Submitted by: Patricia Shea, DVM
Am J Vet Res 2020; 81:448-452.
Randomized controlled trial to evaluate a novel two-catheter technique for urethral catheterization in anesthetized healthy female cats and small dogs.
Abrams BE, Selmic LE, et al.
Female cats require urethral catheterization rarely, but when they do, the procedure can be technically challenging due to the animal’s small size and inability to visualize the anatomic pathway. Moreover, irritation of or injury to the patient is possible when there are multiple unsuccessful attempts to pass the urinary catheter.
This study evaluated a new technique for passing a urethral catheter in these small patients involving the use of two sterile catheters. The patients included 24 cats as well as 15 small dogs who had been anesthetized for ovariohysterectomy. These animals were healthy; subjects with abnormal body condition, urinary tract infections, or abnormal external genitalia were not included in the study.
The novel urethral catheterization procedure involved the use of a large (10 Fr) catheter in the cats as a guide for the smaller (5 Fr in the cats) urethral catheter. Using sterile technique, the large catheter was first advanced into the anesthetized cat’s vagina. Once the tip of this catheter could no longer be advanced cranially, its open end was reflected dorsally and held in place as the smaller urethral catheter was inserted ventral to the large catheter. The urethral catheter was then advanced along the midline of the vestibule at about a 45-degree angle until this catheter moved through the urethral orifice.
Veterinary professionals selected to participate in the study were termed “catheter placers” (CP). Two CPs were board-certified veterinary surgical specialists, one of whom was experienced in the new technique, and one who was not. A veterinary surgical intern with no experience in the novel technique was the third CP. The study also compared the use of standard urethral catheterization techniques in these small patients with the novel technique. One CP performed catheterization in each animal with the new technique as well as traditional techniques. The order in which the techniques were performed was randomized. If a catheter could not be successfully placed within 3 minutes using a given technique, that attempt was considered a failure.
Urethral catheterization using the novel technique was successful in 19 of the 24 cats, resulting in a success rate of 79%. In contrast, use of standard techniques for this procedure resulted in successful catheterization of only 12/24 cats, or a 50% success rate. Median time for urethral catheter placement was 48 seconds in the entire patient group using the novel technique, and 41 seconds using traditional methods. Clinician experience did not make any difference with respect to the success rate or time required to place the urinary catheters.
Submitted by: Ashlie Saffire, DVM, DABVP (Feline)
Vet Dermatol 2021;32:26-e6.
Clinical signs and diagnosis of feline atopic syndrome: detailed guidelines for a correct diagnosis.
Santoro D, Pucheu-Haston C, et al.
This review article is the third in a series of four focused on the feline atopic syndrome. Previous articles in this series were summarized in the February and April 2021 issues of The Scratching Post. Feline atopic syndrome (FAS) comprises a spectrum of allergic diseases in cats, including allergic dermatitis, allergic airway diseases including asthma and other allergic respiratory diseases, and gastrointestinal diseases whose etiology is associated with hypersensitivity to environmental allergens and foods.
In creating this review, the authors compiled data from 107 publications discussing feline allergic diseases grouped under the FAS umbrella. The results of this study emphasize the strong connection between cutaneous, gastrointestinal, and respiratory allergic syndromes in cats. Extracutaneous clinical signs of allergy, including respiratory signs in 8.3% of cats with FASS and 11.5% with food allergy, ocular signs in 4.8% with FASS and 12% with food allergy, and gastrointestinal signs in 3.9% with FASS and 18.1% with food allergy, are noteworthy. Although this paper represents an exhaustive and extensive review of the published literature regarding feline allergic diseases, the authors point out that relatively little research in this area has been done, and much of how we characterize, diagnose and treat these diseases is extrapolated from dogs and humans.
A cat affected with FAS may also have a coexisting flea allergy dermatitis (FAD). Therefore, very strict flea control is required to rule out FAD. Feline atopic skin syndrome (FASS) is a subset of FAS in which hypersensitivity and dermatitis is associated with environmental allergens; a former term for this syndrome is “nonflea, nonfood-induced feline hypersensitivity dermatitis.” Some cats with FASS will have a coexisting food allergy. Diagnosis of FASS is based on history and clinical signs, as well as exclusion of other diseases with similar clinical signs.
