1 Introduction to Infectious Disease Management in Animal Shelters

       Kate F. Hurley1 and Lila Miller 2

       1 UC Davis Koret Shelter Medicine Program, UC Davis School of Veterinary Medicine, Davis, CA, USA

       2 American Society for the Prevention of Cruelty to Animals (ASPCA), New York, NY, USA

1.1 Why This Book?

      Though many excellent veterinary texts on infectious disease have been published over the years, the first edition of this book was published in 2009 to fill a gap in understanding the specific challenges and solutions regarding infectious disease management in shelters. The risks in this context are abundant. Animals entering shelters are often unvaccinated, suffering from parasite infestation, poor nutrition and a variety of other stressors. Shelters house lost, unwanted and abused animals spanning every life stage, from neonates to geriatric pets, each with their own unique risks and requirements. Limited resources and outdated facilities, still found at many shelters, increase the difficulty of keeping these vulnerable populations healthy.

      At the same time, the potential rewards of successful disease management in shelters are even greater than the challenges. Infectious disease in shelters has historically been a leading cause for euthanasia. But, in addition to being literally lifesaving, successfully treating individual animals, managing outbreaks, and most especially, preventing disease increases animals’ welfare. Prevention of illness can also conserve precious resources and free up space in the shelter that would otherwise be occupied by sick animals. In turn, the improved public confidence that a healthy population tends to generate can lead to greater support of the shelter, higher adoption rates, and an increased capacity to invest in programs to decrease shelter admission and keep pets healthy and safe with their families.

      1.1.1 Fundamentals of Disease Control in Shelters

      Though some unique considerations exist for shelters, the fundamentals of disease management rest on a familiar foundation. In veterinary medicine, it is customary to think about the “disease triad” that describes the interaction of pathogen, host and environment in determining whether disease occurs. Introduction of pathogens into a shelter is virtually inevitable; therefore, efforts focus on supporting animals' immunity and limiting disease spread within the environment.

This text will provide strategies to accomplish each of these goals with respect to specific pathogens commonly encountered in shelters, as well as general information on methods to support immunity and limit environmental spread (e.g. see Chapter 2 on Wellness, Chapter 9 on Canine and Feline Vaccinations and Immunology, Chapter 8 on Sanitation and Chapter 6 on Outbreak Management). The reader will find information that reflects the ways in which shelter‐specific considerations result in recommendations that vary from the approach that might be recommended in another context.

      For instance, maternally derived antibodies (MDA) in juvenile animals have both good and bad consequences: they provide initial protection against disease but also potentially block vaccines. Initial levels of MDA will determine the age at which vaccines can overcome this interference, and this information has historically guided vaccine recommendations for pet puppies and kittens born to vaccinated dams. However, it is now known that many juvenile animals entering shelters were either born to unvaccinated dams and therefore received no MDA (and therefore no potential for MDA interference); or were born to mothers who survived field strain infection and may have transmitted high levels of MDA (Lechner et al. 2010). This means vaccines may be effective either earlier or later in comparison to offspring of a vaccinated dam with an intermediate level of MDA to transmit. This, coupled with the higher disease exposure risk common to shelters, leads to the recommendation to start vaccination earlier and continue longer for puppies and kittens in a shelter environment.

      Another example can be found in the treatment recommendations for dermatophytosis. Often a self‐limiting disease of little consequence in privately owned pets, this zoonotic and environmentally persistent (and resistant) pathogen has historically been the cause of euthanasia in many shelters. However, protocols that limit environmental contamination through effective topical, as well as systemic treatment, have been developed to allow this condition to be managed successfully at an increasing number of shelters (Newbury et al. 2011).

      1.1.2 The Production Medicine Model

      For all its benefits, infectious disease control is only one goal of a successful shelter medical program. The production medicine model, developed in the context of commercial animal husbandry enterprises, proves surprisingly applicable here. The successful livestock veterinarian understands their role extends beyond treatment or even prevention of disease. Rather, they provide guidance to help the production system reach a variety of goals, which may include such things as providing a healthy, safe food product, ensuring that the enterprise is financially sustainable, providing good welfare and maintaining compliance with relevant regulations. None of these goals may be reached at the expense of another.

      Similarly, the shelter practitioner must approach the task