Control of selection bias in parallel-group controlled clinical trials in dogs and cats: 97 trials (2000-2005)

OBJECTIVE: To determine how selection bias (allocation bias) was controlled in published clinical trials. DESIGN: Retrospective study. SAMPLE POPULATION: 97 parallel-group controlled clinical trials published from January 2000 through December 2005 in 12 peer-reviewed journals. PROCEDURES: Journals were hand searched to identify eligible reports. Details concerning allocation of animals to study groups, baseline characteristics of the groups, and the number of animals allocated to each group were recorded. RESULTS: Randomization was the stated method of allocating animals to groups in 87% of the reports, yet in only 11% of reports were both randomization of the group allocation process and concealment of the allocation sequence described. Studies reported as randomized were more likely to report baseline characteristics of the study groups for comparison than studies that did not report randomization (88% vs 54%). Studies in which baseline group characteristics were reported had more subjects allocated to each study group (median, 16) than those that did not (median, 11). CONCLUSIONS AND CLINICAL RELEVANCE: Randomization was reported as the method of allocating study animals to groups in most publications, indicating that the potential power of randomization in controlling selection bias is appreciated by clinical investigators seeking to determine the efficacy of an intervention. However, in most reports, little corroborating information was included to support the claim. The absence of this information makes it difficult for practitioners to critically review the impact of bias on study results and make informed decisions regarding patients.     

Sources and handling of losses to follow-up in parallel-group randomized clinical trials in dogs and cats: 63 trials (2000-2005)

OBJECTIVE: To determine the sources and handlingof losses to follow-up (LTF) in parallel-group randomized clinical trials (RCTs). SAMPLE POPULATION: 63 parallel-group RCTs of > 24 hours' duration published from January 2000 through December 2005. PROCEDURES: Journals were hand searched for eligible reports. Details concerning the presence, cause, and amount of LTF; statistical handlingof data missingbecause of LTF; type of analyses performed; number of animals randomly allocated and analyzed; and the acknowledgement of the potential impact of LTF were recorded. RESULTS In 81% (51/63) of trials, LTF were reported. In 80% (41/51) of those studies, losses in the analysis were ignored, and in only 18% (9/51) was the potential impact of LTF on study results acknowledged. Of the 47 studies in which sources of LTF were reported, 72% had loss of subjects because of investigator withdrawals, 30% because of deaths, and 26% because of owner withdrawals. Median loss of subjects for those studies was 12% because of investigator withdrawal (range, 2% to 52%), 8% because of death (1% to 28%), and 4% because of owner withdrawal (2% to 33%). CONCLUSIONS AND CLINICAL RELEVANCE: Most RCTs had LTF, most of which were attributable to investigators removing randomly allocated animals from the study. In most studies, data from animal LTF were ignored and, therefore, only a subgroup of randomly allocated subjects was included in the data analysis. Most reports did not address the potential for a postrandomization selection bias associated with ignoring LTF and did not acknowledge the potential impact of the missingdata on their results.     

Postoperative pain control in cats: clinical trials with medetomidine and butorphanol

OBJECTIVE: To evaluate the analgesic effects of medetomidine (MED) and butorphanol (BTO) in cats after ovariohysterectomy. STUDY DESIGN: A placebo-controlled, blinded monocenter clinical study. ANIMALS: Healthy adult female client-owned cats. METHODS: Sixty-four cats weighing 3.15 +/- 0.6 kg, presented to the University of Helsinki's Small Animal Teaching Hospital for routine elective ovariohysterectomy, received MED at 15 microg/kg (n = 18), BTO at 0.1 mg/kg (n = 23), or saline (PL) (n = 23) intramuscularly immediately after ovariohysterectomy. Level of pain perception, degree of restlessness, and extent of sedation were scored subjectively before and at 30, 60, 90, and 120 minutes after test-drug administration. RESULTS: BTO provided the best pain relief, followed by MED. Saline provided the least pain relief. Both MED and BTO effectively and identically prevented postoperative restlessness. MED and BTO produced an identical degree of sedation that was better than the PL. CONCLUSIONS: Both MED (at 15 microg/kg) and BTO (at 0.1 mg/kg) prevent postoperative pain in cats after ovariohysterectomy. Clinical Relevance-MED and BTO are useful for preventing postoperative pain in cats.     

Porencephaly in dogs and cats: magnetic resonance imaging findings and clinical signs

Magnetic resonance imaging (MRI) features of brain lesions in 5 dogs and 2 cats characterized by extensive cystic changes of the cerebral hemispheres in terms of a porencephaly are presented. Age at diagnosis ranged from 12 weeks to 7 years. MRI findings were confined to the forebrain. Porencephalic lesions appeared as wedge-shaped parenchymal defects connecting the ventricular system and the subarachnoid space or as large cystic defects in the cerebral hemispheres. Although in two adult dogs the porencephalic lesions were asymptomatic, the other animals showed clinical symptoms depending on the affected cerebral area. Three animals had seizures. Interestingly, four animals showed neurological signs normally not localized to the forebrain (nystagmus, hypermetria, ataxia). Whether these clinical signs are related to impaired function of the cerebral cortex or to not recognizable lesions in the cerebello-vestibular system could not be further clarified. Although the defects develop intrauterine or postnatal, the clinical symptoms can occur later in life. The definition of porencephaly as well as its subclassification is not uniform in veterinary medicine. We suggest the term encephaloclastic porencephaly unregarding the underlying cause of the defect, which cannot be further specified by diagnostic imaging.     

