HYPERTHERMIA AND LARYNGEAL PARALYSIS - HEAT STRESS

These articles are taken from the Affie lovers forum message boards after one of the members bitches suffered extreme heat stroke and from some of Sylvia's breed notes and may be very helpful to some of you

Given the weather conditions of this past w/e and Liz's very worrying experience with her bitch, this seems an opportune moment to reiterate on LARYNGEAL PARALYSIS. & associated HYPERTHERMIA in such conditions.

The following comments are taken from the excellent presentation given by ALASDAIR HOTSTEN- MOORE from Bristol Vet School on LP, this can be read in full by logging on to the NEWFOUNDLAND BREED CLUB WEBB SITE & under their HEALTH & LONGEVITY SECTION. It may take a bit of time for some in downloading & you will need adobe file reader (the file is 750K),in addition to the LP presentation ( a great pity a few more AFGHAN HOUND owners did NOT attend this lecture!! given in February 2005) there are some good papers on BLOAT.

http://www.thenewfoundlandclub.co.uk/health_&_longevity.htm

LP is the loss of movement of the VOCAL CORDS due to the loss of the NERVE SUPPLY to the MUSCLES of the LARYNX. The function of the Larynx is to control free air movement; cough; voice.
Difficulty in breathing (known as DYSPNOEA) results in panting; reluctance to exercise or a restricted ability. In some instances dogs will collapse (varying degrees) and ASPHYXIA can occur.

HYPERTHERMIA. & associated LP.
Hyperthermia is very feasible in any animal with a severe airway obstruction.
MANAGEMENT.....immediate veterinary treatment... which should consist of SEDATION, CONTROLLED COOLING viz environment; wet towels; fans etc AVOIDING DRAMATIC MEASURES viz hoses; packing in ice: cold enemas etc. OXYGEN THERAPY.
Cooling & calming will have an immediate affect.
When administrating oxygen therapy any stress factors must be avoided, viz the facial oxygen mask.

MANAGEMENT OF THE CHRONIC CASE OF LP following such a collapse.

Remember that if the condition is chronic, the dog may have de-compensated but may be stabilised and RETURNED TO THE CHRONIC STATE.
With the above medical treatments, cooling sedation etc, any emergency surgery ,either tie back or tracheotomy will rarely be required. The tie back surgical procedure can be performed asp when the dog has been stabilised.

LARYNGEAL PARALYSIS represents 90o/o of the common laryngeal disorders.
It is the commonest upper airway obstruction in the AFGHAN HOUND.
It occurs in the elderly dog, over 9 yrs of age.
It is a VERY COMMON CONDITION THAT IS FREQUENTLY MISSED BY OWNERS AND VETS ALIKE.
It's onset can be gradual and it is frequently assumed that the older dog is slowing up.
The classic stridor may NOT always be apparent at REST.
It severely inhibits lifestyle and ASPHYXIA can occasionally result from this condition.

SURGERY CAN BE HIGHLY SUCCESSFUL, even in the elderly animal. Various surgical procedures but the TIE BACK operation is the RECOMMENDED PROCEDURE AS A PRIMARY TREATMENT.
The surgery is successful in the RIGHT HANDS.
In the hands of the INEXPERIENCED, the surgery is dangerous and stressful.

If anyone has An elderly dog who is experiencing even minor episodes of LP or has been diagnosed with this condition, it is vital to ensure that the dog is constantly monitored in hot humid conditions ;I always remember Geoff Lane (Bristol Vet School) saying to me that it was in the SUMMER MONTHS that so many of these dogs were presented for surgery.

More on the effects of HEAT STRESS. I was browsing through some old magazines and veterinary papers and came across an article written in 1995 in an American journal with some useful comments concerning the effects of such extreme heat, more common outside the UK maybe, but many dogs are now "well established" into European travelling to both dog shows and holiday home destinations with their owners, and we have also been experiencing, some extreme hot and humid weather conditions so I thought I would share some of the detailed information . AWARENESS Is PARAMOUNT!

Quote  During hot summer months or in areas where a warm climate normally prevails, dogs that are exposed to high environmental temperatures, high humidity, inadequate ventilation and at times excessive exercise, may succumb to the effects of heat stress.

Most total body heat loss in man and animal occurs through radiation and conduction of heat from the body surfaces. Unlike man and other animals that have the ability to sweat freely, dogs have a relatively poor development of sweat glands, so less moisture evaporates in this way. Dogs lose their body heat primarily through breathing, by the vaporisation of moisture in expired air. The common response in the dog to rising body temperatures is an increase in the rate of respiration. Their breathing becomes faster but NOT deeper ( panting), which causes an increased water and carbon dioxide loss. Prolonged exposure to high atmospheric temperature and humidity or to improper ventilation overtaxes the dog's heat dissipating mechanism and will place an extra burden on the circulatory & respiratory systems.

There are 3 types of heat stress that may occur in dogs, prompt veterinary treatment is essential in all cases to save the animal from permanent systemic impairment or death.
Heat Stroke (sometimes termed Sunstroke) is the most common and often fatal syndrome in dogs .It develops rapidly. Physical symptoms include panting, a staring or anxious expression, failure to respond to command, hot dry skin, extremely high body temperature, rapid heartbeat & collapse, vomiting may also occur.

Heat Exhaustion or Heat prostration is another form of heatstroke which may occur in animals following prolonged exposure to intense heat and heavy exertion. Salt deficiency may serve as a predisposing cause. Heat Exhaustion develops less rapidly than heat stroke. It is characterised by fatigue, muscular weakness and circulatory collapse. Although this form is less common, it may occur as a complication of cardio-vascular or respiratory disease.

Heat cramps are painful muscular spasms caused primarily by the by the loss of considerable amounts of salt from the system and severe exertion in hot weather. Racing, Hunting dogs or any dog that is over exercised in such intense heat can be affected.

I will not go into the details of treatments, most of us SHOULD be aware of PREVENTATIVE measures when ever possible and the suitable FA measures to be taken in such circumstances but it is vital to seek professional assistance as soon as possible. The article goes on to say that in addition to the environmental circumstances, other factors may well influence a dog's susceptibility to heat stress. Our puppies are more vulnerable to external heat stress than adult dogs, likewise the elderly are also more susceptible as are the obese dogs. Layers of subcutaneous fat in an overweight dog can reduce the conduction and radiation of heat from the body surface. General health is a very important factor, any dog suffering a cardiac or respiratory condition may be stricken under conditions which would not be hazardous to a normal health dog so do be especially careful with those dogs already exhibiting the early signs of Laryngeal paralysis!. Also any dog with a previous history of a heat stroke is apt to be susceptible to a recurrence.

SYLVIA EVANS (AMSHURA)

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Updated 21-06-05