.S., owned by 550K house­holds. Ac­cord­ing to the same source, in 2007 there were 586K pet snakes in the U.S. This 2018 ar­ti­cle claims that herps (non-avian rep­tiles and am­phibi­ans) are be­com­ing in­creas­ingly pop­u­lar and main­stream and that sales of their food are in­creas­ing. This 2013 Pet Age ar­ti­cle claims that “over the past 25 years, the feeder ro­dent in­dus­try has grown sub­stan­tially”.

[3] Fur­ther­more, I find it hard to be­lieve that there are more pet rep­tiles than dogs in the UK.

[4] The box in video 3 is tall but as this page (writ­ten by a hob­by­ist) ex­plains:

“tall aquar­iums are a poor choice, for in­stance, be­cause mice can’t en­joy the space—they need room to run around, not look up at. Not only that, but air cir­cu­lates poorly in a tall aquar­ium.”

The page also recom­mends to use a 20-gal­lon aquar­ium for a group of five or six mice.

[5] In a pet store I was told that feed­ing live mice is ille­gal in the UK due to an­i­mal welfare con­cerns. If that is re­ally the case, it shows that leg­is­la­tive progress in this area is pos­si­ble.

[6] Ac­cord­ing to slide 72 of this pre­sen­ta­tion:

“34% (83/​246) of Min­nesota Sal­monella cases who re­ported rep­tile ex­po­sure re­ported feed­ing their rep­tile some type of ro­dent – 87% (72/​83) of snake own­ers re­ported feed­ing them ro­dents. Among those who fed ro­dents: – 59% (47/​80) fed frozen ro­dents – 41% (33/​80) fed live ro­dents.”

How­ever, this is not a rep­re­sen­ta­tive sam­ple and live mice may be more prone to cause salmonella.

[7] Cooper and Willi­ams (2014) de­scribes welfare is­sues with live feed­ing:

[8] I think that such cam­paigns could gain pub­lic sup­port be­cause the suffer­ing of feeder ro­dents is more ob­vi­ously un­nec­es­sary than the suffer­ing of an­i­mals raised for hu­man food or used for ex­per­i­ments. Non-veg­e­tar­i­ans would feel less cog­ni­tive dis­so­nance about sup­port­ing it. Fur­ther­more, fewer peo­ple doubt ro­dents’ abil­ity to suffer than chick­ens’ or fish abil­ity to suffer. Ro­dents are also of­ten fea­tured in cam­paigns against an­i­mal test­ing which is a cause that has re­ceived a lot of at­ten­tion rel­a­tive to its size. This in­di­cates that peo­ple can care about ro­dents even if they don’t seem like the most pop­u­lar an­i­mals.


The Amer­i­can Ve­teri­nary Med­i­cal As­so­ci­a­tion. 2012 U.S. Pet Own­er­ship & De­mo­graph­ics Source­book.

Aust P., Tri N. V., Na­tusch D., Alexan­der G. J. 2016. Asian snake farms: con­ser­va­tion curse or sus­tain­able en­ter­prise?

Clark, B. 2012? A Re­port Look­ing at the Rep­tile Keep­ing Hobby, Those Who Want it Banned and Why?

Cooper, J. E., Willi­ams, D. L. 2005. The Feed­ing of Live Food to Ex­otic Pets: Is­sues of Welfare and Ethics

ENDCAP (2012). Wild Pets in the Euro­pean Union.

Hardin S. 2013. Best Man­age­ment Prac­tices for Feeder Ro­dent Pro­duc­tion and Distri­bu­tion.

Prize, L. 2014. A global view of an­i­mal ex­per­i­ments 2014.

Fawcett, A. 2012. Guidelines for the hous­ing of mice in sci­en­tific in­sti­tu­tions.

This es­say is a pro­ject of Re­think Pri­ori­ties. It was writ­ten by Saulius Šimčikas. Thanks to Daniela R. Wald­horn, Mar­cus A. Davis, and Peter Hur­ford for re­view­ing drafts of this post and mak­ing valuable com­ments.

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