There are many undesirable traits that show up in beefcattle. These range from poor performance and structur-al unsoundness to semi-lethal and lethal diseases.Many of these are caused by varying amounts of genet-ic influence; others are caused by environmental condi-tions or an interaction between the animal's geneticmakeup and the environment in which it lives.Congenital defects are present in all breeds of cattle. Inmost herds, they are rather uncommon; however, occa-sionally the frequency within a herd will be highenough to be of considerable economic importance.Congenital defects are abnormalities of structure orfunction present at birth and may account for a highpercentage of calf losses from just before to just aftercalving. The frequency of congenital defects rangesfrom less than 1 to over 3 percent within herds. Cattlebreeders should be conscious of potential defects andinvestigate animals exhibiting unusual characteristics.

Causes

The cause of many congenital defects is unknown, butsome are inherited. The most common inheritance pat-tern is as a simple recessive trait. The defective calfreceives a recessive gene from its sire and one from itsdam. A few congenital defects are known to be causedby genes with incomplete dominance and a few arecaused by two or more sets of genes.

Genetically caused congenital defects usually run infamilies. The parents of a genetically defective calf willgenerally have at least one ancestor in common. Whenmore than one genetically caused defective calf is bornin a herd in the same calving season, their dams are

usually related (for example, half sisters) and are siredby the same bull. A change in the breeding program isrequired to correct this situation.

Many congenital defects are caused by environmen-tal factors. These include the level of nutrition, excess orshortages of certain nutrients, toxic plants or other toxicsubstances, infectious diseases, and extremes in tem-perature during pregnancy. Most environmentallycaused congenital defects will occur during a short peri-od of the calving season, from cows that were managedas a group. After proper diagnosis, a change in manage-ment is necessary to correct these conditions.

Diagnosing the Cause

To determine the cause of defects, the breeder musthave good records and know why every calf dies.Breeding records which include sire and dam of eachcalf and breeding date are needed. Blood typing or DNAtyping of the calf and possible parents can be used tohelp determine parentage. The calf must be alive and atleast one month old when the blood sample is obtainedfor blood typing. Management records should includewhich cows were in groups during each time period.Most breeders have a list of which cows are in each pas-ture. A date in and out of the pasture usually will helpidentify problems. Feed analysis reports, toxic plantspresent, and herd health and vaccination programs arealso of value.

Knowing the cause of death is important in control-ling diseases as well as congenital defects. The cause ofsome deaths will be obvious, others will be much moredifficult. If the breeder does not know the cause, they

BCH-1900 1

Congenital Defects in Cattle

R. R. Schalles, Department of Animal Sciences and Industry, Kansas State UniversityH.W. Leipold, Department of Pathology, Kansas State University

R. L. McCraw, Department of Animal Science, North Carolina State University

Beef Cattle Handbook

Product of Extension Beef Cattle Resource CommitteeBCH-1900

should get help from their local veterinarian or statediagnostic laboratory. The breed associations, AI organi-zations, and extension personnel usually can help con-tact diagnostic personnel also. It is very important to actfast. Tissue of a dead calf will deteriorate very fast inwarm weather, especially the nervous system. If the calfcannot be delivered to the laboratory within a few hoursafter death, it should be well cooled before transporta-tion. The best diagnosis can be obtained from a calfdelivered alive. Call the diagnostic laboratory ahead sothey can give instructions on how to handle the calf andbe ready when it arrives. If a defect is diagnosed asgenetically caused, the breeder of the animal and thebreed association should be notified. The responsibilityfor control of genetic defects rests primarily with thepurebred breeders and breed associations. Good diag-nosis from one dead calf may save many others.

Genetic Defects

l. Dwarfism. There are several types of dwarfismcaused by both environment and genetics. Each ofthe three genetically caused dwarfisms discussedhere are different traits caused by different sets ofgenes.

a. Snorter dwarfism causes short, blocky appearancewith deformed bone growth in the nasal passageswhich causes difficulty in breathing. Inherited as asimple recessive trait (Figure 1).

b. Long head dwarfism causes small size but does notaffect the bone growth in nasal passages. Inheritedas a simple recessive trait.

c. Compress dwarfism is inherited as incomplete dom-inance. An individual with one compress gene andone normal gene has an extremely compressedbody conformation. The individual with two com-press genes is a dwarf and the calf dies at or soonafter birth.

