Search

This chapter discusses the bumps on the vaccine road. The challenge to produce effective and safe vaccines for the currently prevalent infectious diseases of humans and animals has become increasingly difficult. In veterinary medicine, evidence implicating vaccines in triggering immune-mediated and other chronic disorders (vaccinosis) is growing. Although some of these problems have been traced to contaminated or poorly attenuated batches of vaccine that revert to virulence, others apparently reflect the host's genetic predisposition to react adversely on receiving the monovalent or polyvalent products given routinely to animals. The onset of adverse effects of vaccination can be expressed as an immediate hypersensitivity or anaphylactic reaction; an acute event occurring 24–72 hours afterwards, or 10–28 days later in a delayed-type immunologic response, or even later as seen with mortality from high-titered measles vaccine in infants, canine distemper antibodies in joint diseases of dogs, and feline injection-site fibrosarcomas. These adverse vaccine reactions typically include fever, stiffness, sore joints and abdominal tenderness, susceptibility to infections, neurologic disorders and encephalitis, collapse with autoagglutinated red blood cells and icterus (autoimmune hemolytic anemia [AIHA]), or generalized petechiae and ecchymotic hemorrhages (immune-mediated thrombocytopenia [ITP]).

Publisher Summary This chapter discusses estimating disease prevalence with health surveys and genetic screening. It is important that the top-producing sires and foundation bitches of a breed be screened for conditions prevalent in that breed or in dogs generally, because they represent the major nucleus of genetic material for the current and future decades. Despite the proven benefits of this approach and intensive educational efforts, some breeders choose not to participate. Veterinarians and scientists who provide testing and genetic counseling services should understand in dealing with the concerns and sensitivities of these individuals. Attempts to pressure people into participation can be counterproductive to the overall goals of the program. Success depends upon an honest, voluntary commitment to the principles and ethics of breeding better companion animals. One can even question the appropriateness of propagating purebreds if a significant proportion of a particular breed suffers from one or more clinically expressed genetic traits, especially when several million unwanted or stray animals are killed annually in pounds or shelters.

We have developed an ELISA specific for canine von Willebrand factor antigen (vWF:Ag) that also strongly reacts with the VWF:Ag of humans and many other vertebrates. This assay was designed to avoid the use of immunoreagents of human origin, however, commercially available antibodies to human vWF:Ag may also be used. von Willebrand factor (vWF) was quantitated using a modified double-sandwich ELISA with polyclonal antibodies specific for canine vWF:Ag. The assay was as sensitive for measuring canine vWF:Ag as previously published immuno-radiometric assays and the most sensitive ELISA for human vWF:Ag. Employing commercially available antibodies to human vWF:Ag in the same double-sandwich configuration, the lower limit of detection for human vWF:Ag was 4.8 x 10(-6) units/ml, lower by a factor of ten than previously reported ELISAs. In addition, a wide range of vWF:Ag levels can be determined with just a single plasma dilution. The assay readily distinguishes type III von Willebrand disease from other types of von Willebrand disease having very low levels of vWF. This vWF ELISA can be used to evaluate large numbers of plasma samples simultaneously and is therefore well-suited for large-scale screening programs.

SummaryTotal progressive antithrombin activity was significantly below normal in dogs with DIC and in aged Syrian hamsters with atrial thrombosis and consumption co-agulopathy. It was normal in hea...

SummaryCoagulation and fibrinolysis were studied in a colony of aged Syrian hamsters with spontaneous atrial thrombosis, and the results are consistent with concomitant consumption coagulopathy. In comparison to age- and sex-matched hamsters from the same colony, those with atrial thrombi had significantly prolonged prothrombin and partial thromboplastin times, reduced levels of factors II, VII, VIII and X activities and plasminogen; and concentrations of fibrinogen-fibrin split products in excess of 80 μg/ml. Hematocrits of the thrombosed animals were significantly decreased, total plasma proteins were increased, leukocyte counts were within normal limits, and platelet counts were about half those of the controls. Thrombosed hamsters had significantly reduced plasma albumin content, increased γ1-, β-, and γ-globulins, and reduced A/G ratios.Aged sick hamsters without demonstrable thrombi also had reduced coagulation and fibrinolytic activities and platelet counts, but their fibrinogen levels were markedly elevated, and fibrinogen-fibrin split products were either absent or present in trace amounts. This suggests an earlier and/or less acute form of the thrombotic process.

