Birth abnormalities

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Occasionally nature works in ways that cause disruption of the normal development of an embryo/fetus. In these cases the result can be mild or horrific.
Birth defects are any structural or physiological abnormality that develops either before birth or during birth and is present at the time of birth.
Birth defects, also called congenital anomalies, are typically the result of faulty development, infection, environmental factors, heredity, or injury.
A genetic disease is one caused by a mutation of the genetic coding. It can be either acquired or inherited.
Often genetic issues are inherited in a Mendelian fashion, although some are the result of spontaneous mutation in the genetic code of an individual and are not inherited.
To identify and track genetic disease it is important to familiarize yourself with the issues and/or diseases themselves and the genetics involved.
Certain disease processes are directly tied to genetic inherited mutation, some are tied in with genetic predisposition or genetic factor, and others are not inherited at all.
By scientifically identifying the cause and nature of these issues with the help of your pathologist and/or veterinarian, you can get a better idea of whether or not the issues you are seeing are idiopathic, environmental, or hereditary.
A high incidence of tumors, disease, or birth defects in a line would give one incentive to discontinue or limit the line. The appearance of isolated incidents may, or may not, be reason to stop a line. Consulting veterinarians, testing, and researching are important factors in the decision-making process for the breeder.

Anencephaly


Anencephaly is congenital neural tube birth disorder (NTD) that causes the absence of a major portion of the brain, skull, and scalp.

Clinical signs

A pup born with anencephaly has a very distinctive appearance. At first glance you will notice that a portion of the skull and scalp is missing exposing an underdeveloped/incomplete brain.
Anencephalic babies are usually stillborn, although some may survive for a short time after birth.
Signs of anencephaly include the following:

• Absence of a portion of the skull (calvarium), the membranous layers of connective tissue that envelop the brain and spinal cord (meninges), and scalp.
  
  
• Brain exposure with only a partial covering of membrane.
  
  
• Brain is poorly developed and not functional (rudimentary).
  
  
• Both cerebral hemispheres may be missing.
  
  
• Cerebellum is absent.
  
  
• The cranial defect may descend to the cervical area exposing the spinal cord (craniorachischisis).
  
  
• May see protrusion of the eyes or other anomalies.
  
  

Etiology

Anencephaly is a neural tube defect (a disorder involving incomplete development of the brain, spinal cord, and/or their protective coverings) seen in rats as well as other species. In rats this affliction seems to be very rare.
During embryonic development the neural tube develops and closes to form the brain as well as the spinal cord. Anencephaly occurs when the anterior end of the neural tube does not close. This results in the absence of a portion of the brain, the skull, and the scalp. Anencephaly occurs when the cephalic (closer to the head) end of the neural tube fails to close. Often the cause of the defect can not be determined. It can be, although isn’t necessarily, an issue of heredity.
Studies have indicated that the following causes may be contributory factors in the development of anencephaly:

• Genetic: it is possible for this condition to have hereditary factors
  
  
• Nutritional: an absence of folic acid or the inability to store or process folic acid
  
  
• Environmental: toxins, maternal infections, antimicrobial treatment, or hypothermia during pregnancy
  
  

Diagnostics

Anencephaly is usually diagnosed visually after birth as mentioned above in the “Clinical Signs” section of this article. Further issues can be addressed via necropsy.
Pathology

• Underdeveloped (hypoplastic) pituitary gland
  
  
• Brain stem residue usually present
  
  

Treatment

There is no treatment for anencephaly. In most cases, babies will either be stillborn or die shortly after birth. Humane euthanasia, if the pup is born alive, may be the only option. Your vet can help you decide the proper course of action.

Outcome

At this time there is no documentation of rat babies born with anencephaly surviving.

Prevention

In order to help prevent this condition from showing up in a litter, breeders need to be aware of any predisposing genetic traits in their colonies.

Folic Acid/Folate

Folic acid, also known as folate or folacin, is a B-complex vitamin that is needed for correct neural tube development.

