More factors influencing infectious diseases

By Dr Steve Surujbally

(Continued)

6. Colour

We had said last week that certain breeds, eg the Doberman or the Rottweiler, be-cause of their predominantly dark-coloured hair, were more vulnerable to persisting ectoparasitic infection – not lastly because it is difficult to see the fleas/ticks/lice on a dark background. Treatment may therefore begin too late.

On the other hand, animals with predominant white colour tend to succumb to solar radiation more than pigmented animals. You may have noticed that there are very few white cattle grazing alongside our rural roads, and of those, their hides have multiple lesions and crusts and eczema-like sores.

We know that Hereford type cattle (the big beef cattle with the white faces) are more susceptible to the disease called Pink Eye which could result in blindness. White dogs and horses in the tropics tend to be more affected by light sensitisation.

7. Heredity

Well, the inheritance factor is always important. Last week, we spoke about the disease problems associated with the breed, and above, we mentioned colour. These are all factors that deal with heredity. But I am specifically speaking about developmental abnormalities which arise as a result of problematic genes.

The cleft lip/palate, the inability of the testicles to develop, monorchidism (only one testicle), hernias, and so on, are all examples of genetic disarray – often associated with inbreeding. ( should also mention that the level of resistance to a particular disease may also be determined by heredity. In fact, one could manipulate the genetic factors in such a way as to make animals more resistant to specific diseases.)

8. Diet

I am convinced that malnutrition is one of the greatest factors influencing disease exhibition. We feed puppies as if they were adult dogs, and we feed elderly animals as if they were young, growing dogs. And, often, we just don’t feed our pets adequately – with a balanced protein /fat/carbohydrate ration.

At a later date, we will deal in detail with dietetics, especially relative to the young, adult and elderly pet.

We will then see how the lack of, for example, vitamins/minerals could influence the emergence of skin problems and disease susceptibility.

We tend to take the feeding regime for granted. That would be very wrong. And as I mentioned pretty early in the series, you should not be choosing a pet which you cannot afford to feed optimally.

9. Environment

This is an all inclusive term and, nowadays, what with all the talk on sustainability and longevity of our planet, it has become an overworked term. But within the context of our pets, I am referring to the immediate surroundings in which the sanitation/hygiene aspects must be given maximum consideration.

Veterinarians are so often frustrated when they get rid of a bad skin disease on one day, only to see it return a month later, because the re-infection came from an unsanitised environment.

10. Anomaly/inherent
susceptibility

I mention this tongue-in-cheek, simply because I have no explanation for the observed fact that on occasion, only one or two puppies of a litter will succumb to a disease. They all are living under the same dietary and management conditions, yet, two get sick and five don’t.

What is interesting is that it is not always the runt that falls prey to the disease. Sometimes it is the biggest, healthiest looking pup of the litter. Right now, my neighbour has a litter in which the two healthiest puppies are afflicted with umbilical hernias. As an aside, I might mention that this phenomenon is also seen in humans. Measles or Red Eye might invade the ghetto, yet half the children don’t exhibit the disease.

11. Previous disease

This may confer a desirable level of immunity against a peculiar disease. Conversely, it may make the animal more vulnerable to repeated attacks of the same disease or new diseases.

A good example would be found in respiratory disorders. If, for example, pneumonia weakens the lungs, the animal is more likely to have lung related diseases in the future. Generally speaking, non-specific diseases predispose to further attacks by the same or new infections, while specific infections usually give an immunity against further ailment from the same disease.

Next week we’ll get into the issue of immunity in more detail. It is a concept that we must understand before we continue with the theme of infectious diseases.