Heart abnormalities in young dogs

Posted 3/13/19

Spaying and neutering your pets is very important. Veterinarians have been recommending spaying and neutering dogs and cats by six months of age for quite some time. Today, there are several opinions …

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Heart abnormalities in young dogs


Spaying and neutering your pets is very important. Veterinarians have been recommending spaying and neutering dogs and cats by six months of age for quite some time. Today, there are several opinions about spaying and neutering pets, particularly dogs, before 12 months of age. By delaying spaying/neutering until a dog is 12 months of age or older, it is believed that they would be healthier and less susceptible to some forms of cancer, have fewer orthopedic issues and better bone structure overall.

Recently, one of my patients, Zorro, was brought in to be neutered. Zorro is an eight-month-old German shepherd dog that lives with several other smaller dogs. Before surgery Zorro needed some important tests.

Sonogram of Zorro’s heart. This test allows us to examine the heart muscles, values and blood flow speed. This test is done without any anesthesia or pain.

Prior to all anesthetic events, it is strongly encouraged that all patients have several pre-anesthetic tests done. At our veterinary practice, this includes a pre-anesthetic electrocardiogram (ECG) that takes a 30-second electrical activity clip from a patient and electronically transmits that to the patient’s medical record. We are then able to send that 30-second strip anywhere in the world to be reviewed by a veterinary cardiology specialist. Each patient’s blood work is also taken and evaluated for proper blood cell counts, kidney function, liver function, blood sugar and electrolytes. We also test each dog for various tick-borne diseases and heartworm disease. These test results return in the hospital after 15 minutes.

After performing the tests on Zorro, we were extremely concerned with the findings on his ECG. It showed several abnormalities that would make anesthesia potentially life-threatening. Looking at him, you would have absolutely no idea that anything was wrong with Zorro. His lab tests were perfect. He is an extremely happy, active dog in good body condition. After sharing our findings, Zorro’s owners agreed to cancel the surgery and allow us to perform additional testing to evaluate his heart; we performed radiographs of Zorro’s chest and an echocardiogram (heart sonogram) that same day. Fortunately, nothing was structurally wrong with Zorro’s heart, but the next steps included a 24-hour ECG monitoring device called a Holter monitor. This monitor is applied to a patient’s chest without any sort of discomfort or distress. The patient is able to continue their normal activity while wearing the heart monitor and vest. Through a collaborative service with North Carolina State University’s Veterinary School’s Cardiology Service, we are able to offer this to all of our animal patients with cardiac disease.

The black arrows note abnormal heart beats called ventricular premature contractions (VPCs). 

When Zorro’s Holter monitor returned his test results, they showed several irregularities that were concerning. The monitor detected over 5,000 abnormal heart beats in a 24-hour period—quite significant. Zorro requires two heart medications to control the electrical activity of his heart. Without these medications, he is at risk of sudden death. Unfortunately, Zorro has been diagnosed with a genetic condition found among German shepherds. Some patients can outgrow these unexplained arrhythmias, but they will require medication until they’re two years old. Some patients will not outgrow the condition and require lifelong medications.

Fortunately for Zorro, the pre-anesthetic tests were performed, and we were able to identify these abnormalities before anything catastrophic occurred. If your dog, cat, horse, rabbit, or even potbellied pig is having a surgical procedure performed, proper pre-anesthetic testing is crucial. These tests could really save an animal’s life and save their families from heartache. 


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