related terms: nevi, renal cystadenocarcinoma, uterine leiomyoma

What is nodular dermatofibrosis?

This is a condition in German shepherd dogs in which lumps (nodules) form on the skin, generally on the head and legs. In most affected dogs, the condition is associated with cancer of the kidneys (renal cystadenocarcinoma), or of the uterus in females that have not been spayed. The skin lesions are considered a marker for the internal cancer.

How is nodular dermatofibrosis inherited?

The mode of inheritance is believed to be autosomal dominant.

What breeds are affected by nodular dermatofibrosis?

German shepherd

For many breeds and many disorders, the studies to determine the mode of inheritance or the frequency in the breed have not been carried out, or are inconclusive. We have listed breeds for which there is a consensus among those investigating in this field and among veterinary practitioners, that the condition is significant in this breed.

What does nodular dermatofibrosis mean to your dog & you?

Skin lesions are generally first seen in dogs over 5 years of age. You will notice small, firm, usually painless bumps or nodules on your dog's limbs and/or head. Over time these will increase in size and number.  The lesions themselves cause few problems, although they may become ulcerated and painful as they grow larger. Most important however, is the fact that they are usually associated with cancer of the kidneys (or of the uterus in unspayed females).

The signs that you may see if your dog has kidney disease include increased drinking and urination, blood in the urine, loss of appetite and weight loss, a swollen abdomen (due to fluid retention or tumour size), depression, and vomiting.

How is nodular dermatofibrosis diagnosed?

Your veterinarian will surgically remove one of the skin nodules (a simple procedure done with local anesthetic) for examination by a veterinary pathologist. The biopsy will show changes characteristic of this condition.

Your veterinarian will also look for signs of kidney disease. S/he may be able to feel that the kidneys are enlarged or you may have already noticed some of the typical clinical signs listed above. Your veterinarian will also take blood and urine samples to look for indications of kidney disease, and likely also recommend radiography or an ultrasound.

How is nodular dermatofibrosis treated?

There is no specific treatment for this condition. The nodules can be surgically removed if they are large or painful, and generally do not grow back if excised fully (although new ones will continue to appear). Unspayed females should be spayed, to remove the potential of cancer in the uterus and also because these dogs definitely should not be bred.

Your veterinarian will carefully monitor your dog's kidney function. If cancer develops and appears to be confined to one kidney, that kidney should be removed. Otherwise it is a matter of providing supportive care for kidney disease as it progresses, such as a special diet and fluid therapy when needed.

Breeding advice

Affected animals should not be bred, and siblings and parents should be carefully examined for nodules.

Because nodular dermatofibrosis has an autosomal dominant mode of inheritance, all dogs with the defective gene will develop the condition. Theoretically it should be possible to eradicate this problem. However because signs do not appear until the dogs are over 5 years of age, it is quite possible that they have already been used for breeding. The best course is to discontinue breeding lines in which there are affected dogs. Although there are no screening tests, computed tomography (a radiographic technique) is the best way to detect early cases.

FOR MORE INFORMATION ABOUT THIS DISORDER, PLEASE SEE YOUR VETERINARIAN.

Resources

Moe, L., Lium, B. 1997. Hereditary multifocal renal cystadenocarcinomas and nodular dermatofibrosis in 51 German shepherd dogs. Journal of Small Animal Practice. 38:498-505.

Copyright 1998 Canine Inherited Disorders Database. All rights reserved.
Revised: December 17, 2001.

This database is funded jointly by the Sir James Dunn Animal Welfare Centre at the Atlantic Veterinary College, University of Prince Edward Island, and the Canadian Veterinary Medical Association.