A variety of cutaneous lesions can be associated with FASS. A much broader spectrum of cutaneous reactions occurs in cats with FASS than in atopic humans or dogs. The most common cutaneous reactions in cats with FASS are four: miliary dermatitis (MD), self-inflicted alopecia/hypotrichosis (SIAH), head and neck pruritus (HNP), and eosinophilic granuloma complex (ECG). All of these lesional patterns can also be seen with flea allergy dermatitis (FAD) or feline food allergy (FFA), either or both of which can coexist with FASS. Two or more of these cutaneous reaction patterns may be present in FASS. Atypical lesions of FASS include pododermatitis (with or without plasma cell involvement) and alesional pruritus.
Signs of FASS may appear for the first time in cats any time from six months of age to 15 years; however, the majority of animals with FASS experienced a young age of onset, from 0.5 to 4.8 years. Review of previous publications suggests that there is some female predilection, with approximately 58% of the cats with FASS being female, and 42% male. All of the aforementioned lesional patterns can also be seen with flea allergy dermatitis (FAD) or feline food allergy (FFA). Little information is available regarding the heritability of feline allergic diseases; Abyssinians and Abyssinian crosses are one group that appear predisposed to FASS.
Other diseases on the FAS spectrum, including feline food allergy (FFA) and feline asthma and their diagnosis, are discussed in this review. Because of the complete overlap of cutaneous signs of FFA and FASS, the authors state that it is essential to perform a strict dietary trial to rule in or rule out FFA before beginning diagnostics for FASS. Anti-inflammatory medications may be provided in the initial stages of the dietary trial for maintenance patient comfort and quality of life. In some cases a second dietary trial may be required to rule out FFA with certainty. Other differential diagnoses for FASS, including ectoparasitoses, FAD, and staphylococcal and Malassezia overgrowth/infection, are discussed, along with the importance of ruling out and treating these conditions prior to working up the patient for allergic skin disease. Diagnosing and eliminating these additional sources of pruritus prior to embarking on evaluation of the patient for FASS allows the clinician to get the best impression possible of the true severity of the FASS, and promotes optimal, efficient management of this condition.
Feline asthma is very similar clinically and pathogenetically to human asthma. There is no specific testing available that is routinely diagnostic for feline asthma. To a large degree, feline asthma is a diagnosis of exclusion, in which ruling out other pulmonary, thoracic, and cardiac diseases that present with similar clinical signs, is essential. Diagnostic modalities employed in the diagnosis of feline asthma are briefly discussed in the paper.
Finally, the authors discuss the role of allergen testing in suspected cases of FASS. Allergen testing, which is not diagnostic, but rather supports the diagnosis of FASS, should be the last step in the process, after FASS has been diagnosed by excluding other disorders. These tests identify the allergens which are likely to be triggering the disease and which may be targeted for allergen-specific immunotherapy (ASIT). Allergen testing may be performed with intradermal testing (IDT), which detects the presence of allergen-specific IgE bound to cutaneous mast cells, and/or allergen-specific IgE serology (ASIS), which identifies circulating allergen-specific IgE in a blood sample.
IDT results are more difficult to interpret in cats than in dogs or horses, possibly because the stress associated with veterinary visits causes a rise in serum cortisol and epinephrine in many cats, which in turn may blunt the reactivity of the test. Both false-positive and false-negative results can be obtained with either IDT or ASIS. In a few studies, the concentrations of allergens (grass, weed, and tree pollens) used in canines are too low, which may also explain some of the low IDT reactivity in cats. Percutaneous prick testing (PPT), mostly used in humans, is different from IDT, which requires intradermal injection of allergens. In PPT, the allergen is placed on the skin surface, and then the skin is pricked with a needle or other device, allowing the allergen to be absorbed. A few studies in the last decade using new tools for allergen administration that allow the allergens to be placed in a standardized fashion have piqued interest in the use of PPT in cats.
ASIS is more commonly used by general practitioners than IDT: it is easier to perform and interpret, but only measures circulating IgE in the blood. With ASIS, positive reactions can be obtained in nonallergic healthy cats. The accuracy of either IDT or ASIS is unknown in the cat, and response to treatment (ASIT) with allergens identified as probable causes of pruritus is likely the best measure of the accuracy of these tests in the individual patient.
In atopic dogs, the most common allergen implicated is household dust mites. Although there are, as usual, fewer feline studies, pollens (grass, weed, and/or tree) and insects were the most common allergens identified with IDT, followed by reactions to household dust mites. With ASIS in cats, the patterns of predominant allergens identified and reported in the literature are less straightforward.