Respiratory and General Health of Dairy Cows associated with Wildfires (a synthesis)
Jos P Noordhuizen*
Veterinarian, formerly professor at the University of Charles Sturt, Australia, and Universities of Utrecht and Wageningen, The Netherlands
Submission: May 08, 2023; Published: May 23, 2023
*Corresponding author: Jos P Noordhuizen, Veterinarian, formerly professor at the University of Charles Sturt, Australia, and Universities of Utrecht and Wageningen, The Netherlands. Email: [email protected]
How to cite this article: Jos P Noordhuizen. Respiratory and General Health of Dairy Cows associated with Wildfires (a synthesis). Dairy and Vet Sci J. 2023; 15(4): 555920.DOI: 10.19080/JDVS.2023.15.555920
The respiratory health of dairy cows has a great importance for their general health status and their productivity. Respiratory health is impacted by many intrinsic factors as well as environmental factors. Poor barn climatic conditions and failing management, as well as heat stress conditions are examples of situations where-in the basic respiratory health is not optimal. Moreover, wildfires lead to situations where the basic respiratory health is further impacted. Wildfires occur every year and worldwide. The most important risk factors are the heat of the fire itself, the smoke of the fires which may travel large distances, the fine particles in the smoke and the chemical components in the smoke. Some particles are so small that they enter deeply into the lungs of the cows and cause damage there. In this paper, the basic respiratory health of cows is addressed, as well as the risk factors in housing and management contributing to this basic respiratory health, and the signs of a disturbed respiratory health associated with wildfires. If indicated, comparisons are made with the situation of human beings.
Good basic respiratory health (BRH) is important for a good general health status and good performance, especially in high yielding cows. These cows are quite comparable to top athletes [1-5]. A disturbed BRH has a negative effect because the oxygen exchange in the lungs is disturbed, while the immune responsiveness is reduced . The BRH is influenced by factors such as the general health status of the cows, the management quality of the farmer, for example regarding the barn climate, the nutrition, and his management of heat stress , the quality of the air (pollen, particles, chemical components, gases related to wildfires).
The effects of heat stress and wildfires occur in the same season
Cows respire by their nose and eat their feed with their head low. When there are obstructions in their respiratory system, their respiration is hampered. Poor barn climatic conditions and poor air quality outside will lead to a situation where cows can no longer get rid of dust, particles, and micro-organisms from their respiratory system in a physiological way [3,4]. A BRH already disturbed will be affected even more when wildfires occur. The goals of this paper are to present (1) the characteristics of a BRH and the parameters to evaluate the BRH, (2) the signs of a disturbed respiratory function, and (3) discuss the various effects of wildfires on the respiratory health in dairy cows. Finally, management measures are proposed to limit the forenamed effects.
The basic respiratory health of dairy cows, and the air quality outside
BRH is defined as the physiological function of the body to exchange oxygen from the air to the lungs and blood circulation. This exchange function is influenced by genetic make-up of the cow, the general health status, the anatomical conformation, and different environmental factors such as farm management quality, and air quality. The heart frequency of a cow in rest is between 15 and 35 bpm, depending on breed, the level of metabolism and level of milk yield. When this frequency rises dramatically, there is a true problem. Air Quality is important. This quality concerns, among others, the level of air pollution, de concentration of pollen, fungi spores, chemical pollution, and fine particles . The  has
developed and Air Quality Index (AQI) which is a parameter for
air quality. This AQI considers various factors named in Figure 1.
Furthermore, EPA has a large international network of institutions
around the world from which data about air quality are sent to EPA
and by which the AQI can be calculated per region . In Figure 2
is presented a so-called ‘easy to read’ infographic about AQI. It is
generally accepted that, at an AQI of 300, man has an increased
risk of respiratory and possibly other problems. Dairy cattle
are less sensitive than man and their threshold value is rather
around an AQI of 350 (in comparison: a sport horse would have
that threshold value around 300 too). The individual, biological
variation among men and among animals causes the fact that even
at lower AQI there always be individuals who are more sensitive
to the problems than others (see the triangle in Figure 2 for those
individuals). Hence, the AQI is an indication, not an absolute value.
As mentioned earlier, there are also other factors impacting
respiratory health. These are the factors of housing the cows
and the quality of farm management, addressing quality of feed,
of drinking water, of hygiene . When several of these factors
together have a negative impact, the respiratory health will be
impaired, and the cows are more sensitive to heat stress, social
stress, and effects of wildfires . Table 1 presents an overview
of different parameters for checking the BRH in cows. When most
of the parameters deviate from the target value, problems in barn
climatic conditions and/or farm management will be present [1-
4]. In Table 2 are listed the signs of disturbed basic respiratory
health. These signs may also be observed in cows suffering from
pain, in cows under heat stress conditions, social stress and or
stress caused by wildfires. The parameters in Table 1 look a lot
like the various factors causing respiratory disorders in man.
