Tag Archives: lethargy


Heartworm live in the heart and major blood vessels of infected dogs.

How do dogs get heartworm?

Female heartworm produce millions of young, or microfilaria, which live in the bloodstream. Mosquitoes ingest microfilariae when they bite an infected dog.

The microfilariæ develop further in the mosquito. When the mosquito bites another dog it injects larval heartworm. These larvae migrate to the heart and adjacent vessels over a few months, and grow to adult heartworm.

Usually dogs do not show outward signs of infection for a few years.

How do heartworm affect dogs?

Adult worms:

Adult worms clog the heart and the major blood vessels leading from the heart. They stop the heart valves from closing and reduce blood supply to the rest of the body.

The most obvious signs are: a soft, dry, chronic cough, shortness of breath, loss of stamina, and weakness, especially after exercise. Heavily infected dogs may faint.

Sometimes we hear heart murmurs or abnormal lung sounds with a stethoscope. In advanced cases the abdomen and legs swell with fluid accumulation. Weight loss, poor condition, and anaemia develop with a chronic infection.

Severely infected dogs may die suddenly during exercise or excitement.

Microfilariæ (Young worms):

Microfilariæ circulate throughout the body but prefer small blood vessels. Because they are as wide as the vessels, they may block blood flow to vital organs such as the lungs, liver and kidney.

How do we prevent heartworm?

Annual injections of Proheart SR-12, or monthly tablets such as Heartgard or Proheart, or spot-ons such as Advocate or Revolution all kill larval heartworm before they reach the heart.

Before starting a preventative we run a blood test in the surgery to check for any existing infection.

If we detect an existing heartworm infection an effective treatment is available. Before admitting an infected dog for treatment we screen for damage to the liver, kidneys, heart and lungs to reduce the chance of complications.



Hookworms attach to the intestinal wall with hook-like mouthparts. They are hard to see because they are only about 3 mm long and very thin.

Dogs are infested with hookworms in one of three ways:

1. Hookworm larvae pass from the dam to the pups through the placenta before birth

2. Pups ingest larvae in the mother’s milk

3. Larvae penetrate the skin


What problems do hookworms cause?

Hookworms suck blood from the tiny vessels in the intestinal wall and cause anaemia especially in puppies.  Pale gums, lethargy and weakness are signs of anaemia.

Hookworm also cause bloody diarrhoea, weight loss and failure to grow.

Hookworm larvae burrow into the skin and cause itching and discomfort in a heavily infested environment such as kennels.


How do we diagnose hookworm infestation?

Hookworms produce a lot of eggs which are easily found in faeces under a microscope. Faecal examination is less reliable in very young puppies.


How is hookworm treated?

Most broad spectrum wormers, like Milbemax and Drontal, kill adult hookworms. We repeat the treatment 2-4 weeks later to kill the next wave of larvae maturing into adult worms.


Are canine hookworms infectious to people?

Adult hookworms do not infect humans. However, hookworm larvae can burrow into human skin and cause itching. They do not mature into adults. Wear shoes to avoid skin contact with hookworm infested soil especially in wet weather.


How do we prevent hookworm infection?

1. Deworm pups at six weeks of age

2. Deworm pets at high risk of reinfestation

3. Pick up and dispose of dog faeces, especially in yards, playgrounds, and public parks.

4. Do not allow children to play in potentially contaminated environments.

5. Treat nursing bitches concurrently with their pups.

6. Use broad spectrum worm treatments that are effective against hookworms.



The thyroid gland regulates the body’s metabolic rate. When it slows down the whole body slows down.

Hypothyroidism is a deficiency in production of the thyroid hormone. This deficiency is caused by immune-mediated destruction of the thyroid gland, most commonly, or by natural atrophy of the gland.

Signs of hypothyroidism include:

  • Weight gain
  • Lethargy
  • Cold intolerance
  • Dry coat and excessive shedding of hair
  • Very thin coat
  • Increased pigmentation of the skin
  • Failure to re-grow hair after clipping or shaving
  • A tragic expression because of thickening of the facial skin
  • Abnormal nerve function exhibited as non-painful lameness, dragging of the feet, lack of co-ordination and a head tilt
  • Loss of libido and infertility in intact males
  • Lack of heat periods, infertility, and abortion in females
  • Spots on the eyes
  • Dry eye because of inadequate tear production.
  • Anaemia

The thyroid glands are located in the neck either side of the trachea or windpipe. They are controlled by the body’s master gland, the pituitary gland, located at the base of the brain.


To confirm hypothyroidism we test blood to see if T4, the main thyroid hormone, is low. Unfortunately, dogs sick for some other reason or taking certain drugs like seizure medications, may have low levels too. Confirmation of hypothyroidism sometimes requires an additional test.

Hypothyroidism is treated daily with tablets containing a thyroid replacement hormone, thyroxine, for the rest of the dog’s life.

We check T4 levels again after a month of treatment to make sure we are giving the right dose. We test 4-6 hours after the morning dose. T4 levels are then checked every 6 months and the dose adjusted if necessary.

Overdosing produces signs of hyperthyroidism including hyperactivity, lack of sleep, weight loss, panting, nervousness, aggressive behaviour and an increase in water consumption. If any of these occur, please let us know immediately.

Cushing’s disease

What is Cushing’s Disease?

The adrenal glands overproduce cortisol in dogs with Cushing’s Disease. Cushing’s disease is also known as Hyperadrenocorticism.

What causes Cushing’s disease?

The three causes of Cushing’s Disease are:

  1. A pituitary gland tumour which overproduces the hormone that stimulates cortisol production in the adrenal glands. The size of the tumour and its malignancy varies widely. Signs of brain problems develop if the tumour is large, but this is unusual. Most dogs with this form of Cushing’s Disease live normal lives for many years as long as they take their medication and stay under close medical supervision.
  2. Excessive administration over long periods of time of synthetic cortisones like prednisolone, triamcinolone or dexamethasone causes Iatrogenic Cushing’s disease.
  3. An adrenal gland tumour is an uncommon cause of Cushing’s Disease. Surgical removal treats this form of the disease

How do I know if my dog has Cushing’s?

  • A marked increase in appetite
  • Increased water consumption and urination
  • Lethargy, panting and a poor hair coat
  • A pot-bellied or bloated abdomen

How is it diagnosed?

If we suspect Cushing’s Disease we run a blood test to check your dog’s general health.  An enzyme in the test called Alkaline Phosphatase (ALKP) is usually high in dogs with Cushings.

If ALKP is high then we do a Low Dose Dexamethasone test (LDDT) which will confirm or deny Cushings Disease.

To determine which type of Cushing’s disease your pet has, we ultrasound the adrenal glands and do an endogenous ACTH blood test.

Although some of these tests are expensive, they are necessary to allow us to accurately target the treatment.