Text and Photos by Emmanuel D. Macapagal, DVM
Additional research and text by CFB
Illustration by Greco Milambiling
Just when most people thought that sexually transmitted diseases were the exclusive domain of humanity, we find it is also present in the animal kingdom. For instance, there is rabbit syphilis, a bacterial disease caused by the spirochete Treponema cuniculi. There is an equine venereal disease in horses called “contagious equine metritis” as well as “equine coital exanthema,” caused by equine herpesvirus 3.
As I am a dog and cat medical practitioner, I will zero in on the diseases that affect dogs, particularly the transmissible venereal tumor or TVT. While the etymology of the term “venereal” refers to the Roman goddess of sexual love, Venus, we think of venereal diseases to refer to diseases transmitted by coitus. Medically speaking, though, this is not always true.
TVT is known to us by many names: contagious canine condyloma, contagious venereal tumor, and infectious sarcoma. It mainly afflicts canids: dogs, foxes, coyotes, and jackals. Both males and females are equally susceptible.
TVT is contagious and spreads through dogs that are intact or not neutered, and/or are allowed to roam around unrestrained—especially when they are already in the reproductive stage—as they have a higher likelihood of contracting this disease. In my clinical practice, the usual signs are unexplained bleeding near the prepuce of the male dog, or the vulvar or vaginal area in the case of the female dog, as well as a foul-smelling odor in the area of the cauliflower-shaped tumor mass.
Whenever veterinarians suspect that the cause of a bloody discharge or blood-tinged urine is caused by TVT, the usual precautions apply whenever patients come in for a routine physical exam. There is no reason, however, to suspect that humans can be affected, but prudence dictates that you should protect yourself in the light of new scholarly articles that suggest that it may be transmissible to humans.
This kind of tumor is easily friable (bleeds easily upon manipulation) and is not limited to transmission via sexual contact; it can also be spread orally since dogs are in the habit of greeting each other by smelling as well as licking one another. Thus this “STD” is not your usual sexually transmitted disease but a transmissible neoplasm, a kind of cancer.
What we do understand nowadays is that this is usually transmitted through the mating of dogs with those of their kind that are carriers of the tumor cells. Routine tests for diagnosing the disease include a complete history taking, physical examination of the lesion (affected area of the body), hematology, and a serum chemistry panel.
Although some authors suggest that other laboratory tests are not necessary, I on the other hand insist on a basic hematologic test to ascertain the dog’s fitness for chemotherapy, as this treatment might aggravate any undiagnosed organic failure. In my clinical practice, I usually observe that this disease is prevalent among dogs that freely roam, are sexually active, and live in urban areas (regardless of whether these are temperate, subtropical, or tropical).
A three-year-old female dog brought into the clinic where I once worked as an associate presented with unexplained bleeding near its genitalia. Upon further examination of this dog, I observed a cauliflower-shaped tumor surrounding its genitalia as well as some parts of the perineum where bleeding was observed; it was exuding a foul-smelling odor and was pus-filled. The margins of the tumor were punctuated with ulcerations and some parts of the tumor were bleeding.
In some other instances where a cough is observed, it would be wise to perform thoracic imaging to determine metastasis, which is unlikely if diagnosed earlier.
I prefer chemotherapy over surgical excision to minimize post-operative disfigurement at the site of operation. Many owners don’t know that the recurrence of this kind of tumor is not a good sign, for it may cause bigger tumors to appear; if operated upon once more, these might induce the spreading of tumor cells to nearby areas. It is possible to for these tumor cells to grown on parts of the skin other than the genitalia.
Chemotherapy involves the use of an anticancer agent that arrests oncogenic (tumor) growth by preventing cell division of cancer cells. The usual regimen is given at a specific dose, once weekly every week for 6 weeks until clinical remission of the tumor is achieved. That being said, the tumor is no longer visible (perceptible) through palpation.
My clinical experience has been filled with dramatic remissions in patients that were considered hopeless, as well as dismal failures that had a poor to grave recurrence and/or prognosis. Let me assure readers that this disease has a better chance of recovery if treated earlier through chemotherapy by a duly registered veterinarian specializing in companion animal medicine. As they say in medicine if symptoms persist, consult your doctor. After all, if the bleeding becomes too frequent, that might be TVT.
Moral of the story: To prevent TVT, spay your dog if you do not intend to mate it or better still, do not allow your dogs to roam around without a leash.
Morrison WB. Cancers of the Reproductive tract. In: Morrison WB, ed.: Cancer in dogs and cats: medical and surgical management. Baltimore: Williams & Wilkins, 1998: 581-590.
Rosa Maria Paramo Ramirez. Transmissible Venereal Tumor. Etienne Cote. Clinical Veterinary Advisor. Missouri: Mosby Elsevier, 2007: 1101-1102.
http://www.merckvetmanual.com/reproductive-system/canine-transmissible-venereal-tumor/overview-of-canine-transmissible-venereal-tumor· http://www.petmd.com/dog/conditions/cancer/c_dg_transmissible_venereal_tumor· http://www.nature.com/news/how-a-contagious-dog-tumour-went-global-1.14580· http://www.tcg.vet.cam.ac.uk/about/ctvt· http://www.veterinarypartner.com/Content.plx?P=A&S=0&C=0&A=1650· http://www.slate.com/blogs/wild_things/2014/01/30/contagious_cancer_in_dogs_the_std_canine_transmissible_venereal_tumor.html
This appeared in Animal Scene’s February 2017 issue.