Throughout my research on the transport of animals in the nineteenth century, I have been struck again and again by the horrifying death rates that occurred on many of the animal-carrying ships of the time. The reason for this, in the case of birds, is quite simple—they moulted in the heat of the tropics and then caught cold and died as the ship moved south into cooler latitudes. Ships that approached New Zealand in summer had a higher success rate with shipments of birds, and, as Richard Bills found out on the Waimate, the birds had to be kept as cool as possible while crossing equatorial regions—iron-sided ships could be fatal.
With mammals the problem was more complex. It appears that the deaths may have been caused by a condition known now as 'shipping fever'. The bacteria which causes this condition is Pasteurella—a very common group found routinely in the nasal and digestive tracts of cattle, horses, pigs and most other mammals. If the animal becomes run down or fatigued or frightened, or is living in overcrowded conditions with poor ventilation or poor feeding, then the body's resistance systems, which are normally well able to cope with the Pasteurella bacteria, fall down on the job, and the animal sickens.
The disease that then appears is called pasteurellosis, and varies in its symptoms. It may appear as a swelling and bleeding of the liver and kidneys, or the head, neck and throat may swell, with the production of a lot of strangling fluid. The lymph glands may swell acutely, and there may be bleeding of the small intestine and colon. In other cases the disease looks like acute pneumonia, with the fluid discharge and bleeding that one associates with this disease. The animals get very sick and usually die very quickly, or may arrive miserable and ill, and die some time after landing. The disease is not normally transferred from one animal to another, although in special circumstances, such as long periods of upset and overcrowded conditions, this will happen.
The amazing thing is that pasteurellosis is not just found in cases of animals being carried long distances in the past under nervewracking conditions, but is a condition that is still very common today. Cattle that, in countries such as North America, are transported long distances for sales or fattening, die just as distressingly as their ancestors did in the wooden ships that sailed across the world. When one thinks of it, the same conditions apply—stress, strain and overcrowding. Because shipping fever is so common, attempts have been made to develop a serum or vaccine to combat it. These efforts have not been very successful, probably because the Pasteurella group of bacteria is such a large one. Dr Soltys, of Canada, a country which has a high incidence of pasteurellosis, says that when a group of eight horses was infected with Pasteurella by accident during a routine vaccination, injections of anti-serum, though immediate, failed to save even one of the horses.
Can man get pasteurellosis? He can, if he is bitten or scratched by an infected animal. When one reads accounts of how animals died because their keeper was ill in his bunk, one wonders if he may have had the disease that was killing them. How can shipping fever be prevented? Care and attention is the answer, with stock being well fed, kept quiet, tranquillised if necessary, and maintained in dry sheltered quarters away from disturbances. This list of conditions emphasises the skill and organisation that men such as Cook, Petre, Bills and Donne must have applied to be so successful in transporting animals halfway across the globe.
Perhaps the most interesting feature of the disease is that it is not a disease of New Zealand. In such a small country the animals are not carried the long distances that are associated with the condition. The days of carrying animals for long periods are over, although it is interesting to note that with the modern development of carrying stock from New Zealand to other countries by air, incidents of animals developing a type of stress-related 'pneumonia' are being recorded.