CAE, Caprine arthritis-encephalitis, and what it can mean to your ranch!

CAE, Caprine arthritis-encephalitis, and what it can mean to your ranch!

By Gail Bowman

My husband, David, and I started raising Boer goats in 1994 when we saw an advertisement for Boer meat goats in a magazine. We had bought two dairy goats the year before, fallen totally in love with them. We wanted more goats, but not more milk. So we mortgaged our house and flew to California to bring home our first pair of Boer goat kids. What an awful experience! They were both sick! They had staph infections, lice, chlamydia, and the little girl was pregnant at four months old! Argh! Well, we were in an instant legal battle which taught us a lot about goat diseases and the value of knowing your breeder! After that, we found a good veterinarian to teach us how to test our own goats, and what to test for. Our ranch is now CAE, CL and Johne's negative, and has been for over three years. We test for disease twice a year, and are very serious about the results.

When I tried to find a dairy ranch in my area that tested for any diseases, especially CAE since I live in a high incidence CAE area, I met with surprising resistance and even anger from the local dairy goat raisers. I had people tell me that, "CAE is impossible to get rid of, so why make waves?", and "CAE is just a phantom disease with no real evidence that it exists." I even had hate mail and nasty phone calls! Well, wouldn't you know that that kind of resistance just made me more determined? I finally did find a ranch that had been testing for CAE for 3 years, and I bought my dairy base for cross breeding from them.

Now, four kidding seasons after that first experience, we have met and visited many of the top breeders in the United States and Canada. I am the coordinator for the International Boer Goat Association for the Northwestern United States. We have done extensive research on, and have a good understanding of, Boer blood lines and breeding practices. We are very excited about our crop of beautiful kids this year! Our kids have the advantage of a carefully designed feeding program, a disease free environment, and the best spectrum of genetics available! I guess that just goes to show that good can come from the most unfortunate of circumstances!

Please allow me to share with you some of the new research I have discovered on CAE. It is not a phantom disease! It is easily understood and makes perfect sense. Why would any breeder want to ignore a disease that will cut down on their production and can be easily controlled? Now, I know that is not reasonable if you have 2000 meat goats. Who has time to worm much less test? But most of us have relatively small breeding operations, or dairy operations, that would benefit by the control of this disease.

CAE or CAEV (Caprine arthritis-encephalitis virus) is a common disease of goats that is prevalent worldwide. In the United States, prevalence as high as 81% has been reported for goat herds. According to a recent study by J. D. Rowe, DVM, "Infection most commonly occurs when the virus is present in colostrum or milk that is ingested. However, prolonged contact, particularly in high-density goat populations, also results in significant transmission." (5 p. 35) Not all CAEV infections in kids can be explained by ingestion of affected colostrum or milk. Up to 10% of kids from positive dams, who were removed from their mothers at birth, have been reported to show infection. In these cases, infection must have occurred in one of four ways: 1. in-utero transmission, 2. transmission from the dam by vaginal contact, 3. accidental ingestion of infected colostrum, 4. transmission from the dam by exposure to saliva or respiratory secretions during licking.

CAEV infection may not be serologically testable for months or years, and some infected animals, who can transmit the disease, may never show clinical symptoms. Symptoms include a progressive rear leg weakness and/or paralysis in kids 2 to 6 months of age, chronic arthritis (most frequently, but not solely, of the knee joint) in adults, inflammation of the mammary gland, lung, and nervous system. Nervous system involvement may include blindness, head tilts, and facial nerve paresis. Mammary involvement results in "udder edema" or "hard udder" where the entire udder becomes hard and warm within the first few hours after kidding, resulting in the kids going hungry. (11) (This is not to be confused with the doe that has so much milk at kidding that she needs to be milked in addition to nursing her kids.) Lung involvement results in chronic pneumonia.

