Heartworm test. Positive test result. A blood sample was added to the sample well. A positive control spot and D. immitis spot are colored, indicating the presence of the Dirofilaria immitis antigen.

Heartworm Disease in German Shepherds

Heartworm Disease in German Shepherds: How To Detect

If you suspect your German Shepherd is suffering from heartworm disease, it is important to have him assessed by a veterinarian to determine the severity of the infestation. The veterinarian may ask to have blood tests done to determine the stage of the disease. The blood sample taken may also be used for the canine heartworm antigen test and microfilaria test.  

A Heartworm Test indicating the presence of the Dirofilaria immitis antigen in the blood.

The canine heartworm antigen test is the most commonly used method for detecting adult heartworm infection. It helps specifically detect the antigens produced in reaction to the presence of adult female heartworms. However, these antigens can be detectable only 6 to 7 months after the infection. It may reveal the approximate number of adult females present.  

But, this antigen test may also show false negative if: 

  • it is done too early in the infection 
  • there is only a small population of heartworms 
  • the heartworms are all male 
  • the heartworms are young females 
  • there are errors in conducting the test 

If the canine heartworm antigen test kit reveals a positive diagnosis, the veterinarian may also ask for a microfilaria test. This test shows the presence of microfilaria in the blood confirming that adult heartworms are present in the heart. There are different methods for detecting microfilaria in the blood, including concentration tests, such as the Knott’s test and the filter test.  

Depending on the veterinarian’s assessment, other laboratory tests may also be done to see if there are abnormalities in your German Shepherd’s internal organs linked to the presence of heartworms. Here are some of the other tests that may be done on your German Shepherd. 

  • Radiographs (X-rays) – This can be used to detect inflammation, enlargement, or swelling of the lungs and the heart. 
  • Ultrasound – An Echocardiography (not abbreviated as ECG) can also help check if the heart is healthy enough for treatment. This test can also confirm the presence of heartworms in the heart and  
  • ECG – Electrocardiogram (ECG) can detect abnormal heart rhythms. This test can also detect enlarged heart chambers. 


Treating Heartworm Disease in German Shepherds

Heartworm disease is a terrifying condition. However, it is treatable although the treatment is long and expensive. There are different ways to treat heartworm in dogs, and vets usually assess the case of each dog to determine which method is better for your pet. 

During the course of treatment, antibiotics may also be given to your German Shepherd, as Wolbachia bacteria can be present alongside heartworms. The bacteria are released by heartworms die when they die causing an immune response that can worsen your German Shepherd’s condition. This reaction may also result in inflammation of lungs and kidneys. Also, if your German Shepherd has another serious health issue, the vet may opt to address that issue first before proceeding with heartworm treatment. 

Here are some of the methods used in treating heartworm disease in German Shepherds. 

Option 1: Combination of Heartworm Preventatives and Melarsomine 

The vet may prescribe heartworm preventatives, a course of antibiotics, and steroids prior to proceeding with the adult heartworm treatment. Heartworm preventatives kill young heartworm larvae and unless it is done, the treatment for adult heartworms may not be effective, as the larvae (microfilaria) will grow up again. For this, veterinarians commonly use Ivermectin. There are also other medications that can kill heartworm larvae like milbemycin. But a lot of vets prefer using Ivermectin because it kills more slowly. Killing microfilaria too quickly can cause shock, collapse, and blood vessel blockage. This step often takes 1 to 3 months depending on your German Shepherd’s condition. 

After being given a course of heartworm preventatives, your vet determines if your pet is ready for adult heartworm treatment. Currently, the medication that is known to kill adult heartworms effectively is melarsomine. This organic arsenic drug is injected deep into the back or lumbar muscles. These injections can be very painful for your German Shepherd. To reduce the pain and discomfort, pain medications are often given concurrently with these injections. 

There are also two protocols veterinarians follow when treating heartworm disease using melarsomine. 

  • First Protocol – This protocol is advised for dogs who the vet thinks are healthy and not showing significant and serious signs of heartworm disease. They are given two injections of melarsomine with 24 hours interval. 
  • Second Protocol – This protocol is the most common and all infected dogs regardless of their age and stage in the disease receive 3 melarsomine injections – first melarsomine injection, the second injection a month later, and a third 24 hours after the second. 

The second protocol is the most recommended for melarsomine-based treatment because it is slower and safer. Remember, the slow treatment is better to tackle heartworm disease because of less chance of adverse effects.  

It is recommended to let your German Shepherd stay with the vets on the days the melarsomine is given. Your German Shepherd may experience adverse reactions after the injection so having a veterinarian nearby to look after him is recommended.  

Option 2: Slow-kill Treatment 

Depending on the condition of the dog, some veterinarians recommend using the “slow kill” method for treating Heartworm Disease. This treatment option involves using monthly heartworm preventatives to kill heartworm larvae and waiting until the adult worms die a natural death.  

This treatment option is only recommended for dogs (usually senior dogs) who are not healthy enough for the melarsomine treatment. This option can take a very long time as adult heartworms can grow as old as two years before dying. With that much time, they are still capable of damaging the heart, the lungs, or both. 

Option 3: Surgery 

There are cases wherein surgery is needed to treat heartworm disease. If heartworms reach the caudal vena cava, a large vein found between the liver and the heart or when the heartworms fill the whole right side of the heart choking the blood vessel that leads into the heart, surgery is the only option. 

Post-Treatment Care 

It is very important that you limit your German Shepherd’s activity during and after any treatment option to decrease chances of complications. This helps to prevent dead worms from blocking the blood flow through your German Shepherd’s pulmonary vessels. If your pet keeps on working out, blood flow may increase to blocked areas and this may cause the capillaries to rupture as the heart pumps blood through them. This results in breathing difficulties and even death. 

During the course of treatment, it is highly recommended to give your German Shepherd a complete crate rest except potty walks and in-house roaming.  

Even the treatment is finished, let your German Shepherd undergo retesting after six months. This is to make sure that all of the microfilariae, larvae, and adult heartworms are gone.  


Preventing Heartworm Disease in German Shepherds

Preventing the disease is always better and less expensive than having it treated. There are heartworm preventatives available in the market that not only protect your dog from heartworms but also kill other parasites. You can choose between monthly pills, spot-on treatments, or 6-month injections.