Back to Articles page

An Overview of Rabies
By Missi Cooper VMD

With the recent diagnosis of a rabid llama in York County it is important to understand this disease and how to protect your animals. Rabies is a viral neurological disease that can infect all warm-blooded animals including humans. Most often infection with rabies is fatal and unnecessary due to it being preventable. Animals that become infected show variable clinical signs that develop three weeks to three months after exposure. Some of these signs are lameness, ataxia (unsteady gait), hind limb paralysis, and changes in behavior. There are three main forms of rabies that are associated with these behavior changes, aggressive or furious rabies, depression or dumb rabies, and paralytic rabies.

Aggressive Horse
Furious rabies early clinical signs include muscle tremors, bloating, straining to pass manure, and bellowing. Theses animals also are aggressive towards other animals, people, and objects in their environment. With a slight sound or touch they can run through stall doors or fences. They soon become unable to stand and usually die in convulsions two to four days later. The positive llama had this form and some of the early signs that it had were loss of appetite, the inability to stand, facial swelling and paralysis. From the time that the loss of appetite was noted until it died was four days, and in this time it chewed out of a stall, bit several other llamas and was aggressive towards people.

Two dogs with Dumb Rabies
Dumb rabies main clinical sign is depression but other signs that can be seen with this form are loss of appetite, fever, drooped head and neck, and straining to pass manure. They tend to fall down or have difficulty standing which rapidly worsens over the next one to three days. The muscles around the opening to the trachea or windpipe and the esophagus become paralyzed resulting in noisy breathing, froth around the mouth and inability to drink. Other signs of this form are decreased tongue and anal tone, head pressing, circling, blindness, and abnormal eye movements.

Horse with paralytic rabies
Clinical signs of the third form or the paralytic form are lameness, unsteady gait, and then the inability to stand after three to five days. They are usually dead after ten days.
Regardless of the form seen the virus enters the animal through the skin from a bite or through a wound that had contact with rabid saliva. The virus then starts to multiply at this site and then after several days enters the central nervous system by traveling through the peripheral nerves, spinal rootlets, and the spinal cord. Once the virus reaches the brain it then travels to the salivary glands and the nose through the nerves of the face. Unfortunately, secretion of the virus in saliva and nasal secretions can come before any clinical signs are seen.

Wild Animal Reservoir of Rabies
The most common way the disease is spread is through a bite from an infected wild animal to a domestic animal. There are cycles of infection in the wild from skunks, bats and raccoons which allow the virus to continue to survive. Most of the cases of rabies in the United States are the result of one of these three wild animals biting a domestic animal. It is believed that the virus in skunks and bats is less virulent and they therefore have inapparent infections which mean these animals do not show any signs of infection. The infected llama was most likely bitten by a raccoon as there have been fifteen diagnosed in York County last year.

Because there is such a high number of wild animals that are infected it is unreasonable to think that the virus can be eliminated in areas that have a problem. This means that here is always going to be risk of exposure to rabies through wild animals and consequently the best way to prevent the disease is through vaccination. Even though, there is no labeled vaccine for alpacas it is thought that vaccination is protective.

The procedure for herds that have been exposed to the rabies virus depends on the vaccination history and local and state regulations. Contact either a local veterinarian or the Department of agriculture when there is suspicion of rabies in a wild animal for free testing or questions regarding procedures to follow. The recommendations are different whether the animal is the biter or the bitten. The biter if vaccinated in Pennsylvania is placed under 10 day quarantine, and if it is unvaccinated most of the time euthanasia and testing its brain is recommended. Six month quarantine after exposure for animals that are bitten is normal procedure in Pennsylvania. This means that no animals are able to enter or exit the premises. Quarantine by the Commonwealth requires the animal exposed to rabies to be kept on the owner's property to prevent other people or animals from being exposed in case that pet becomes sick with rabies. The Department of Agriculture will NOT seize or euthanize animals for being exposed to rabies! In some cases, the risk of a pet developing rabies may be so high that euthanasia is strongly recommend so that it does not get sick with rabies and put humans or other animals at risk. More information on quarantines related to rabies in Pennsylvania can be obtained through the Department of Agriculture.

Due to the low cost of the vaccine it is much safer and more economical to vaccinate all domestic animals including alpacas in areas that have rabies. The benefits of the vaccine to the public and the individual animal far outweigh the side effects that are commonly seen. Some of these side effects are localized swelling, low grade fever, and anaphylactic reaction. Anaphylactic reactions can occur when any vaccine or drug is administered and not reported to be anymore common with rabies vaccination. This is why vaccines should be administered by veterinarians who can treat these reactions properly. Please do your part and vaccinate against rabies.