March 1, 2016

Farm working Dogs in New Zealand. 6. Common Health Problems

By Dr Clive Dalton

Internal parasites

Hook worm (Uncinaria)
About 50% of dogs are infected with hookworm.  Eggs develop in the soil and larvae can burrow through the animal's skin.  They mature inside the dog and are passed out to complete the cycle.   Some dogs have developed a high resistance to hookworm infection and may only show lack of energy when working.

*  Unthriftiness.
*  Anaemia.
*  Coma and death. 
*  Don't house dogs on dirt floors.
*  Steam-clean kennels and move to clean ground.
*  Keep dogs away from infected areas.
*  Consult your vet for a drenching programme.
 Roundworms  (Toxocara canis)
The most common worm in dogs.  Pups get infected by migrating larvae in the bitch's tissue.  Many of them will not show signs of infection but the worms will be there.

*  Pot belly.
*  Intermittent diarrhoea.
*  Nervousness.
*  Death in severe cases. 
*  Contact vet for appropriate treatment.
*  Treat pups at 2, 4, and 6 weeks of age.
*  Keep a clean kennel.
*  Keep a clean food storage area.
*  Maintain good hygiene with a whelping bitch.
*  Keep young children away from pups in dirty conditions.
Whipworm (Trichuris)
Causes inflammation of the caecum. 
*  Weight loss.
*  Diarrhoea.
*  Get worse as worm burden increases. 
*  Check with vet for correct treatment.
*  Regular dosing every 6 months.
Fleaworm (Didylidium caninum)
This dog tapeworm grows inside the dog, and the eggs pass out in the faeces.  The flea then eats the eggs which grow into cysts inside the flea.  The dog then eats the flea to complete the cycle.

*  General unthrift. 
*  Check with the vet for a correct diagnosis.
*  Treat the dog by breaking the cycle.
*  Drench the dog every 3 weeks.
*  Treat for fleas.

 Hydatids tapeworms 
There are three tapeworms which come under the common name of "hydatids" tapeworms so it can be confusing.  It's important to know their differences.

 True hydatids  (Echinococcus granulosus)
The main concern here is for human health, and thankfully because of past programmes the incidence of hydatids is very low.  Note though that it is still there and this parasite must be taken seriously.

If dogs eat the untreated offal of sheep, goats, pigs, and cattle, they can ingest cysts which are full of immature tapeworms.  On bursting they grow into small tape worms 3-6mm long in the small intestine of the dog and have little effect on its health. 

When these tapeworms mature their end sections drop off and are full of highly resistant eggs which can live on pasture for several months.  When eaten by an intermediate host (sheep, cow, pig, goat or human), these eggs hatch and develop into slow-growing cysts, usually in the liver and lungs.

The cysts generally don't affect livestock but in humans can grow to 50mm across and can be life threatening.  If a cyst burst inside a person, then the risk of further infection is very high and recovery low.  They face a lifetime of regular surgery to remove them.

 False hydatids (Taenia hydatigena)
This tapeworm lives in the dog and can grow up to 5m long.  The eggs pass out the dog on to pasture and if eaten by sheep, goats, cattle, pigs and deer hatch into larvae which during their migration though the body can damage the liver.  They end up in the abdominal cavity where a cyst up to 10mm in diameter develops..

 Sheep measles (Taenia ovis)
This tapeworm only moves between sheep and dogs.  Human health is not involved.  Although the tapeworm can grow to 1m long inside the dog, it doesn't seem to affect its health.  It has a typical tapeworm life cycle from inside the dog, picked up by grazing sheep as the eggs can last a long time pasture. 

The intermediate stage inside the sheep is where cysts appear in the heart muscle and diaphragm.  Infected carcasses have to be trimmed or rejected for export.  The cysts are hard creamy-white nodules about 5mm across and appear in .  In bad cases they will be all through the big muscles too, looking like an attack of measles.

They are no risk to humans but can put customers off buying lamb for ever.

