CHARACTERIZATION OF PHYSIOLOGIC 18F‐FDG UPTAKE WITH PET‐CT IN DOGS

We evaluated the whole body distribution of 2‐deoxy‐2‐[18F]fluoro‐d ‐glucose (¹⁸F‐FDG) in seven beagle dogs using positron emission tomography/computed tomography. The mean and maximum standard uptake values (SUV) for various tissues were computed. The SUV of the aortic blood pool was 0.65±0.19. Moderate uptake was present in brain (3.40±1.01). Mild uptake was present in orbital muscles, soft palate, laryngeal and pharyngeal region, mandibular salivary gland, myocardium, liver, pancreas, kidney, and intestine. ¹⁸F‐FDG uptake would be normally higher in these tissues because of normal physiologic activity. Mean and maximum SUV values of the eye, skeletal muscle, bone tissue, spleen, adrenal gland, stomach, tongue, gall bladder, and lung were similar to or lower than that of the aortic blood pool. These data provide a normal baseline for comparing pathologic ¹⁸F‐FDG uptake.     

Severe hydrocephalus in a raccoon dog (Nyctereutes procyonoides)

Hydrocephalus is one of the most common central nervous system malformations in domestic dogs, yet they are poorly documented and studied in wild carnivoran mammals. A pup of raccoon dog (Nyctereutes procyonoides) was rescued and brought to Wildlife Center. The pup showed generalized ataxia, a domed skull, and an open bregmatic fontanelle. Ultrasound and MRI showed severe enlargement of the lateral ventricle with the loss of septum pellucidum resulting in a single large ventricle and cervical syringohydromyelia. Although treatment was attempted, the animal was euthanized due to poor prognosis. At necropsy, macroscopic findings were identical to the diagnostic imaging, where marked enlargement of the calvarium, and attenuated gyri and sulci were observed. Finally, hydrocephalus was confirmed. Here, we describe a case of hydrocephalus in a raccoon dog (Nyctereutes procyonoides).     

An enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies against the pathogenic haemoflagellate, Cryptobia salmositica Katz, and protection against cryptobiosis in juvenile rainbow trout, Oncorhynchus mykiss (Walbaum), inoculated with a live vaccine

Abstract. An enzyme-linked immunosorbent assay using dried blood on filter paper, was developed for the detection of antibodies against the haemoflagellate Cryptobia salmositica in juvenile rainbow trout, Oncorhynchus mykiss (Walbaum). Each fish (average weight about 5g) in three experimental groups was either inoculated with 20000 attenuated live C. salmositica vaccine, or inoculated with 2000 or 20000 pathogenic parasites per fish. The vaccine was effective in protecting juvenile trout 4 weeks after vaccination and antibody titers were higher in vaccinated and challenged fish than in unvaccinated and infected ones. Specific antibodies were detected one week post-infection (w.p.i.) with the pathogen and declined to low levels at 6 w.p.i. The high-dose group (20000 per fish) had antibody titres comparable to those of the vaccinated and challenged fish.     

Lernea cyprinacea L. (Copepoda: Caligidea) in Helostoma temmincki Cuvier & Valenciennes: the dynamics of resistance in recovered and naive fish

Abstract. All recovered and naive Helostoma temmincki lost their infections 30 days after homologous challenge with Lernaea cyprinacea. It is suggested that there is acquired protective immunity in recovered fish. No parasites were detected in five out of 20 recovered fish when the infective challenge dose was low; all naive fish (20) in the same tank were infected. In another experiment, all nine recovered fish were infected when the challenge infective dose was high. Recovered fish lost their infections (i.e. number of fish with no parasites and the number of parasites rejected) much faster than naive fish and this was very evident in the first 2 weeks after challenge. Parasites on recovered fish lost more egg sacs than naive fish during the same period. Eggs from parasites on recovered fish either did not hatch or were not infective or only caused a very low transitory infection in naive fish. It is suggested that, if no naive fish are introduced into a closed system for a period (and this has to be determined under field conditions) after an outbreak, then there will be no infective larvae in the water and the system will now be safe for restocking. This novel approach to control of the parasite L. cyprinacea and the spread of this disease will have to be carefully tested under field conditions.     

Cryptobia salmositica: cortisol increases the susceptibility of Salmo gairdneri Richardson to experimental cryptobiosis

Abstract. Intraperitoneal implants of cortisol (cortisol suspended in hydrogenated coconut oil) were used to induce a graded hypercortisolism in rainbow trout, Salmo gairdneri Richardson. There was no obvious reduction in circulating lymphocytes in cortisol-implanted rainbow trout (70, 140 or 210μg/g body weight). Cortisol-implanted fish infected with Cryptobia salmositica had significantly higher parasitaemia and lower antibody litres compared with controls infected with haemonagellate but given coconut oil implants. These confirm the immunodepressive effects of the steroid. The parasite was also more readily detected at the early stage of the infection (shorter prepatent period, more infected fish and higher parasitaemia) in cortisol-implanted fish (140 and 210 μg/g body weight) than in controls. The mortality of the infected cortisol-implanted fish was higher than that of the infected fish implanted with only coconut oil, or the cortisol-implanted but non-infected fish. This in vivo study suggests that protective immunity against C. salmositica is, in part, due to a humoral response.     

Impact of a pathogenic haemoflagellate, Cryptobia salmositica Katz, on the metabolism and swimming performance of rainbow trout, Oncorhynchus mykiss (Walbaum)

Abstract. Oxygen consumption of juvenile rainbow trout (5 g at 13°C) at moderate swimming speeds did not change significantly when infected with Cryptobia salmositica. However, significant reductions of as much as 44% of the maximum aerobic scope for activity and 24% of the critical swimming speed were observed when the parasitaemia reached a maximum of 57.6 × 10⁶ ml⁻¹ fish blood at 3 weeks post- infection. Blood haematocrit was significantly reduced from the initial 34.1 to 19.7% at 4 weeks post- infection, probably as a result of haemolysis by the parasite. The destruction of red blood cells clearly led to lower oxygen carrying capacity, and reduced respiratory and swimming performance.     

The immune response of rainbow trout, Salmo gairdneri Richardson, to the haemoflagellate, Cryptobia salmositica Katz, 1951

Abstract. Rainbow trout that recovered from experimental Cryptobia salmositica infection 6 and 10 weeks earlier were protected against multiple intraperitoneal challenges of 50 000 and 10 000 parasites isolated from infected fish. The immunity was non-sterile; low parasitaemias were detected following a larger challenge (112 000 parasites). The indirect haemagglutination test was used to detect C. salmositica -specific agglutimns. Antibody titers increased during the first 18 weeks of infection. The infectivity of cultured C. salmositica was neutralized by incubation in heat-inactivated immune plasma. Infectivity of C, salmositica from infected fish was not neutralized by similar treatment. Complement fixing antibody was detected using the in vitro immune lysis test. Immune lysis occurred when cultured C. salmositica were used. Adoptive transfer of both leucocytes and plasma from immune fish conferred partial protection against the parasite in naive recipients. Complement fixing antibody may be important during early acute infection while phagocytosis may be important during the later chronic phase.