Histoplasmosis in dogs and cats

Histoplasma capsulatum is endemic throughout most of the United States with a high prevalence of infections in the Midwest and South. Histoplasmosis is the second most common systemic fungal disease in cats that may be more susceptible than dogs. Infection occurs by inhalation of conidia from the mycelial phase, which subsequently convert to the yeast form. Histoplasma capsulatum is phagocytized and harbored by cells of the mononuclear phagocyte system. Infection may be subclinical or cause clinical pulmonary granulomatous disease or dissemination. Disseminated disease predominantly affects the liver, spleen, gastrointestinal tract, bone and bone marrow, integument, and eyes. Primary gastrointestinal histoplasmosis also occurs. Clinical signs of histoplasmosis often are nonspecific, including chronic wasting, fever, anorexia, respiratory signs, and lameness. Gastrointestinal signs (eg, diarrhea with hematochezia or melena) are common in dogs. The definitive diagnosis is made by identification of the yeast in tissue samples. Itraconazole is the treatment of choice.     

Coccidioidomycosis in dogs and cats: a review

The dimorphic fungi Coccidioides immitis and Coccidioides posadasii are the causative agents of coccidioidomycosis. Dogs and cats residing in and visiting endemic areas are at risk of exposure to infectious arthrospores. The primary infection is pulmonary and frequently results in chronic cough. Disseminated disease is common and causes cutaneous, osseous, cardiac, ocular, nervous system, or other organ disease. Radiographic changes include a variable degree of interstitial pulmonary infiltration, hilar lymphadenopathy, and osseous lesions. Serological titers support the diagnosis, but definitive diagnosis relies on identification of Coccidioides in cytological or tissue samples. Coccidioidomycosis should be considered in any dog or cat that has been potentially exposed during the previous 3 years and is presented with chronic illness, respiratory signs, lameness, lymphadenopathy, nonhealing cutaneous lesions, or neurological, ocular, or cardiac abnormalities.     

Proteinuria in dogs and cats

Proteinuria is defined as the presence of protein in the urine. Normally, circulating serum proteins are blocked by the glomerulus due to size and/or charge. Any small proteins that pass through a healthy glomerulus are reabsorbed by the renal tubules or broken down by renal tubular epithelial cells. Persistent proteinuria, in the absence of lower urinary tract disease or reproductive tract disease, is usually an indication of renal damage or dysfunction. Less commonly persistent proteinuria can be caused by increased circulating levels of low molecular weight proteins. This article reviews mechanisms of proteinuria in dogs and cats and discusses the importance of screening for and ultimately treating proteinuria.     

Ringworm in dogs and cats

Ringworm is an uncommon disease of dogs, but cats, especially the longhaired breeds, are more frequently infected. Of the several dermatophytes involved, Microsporum canis causes 94 per cent of ringworm in cats and 65 per cent in dogs. This species is highly contagious for man but the true incidence of human infection is unknown. Ringworm caused by M canis usually responds readily to treatment, but when the infection establishes in a colony of cats, eradication can be difficult and expensive. Other forms of ringworm in dogs and cats are caused by dermatophytes acquired from wild animals, mainly small rodents such as mice and voles. This is an uncommon and trivial disease of cats, but some infections in dogs can be remarkably persistent and difficult to resolve.     

Sporozoa in dogs and cats

SUMMARY Faecal samples from 110 dogs and 71 cats were examined for sporozoan parasites by flotation. Isospora spp were present in 5.5% dogs and 4.2% cats; Sarcocystis spp in 20.9% dogs and 1.4% cats. 74.5% dogs and 77.5% cats were fed raw meat from various sources; beef was fed most often. Animals fed raw meat were more frequently infected with protozoa. No Toxoplasma oocysts were found. The results are compared with those from other surveys in Australia and New Zealand.     

Campylobacteriosis in dogs and cats: a review

Campylobacter species are commonly isolated from faecal samples collected from dogs and cats, with the most prevalent species being C. upsaliensis, C. helveticus, and C. jejuni. Although the majority of dogs and cats are subclinically infected, some will develop mild to moderate enteritis. Immature animals, animals from intensive housing backgrounds, and animals with concurrent disease are especially predisposed to infection and the development of clinical signs. Bacterial culture methods applied in diagnostic laboratories remain biased to C. jejuni and C. coli detection, but molecular methods to diagnose Campylobacter spp. infections in dogs and cats have become widely available and can aid rapid and accurate diagnosis. Multilocus sequence typing has also been developed for subtyping different strains and has been used in epidemiological investigations. In the majority of cases, clinical signs are self-limiting and antimicrobial treatment is not warranted. Campylobacter spp. isolated from dogs and cats have shown resistance to commonly used antimicrobials, so antimicrobial therapy should only be administered where this is justified. Contact with dogs and cats is a recognised risk factor for human campylobacteriosis, thus people living or working in close contact with cats and dogs should be made aware of the zoonotic organisms these animals can shed.