In this complete guide to CAE in goats, we answer the most common questions that farmers ask about caprine arthritis encephalitis, including what its, symptoms, how it’s transmitted, and treatments.
What is CAE in Goats?
CAE or Caprine Arthritis Encephalitis is now one of the most significant diseases that affect goat industry especially in the US. The CAE in goats also known as “big-knee disease.”
CAE caused by a virus known as lentivirus, which is responsible for many other immunity suppression diseases in many species, and most goat breeds are susceptible.
CAE cause several diseases in goats like arthritis, mastitis, pneumonia, loss of weight in adults, and encephalitis (swelling of the brain and brain stem) in the young ones.
The incubation period (the time elapsed between the exposure to a pathogenic organism and when the signs are first apparent) of the disease is highly variable. Most of the goats become infected when they are very young and develop disease months or a year later.
CAE in Goats - Symptoms
Two different forms caused by the CAE virus, a neurological disease that affects brain and the spinal cord of young goats and joint type of adult goats result in arthritis. The clinical symptoms of the two types are:
Nervous/Encephalitis Form of CAE
The encephalitis form of the CAE virus is most often occurs in the young goats of 2-4 months of age. The disease is characterized by paralysis that may or may not progress to seizures or death.
All the breedS of the goats are sensitive to the CAE virus, and both sexes can get this infection. There will be development of weakness (paresis) in the hind limbs that may lead to paralysis. The early paresis may be considered as lameness, in-coordination or weakness of one or both hind legs.
The common signs and symptoms of CAE virus include head pressing when the animal stands against a hard object. Knuckling over the feed and difficulty in getting up may follow until such time that the animal is no more capable to get up.
The course of the disease is from more than a few days to several weeks. The young ones will remain active and alert and keep eating and drinking even after infected with the virus. There might be mild pneumonia in the young ones. These signs develop due to the swelling of the spinal cord caused by the virus.
Arthritic Form of CAE
This form of the CAE virus appears in the goats of that are1-2 years old. There is inconsistency in the progression of the disease symptoms. Some goats may only show mild symptoms like difficult walking or stiffness for years while other goats may get a severe infection.
The lameness in goats will then lead to swelling of the front knees and can also appear in other joints of the hind limb. As the disease advances, there will be joint pain, and stiffness of muscles becomes more prominent. The goat will start lying on the ground, there will be reduction in the weight and development of a rough coat occurs. The goat will then refuse to rise.
How is CAE Transmitted in Goats?
The virus if CAE transmitted naturally during the early phase of goats, i.e. from infected adult mother to the offspring via consumption of the colostrums (first milk) and milk. There is the possibility of transmission of this virus from pregnant female goat to the fetus.
There are several shreds of evidence that CAE virus also transmitted directly from goat to goat, possibly through the nasal discharge and saliva. Other routes of transmission of CAE virus include through the urine, semen, faeces, milking machine, and failure to utilize clean instruments on each animal for vaccination, drenching, tattooing etc.
How to Test for CAE in Goats
A presumptive diagnosis is usually made on the clinical signs and history, taking into consideration the age of the animal and disease pattern. However, there are several diagnostic tests available for CAE virus detection.
These methods can be categorized as the either serological or molecular procedure. The agar gel immune-diffusion test and ELISA (enzyme-linked immune-sorbent assay) testing are two types of serological testing. In contrast, molecular assay includes PCR (polymerase chain reaction) method for the diagnosis of CAE virus.
The Western Blot is a lesser-used test for the screening but is seen as a standard gold test for the diagnosis. Both the agar gel immune-diffusion test and ELISA are considered significantly reliable to use in the control programs. The agar gel test is more specific but less sensitive as compared to the ELISA.
CAE in Goats – Treatment
There is no particular treatment for any of the clinical signs linked with CAE viral infection. Though, supportive therapy may helpful for individual goats. The affected goats with arthritis may get better with regular foot trimming. There should be an addition of bedding for the goats with the administration of pain killer injections.
The goats suffering from CAE need management for weeks with good care. There should be the administration of antibiotics will help to avoid secondary bacterial infections that may cause pneumonia or mastitis. As long as high-quality digestible feed is accessible, the goats may delay the onset of the disease.
In commercial flocks, one of the below mentioned procedures is advisable for controlling CAE:
If the control program includes isolation of positive goats, then the group of positive goats should be placed at 6 ft distance and shared equipment should be disinfected properly to avoid the spread of the disease.
Management of CAE in Goats
As there is no precise treatment for the CAE virus, and the animal may not recover the whole life, this disease can control by following the proper management. The management includes the proper hoof trimming of the animals with mild cases of arthritic form. This trimming will help them to move comfortably to the feed and water.
Animals with more severe signs should be considered for euthanisation. As the male will keep shedding the virus and females will spread the disease to the offsprings through milk and colostrums, so serious considerations should be given to keep these infected animals.
There should be regular testing for CAE to ensure that the heard is free from this viral disease. A negative CAE herd must keep as a closed herd and only introduce new stock that has been tested negative for CAE.
The offspring should keep away from their female goats before they can stand and suckle and should get heat-treated goat colostrums and raised on pasteurized milk or milk replacer.
Kids should also be kept isolated to avoid having any contact with adult goats. Keep away from overcrowding of the animals, keep all feed and water sources clean and germ-free, and keep the site as dry as possible.
Is CAE in Goats Contagious to Humans?
There is no serologic or clinical evidence that people are susceptible to the CAE virus. Humans consuming milk from infected female goats can develop antibiotics to the CAE virus. There are no pieces of evidence that this contact resulted in a persistent viral infection in humans.
The surface glycol-protein on the CAE virus and HIV can cross-react. It is thus suggested that exposure to the CAE virus in goat milk may lead to the false-positive reaction to HIV in some people.
Can Sheep Get CAE from Goats?
The CAE virus infects goats and to a lesser extent, sheep. The frequency of cross-species transmission (transmission of disease from goat to sheep) is unknown and has rarely been demonstrated under natural conditions. However, management may play a role.