Comparative Neurology Program

Spongiform Leukoencephalomyelopathy (SLEM) in Border Terriers

DNA test is now available!

Researchers at the University of Missouri, College of Veterinary Medicine and the Animal Health Trust in collaboration with Wisdom Animal Health have found the mutation associated with SLEM in Border Terriers. We are pleased to announce that a DNA test is now available to determine if a dog is a carrier of the mutation or at risk for SLEM. To order the test through the Orthopedic Foundation for Animals CLICK HERE. If you have any questions, please contact us.

What is spongiform leukoencephalomyelopathy?

Spongiform Leukoencephalomyelopathy (SLEM) is a hereditary disease of Border Terriers. When the pups begin to stand and attempt to walk, they show an uncontrollable shaking of their hind limbs causing a characteristic “rump shaking”.  As the pups develop, the shaking affected the entire body and their coordination is poor. Most pups are euthanized due to a poor quality of life but there are reports of dogs improving with intensive nursing care.

The nerve cells in the brain communicate with each other through electrical signals. These signals are conveyed from one area of the brain to another through extensions of the cell called axons. Like an electrical cord, the axons must be insulated to keep the electrical signals from shorting out. The insulation of the axons is called myelin. If the brain is cut at a post-mortem exam, the myelin gives the bundles of axons running from one area of the brain to another a glistening, white color, so these areas are called "white matter". If the insulating myelin does not form properly, then areas of the brain cannot communicate with each other efficiently. The poor communication affects the ability of the puppy to control movements resulting in the signs of SLEM.

When post-mortem examinations were performed on affected pups, they found that the myelin had not formed properly in areas of the brain and spinal cord. In a normal pup, the dense insulation appears purplish-pink when the tissues are stained for examination under the microscope. In the affected pups, there are basically holes where the insulation should be giving the tissue a spongy look. So the condition is termed spongiform leukoencepahomyelopathy: spongiform (like a sponge) leuko (white)- encephalo (brain)- myelo (spinal cord)- pathy (disease). We call it by the initials SLEM.

SLEM in Border Terrier

The nerve cell fibers in the brain are insulated like an electric wire. Under the microscope, this insulation looks light purple in the normal brain on top. When the insulation (myelin) does not form propoerly, ther brain has a spongy look (spongiform) as seen in the picture at the bottom of the brain from an affected pup.


Puppies with SLEM show a characteristic "rump shaking" tremor as soon as they begin to stand and walk.

What else can look like SLEM?

There are other diseases that can affect myelin or the areas of the brain that control movements and cause tremors and loss of cooridnation. The "rump shaking" movements that these pups make, however, are fairly characteristic of SLEM. Canine Epileptoid Cramping Seizures (CECS) also affects Border Terriers and causes shaking. CECS develops at a later age and is the shaking occurs as discreet episodes like seizures whereas pups with SLEM are affected from the time they begin to stand and the signs occur whenever the pup tries to stand or move.

Thanks!

We would not be able to conduct this research without the help of breeders, dog owners and veterinarians who provide us with samples and information. Thanks for all your help!

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The Canine Genetic Diseases Network is a group of researchers dedicated to eliminating genetic disease in dogs