2. Water head (internal hydrocephalus). Excess fluid ispresent in the brain (Figure 2). Calves are usuallyborn dead or die shortly after birth. Environmentalfactors can cause the disease, as well as being

inherited as a simple recessive trait.3. Marble bone (osteopetrosis). The calves are usually

born dead two to four weeks early. Bones are solid

2 Beef Cattle Handbook

Figure 1. Dwarfism. Notice short, blocky appearance withdeformed nose causing labored breathing (snorter dwarf).

Figure 2. Waterhead (internal hydrocephalus). Calf was borndead. Notice dilation of internal aspects of cross-section of thisbrain.

Figure 3. Marble bone (osteopetrosis). This calf was aborted threeweeks before its term. Notice thick bone with no bone marrowcavity.

Figure 4. Hairlessness (hypotrichosis) in a calf.

and do not contain marrow, making them very brit-tle and easily broken (Figure 3). Inherited as a sim-ple recessive trait.

4. Hairlessness (hypotrichosis). Partial to almost com-plete lack of hair (Figure 4). Hair develops and is lostso an affected animal will vary somewhat in expres-sion from month to month. Inherited as a simplerecessive trait.

5. Rigid joints (arthrogryposis). Many environmentallycaused forms appear but one form is inherited as asimple recessive trait. The joints of all four legs arefixed symmetrically and a cleft palate is present(Figure 5).

6. Extra toes (polydactyly). One or both front feet areusually affected, but all four may have the outerdew claw develop into an extra toe (Figure 6). Atleast two sets of genes are involved in the inheri-tance of this trait.

7. Mulefoot (syndactyly). The two toes are fusedtogether to produce only one toe. The front feet aremost often affected, but all four may be affected(Figure 7). These cattle cannot tolerate hot tempera-tures. Inherited as a simple recessive trait.

8. Weaver calf (progressive bovine myeloencephalopa-thy). Calves start developing a weaving gait at 6-8months and get progressively worse until death at12-20 months (Figure 8). Inherited as a simple reces-sive trait.

9. Photosensitivity (protoporphyria). Animals are sen-sitive to sunlight and develop scabs and open soreswhen exposed to sunlight (Figure 9). The liver isalso affected and the animals may suffer fromseizures. Inherited as a simple recessive trait.

10. Bulldog (achondroplasia). This trait is inherited as anincomplete dominant. The homozygous may beaborted dead at 6-8 months gestation, and has acompressed skull, nose divided by furrows andshortened upper jaw, giving the bulldog facialappearance. The heterozygous calf is small andheavy-muscled (Figure 10).

11. Double muscling. Animals are extremely heavilymuscled (Figure 11). However, considerable varia-tion exists in the expression of this trait. Inherited asa simple recessive trait.

12. Parrot mouth (brachygnathia inferior). One type ofparrot mouth (Figure 12) is inherited as a simplerecessive trait. The more common cause of teethand denture pads not meeting is a quantitative traitcaused by several sets of genes. This can causeeither an under or over shot jaw with varyingdegrees of expression.

13. Cryptorchidism. One or both testicles fail to descendinto the scrotum. Inherited as a sex limited trait andprobably involves at least two sets of genes.

14. Prolonged gestation.The fetus fails to trigger partu-rition. Parturition must be induced or the calfremoved. The calf is often extremely large and oftendies. Inherited as a simple recessive trait.

15. White eyes (Oculocutaneous Hypopigmentation).

Hair coat is a bleached color and the iris is pale bluearound the pupil with tan periphery. Inherited as asimple recessive trait.Many other genetically caused undesirable traits are

known. The beef cattle geneticist at your land grant uni-versity will have knowledge of most of them and will beable to help if a problem arises.

Many abnormal conditions are not geneticallycaused. Two headed calves and calves with extra legsare caused by mistakes in development and not thegenetic makeup of the individual or its parents.Freemartin heifers are caused by circulation of the maletwin's hormones through the developing female fetus.Some hydrocephalus can be caused by BVD (bovinevirus diarrhea) infection during pregnancy. Crippled-calfdisease is caused by the cow eating lupines betweendays 40 and 60 of pregnancy. Flexed pasterns (contract-ed flexor tendons) is usually caused by a large fetus

developing in a small uterus. However, both crippled-calf and flexed pasterns can also be genetically caused,inherited as simple recessive traits.

Controlling Genetic Diseases

The best control of genetic diseases is to avoid animalsthat carry these genes. Bulls or semen should be pur-chased from reputable breeders, produced by parentswho are not known to carry undesirable genes. Long

BCH-1900 3

Figure 5. Rigid joints (arthrogryposis) in a calf. Notice rigid frontlegs. These calves have a cleft palate.

