Cancer of the Testicles in Dogs

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Article Written by Dr. Daniel A. Degner, Board-certified Veterinary Surgeon (DACVS)

Key Points

Testicular cancer is very common in intact male dogs

Most tumors are contained to the testicles, but may spread in 10 to 20% of the cases

Surgery is the the treatment of choice

Prognosis is usually very good


Introduction

  • In one study showed that 27% of male dogs develop testicular tumors.1
  • Sertoli cell tumors, interstitial (Leydig) cell tumors, and seminomas are the three most common tumors.  Seminomas (42%) and interstitial cell tumors (50%) are most common with sertoli cell tumors being the least common (8%). About one third of dogs that develop a tumor will have more that one of these types of tumors present.  Other types of testicular tumors (i.e. embryonal carcinoma, lipoma, fibroma, hemangioma, chondroma, teratoma) can occur, but are rare. 
  • The current cause of testicular tumor development is unknown.   Male dogs that have one or both testicles that have not descended from the belly cavity are much more likely to develop a tumor than dogs with normal (scrotal) testicles.       
  • Undescended testicles (located in the abdomen or groin) are at increased risk to develop malignant behaving tumors (seminomas and Sertoli cell tumors). Tumors of normal descended, or scrotal, testicles are usually benign.  The tumor is slow to metastasize and the common site of spreading include lymph nodes.        
  • Testicular tumors can spread to regional lymph nodes, liver and lungs.
  • Specific tumors characteristics
    • Sertoli cell tumors
      • higher rate of spread than other testicular tumors
      • more common in undescended testes. 
    • Interstitial (Leydig) cell tumors
      • are benign and small 
      • show very few symptoms
      • these tumors are usually incidental findings 
    • Seminomas
      • arise from the cells of the testicle that normally produce sperm
      • majority are benign and they rarely spread. 
      • may produce estrogen and result in feminization 

 

testicular tumor Clinical Signs

  • Any breed can be affected and are found in older dogs (greater than 10 years) and obviously in intact males
  • Swelling of one or both testicles
  • Generalized scrotal enlargement
  • Infertility in the breeding stud
  • Effects of excessive estrogen levels due to tumor:
    • Symmetrical hair loss
    • Brittle hair
    • Poor hair regrowth
    • Thin skin
    • Hyperpigmentation (darkening of the skin)
    • Stripe of red inflammation along the midline of the prepuce (large arrow in photo right)
    • Nipple elongation (small arrow in photo right)
    • Mammary enlargement
    • Penile atrophy
    • Preputial swelling and sagging
    • Testicular atrophy of the unaffected (noncancerous testicle)
    • Prostatic atrophy or enlargement
    • Anemia
    • Behavioral changes:
      • Nipple
      • Squatting to urinate
      • Reduced sex drive
      • Attraction of other male dogs 

 

Diagnosis

  • A thorough physical examination including palpation of the testicles for a mass; the stripe of inflammation seen along the prepuce (arrow in the photo above) is classic for an estrogen producing tumor
  • Complete blood count (CBC) - to check for anemia
  • Biochemistry profile - to check internal organ health prior to surgery
  • Urinalysis +/- culture and sensitivity - to check for concurrent bladder infection
  • Chest and abdominal radiographs (x-rays) - to check for spread of tumor
  • Abdominal and scrotal ultrasound - to check for tumor and spread of tumor
  • Fine needle aspiration or biopsy - not commonly performed, but may be helpful to arrive at a diagnosis prior to surgery
  • Biopsy of the testicle after it is surgically removed

 

Treatment

  • Surgical removal of the testicles is performed. This surgery is typcially very routine, however the scrotal skin should also be removed to prevent the development of a large painful swelling of the scrotum after surgery.
  • Chemotherapy can be pursued if the tumor has metastasized.  Treatment of metastatic disease should be pursued. 
  • Radiotherapy

 

Potential Complications

  • The most common complication is marked swelling of the scrotum if it is not ablated at the time of castration.
  • Infection is uncommon
  • High estrogen levels may result in bleeding and anemia due to bone marrow suppression
  • Spread of the tumor will ultimately cause death of the patient

 

Care after surgery

  • Check the incision daily for 14 days for signs of infection: swelling, redness, pain or discharge.
  • A recheck in 10-14 days following surgery is recommended to evaluate incision healing. 
  • If bone marrow disease is present follow-up blood work will need to be performed to monitor for improvement in red blood cell, white blood cell, and platelet numbers. 
  • Patients with malignant tumors should be reevaluated every three to four months for recurrence or metastasis.  

 

Prognosis

  • Surgery is curative for most testicular tumors. About 10 to 20% of the cases have spread at the time of diagnosis.
    • Interstitial cell tumors and Sertoli cell tumors without spread or damage to the cells of the bone marrow have an excellent prognosis. 
    • Seminomas without signs of hyperestrogenism also have an excellent prognosis. 
    • Damage to the cells of the bone marrow (caused by the excessive estrogen levels) can be fatal despite therapy, but usually improves two to three weeks after tumor removal. 
    • The prognosis for testicular tumors that have spread is more guarded, but varies greatly depending on the location, type of tumor, and treatment options.    

