C O L D  R I V E R  V E T E R I N A R Y  C E N T E R

Integrated approach to heartworm disease

CASE REPORTS

• Allergies in a dog

• Allergies in a cat

• Arthritis

• Colitis. otitis

• Cushings disease

• Ear infections

• Feline chronic renal failure

• Heartworm

• Inflammatory bowel disease

• Kennel cough

• Kidney failure, disc disease

• Lymphangitis

• Lymphoma

• Oral papillomas

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Heartworm disease (dirofilariasis) is caused by infection of a blood-borne parasite (Dirofilaria immitis), which is carried by mosquitoes. The prevalence of heartworm varies widely with high levels of infestation in the Gulf Coast states and low incidence in the Northeast. Heartworm preventive medications are probably among the top 5 drugs sold for dogs in the United States. Occasionally dogs acquire infection who are not on a preventive medication and live in a heartworm-endemic region. While we rarely see heartworm-infected dogs native to New England, we have treated dogs who were infected when they were living in high-risk areas.

Heartworm infection from Texas

Savanna is a 5 year-old spayed female adopted through Doberman Rescue in Texas. She was given a new home and loving family in Vermont at age 3. She had a history of unintentional head tremors. On her physical exam at CRVC in June, 1998 she had a heart rate of 78, respiration rate = 30, slightly pale mucus membranes, normal vulvar mucosa, healthy skin and coat. Savannah had a normal range of motion of her neck, without pain. She had a mild scoliosis (lateral deviation of the spine) and muscle tension in the right scalenius muscle, but was otherwise in fine shape. Savannah was on phenylpropanolamine, a drug commonly prescribed for urinary incontinence. We discussed heartworm prevalence in Vermont and how to prevent the infection naturally (see below). Much to our surprise, a  routine canine heartworm antigen test was positive.

A positive heartworm antigen test indicates the presence of adult heartworms in the circulation. These patients are not treated with preventive medications that kill larvae, but with an arsenic-based medication effective against adult worms. 

Further blood tests showed microfilaria (heartworm larvae) on a direct smear and a Knott's test. In addition, a fecal test showed hookworm infection (Ancylostoma) which was treated with an anthelmintic (worming medication).

Due to the risk of heart and lung injury, the decision was made to have Savannah treated at CRVC with intramuscular injections of Melarsomine dihydrochloride ("Immiticide") to kill adult worms. Our job was to limit all the possible adverse effects of this drug.

Prior to treatment with the adulticide (Melarsomine) we took radiographs shown here, of  the thorax to identify changes to the pulmonary vessels that would suggest a heavy burden of adult worms.

Radiographs revealed a "reverse-D" cardiac silhouette, prominent right atrial appendage, right atrial enlargement, irregular pulmonary arteries, and an interstitial lung pattern.

With the permission of Savannah's caregivers we cautiously initiated treatment for heartworm disease.

How do dogs get infected with heartworm?

The lifecycle of canine heartworm (Dirofilaria immitis) begins when a mosquito bites a dog that has an infection. Adult female worms in the dog produce first-stage larvae called microfilariae. These larvae (L1) are picked up by mosquitoes that take a blood meal from the dog. Once L1 larvae are inside the mosquito they must undergo two molts in order to be infectious to another dog. The L3 larvae in the mosquito can be transferred to another dog, starting a new infection. Dogs can develop adult heartworms (and therefore heartworm disease) 6 months after being inoculated with infectious larvae.

Treating heartworm disease

At CRVC we take an integrated approach to the treatment of disease. Integrative medicine combines conventional diagnoses and treatments with traditional or complementary therapies that promote healing, support normal physiology, and restore good health. The purpose of integrating conventional or allopathic medicine with natural medicine is to improve patient well-being and ultimately bring about a positive patient outcome or cure. 

For heartworm treatment our goals are to:

1. Provide a low-stress environment for inpatients being treated for heartworm disease 

2. Place an intravenous catheter to maintain hydration, and administer vitamins and antioxidants 

3. Administer Melarsomine according to the label

4. Monitor the patient for potential complications as the adult worms die in the circulation

On an August morning, 1999, Savannah arrived for her treatment with Melarsomine but her temperature was subnormal at 98.9 F. We started Savannah on intravenous fluids with vitamin C,  potassium, and B-vitamins to support cardiac function, reduce inflammation, and to help her excrete or detoxify the arsenic-based medication after the worms would have been killed. She also received natural pet foods and nutritional supplements during her hospital stay. Fortunately Savannah did not have signs of heart failure or respiratory distress from heartworm in the pulmonary arteries. Her Melarsomine treatment was continued according to the manufacturer's instructions, without complications. Some minor swelling occured at the injection site as the medication is slightly irritating. Her temperature on re-check three weeks later was normal at 101.3, heart rate = 120. Savannah's subsequent heartworm antigen test in May, 2000 was negative! She remains negative for heartworm antigen in 2001, and her caregivers follow our recommendations for heartworm prevention.

