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Why do goat birth defects happen?
The goat fetus goes through known developmental stages within the womb. If all goes well, the outcome is a healthy baby goat. Unexpected outcomes range from unusual to unsustainable deformities in rare cases of goat birth defects.
When a three-legged calf was born on their ranch, Shelby Hendershot became fascinated by the odd and unusual. She created a Facebook group called “Livestock Born Different” as a place for people to share their animals and to acquire specimens to photograph, preserve, and feature in a future book. She doesn’t diagnose causes within the group, though people with similar experiences share their knowledge. She is not alone in her interest; a branch of science called teratology studies developmental abnormalities.
Not all birth defects are genetic. Teratology focuses on teratogens, which disrupt pregnancy or fetal development. There are four categories: physical agents, metabolic conditions, infections, and chemicals. Radiation from x-rays or elevated temperatures from an environment or illness are examples of physical agents. Metabolic conditions relate to nutrition and can be as simple as a deficiency or as complex as a disorder. Infections from some bacteria and viruses are known to impact gestation. Chemicals from medication or plants can also have adverse effects. In many cases, the effect dependents on timing and point of development.
In 2017, a one-eyed goat born in India captured the world’s attention. The condition is called cyclopia and results when the brain’s hemispheres do not divide, nor do the eye sockets. In most cases, the condition is rare, but in the 1950s some ranchers in southern Idaho had as many as 25% of their lamb crops with facial deformities. The Poisonous Plant Research Laboratory in Logan, Utah, determined that a plant growing in their environment, Veratrum californicum, California False Hellebore, was the cause. The specific chemical was not isolated until 1968 and appropriately named Cyclopamine.
Cleft palate (palatoschisis) and other skeletal malformations of the spine, limbs, and ribcage can be genetic in goats and environmental. Conium maculatum (poison hemlock), Lupinus formosus (lunara lupine), and Nicotiana glauca (tree tobacco), all alkaloid plants, induced defects when consumed between 30-60 days gestation (Panter, Keeler, Bunch and Callan, 1990.) In a cleft palate, the roof of the mouth fails to fuse, leaving an opening. In some cases, the lip is also affected. Kids born with a cleft palate may have difficulty nursing and risk aspiration (breathing milk), resulting in pneumonia.
Other facial deformities, often due to inbreeding, are parrot mouth and monkey mouth — overbite and underbite, respectively. While animals with this deformity are generally only mildly affected, it is not recommended to use them in future breeding.
Achondroplasia — or dwarfism — can result in short limbs, but in some cases, it results in abnormal spine growth. It is caused by a genetic mutation, though only one in five human cases is inherited. It is autosomal recessive, which means two copies of the mutated allele are needed. The risk of autosomal recessive traits being expressed increases with inbreeding.
Nicole Kiefer of Sunset Goat Ranch, in central Texas, has raised Boer and Boer cross goats for 14 years as a hobby. She purchased a group of does from a local auction and had a buck from a neighbor. She had a farm-sitter who didn’t close a gate, and the bucklings covered their dams and siblings. As a result, some of the offspring were closely inbred. A set of twins was born: one normal, the second without a neck, no tail, closed ears, and his rectum almost on top of his back. “He was adorable. We named him Quasimodo. He looked like a little white buffalo when he ran. He was so fast; we couldn’t catch him.” Then a second set of twins were born, both without necks. In cattle, the young are called “bulldog calves,” also called “short spine syndrome.” Nicole had never seen it or heard of it in goats. She shared pictures on the “Livestock Born Different” page and found she wasn’t alone.
Quasimodo required no assistance, but the second twins couldn’t stand for a few weeks, and Nicole raised them on the bottle. They were accepted and jumped and played like other goats when they returned to the herd. One of the twins only lived six months, and the other passed at one year, the cause unrelated to his birth defect.
Interestingly, a fetus’s brain forms simultaneously as the skin and hair. Abnormal scalp and hair patterns with absent or aberrant whorls may be seen on the heads of children with abnormal brain development (Wade and Sinclair, 2002.) A long-standing practice of predicting temperament by the pattern and position of a whorl on horses and cattle has a basis in brain science. While we don’t tend to examine the whorls on a goat’s face with much interest, this year, one of our kids presented with a fascinating pattern. Angelika is a Saanen cross with a facial rosette that is impossible to miss. She has other abnormalities but has never required special care apart from the herd.
Other “skin disorders” are gastroschisis and omphalocele: where the abdominal wall or umbilicus do not close, due to genetic defects or teratogen. The kid is born with internal organs outside of the body cavity in these cases. In other cases, such as “atresia ani” (imperforate anus), the cavity fails to open, and the kid cannot void waste. Surgical correction is possible, but the survival rate is not high, as these defects generally co-occur with other disorders.
Sometimes the deformities are so great that the fetus is not viable; the doe reabsorbs it, or the fetus dies before birth. This can result in abortion, but they can be carried to term with developing fetuses. If the kid is born at term, developed but nonviable, it is stillborn. If a kid is born at term, at an arrested state of development and decayed, it is a preterm death. The does body isolates the kid and protects itself and the other kids from infection through mummification of the undeveloped kid. Mummification generally presents discoloration and sunken eyes. It is best to handle aborted, stillborn, and mummified kids as an infectious biohazard. The only way to know what caused the kid to stop developing is to have a necropsy performed. While many disease processes can cause preterm death, disease is unlikely to affect only one fetus. The most common causes are: poor fetal attachment to the placenta, a congenital defect that prevents the kid from being viable, inadequate nutrition to support the developing fetuses, or maternal/fetal injury such as a blow to the side. We have seen two mummified kids in the hundreds of kids born on the ranch — one in a set of quintuplets and one in a set of triplets. The surviving kids were completely unaffected, as were the does.
Some defects are cute, and the others catastrophic. Breeders can lessen the risk of deformities by pairing unrelated animals to prevent the genetic risk of inbreeding and monitor their goats’ environments to reduce teratogens. However, random mutations can and do occur even in the best-managed herds. When a baby goat presents with a birth defect, the breeder faces difficult decisions. Will the goat enjoy the quality of life? Can the breeder provide any needed supports or interventions? If the animal can survive and thrive, it can enjoy life but should be removed from breeding herds. The breeder should be prepared to execute humane euthanasia if the animal suffers.
It can weigh heavily thinking of all of the things that can go wrong, but more often than not, everything goes right.
This article appeared in the March/April 2022 Goat Journal and is vetted for accuracy.