Submitted by: Patricia Shea, DVM
J Sm Anim Pract 2020. DOI: 10.1111/jsap.13214
The use of hydrolysed diets for vomiting and/or diarrhoea in cats in primary veterinary practice
Kathrani A, Church DB, et al.
Cats presenting with chronic vomiting and/or diarrhea, implying the presence of these clinical signs for at least 2 weeks, are seen every day in primary veterinary practice. Although some of these cases have non-gastrointestinal diseases as their etiology, a significant number are associated with feline chronic enteropathy (CE), which comprises an assemblage of diseases resulting in ongoing clinical signs referable to gastrointestinal disease. The etiopathogenesis of feline CE is likely multifactorial, with genetic susceptibility, environmental risk factors, intestinal dysbiosis, and altered gastrointestinal mucosal immune response all speculated to play a role, either separately or in combination.
While definitive diagnosis of feline CE requires a rigorous workup involving a laboratory minimum database, specialized laboratory panels, fecal testing, abdominal ultrasonography, and gastrointestinal histopathology obtained through endoscopy or exploratory surgery, it is likely that many cats evaluated for chronic vomiting and diarrhea in primary veterinary practice do not undergo such an extensive workup due to owner financial constraints, contraindications to general anesthesia, and other logistical concerns. Treatment of feline CE can involve the use of endoparasiticides, antibiotics, therapeutic diets, and anti-inflammatory or immunosuppressive medications. These therapies are probably often given to cats empirically in general practice without the full gamut of recommended diagnostic testing.
One treatment often recommended and sometimes successful in the treatment of feline CE, either as a single agent or in combination with other therapeutic modalities, is diet. Commercial hydrolyzed, limited ingredient novel protein, highly digestible, and high fiber diets have all been used for suspected or confirmed feline CE. The current study investigated the use of hydrolyzed diets used in suspected or confirmed cases of feline CE in primary practice, either alone or in combination with other therapies.
The first aim of the study, which used the anonymized electronic medical records of cats with chronic vomiting and/or diarrhea of unknown etiology, was to determine the outcome for these patients prescribed a hydrolyzed diet with or without concurrent or prior antibiotic and/or glucocorticoid treatment. Secondly, the researchers wanted to know if antibiotic or glucocorticoid therapy for chronic vomiting and/or diarrhea prescribed before or at the same time as the hydrolyzed diet was associated with response.
Electronic medical records of 512,213 cats who were patients in 2016 of 876 primary care practices participating in a nationwide database program in the United Kingdom were accessed. Out of this search, the records of 5,569 cats prescribed a hydrolyzed diet for chronic vomiting and/or diarrhea were identified. The records of 90% (5,000) of these animals were randomly selected for further evaluation. Criteria for inclusion of a record in the study were as follows:
- hydrolyzed diet prescribed for persistent or intermittent vomiting and/or diarrhea of at least 2 weeks’ duration;
- no evidence of concurrent diseases (such as dermatological conditions) for which a hydrolyzed diet could also have been prescribed;
- no history of the diet being refunded or discontinued within one month of dispensing;
- referral notes available if the cat was referred for gastrointestinal clinical signs;
- at least 6 months of follow-up records at the same general practice unless the cat died or was euthanized due to gastrointestinal signs;
- diagnostic investigations demonstrated no other etiology for the chronic vomiting and/or diarrhea other than chronic inflammatory enteropathy.
Out of the 5,000 feline medical records evaluated, 1,565 were determined to have chronic vomiting and/or diarrhea referable to feline CE, and of these, 977 met all of the inclusion criteria. A flow chart is provided in the article showing how the exclusion criteria selected the 977 patients ultimately included in the study. Of the 977 cats included in the study, 107 had inflammatory changes in their intestines documented by histopathology.
A response was considered poor if the patient needed intervention with antibiotic or glucocorticoid therapy for the vomiting/diarrhea at a visit subsequent to the one in which the hydrolyzed diet alone was prescribed, or if death or euthanasia associated with the gastrointestinal clinical signs took place within the minimum 6-month follow-up period. This category comprised 240/697 (34%) cats; the median follow-up time for this group was 818 days (range 184-3,809 days). This means that 66% of the cats in this group had a good response to the hydrolyzed diet alone.
Poor response in patients receiving the prescription diet and glucocorticoids (with or without antibiotic therapy) concurrently was defined as subsequently receiving additional glucocorticoid or antibiotic therapy for vomiting/diarrhea at least 3 months after the diet was prescribed, or death from gastrointestinal signs in that period. This category included 100/153 (65%) patients considered to have a poor response; median follow-up time in this group was 946 days (range 186-3,599 days).
Of the 127 cats receiving antibiotic therapy only (no glucocorticoid) at the time the hydrolyzed diet was first prescribed, 71 (56%) were also considered to have a poor response, because either they needed intervention with additional antibiotic and/or glucocorticoid for vomiting/diarrhea at a visit subsequent to the one at which the hydrolyzed diet was prescribed, or they died or were euthanized due to gastrointestinal signs within the follow-up time.. Median follow-up time in this third group was 1082 days (range 213-3,888 days).
The final multivariable model created from this study demonstrated that cats over 6 years of age prescribed the hydrolyzed diet had greater odds of a poor response than cats 6 years of age or less. A better response to dietary therapy for chronic enteropathy has also been demonstrated in younger dogs. Cats that were prescribed antibiotic and/or glucocorticoid before being prescribed the hydrolyzed diet, and those receiving antibiotic or glucocorticoid at the time the diet was prescribed, had increased odds of a poor response compared to those who did not receive these drugs either before starting the diet or concurrently with beginning the diet. It is likely that at least some of the patients exhibiting a poor response had more severe clinical signs or more deranged results on diagnostic evaluations than those prescribed the diet only. Variables that were not associated with increasing the odds of a poor response included sex, spay/neuter status, coat color, and breed.
