Everything You Want To know About Heart Worms In Dogs
Heartworm disease in dogs
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Definition of Heart Worms :
- Heartworm disease is the result of an infection by a worm diflaria Metis .- Heartworm infection is acquired by dogs after an infected mosquito takes a blood meal from the dog .
Pathogenesis of heart worms - Life cycle of heart worm:
To understand how to prevent heartworm disease in your dog let's take a look at the life cycle of the heartworm .
1- The life cycle of the heartworm begins when a mosquito feeds on a heartworm infected animal and ingests an immature microscopic stage of the heart worm called microfilaria .
2- Once inside the mosquito the microfilaria develop into infective larvae within one to four weeks depending on external temperatures when the mosquito takes its next blood meal from a susceptible host such as your dog the infected larvae are deposited into the skin surrounding the bite .
3- The infected larvae grow into the dog's skin for up to two weeks before migrating through the animal's body in the bloodstream after about two months the larvae arrive in the pulmonary artery where they will complete their maturation to adult worms in the following three months .
4- Once in the pulmonary artery the young adult worms fully mature to adult female heart worms can grow to 12 inches in length .
5- Mature worms will mate and produce offspring known as microfilaria that are released into the circulation .
The microfilaria circulate throughout the body waiting to be taken up by the biting mosquito the entire process from the initial mosquito bite to the adult female worms producing microfilaria requires between six and seven months depending on environmental temperatures .
6- Adult heartworms can live three to five years in your dog's body .
7- The microfilaria that they produce can survive one to two years in the bloodstream awaiting a mosquito to ingest them to restart the heartworm lifecycle .
8- Again all dogs are at risk of contracting a heartworm infection regions with constant temperatures above transmission year round northern climates that experience cold winters may have a break in the heartworm cycle during the colder months .
Signs of Heart worms in Dogs :
1- Infected dogs show many different signs of heartworm disease while coughing ,exercise intolerance or tiring easily are seen in most cases it is important to note that some dogs only show a decline in general condition.
2- Heartworms initially cause damage to the blood vessels around the heart over time the inflammation spreads to include the lungs .
3- The lung inflammation produces the classic Cough and breathing difficulties that are associated with heartworm disease .
4- If Dog left untreated the worm burden multiplies and the worms begin to move into the chambers of the heart comparing function if the infection still goes untreated the ever-growing population of worms begins to migrate toward the liver with acute death typically happening shortly ,thereafter heartworm infection creates a tremendous stimulation to the dog's immune system resulting in a profound inflammatory response throughout the body .
5- In the majority of cases heartworm disease that is untreated will result in a dog's early death .
Diagnosis of heartworm :
- Diagnosis of heartworm infection involves a simple blood test.
- The blood test commonly used called an antigen tests detect small pieces of the female worms body if the antigen test is positive then further testing needs to be done to determine the extent of the heartworm infection .
- Additional tests used to stage the disease include a blood test to check for the presence of microfilaria chest x-rays and an ultrasound of the heart .
Treatment Of Heart Worm In Dogs :
- Based on the results of the physical examination and these diagnostic tests your veterinarian will determine a plan for treating the heartworm infection .
- Safe treatment of a heartworm infection is done in phases the goal of the first treatment phase is to kill the adult heartworms.
- The only licensed effective treatment for heartworm infection is an injectable drug administered only by your veterinarian.
- Treatment for heartworm infection is not without risk the injection can cause serious adverse reactions which your veterinarian will discuss with you prior to initiating therapy the dog's immune system destroys and eliminates the dead adult worms this process of destruction creates a tremendous amount of inflammation in your dog's body .
- Your veterinarian will advise you to confine and strictly control the movement of your dog for several weeks after treatment as this is a dangerous time for your dog it will be critical to completely follow all instructions given by your veterinarian.
- As the adult worms are being treated your dog needs to be started on medication to kill the circulating microfilaria as well eliminating the microfilaria is important so that your dog does not act as a reservoir to continue the spread of the heartworm.
Prevention of Heart Worms in Dogs :
- To avoid this risky treatment protection is the best medicine .
- The main goal is to avoid this potentially fatal disease all together during your pets wellness exams .
- Your veterinarian will discuss a heartworm preventive medication that will be best for your dog available in tablet chewable or topical forms that are given every 30 days .
- Today's heartworm preventatives are affordable safe and effective for convenience some of the heartworm preventive medications are combined with drugs that prevent and control infections by intestinal parasites fleas and ticks .
- Ask your veterinarian about which preventive is best for your pet .
- Prevention of heartworm disease not treatment is always the goal for protecting our canine friends.
Treatment
ReplyDeletePrior to treating your dog for heartworm infection, your veterinarian will want a comprehensive medical history. Selecting the most appropriate treatment regimen will depend on many factors, including whether the dog has another disease that may influence the course of treatment, the number of worms present, and the extent of damage they have caused. Severely affected dogs may need medications to stabilize heart and lung disease before heartworm treatment.
The only drug currently available to treat infection with adult heartworms is melarsomine dihydrochloride, an arsenical compound. Appropriate treatment kills both mature and some immature heartworms. There are 2 approved treatment protocols, or methods, used for treating existing infections; a 2-dose protocol or a 3-dose protocol. In both cases the medication is delivered by injection deep into the muscles of the dog’s back, alternating sides of the back between treatments. About one-third of dogs will have some local pain, swelling, soreness with movement, or rarely a sterile abscess at the sites of the injections. The 2-dose protocol consists of 2 doses, 24 hours apart. The 3-dose protocol introduces a delay in the treatment schedule. Under this schedule, the dog would first receive a single injection. One month later, the second and third injections will be administered 24 hours apart. Many veterinarians choose to use the 3-injection treatment, regardless of the dog’s stage of heartworm disease, because it may be safer for the dog and more efficient at killing all the parasites.
Some veterinarians will prescribe medications before and after melarsomine. The antibiotic doxycycline can kill Wolbachia pipiens bacteria and young heartworms and reduce lung injury associated with melarsomine treatment. Preventive heartworm medications are also used to kill young larval stages. Corticosteroids can reduce inflammation associated with dying worms. Follow your veterinarian's instructions closely, and give medications as directed.
As a result of treatment, there is a risk that dead heartworms will cause severe respiratory problems, especially if dogs are not properly confined to restrict activity following treatment. These problems can occur from several days to 6 weeks after treatment of a heartworm-infected dog. The signs of post-treatment complications include coughing, spitting up blood, labored or rapid breathing, lethargy, lack of appetite, and fever. In dogs with complications of heartworm treatment, cage confinement, with several days of oxygen treatment and drugs to control inflammation and reduce blood clotting, may help alleviate the problem. If properly cared for, most dogs begin to recover from treatment complications within 24 hours.
To reduce the potential for such “dead worm reactions,” all dogs should be confined throughout treatment and for 4–6 weeks after the final injection of melarsomine. Dogs treated for heartworm should be placed on heartworm preventive drugs (usually before treatment with melarsomine) and tested after 8–12 months to be sure all worms were killed. For those dogs that test positive, retesting might be required and, if infection is confirmed, a new round of melarsomine will be needed.
Severely affected dogs can have worms in the heart that significantly block blood flow. These dogs may need surgery to manually remove the worms.