In a milking herd, shared milking machines, milk contaminated hands or towels, etc. will significantly increase the risk of spreading the disease. In a meat herd, transmission can occur via needles, tattooing instruments or dehorning equipment. Also cited by P. L. Greenwood as possible avenues of infection, in high density herds that are endemically infected, are head butting to the point of drawing blood, eye-licking, biting, snorting and coughing, and urinating too near another goat's face.(15) In addition, according to Rowe and East, sexual contact has been researched with some definite indications that the risk of infection in the exchange of saliva, estrus mucus, urine, semen and nasal secretions, is possible. (5 p. 41)

The period of time between exposure to CAEV and development of detectable (testable) antibody levels has been estimated, by researchers, at between 3 weeks to 8 months after exposure to the disease.(16)(17)(18) Many ranches have reported conversion from negative test results to positive test results of goats as old as five years of age, although conversion seems to be most prevalent between 1 and 2 years of age. Researchers attribute conversions later than two years of age to some lateral exposure to the disease as discussed in the last paragraph.

The following steps are recommended to prevent CAEV transmission: 1. Immediately remove the kids from their dams at birth (with the sack intact until the kid is out of its mother's body, if possible), being careful to prevent the does from licking their kids. Then take the kid inside and wash it in warm water, in a clean sink. 2. Provide heat treated, artificial or cow colostrum. Do not pool colostrum from mothers that might be infected and then feed the pooled colostrum to your isolated kids! 3. Feed pasteurized or powdered milk. 4. Separate all possibly infected animals from uninfected animals by a double fence with at least 10 feet between the fences. Do not use common feeders, waterers or salt blocks. 5. Milk negative and younger does before milking positive and older does. 6. When possible, breed negative does with negative bucks. If negative and positive animals are mated, use a single hand-mating allowing minimal oral contact. 7. Do not share needles, tattooing equipment or dehorning devices without careful cleaning and sterilization. 8. Test your kids at 6 month intervals starting after the kids are at least 4 months old. Most breeders suggest testing during times of stress, such as about 2 to 3 weeks before kidding. There is, however, some evidence to suggest that a goat with another type of systemic infection may test with a false positive for CAEV.(5)

You can easily and inexpensively draw your own blood samples for disease testing. Just use a 3cc syringe and an empty, sterile, red top blood vial. Get someone to show you how to get the blood, put it in the vial and Next Day it to a good lab. Here are a few laboratories that may be able to process your blood sample. If there is not one listed in your area, try calling the one that is nearest you. They probably know of another lab that is closer.

California Veterinary Diagnostic Lab System

West Health Sciences Drive

University of California - Davis

Davis, Calif. 95616

(916)752-7577

National Animal Disease Center

PO Box 70

Ames, Iowa 50010

Pan American Veterinary Laboratories

3921 Steck Ave

Austin, Texas 78759

(512)794-9657 Fax

(800)856-9655

Veterinary Diagnostic Laboratories

University of Minnesota

College of Veterinary Medicine

Carter and Gortner Aves.

St Paul, Minnesota 55108

Washington Animal Disease Diagnostic Laboratory

College of Veterinary Medicine

Washington State University

PO Box 2037

College Station/Bustad Hall, Rm 155-N

Pullman, Washington 99165-2037

(509)335-7424 Fax

(509)335-9696

Diagnostic Laboratory

Cornell University

College of Veterinary Medicine

Ithaca, New York 14853

Footnotes:

(5)Rowe, Joan Dean, and Nancy E. East."Risk Factors for Transmission and Methods for Control of Caprine Arthritis-Encephalitis Virus Infection" The Veterinary Clinics of North America Mar 1997 Vol 13 #1

(11)East, Nancy E. "Diseases of the Udder" The Veterinary Clinics of North America Nov 1983 Vol 5 Num 3 p.591-600

(15)Greenwood P.L., R.N. North, and P.D. Kirkland."Prevalence, spread and control of Caprine Arthritis-Encephalitis Virus in dairy goats in herds in New South Wales" Aust Vet J 72:341, 1995

(16)Oliver, R.E, R.A. McNiven, and A.F. Julian, et al."Experimental infection of sheep and goats with Caprine Arthritis-Encephalitis Virus" NZ Vet 30:158, 1982

(17)Ellis T.M., H. Carman and W.F. Robinson, et al."The effect of colostrun-derived antibody on neo-natal transmission of Caprine Arthritis-Encephalitis Virus infection" Aust Vet J 63:242, 1986

(18)Rimstad E., N. East, and E. DeRock, et al."Detection of antibody to Caprine Arthritis-Encephalitis Virus using recombinant gag proteins" Arch Virol 134:345, 1994

Gail Bowman is the author of the book Raising Meat Goats For Profit and parts of this article are excerpts from that book.

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