Prevention of all "hydatids" in dogs
*  Register all dogs.
*  Treat them regularly according to veterinary advice.
*  Prevent all dogs from having contact with dead animals.
*  Don't feed any offal from any farm animal to a dog.  Offal is maybe cheap dog feed             but the risks of infection are too great.
*  Burn or bury all offal.
*  If you feed sheep or goat meat to dogs, either heat it to 72 degrees Celcius for at least an hour, or freeze it at minus 10 degrees C for at least 7 days.
*  Provide dog-proof enclosures for killing dog meat.
*  Provide secure housing for dogs.
External parasites 
There is an old saying that "fleas are good for dogs, they remind them that they're dogs!"  This is a lie.  Fleas don't breed on dogs, they breed in the dirt and debris of the kennel and surrounding area, where larvae develop into adult fleas.  These then invade the dog and cause great irritation.  Constant scratching can damage the skin and allow secondary problems such as anaemia and loss of condition to arise.

Fleas breed faster in warmer weather - so be on guard in summer and autumn.  Modern flea collars work well with protection for up to 4 months.  It's a good idea to clean up the kennels with insecticide too to reduce the population.  Follow the label with all insecticides.

These are common on dogs but don't show much effect.  A really heavy infection will cause anaemia.  Lice only live on the dog so there is no need to treat the kennel area.  Kill the lice on the dog with some of the modern treatments (see your veterinarian) and that will fix the problem.

 Cattle tick (Haemophysalis longicornis)
This is the only tick found in NZ and can be a nuisance on cattle and deer if present in large numbers.  Dogs will easily pick them up during work.  The tick sucks blood, becomes engorged and then drops off.  It's not until the animal is heavily infested that it may be of concern.

Don't pull the ticks off the dog as the head remains in the skin and can cause infection.  They can be removed by kerosene but it's best to treat the dog with a correct insecticide.  Check with your vet.

 Ear mites (Otodectes)
Causes irritation in the dog's ears and may lead to secondary infections by bacteria and fungi.  Consult your vet if your dog is scratching or shaking its ears which can be very sensitive.

 Mange mites
Demodex and Sarcoptes mites are the cause of mange in dogs.  If the dog is scratching a lot, is losing hair and there are secondary skin infections present, then check if mites or consult your vet.  These mites burrow down into the skin and there's a chance that they can infect humans.

So don't delay with treatment, as bad infections can take a long time to eradicate.  DO NOT put the dogs in the sheep swim dip or shower, or use any sheep pour-on treatment.  This could kill the dog.
Virus diseases 
This can be a very nasty disease in dogs and very distressing for owners as they see their dogs taking fits.  Signs include:

*  Fever.
*  Depression and loss of appetite.
*  Running nose and eyes.
*  Coughing.
*  Scouring.
*  Fits, yelping and twitching.

It's caused by a virus, usually widespread among dogs, and can be picked up from contaminated objects like clothing.  It spreads from dog to dog by moisture from eyes and nose.

Incubation is about 10 days during which the virus affects many organs such as the gut, lungs and brain.  Many dogs (about 50%) develop sufficient antibodies in a couple of weeks to control the disease and recover well.

Dogs with no antibody resistance will die.  Bad cases may recover but the dog may have impaired eyesight for the rest of its days.  It is essential to vaccinate when the dog is 6-8 weeks, 12 weeks and 16 weeks of age.  This is usually combined with parvo vaccination.  Then an annual booster may be needed if the dog isn't in contact with other dogs that challenges its immunity.  Check with your vet for details.
A really distressing disease for both dog and owner.  The virus is excreted in the faeces of infected or carrier dogs and can survive in the environment for some days.  Incubation takes from 1-5 days but it's not certain how it spreads.  These pups become depressed and die.

One form of parvo (Cardiac) affects the heart muscle of pups under 4 months old, and the other (Enteric) is seen in dogs of all ages.  These dogs vomit and have a severe foul-smelling diarrhoea.  Blood may show in the faeces.  The dog will be depressed and run a temperature.

Vaccination against parvo is essential for all pups and is usually tied in with distemper protection.  Consult your vet for details.
Infectious hepatitis
Not very common but can be devastating. 
Signs are: 
*  Vomiting and diarrhoea.
*  Fever
*  Thirst
*  Listless
*  Discharge from eyes and nose.
*  Red mucous membranes.

The virus is spread in all the dog's excretions and attacks the liver and other vital organs.  Prevention is by vaccinating young pups and is tied in with distemper and parvo protection.  Consult your vet for directions.

Other viruses
There are many other viruses that can affect dogs and appear as epidemics in districts after introduction by a carrier dog.  So it's a good idea to isolate a new dog for a while to make sure it's not a carrier.  Check what vaccinations a newly purchase dog has had, and discuss vaccination with your vet against these potential problems

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