SummaryA large colony of fawn-hooded (FH) rats, comprising five original families and six generations of their progeny, was developed for genetic and comparative studies of their bleeding tendency. The characteristics of the bleeding diathesis in these rats are similar to those originally reported in related rats by Tschopp and Zucker. FH rats have normal clot retraction, ADP-induced platelet aggregation and platelet ADP ; variable aggregation with collagen; minimal aggregation with adrenaline and cobra venom factor; and reduced platelet ATP, ATP/ADP ratio, serotonin content and 14C-serotonin release. In comparison to age- and sex-matched Wistar rats, FH rats have significantly prolonged partial thromboplastin time, shortened Russell’s viper venom time and increased factor X and XI levels. Other coagulation screening tests and specific assays for fibrinogen, plasminogen and factors VII, VIII and IX were normal. Some age- and sex-related differences in coagulation and other parameters were observed within each rat strain. Plasma proteins, glycoproteins and cerulo-plasmin (copper oxidase activity) showed no abnormalities, nor did initial studies of immunoglobulins and complement. However, FH rats have significantly lower glucose and higher cholesterol levels than comparable Wistar rats.

SummaryA modified 2-stage assay for factor IX which utilizes factor IX deficient plasma plasma from a colony of dogs with Christmas factor deficiency, has been described. The assay is technically less difficult and less time consuming than the established 2-stage assay for factor IX. The assay is more sensitive than other methods currently in use and uses only 4 μl of deficient plasma for a test. Results are comparable to those reported for 1-stage assays, both in vitro and in vivo, with an apparent increase in activity during the conversion of plasma to serum, and with apparently low in vivo recovery of factor IX when infused into a deficient patient.

Complement activation by injured endothelial cells was investigated using ex vivo rabbit thoracic aortas as a source of endothelium and a neutrophil aggregation (NA) bioassay to detect the complement cleavage product C5a (desArg). Endothelium, oxygen-starved by incubating aortas 30 min with Tyrode's buffer, activated complement as demonstrated by a 57% increase in the NA response induced by serum from buffer-treated aortas as compared to serum from untreated control aortas. Incubation of MgEGTA serum in injured aortas resulted in a 27% (P less than 0.025) weaker NA response than normal serum, indicating participation by both classical and alternative pathways of complement activation. Serum from aortas incubated 30 min with 100 micrograms/ml cholestane-3 beta, 5 alpha, 6 beta-triol, a cytotoxic cholesterol oxidation derivative, induced a NA response comparable to that from serum from aortas treated 30 min with Tyrode's buffer. Heat inactivation of serum prior to aortic incubation abolished NA activity and serum incubated in deendothelialized aortas lacked NA activity. Fractionation of serum samples from these experiments on Sephadex G-100 revealed a single peak of NA activity corresponding to the molecular weight of C5a (desArg). Endothelial cell injury was demonstrated by the inability to exclude Trypan blue dye and by scanning electron microscopy. These data demonstrate that damaged arterial endothelium can effectively activate the complement system, resulting in the production of an anaphylatoxic inflammatory mediator.

SummaryTwo of three insolubilized anti-canine FVIII systems removed similar amounts of VIII-C and VIII-RA from canine plasma. These data suggest that VIII-C and VIII-RA form part of one circulating complex.The authors thank Dr. W. P. Webster, Chapel Hill, N.C., for providing the canine hemophilia A plasma and Joanne E. Kull for her assistance in collecting canine plasma samples and immunizing the rabbits.

SummaryA specific complement-reactive factor derived from cobra venom (CVF) inhibited complement activity, impaired clot retraction, and induced aggregation and release of intracellular constituents in plateletrich plasma or suspensions of washed platelets from guinea pigs, rabbits, dogs, and humans. Platelets from thrombopathic dogs and from a complement deficient (C3) patient responded similarly when mixed with purified CVF; possible explanations for these observations are included.We are indebted to Mr. Jack Newman, New York University Medical Center, for testing our CVF preparations for the presence of contaminating fibrinolytic enzymes.