Endocrine, metabolic, internal, and neoplastic causes of pruritus in the dog and cat

Many of the etiologies of pruritus presented herein have been discussed with a view to promoting an awareness of less common causes of pruritus in the dog and cat. For those differential diagnoses that have as yet not been described in our companion animals, the purpose is to stimulate us to look. Of particular interest are the diseases that may cause pruritus without obvious cutaneous pathology. In these instances, the challenge is to make the association. To this end, Table 1 lists those differential diagnoses that would be considered in human beings who have generalized pruritus unassociated with significant cutaneous pathology. Those diseases described to date in the dog and cat have been identified.     

Bluetongue: history, global epidemiology, and pathogenesis

Bluetongue is an arthropod-transmitted viral disease of ruminants and certain other animals that was recognized and described more than 100 years ago in southern Africa. Bluetongue virus (BTV) infection of ruminants and vector Culicoides insects is enzootic throughout tropical and temperate regions of the world; however, there have been drastic recent regional alterations in the global distribution of BTV infection, particularly in Europe since 1998. Multiple novel BTV serotypes also have been detected since 1998 in the south-eastern United States, apparently encroaching from the adjacent Caribbean ecosystem, and novel serotypes of BTV have been identified recently in other historically enzootic regions of the world, including the Middle East and Australia. It has been proposed, but certainly not proven, that global climate change is responsible for these events. BTV infection of ruminants is often subclinical, but outbreaks of severe disease occur with regular frequency especially at the upper and lower limits of the virus' global range where infection is highly seasonal - occurring in the late summer and autumn. Bluetongue disease results from vascular injury, likely through a process analogous to that of human hemorrhagic viral fevers in which production of vasoactive mediators from virus-infected macrophages and dendritic cells results in enhanced endothelial paracellular permeability with subsequent vascular leakage and hypovolemic shock.     

Toxicology of selected pesticides, drugs, and chemicals. Anticoagulant, cholecalciferol, and bromethalin-based rodenticides

The control of rodent pests is a continuing goal of mankind. To this end, a multitude of rodenticides have been produced, each designed to kill rodents by exerting their toxic effects on various body systems. As examples, veterinarians have had to manage companion animal poisonings due to anticoagulant, sodium fluoroacetate (compound 1080), thallium, barium carbonate, and zinc phosphide-based rodenticides. Many of these rodenticides were introduced because of their anticipated safety in relation to nontarget species; unfortunately, this has not been the case. Veterinarians must attempt to identify the specific rodenticide involved in poisoning cases. Therapeutic success in these poisonings is often more dependent upon symptomatic and supportive care rather than the use of antidotal therapy.     

Oral biology and disorders of chiroptera, insectivores, monotremes, and marsupials.

Oral disease occurs in all species, from the tiny marsupial mouse to the large red kangaroo, and from the smallest mole to the largest bat. Although there has been little research done in most of the species in this article, the whole range of dental and oral diseases has been recorded, including periodontal disease, caries, and many variations in position and number of teeth. Hopefully, the interest in these species will continue and further study will enable us to understand these diseases more thoroughly.     

Lymphedema: Clinical Signs, Diagnosis, and Treatment

Medical management of lymphedema is warranted in all dogs with suspected congenital lymphedema, before surgical intervention. Although pharmaceutical agents, such as the benzo-pyrones, have not been investigated for clinical use in dogs, such studies appear to be justified. None of the surgical techniques discussed will cure lymphedema. The only technique reported with any frequency in the dog has been excision of affected tissues, and although some successes have been reported with this procedure, others have found it to be of no benefit or severe complications have occurred. Excisional techniques require meticulous attention to prevent infection intraoperatively and postoperatively. Staging the procedure may decrease problems associated with devascularization of remaining tissues. Evaluation of other techniques may be warranted in dogs; however, no technique has proven to be consistently beneficial in human beings with lymphedema.     

Swine vesicular disease, studies on pathogenesis, diagnosis, and epizootiology: a review

Swine vesicular disease (SVD) is a contagious viral disease of swine. It causes vesicular lesions indistinguishable from those observed of foot-and-mouth disease. Infection with SVD virus (SVDV) can lead to viraemia within 1 day and can produce clinical signs 2 days after a pig has come into contact with infected pigs or a virus-contaminated environment. Virus can be detected 3.5 hours after infection using immunohistochemistry. In these in vitro studies, this technique was superior to in-situ hybridization. In SVDV-infected tissues, however, more infected cells were positive using in-situ hybridization, and these were already seen 4.5 hours after infection. For serological diagnosis of SVD several new enzyme-linked immunosorbent assays (ELISA's) have been developed. The newest ELISAs, based on monoclonal antibodies, are superior to the previous tests. The new tests produce fewer less false-negative results and enable large-scale serological screening. In screening programmes a small percentage of false positive reactors have been detected. The cause of these false-positive reactions has not been identified, though infections with human Coxsackie B5 virus can be excluded.     

