Heat Stress

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Alpacas are native to a climate which can fluctuate between extremes of temperature in excess of 30ºC during the day to below freezing at night, combined with a very low humidity, making them extremely resilient in regards to heat and cold, but not so tolerant to heat combined with high humidity, or cold combined with high precipitation (snow). Now transplanted from their native South America they are often expected to withstand temperature conditions which are totally different to those of their homeland.

Heat stress is an often over-looked problem in alpacas In New Zealand, Australia, and parts of North America, but can cause serious problems, including dehydration, reproductive problems (abortion, premature birth, cessation of lactation, and male infertility) and poor growth, to name a few.  Prevention is not hard if you provide adequate shade and water, and shear your alpacas before summer heat kicks in!

An Australian study has shown that alpacas are more subject to heat stress than is generally acknowledged. Two groups of alpacas were kept in identical, mid-summer conditions, one group was shorn, and the other carried a full fleece. Behaviours (drinking habits, signs of physical distress) were observed, and in addition, internal temperatures were monitored. It was noted that neither group showed any discernable difference in behaviour or symptoms of distress, however, the internal temperature checks showed the fully fleeced group had temperatures up to 5 °C higher than those in the shorn group.

Conditions likely to give rise to heat stress can be monitored by summing (adding together) the ambient temperature (in Fahrenheit) with the humidity (percentage value). If the total of these two figures equals 160 or more, conditions exist for heat stress to develop in vulnerable alpacas. eg. if the ambient temperature is 80ºF, and the humidity is 80%, the total value is 160, and becoming dangerous for some individuals. This is known as the heatstress index calculation, or HIS=Temperature + humidity. Obviously in NZ, you will need to convert from Celsius to Fahrenheit to use HSI. (We have a link to a conversion chart on our Links page).

Factors other than temperature/humidity may combine to make any individual alpaca more susceptible to heat stress. These factors included transportation, rehoming or regrouping, rapid climate change (such as occurs during export/import), illness, advanced pregnancy, overweight, (see body scoring) very old or very young alpaca, and excessive parasitism (see Worming in our Health & Welfare section).

Visible and/or clinical signs of heat stress (and remember alpacas can suffer heat stress without visible symptoms) include panting, depression, anorexia, and increased heart rate, temperature and/or breathing. As the condition progresses, drooling can occur, trembling, weakness, lying down (and trying to expose the belly), sweating, shock and disorientation, muscle damage, and ultimately, death.

New born cria are particularly vulnerable to heat stress as it can take 2-3 days after birth before the cria’s internal temperature regulators become fully functional. New mothers particularly are not always sensible about taking their cria into shade. If you see a newborn cria lying limp and unresponsive in a paddock on a hot sunny day, the chances are it has heat stress, and you need to take immediate action to save it. See instructions for treatment of heat stress below.

Prevention of heat stress:

  • Shearing – this should occur before the end of December (Southern hemisphere) or beginning June (Northern hemisphere). Not shearing is not an option!
  • Shade – It is vital that alpacas be provided with summer shade! Your alpacas will readily rest in the shade of large trees, but sufficient shade must be available for all animals to shelter.
  • Water – Clean fresh water should be available at all times. In periods of intense heat/drought, place water in shade and replace at least twice daily. Sun-warmed water will not cool your alpaca!
  • Wading – Many alpacas will seek out pools, puddles and streams to keep cool.  A great way to cool down, though may lead to wool rot. If you don’t have standing or running water available, try using a garden sprinkler.
  • Feeding – Pasture feeding is best, but not if it forces your alpacas into the sun. Give good quality hay in a shaded area.
  • Electrolytes – added to your water have a protective effect by supplying mineral and vitamin losses that occur during sweating and breathing.  Additional vitamin E, selenium, zinc and copper are of particular interest in combating heat stress. Clean water buckets daily as bacteria grows quickly in these conditions.
  • Pregnancy- Avoid pregnancies that include gestation/birth at the hottest time of year – late spring and late autumn births are best in NZ. Congenital birth defects are 10% more likely to occur in cria born to females that have experienced days of elevated heat in the first trimester of pregnancy. Abortion and premature birth are other side effects of heat stress in pregnant alpacas.
  • Ventilation – a good breeze is worth gold! If you shade your animals inside a barn, then you should install fans that blow across at floor level on different angles.
  • Bedding – if your alpacas are kept inside, do not use straw for bedding. Use moist sand instead, or even plain concrete – this is hard and uncomfortable but cool and easy to clean.
  • Monitoring – observation saves lives! Watch your animals and learn their habits. If they spend a lot of time eating, standing, walking and being active, they are probably healthy and happy. If they lie around most of the day, they may be suffering heat stress (or some other illness). Watch stud males – if the scrotum starts to increase in size, do something immediately or he may end up infertile.

Treatment of heat stress

Speed of commencing treatment is imperative. In severe cases (or even if you are unsure) call your vet immediately – but don’t wait for him/her to arrive before initiating action.

  • Water – cool down as fast as possible by applying cold water to legs, belly, armpits and groin. If using a hose, ensure cold water is flowing ( stationery water in a hose lying in the sun can be quite hot!).
  • Drinking Water – offer cool water to drink. If your alpaca won’t drink, you can administer water as a drench, but can only be done if patient will tolerate it. The amount of water given must be moderate eg 1 – 3 litres (1 quart to 1 gallon) for an adult.
  • Breeze – turn on fans if nature won’t oblige
  • Ice – ice packs (frozen peas will do) in the armpits and groin
  • Cold water enemas – effective but can hamper the ability to monitor core body temperature. Best administered by your vet.
  • Newborn cria – give a plasma infusion as soon as possible, this will do more to save your cria than anything else