What is Rodent? 

Rodents make up the largest group of mammals with 2,277 species, which account for 41% of the known mammals in the world. They are a very diverse group in both size and habitat, weighing up to 66kg, with female adults that weigh less than 4gm.

Types of Rodents

Rodents are found on every continent except Antarctica. They live in a wide range of different habitats from snow-covered tundra to hot deserts. Some species of rodent are also the common invaders of the human environment:

1.       Rats

2.       Mice

3.       Voles

4.       Squirrels

5.       Marmots

6.       Hamsters

7.       Guinea pigs

8.       Gophers

9.       Prairie dogs

10.    Porcupines

11.    Beavers

12.    Capybaras (but not rabbits, hares and shrews).

However in the Philippines, the more commonly found rodent that are detrimental to humans are either the Black Rat or Brown Rat. 

Rodents tend to be social animals, living in small to very large colonies. They also have the ability to breed rapidly in favorable conditions, which is why they are such a concern when you have an infestation in your home or businesses.

Rodent Damage

 One of the main problems with a rodent infestation is the damages they cause. Rodent’s are known for being curious creatures and will often explore new areas in the search of food.

 Rodents cause immense economic losses worldwide by: 

1. Consuming, damaging and contaminating food in the field, in storage throughout the food chain and in the home. 

2. Damaging structures, buildings, bridges, sewers, and cabling etc, by gnawing and burrowing. 

3. Damaging and contaminating goods such as packaging, clothing, and furniture

 General characteristic of rat

The laboratory rat, Rattus norvegicus, belongs to the order Rodentia and family Muridae. Rats were first used for experimental purposes in the mid 1800s. Strains were developed to study neuroanatomy, nutrition, endocrinology, genetics and behavior.

1.The rat has short hair, a long naked tail, rounded erect ears, protruding eyes, a pointed snout with long whisker (vibrissae) and five toes on each foot. Albino rats have poor eyesight and depend on facial vibrissae and olfaction for sensory input. Rats have no gall bladder. Rattus norvegicus (brown rat) has a short tail compared to Rattus rattus (black rat), which has a much longer tail.

2.      Rats have a pair of incisors and three pairs upper and lower of molars. Molars are permanently rooted while the incisors have an open root and grow continuously. Due to this continuous growth of the incisors rats can have problems with incisor overgrowth when the upper and lower incisors do not meet properly (malocclusion). Malocclusion can be hereditary or follow trauma, disease or inappropriate diet and/or soft food. There is no permanent cure for overgrown teeth. The only treatment is to trim the teeth every 2-3 weeks, if malocclusion persists.

3.      Rats have a large horseshoe-shaped Harderian gland deep within the orbit. Secretions from the gland contain varying amount a reddish-brown porphyrin pigment depending on the physiologic state, age, strain and sex of the rat. The amount of secretions increases during stress and appears as 'red crusts' around the eyes and nostrils.

Normative values for rats
Lifespan	2.5-3.5 years
Adult weight	Males 300-500g, Females 250-300g
Birth weight	5-6g
Heart rate	330-480 beats per minute
Respiratory rate	85 breaths per minute
Body temperature	35.9-37.5ºC
Blood volume	50-70 ml/kg
Urine volume	3.3 ml/100g bwt/day
Allergens	Dander, urinary protein

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Reproduction of rat

rats have a four to five-day estrous cycle, divided into characteristic phases: proestrus, estrus, metestrus and diestrus. The stage of the estrous cycle can be determined by vaginal cytology. Ovulation occurs at the end of metestrus. Receptive females exhibit lordosis when a downward pressure is applied to the pelvis.

                                           Pregnancy
Pregnancy lasts 21-23 days. Females will build a nest prior to parturition if opportunity is provided. Birth usually occurs at night with 10-12 pups being born. Stretching and hindleg extension are usually signs of impeding birth. Babies are born either head or tail first (breech). The female usually eats the placenta. Delivery lasts 1-4 hours, if labor persists call a veterinarian (5-3713). There is a fertile postpartum estrus. Maternal antibody is transferred to the fetus in utero and to the newborn via colostrum.

 

Habitat of rodent

The habitats of rodents are varied and numerous, from arid (extremely dry) deserts to the arctic tundra.

1. There are rodents that live predominantly underground.

2. Some live on land,.

3. Some are primarily arboreal (living in trees).

4.  Some species spend most of their life in the water.

5. While others live in the desert.

6. Some live close to humans in urban areas and even houses, eg abandon building

7. While others make their home deep inside wetlands and rainforests.

Rodents can be found in almost every habitat and on every continent except Antarctica.