What is Canine Heartworm disease
Bichon Frise is a medium-sized beautiful dog breed with round black eyes and fluffy coat. Bichons like to stay inside the house and they love to interact with their owners and get excited when their owners are around. We have never had a Dog that contracted heartworms, but we always did all the preventative Measures
In this article, I am going to highlight the Canine heartworm disease and its importance in Bichon Frise dogs, and what you can do to diagnose the early signs and prevent the disease.
Heartworm disease is a deadly disease of dogs which can be fatal if not treated on time. This disease is transmitted to dogs through the bite of the mosquitoes.
Canine Heartworm disease is characterized by mild to severe signs including coughing, exercise intolerance which may lead to pulmonary damage, Cachexia, anemia, and ascites also develop in severely affected dogs. It can cause the death of the infected animal if it is not diagnosed and treated on time.
- Coughing ( sometimes coughing up Blood)
- Anemia
- Tired Easily
- Congestive Heart Failure
- Lethargic
Canine Heartworm disease is distributed in warm-temperate and tropical zones throughout the world including southern Europe and Canada. In Britain, it is only found in imported dogs.
This disease has found in all states and it has become much more widespread in North America in recent times, even special clinics were also created for treating heartworm infections.
This disease is caused by a parasite called, Dirofilaria immitis. The adult form of this parasite found in the right side of the heart and adjacent blood vessels of dogs and impair the normal heart function causing a condition called canine heartworm disease.
Dogs are the definitive host of heartworms, but it can also infect cats, wolves, and other wild canines and it can infect the man as well.
Canine Heartworm disease is more common in medium to large-sized dog breeds such as Bichon Frise and it is also more common in outdoor dogs than indoor dogs, dogs of all ages are susceptible.
How do Dogs get Heartworms
When a dog gets infected from this disease then it shows various clinical signs, there is a change of temperament that you can notice yourself and it can help you to diagnose the disease at early stages, hence the chances of survival of your pet can get higher.
But before we go into further discussion about this let’s have a little overview of the causative organism and its transmission into the dog.
Dirofilaria Immitis is a parasite and belongs to the phylum Nematoda, this parasite is transmitted by the mosquitoes (mainly Culex Spp., Aedes spp. and Anopheles spp.). The adult form of the parasite is present in the heart and adjacent blood vessels of the dog, where it reproduces and lay eggs which develop into the larvae, the larvae circulate into the blood.
These larvae are ingested by the mosquitoes during the bite, the larvae develop into advanced stages into the mouthparts of the mosquitoes. The mosquitoes transfer the advanced parasitic larvae to the other dog when the mosquito takes its blood meal from the dog.
This way the cycle continues. One thing to note here is that, mosquito bites at that part of the body where the hair coat is the thinner. However, having long hairs cannot prevent a dog from heartworm infection.
Disease progress inside the dog and Symptoms
Clinical signs and sickness become prominent only if the adult parasite are present in high number within the dog, while a low number of the parasite show no apparent illness.
In case of heavy infection, the circulatory distress occurs, primarily due to obstruction to normal blood flow and it leads to chronic congestive right-sided heart failure. The large number of parasitic presence cause swelling in the heart valves hence narrowing the blood pathways.
In addition, dead or dying worms can cause a pulmonary embolism (blockage in the lungs arteries). After a period of about nine months, the lungs and heart tissues start to show malfunction which may lead to congestive heart failure with accompanying signs of edema and ascites.
How to spot Heartworms Symptoms in your Bichon Frise:
Any dog including Bichon Frise doesn’t show any clinical signs at the initial stages of the disease, this is because the dogs can tolerate the worms at initial stages and show no apparent signs, and they look active, eat normal and exercise normally. As the number of worm increases the clinical signs starts to appear and they get worse as the population of worms increases.
Size of my Dog
Clinical signs also depend on the size of the dog. Smaller the dog means smaller its organs, which can easily get clogged even with the less number of worm population inside them.
It takes about 9 months for the development of Heartworms from larvae into the adult worms. During this time period the worms circulate within the bloodstream and complete their development, after that they lodge into the heart, lungs tissues and the blood vessels which serve these organs, this ultimately interferes with the normal heart function and respiration.
Bichons are medium-sized breeds, they are sensitive and their health status can be disturbed easily if they feel any kind of stress either inside or outside their environment. You should be concerned about your Bichon if they are having exercise intolerance, persistent cough with weak and lethargic temperament.
Duration of the infection
The severity of the signs also depends upon the duration of the infection i.e. for how long the worm is present inside the dog. If your Bichon has been bitten by the carrier mosquitoes multiple times at different days then it is quite possible that the different stages of Heartworm larvae are present inside its blood.
At the initial stages of the infection, the dog seems normal, as the worms population grows the health status of the dog gets worse.
Common signs include cough, dyspnea, and tachypnea should be considered seriously as they are sometimes misdiagnosed with pneumonia, bacterial or viral infections, so if you witness any of the above signs then you must consult your veterinarian for the proper diagnosis.
Reduced activity level of your Pet
One thing which is very common among the dogs suffering from Heartworms is exercise intolerance, this occurs due to the narrowing of blood vessels due to the presence of the worms inside them.