References

  1. Grieco V, Riccardi E, Greppi GF, et al. Canine testicular tumours a study on 232 dogs. J. Comp Path 138: 86-89, 2008.
  2. McDonald RK, Walker M, Legendre AM, et al. Radiotherapy of metastatic seminoma in the dog. J Vet internal Med 2:103-107, 1988.
  3. Dhaliwal RS, Kitchel BE, Knight BL, et al. Treatment of aggressive testicular tumors in four dogs. J Am Anim Hosp Assoc 35: 311-318; 1999.

Frequently Asked Questions After Surgery

When should my dog have the first bowel movement after surgery?

  • Many dogs will not have a bowel movement for the first 4 to 5 days after surgery
  • Reasons that a dog will not have regular bowel movements after surgery include:
    • The dog has been fasted prior to surgery
    • Dogs do not eat well during the hospital stay
    • They frequently do not eat well when they go home
    • They are fed highly digestible food that produces little stool
    • Pain medication that contain narcotics (such as morphine, fentanyl patches, and tramadol) can be constipating
  • If a pet does not have a bowel movement on the 5th day of being home, a stool softener such as metamucil can be fed
    • Dose of metamucil is 1 tsp per 25 Kg mixed in with each meal (canned dog food); feed immediately after mixing, as the metamucil will gel the food and may make it less palatable

My pet had surgery and will not eat.  What can be done?

  • Dogs
    • Most pets will not eat their regular dog food after surgery, especially if it is kibble.
    • Offer a cooked diet having a 1:1 ratio of a protein source and carbohydrate source.  The protein source can be any meat (example: chicken breast, turkey breast, lean hamburger) that is low in fat and should be cooked (drain off all fat after the meat has been cooked).   The carbohydrate can be pasta, potato or white rice.
    • Try canned dog food; to enhance the flavor sprinkle a very small amount of garlic powder or chicken or beef broth (Chicken-in-a- MugTM or Beef-in-a-MugTM products)
    • Try Gerber strained meats for babies such as the chicken, beef, turkey, or veal
    • Try Hill's A/D diet available at most veterinary hospitals
    • Hand feeding: place a small amount of food in the mouth so that your dog gets the flavor
    • Warm the food slightly in a microwave, as the food will be more aromatic; stir the food before feeding and test the temperature on the bottom side of your wrist; it should only be luke warm.
    • Remember that most pets will not eat the first day or two after they get home from surgery
  • Cats
    • Offer smelly foods that contain fish such as tuna or smelly cat foods
    • Try Gerber strained meats for babies such as the chicken, beef, turkey or veal
    • Hand feeding:  with your finger place a small amount of food on the roof of your cat's mouth; use a syringe to get soft food into the mouth
    • Warm the food slightly in a microwave as the food will be more aromatic; remember to stir the food before feeding and test the temperature; it should be only luke-warm
    • Some cats will only eat dry food, try kibble if your cat normally has been fed that food
    • Petting and stroking your cat frequently will help to stimulate appetite
    • Remember that most pets will not eat the first day or two after they get home from surgery
    • Appetite stimulants such as cyproheptadine may be helpful
    • If your cat refuses to eat anything for 7 days a stomach tube or nasogastric tube should be placed to provide nutrition so that a serious liver problem (hepatic lipidosis) does not develop

My pet is vomiting.  What can be done?

