Renal cystadenocarcinoma and nodular dermatofibrosis

What is ... ?: 

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.

How is ... inherited?: 

The mode of inheritance is autosomal dominant with complete penetrance.

What does ... 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, loss of appetite and weight loss, a swollen abdomen (due to fluid retention or tumour size), depression, and vomiting.

How is ... 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 ... 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 - both kidneys are usually affected. Your veterinarian will discuss with you supportive care for your dog as kidney disease 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. Hereditary multifocal renal cystadenocarcinomas and nodular dermatofibrosis in 51 German shepherd dogs. Journal of Small Animal Practice. 1997 38:498-505.
 
Pressler B. Cancer and the kidney. In: Bonagura JD, Twedt DC, eds. Kirk's Current Veterinary Therapy XIV. Missouri: Saunders Elsevier, 2009:928.
 
Sargan DR. Renal cystadenocarcinoma and.... In IDID - Inherited diseases in dogs:web-based information for canine inherited disease genetics.


What breeds are affected by ... ?
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