Folate refers to the form of this vitamin found naturally occurring in foods. Folic acid is the synthetic form of the B vitamin.

Folic acid in the diet of breeding females may lessen or alleviate incidents of neural tube development disorders such as anencephaly, spina-bifida. Because NTDs (neural tube disorders) happen very early in embryonic development it is suggested to supplement the mother with foods rich in folic acid before breeding her as well as throughout the pregnancy.

Folate can be found naturally in the following foods:

• Dried beans
  
  
• Legumes
  
  
• Lentils
  
  
• Peanuts & sunflower seeds
  
  
• Leafy greens (romaine lettuce, spinach)
  
  
• Broccoli
  
  
• Oranges, strawberries, melon
  
  
• Chicken liver (very high in folic acid)
  
  

Folic acid is the synthetic form of folate and is actually absorbed by the body better. You will find folic acid in fortified foods or vitamin supplements as opposed to natural foods.
Sources of supplemental folic acid:

• Fortified cereals (Total, Product 19)
  
  
• Whole wheat products
  
  
• Pasta (fortified)
  
  

Birth trauma


Birth is a normal biological process. It does not require management as a disease, but even a seemingly “uneventful” birth is stressful and traumatic for the mother and neonates.
Occasionally during the birth process, the pup may suffer a physical injury. This is called birth trauma or birth injury. It includes any injury affecting the infant during labor and/or delivery.
Fortunately, studies have shown that neonates recover from injury faster than adult rats.

*Note: Prior to labor, the history of trauma to the mother is of importance as this can affect the unborn babies.

During physical examination of a pregnant rat it is important not to press hard on the abdominal area. This can cause injury to the fetuses resulting in a birth defect, injuries in utero, and even death.

Causes and Effects of Birth Injuries

Normal Birth & Injury

Normal birth processes such as muscle contractions during labor, passing down the uterine horn, moving through the cervix and birth canal, and exiting through the vaginal opening can cause injuries. These birth injuries are often minor event that heal quickly, although when severe they can result in permanent damage and even death.

Size of Pup

A larger pup may have a hard time passing through the birth canal or may get “hung up” passing from a uterine horn to the birth canal. A small pup may get wedged in between larger babies. Its body may be slightly more fragile and prone to injury and bruising.

Oxygen Restriction

Birth trauma can occur when the flow of blood (and thus oxygen) is restricted during birth. This can occur from events such as (but not limited to) compression, blockage, or umbilical cord restriction.

Obstructed Birth

During an obstructed birth the pup becomes lodged either moving into the cervix or in the birth canal. A lodged pup will sometimes naturally become dislodged and birth will continue normally and uneventfully. A severely lodged pup that cannot pass through the canal will eventually die, as will the babies behind it. a pup lodged in birth canal pulled out by its mother may suffer birth injuries. This includes: bites, contusions, bruising, missing limbs, or a severed tail (partial or complete).

Prolonged/Hard Labor

A long labor can exacerbate other issues and make birth injuries worse. It can cause the oxygen supply for the babies to be limited or even diminished.

Intense labor creates extra physical stress on the babies from repeated muscle contractions while they are already confined in a tightly restricted space.

Maternal Wounding

During a difficult birth the mother may assist in the birth by pulling at the pup with her teeth. This may occur particularly if the pup is stuck. Unfortunately this can cause bite wounds and even amputation of limbs or tails.

Mothers may also accidentally wound offspring during initial cleaning while they are removing, and ingesting, the birth sac and placenta.

Compression Injuries

Compression injuries can occur either during delivery or labor and can range from minimal to severe. They are a result of external pressure.

Severe Birth Trauma

At times birth injuries can be very serious. Bones can be fractured, limbs can be dislocated, or internal bleeding may occur. Development of the neonate can be impaired from lack of oxygen.

The most severe birth trauma will end in death.

Treatment and Nursing care

Treatment, intervention, and nursing care of birth injuries should be determined on a case by case basis. With some injuries it is best to leave the pup alone with its mother and let her care for it.