Bichons love to be gentle and friendly with you and they are very active when you are around, they love to go outside with you for a walk.
Experts recommend 20-40 minutes exercise/walk per day for Bichons, however, if you feel that your dog is not showing any interest in exercise or gets fatigued early during exercise then you should consider it very seriously as it might be a sign of damaged heart and lungs due to the presence of worm fragments which cause blockage of the blood vessels.
Infected dogs appear unthrifty & lethargic, they show labored breathing and gets tired early.
Moreover, if there is a large presence of mosquitoes in your area then you can also check for your dog’s recent activity as if it went outside in recent times which means that it probably might have bitten by the mosquitoes.
Symptoms to Watch For
Clinical signs can be seen as worms die or if blood clots or worm fragments block blood vessels. Visually there is a gradual loss of condition and exercise intolerance, you may witness chronic soft cough with hemoptysis (coughing up of blood).
In the advanced form of the disease, the dog may become dyspnoeic and it can develop ascites (accumulation of fluid inside the abdomen) and edema. Impaired circulatory system and pulmonary system in advanced stages, lead to hemoglobinuria, icterus and ultimately the death of the dog.
Abnormal heart and lung sounds, severe onset of lethargy and weakness accompanied by hemoglobinemia, hepatomegaly, syncope, and ascites occur at advanced stages which surely causes the death of the dog.
You can identify the disease at early stages by yourself via above mentioned common clinical signs, however, if you want to confirm your diagnosis then there are various lab tests available for the diagnosis of the Heartworms in your dog.
Diagnosis
If you are noticing a gradual change in temperament of your Bichon Frise and the signs and symptoms tell you about the possible Heartworm infection then the first thing you should do is to contact your veterinarian immediately.
Your veterinarian will do a thorough examination of your Bichon and will do necessary lab tests which may include, radiography, clinical laboratory findings, microfilariae detection, and serologic testing. On the basis of the severity of infection, your veterinarian will schedule a treatment plan for the disease.
Radiography:
This test will show the clear picture of your dog’s lungs, by which the severity of cardiopulmonary damage can be accessed. There is more cardio-pulmonary damage if the microfilariae (larvae) are larger in number. However, in recent times the radiography technique is replaced by the latest serological testing kits which assess the microfilariae presence in the blood.
Clinical Laboratory Findings
These tests are helpful in finding blood abnormalities including basophilia, neutrophilia, nonregenerative anemia, and thrombocytopenia.
Microfilaria Detection
Microfilaria is the larval stages of the Heartworms, these larval stages circulate within the blood from where they are transferred to the mosquitoes during the bite. Microfilaria can be identified microscopically by a drop of dog’s anticoagulated blood.
Serologic Testing
There are several commercially available antigen test kits. These tests detect a glycoprotein which is mainly secreted by the adult female heartworms. The sensitivity of these tests is 95% -100% and specificity of 100%.
Treatment
Heartworms are treated using adulticidal drugs (against adult worms) such as Melarsomine, which is only FDA approved drug for heartworm treatment.
The larval stages, especially under 2 months old, are treated with Macrocyclic Lactones, which causes a rapid decrease in circulating microfilaria (larval stages). Heartworm positive dogs are treated with Macrocyclic Lactones and Doxycycline before receiving Melarsomine injections. Along with specific treatment, there are anti-inflammatory, steroids and multivitamins that are also given to aid in treatment.
Preventive Measure against Heartworms
Prevention is always better than cure, you can do a lot of things to prevent this infection in your Bichon.
As the infection spreads from the bite of mosquitoes so you should consider using mosquito repellents while taking your dog outside. Especially if you travel and take your dog with you then you must immune your dog with preventive medicines.
These preventive medicines available in the form of oral pills which are given every six months while some are chewable pills which are given on monthly basis, these medicines cost less and they are very effective against larval stages of the Heartworms. If in case your dog has larval stages of the worm then it will be killed by these preventive drugs.
Vector (mosquitoes) control measures should be taken by the dog owners, mosquitoes repellent sprays can be used in your surroundings including lawns/backyards, it will limit your dog’s exposure to the vectors.
Moreover, microfilaria can also transfer from a pregnant bitch to its fetus especially when the bitch is highly infected with microfilaria.
Even if your bitch has recovered from the heartworm infection doesn’t mean that it is a hundred percent free from the parasite, microfilariae can survive in the dog’s bloodstream for over 2 years.
You can consult your veterinarian for possible complications in pregnant bitches and the growing fetus.
Public Health Considerations
Heartworms are of public health concern as well, although the number of infections in humans is very rare but still you should be careful especially if the Heartworm cases in your area are high or there is a large number of mosquitos presence in your area then you should be really concerned about having Heartworm infection in yourself as well.
The same organism D. immitis is responsible for causing the infection in humans causing nodules formation within the lungs tissues, these nodules resemble pulmonary adenocarcinomas in appearance. There are no serological tests available in humans for its detection, however, a biopsy is performed to confirm the infection.
Prevention can be best accomplished by using mosquito repellents, wearing protective clothing and remaining inside during mosquito feeding periods
