Small rodents

Ideally, when small mammals are being evaluated, the treated area beyond the test site should be large enough that any recruitment of study species to the test site will be from a treated area. It is not possible to cover this recruitment area for most bird species and it is often impractical for small rodents, but should be considered. Owing to abundance, home range and recruitment dynamics, small passerines and small rodents are often selected as test species. 

For the ecological assessment, risk analysis was based on the traditional PEC/ PNEC ratio (Hazard Quotient) where PEC is the predicted environmental concentration (resulting from chemical analysis) and PNEC the predicted no-effect concentration. Ecological assessment for aquatic species was based on rainbow trout or fathead minnow while terrestrial assessment was based on small rodents like mice rats and rabbits. Exposures associated with HQ<1 were considered negligible. 

The evaluation of risk has underlined the possible adverse effects both on human health after the exposure to drinking water contaminated by landfill leachate and on small rodents and aquatic species at the hypothesized condition for humans, the estimated toxic effects of the raw leachate are mainly due to the levels of ammonia and cadmium and carcinogenic effects are induced by arsenic first and then by PCBs and PCDD/Fs while ecological potential risk is mainly attributable to the concentration of inorganic compounds, in particular ammonia for small rodents, cadmium, ammonia, and heavy metals for fishes. 

It is a hantavirus that is normally found in the former Yugoslavia. The natural reservoirs are small rodents and the virus is shed in their urine. Infection occurs after inhalation of dust contaminated with excreta from infected rodents or from aerosol of animal blood or fluids. Does not produce disease in animals. This is a biosafety level 3 agent. 

HCN is detoxified to thiocyanate (SCN ) by the mitochondrial enzyme rhodanese rhodanese catalyzes the transfer of sulfur from thiosulfate to cyanide to yield thiocyanate, which is relatively nontoxic (Smith 1996). The rate of detoxification of HCN in humans is about 1 pg/kg/min (Schulz 1984) or 4.2 mg/h, which, the author states, is considerably slower than in small rodents. This information resulted from reports of the therapeutic use of sodium nitroprusside to control hypertension. Rhodanese is present in the liver and skeletal muscle of mammalian species as well as in the nasal epithelium. The mitochondria of the nasal and olfactory mucosa of the rat contain nearly seven times as much rhodanese as the liver (Dahl 1989). The enzyme rhodanese is present to a large excess in the human body relative to its substrates (Schulz 1984). This enzyme demonstrates zero-order kinetics, and the limiting factor in the detoxification of HCN is thiosulphate. However, other sulfur-containing substrates, such as cystine and cysteine, can also serve as sulfur donors. Other enzymes, such as 3-mercapto-pyruvate sulfur transferase, can convert... 

Among the requirements for registration of pesticides in the United States, the 1978 guidelines proposed by the U.S. Environmental Protection Agency (3) list general metabolism studies "in at least one mammalian species, preferably the laboratory rat. .." Although similar tests have been conducted on other terrestrial species with increasing frequency, the small rodents have remained the principal source of metabolism data from intact animals. 

Sontag JM, Page NP, Saffiotti U. Guidelines for Carcinogen Bioassay in Small Rodents. National Cancer Institute, NCI-CG-TR-1. DHEW Publ. No. (NIH) 76-801. Washington US GPO. 

For subcutaneous injections a large skin surface area is available for daily applications. It is recommended to change the site of injections continuously because repeated injection to the same site can cause fibrotic reactions and, in case of treatments for a period of 1 year and longer, induce subcutaneous tumors especially in small rodents. The risk of inducing local skin tumors is high if the pH value of the administration solution is below 5. 

Problems can come about if due to technical difficulties a second blood sample has to be taken within a short period after the first, failing withdrawal. In a small rodent the loss of blood is counteracted by rapid erythropoesis in the bone marrow, and the spleen. During the histopathological evaluation increased erythropoesis is seen in the bone marrow and the spleen (extra-medullary hematopoiesis). 

Urine can be collected in small rodents by the use of metabolism cages, in large non-rodents by catheterization. 

The test is conducted by using the mechanically congested A. centralis of the rabbit ear. The injection is directed into the distal direction. A 7,5 % solution of thiopental can serve as a positive control because it induces severe inflammatory reactions. The further procedure includes evaluation scores being used as for the i.v. injections. To eliminate the species-specific influence of small rodents (small artery) it is also recommended to use non-rodents like the dog. 

NAS-NRC, PRINCIPLES FOR EVALUATING CHEMICALS IN THE ENVIRONMENT, 1975 11 NCI, GUIDELINES FOR CARCINOGEN BIOASSAYS IN SMALL RODENTS... 

At the present the guidelines for long-term mammalian carcinogenesis recommend a 24-month test in small rodents (Figure 12). It is advisable to use male and female animals in each group. Controls should include (.1) normal controls for... 

There is strong evidence that sulfur compounds in urine and feces signal predator to prey species (Nolte et al. 1994). The major compounds in mustelid anal gland that repel small rodents are sulfur compounds such as sulfides, thiols, thie-tanes, or dithiolanes. These compounds have been used to deter rodent pests (e.g. Sullivan et al. 1988). 

Insects offer endless opportunities for experiments with defense secretions. For a review, see Eisner et al. 2005. Upon gentle contact with a forceps insects will release defense secretions. Keep the insect that just has released the defense secretion in a vial with a wire screen cover, or in a tiny wire cage of the type honey bee queens are shipped in through the mail. Observe responses by other insects or predators such as spiders, lizards, frogs, birds, or small rodents. 

Bury little bags with 1 g of seeds in soil of different depths. Use three treatments unscented seeds, seeds scented with safflower oil, and seeds with pine oil. Give small rodents such as mice, gerbils, or hamsters, a choice of scented and unscented batches. Is there evidence that they detect buried sees by smell Does the treatment affect the success rate in finding the hidden food At what soil depth do the animals detect the food ... 

Owls that feed in agricultural areas provide benefits to humans by killing large numbers of small rodents which... 

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