However, in man much more factors are known, which are not applicable in dairy cows. Examples are tobacco use, chronic heart and/or pulmonary problems, cancer, body weight (obese), social
status, allergies, educational level . The Signs Listed in Table 2
are Comparable to those Observed in Man.
Components in the air originate from wildfires and have effects on respiratory health in dairy cows
During wildfires many products are freed in the air, namely
in the smoke. This smoke may be extended over large distances
. The composition of the smoke depends on the different types
of wood, vegetation, plastics, construction material and other
combustible material being burned . All materials named
produce a range of different (chemical) components when they
burn [5,11]. The greatest threat for the respiratory health of
dairy cows in prairies (and men) comes from fine and ultra-fine
particles in the smoke . Specifically, the particles P10micron and
P5micron) are dangerous. The P5micron enters deeply into the lungs .
To get an idea about the size of the fine particles, a human hair has
a diameter of 60 micron. Table 3 presents an overview of different risk conditions for respiratory and general health problems in dairy cows (and man), as represented by components in smoke.
The biggest problems are caused by droplets of liquid fine particles
and solid fine particles in smoke. The particles P2,5micron (and even
smaller ones) enter most deeply into the lungs and cause much
damage there in tissue and cells. Note that ashes and soot in the
smoke may cause irritation of skin, nose, eyes, throat, which is
often accompanied by bleeding and frequent coughing.
Table 4 presents the effects of smoke from wildfire on dairy
cows. These effects are comparable to those listed in Table 2 for
disturbed basic respiratory health (BRH). The smoke and its
components are, hence, the greatest risk factors for disturbed
respiratory health in dairy cows (and man). In all cases, the
welfare of the cows is severely impacted. Decisive factors in
wildfires which lead to a severely polluted air and a poor health
status are the duration of exposition, the volume of air (smoke and
soot) inhaled, the level of the individual health status (vaccination
status, disease history, age) and the concentration of toxic
components in the air (that is: smoke) . Inhalation of smoke can
rapidly cause hypoxia of the brains and the lungs .
The prognosis for a dairy herd or cow depends first on the
possibility and rapidity of evacuating that herd far away from a
wildfire location to a healthy spot (or prairie) out of the wind and
smoke. A universal protocol cannot be given here because it must
be tailor-made to an individual farm. What about individual dairy
cows? High yielding cows are more sensitive to wildfire effects of
smoke and components than low producing cows. But both will
be affected. Depending on duration of exposition and severity of a
wildfire, especially the smoke and its components, and the general
state of resistance and sensitivity of the animal, the prognosis of a
potential recovery will vary . For example, after light exposure,
the recovery of a horse may take two to four weeks; for a dairy
cow it might be comparable. But again, it depends on exposure
and duration. If a chronic problem has been established in the
meantime (for example after a severe and longtime exposure to
fine particles entering deeply into the lungs), a recovery -if anymay
take more than 2 months. Some cows develop chronic asthma
and will undoubtedly be lost. Sometimes cows cannot be saved at
all and die; other times cows show signs only one or two days after
exposure to a wildfire of short duration.
Note that the halftime life of fine particles entering deeply into
the lungs is about 90 days [5,11]. There is, hence, a residual effect.
The effects of an immune depression become manifest much later.
Effects of exposure on the long term have not been studied in dairy
cows or have not been reported. Conclusion is that the long-term
outcome is not predictable at all. As a result, it will not be easy for
a veterinarian to speak about the prognosis for a cow affected by
forest fire or its components.
i. Despite the biological differences between dairy cows
and man, still comparisons can be made as is shown in the text.
One big difference between species is that several studies on the
sensitivity of man and about the effects of wildfires (smoke, gases,
fine particles, chemical components, soot) on man have been
reported in literature. Such studies on dairy cattle are unknown, or
never reported. Another difference between man and dairy cows
is that treatments are proposed for man but not for dairy cows,
most probably because of the costs and the applicability. Man may
escape from forest fire, dairy herds mostly cannot. An exception
in treatment is maybe the rapid treatment called ‘re-oxygenation’
of the genetically most valuable high yielding dairy cows in the
herd. In the context of a Biosecurity Plan on a dairy farm, it would
be advisable to develop a Protocol ‘Wildfire Actions & Prevention’,
not in the least because fires are not limited to forest fires but
may also occur inside buildings. The purpose of such a protocol
is the awareness of prevention, for example an Action Plan for
evacuation as part of a Fire Actions & Prevention Plan. The latter
should be best developed together with the local fire brigade. It
is out of the scope of this paper to elaborate these protocols here.