Figure 6. Extra toes (polydactyly).

established inbred lines that have not recently producedgenetic undesirables are usually quite safe. Commercialproducers who use a crossbreeding system rarely have aproblem.

The elite purebred breeder or owner of Al bulls maywish to test for simply inherited traits before bulls ordonor cows are heavily used. If the undesirable trait isdominant, no test is needed since the animal wouldshow the trait even if only one dominant gene is pre-sent. If the trait is inherited as incomplete dominance,the individual that has only one undesired gene canusually be identified and testing is not needed. Testing isusually useful only when the trait is inherited as a sim-ple recessive trait.

When only one nonlethal, undesired, recessive traitis of concern, the least expensive test is to mate the ani-mals to ones having that undesired trait. For example, if

horns are not desired, the polled animal to be testedwould be mated to horned animals to produce at least 7calves (P>.99). If any horned calves are produced, thepolled animal has one gene for horns.

If the undesired trait is lethal, the dead animals can-

not be used to make the test. If only one lethal trait is ofconcern, the test should be made using animals thathave produced calves with this lethal trait. At least 16calves should be produced from these matings (P>.99).If a calf is produced that has this lethal trait, the testedanimal has one recessive gene for the trait.

If the breeder is concerned about identifying allrecessive traits, at least 36 progeny from sire-daughteror mother-son matings should be produced (P>.99). Thistest is time consuming and expensive and only trulyoutstanding animals will be able to pay for it. All calvesfrom these matings must be observed very closely andall recessive traits recorded. The tested animal will havea recessive gene for any recessive traits observed.

What to Do with Carriers

An animal that has one undesirable recessive gene mayhave thousands of very desirable genes. The animal'sdesirable genes should be weighed against its undesir-able genes. If the desirable genes can be found in other

animals without the undesirable gene, carriers should beslaughtered and replaced. When the production traits aresuperior, these animals can be used in a crossbreedingprogram to produce beef. Heifers should not be kept forbreeding. If the individual is extremely superior in pro-duction traits, a superior son can be produced that doesnot carry the undesirable gene. The outstanding carrieranimal would be mated to a small group of very out-standing individuals. The best two to four sons producedwould be selected and used in test matings to knowncarrier cows. The best son that does not carry the unde-sired gene would then be used and all carriers slaugh-tered. This would take several years and only trulysuperior individuals could justify such a procedure.

In most cases, the animal that carries the undesirablerecessive gene should not be used to produce breedinganimals. Daughters should be worked out of the herd andreplaced with superior animals that do not carry undesir-able genes. Purebred breeders should work with their

4 Beef Cattle Handbook

Figure 7. Mulefoot (syndactyly). Notice single toe as compared tothe normal front foot.

Figure 8. Weaver calf (progressive bovine myeloencephalopathy)/Notice unsteady posyure of this animal.

Figure 9. Photosensitivity (protoporphyria). Notice skin lesionsdue to sunlight.

breed associations, extension and university personnel,and veterinarian to eliminate and avoid problems.

Ethical and Legal Considerations

Serious ethical and legal problems are involved in sellingknown carrier cattle or progeny of known carriers. Aseedstock producer in this position should be completelyhonest with the buyer. It is doubtful that he should sellpossible carriers, under any circumstances, to a young-ster or to someone who is just getting started in busi-ness and may not have the knowledge to understand theconsequences of using offspring from known carriers.Selling carriers without informing the buyer will ulti-mately reduce the confidence that buyers have in thebreeder and may eventually reflect negatively on theentire breed.

BCH-1900 5

Figure 10. Bulldog calf (achondrodysplasia).

Figure 11. Double muscled calf on pasture. Notice outline of hindlegs and deep creases between muscles.

Figure 12. Parrot mouth (brachygnathia inferior). Short lower jawin a calf.

Authors:R. R. Schalles, Department of Animal Sciences and Industry, Kansas State UniversityH.W. Leipold, Department of Pathology, Kansas State UniversityR. L. McCraw, Department of Animal Science, North Carolina State University

This publication was prepared in cooperation with the Extension Beef Cattle Resource Committee and its member states and produced inan electronic format by the University of Wisconsin-Extension, Cooperative Extension. Issued in furtherance of Cooperative Extensionwork, ACTS of May 8 and June 30, 1914.

BCH-1900 Congenital Defects in Cattle