Dear Doctor

Letters to the Tufts Veterinarians


A tumor in a testicle

Q During an annual wellness exam, our seven-year old golden retriever was found to have an enlarged, firm left testicle. Following surgery for removal of his testicles, this firmness was determined to be a mass diagnosed as a seminoma. According to our vet, the pathologist was unable to determine whether the seminoma was benign or malignant. My husband was told by his own urologist that there is no such thing as a benign seminoma. Could you please shed some light on this issue and tell us what the prognosis might be for this type of tumor.

Chris & Ed Stickell

Monkton, Maryland

Dear Mr. and Mrs. Stickell,

AWhat’s true in people is often true in dogs, but not always. That is, while your husband’s urologist told him there’s no such thing as a benign seminoma, in dogs, most seminomas are benign. And because your dog’s testicle with the tumor was removed, his prognosis is excellent, since even cancerous canine seminomas rarely metastasize, or spread, to other tissues. That is, castration does away with any potential problems.

Castration also cures a second type of canine testicular cancer called an interstitial cell tumor. Like a seminoma, it rarely spreads.

The only type of testicular cancer in dogs that can be life-threatening is a third variety called a Sertoli cell tumor. But it is dangerous not because is it prone to metastasizing. The issue here is that Sertoli cell tumors commonly secrete estrogen. In addition to “feminizing” a male dog — causing a smaller penis and gynecomastia, or mammary tissue development, and also making the dog attractive to other male dogs — Sertoli cell tumors cause bone marrow suppression. That leads to decreased production of white blood cells by the bone marrow, which can make the dog infection-prone. Thus, a dog with a Sertoli cell tumor should also be castrated, which will solve the problem.

Note that all testicular cancer in dogs is pretty rare, especially in the U.S., where most dogs are neutered early in life. If your dog is intact, it’s important to be aware that the most important underlying cause of testicular tumors in dogs is an undescended testicle. “Testicles like cold temperatures, which is why they’re in the scrotum outside the body,” says Your Dog Editor-in-Chief John Berg, DVM. “Something about the chronically warm environment inside the body if they remain undescended is probably what leads to their getting tumors,” he comments. “The descent should be complete by two months. If both testicles aren’t in the scrotum by then, that’s abnormal, and we recommend castration even if the owner intended on keeping the dog intact in order to avoid the possibility of cancer down the line.”

Sometimes an undescended testicle is inside the abdomen; other times, beneath the skin between the abdomen and the scrotum. “We perform an ultrasound to see where it is,” Dr. Berg explains, “and then either go into the abdomen surgically or, if it’s outside the abdomen, make a little incision in the skin and take it out through a little hole. It’s a fairly minor surgery either way, and if it’s in the abdomen, it can even be done laparascopically.”

Veterinary Information Network

Q I often tool around on the Internet looking for information about my dog’s health, and sometimes a website will come up called the Veterinary Information Network. But there’s no way for me to log on. It seems like it provides information for veterinary professionals but not for the public.

Michael Van Deuren

Somerville, Massachusetts

Dear Mr. Van Deuren,

AYou are right. The Veterinary Information Network, or VIN, as it’s called by those in the veterinary community, is not open to dog owners in general. But that does not mean your dog will not benefit from it. VIN provides a forum for veterinarians to ask questions of each other when they are stumped or dealing with a dog who has a condition that could use a specialist’s knowledge when it comes to treatment. In other words, it’s vets helping vets. Says Tufts veterinarian Mary Labato, DVM, who is board-certified in internal medicine, “I tend to use it for the reference books that they have available online. For example, I am able to quickly check a drug dose of a medication that I may not use often. Or I’ll log onto a chatroom overseen by a colleague who is a specialist in a particular field to see what he or she says about how they may handle a particular problem. Or I am able to perform a quick literature review of veterinary topics.”

VIN, which started in 1991, also offers support in that veterinarians can throw questions out to their colleagues in an informal way: Have

they ever seen such a thing, or how would they go about treating it? That is, there are interactive message boards. There are also virtual classrooms where veterinarians can log on for podcasts on a particular topic, and the “students” can interact with the specialists who are presenting their topics online. In addition, veterinarians can find at the site proceedings of meetings that they may not have been able to attend. These meetings often provide the latest in research on veterinary care.
“Cummings veterinary students use VIN a fair amount,” Dr. Labato says — “also interns and residents.” For people out in private practice, it’s particularly helpful, she adds. “At a vet school, we already have a community of specialists assembled all in one place.” But if you hang out a shingle and are practicing alone, “it’s an opportunity to throw ideas back and forth.” Veterinary technicians (think “nurses” for animals) are able to log on, as well.

Which food is right for my puppy?
Q I recently bought a Portuguese water dog puppy and, as is customary, purchased a food that the breeder suggested. However, while the kibble is labeled a puppy food on the front, the AAFCO designation in fine print says it’s “for all life stages.” I know that in the past you have recommended that the AAFCO designation on puppy food should be “growth.” What is the difference between the two? Not many brands make a “growth” formula, and I wonder whether the designation has become outdated because of modern advances.
Victoria Towns
New York, New York

Dear Ms. Towns,
AA food with a designation of “for all life stages” by AAFCO
(Association of American Feed Control Officials) will be adequate for your dog. “All life stages” covers the nutrient needs of all dogs: puppies, pregnant and lactating bitches, and non-pregnant male and female adult dogs. (Feeding an “all life stages” food is basically feeding a puppy food to all dogs.) Food that says “growth,” on the other hand, is designed for puppies — it’s more specific to dogs from birth through one year of age.
But what we really prefer for your puppy is a food that the AAFCO statement says has been put through feeding trials to insure adequate “growth” rather than simply “formulated to meet” the proper nutrient levels for “growth.” Why go with a food that has simply been formulated according to a set of standards rather than one that has actually been put to the test in real puppies to make sure they digest and absorb the nutrients properly?
Dog foods for “growth” that have been put through feeding trials are out there. They tend to come from larger companies that have been in business for a number of years, because putting a food through a feeding trial costs more in money and time than just producing it according to a standardized formula.
It is important to add here that while many breeders are indeed knowledgeable about the proper feeding of dogs, not all are, nor should they be expected to be. They are professional breeders, after all, not professional feeders. Canine nutrition is a science that is taught to veterinarians while they are students, which makes vets the safest bet for reliable nutrition information. For more complicated questions, you can also consult with a veterinarian who is board-certified in nutrition ( For more information on the proper feeding of your dog, see the World Small Animal Veterinary Association’s Nutrition Toolkit at


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