Although there were a number of limitations to this study, such as inclusion of only those cats with vomiting, diarrhea or both, and exclusion of cats with other clinical signs possibly referrable to CE, such as weight loss, hyporexia or polyphagia, a therapeutic trial of a hydrolyzed diet before starting medications could be worthwhile in a feline patient presenting with chronic vomiting and/or diarrhea not attributable to extra-gastrointestinal disease. In the present study, 42% of the cats prescribed a hydrolyzed diet with or without concurrent medications had a poor response in the study follow-up period of 6 months or more. However, that means that 58% had a good response to hydrolyzed diet therapy in the follow-up period, especially younger cats.
J Am Vet Med Assoc 2020. DOI: 10.2460/javma.257.9.929
Effect of ultraviolet germicidal irradiation of the air on the incidence of upper respiratory tract infections in kittens in a nursery
Jaynes RA, Thompson MC, Kennedy MA.
Control of viral and bacterial pathogens in shelters and other group housing facilities for animals is critical to the well-being and survival of the animals these facilities serve. Respiratory pathogens are among those responsible for significant morbidity rates in group-housed cats. Feline herpesvirus-1 (FHV-1), feline calicivirus, Chlamydophila felis, Mycoplasma spp., and Bordetella bronchiseptica are the five most common pathogens involved in feline upper respiratory infections. At least three of these (FHV-1, feline calicivirus, and Bordetella bronchiseptica) are certainly or probably spread through aerosol transmission, either via direct inhalation of infected aerosolized droplets by susceptible animals, or contact with surfaces upon which aerosolized respiratory droplets have deposited.
Although many shelters have made significant strides in reducing the risk of upper respiratory infections (URIs) in their feline populations by improving husbandry and decreasing stress, ideally the removal of respiratory pathogens from the air in the first place would reduce the risk of transmission via inhalation or through contact with contaminated surfaces. FHV-1 and feline calicivirus are known to survive on surfaces for 2 days and 7 days, respectively.
In this study of 4- to 8-week-old kittens admitted to a kitten nursery in 2016 and 2018, the effects of two ultraviolet germicidal irradiation systems on the incidence of URIs in this feline population were studied. Ultraviolet germicidal irradiation (UVGI) systems are known to disinfect water, environmental surfaces, and the air, and have been successful in reducing the incidence of respiratory tract infections in humans. However, no studies of the efficacy of these systems in reducing infectious disease in animal shelters have previously been reported. Two UVGI systems were installed in the kitten nursery, one within the heating, ventilation, and air conditioning (HVAC) system, and the other, attached to the ceiling with a blower that irradiated the air surrounding (360°) the unit. The UVGI systems were installed in the kitten nursery of a humane society in 2017, prior to the April-November 2018 kitten season, during which time the facility was used to house 4- to 8-week-old kittens and sometimes nursing queens. No UVGI systems were present in the kitten nursery when it was open from May to November of 2016 and housed a similar cohort of kittens and nursing queens.
Kittens surrendered to the shelter by the public, as well as those from a kitten bottle-feeding program on a separate shelter campus, received physical examinations upon arrival at the nursery and were only admitted if they showed no clinical signs consistent with respiratory illness. The kitten nursery was a free-standing building on the humane society campus, and only those workers and volunteers who worked directly with the kittens were admitted to the nursery building. The nursery building was always empty and completely disinfected prior to admitting a new cohort of animals at the beginning of kitten season. The nursery HVAC system provided 9 air changes per hour in all areas of the building; 5-8 air changes/hour is the standard recommended for animal care facilities. Nursery personnel also consistently followed standard operating protocols for cleaning and disinfecting the facility on a daily basis, and personal protective equipment was always worn and changed appropriately.
Diagnosis of a URI in a kitten was based only on physical examination findings by shelter veterinarians. Clinical signs considered compatible with a diagnosis of URI included sneezing, conjunctivitis, nasal and ocular discharge, high body temperature, inappetence, and oral ulceration. URI incidence for the two years compared (2016, when no UVGI systems were present in the nursery, and 2018, when both UVGI units were present and operating continuously in the nursery) were calculated as the number of URI cases per 100 kitten admissions to the nursery. In 2016, out of 444 kittens admitted to the nursery, 55 kittens with URIs were diagnosed; therefore, the incidence of URI in this year was 12.4 cases/100 kittens admitted. In 2018, 698 kittens were admitted to the nursery, and only 11 cases of URI were diagnosed in this population; the incidence of URI in this year decreased to 1.6 cases/100 kittens admitted.
Based on the findings of this study, the authors concluded that airborne transmission of respiratory pathogens through HVAC systems is a significant factor in the spread of URIs in animal shelters. Cleaning and disinfection of surfaces as well as stress reduction strategies, while important, are not the only means of controlling transmission of infections among animals in group housing. Although it is possible that some kittens could have been infected with URIs prior to nursery admission, but did not display clinical signs until after admission, or were infected with URIs during their nursery stay without showing clinical signs until after discharge, the results of the study suggest that UVGI systems are helpful in reducing the transmission of URIs in shelters. Because the causative agents in the URIs were not definitively diagnosed in the present study, no conclusions can be drawn regarding the effectiveness of UVGI systems in reducing the incidence of URIs caused by specific pathogens. Additional studies would be required to determine if only one type of UVGI system (HVAC or ceiling mount) is effective in reducing URI incidence on its own.
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