What is ammonia to our rabbits?
Ammonia is a highly hydrophilic base and has irritant properties that could damage the respiratory tract and eyes of rabbit and humans. If you can smell it while walking through your rabbit home, think how it is effecting your rabbits. In comparison to rabbits, the human sense of smell is rather poor. Once we are able to detect ammonia vapors, the level of ammonia is already too high in the rabbit atmosphere. In most cases, ammonia concentration in room is >50X ammonia concentration in the cage itself.
Ammonia is also one of the major causes that could affect the spread and growth of rabbit diseases. Persistent high levels of ammonia can damage the delicate nasal passages of rabbits and may causes lesion and abscess. The nares in the nose that filter out pathogens become damaged and often respiratory disease follows.
Heat and Ammonia
But in warm countries like Singapore, hot air resulting in ammonia turning into vapors that develop as a result of the breakdown of urine and is prevalent whole year round. Ammonia development increases with increased temperatures, thus, in a closed building such as a HDB home or apartment, this can cause a problem. Hot air rises to the top of the house, whereas ammonia is a heavy gas that drops down to the floor. But in Singapore, our HDB homes have a pretty low ceiling which cause the hot air build up near the floor and causes the ammonia to build up in the home. Do note that vast majority of chemical compound is most toxic at the higher temperatures (Keplinger et al, 1959).
Humidity and Ammonia
Humidity plays a role in ammonia generation as well as the level of damage it can cause to both the respiratory system of rabbits and the cages. High humidity (90%) reduces a rabbits ability to remove moisture from the respiratory tract (the only means of means of heat loss at high temperature), whereas low humidity (10%) does the opposite, increasing the incidence of upper respiratory tract infections(Clough and Gamble,1976). Both are not good for the mucous membranes of the respiratory tract of the rabbit. It is noted that ammonia generation rate from bedding increases daily at 75% relative humidity.(Riskowski, Harrison, Memarzadeh 2006).
How to rid of ammonia?
(1) Ventilation and Fans
Well ventilated homes are important to “odor-free” environment. (Munkelt 1938,1948; Runkle 1964). Effectiveness of ventilation is the measure of the immediate environment of the enclosure of the rabbit, which in Singapore is our HDB home or rooms. Passive ventilation will only helps if the air is ventilated out near the floor area where the ammonia concentration is the highest. It is good to have a good fans to blow clean air so that atmosphere air is moved quickly to get rid of the ammonia in the air.
(2) Temperature and Humidity
As temperature and humidity are the main factors in the ammonia vaporization, it is important to note that the best conditions for reduce ammonia generation is to house rabbits in air-conditioned rooms, where temperature and humidity are lower. Singapore is one of the many countries where humidity level is rarely drop below 75%, even in controlled environment such as air-conditioned room. As such, high humidity with high temperature environment is main concern for rabbits here as ammonia generation rate increases and ammonia toxicity is at its highest. It is good to a measuring unit to measure the humidity and temperature of the environment.
(3) More Frequent Cleaning
Cleaning rabbit cages or homes more often than normal will also help.By removing the urine and feces from the rabbit homes, you are decreasing the amount of ammonia can be generate in the surrounding area. Ammonia generation rate increases significant daily from uncleaned rabbit homes at 75% relative humidity (Singapore humidity = >90%). Increase cleaning frequency reduces the ammonia concentration and reduced anxiety of the rabbits to the owner (C Burn, A Peters,M Jay, G Mason 2006). New studies indicated that fungi activities also increases significantly due to material high humidity (Rylander,Foden, Ewaldsson, Reeslev 2009). Threshold value for ammonia in humans is 25ppm for 8hrs. At a study of 50ppm for 3hrs,respiration rate for rabbits drop 34% (Mayan, Merilan 1972) but in prolonged exposure to NH3, permanent irreversible damage to the lungs may be evident.
(4) Number of rabbits in a cage or room
In commercial rabbitry, modern ventilation systems are installed to control the evaporation and removal of NH3 from the rabbitry. However, this is not evident in modern homes in Singapore. They are not build to cater for removal of NH3 build-up in the room or cages. New studies indicate the cycle of cleaning of cage is shortened significantly with increased in the number of rabbits in a cage and room. It is advisable to only place a maximum 2 rabbits in a 4X4 playpen with another similar setup in a new HDB room layout.
(5) Beddings and Ammonia
Research has shown absorbent bedding helps to decrease ammonia levels. Most beddings have no effect on the ammonia generation despite differing absorption rate (Burns & Mason 2005). Bedding absorption capacity is not a good indicator of potential to maintain or release NH3. However, the type of bedding material affects waste physical properties, structure, NH3 adsorption, and release rates because of differences in water adsorption capacity, rate of moisture release, and ongoing biochemical processes (Kuczynski and Slobodzian-Ksenicz, 2002).
There are many different types of bedding in the market:
a) Pine/Cedar Shavings
Pine shavings have been taking a bad rap lately, despite many years of serving well as pet bedding. In a 1975 Sabine report on Cedar shavings, there were incidence of lower tumor occurrence in Sabine laboratory mice when it was transferred to Australia (that uses fir). However, NIH Heston 1975 conducted further investigation revealed that “there is no evidence that cedar shavings is carcinogenic”. It also indicated that “the reduction in occurrence of tumor in the Sabine et al was caused by lower weight gain and ectoparasite infestation rather by food or bedding.
I personally felt cedar shavings should be avoided unless your bunny had a mites infestation problem. They seems to be good in handling mites problem in bunnies. As a happy user of pine shavings, I would recommend wood shavings but avoid cheap & dusty shavings from China. Always check it with your nose. If the odour is strong, put it back to the shelf. So far the acceptable shaving that still in the market is Vitakraft and Percell pine shavings. Ammonia odour control is good but liquid absorption is average. Aspen shaving is also excellent choice of bedding with good odour control.
b) Wood Pellets
Woody pellet is a viable option if you find absorption of liquid is bad in wood shavings. One of the better brands is Pee Wee. China woody pellets such as Tom & Plus may be in larger bags but gassing may be a bit of a concern. Liquid and ammonia absorption is the best amongst all the beddings. The other setback is the tendency to break down into wood dust. Then, it is a good time to clean up the cage.
c) Paper shavings
Paper shavings becomes popular in Singapore in recent years. Biodegradable, no marking and good absorption. There are many brands in the market. Popular ones are BC Cat Litter, B2N bedding due to its big bag size. Some may like white bedding or with colour such as Healthy Pet or Carefresh. The only setbacks are the possibility of flies and limited ammonia absorption. However I find the odour control is better in CellSorb Bedding and Living World.
Newspaper waste is also another popular choice of bedding. Cheap and in large quantity. However, ammonia absorption is very limited and liquid absorption is also quite bad. Upper Respiratory Infection (URI) is quite common in rabbit homes filled with newspaper as bedding. Fly strike may occur in some cases of unhygienic rabbits.
e) Fleece or Cloths
The worst form of bedding is fleece or cloths. Liquid absorption is supposedly good but ammonia absorption is bad. Daily twice fleece changing is also recommended. Cheap bedding but water usage is the highest and high initial investment. Rabbit with fleece of cloths as bedding have the highest URI occurrence.
Rabbits with nothing as bedding will be infected with URI in the first month. Acid burns to the body and Fly strike are also common sightings. Having something as bedding. Something is better than nothing.
Do try them out yourself and let me know your opinion. Bunnies have a higher chance of being overwhelmed by the ammonia around the cage than by the bedding itself. Use appropriate bedding for its absorption for the betterment of your rabbit lives.