Heartworm prevention

Is there a natural alternative to monthly heartworm medications? We take an integrated approach to heartworm prevention as well as treatment. The guidelines we have established depend on the individual’s risk of infection.

1.    Dogs in the Northern States do not need heartworm prevention year around, though we have heard from clients who were sold on this idea. Mosquitoes transmit the infective larvae (microfilaria); if there are no mosquitoes, there is no transmission.

2.    Test all dogs every spring for heartworm antigen (a blood test). If the test is positive see your veterinarian for treatment of heartworm infection.

3.    Dogs with an indoor lifestyle have less risk of mosquito exposure than sporting and working dogs who spend much of their time outdoors.

4.    Insect repellents may help reduce the number of  mosquito bites and therefore the transmission of heartworm infection to the dog. Like people, horses and dogs exposed to mosquitoes or other biting insects would appreciate an application of a natural bug repellent when the pest pressure is high, i.e., evenings and during peak outbreaks. 

5.    Exclude flying insects from indoor areas with window screens. Provide good air movement around outdoor pens or runs. 

6.    Animals with a healthy immune system and good diet are less susceptible to infections than homeless strays and debilitated pets. 

7.     Dogs at high risk of infection should take a heartworm preventive medication during the mosquito season (available by prescription).

Heartworm infection from Alaska

Katy is a 9 year-old spayed female Alaskan Malamute who tested positive for heartworm antigen and had microfilaria on a blood smear examination. She had a history of fibrosarcoma that was surgically excised in June, 1999. When Katy moved to New Hampshire she was referred to us by her holistic veterinarian who was now too far away to provide the heartworm treatments. Fortunately her primary veterinarian had started Katy on a program of nutritional and immune-supportive supplements, natural thyroid, and a homeopathic nosode. When first seen at CRVC in May 2000 Katy was not exhibiting signs of heart failure from heartworm infection.

On physical exam Katy had an S3 gallop heart rhythm, rate = 96.  Both anal glands were very full and needed to be expressed, producing a cast of pastey brown material consistent with a bacteria infection. Her temperature was subnormal = 100.2 F and she had a harsh, dry hair coat. Her body condition score was 2.5/5 (slightly thin). She had increased sensitivity over the dorsal spinous process at the fourth and fifth lumbar vertebrae suggesting some intervertebral disc disease. Two subcutaneous nodules were palpated on her mammary glands.

When Katy's subcutaneous mammary nodules continued to proliferate, we biopsied the tissue to rule out a malignancy. The cytology report indicated these were benign cysts (see photograph right; the nodules are below the far teat). We prescribed nutritional therapy including calcium glucarate to facilitate clearance of harmful estrogens that are tumor promoters. The cystic mammary nodules resolved.

Normal anal sac glands have a thin fluid secretion with a pungent odor. Too many dogs get impacted anal glands with a viscous secretion that may become inspissated (hardened) and nearly impossible to express. This cast (pictured at right) was removed with some effort from Katy's anal gland. We have observed that dogs with impaired fat metabolism (as from hypothyroidism), fatty acid deficiency, bacterial infections, or who eat a low-fiber diet are at risk for abscessed anal glands (anal sacculitis) and potentially, anal sac carcinomas.

Heartworm treatment

Katy received an integrated heartworm treatment much like Savannah, complete with intravenous vitamin C. Here she is in June 2000 at CRVC, with her IV catheter, taking a break outdoors from the IV vitamin infusion and the Melarsomine treatment. Like Savannah, Katy showed some local muscle irritation from the drug injection. This resolved after we applied a natural liniment made with Arnica (Leopard's Bane herb) and Cayenne (red pepper extract) over the affected muscles.

Ten days later her anal gland ruptured, with a serosanguinous (clear, bloody) discharge. A short course of antibiotics was prescribed. After 10 days, the serosanguinous discharge appeared again. This was treated topically with DMSO (an anti-inflammatory liquid) and the abscessed healed. We prepared a nutritional analysis (BioMedical Profile) and prescribed some nutritional supplements to improve her thyroid level, heart function, and mineral balance. 

Follow up

On a re-check in May 2001, Katy glowed with good health. Her heart rate was 78, with normal rhythm. Her body condition is ideal at 3/5 and she has a beautiful coat. Katy's spring heartworm test was negative. The results of our nutritional therapy are summarized in the table below.

Serum chemistry profiles

    *These values are at one end or outside of the reference range for dogs.

The plant world is rich in natural pest controls including aromatic compounds that repel biting insects. We use the natural botanical insecticides, Neem and Citronella as a spray and shampoo to control fleas and ticks. For mosquitoes, black flies, and other flying insects a natural repellent such as "Buzz Away" is safe. Buzz Away  is made from Citronella, Cedarwood, Eucalyptus, Lemongrass, and Peppermint. Available from:

Quantum Inc., 754 Washington Street,  Eugene, OR 97401    Tel. 1-800-448-1448  www.quantumhealth.com

  William Konrad Kruesi, D.V.M. /2001, 2005