There are other cases when veterinary treatment is essential, wound care is needed, or nutritional supplementation is required. In certain situations, where the outcome is terminal, there is suffering, or there are quality of life issues it may be more humane to euthanize the pup. Your veterinarian can help you to determine what level of treatment, if any, is appropriate for the injured pup.

Handling Neonates

The first step of any intervention is to be able to check or treat the pup without stressing the mother out. Sometimes a new mother rat will tolerate a known owner handling their babies for a short period of time. But some will not. It is better to assume that a mother rat my bite until you have established trust. And even then it is wise to be careful.

Odors are another important consideration. For the most part mothers will not abandon or harm their babies after they have been touched, but it can happen. When treating a pup try to keep any odors to a minimum or take appropriate measures to use methods to downplay the odors, (This will be addressed below in “Supplementing Safely” and “First Aid for Birth Injuries.”).

Females that are with new owners, came pregnant from a pet store, are rescues, or that have shown previous aggression may require using certain tactics to access the babies. One method is to simply lure the mother out of the cage or to another portion of the cage with food. Another method, if using a bin or aquarium, is to use cardboard to create a temporary barrier between her and her babies.

Supplementing Safely

Babies thrive better if they are left in the nest with their mother and their siblings. It may, however, be necessary to give them supplemental feedings at least once a day if they are not thriving. This is also sometimes done with extremely tiny babies (runts).

Because the mother rat uses her sense of smell to identify babies it is important to make sure, at least in the beginning, to not send a pup you have hand fed back to the nest reeking of formula. Not only is it a matter of her identifying the pup as something not from her nest, she may also recognize it as food and take a nip before she realizes her mistake. Usually they will simply lick the formula off the pup, but accidents do happen so it is better to be safe than sorry.

After a supplemental feeding wipe the pup down. Also, make a small dish of formula and give it to the mother before returning the pup to the nest. It will help her to trust you and also mask any formula smell on the pup.

First Aid for Birth Injuries

Generally the only first aid for babies will be wound care. Use a sterile saline solution on open wounds to clean them. Pat the areas dry an apply a small amount of antibiotic ointment once or twice a day as recommended by your veterinarian.

You can dab some ointment on mom’s nose, the top of her front paws, or on her chin. This may fool her into thinking the ointment is on her rather than on the pup, which may help keep her from licking it off the wounds.

Medication

It is not often that birth injuries will require medication such as antibiotics. If the vet deems that medication is appropriate, be sure it is not one that may cause the pup more harm than good.

Neural tube defects

Definition

Neural Tube Defects (NTD) are the result of the neural tube failing to form or close properly during embryonic development.

Clinical signs

The individual neural tube defects each have their own unique signs and etiology.

Etiology

The brain and spinal cord begin development as a groove that folds over laterally to become a tube (the neural tube). Layers of tissue that come from this tube normally cover the brain and spinal cord (meninges).
Fusion of the neural tube begins cranially (towards the head) and progresses caudally (towards the tail). The anterior and posterior ends of the neural tube remain open for a period of time during neural tube development, but eventually close.

In NTDs the neural tube does not develop normally, which may affect the brain, spinal cord, and meninges.

Some Examples of Neural Tube Disorders

• Anencephaly-
  
  
  
  • Anencephaly is the most severe form of neural tube defect, the brain tissue as well as a portion of the spinal cord are absent. This defect is fatal.
    
  
  
  

• Spina Bifida-
  
  
  
  • The term spina bifida covers a range of vertebral and neural tube defects.
    Spina bifida results when the neural tube fails to close completely and remains an open channel. It is the failure of the posterior vertebral arch to fuse.
    
  
  
  

• Exencephaly-
  
  
  
  • A condition in which the skull has not developed normally, causing exposure or extrusion of the brain.
    
  
  
  

• Hydrocephaly-
  
  
  
  • Hydrocephally is an abnormal accumulation of cerebrospinal fluid in the ventricles of the brain resulting in elevated intracranial pressure. It is often referred to as “water on the brain.”
    
  
  
  

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