Molds, mycotoxins, and mycotoxicosis

Interest in mycotoxins and mycotoxicosis in humans and animals has greatly increased in recent years. Horses have long been considered very susceptible to molds. The signs, treatment, and prevention of several conditions, such as leukoencephalomalacia, aflatoxicosis, ergotism, fescue toxicity, slobbering disease, ryegrass staggers, and moldy sweet clover disease, are discussed.     

Sonography of the liver, gallbladder, and spleen

Focal hepatic and splenic lesions, vascular abnormalities, and disorders of the biliary system can readily be detected with ultrasonography. The sonographic diagnosis can be substantially narrowed when the presenting clinical signs are considered. Ultrasonography is less helpful when the liver or spleen is diffusely involved without parenchymal, abnormalities. However, certain diseases may also be eliminated from diagnostic consideration on the basis of this finding. Percutaneous ultrasound guided biopsy markedly improves the success and safety of obtaining a definitive diagnosis when either diffuse or focal lesions are present. Sonography has also been very beneficial for serially evaluating the response to therapy once focal lesions of the liver or spleen have been identified.     

Pythiosis, lagenidiosis, and zygomycosis in small animals.

Pythiosis, lagenidiosis, and zygomycosis affect animals living in temperate, tropical, and subtropical climates, and these diseases are often fatal. Although Pythium insidiosum, Conidiobolus species, and Basidiobolus species have been recognized as pathogens for several years, members of the genus Lagenidium have been identified as a cause of oomycosis in dogs only recently. Pythiosis, lagenidiosis, and zygomycosis share similar clinical and histologic characteristics, making them difficult to distinguish from one another; however, distinguishing between these pathogens is important because of differences in epidemiology, choice and duration of therapy, and prognosis.     

Sonography of the liver, gallbladder, and spleen

Focal hepatic and splenic lesions, vascular abnormalities, and disorders of the biliary system can readily be detected with ultrasonography. The sonographic appearance in certain cases may be nonspecific, but the differential diagnosis can be substantially narrowed when the presenting clinical signs are considered. Ultrasonography is less helpful when the liver or spleen is diffusely involved without parenchymal abnormalities. However, certain diseases may also be eliminated from diagnostic consideration on the basis of this finding. Percutaneous ultrasound guided biopsy markedly improves the success and safety of obtaining a definitive diagnosis when either diffuse or focal lesions are present. Sonography has also been very beneficial for serially evaluating the response to therapy once focal lesions of the liver or spleen have been identified.     

Stallion Sperm Selection: Past,Present, and Future Trends

Although several selection techniques are available for processing spermatozoa, only colloid centrifugation has been used to any extent in this field, starting with density gradient centrifugation and progressing more recently to single-layer centrifugation (SLC). SLC through a species-specific colloid has been shown to be effective in selecting spermatozoa with good motility and normal morphology from stallion semen. The method is easier to use and less time-consuming than density gradient centrifugation, and has been scaled-up to allow whole ejaculates to be processed in a practical manner. The potential applications of SLC in equine breeding are as follows: to improve sperm quality in artificial insemination doses for “problem” ejaculates, to increase the shelf life of normal sperm doses, to remove pathogens (viruses, bacteria), to improve cryosurvival by removing dead and dying spermatozoa before freezing or after thawing, to select spermatozoa for intracytoplasmic sperm injection, and to aid conservation breeding.     

Comparative approach to health maintenance: definition, need, and rationale.

A comparative approach has been employed in many phases of medicine, eg, epidemiology, surgery, nutrition, cancer. It has been used widely in teaching, research, and surveillance, but little attention has been paid to its application in delivery systems. Geographic and financial circumstances often create situations in which it is extremely difficult to enter the health care system or even to know when such entry is indicated. Because the comparative approach has been successful in other phases of medicine, it deserves consideration in the health maintenance phase. The comparative approach has three major components: (1) Reliance on broad principles of health maintenance, not on specifics; (2) emphasis on health maintenance, not on curative medicine; and (3) utilization of health care systems designed for nonhuman beings to bring man into the human health care system. The ways to utilize ethically and legally the expertise of other health professionals in providing entry to the health care system and in facilitating transfer of our technical knowledge to more of the general public should be explored.     