  • The first thing for you to discern is whether your pet is vomiting or regurgitating.  Both will result in fluid or food being brought up.  Vomiting always will have heaving or retching of the abdomen prior to expulsion of the vomitus.  Regurgitation is not associated with heaving and the pet usually just opens the mouth and fluid or food will be expelled.  Usually the regurgited material will be clear or brown colored fluid. 
  • Next is to identify the cause of the vomiting or regurgitation.
  • Causes and treatment of vomiting after surgery
    • When some pets return home after a stay in the hospital they may drink excessive amounts of water at one time and then vomit; if this appears to be the case, the water should be limited to frequent smaller amounts.
    • Medications such as antibiotics, narcotics or nonsteroidal anti-inflammatory medication commonly cause vomiting after surgery.  In order to see which medication is causing the problem, the administration of each drug should be separated 2 hours apart.  Usually the pet will vomit or appear nauseated (drooling and sick look) within 1 hour of administration of the medication that they are sensitive to.  The antibiotic in some cases may be changed to a different one, or may be discontinued. 
    • Stomach upset from anesthesia is a potential cause of vomiting and will pass within a couple of days. 
    • An uncommon cause of vomiting after surgery is internal organ failure.  Blood testing will confirm this problem. For this reason vomiting should not be ignored if it persists for more than 24 hours.
    • If your pet had surgery of the bowels or stomach, vomiting is always a concern, as it may indicate that infection of the abdominal cavity, called peritonitis, is present.  Do not ignore this sign.
    • Symptomatic treatment of vomiting involves withholding food for 12 to 24 hours, then introducing small amounts of bland food such as rice and lean cooked hamburger, if your pet does not vomit after that then gradually wean him/her back onto the regular diet after 3 days.  In order to decrease the acidity of the stomach, Pepcid AC 0.5 mg/kg can be given by mouth twice daily for 5 days.  Metoclopramide and Cerenia are good anti-vomiting medications for dogs and cats.  You should always consult a veterinary healthcare professional before administering medication.
  • Causes and treatment of regurgitation after surgery
    • The most common cause of regurgitation is reflux of acid from the stomach into the esophagus while your pet is under anesthesia.  Acidic fluid from the stomach can cause a chemical burn of the esophagus and result in a bad case of heart burn, called esophagitis.  This results in poor motility of the esophagus, therefore water and food will accumulate in this structure.  In most cases, esphagitis is self-eliminating and will resolve within two or three days. 
    • If the esophagitis is severe the esophagus may develop one or more strictures.  A stricture is a narrowing or stenosis of the esophagus and does not allow passage of food down the esophagus, in regurgitation that lasts longer than one week.  This problem should be brought to the attention of your pet's doctor within the first two weeks so that it can be treated by ballooning the stricture (minimally invasive procedure, as it is done with the aide of an endoscope).  If an esophageal stricture is chronic surgery is needed.
    • Symptomatic treatment of regurgitation caused by esophagitis includes feeding bland food, and administering a coating agent (sucralfate) and an acid blocker (omeprazole or other).  Consult a veterinary health care professional if the regurgitation continues for more than a couple of days.

How do I know that my dog is in pain following surgery?

  • Signs of pain include
    • crying
    • biting if you get near the surgical site
    • grimacing (lips are pulled back and the the dog looks anxious)
    • tragic facial expression
    • panting
    • restlessness and unable to sleep; pacing
    • if abdominal surgery was done the pet will not lie down on the incision, or will continually sit up in spite of appearing very tired
    • the worst pain will be for the first 2 to 3 days after surgery

What can I do to control my dog's pain?

  • Narcotic medications that control pain: tramadol, butorphanol, Duragesic (fentanyl patch)
  • Anti-inflammatories used to control pain: Deramaxx, Rimadyl, Previcox, or Etogesic
  • If an orthopedic surgery has been done cold packing the surgical site may be helpful
    • A cold pack may be a pack of frozen peas, crushed ice in a Ziploc bag, or a cold gel pack; place a thin barrier between the skin and the cold pack.  An alternative to a cold pack is to freeze water in a styrofoam cup; after frozen cut the bottom of the styrofoam cup out. Cool the surgical site around the incision by rubbing the exposed ice directly on the skin in a circular pattern.  Cooling the surgical site helps to numb the area.

How do I know that my cat is in pain following surgery?

  • Pain is more difficult to assess in cats versus dogs, as signs can be more subtle and they usually do not vocalize when in pain
  • Signs of pain in a cat include the following:
    • biting if you get near the surgical site
    • growling or deep cry
    • not wanting to eat
    • hiding and not wanting to be near owner (remember that this could also be caused by the cat just being upset about leaving home and coming back)

What can be done for pain at home for my cat?

  • Pain medication such as buprenorphine or a Duragesic (fentanyl) patch
  • Tylenol will kill a cat as they lack abundant glutathione enzyme in the liver
  • Anti-inflammatories can be used, but the dose is much less than dogs

Is it okay for my pet to lick the incision?

  • If a dog licks the incision, the healing process may be delayed.
  • Licking can remove stitches and cause the incision to open
  • Licking can become a severe habit that is difficult to break
  • Licking can cause infection as the mouth has many bacteria
  • Dogs will frequently lick the incision when the owner is not watching such as at night time; if the skin looks red or excoriated the most common cause is from licking.
  • To stop your pet from licking the following can be tried:
    • Elizabethan collar can be placed on the neck; this will not help stop your pet from scratching at the region
    • Cervical collar (bite not collar) is a less awkward device and can be effective at stopping a pet from licking the surgical site
    • A tee shirt can be used to cover an incision on the chest or front part of the abdomen; gather the waist of the shirt up over the dog's back and wrap an elastic band around this part of the shirt.
    • A bandage or sock can be used to cover an incision on a limb; fasten the top of the sock to the dog's limb with tape.
    • Bitter apple can be applied around the incision; many dogs will continue to lick  after application of this topical
    • Bitter Apple and Liquid HeetTM (obtain this from a drugstore...it is used for sore muscles) mixed in a 2:1 ratio can be applied around the skin incision
    • Antipsychotic medication in some cases is needed

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What does it mean?

  • Four years of advanced training in surgery beyond the Doctor of Veterinary Medicine Degree

  • Experience in the development of new surgical treatments

  • Rigorous examination by the American College of Veterinary Surgeons to ensure competency in advanced surgical techniques

  • Assurance that a veterinarian is a surgical specialist

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