Pruritus in rabbits, rodents, and ferrets

This article attempts to cover the more specific pruritic problems encountered in rabbits, rodents, and ferrets. There are certainly other causes of pruritus in these animals. Dermatophytes in guinea pigs are not reported to be pruritic, but because they are pruritic in other species, they should be considered in a differential diagnosis. A cryptococcal dermatitis in a guinea pig that was pruritic has been reported. Although mites were not seen on scraping, the animal was treated for sarcoptid mites and apparently the pruritus lessened. Because the cryptococcis was still present, it is questionable whether it was causing the pruritus. Pruritic ulcerative dermatitis over the back and shoulders has been seen in some lines of rats. Staphylococcus aureus was cultured from many of the lesions. Clipping the toenails on the feet helped lessen the severity of the lesions. Syphacia spp. have been reported in rats, gerbils, and hamsters and should be considered if there is perineal pruritus. MOBS, or "move over buddy syndrome," is seen especially in mice and may be seen in hamsters, gerbils, and rats that are overcrowded or stressed. The lesions are actually bite wounds that have been inflicted around the tail base and the perineum and on the tail, but these wounds can be mistaken for self-inflicted trauma from pruritus. All of the recommended treatments are extralabel, and clients should be informed of this. I have observed a guinea pig become lethargic and anorexic after only one application of a flea powder approved for use in cats. Brushing most of the powder off and offering dandelion greens to stimulate appetite helped. The second dusting was done with the same flea powder diluted with baby powder. Whenever these animals are dipped, it is important to let them dry in a warm, draft-free area. Again, it is important to be aware that the ratio of surface area to body weight is much higher in these small animals than in the species routinely seen in veterinary practice especially to prevent toxicoses from topically applied medications and iatrogenic hypothermia or hyperthermia.     

Toxicology of selected pesticides, drugs, and chemicals. Zinc

Zinc poisoning in small animals has been described in dogs, cats, birds, and ferrets, but the dog appears to be the species most often affected. Ingestion of zinc-containing metallic objects, including pennies, and zinc oxide ointments has been associated with the majority of the toxicoses. Clinical signs include anorexia, vomiting, diarrhea, hemolytic anemia, kidney dysfunction, and possible liver and pancreatic abnormalities. Treatments that have proven efficacious include fluid diuresis, blood transfusions as needed, general supportive care, and removal of the source of zinc. Further evaluation of the benefit of chelation therapy is urgently needed.     

干法消化——ICP-AES法测定饲料中钼、硫、钨

应用ICP-AES对饲料中的钼、硫、钨的测定进行了研究,确定了合理的测试条件,回收率达88%～104%,结果令人满意。该法可同时检测饲料中的多种元素,且精密度高,进样量少,节省试剂,方便快捷。     

Measurement, interpretation, and implications of proteinuria and albuminuria.

Proteinuria is a common disorder in dogs and cats that can indicate the presence of chronic kidney disease (CKD) before the onset of azotemia or the presence of more severe CKD after the onset of azotemia. Although a direct pathogenetic link between glomerular disease, proteinuria, and progressive renal damage has not been established, attenuation of proteinuria has been associated with decreased renal functional decline in several studies. There is a need to continue to increase our understanding of the effects of proteinuria on the glomerulus, the tubule, and the interstitium in dogs and cats.     

Equine stereotypic behaviors: Causation,occurrence, and prevention

There are strong suggestions that equine stereotypies are connected to poor welfare and a suboptimal management and/or stabling environment. Different forms of equine stereotypic behaviors have been described. Crib biting, weaving, and box walking are considered the most prevalent. Several studies have been conducted to establish links between the underlying causes and potential function of such behaviors. Both experimental and epidemiological studies have indicated management factors specifically feeding practices, housing conditions, and weaning method as crucial in the development of stereotypies in stabled horses. Some neurological studies on equine stereotypy demonstrated some forms of central nervous system dysfunction as being associated with the performance of stereotypic behaviors. Different researchers hypothesized that the functional significance of stereotypies is that they reduce stress in captive environments and should thus be considered as a coping mechanism. In contrast, the owner's perspective is often that a stereotypic horse has a “stable vice” that needs to be stopped, and different kinds of methods have been developed to control or regulate stereotypic behaviors. However, if the stress-reducing hypothesis is correct, controlling stereotypic behaviors particularly by physical and surgical approaches without addressing the underlying causes is of great concern to the horse's welfare. Although there is ongoing uncertainty about the exact function, the growing knowledge about causation should be applied: under all circumstances prevention is better than cure.     

Calcium, phosphorus, and magnesium homeostasis in ruminants

Significant advances have been made in the last 30 years in the understanding of Ca, PO4, and Mg homeostasis in ruminants. Despite these advances, the primary cellular or molecular lesions responsible for failure of homeostasis have yet to be identified. Suggested causes, such as primary hormone deficiencies, have been eliminated, and we now believe that aging and nutrition can reduce the ability of intestine, bone, and kidney to respond rapidly to the hormone signals responsible for homeostasis during rapid increases in demand for these minerals. Further research is required before these lesions can be identified and new knowledge applied to the development of economical, effective programs that prevent milk fever and hypomagnesemic tetany. Until then, diseases such as milk fever will continue to affect 8 to 9 per cent of our dairy cows, and dairy farmers will continue to spend millions of dollars a year for treatment of the primary disease and the many secondary problems that result from these diseases.